%0 Journal Article %J Journal of Hazardous Materials %D 2023 %T Assessing indicators of arsenic toxicity using variable fluorescence in a commercially valuable microalgae: physiological and toxicological aspects %A Das, Shagnika %A Lizon, Fabrice %A Gevaert, François %A Bialais, Capucine %A Duong, Gwendoline %A Ouddane, Baghdad %A Souissi, Sami %K Arsenic bioaccumulation %K de-epoxidation ratio (DR) %K Optical absorption cross section %K pigment concentrations %K RCC1537 %X Indicators signaling Arsenic (As) stress through physiology of microalgae using non-destructive methods like variable fluorescence are rare but requisite. This study reports stress markers indicating arsenic (As) toxicity (in two concentrations 11.25µg/L and 22.5µg/L compared to a control) exposed to a microalga (Diacronema lutheri), using fast repetition rate fluorometry (FRRf). Growth and physiological parameters such as cell density, chl a and the maximum quantum yield Fv/Fm showed coherence and impeded after the exponential phase (day 9 - day 12) in As treatments compared to the control (p < 0.05). On contrary photo-physiological constants were elevated showing higher optical (aLHII) and functional [Sigma (σPSII)] absorption cross-section for the As treatments (p < 0.05) further implying the lack of biomass production yet an increase in light absorption. In addition, As exposure increased the energy dissipation by heat (NPQ-NSV) showing a strong relationship with the de-epoxidation ratio (DR) involving photoprotective pigments. Total As bioaccumulation by D. lutheri showed a strong affinity with Fe adsorption throughout the algal growth curve. This study suggests some prompt photo-physiological proxies signaling As contamination and endorsing its usefulness in risk assessments, given the high toxicity and ubiquitous presence of As in the ecosystem. %B Journal of Hazardous Materials %P 131215 %8 mar %G eng %U https://www.sciencedirect.com/science/article/pii/S0304389423004971 %R 10.1016/j.jhazmat.2023.131215 %0 Journal Article %J Environmental Microbiology %D 2023 %T The Bay of Bengal exposes abundant photosynthetic picoplankton and newfound diversity along salinity-driven gradients %A Strauss, Jan %A Choi, Chang Jae %A Grone, Jonathan %A Wittmers, Fabian %A Jimenez, Valeria %A Makareviciute-Fichtner, Kriste %A Bachy, Charles %A Jaeger, Gualtiero Spiro %A Poirier, Camille %A Eckmann, Charlotte %A Spezzano, Rachele %A Löscher, Carolin R. %A Sarma, V. V. S. S. %A Mahadevan, Amala %A Worden, Alexandra Z. %K RCC393 %K RCC809 %X The Bay of Bengal (BoB) is a 2,600,000 km2 expanse in the Indian Ocean upon which many humans rely. However, the primary producers underpinning food chains here remain poorly characterized. We examined phytoplankton abundance and diversity along strong BoB latitudinal and vertical salinity gradients-which have low temperature variation (27-29°C) between the surface and subsurface chlorophyll maximum (SCM). In surface waters, Prochlorococcus averaged 11.7 ± 4.4 × 104  cells ml-1 , predominantly HLII, whereas LLII and 'rare' ecotypes, HLVI and LLVII, dominated in the SCM. Synechococcus averaged 8.4 ± 2.3 × 104  cells ml-1 in the surface, declined rapidly with depth, and population structure of dominant Clade II differed between surface and SCM; Clade X was notable at both depths. Across all sites, Ostreococcus Clade OII dominated SCM eukaryotes whereas communities differentiated strongly moving from Arabian Sea-influenced high salinity (southerly; prasinophytes) to freshwater-influenced low salinity (northerly; stramenopiles, specifically, diatoms, pelagophytes, and dictyochophytes, plus the prasinophyte Micromonas) surface waters. Eukaryotic phytoplankton peaked in the south (1.9 × 104  cells ml-1 , surface) where a novel Ostreococcus was revealed, named here Ostreococcus bengalensis. We expose dominance of a single picoeukaryote and hitherto 'rare' picocyanobacteria at depth in this complex ecosystem where studies suggest picoplankton are replacing larger phytoplankton due to climate change. %B Environmental Microbiology %G eng %R 10.1111/1462-2920.16431 %0 Generic %D 2023 %T Biological and genomic resources for the cosmopolitan phytoplankton Bathycoccus: Insights into genetic diversity and major structural variations %A Dennu, Louis %A Devic, Martine %A Rigonato, Janaina %A Falciatore, Angela %A Lozano, Jean-Claude %A Vergé, Valérie %A Mariac, Cédric %A Jaillon, Olivier %A Team, The Dark Edge genomics sampling %A Sabot, François %A Bouget, François-Yves %K RCC1615 %K RCC1868 %K RCC4222 %K RCC4752 %K RCC5417 %K RCC685 %K RCC716 %X Population-scale sequencing has become a standard practice to explore the natural genetic diversity underlying adaptation, notably in land plants. However, current sequencing initiatives for eukaryotic phytoplankton primarily concentrate on creating reference genomes for model organisms and characterizing natural communities through metagenomics approaches. Consequently, few species have been thoroughly sequenced and intraspecific genetic diversity remains virtually undescribed, limiting our understanding of diversity and adaptation mechanisms. Here we report a biological and genomic resource to explore the genetic diversity of the cosmopolitan and ecologically important Bathycoccus genus. To span broad geographical and temporal scales, we selected available strains but also isolated and genotyped strains from both the Banyuls bay (Mediterranean sea) and the Baffin bay (Arctic ocean). By combining ONT long reads and Illumina short reads technologies, we produced and annotated 28 Bathycoccus sp. de novo assembled genomes of high quality, including 24 genomes of Bathycoccus prasinos strains along a latitudinal gradient between 40° and 78° North, one reference genome of the Bathycoccus calidus species and 3 genomes of a yet undescribed Bathycoccus species named Bathycoccus catiminus. We assessed the genetic diversity of this genus through phylogenomic analyses and highlighted the central role of this genomic resource in providing new insights into the diversity of outlier chromosomal structures. The Bathycoccus biological and genomic resources offer a robust framework for investigating the diversity and adaptation mechanisms of eukaryotic phytoplankton in the Ocean. Significance statement Comparative and functional approaches for the study of eukaryotic phytoplankton and their adaptation to latitudes and seasons that rely on extensive biological and genomic resources are currently lacking. Here we report such resources and describe the natural diversity of the cosmopolitan phytoplankton Bathycoccus, providing insights into its species and intraspecific diversity and establishing it as a robust model for functional and ecological studies. %I bioRxiv %8 oct %G eng %U https://www.biorxiv.org/content/10.1101/2023.10.16.562038v1 %R 10.1101/2023.10.16.562038 %0 Journal Article %J Scientific Reports %D 2023 %T Bioprospecting for industrially relevant exopolysaccharide-producing cyanobacteria under Portuguese simulated climate %A Cruz, José Diogo %A Delattre, Cédric %A Felpeto, Aldo Barreiro %A Pereira, Hugo %A Pierre, Guillaume %A Morais, João %A Petit, Emmanuel %A Silva, Joana %A Azevedo, Joana %A Elboutachfaiti, Redouan %A Maia, Inês B. %A Dubessay, Pascal %A Michaud, Philippe %A Vasconcelos, Vitor %K Biochemistry %K Biotechnology %K Microbiology %K rcc2380 %X Cyanobacterial exopolysaccharides (EPS) are potential candidates for the production of sustainable biopolymers. Although the bioactive and physicochemical properties of cyanobacterial-based EPS are attractive, their commercial exploitation is limited by the high production costs. Bioprospecting and characterizing novel EPS-producing strains for industrially relevant conditions is key to facilitate their implementation in various biotechnological applications and fields. In the present work, we selected twenty-five Portuguese cyanobacterial strains from a diverse taxonomic range (including some genera studied for the first time) to be grown in diel light and temperature, simulating the Portuguese climate conditions, and evaluated their growth performance and proximal composition of macronutrients. Synechocystis and Cyanobium genera, from marine and freshwater origin, were highlighted as fast-growing (0.1–0.2 g L−1 day−1) with distinct biomass composition. Synechocystis sp. LEGE 07367 and Chroococcales cyanobacterium LEGE 19970, showed a production of 0.3 and 0.4 g L−1 of released polysaccharides (RPS). These were found to be glucan-based polymers with high molecular weight and a low number of monosaccharides than usually reported for cyanobacterial EPS. In addition, the absence of known cyanotoxins in these two RPS producers was also confirmed. This work provides the initial steps for the development of cyanobacterial EPS bioprocesses under the Portuguese climate. %B Scientific Reports %V 13 %P 13561 %G eng %U https://www.nature.com/articles/s41598-023-40542-6 %R 10.1038/s41598-023-40542-6 %0 Generic %D 2023 %T Coccolithophorids precipitate carbonate in clumped isotope equilibrium with seawater %A Clark, Alexander J. %A Torres-Romero, Ismael %A Jaggi, Madalina %A Bernasconi, Stefano M. %A Stoll, Heather M. %K RCC1130 %K RCC1303 %K RCC3370 %X Numerous recent studies have tested the clumped isotope (Δ47) thermometer on a variety of biogenic carbonates such as foraminifera and bivalves and showed that all follow a common calibration. While the sample size requirements for a reliable Δ47 measurement have decreased over the years, the availability and preservation of many biogenic carbonates is still 10 limited and/or require substantial time to be extracted from sediments in sufficient amounts. We thus determined the Δ47temperature relationship for coccolith carbonate, which is abundant and often well-preserved in sediments. The carbon and oxygen isotopic compositions of coccolith calcite have limited use in palaeoenvironmental reconstructions due to physiological effects that cause variability in the carbon and oxygen isotopic values. However, the relatively limited data available suggest that clumped isotopes may not be influenced by these effects. We cultured three species of coccolithophores in well15 constrained carbonate system conditions with a CO2(aq) between 5 and 45 μM and temperatures between 6°C and 27°C. %I EGUsphere %8 nov %G eng %U https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2581/ %9 preprint %R 10.5194/egusphere-2023-2581 %0 Journal Article %J Journal of Experimental Marine Biology and Ecology %D 2023 %T Comparison of thermal traits between non-toxic and potentially toxic marine phytoplankton: Implications to their responses to ocean warming %A Edullantes, Brisneve %A Low-Decarie, Etienne %A Steinke, Michael %A Cameron, Tom %K Growth experiment %K Growth models %K Microalgal ecophysiology %K RCC2649 %K RCC291 %K RCC3034 %K Thermal performance %K Thermal physiology %K Toxic microalgae %X Understanding the effect of temperature on growth in marine phytoplankton is crucial in predicting the biogeography and phenology of algal blooms in the warming ocean. Here, we investigated the temperature dependence of the growth of non-toxic and potentially toxic marine phytoplankton. Using non-toxic strains (Prorocentrum sp. NRR 188, Prorocentrum micans CCAP 1136/15, and Alexandrium tamutum PARALEX 242) and potentially toxic strains (Prorocentrum minimum Poulet, Prorocentrum lima CCAP 1136/11, and Alexandrium minutum PARALEX 246) of dinoflagellates as test organisms, we measured their growth rates along a wide temperature gradient and estimated their maximum growth rates, thermal traits (e.g. thermal optima (Topt), critical thermal minima (CTmin), critical thermal maximum (CTmax), fundamental thermal niche (FTN), and skewness), thermal sensitivity, and warming vulnerability. To allow a comparison of these traits with an adequate number of observations, we independently analyzed datasets compiled from published laboratory experiments. Our experiments revealed that the temperature traits were independent of the toxicity of phytoplankton, except for Topt and CTmax. Also, the results of the analysis of the published datasets showed that maximum growth rates and thermal traits were comparable between non-toxic and potentially toxic phytoplankton. Our findings suggest that non-toxic and potentially toxic phytoplankton have generally comparable temperature traits that they can use to respond to climate change. However, depending on the climate scenario, non-toxic phytoplankton may be more vulnerable to warming than potentially toxic phytoplankton. Further studies are needed to improve our understanding of the response of marine phytoplankton to temperature, which can advance our ability to predict algal blooms in response to ongoing climate change. %B Journal of Experimental Marine Biology and Ecology %V 562 %P 151883 %G eng %U https://www.sciencedirect.com/science/article/pii/S0022098123000151 %R 10.1016/j.jembe.2023.151883 %0 Journal Article %J Small Structures %D 2023 %T Crystallization of Coccolith Calcite at Different Life-Cycle Phases Exhibits Distinct Degrees of Cellular Confinement %A Ben-Joseph, Oz %A de Haan, Diede %A Rechav, Katya %A Shimoni, Eyal %A Levin-Zaidman, Smadar %A Langer, Gerald %A Probert, Ian %A Wheeler, Glen L. %A Gal, Assaf %K biomineralization %K calcites %K Coccoliths %K crystal growths %K haploid–diploid life cycles %K RCC1181 %K RCC3777 %X Coccolithophores are a group of unicellular marine algae that shape global geochemical cycles via the production of calcium carbonate crystals. Interestingly, different life-cycle phases of the same coccolithophore species produce very different calcitic scales, called coccoliths. In the widely studied diploid phase, the crystals have anisotropic and complex morphologies, while haploid cells produce coccoliths consisting solely of calcite crystals with simple rhombohedral morphology. Understanding how these two life-cycle phases control crystallization is a highly sought-after goal, yet, haploid phase crystallization has rarely been studied, and the process by which they form is unknown. Herein, advanced electron microscopy is employed to elucidate the cellular architecture of the calcification process in haploid cells. The results show that in contrast to diploid-phase calcification, the coccolith-forming vesicle of haploid-phase cells is voluminous. In this solution-like environment, the crystals nucleate and grow asynchronously in a process that resembles calcite growth in bulk solution, leading to the simple morphologies of the crystals. The two distinct mineralization regimes of coccolithophore life-cycle phases suggest that cellular architecture, and specifically confinement of the crystallization process, is a pivotal determinant of biomineral morphology and assembly. %B Small Structures %V n/a %P 2200353 %G eng %U https://onlinelibrary.wiley.com/doi/abs/10.1002/sstr.202200353 %R 10.1002/sstr.202200353 %0 Journal Article %J Applied Sciences %D 2023 %T The Diatom Cylindrotheca closterium and the Chlorophyll Breakdown Product Pheophorbide a for Photodynamic Therapy Applications %A Saide, Assunta %A Riccio, Gennaro %A Ianora, Adrianna %A Lauritano, Chiara %K biotechnological applications %K cancer %K Microalgae %K Pheophorbide \textita %K photodynamic therapy %K RCC1712 %K \textitCylindrotheca closterium %X Microalgae, eukaryotic unicellular plants that are distributed worldwide, have been shown to exert anti-proliferative and anticancer activities on various human cancer cell lines. An example of a microalgal bioactive compound is a chlorophyll breakdown product named Pheophorbide a (Ppa), which has been reported to have anti-proliferative properties against various cell lines. This compound has also been tested with light exposure in photodynamic therapy for cancer treatment. In this paper, we screened eleven marine microalgae against a panel of cancer cells, and evaluated the synergistic anti-proliferative effect with Pheophorbide a, with and without photo-activation. The results showed significant anti-proliferative activity against melanoma cells when Ppa was combined with fraction E of the diatom Cylindrotheca closterium plus 1 h photo-activation. Its activity was also analyzed using gene expression and Western blot experiments. Altogether, these data give new insights into the possible application of microalgae for photodynamic therapy. %B Applied Sciences %V 13 %P 2590 %G eng %U https://www.mdpi.com/2076-3417/13/4/2590 %R 10.3390/app13042590 %0 Generic %D 2023 %T Effects of Nitrogen Starvation on Growth and Biochemical Composition of Some Microalgae Species %A Şi̇Ri̇N, Pınar AKDOĞAN %A Serdar, Serpil %K RCC2967 %X Abstract Nitrogen is one of the most important nutrient sources for the growth of microalgae. We studied the effects of nitrogen starvation on the growth responses, biochemical composition and fatty acid profile of Dunaliella tertiolecta, Phaeodactylum tricornutum and Nannochloropsis oculata . The lack of nitrogen caused changes in carbohydrate, protein, lipid and fatty acid composition in all examined microalgae. The carbohydrate content increased 59% in D. tertiolecta , while the lipid level increased 139% in P. tricornutum under nitrogen stress conditions. Nitrogen starvation increased the oligosaccharide and polysaccharide contents of D. tertiolecta 4.18-fold and 3.77-fold, respectively. Furthermore, triacylglycerol (TAG) levels in N. oculata and P. tricornutum increased 2.3-fold and 7.4-fold, respectively. The dramatic increase in the amount of TAG is important for the use of these microalgae as raw materials in biodiesel. Nitrogen starvation increased the amounts of oligosaccharides and polysaccharides of D. tertiolecta , while increased eicosapentaenoic acid (EPA) in N. oculata and docosahexaenoic acid (DHA) content in P. tricornutum . The amount of polyunsaturated fatty acids (PUFAs), EPA, DHA, oligosaccharides and polysaccharides in microalgal species can be increased without using the too costly nitrogen source in the culture conditions, which can reduce the most costly of living feeding. %I In Review %8 apr %G eng %U https://www.researchsquare.com/article/rs-2787376/v1 %9 preprint %R 10.21203/rs.3.rs-2787376/v1 %0 Journal Article %J Journal of Experimental Botany %D 2023 %T Genetic and physiological responses to light quality in a deep ocean ecotype of Ostreococcus, an ecologically important photosynthetic picoeukaryote %A Sands, Elizabeth %A Davies, Sian %A Puxty, Richard John %A Vergé, Valérie %A Bouget, François-Yves %A Scanlan, David John %A Carré, Isabelle Alice %K Rcc141 %K RCC4221 %K RCC745 %K RCC809 %X Abstract Phytoplankton are exposed to dramatic variations in light quality when cells are carried by upwelling or downwelling currents or encounter sediment. We investigated the potential impact of light quality changes in Ostreococcus, a key marine photosynthetic picoeukaryote, by analysing changes in its transcriptome, pigment content and photophysiology after acclimation to monochromatic red, green or blue light. The clade B species RCC809, isolated from the deep euphotic zone of the tropical Atlantic Ocean, responded to blue light by accelerating cell division at the expense of storage reserves and by increasing the relative level of blue-light absorbing pigments. RCC809 responded to red and green light by increasing its potential for photoprotection. In contrast, the clade A species OTTH0595, which originates from a shallow water environment, showed no difference in photosynthetic properties and minor differences in carotenoid contents between light qualities. This was associated with the loss of candidate lightquality responsive promoter motifs identified in RCC809 genes. These results demonstrate that light quality can have a major influence on the physiology of eukaryotic phytoplankton and suggest that different light quality environments can drive selection for diverse patterns of responsiveness and environmental niche partitioning. %B Journal of Experimental Botany %P erad347 %G eng %U https://academic.oup.com/jxb/advance-article/doi/10.1093/jxb/erad347/7258950 %R 10.1093/jxb/erad347 %0 Journal Article %J ISME Communications %D 2023 %T Genomic copy number variability at the genus, species and population levels impacts in situ ecological analyses of dinoflagellates and harmful algal blooms %A Ruvindy, Rendy %A Barua, Abanti %A Bolch, Christopher J. S. %A Sarowar, Chowdhury %A Savela, Henna %A Murray, Shauna A. %K Molecular ecology %K Molecular Evolution %K RCC3145 %K RCC4874 %K RCC4876 %K RCC4877 %K RCC4879 %X The application of meta-barcoding, qPCR, and metagenomics to aquatic eukaryotic microbial communities requires knowledge of genomic copy number variability (CNV). CNV may be particularly relevant to functional genes, impacting dosage and expression, yet little is known of the scale and role of CNV in microbial eukaryotes. Here, we quantify CNV of rRNA and a gene involved in Paralytic Shellfish Toxin (PST) synthesis (sxtA4), in 51 strains of 4 Alexandrium (Dinophyceae) species. Genomes varied up to threefold within species and \textasciitilde7-fold amongst species, with the largest (A. pacificum, 130 ± 1.3 pg cell−1 /\textasciitilde127 Gbp) in the largest size category of any eukaryote. Genomic copy numbers (GCN) of rRNA varied by 6 orders of magnitude amongst Alexandrium (102– 108 copies cell−1) and were significantly related to genome size. Within the population CNV of rRNA was 2 orders of magnitude (105 – 107 cell−1) in 15 isolates from one population, demonstrating that quantitative data based on rRNA genes needs considerable caution in interpretation, even if validated against locally isolated strains. Despite up to 30 years in laboratory culture, rRNA CNV and genome size variability were not correlated with time in culture. Cell volume was only weakly associated with rRNA GCN (20–22% variance explained across dinoflagellates, 4% in Gonyaulacales). GCN of sxtA4 varied from 0–102 copies cell−1, was significantly related to PSTs (ng cell−1), displaying a gene dosage effect modulating PST production. Our data indicate that in dinoflagellates, a major marine eukaryotic group, low-copy functional genes are more reliable and informative targets for quantification of ecological processes than unstable rRNA genes. %B ISME Communications %V 3 %P 1–11 %8 jul %G eng %U https://www.nature.com/articles/s43705-023-00274-0 %R 10.1038/s43705-023-00274-0 %0 Generic %D 2023 %T An INDEL genomic approach to explore population diversity of phytoplankton : \textit{Bathycoccus , a case study %A Devic, Martine %A Mariac, Cédric %A Vergé, Valérie %A Schatt, Philipe %A Dennu, Louis %A Lozano, Jean-Claude %A Bouget, François-Yves %A Sabot, François %K RCC1613 %K RCC1615 %K RCC1868 %K RCC4222 %K RCC4752 %K RCC5417 %K RCC685 %X Abstract Although metabarcoding has generated large dataset on world-wide phytoplankton species diversity, little is known about the intraspecies diversity underlying adaptation to environmental niches. To gain insight into population diversity, a novel INDEL based method was developed on Bathycoccus prasinos . Oxford Nanopore Technology (ONT) sequencing was first used to characterise structural variants (SV) among the genomes of Bathycoccus sampled from geographically distinct regions in the world ocean. Markers derived from INDEL were validated by PCR and sequencing in the world-wide strains. These markers were then used to genotype 55 Bathycoccus strains isolated during the winter bloom 2018-2019 in the bay of Banyuls-sur-Mer. With five markers, eight Multi Loci Genotypes (MLG) were determined, two of which represented 53% and 29% of the isolates. Physiological studies confirmed that isolates are phenotypically different, cells isolated in February growing better at low temperature than those isolated in December and January. When tested directly on environmental samples, two diversity markers showed a similar allele frequency in sea water as in individual Bathycoccus strains isolated at the same period. We conclude that these markers constitute a resource to identify the most abundant variant alleles in a given bloom. A follow-up on three consecutive blooms revealed differences in allele abundance during the course of a bloom, particularly at initiation and between years. This INDEL-based genotyping constitutes a new methodological approach that may be used to assess the population structure and diversity of other species. %I Ecology %G eng %U http://biorxiv.org/lookup/doi/10.1101/2023.02.09.527951 %9 preprint %R 10.1101/2023.02.09.527951 %0 Journal Article %J Algal Research %D 2023 %T Novel exopolysaccharide produced by the marine dinoflagellate Heterocapsa AC210: Production, characterization, and biological properties %A Concórdio-Reis, Patrícia %A Cardeira, Martim %A Macedo, Ana Catarina %A Ferreira, Sónia S. %A Serra, Ana Teresa %A Coimbra, Manuel A. %A Amorim, Ana %A Reis, Maria A. M. %A Freitas, Filomena %K Anti-inflammatory %K Cytotoxicity %K Dinoflagellates %K Exopolysaccharide production %K Marine microalgae %K RCC1514 %K sp. AC210 %X Marine microalgae are promising sources of novel valuable biomolecules such as polysaccharides. In this study, the dinoflagellate Heterocapsa sp. AC210 was described as a new exopolysaccharide (EPS) producer. The cultivation and EPS production in bioreactor was evaluated for the first time in detail. The EPS was composed of seven different sugar monomers, including fucose and glucosamine, which are quite rare and have never been reported in dinoflagellates' EPS. Moreover, the EPS had a high content of sulphate, which is often associated with biological properties. Cytotoxicity was accessed and the results showed that the EPS did not reduce cell viability for concentrations up to 1 g L−1. Additionally, antioxidant and anti-inflammatory assays demonstrated that the EPS reduced by 18 % the intracellular reactive oxygen species and decreased up to 79.3 % and 46.2 % of IL-8 and IL-6 secretion in keratinocytes, which supports its potential application in the cosmeceutical and biomedical fields. %B Algal Research %V 70 %P 103014 %G eng %U https://www.sciencedirect.com/science/article/pii/S2211926423000474 %R 10.1016/j.algal.2023.103014 %0 Journal Article %J Journal of Experimental Botany %D 2023 %T A phospho-dawn of protein modification anticipates light onset in the picoeukaryote \textit{O. tauri %A Noordally, Zeenat B %A Hindle, Matthew M %A Martin, Sarah F %A Seaton, Daniel D %A Simpson, T Ian %A Le Bihan, Thierry %A Millar, Andrew J %K RCC745 %X Abstract Diel regulation of protein levels and protein modification had been less studied than transcript rhythms. Here, we compare transcriptome data under light-dark cycles to partial proteome and phosphoproteome data, assayed using shotgun mass-spectrometry, from the alga Ostreococcus tauri, the smallest free-living eukaryote. 10% of quantified proteins but two-thirds of phosphoproteins were rhythmic. Mathematical modelling showed that light-stimulated protein synthesis can account for the observed clustering of protein peaks in the daytime. Prompted by night-peaking and apparently dark-stable proteins, we also tested cultures under prolonged darkness, where the proteome changed less than under the diel cycle. Among the dark-stable proteins were prasinophyte-specific sequences that were also reported to accumulate when O. tauri formed lipid droplets. In the phosphoproteome, 39% of rhythmic phospho-sites reached peak levels just before dawn. This anticipatory phosphorylation suggests that a clock-regulated phospho-dawn prepares green cells for daytime functions. Acid-directed and proline-directed protein phosphorylation sites were regulated in antiphase, implicating the clock-related, casein kinases 1 and 2 in phase-specific regulation, alternating with the CMGC protein kinase family. Understanding the dynamic phosphoprotein network should be facilitated by the minimal kinome and proteome of O. tauri. The data are available from ProteomeXchange, with identifiers PXD001734, PXD001735 and PXD002909. %B Journal of Experimental Botany %P erad290 %8 jul %G eng %U https://academic.oup.com/jxb/advance-article/doi/10.1093/jxb/erad290/7229478 %R 10.1093/jxb/erad290 %0 Generic %D 2023 %T Population dynamics of the cosmopolitan eukaryotic picophytoplankton Bathycoccus during seasonal blooms in the bay of Banyuls sur Mer (North Western Mediterranean sea) %A Devic, Martine %A Mariac, Cédric %A Vergé, Valérie %A Schatt, Philipe %A Dennu, Louis %A Lozano, Jean-Claude %A Bouget, François-Yves %A Sabot, François %K RCC1613 %K RCC1615 %K RCC1868 %K RCC4222 %K RCC4752 %K RCC5417 %K RCC685 %X Abstract Although Bathycoccus is one of the most abundant picophytoplankton, little is known about the genetic diversity underlying its adaptation to ecological niches. In this study, the diversity of Bathycoccus populations during their annual bloom in the Mediterranean bay of Banyuls France was assessed by an INDEL based approach. Oxford Nanopore Technology (ONT) was used to characterise structural variants (SV) among the genomes of Bathycoccus sampled from geographically distinct regions in the world ocean. Markers derived from INDEL were validated by PCR and sequencing in the world-wide strains. These markers were then used to genotype 55 Bathycoccus strains isolated during the winter bloom 2018-2019 in Banyuls. With five markers, eight Multi Loci Genotypes (MLG) were determined, two of which represented 53% and 29% of the isolates. Physiological studies confirmed that isolates are phenotypically different, cells isolated in February growing better at low temperature than those isolated in December. When tested on environmental samples, two diversity markers showed a similar allele frequency in sea water as in individual Bathycoccus strains isolated at the same period. We conclude that these markers constitute a resource to identify the most abundant variant alleles in a given bloom. A follow-up on three consecutive blooms revealed differences in allele abundance during the course of a bloom, particularly at initiation, and between years. In addition to Bathycoccus prasinos , two other species of Bathycoccus were identified including the recently described species B. calidus and a novel species B. catiminus , suggesting that species diversity of the genus Bathycoccus may be underestimated. %I BioRxiv %G eng %U http://biorxiv.org/lookup/doi/10.1101/2023.02.09.527951 %9 preprint %R 10.1101/2023.02.09.527951 %0 Journal Article %J Algal Research %D 2023 %T Selection of photosynthetic microorganisms grown in artificial saline industrial effluents with liquid digestate: From screening to consortium cultures %A Parsy, Aurélien %A Sambusiti, Cecilia %A Baldoni-Andrey, Patrick %A Périé, Frédéric %A Guyoneaud, Rémy %K Aquifer water %K cyanobacteria %K Liquid digestate %K Microalgae %K Produced water %K RCC4223 %K RCC537 %K rcc752 %X The objective of this study was to determine the feasibility of using saline industrial streams as a culture medium to grow microalgae and cyanobacteria. Experiments were performed to determine the extent of the growth in artificial saline produced water and aquifer water supplemented with liquid digestate. Tests were performed in 96-wells microplates. Media were composed with different proportion of saline artificial produced water or aquifer water supplemented with 5% v/v liquid digestate (final concentrations: 149–195 mgN·L−1, 1.5–2.7 mgP·L−1). Media were completed to 100 % with artificial seawater, corresponding to final salinities of 40, 70 and 100 g·L−1. D. salina, N. oceanica and T. suecica showed the best growth rates. They were selected to perform mixed cultures in 80 mL tubes in the same culture media. Population evolutions were followed for 19 days. Depending on salinity and industrial effluent used, different species became predominant over the two others (N. oceanica, T. suecica and D. salina. at 40, 70 and 100 g·L−1, respectively). It appears that mixed culture is a good solution to have a biomass production during a culture process where the culture media will evolve in terms of salinity and composition. %B Algal Research %P 103061 %8 mar %G eng %U https://www.sciencedirect.com/science/article/pii/S2211926423000942 %R 10.1016/j.algal.2023.103061 %0 Journal Article %J Geophysical Research Letters %D 2023 %T Stable Carbon Isotope Signature of Methane Released from Phytoplankton %A Klintzsch, Thomas %A Geisinger, Hannah %A Wieland, Anna %A Langer, Gerald %A Nehrke, Gernot %A Bizic, Mina %A Greule, Markus %A Lenhart, Katharina %A Borsch, Christian %A Schroll, Moritz %A Keppler, Frank %K RCC1216 %K ⛔ No DOI found %X Aquatic ecosystems play an important role in global methane cycling and many field studies have reported methane supersaturation in the oxic surface mixed layer (SML) of the ocean and in the epilimnion of lakes. The origin of methane formed under oxic condition is hotly debated and several pathways have recently been offered to explain the ‘methane paradox’. In this context, stable isotope measurements have been applied to constrain methane sources in supersaturated oxygenated waters. Here we present stable carbon isotope signatures for six widespread marine phytoplankton species, three haptophyte algae and three cyanobacteria, incubated under laboratory conditions. The observed isotopic patterns implicate that methane formed by phytoplankton might be clearly distinguished from methane produced by methanogenic archaea. Comparing results from phytoplankton experiments with isotopic data from field measurements, suggests that algal and cyanobacterial populations may contribute substantially to methane formation observed in the SML of oceans and lakes. %B Geophysical Research Letters %8 feb %G eng %U https://essopenarchive.org/users/587513/articles/625160-stable-carbon-isotope-signature-of-methane-released-from-phytoplankton?commit=633a121ee07c48e6c59ffeca06fd5d5ebe1df4d4 %R 10.22541/essoar.167689993.32180072/v1 %0 Journal Article %J Cell Reports Methods %D 2023 %T Tailoring confocal microscopy for real-time analysis of photosynthesis at single-cell resolution %A Storti, Mattia %A Hsine, Haythem %A Uwizeye, Clarisse %A Bastien, Olivier %A Yee, Daniel P. %A Chevalier, Fabien %A Decelle, Johan %A Giustini, Cécile %A Béal, Daniel %A Curien, Gilles %A Finazzi, Giovanni %A Tolleter, Dimitri %K rcc1383 %X Photoautotrophs’ environmental responses have been extensively studied at the organism and ecosystem level. However, less is known about their photosynthesis at the single-cell level. This information is needed to understand photosynthetic acclimation processes, as light changes as it penetrates cells, layers of cells, or organs. Furthermore, cells within the same tissue may behave differently, being at different developmental/ physiological stages. Here, we describe an approach for single-cell and subcellular photophysiology based on the customization of confocal microscopy to assess chlorophyll fluorescence quenching by the saturation pulse method. We exploit this setup to (1) reassess the specialization of photosynthetic activities in developing tissues of non-vascular plants; (2) identify a specific subpopulation of phytoplankton cells in marine photosymbiosis, which consolidate energetic connections with their hosts; and (3) examine the link between light penetration and photoprotection responses inside the different tissues that constitute a plant leaf anatomy. %B Cell Reports Methods %P 100568 %G eng %U https://linkinghub.elsevier.com/retrieve/pii/S2667237523002126 %R 10.1016/j.crmeth.2023.100568 %0 Journal Article %J MicrobiologyOpen %D 2023 %T Transcriptomics‐guided identification of an algicidal protease of the marine bacterium Kordia algicida OT‐1 %A Syhapanha, Kristy S. %A Russo, David A. %A Deng, Yun %A Meyer, Nils %A Poulin, Remington X. %A Pohnert, Georg %K RCC75 %X In recent years, interest in algicidal bacteria has risen due to their ecological importance and their potential as biotic regulators of harmful algal blooms. Algicidal bacteria shape the plankton communities of the oceans by inhibiting or lysing microalgae and by consuming the released nutrients. Kordia algicida strain OT‐1 is a model marine algicidal bacterium that was isolated from a bloom of the diatom Skeletonema costatum. Previous work has suggested that algicidal activity is mediated by secreted proteases. Here, we utilize a transcriptomics‐guided approach to identify the serine protease gene KAOT1_RS09515, hereby named alpA1 as a key element in the algicidal activity of K. algicida. The protease AlpA1 was expressed and purified from a heterologous host and used in in vitro bioassays to validate its activity. We also show that K. algicida is the only algicidal species within a group of four members of the Kordia genus. The identification of this algicidal protease opens the possibility of real‐time monitoring of the ecological impact of algicidal bacteria in natural phytoplankton blooms., Algicidal bacteria shape the plankton communities of the oceans by lysing microalgae and consuming the released nutrients. Kordia algicida is an environmentally relevant marine bacterium whose algicidal activity is mediated by secreted proteases. In this study, we utilize a transcriptomics‐guided approach to identify the secreted serine protease AlpA1 as a key factor in the algicidal process. This discovery offers new approaches for the real‐time monitoring and manipulation of algicidal bacteria in algal blooms. %B MicrobiologyOpen %V 12 %P e1387 %G eng %U https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10565126/ %R 10.1002/mbo3.1387 %0 Journal Article %J Frontiers in Marine Science %D 2023 %T Viral infection impacts the 3D subcellular structure of the abundant marine diatom Guinardia delicatula %A Walde, Marie %A Camplong, Cyprien %A de Vargas, Colomban %A Baudoux, Anne-claire %A Simon, Nathalie %K RCC3083 %K RCC5812 %X Viruses are key players in marine ecosystems where they infect abundant marine microbes. RNA viruses are emerging as key members of the marine virosphere. They have recently been identified as a potential source of mortality in diatoms, a group of microalgae that accounts for roughly 40% of the primary production in the ocean. Despite their likely importance, their impacts on host populations and ecosystems remain difficult to assess. In this study, we introduce an innovative approach that combines automated 3D confocal microscopy with quantitative image analysis and physiological measurements to expand our understanding of viral infection. We followed different stages of infection of the bloom-forming diatom Guinardia delicatula by the RNA virus GdelRNAV-04 until the complete lysis of the host. From 20h after infection, we observed quantifiable changes in subcellular host morphology and biomass. Our microscopy monitoring also showed that viral infection of G. delicatula induced the formation of auxospores as a probable defense strategy against viruses. Our method enables the detection of discriminative morphological features on the subcellular scale and at high throughput for comparing populations, making it a promising approach for the quantification of viral infections in the field in the future. %B Frontiers in Marine Science %V 9 %G eng %U https://www.frontiersin.org/articles/10.3389/fmars.2022.1034235 %R 10.3389/fmars.2022.1034235 %0 Journal Article %J Current Biology %D 2023 %T The V-type ATPase enhances photosynthesis in marine phytoplankton and further links phagocytosis to symbiogenesis %A Yee, Daniel P. %A Samo, Ty J. %A Abbriano, Raffaela M. %A Shimasaki, Bethany %A Vernet, Maria %A Mayali, Xavier %A Weber, Peter K. %A Mitchell, B. Greg %A Hildebrand, Mark %A Decelle, Johan %A Tresguerres, Martin %K RCC3387 %X Diatoms, dinoflagellates, and coccolithophores are dominant groups of marine eukaryotic phytoplankton that are collectively responsible for the majority of primary production in the ocean.1 These phytoplankton contain additional intracellular membranes around their chloroplasts, which are derived from ancestral engulfment of red microalgae by unicellular heterotrophic eukaryotes that led to secondary and tertiary endosymbiosis.2 However, the selectable evolutionary advantage of these membranes and the physiological significance for extant phytoplankton remain poorly understood. Since intracellular digestive vacuoles are ubiquitously acidified by V-type H+-ATPase (VHA),3 proton pumps were proposed to acidify the microenvironment around secondary chloroplasts to promote the dehydration of dissolved inorganic carbon (DIC) into CO2, thus enhancing photosynthesis.4,5 We report that VHA is localized around the chloroplasts of centric diatoms and that VHA significantly contributes to their photosynthesis across a wide range of oceanic irradiances. Similar results in a pennate diatom, dinoflagellate, and coccolithophore, but not green or red microalgae, imply the co-option of phagocytic VHA activity into a carbon-concentrating mechanism (CCM) is common to secondary endosymbiotic phytoplankton. Furthermore, analogous mechanisms in extant photosymbiotic marine invertebrates6–8 provide functional evidence for an adaptive advantage throughout the transition from endosymbiosis to symbiogenesis. Based on the contribution of diatoms to ocean biogeochemical cycles, VHA-mediated enhancement of photosynthesis contributes at least 3.5 Gtons of fixed carbon per year (or 7% of primary production in the ocean), providing an example of a symbiosis-derived evolutionary innovation with global environmental implications. %B Current Biology %P S0960982223006152 %8 may %G eng %U https://linkinghub.elsevier.com/retrieve/pii/S0960982223006152 %R 10.1016/j.cub.2023.05.020 %0 Journal Article %J Marine Micropaleontology %D 2022 %T Coccolith size rules – What controls the size of coccoliths during coccolithogenesis? %A Suchéras-Marx, Baptiste %A Viseur, Sophie %A Walker, Charlotte E. %A Beaufort, Luc %A Probert, Ian %A Bolton, Clara %K Biometry %K coccolith %K coccolithophore %K life cycle %K RCC1216 %K Size variation %X Heterococcoliths are calcite platelets produced inside diploid coccolithophore cells and extruded to form a covering on the cell surface called a coccosphere. The size of coccoliths is an important parameter sometimes used to identify species, and it is observed to be influenced in extant species by abiotic parameters (e.g., CO2, light). However, the variable distribution of coccolith sizes occurring within a single coccosphere questions the mechanisms controlling coccolith size. A relationship between cell/coccosphere size and mean coccolith size was previously identified, called the “coccolithophore size rules”. In this study, we query the mechanisms controlling the size of a coccolith during coccolithogenesis. A culture experiment on Gephyrocapsa huxleyi strain RCC1216 shows that coccolithogenesis occurs during the cell growth G1 interphase and newly produced coccoliths get bigger as the cell grows. These observations provide parameters for the development of two numerical models used to simulate the coccolith size distribution within a coccolithophore population. Neither model can accurately reproduce an empirical monoclonal coccolith size distribution, indicating that additional factors influence coccolith size. According to our results, coccolith size is only clearly related to cell size at the time of its formation. We confirm that application of the coccolithophore size rules model should be limited to inferring average cell dimensions from (fossil) coccolith biometry, and that comparisons are valid only in multipopulational studies. The coccolith size rule model – the constraining effect of coccolith production during G1 interphase cell growth on coccolith size – proposed here is applicable only for some placolith-forming species. %B Marine Micropaleontology %V 170 %P 102080 %G eng %U https://www.sciencedirect.com/science/article/pii/S0377839821001213 %R 10.1016/j.marmicro.2021.102080 %0 Journal Article %J Frontiers in Microbiology %D 2022 %T Comparative Thermophysiology of Marine Synechococcus CRD1 Strains Isolated From Different Thermal Niches in Iron-Depleted Areas %A Ferrieux, Mathilde %A Dufour, Louison %A Doré, Hugo %A Ratin, Morgane %A Guéneuguès, Audrey %A Chasselin, Léo %A Marie, Dominique %A Rigaut-jalabert, Fabienne %A Le Gall, Florence %A Sciandra, Théo %A Monier, Garance %A Hoebeke, Mark %A Corre, Erwan %A Xia, Xiaomin %A Liu, Hongbin %A Scanlan, David J. %A Partensky, Frédéric %A Garczarek, Laurence %K RCC2374 %K RCC2385 %K RCC2533 %K RCC2534 %K RCC2571 %K RCC515 %K rcc539 %K rcc791 %X Marine Synechococcus cyanobacteria are ubiquitous in the ocean, a feature likely related to their extensive genetic diversity. Amongst the major lineages, clades I and IV preferentially thrive in temperate and cold, nutrient-rich waters, whilst clades II and III prefer warm, nitrogen or phosphorus-depleted waters. The existence of such cold (I/IV) and warm (II/III) thermotypes is corroborated by physiological characterization of representative strains. A fifth clade, CRD1, was recently shown to dominate the Synechococcus community in iron-depleted areas of the world ocean and to encompass three distinct ecologically significant taxonomic units (ESTUs CRD1A-C) occupying different thermal niches, suggesting that distinct thermotypes could also occur within this clade. Here, using comparative thermophysiology of strains representative of these three CRD1 ESTUs we show that the CRD1A strain MITS9220 is a warm thermotype, the CRD1B strain BIOS-U3-1 a cold temperate thermotype, and the CRD1C strain BIOS-E4-1 a warm temperate stenotherm. Curiously, the CRD1B thermotype lacks traits and/or genomic features typical of cold thermotypes. In contrast, we found specific physiological traits of the CRD1 strains compared to their clade I, II, III, and IV counterparts, including a lower growth rate and photosystem II maximal quantum yield at most temperatures and a higher turnover rate of the D1 protein. Together, our data suggests that the CRD1 clade prioritizes adaptation to low-iron conditions over temperature adaptation, even though the occurrence of several CRD1 thermotypes likely explains why the CRD1 clade as a whole occupies most iron-limited waters. %B Frontiers in Microbiology %V 13 %G eng %U https://www.frontiersin.org/article/10.3389/fmicb.2022.893413 %R 10.3389/fmicb.2022.893413 %0 Journal Article %J Journal of Marine Science and Engineering %D 2022 %T Diversity and Evolution of Mamiellophyceae: Early-Diverging Phytoplanktonic Green Algae Containing Many Cosmopolitan Species %A Yung, Charmaine C. M. %A Rey Redondo, Elvira %A Sanchez, Frédéric %A Yau, Sheree %A Piganeau, Gwenael %K Biogeography %K evolution %K genomics %K mamiellophyceae %K metagenomics %K microalgae–virus interactions %K phycoDNAvirus %K RCC809 %X The genomic revolution has bridged a gap in our knowledge about the diversity, biology and evolution of unicellular photosynthetic eukaryotes, which bear very few discriminating morphological features among species from the same genus. The high-quality genome resources available in the class Mamiellophyceae (Chlorophyta) have been paramount to estimate species diversity and screen available metagenomic data to assess the biogeography and ecological niches of different species on a global scale. Here we review the current knowledge about the diversity, ecology and evolution of the Mamiellophyceae and the large double-stranded DNA prasinoviruses infecting them, brought by the combination of genomic and metagenomic analyses, including 26 metabarcoding environmental studies, as well as the pan-oceanic GOS and the Tara Oceans expeditions. %B Journal of Marine Science and Engineering %V 10 %P 240 %8 feb %G eng %U https://www.mdpi.com/2077-1312/10/2/240 %R 10.3390/jmse10020240 %0 Journal Article %J Data in Brief %D 2022 %T Draft genome assembly and sequencing dataset of the marine diatom Skeletonema costatum RCC75 %A Sorokina, Maria %A Barth, Emanuel %A Zulfiqar, Mahnoor %A Kwantes, Michiel %A Pohnert, Georg %A Steinbeck, Christoph %K Algal genome %K BACILLARIOPHYCEAE %K diatoms %K genome sequencing %K Illumina sequencing %K PacBio sequencing %K RCC75 %X Diatoms (Bacillariophyceae) are a major constituent of the phytoplankton and have a universally recognized ecological importance. Between 1,000 and 1,300 diatom genera have been described in the literature, but only 10 nuclear genomes have been published and made available to the public up to date. Skeletonema costatum is a cosmopolitan marine diatom, principally occurring in coastal regions, and is one of the most abundant members of the Skeletonema genus. Here we present a draft assembly of the Skeletonema costatum RCC75 genome, obtained from PacBio and Illumina NovaSeq data. This dataset will expand the knowledge of the Bacillariophyceae genetics and contribute to the global understanding of phytoplankton's physiological, ecological, and environmental functioning. %B Data in Brief %P 107931 %8 feb %G eng %U https://www.sciencedirect.com/science/article/pii/S2352340922001433 %R 10.1016/j.dib.2022.107931 %0 Journal Article %J European Journal of Phycology %D 2022 %T Galactolipids of the genus Amphidinium (Dinophyceae): an hypothesis that they are basal to those of other peridinin-containing dinoflagellates %A Leblond, Jeffrey D. %A Elkins, Lindsey C. %A Graeff, Jori E. %A Sabir, Kyra %K Amphidinium %K chloroplast %K Dinoflagellate %K Dinophyceae %K lipid %K RCC1981 %K Testudodinium %X The genus Amphidinium is shown in many phylogenies to be basal to other peridinin-containing, photosynthetic dinoflagellates as one of the first photosynthetic genera to arise after the evolution of heterotrophic genera. As part of our continuing examination of the plastid-associated galactolipids, namely mono- and digalactosyldiacylglycerol (MGDG and DGDG, respectively), in dinoflagellates, we here examine the galactolipid composition of members of the genus Amphidinium. We show that this genus is characterized by an abundance of 20:5(n-3)/18:5(n-3) and 20:5(n-3)/18:4(n-3) forms of MGDG and DGDG (with sn-1/sn-2 regiochemical specificity of fatty acids), but also sometimes with generally lesser amounts of some polyunsaturated C18/C18 forms, thus placing the examined species within a previously identified cluster of C20/C18 MGDG- and DGDG-containing, peridinin-containing dinoflagellates. We also show that Testudodinium testudo, previously known as Amphidinium testudo, conversely falls within a previously identified C18/C18 cluster, indicating a distinct difference in galactolipid biosynthesis capability. While it is likely that further revision of the genus may occur in the future and/or more basal peridinin-containing, photosynthetic genera may be discovered, at the current time Amphidinium is the currently agreed-upon most basal dinoflagellate genus for which isolates are available for biochemical characterization such as what we describe in this paper. Thus, because of the presumed basal position of the genus Amphidinium, we present a hypothesis that its galactolipids currently represent those that are ancestral to other genera of peridinin-containing dinoflagellates, including those within the C18/C18 cluster. %B European Journal of Phycology %P 1–10 %G eng %U https://doi.org/10.1080/09670262.2022.2092215 %R 10.1080/09670262.2022.2092215 %0 Journal Article %J mSystems %D 2022 %T Global Phylogeography of Marine Synechococcus in Coastal Areas Reveals Strong Community Shifts %A Doré, Hugo %A Leconte, Jade %A Guyet, Ulysse %A Breton, Solène %A Farrant, Gregory K. %A Demory, David %A Ratin, Morgane %A Hoebeke, Mark %A Corre, Erwan %A Pitt, Frances D. %A Ostrowski, Martin %A Scanlan, David J. %A Partensky, Frédéric %A Six, Christophe %A Garczarek, Laurence %K RCC1086 %K RCC1695 %K RCC2369 %K rcc2380 %K RCC2553 %K RCC2556 %K RCC2570 %K rcc791 %X Marine Synechococcus comprise a numerically and ecologically prominent phytoplankton group, playing a major role in both carbon cycling and trophic networks in all oceanic regions except in the polar oceans. Despite their high abundance in coastal areas, our knowledge of Synechococcus communities in these environments is based on only a few local studies. Here, we use the global metagenome data set of the Ocean Sampling Day (June 21st, 2014) to get a snapshot of the taxonomic composition of coastal Synechococcus communities worldwide, by recruitment on a reference database of 141 picocyanobacterial genomes, representative of the whole Prochlorococcus, Synechococcus, and Cyanobium diversity. This allowed us to unravel drastic community shifts over small to medium scale gradients of environmental factors, in particular along European coasts. The combined analysis of the phylogeography of natural populations and the thermophysiological characterization of eight strains, representative of the four major Synechococcus lineages (clades I to IV), also brought novel insights about the differential niche partitioning of clades I and IV, which most often co-dominate the Synechococcus community in cold and temperate coastal areas. Altogether, this study reveals several important characteristics and specificities of the coastal communities of Synechococcus worldwide. IMPORTANCE Synechococcus is the second most abundant phytoplanktonic organism on Earth, and its wide genetic diversity allowed it to colonize all the oceans except for polar waters, with different clades colonizing distinct oceanic niches. In recent years, the use of global metagenomics data sets has greatly improved our knowledge of “who is where” by describing the distribution of Synechococcus clades or ecotypes in the open ocean. However, little is known about the global distribution of Synechococcus ecotypes in coastal areas, where Synechococcus is often the dominant phytoplanktonic organism. Here, we leverage the global Ocean Sampling Day metagenomics data set to describe Synechococcus community composition in coastal areas worldwide, revealing striking community shifts, in particular along the coasts of Europe. As temperature appears as an important driver of the community composition, we also characterize the thermal preferenda of 8 Synechococcus strains, bringing new insights into the adaptation to temperature of the dominant Synechococcus clades. %B mSystems %P e00656–22 %G eng %U https://journals.asm.org/doi/full/10.1128/msystems.00656-22 %R 10.1128/msystems.00656-22 %0 Journal Article %J Microbial Ecology %D 2022 %T High-CO2 Levels Rather than Acidification Restrict Emiliania huxleyi Growth and Performance %A Vázquez, Víctor %A León, Pablo %A Gordillo, Francisco J. L. %A Jiménez, Carlos %A Concepción, Iñiguez %A Mackenzie, Kevin %A Bresnan, Eileen %A Segovia, María %K Calcification %K coccolithophores %K Emiliania huxleyi %K Ocean acidification %K pCO2 %K Photochemistry %K phytoplankton %K rcc1226 %K Stress %X The coccolithophore Emiliania huxleyi shows a variety of responses to ocean acidification (OA) and to high-CO2 concentrations, but there is still controversy on differentiating between these two factors when using different strains and culture methods. A heavily calcified type A strain isolated from the Norwegian Sea was selected and batch cultured in order to understand whether acclimation to OA was mediated mainly by CO2 or H+, and how it impacted cell growth performance, calcification, and physiological stress management. Emiliania huxleyi responded differently to each acidification method. CO2-enriched aeration (1200 µatm, pH 7.62) induced a negative effect on the cells when compared to acidification caused by decreasing pH alone (pH 7.60). The growth rates of the coccolithophore were more negatively affected by high pCO2 than by low pH without CO2 enrichment with respect to the control (400 µatm, pH 8.1). High CO2 also affected cell viability and promoted the accumulation of reactive oxygen species (ROS), which was not observed under low pH. This suggests a possible metabolic imbalance induced by high CO2 alone. In contrast, the affinity for carbon uptake was negatively affected by both low pH and high CO2. Photochemistry was only marginally affected by either acidification method when analysed by PAM fluorometry. The POC and PIC cellular quotas and the PIC:POC ratio shifted along the different phases of the cultures; consequently, calcification did not follow the same pattern observed in cell stress and growth performance. Specifically, acidification by HCl addition caused a higher proportion of severely deformed coccoliths, than CO2 enrichment. These results highlight the capacity of CO2 rather than acidification itself to generate metabolic stress, not reducing calcification. %B Microbial Ecology %G eng %U https://doi.org/10.1007/s00248-022-02035-3 %R 10.1007/s00248-022-02035-3 %0 Journal Article %J Ecotoxicology and Environmental Safety %D 2022 %T Impact of salinities, metals and organic compounds found in saline oil & gas produced water on microalgae and cyanobacteria %A Parsy, Aurélien %A Guyoneaud, Rémy %A Lot, Marie-Claire %A Baldoni-Andrey, Patrick %A Périé, Frédéric %A Sambusiti, Cecilia %K RCC4223 %K RCC537 %K rcc752 %X This work evaluates the impact of salinity and the toxicity of some metals and organic compounds commonly found in produced waters on the growth of model photosynthetic organisms. Five strains of marine microalgae and one cyanobacteria (i.e. Dunaliella salina, Nannochloropsis oceanica, Tetraselmis suecica, Picochlorum cos- tavermella, Coccomyxa simplex and Synechococcus rubescens) were tested in microplates as well as the freshwater Chlorella vulgaris selected as reference. Results revealed that D.salina was able to growth at high salinity (up to 135 g.L- 1). Copper was the most toxic metal for all strains (half maximal effective concentration between 0.1 and 10 mg.L- 1) except for D.salina and C.simplex. These two strains were the most resistant to all metals tested. All organic compounds presented half maximal effective concentration above 10 mg.L- 1, none of them being very toxic for the studied microorganisms. P.costavermella and C.simplex were the most resistant strains to organic compounds. Looking at tolerance to salinity, metals and organic compounds, D.salina appeared to be the best choice for biomass production in produced waters. In addition, growths in 80% artificial produced water sup- plemented with f medium confirm the feasibility to use this medium to produce biomass. %B Ecotoxicology and Environmental Safety %V 234 %P 113351 %G eng %U https://linkinghub.elsevier.com/retrieve/pii/S0147651322001919 %R 10.1016/j.ecoenv.2022.113351 %0 Journal Article %J Comptes Rendus. Biologies %D 2022 %T Light-driven processes: key players of the functional biodiversity in microalgae %A Falciatore, Angela %A Bailleul, Benjamin %A Boulouis, Alix %A Bouly, Jean-Pierre %A Bujaldon, Sandrine %A Cheminant-Navarro, Soizic %A Choquet, Yves %A Vitry, Catherine de %A Eberhard, Stephan %A Jaubert, Marianne %A Kuras, Richard %A Lafontaine, Ingrid %A Landier, Sophie %A Selles, Julien %A Vallon, Olivier %A Wostrikoff, Katia %B Comptes Rendus. Biologies %V 345 %P 1–24 %G eng %U https://comptes-rendus.academie-sciences.fr/biologies/articles/10.5802/crbiol.80/ %R 10.5802/crbiol.80 %0 Journal Article %J Phytochemistry %D 2022 %T Metabolic adaptation of diatoms to hypersalinity %A Nikitashina, Vera %A Stettin, Daniel %A Pohnert, Georg %K Diatomic algae %K Hypersalinity stress response %K Osmolytes %K Phaeodactylaceae %K Phaeodactylum tricornutum %K RCC75 %K Skeletonema marinoi %K Skeletonemataceae %K Thalassiosira pseudonana %K Thalassiosiraceae %K Untargeted metabolite profiling %X Microalgae are important primary producers and form the basis for the marine food web. As global climate changes, so do salinity levels that algae are exposed to. A metabolic response of algal cells partly alleviates the resulting osmotic stress. Some metabolites involved in the response are well studied, but the full metabolic implications of adaptation remain unclear. Improved analytical methodology provides an opportunity for additional insight. We can now follow responses to stress in major parts of the metabolome and derive comprehensive charts of the resulting metabolic re-wiring. In this study, we subjected three species of diatoms to high salinity conditions and compared their metabolome to controls in an untargeted manner. The three well-investigated species with sequenced genomes Phaeodactylum tricornutum, Thalassiosira pseudonana, and Skeletonema marinoi were selected for our survey. The microalgae react to salinity stress with common adaptations in the metabolome by amino acid up-regulation, production of saccharides, and inositols. But also species-specific dysregulation of metabolites is common. Several metabolites previously not connected with osmotic stress reactions are identified, including 4-hydroxyproline, pipecolinic acid, myo-inositol, threonic acid, and acylcarnitines. This expands our knowledge about osmoadaptation and calls for further functional characterization of metabolites and pathways in algal stress physiology. %B Phytochemistry %P 113267 %G eng %U https://www.sciencedirect.com/science/article/pii/S0031942222001832 %R 10.1016/j.phytochem.2022.113267 %0 Journal Article %J mBio %D 2022 %T Multiple Photolyases Protect the Marine Cyanobacterium Synechococcus from Ultraviolet Radiation %A Haney, Allissa M. %A Sanfilippo, Joseph E. %A Garczarek, Laurence %A Partensky, Frédéric %A Kehoe, David M. %E Ruby, Edward %K rcc555 %X

Marine cyanobacteria depend on light for photosynthesis, restricting their growth to the photic zone. The upper part of this layer is exposed to strong UV radiation (UVR), a DNA mutagen that can harm these microorganisms. To thrive in UVR-rich waters, marine cyanobacteria employ photoprotection strategies that are still not well defined. Among these are photolyases, light-activated enzymes that repair DNA dimers generated by UVR. Our analysis of genomes of 81 strains of Synechococcus, Cyanobium, and Prochlorococcus isolated from the world’s oceans shows that they possess up to five genes encoding different members of the photolyase/cryptochrome family, including a photolyase with a novel domain arrangement encoded by either one or two separate genes. We disrupted the putative photolyase-encoding genes in Synechococcus sp. strain RS9916 and discovered that each gene contributes to the overall capacity of this organism to survive UVR. Additionally, each conferred increased survival after UVR exposure when transformed into Escherichia coli lacking its photolyase and SOS response. Our results provide the first evidence that this large set of photolyases endows Synechococcus with UVR resistance that is far superior to that of E. coli, but that, unlike for E. coli, these photolyases provide Synechococcus with the vast majority of its UVR tolerance.

%B mBio %V 13 %P e01511–22 %8 aug %G eng %U https://journals.asm.org/doi/10.1128/mbio.01511-22 %R 10.1128/mbio.01511-22 %0 Journal Article %J Frontiers in Microbiology %D 2022 %T The phycoerythrobilin isomerization activity of MpeV in Synechococcus sp. WH8020 is prevented by the presence of a histidine at position 141 within its phycoerythrin-I β-subunit substrate %A Carrigee, Lyndsay A. %A Frick, Jacob P. %A Liu, Xindi %A Karty, Jonathan A. %A Trinidad, Jonathan C. %A Tom, Irin P. %A Yang, Xiaojing %A Dufour, Louison %A Partensky, Frédéric %A Schluchter, Wendy M. %K RCC2437 %K RCC307 %K RCC751 %X Marine Synechococcus efficiently harvest available light for photosynthesis using complex antenna systems, called phycobilisomes, composed of an allophycocyanin core surrounded by rods, which in the open ocean are always constituted of phycocyanin and two phycoerythrin (PE) types: PEI and PEII. These cyanobacteria display a wide pigment diversity primarily resulting from differences in the ratio of the two chromophores bound to PEs, the green-light absorbing phycoerythrobilin and the blue-light absorbing phycourobilin. Prior to phycobiliprotein assembly, bilin lyases post-translationally catalyze the ligation of phycoerythrobilin to conserved cysteine residues on α- or β-subunits, whereas the closely related lyase-isomerases isomerize phycoerythrobilin to phycourobilin during the attachment reaction. MpeV was recently shown in Synechococcus sp. RS9916 to be a lyase-isomerase which doubly links phycourobilin to two cysteine residues (C50 and C61; hereafter C50, 61) on the β-subunit of both PEI and PEII. Here we show that Synechococcus sp. WH8020, which belongs to the same pigment type as RS9916, contains MpeV that demonstrates lyase-isomerase activity on the PEII β-subunit but only lyase activity on the PEI β-subunit. We also demonstrate that occurrence of a histidine at position 141 of the PEI β-subunit from WH8020, instead of a leucine in its counterpart from RS9916, prevents the isomerization activity by WH8020 MpeV, showing for the first time that both the substrate and the enzyme play a role in the isomerization reaction. We propose a structural-based mechanism for the role of H141 in blocking isomerization. More generally, the knowledge of the amino acid present at position 141 of the β-subunits may be used to predict which phycobilin is bound at C50, 61 of both PEI and PEII from marine Synechococcus strains. %B Frontiers in Microbiology %V 13 %P 1011189 %G eng %U https://www.frontiersin.org/articles/10.3389/fmicb.2022.1011189/full %R 10.3389/fmicb.2022.1011189 %0 Journal Article %J The ISME Journal %D 2022 %T Phycosphere pH of unicellular nano- and micro- phytoplankton cells and consequences for iron speciation %A Liu, Fengjie %A Gledhill, Martha %A Tan, Qiao-Guo %A Zhu, Kechen %A Zhang, Qiong %A Salaün, Pascal %A Tagliabue, Alessandro %A Zhang, Yanjun %A Weiss, Dominik %A Achterberg, Eric P. %A Korchev, Yuri %K Biogeochemistry %K Microbial biooceanography %K RCC1 %K rcc1731 %K Water microbiology %X Surface ocean pH is declining due to anthropogenic atmospheric CO2 uptake with a global decline of \textasciitilde0.3 possible by 2100. Extracellular pH influences a range of biological processes, including nutrient uptake, calcification and silicification. However, there are poor constraints on how pH levels in the extracellular microenvironment surrounding phytoplankton cells (the phycosphere) differ from bulk seawater. This adds uncertainty to biological impacts of environmental change. Furthermore, previous modelling work suggests that phycosphere pH of small cells is close to bulk seawater, and this has not been experimentally verified. Here we observe under 140 μmol photons·m−2·s−1 the phycosphere pH of Chlamydomonas concordia (5 µm diameter), Emiliania huxleyi (5 µm), Coscinodiscus radiatus (50 µm) and C. wailesii (100 µm) are 0.11 ± 0.07, 0.20 ± 0.09, 0.41 ± 0.04 and 0.15 ± 0.20 (mean ± SD) higher than bulk seawater (pH 8.00), respectively. Thickness of the pH boundary layer of C. wailesii increases from 18 ± 4 to 122 ± 17 µm when bulk seawater pH decreases from 8.00 to 7.78. Phycosphere pH is regulated by photosynthesis and extracellular enzymatic transformation of bicarbonate, as well as being influenced by light intensity and seawater pH and buffering capacity. The pH change alters Fe speciation in the phycosphere, and hence Fe availability to phytoplankton is likely better predicted by the phycosphere, rather than bulk seawater. Overall, the precise quantification of chemical conditions in the phycosphere is crucial for assessing the sensitivity of marine phytoplankton to ongoing ocean acidification and Fe limitation in surface oceans. %B The ISME Journal %V 16 %P 2329–2336 %8 oct %G eng %U https://www.nature.com/articles/s41396-022-01280-1 %R 10.1038/s41396-022-01280-1 %0 Journal Article %J Marine Drugs %D 2022 %T Scale-Up to Pilot of a Non-Axenic Culture of Thraustochytrids Using Digestate from Methanization as Nitrogen Source %A de la Broise, Denis %A Ventura, Mariana %A Chauchat, Luc %A Guerreiro, Maurean %A Michez, Teo %A Vinet, Thibaud %A Gautron, Nicolas %A Le Grand, Fabienne %A Bideau, Antoine %A Goïc, Nelly Le %A Bidault, Adeline %A Lambert, Christophe %A Soudant, Philippe %K RCC893 %X The production of non-fish based docosahexaenoic acid (DHA) for feed and food has become a critical need in our global context of over-fishing. The industrial-scale production of DHA–rich Thraustochytrids could be an alternative, if costs turned out to be competitive. In order to reduce production costs, this study addresses the feasibility of the non-axenic (non-sterile) cultivation of Aurantiochytrium mangrovei on industrial substrates (as nitrogen and mineral sources and glucose syrup as carbon and energy sources), and its scale-up from laboratory (250 mL) to 500 L cultures. Pilot-scale reactors were airlift cylinders. Batch and fed-batch cultures were tested. Cultures over 38 to 62 h achieved a dry cell weight productivity of 3.3 to 5.5 g.L−1.day−1, and a substrate to biomass yield of up to 0.3. DHA productivity ranged from 10 to 0.18 mg.L−1.day−1. Biomass productivity appears linearly related to oxygen transfer rate. Bacterial contamination of cultures was low enough to avoid impacts on fatty acid composition of the biomass. A specific work on microbial risks assessment (in supplementary files) showed that the biomass can be securely used as feed. However, to date, there is a law void in EU legislation regarding the recycling of nitrogen from digestate from animal waste for microalgae biomass and its usage in animal feed. Overall, the proposed process appears similar to the industrial yeast production process (non-axenic heterotrophic process, dissolved oxygen supply limiting growth, similar cell size). Such similarity could help in further industrial developments. %B Marine Drugs %V 20 %P 499 %8 aug %G eng %U https://www.mdpi.com/1660-3397/20/8/499 %R 10.3390/md20080499 %0 Journal Article %J Journal of Ecology %D 2022 %T Shifts in growth light optima among diatom species support their succession during the spring bloom in the Arctic %A Croteau, D. %A Lacour, T. %A Schiffrine, N. %A Morin, P.-I. %A Forget, M.-H. %A Bruyant, F. %A Ferland, J. %A Lafond, A. %A Campbell, D. A. %A Tremblay, J.-E. %A Babin, M. %A Lavaud, J. %K Arctic Ocean %K diatoms %K Ecophysiology %K photoacclimation %K photoadaptation %K primary production %K RCC2046 %K RCC2278 %K seasonal species succession %K spring bloom %X 1. Diatoms of the Arctic Ocean annually experience extreme changes of light environment linked to photoperiodic cycles and seasonal variations of the snow and sea-ice cover extent and thickness which attenuate light penetration in the water column. Arctic diatom communities exploit this complex seasonal dynamic through a well-documented species succession during spring, beginning in sea-ice and culminating in massive phytoplankton blooms underneath sea-ice and in the marginal ice zone. The pattern of diatom taxa sequentially dominating this succession is relatively well conserved interannually, and taxonomic shifts seem to align with habitat transitions. 2. To understand whether differential photoadaptation strategies among diatom taxa explain these recurring succession sequences, we coupled lab experiments with field work in Baffin Bay at 67.5°N. Based on field data, we selected five diatom species typical of different ecological niches and measured their growth rates under light intensity ranges representative of their natural habitats. To characterize their photoacclimative responses, we sampled pigments and total particulate carbon, and conducted 14C-uptake photosynthesis response curves and variable fluorescence measurements. 3. We documented a gradient in species respective light intensity for maximal growth suggesting divergent light response plasticity, which for the most part align with species sequential dominance. Other photophysiological parameters supported this ecophysiological framing, although contrasts were always clear only between succession endmembers, Nitzschia frigida and Chaetoceros neogracilis. To validate that these photoacclimative responses are representative of in situ dynamics, we compared them to the chlorophyll a-specific light-limited slope (α*) and saturated rate of photosynthesis (P*M), monitored in Baffin Bay on sea-ice and planktonic communities. This complementary approach confirmed that unusual responses in α* and P*M as a function of light history intensity are similar between sentinel sympagic species N. frigida and natural ice-core communities. While no light-history-dependent trends were observed in planktonic communities, their α* and P*M values were in the range of measurements from our monospecific cultures. 4. Synthesis. Our results suggest that Arctic diatoms species photoadaptation strategy is tuned to the light environment of the habitats in which they dominate and indeed drives the seasonal taxonomic succession. %B Journal of Ecology %V n/a %G eng %U http://onlinelibrary.wiley.com/doi/abs/10.1111/1365-2745.13874 %R 10.1111/1365-2745.13874 %0 Journal Article %J Journal of Eukaryotic Microbiology %D 2022 %T Sterols of Testudodinium testudo (formerly Amphidinium testudo): Production of the Δ8(14) sterol gymnodinosterol and chemotaxonomic relationship to the Kareniaceae %A Leblond, Jeffrey D. %A Elkins, Lindsey C. %A Sabir, Kyra %A Graeff, Jori E. %K Amphidinium %K Dinoflagellate %K Dinophyceae %K lipid %K RCC1981 %K sterol %K Testudodinium %X Testudodinium testudo is a peridinin-containing dinoflagellate recently renamed from Amphidinium testudo. While T. testudo has been shown via phylogenetic analysis of small subunit ribosomal RNA genes to reside in a clade separate from the genus Amphidinium, it does possess morphological features similar to Amphidinium sensu stricto. Previous studies of Amphidinium carterae and Amphidinium corpulentum have found the sterols to be enriched in Δ8(14) sterols, such as 4α-methyl-5α-ergosta-8(14),24(28)-dien-3β-ol (amphisterol), uncommon to most other dinoflagellate taxa and thus considered possible biomarkers for the genus Amphidinium. Here, we provide an examination of the sterols of T. testudo and show they are dominated not by amphisterol, but rather by a different Δ8(14) sterol, (24R)-4α-methyl-5α-ergosta-8(14),22-dien-3β-ol (gymnodinosterol), previously thought to be a major sterol only within the Kareniaceae genera Karenia, Karlodinium, and Takayama. Also found to be present at low levels were 4α-methyl-5α-ergosta-8,14,22-trien-3β-ol, a sterol previously observed in Karenia brevis to be an intermediate in the production of gymnodinosterol, and cholesterol, a sterol common to many other dinoflagellates. The presence of gymnodinosterol in T. testudo is the first report of this sterol as the sole major sterol in a dinoflagellate outside of the Kareniaceae. The implication of this chemotaxonomic relationship to the Kareniaceae is discussed. %B Journal of Eukaryotic Microbiology %V n/a %P e12929 %G eng %U http://onlinelibrary.wiley.com/doi/abs/10.1111/jeu.12929 %R 10.1111/jeu.12929 %0 Journal Article %J European Journal of Phycology %D 2022 %T Taxonomic relationship between two small-sized Chaetoceros species (Bacillariophyta): C. tenuissimus and C. salsugineus , and comparison with C. olympicus sp. nov. from Catalan coastal waters (NW Mediterranean) %A Arin, Laura %A Reñé, Albert %A Gallisai, Rachele %A Sarno, Diana %A Garcés, Esther %A Estrada, Marta %K RCC3007 %K RCC3008 %K RCC5795 %X

The majority of species of the highly diverse genus Chaetoceros are described as chain-forming, although several species are described as strictly solitary (such as C. tenuissimus) or having an alternate solitary and a chain-forming phase during their life history (such as C. salsugineus). In this study, the diversity of small forms of Chaetoceros from the NW Mediterranean coastal waters was explored through the morphological and molecular characterization of four different strains belonging to two distinct species. Based on their morphology, three of the strains were identified as C. salsugineus (Takano, 1983). The SSU and LSU rDNA sequences represented the first available for well-characterized C. salsugineus strains and were 96.6–100% similar to publicly available C. tenuissimus (Meunier, 1913) sequences. Both species share the same morphological features, such as setae and ultrastructure of the valves, as well as the rimoportula characteristics. In addition, the morphology of the solitary form of C. salsugineus matched with that of C. tenuissimus. Here, we propose the two species as synonyms (the name C. tenuissimus prevailing as it has priority for this taxon), emend the original description and designate an epitype. The fourth strain was identified as C. olympicus sp. nov., a new species, which alternates solitary and chain-forming forms within its life history. The main differential characteristics of this species are the absence of rimoportula both in terminal and intercalary valves, the setae ultrastructure, which is thin and circular in cross-section with a few, slightly twisted, rows of small rectangular poroids and some spirally arranged spines, and the morphology of the resting spores, with primary valve vaulted and covered with short to medium-sized spines, and secondary valve smaller, rounded and smooth. A comparison of C. tenuissimus and C. olympicus with other species as well as information on their life cycle and ecology is also provided.

%B European Journal of Phycology %V 57 %P 277–296 %G eng %U https://www.tandfonline.com/doi/full/10.1080/09670262.2021.1966838 %R 10.1080/09670262.2021.1966838 %0 Journal Article %J Microorganisms %D 2022 %T Temperature Affects the Biological Control of Dinoflagellates by the Generalist Parasitoid Parvilucifera rostrata %A Schmitt, Matthew %A Telusma, Aaron %A Bigeard, Estelle %A Guillou, Laure %A Alves-de-Souza, Catharina %K dinoflagellate blooms %K functional response %K parasitic control %K RCC2800 %K RCC2823 %K RCC2982 %K RCC3018 %K RCC4398 %K temperature effect %X The increase in emerging harmful algal blooms in the last decades has led to an extensive concern in understanding the mechanisms behind these events. In this paper, we assessed the growth of two blooming dinoflagellates (Alexandrium minutum and Heterocapsa triquetra) and their susceptibility to infection by the generalist parasitoid Parvilucifera rostrata under a temperature gradient. The growth of the two dinoflagellates differed across a range of temperatures representative of the Penzé Estuary (13 to 22 °C) in early summer. A. minutum growth increased across this range and was the highest at 19 and 22 °C, whereas H. triquetra growth was maximal at intermediate temperatures (15–18 °C). Interestingly, the effect of temperature on the parasitoid infectivity changed depending on which host dinoflagellate was infected with the dinoflagellate responses to temperature following a positive trend in A. minutum (higher infections at 20–22 °C) and a unimodal trend in H. triquetra (higher infections at 18 °C). Low temperatures negatively affected parasitoid infections in both hosts (i.e., “thermal refuge”). These results demonstrate how temperature shifts may not only affect bloom development in microalgal species but also their control by parasitoids. %B Microorganisms %V 10 %P 385 %G eng %U https://www.mdpi.com/2076-2607/10/2/385 %R 10.3390/microorganisms10020385 %0 Journal Article %J Plant Science %D 2022 %T TOR signaling in the green picoalga Ostreococcus tauri %A Caló, Gonzalo %A De Marco, María Agustina %A Salerno, Graciela Lidia %A Martínez-Noël, Giselle María Astrid %K Carbon reserves %K Green algae %K Growth %K Nitrogen deprivation %K RCC745 %K TOR inhibitors %K TOR kinase %X Target of rapamycin (TOR) is a master regulator that controls growth and metabolism by integrating external and internal signals. Although there was a great progress in the study of TOR in plants and in the model alga Chlamydomonas, scarce data are available in other green algae. Thus, in this work we studied TOR signaling in Ostreococcus tauri, the smallest free-living eukaryote described to date. This picoalga is particularly important because it has a key site at the base of the green lineage and is part of the marine phytoplankton, contributing to global photosynthesis. We investigated OtTOR complex in silico and experimentally, by using first- and second-generation TOR inhibitors, such as rapamycin and PP242. We analyzed the effect of TOR down-regulation on cell growth and on the accumulation of carbon reserves. The results showed that O. tauri responds to TOR inhibitors more similarly to plants than to Chlamydomonas, being PP242 a valuable tool to study this pathway. Besides, Ottor expression analysis revealed that the kinase is dynamically regulated under nutritional stress. Our data indicate that TOR signaling is conserved in O. tauri and we propose this alga as a good and simple model for studying TOR kinase and its regulation. %B Plant Science %V 323 %P 111390 %8 oct %G eng %U https://www.sciencedirect.com/science/article/pii/S016894522200214X %R 10.1016/j.plantsci.2022.111390 %0 Journal Article %J Science of The Total Environment %D 2022 %T Trace metals exposure in three different coastal compartments show specific morphological and reproductive traits across generations in a sentinel copepod %A Das, Shagnika %A Souissi, Anissa %A Ouddane, Baghdad %A Hwang, Jiang-Shiou %A Souissi, Sami %K RCC1537 %X The effect of exposure from several compartments of the environment at the level of individuals were rarely investigated. This study reports the effect of contaminants from varied compartments like sediment resuspension, elutriation from resuspended sediment (extract) and seawater spiked trace metal mixtures (TM) on morphological and reproductive traits of the pelagic bioindicator copepod Eurytemora affinis. At the population level of E. affinis, lowest survival was observed in dissolved exposures (TM and extract) in the first generation (G1), showing some adaptation in the second generation (G2). An opposite trend for resuspended sediment showed higher sensitivity in survival at G2. At the individual level, prosome length and volume proved to be sensitive parameters for resuspended sediments, whereas clutch size and egg diameter were more sensitive to TM and extract. Although the generation of decontamination (G3, no exposure), showed a significant recovery at the population level (survival % along with clutch size) of E. affinis exposed to resuspended sediment, morphological characteristics like prosome length and volume showed no such recovery (lower than control, p <0.05). To the contrary, dissolved exposure showed no significant recovery from G1 to G3 on neither survival %, clutch size, egg diameter, prosome volume, but an increase of prosome length (p <0.05). Such tradeoffs in combatting the stress from varied sources of toxicity was observed in all exposures, from G1 to G3. The number of lipid droplets inside the body cavity of E. affinis showed a significant positive correlation with trace metal bioaccumulation (p <0.01) along with a negative correlation (p <0.05) with survival and clutch size in each treatment. This confirms the inability of copepods to utilize lipids under stressful conditions. Our study tenders certain morphological and reproductive markers that show specificity to different compartments of exposure, promising an advantage in risk assessment and fish feed studies. %B Science of The Total Environment %P 160378 %8 nov %G eng %U https://linkinghub.elsevier.com/retrieve/pii/S0048969722074800 %R 10.1016/j.scitotenv.2022.160378 %0 Journal Article %J Frontiers in Plant Science %D 2021 %T Altitudinal Zonation of Green Algae Biodiversity in the French Alps %A Stewart, Adeline %A Rioux, Delphine %A Boyer, Fréderic %A Gielly, Ludovic %A Pompanon, François %A Saillard, Amélie %A Thuiller, Wilfried %A Valay, Jean-Gabriel %A Maréchal, Éric %A Coissac, Eric %K rcc %K RCC1055 %K RCC130 %K RCC1563 %K RCC2501 %K RCC2960 %K RCC3402 %K RCC443 %K RCC4743 %K RCC537 %K RCC581 %K RCC6 %K RCC7 %K RCC891 %X Mountain environments are marked by an altitudinal zonation of habitat types. They are home to a multitude of terrestrial green algae, who have to cope with abiotic conditions specific to high elevation, e.g., high UV irradiance, alternating desiccation, rain and snow precipitations, extreme diurnal variations in temperature and chronic scarceness of nutrients. Even though photosynthetic green algae are primary producers colonizing open areas and potential markers of climate change, their overall biodiversity in the Alps has been poorly studied so far, in particular in soil, where algae have been shown to be key components of microbial communities. Here, we investigated whether the spatial distribution of green algae followed the altitudinal zonation of the Alps, based on the assumption that algae settle in their preferred habitats under the pressure of parameters correlated with elevation. We did so by focusing on selected representative elevational gradients at distant locations in the French Alps, where soil samples were collected at different depths. Soil was considered as either a potential natural habitat or temporary reservoir of algae. We showed that algal DNA represented a relatively low proportion of the overall eukaryotic diversity as measured by a universal Eukaryote marker. We designed two novel green algae metabarcoding markers to amplify the Chlorophyta phylum and its Chlorophyceae class, respectively. Using our newly developed markers, we showed that elevation was a strong correlate of species and genus level distribution. Altitudinal zonation was thus determined for about fifty species, with proposed accessions in reference databases. In particular, Planophila laetevirens and Bracteococcus ruber related species as well as the snow alga Sanguina genus were only found in soil starting at 2,000 m above sea level. Analysis of environmental and bioclimatic factors highlighted the importance of pH and nitrogen/carbon ratios in the vertical distribution in soil. Capacity to grow heterotrophically may determine the Trebouxiophyceae over Chlorophyceae ratio. The intensity of freezing events (freezing degree days), proved also determinant in Chlorophyceae distribution. Guidelines are discussed for future, more robust and precise analyses of environmental algal DNA in mountain ecosystems and address green algae species distribution and dynamics in response to environmental changes. %B Frontiers in Plant Science %V 12 %P 1066 %G eng %U https://www.frontiersin.org/article/10.3389/fpls.2021.679428 %R 10.3389/fpls.2021.679428 %0 Journal Article %J Scientific Reports %D 2021 %T Annual phytoplankton dynamics in coastal waters from fildes bay, western antarctic peninsula %A Trefault, Nicole %A de la Iglesia, Rodrigo %A Moreno-Pino, Mario %A Lopes dos Santos, Adriana %A Gérikas Ribeiro, Catherine %A Parada-Pozo, Génesis %A Cristi, Antonia %A Marie, Dominique %A Vaulot, Daniel %K RCC2265 %K RCC2289 %K RCC4582 %K RCC4586 %K RCC5152 %X Year-round reports of phytoplankton dynamics in the West Antarctic Peninsula are rare and mainly limited to microscopy and/or pigment-based studies. We analyzed the phytoplankton community from coastal waters of Fildes Bay in the West Antarctic Peninsula between January 2014 and 2015 using metabarcoding of the nuclear and plastidial 18/16S rRNA gene from both size-fractionated and flow cytometry sorted samples. Overall 14 classes of photosynthetic eukaryotes were present in our samples with the following dominating: Bacillariophyta (diatoms), Pelagophyceae and Dictyochophyceae for division Ochrophyta, Mamiellophyceae and Pyramimonadophyceae for division Chlorophyta, Haptophyta and Cryptophyta. Each metabarcoding approach yielded a different image of the phytoplankton community with for example Prymnesiophyceae more prevalent in plastidial metabarcodes and Mamiellophyceae in nuclear ones. Diatoms were dominant in the larger size fractions and during summer, while Prymnesiophyceae and Cryptophyceae were dominant in colder seasons. Pelagophyceae were particularly abundant towards the end of autumn (May). In addition of Micromonas polaris and Micromonas sp. clade B3, both previously reported in Arctic waters, we detected a new Micromonas 18S rRNA sequence signature, close to, but clearly distinct from M. polaris , which potentially represents a new clade specific of the Antarctic. These results highlight the need for complementary strategies as well as the importance of year-round monitoring for a comprehensive description of phytoplankton communities in Antarctic coastal waters. %B Scientific Reports %V 11 %P 1368 %8 dec %G eng %U http://biorxiv.org/content/early/2020/10/27/2020.10.27.356600.abstract http://www.nature.com/articles/s41598-020-80568-8 %R 10.1038/s41598-020-80568-8 %0 Journal Article %J Scientific Reports %D 2021 %T Bacteria enhance the production of extracellular polymeric substances by the green dinoflagellate Lepidodinium chlorophorum %A Roux, Pauline %A Siano, Raffaele %A Collin, Karine %A Bilien, Gwenael %A Sinquin, Corinne %A Marchand, Laetitia %A Zykwinska, Agata %A Delbarre-Ladrat, Christine %A Schapira, Mathilde %K RCC1489 %X High biomasses of the marine dinoflagellate Lepidodinium chlorophorum cause green seawater discolorations along Southern Brittany (NE Atlantic, France). The viscosity associated to these phenomena has been related to problems in oyster cultivation. The harmful effect of L. chlorophorum might originate from the secretion of Extracellular Polymeric Substances (EPS). To understand whether the EPS are produced by L. chlorophorum or its associated bacteria, or if they are a product of their interaction, batch cultures were performed under non-axenic and pseudo-axenic conditions for three strains. Maximum dinoflagellate cell abundances were observed in pseudo-axenic cultures. The non-sinking fraction of polymers (Soluble Extracellular Polymers, SEP), mainly composed of proteins and the exopolysaccharide sulphated galactan, slightly increased in pseudo-axenic cultures. The amount of Transparent Exopolymer Particles (TEP) per cell increased under non-axenic conditions. Despite the high concentrations of Particulate Organic Carbon (POC) measured, viscosity did not vary. These results suggest that the L. chlorophorum-bacteria interaction could have a detrimental consequence on the dinoflagellate, translating in a negative effect on L. chlorophorum growth, as well as EPS overproduction by the dinoflagellate, at concentrations that should not affect seawater viscosity. %B Scientific Reports %V 11 %P 1–15 %G eng %U http://www.nature.com/articles/s41598-021-84253-2 %R 10.1038/s41598-021-84253-2 %0 Generic %D 2021 %T Combining Nanopore and Illumina Sequencing Permits Detailed Analysis of Insertion Mutations and Structural Variations Produced by PEG-Mediated Transformation in Ostreococcus tauri %A Thomy, Julie %A Sanchez, Frédéric %A Gut, Marta %A Cruz, Fernando %A Alioto, Tyler %A Piganeau, Gwenael %A Grimsley, Nigel %A Yau, Sheree %K RCC1115 %X Ostreococcus tauri is a simple unicellular green alga representing an ecologically important group of phytoplankton in oceans worldwide. Modern molecular techniques must be developed in order to understand the mechanisms that permit adaptation of microalgae to their environment. We present for the first time in O. tauri a detailed characterization of individual genomic integration events of foreign DNA of plasmid origin after PEG-mediated transformation. Vector integration appears to be random, occurring mainly at a single locus, and thus confirming the utility of this technique for insertional mutagenesis. While the mechanism of double-stranded DNA repair in the O. tauri model remains to be elucidated, we clearly demonstrate by genome resequencing that the integration of the vector leads to frequent structural variations (deletions/insertions and duplications) and some chromosomal rearrangements in the genome at the insertion loci, and often within the vector sequence itself. From these observations, we speculate that a non-homologous end joining-like mechanism is required during random insertion events, as described in plants and other freshwater algal models. PEG-mediated transformation is therefore a promising molecular biology tool, not only for functional genomic studies, but also for biotechnological research in ecologically important marine algae. %I LIFE SCIENCES %8 feb %G eng %U https://www.preprints.org/manuscript/202102.0506/v1 %9 preprint %R 10.20944/preprints202102.0506.v1 %0 Journal Article %J Cells %D 2021 %T Combining Nanopore and Illumina Sequencing Permits Detailed Analysis of Insertion Mutations and Structural Variations Produced by PEG-Mediated Transformation in Ostreococcus tauri %A Thomy, Julie %A Sanchez, Frédéric %A Gut, Marta %A Cruz, Fernando %A Alioto, Tyler %A Piganeau, Gwenael %A Grimsley, Nigel %A Yau, Sheree %K RCC1115 %K RCC7079 %K RCC7080 %K RCC7081 %K RCC7082 %K RCC7083 %K RCC7084 %K RCC7085 %X Ostreococcus tauri is a simple unicellular green alga representing an ecologically important group of phytoplankton in oceans worldwide. Modern molecular techniques must be developed in order to understand the mechanisms that permit adaptation of microalgae to their environment. We present for the first time in O. tauri a detailed characterization of individual genomic integration events of foreign DNA of plasmid origin after PEG-mediated transformation. Vector integration occurred randomly at a single locus in the genome and mainly as a single copy. Thus, we confirmed the utility of this technique for insertional mutagenesis. While the mechanism of double-stranded DNA repair in the O. tauri model remains to be elucidated, we clearly demonstrate by genome resequencing that the integration of the vector leads to frequent structural variations (deletions/insertions and duplications) and some chromosomal rearrangements in the genome at the insertion loci. Furthermore, we often observed variations in the vector sequence itself. From these observations, we speculate that a nonhomologous end-joining-like mechanism is employed during random insertion events, as described in plants and other freshwater algal models. PEG-mediated transformation is therefore a promising molecular biology tool, not only for functional genomic studies, but also for biotechnological research in this ecologically important marine alga. %B Cells %V 10 %P 664 %G eng %U https://www.mdpi.com/2073-4409/10/3/664 %R 10.3390/cells10030664 %0 Journal Article %J Ecological Modelling %D 2021 %T cyanoFilter: An R package to identify phytoplankton populations from flow cytometry data using cell pigmentation and granularity %A Olusoji, Oluwafemi D. %A Spaak, Jurg W. %A Holmes, Mark %A Neyens, Thomas %A Aerts, Marc %A De Laender, Frederik %K Ecology %K flow cytometry %K Gating %K phytoplankton %K RCC2375 %K rcc2380 %K RCC2434 %K RCC2555 %K Software %X Flow cytometry is often employed in ecology to measure traits and population size of bacteria and phytoplankton. This technique allows measuring millions of particles in a relatively small amount of time. However, distinguishing between different populations is not a straightforward task. Gating is a process in the identification of particles measured in flow cytometry. Gates can either be created manually using known characteristics of these particles, or by using automated clustering techniques. Available automated techniques implemented in statistical packages for flow cytometry are primarily developed for medicinal applications, while only two exist for phytoplankton. cyanoFilter is an R package built to identify phytoplankton populations from flow cytometry data. The package also integrates gating functions from two other automated algorithms. It also provides a gating accuracy test function that can be used to determine the accuracy of a desired gating function if monoculture flowcytometry data is available. The central algorithm in the package exploits observed pigmentation and granularity of phytoplankton cells. We demonstrate how its performance depends on strain similarity, using a model system of six cyanobacteria strains. Using the same system, we compare the performance of the central gating function in the package to similar functions in other packages. %B Ecological Modelling %V 460 %P 109743 %G eng %U https://www.sciencedirect.com/science/article/pii/S030438002100291X %R 10.1016/j.ecolmodel.2021.109743 %0 Journal Article %J Proceedings of the National Academy of Sciences %D 2021 %T Cytoklepty in the plankton: A host strategy to optimize the bioenergetic machinery of endosymbiotic algae %A Uwizeye, Clarisse %A Brisbin, Margaret Mars %A Gallet, Benoit %A Chevalier, Fabien %A LeKieffre, Charlotte %A Schieber, Nicole L. %A Falconet, Denis %A Wangpraseurt, Daniel %A Schertel, Lukas %A Stryhanyuk, Hryhoriy %A Musat, Niculina %A Mitarai, Satoshi %A Schwab, Yannick %A Finazzi, Giovanni %A Decelle, Johan %K 3D electron microscopy %K oceanic plankton %K Photosynthesis %K rcc %K rcc1383 %K single-cell transcriptomics %K symbiosis %X Endosymbioses have shaped the evolutionary trajectory of life and remain ecologically important. Investigating oceanic photosymbioses can illuminate how algal endosymbionts are energetically exploited by their heterotrophic hosts and inform on putative initial steps of plastid acquisition in eukaryotes. By combining three-dimensional subcellular imaging with photophysiology, carbon flux imaging, and transcriptomics, we show that cell division of endosymbionts (Phaeocystis) is blocked within hosts (Acantharia) and that their cellular architecture and bioenergetic machinery are radically altered. Transcriptional evidence indicates that a nutrient-independent mechanism prevents symbiont cell division and decouples nuclear and plastid division. As endosymbiont plastids proliferate, the volume of the photosynthetic machinery volume increases 100-fold in correlation with the expansion of a reticular mitochondrial network in close proximity to plastids. Photosynthetic efficiency tends to increase with cell size, and photon propagation modeling indicates that the networked mitochondrial architecture enhances light capture. This is accompanied by 150-fold higher carbon uptake and up-regulation of genes involved in photosynthesis and carbon fixation, which, in conjunction with a ca.15-fold size increase of pyrenoids demonstrates enhanced primary production in symbiosis. Mass spectrometry imaging revealed major carbon allocation to plastids and transfer to the host cell. As in most photosymbioses, microalgae are contained within a host phagosome (symbiosome), but here, the phagosome invaginates into enlarged microalgal cells, perhaps to optimize metabolic exchange. This observation adds evidence that the algal metamorphosis is irreversible. Hosts, therefore, trigger and benefit from major bioenergetic remodeling of symbiotic microalgae with potential consequences for the oceanic carbon cycle. Unlike other photosymbioses, this interaction represents a so-called cytoklepty, which is a putative initial step toward plastid acquisition. %B Proceedings of the National Academy of Sciences %V 118 %8 jul %G eng %U https://www.pnas.org/content/118/27/e2025252118 %R 10.1073/pnas.2025252118 %0 Journal Article %J Chemistry Proceedings %D 2021 %T Detection of Alexandrium minutum dinoflagellate in environ- mental samples using electrochemical genosensor %A Morais, Stephanie L %A Barros, Piedade %A Santos, Marlene %A Delerue-Matos, Cristina %A Gomes, Andreia C %A Barroso, M Fátima %K ? No DOI found %K RCC3029 %X Dinoflagellates are aquatic microorganisms that inhabit both salt and fresh waters. These microorganisms are mostly harmless, however, under certain conditions, some species rapidly reproduce forming water blooms that not only discolor the waters but also compromise the health of every organism in the vicinity, as some dinoflagellates produce potent toxins deemed unsafe for human health (e.g. Alexandrium minutum). In this work, a disposable electrochemical genosensor for the detection of the toxic dinoflagellate Alexandrium minutum was developed. The analytical platform methodology consisted in a sandwich format heterogeneous hybridization of complementary DNA sequences assay. The 70 bp A. minutum-specific targeting probe, the 45 bp fluorescein isothiocyanate-labelled signaling DNA probe and the 25 bp thiolated-DNA-capture probe were designed, after analyzing public databases. To maximize the complementary DNA hybridization and to avoid the formation of strong secondary structures, a mixed mercaptohexanol (MCH) and self-assembled monolayer (SAM) A. minutum-specific DNA-capture probe was immobilized onto disposable screen-printed gold electrodes (SPGE). Using chronoamperometric measurements, the enzymatic amplification of the electrochemical signal was obtained with a concentration range from 0.12 to 1.0 nM, a LD of 24.78 pM with a RSD < 5.2 %. This electrochemical genosensor was successfully applied to the selective analysis of the targeted A. minutum specific region of denatured genomic DNA, extracted from toxic dinoflagellates present in the Atlantic Ocean. %B Chemistry Proceedings %P 7 %G eng %0 Journal Article %J ISME Communications %D 2021 %T Dinophyceae can use exudates as weapons against the parasite Amoebophrya sp. (Syndiniales) %A Long, Marc %A Marie, Dominique %A Szymczak, Jeremy %A Toullec, Jordan %A Bigeard, Estelle %A Sourisseau, Marc %A Le Gac, Mickaël %A Guillou, Laure %A Jauzein, Cécile %K microbial ecology %K Plant ecology %K rcc %K RCC1627 %K RCC4383 %K RCC4714 %K RCC749 %K Water microbiology %X Parasites in the genus Amoebophrya sp. infest dinoflagellate hosts in marine ecosystems and can be determining factors in the demise of blooms, including toxic red tides. These parasitic protists, however, rarely cause the total collapse of Dinophyceae blooms. Experimental addition of parasite-resistant Dinophyceae (Alexandrium minutum or Scrippsiella donghaienis) or exudates into a well-established host-parasite coculture (Scrippsiella acuminata-Amoebophrya sp.) mitigated parasite success and increased the survival of the sensitive host. This effect was mediated by waterborne molecules without the need for a physical contact. The strength of the parasite defenses varied between dinoflagellate species, and strains of A. minutum and was enhanced with increasing resistant host cell concentrations. The addition of resistant strains or exudates never prevented the parasite transmission entirely. Survival time of Amoebophrya sp. free-living stages (dinospores) decreased in presence of A. minutum but not of S. donghaienis. Parasite progeny drastically decreased with both species. Integrity of the dinospore membrane was altered by A. minutum, providing a first indication on the mode of action of anti-parasitic molecules. These results demonstrate that extracellular defenses can be an effective strategy against parasites that protects not only the resistant cells producing them, but also the surrounding community. %B ISME Communications %V 1 %P 1–10 %G eng %U http://www.nature.com/articles/s43705-021-00035-x %R 10.1038/s43705-021-00035-x %0 Journal Article %J Frontiers in Marine Science %D 2021 %T Effects of Epibiotic Diatoms on the Productivity of the Calanoid Copepod Acartia tonsa (Dana) in Intensive Aquaculture Systems %A Pan, Yen-Ju %A Wang, Wei-Lung %A Hwang, Jiang-Shiou %A Souissi, Sami %K rcc %K RCC350 %X We evaluated here the effects of the epibiotic diatom Tabularia sp. on the productivity of the calanoid copepod Acartia tonsa (Dana) for assessing their risk on copepod intensive aquaculture industry for the provision of live feed. In the first experiment, uninfested and intensively infested females were cultivated individually for the assessment of egg production. Intensively infested females appeared to have a significantly lower egg production (5.0–9.0 eggs/female/d) than uninfested females (22.0–26.0 eggs/female/d) during 5 consecutive days. In the second experiment, effects of culture densities on diatom epibiosis were investigated in 9 L cultures at three different densities (200, 400, and 600 ind. L–1). Another culture at higher volume (250 L) and lowest density (200 ind. L–1) was also carried out to test the effect of culture volume on diatom epibiosis. The infestation rate (%), infestation intensity (ratio of surface diatom coverage levels, classified as levels 0–3) and daily egg harvest rate (number of harvested eggs per day per liter) were evaluated among the four culture populations. The copepods had higher infestation rate (53.69–60.14%) and intensity rate (high ratios at level 2 and 3) when the densities were increased from 200 ind./L to 400 and 600 ind./L. Although egg harvest increased with increasing culture density, it seemed that the diatom-infested A. tonsa population reach a saturated egg production when the density was higher than 400 ind./L. Nevertheless, the differences of culture volumes (250 and 9 L) appeared to be not to have any effect when the copepods were cultivated at the same density (200 ind./L). This study reveals for the first time that the epibiosis of the diatom Tabularia sp. reduces the individual egg production, and egg harvest rate in high-density culture of the copepod A. tonsa. Our findings implicate that diatom epibiosis should be avoid in copepod intensive culture systems. %B Frontiers in Marine Science %V 8 %P 1386 %G eng %U https://www.frontiersin.org/article/10.3389/fmars.2021.728779 %R 10.3389/fmars.2021.728779 %0 Journal Article %J Genome Biology and Evolution %D 2021 %T Evolutionary Genomics of Sex-Related Chromosomes at the Base of the Green Lineage %A Benites, Luis Felipe %A Bucchini, François %A Sanchez-Brosseau, Sophie %A Grimsley, Nigel %A Vandepoele, Klaas %A Piganeau, Gwenael %E Wolfe, Kenneth %K RCC1105 %K RCC1115 %K RCC2590 %K RCC299 %K rcc3401 %K RCC4221 %K RCC809 %K RCC834 %X Although sex is now accepted as a ubiquitous and ancestral feature of eukaryotes, direct observation of sex is still lacking in most unicellular eukaryotic lineages. Evidence of sex is frequently indirect and inferred from the identification of genes involved in meiosis from whole genome data and/or the detection of recombination signatures from genetic diversity in natural populations. In haploid unicellular eukaryotes, sex-related chromosomes are named mating-type (MTs) chromosomes and generally carry large genomic regions where recombination is suppressed. These regions have been characterized in Fungi and Chlorophyta and determine gamete compatibility and fusion. Two candidate MTþ and MTÀ alleles, spanning 450–650 kb, have recently been described in Ostreococcus tauri, a marine phytoplanktonic alga from the Mamiellophyceae class, an early diverging branch in the green lineage. Here, we investigate the architecture and evolution of these candidate MTþ and MTÀ alleles. We analyzed the phylogenetic profile and GC content of MT gene families in eight different genomes whose divergence has been previously estimated at up to 640 Myr, and found evidence that the divergence of the two MT alleles predates speciation in the Ostreococcus genus. Phylogenetic profiles of MT transspecific polymorphisms in gametologs disclosed candidate MTs in two additional species, and possibly a third. These Mamiellales MT candidates are likely to be the oldest mating-type loci described to date, which makes them fascinating models to investigate the evolutionary mechanisms of haploid sex determination in eukaryotes. %B Genome Biology and Evolution %V 13 %P evab216 %G eng %U https://academic.oup.com/gbe/article/doi/10.1093/gbe/evab216/6380139 %R 10.1093/gbe/evab216 %0 Journal Article %J Microorganisms %D 2021 %T Features of the Opportunistic Behaviour of the Marine Bacterium Marinobacter algicola in the Microalga Ostreococcus tauri Phycosphere %A Pinto, Jordan %A Lami, Raphaël %A Krasovec, Marc %A Grimaud, Régis %A Urios, Laurent %A Lupette, Josselin %A Escande, Marie-Line %A Sanchez, Frédéric %A Intertaglia, Laurent %A Grimsley, Nigel %A Piganeau, Gwenael %A Sanchez, Sophie %K RCC4221 %X Although interactions between microalgae and bacteria are observed in both natural environment and the laboratory, the modalities of coexistence of bacteria inside microalgae phyco-spheres in laboratory cultures are mostly unknown. Here, we focused on well-controlled cultures of the model green picoalga Ostreococcus tauri and the most abundant member of its phycosphere, Marinobacter algicola. The prevalence of M. algicola in O. tauri cultures raises questions about how this bacterium maintains itself under laboratory conditions in the microalga culture. The results showed that M. algicola did not promote O. tauri growth in the absence of vitamin B12 while M. algicola depended on O. tauri to grow in synthetic medium, most likely to obtain organic carbon sources provided by the microalgae. M. algicola grew on a range of lipids, including triacylglycerols that are known to be produced by O. tauri in culture during abiotic stress. Genomic screening revealed the absence of genes of two particular modes of quorum-sensing in Marinobacter genomes which refutes the idea that these bacterial communication systems operate in this genus. To date, the 'opportunistic' behaviour of M. algicola in the laboratory is limited to several phytoplanktonic species including Chlorophyta such as O. tauri. This would indicate a preferential occurrence of M. algicola in association with these specific microalgae under optimum laboratory conditions. %B Microorganisms %V 9 %P 1777 %G eng %R 10.3390/microorganisms9081777 %0 Journal Article %J Limnology and Oceanography %D 2021 %T Growth-dependent changes in elemental stoichiometry and macromolecular allocation in the coccolithophore Emiliania huxleyi under different environmental conditions %A Zhang, Yong %A Li, Zhengke %A Schulz, Kai G. %A Hu, Yingyu %A Irwin, Andrew J. %A Finkel, Zoe V. %K rcc %K RCC1266 %X The growth rate hypothesis (GRH) posits an increase in ribosomal ribonucleic acid (RNA) content, and therefore cellular phosphorus (P), with increasing growth rate. There is evidence that the GRH may not apply to phytoplankton under all conditions. Here, we experimentally controlled four conditions (light, temperature, pH, and CO2) to alter the growth rate of Emiliania huxleyi, a biogeochemically important coccolithophorid, and monitored changes in RNA, protein, and carbohydrate content. We show that an increase in growth rate caused by increasing light, pH, and CO2 resulted in increased RNA per unit of organic carbon (RNA : POC), but that increasing temperature, leading to increase of growth rate, resulted in a decrease in RNA : POC. Protein per unit of organic carbon (protein : POC) increased in our increased temperature, pH, and CO2 treatments that increased growth rate, but there was little change in protein : POC in our light treatment despite it inducing the same increase in growth rate. Carbohydrate per unit of organic carbon (Carbohydrate : POC) increased with growth rate under increased light and CO2 but did not vary significantly in the temperature or pH treatments. These results indicate that physiological acclimation to specific environmental conditions can lead to contrasting patterns in RNA, protein, and carbohydrate composition and therefore contrasting changes in carbon : nitrogen : phosphorus ratios with growth rate in E. huxleyi. %B Limnology and Oceanography %V 66 %P 2999–3009 %G eng %U https://onlinelibrary.wiley.com/doi/abs/10.1002/lno.11854 %R 10.1002/lno.11854 %0 Journal Article %J Protist %D 2021 %T Hemiselmis aquamarina sp . nov . (Cryptomonadales , Cryptophyceae), a cryptomonad with a novel phycobiliprotein type (Cr-PC 564) %A Magalhães, Karoline %A Lopes dos Santos, Adriana %A Vaulot, Daniel %A de Oliveira, Mariana Cabral %K RCC4102 %K RCC5634 %K to add %B Protist %V in press %G eng %U https://doi.org/10.1016/j.protis.2021.125832 %R 10.1016/j.protis.2021.125832 %0 Journal Article %J Geobiology %D 2021 %T The influence of elevated SiO2(aq) on intracellular silica uptake and microbial metabolism %A Tostevin, Rosalie %A Snow, Joseph T. %A Zhang, Qiong %A Tosca, Nicholas J. %A Rickaby, Rosalind E. M. %K Archaean %K culturing %K microbial metabolism %K Proterozoic %K RCC1 %K RCC1216 %K rcc1512 %K RCC1547 %K rcc539 %K silica %X Microbes are known to accumulate intracellular SiO2(aq) up to 100s of mmol/l from modern seawater (SiO2(aq) <100 µmol/l), despite having no known nutrient requirement for Si. Before the evolution of siliceous skeletons, marine silica concentrations were likely an order of magnitude higher than the modern ocean, raising the possibility that intracellular SiO2(aq) accumulation interfered with normal cellular function in non-silicifying algae. Yet, because few culturing studies have isolated the effects of SiO2(aq) at high concentration, the potential impact of elevated marine silica on early microbial evolution is unknown. Here, we test the influence of elevated SiO2(aq) on eukaryotic algae, as well as a prokaryote species. Our results demonstrate that under SiO2(aq) concentrations relevant to ancient seawater, intracellular Si accumulates to concentrations comparable to those found in siliceous algae such as diatoms. In addition, all eukaryotic algae showed a statistically significant response to the high-Si treatment, including reduced average cell sizes and/or a reduction in the maximum growth rate. In contrast, there was no consistent response to the high-Si treatment by the prokaryote species. Our results highlight the possibility that elevated marine SiO2(aq) may have been an environmental stressor during early eukaryotic evolution. %B Geobiology %V n/a %G eng %U http://onlinelibrary.wiley.com/doi/abs/10.1111/gbi.12442 %R 10.1111/gbi.12442 %0 Journal Article %J Geochimica et Cosmochimica Acta %D 2021 %T An isotope label method for empirical detection of carbonic anhydrase in the calcification pathway of the coccolithophore Emiliania huxleyi %A Zhang, Hongrui %A Blanco-Ameijeiras, Sonia %A Hopkinson, Brian M. %A Bernasconi, Stefano M. %A Mejia, Luz Maria %A Liu, Chuanlian %A Stoll, Heather %K Carbonic anhjydrase %K ccm %K coccolithophore %K Isotopic labelling %K rcc %K rcc1258 %X Coccolithophores are a group of phytoplankton widely distributed in the ocean, which secrete extracellular calcite plates termed coccoliths. Coccoliths have been increasingly employed as an archive for geochemical, ecological and paleoclimate studies in recent years. A robust application of coccolith-based geochemical proxies relies on understanding the carbon acquisition strategies and the pathways of carbon supply for calcification. Carbonic anhydrase (CA) plays important roles in the carbon concentrating mechanism s of aquatic algae and potentially also in calcification. However, it is difficult to independently assess the role of CA in carbon supply for photosynthesis versus calcification. To fill this gap, we explored a new method to detect the CA activity inside coccolithophore. To achieve this, coccolithophores were cultured with oxygen and carbon isotope labeled dissolved inorganic carbon (DIC). By exploiting the different behavior of oxygen and carbon isotopes with (sea)water, this double label method can elucidate the significance of CA activity in the calcification pathway. Application of this method to Emiliania huxleyi shows that CA is present in the calcification pathway, and that there is no significant difference in the CA activity between a high and low CO2 treatment. However, under low CO2 treatment E. huxleyi enhanced the bicarbonate pumping rate on both cell and chloroplast membranes. This novel method could be performed on other species of coccolithophores in the future and have a potential to extend our knowledge on coccolith oxygen isotope vital effects. %B Geochimica et Cosmochimica Acta %V 292 %P 78–93 %G eng %U https://www.sciencedirect.com/science/article/pii/S0016703720305597 %R 10.1016/j.gca.2020.09.008 %0 Journal Article %D 2021 %T Les Efflorescences de Lepidodinium chlorophorum au large de la Loire et de la Vilaine : Déterminisme et conséquences sur la qualité des masses d’eau côtières %A Schapira, Mathilde %A Roux, Pauline %A Andre, Coralie %A Mertens, Kenneth %A Bilien, Gwenael %A Terre Terrillon, Aouregan %A Le Gac-Abernot, Chantal %A Siano, Raffaele %A Quéré, Julien %A Bizzozero, Lucie %A Bonneau, Francoise %A Bouget, Jean-Francois %A Cochennec-Laureau, Nathalie %A Collin, Karine %A Fortune, Mireille %A Gabellec, Raoul %A Le Merrer, Yoann %A Manach, Soazig %A Pierre-Duplessix, Olivier %A Retho, Michael %A Schmitt, Anne %A Souchu, Philippe %A Stachowski-Haberkorn, Sabine %K ? No DOI found %K rcc %K RCC1489 %X Ce projet, organisé en trois actions, avait pour objectif de mieux évaluer les risques d’eaux colorées vertes se produisant sur le secteur côtier situé au large de la Loire et de la Vilaine, en termes (i) de fréquence de ces épisodes, (ii) d’abondance et (iii) de localisation des zones à risque. Action 1 : Amélioration du recensement des eaux vertes à L. chlorophorum Action 2 : Optimisation de l’estimation des abondances de L. chlorophorum Action 3 : Identification des zones à risque au large de la Loire et de la Vilaine. %G eng %U https://archimer.ifremer.fr/doc/00724/83598/ %0 Journal Article %J Proceedings of the National Academy of Sciences %D 2021 %T Marine Synechococcus picocyanobacteria: Light utilization across latitudes %A Six, Christophe %A Ratin, Morgane %A Marie, Dominique %A Corre, Erwan %K ?? Invalid DOI %K RCC2035 %K rcc2382 %K RCC2385 %K RCC2421 %K RCC2527 %K RCC2535 %K RCC2553 %K RCC2570 %K RCC515 %K rcc539 %K rcc752 %K rcc791 %K to add %X

The most ubiquitous cyanobacteria, Synechococcus, have colonized different marine thermal niches through the evolutionary specialization of lineages adapted to different ranges of temperature seawater. We used the strains of Synechococcus temperature ecotypes to study how light utilization has evolved in the function of temperature. The tropical Synechococcus (clade II) was unable to grow under 16 °C but, at temperatures >25 °C, induced very high growth rates that relied on a strong synthesis of the components of the photosynthetic machinery, leading to a large increase in photosystem cross-section and electron flux. By contrast, the Synechococcus adapted to subpolar habitats (clade I) grew more slowly but was able to cope with temperatures <10 °C. We show that growth at such temperatures was accompanied by a large increase of the photoprotection capacities using the orange carotenoid protein (OCP). Metagenomic analyzes revealed that Synechococcus natural communities show the highest prevalence of the ocp genes in low-temperature niches, whereas most tropical clade II Synechococcus have lost the gene. Moreover, bioinformatic analyzes suggested that the OCP variants of the two cold-adapted Synechococcus clades I and IV have undergone evolutionary convergence through the adaptation of the molecular flexibility. Our study points to an important role of temperature in the evolution of the OCP. We, furthermore, discuss the implications of the different metabolic cost of these physiological strategies on the competitiveness of Synechococcus in a warming ocean. This study can help improve the current hypotheses and models aimed at predicting the changes in ocean carbon fluxes in response to global warming.

%B Proceedings of the National Academy of Sciences %V 118 %G eng %U http://www.pnas.org/content/118/38/e2111300118 %R 10.1073/pnas.2111300118 %0 Journal Article %J Frontiers in Marine Science %D 2021 %T Microalgal Diet Influences the Nutritive Quality and Reproductive Investment of the Cyclopoid Copepod Paracyclopina nana %A Dayras, Paul %A Bialais, Capucine %A Sadovskaya, Irina %A Lee, Min-Chul %A Lee, Jae-Seong %A Souissi, Sami %K rcc %K RCC1349 %K RCC1537 %K RCC20 %X Copepods represent an interesting alternative or a complement live food to brine shrimps and rotifers commonly used in aquaculture. They constitute the natural prey of many fish species and therefore do not require a potential nutritional enrichment. But an optimization of the microalgal diets used to feed copepods is essential to improve their mass culture. This study examined the effects of seven microalgal diets, namely single-species diets of Rhodomonas salina (R), Tisochrysis lutea (T), and Pavlova lutheri (=Diacronema lutheri) (P), two-species diets (R + T, T + P, and R + P), and a three-species diet (R + T + P), on the fatty acid and monosaccharide composition of the cyclopoid copepod Paracyclopina nana as well as its reproductive investment. Experiments were run during 15 days in 10-L beakers; starting with nauplii collected from a large 300-L batch culture. Copepods fatty acid contents were studied, particularly the relative amounts of docosahexaenoic acid (DHA) and eicosa-pentaenoic acid (EPA). The R + T, R, and T diets induced the highest total fatty acid amount in copepods. R + T and R also generated the lowest DHA/EPA ratios in copepods due to high EPA contents. The highest value of total monosaccharides was found in copepods fed with R + T + P. Diets R + T and R induced the greatest prosome volumes and clutch volumes in ovigerous females. Both prosome volume and clutch volume in P. nana ovigerous females were correlated to the individual EPA amount. The results demonstrated that all diets including R. salina enhanced the productivity of P. nana in mass culture, particularly when combined with T. lutea. R. salina, and T. lutea induced complementary fatty acid and monosaccharide profiles, confirming that R + T represents the best microalgae combination for productive culture of P. nana. Conversely, P. lutheri did not enhance the nutritional profile nor the fecundity of P. nana in the culture. This study is the first to demonstrate that R. salina is a suitable microalga for productive mass culture of P. nana for use as live food in aquaculture. %B Frontiers in Marine Science %V 8 %P 1147 %G eng %U https://www.frontiersin.org/article/10.3389/fmars.2021.697561 %R 10.3389/fmars.2021.697561 %0 Journal Article %J Proceedings of the National Academy of Sciences %D 2021 %T Molecular bases of an alternative dual-enzyme system for light color acclimation of marine \textit{Synechococcus cyanobacteria %A Grébert, Théophile %A Nguyen, Adam A. %A Pokhrel, Suman %A Joseph, Kes Lynn %A Ratin, Morgane %A Dufour, Louison %A Chen, Bo %A Haney, Allissa M. %A Karty, Jonathan A. %A Trinidad, Jonathan C. %A Garczarek, Laurence %A Schluchter, Wendy M. %A Kehoe, David M. %A Partensky, Frédéric %K RCC2374 %K to add %X

Marine Synechococcus cyanobacteria owe their ubiquity in part to the wide pigment diversity of their light-harvesting complexes. In open ocean waters, cells predominantly possess sophisticated antennae with rods composed of phycocyanin and two types of phycoerythrins (PEI and PEII). Some strains are specialized for harvesting either green or blue light, while others can dynamically modify their light absorption spectrum to match the dominant ambient color. This process, called type IV chromatic acclimation (CA4), has been linked to the presence of a small genomic island occurring in two configurations (CA4-A and CA4-B). While the CA4-A process has been partially characterized, the CA4-B process has remained an enigma. Here we characterize the function of two members of the phycobilin lyase E/F clan, MpeW and MpeQ, in Synechococcus sp. strain A15-62 and demonstrate their critical role in CA4-B. While MpeW, encoded in the CA4-B island and up-regulated in green light, attaches the green light-absorbing chromophore phycoerythrobilin to cysteine-83 of the PEII α-subunit in green light, MpeQ binds phycoerythrobilin and isomerizes it into the blue light-absorbing phycourobilin at the same site in blue light, reversing the relationship of MpeZ and MpeY in the CA4-A strain RS9916. Our data thus reveal key molecular differences between the two types of chromatic acclimaters, both highly abundant but occupying distinct complementary ecological niches in the ocean. They also support an evolutionary scenario whereby CA4-B island acquisition allowed former blue light specialists to become chromatic acclimaters, while former green light specialists would have acquired this capacity by gaining a CA4-A island.

%B Proceedings of the National Academy of Sciences %V 118 %P e2019715118 %G eng %U http://www.pnas.org/lookup/doi/10.1073/pnas.2019715118 %R 10.1073/pnas.2019715118 %0 Journal Article %J Nature Communications %D 2021 %T Morphological bases of phytoplankton energy management and physiological responses unveiled by 3D subcellular imaging %A Uwizeye, Clarisse %A Decelle, Johan %A Jouneau, Pierre-Henri %A Flori, Serena %A Gallet, Benoit %A Keck, Jean-baptiste %A Bo, Davide Dal %A Moriscot, Christine %A Seydoux, Claire %A Chevalier, Fabien %A Schieber, Nicole L. %A Templin, Rachel %A Allorent, Guillaume %A Courtois, Florence %A Curien, Gilles %A Schwab, Yannick %A Schoehn, Guy %A Zeeman, Samuel C. %A Falconet, Denis %A Finazzi, Giovanni %K RCC100 %K RCC4014 %K RCC827 %K RCC909 %X Phytoplankton account for a large proportion of global primary production and comprise a number of phylogenetically distinct lineages. Here, Uwizeye et al. use FIB-SEM to study ultrastructural plasticity of 7 distinct taxa and describe how subcellular organisation is linked to energy metabolism. %B Nature Communications %V 12 %P 1–12 %8 feb %G eng %U http://www.nature.com/articles/s41467-021-21314-0 %R 10.1038/s41467-021-21314-0 %0 Journal Article %J Scientific Reports %D 2021 %T A novel characteristic of a phytoplankton as a potential source of straight-chain alkanes %A Harada, Naomi %A Hirose, Yuu %A Chihong, Song %A Kurita, Hirofumi %A Sato, Miyako %A Onodera, Jonaotaro %A Murata, Kazuyoshi %A Itoh, Fumihiro %K RCC3437 %K RCC4217 %K RCC4577 %K RCC4578 %K RCC5635 %K RCC5639 %X Biosynthesis of hydrocarbons is a promising approach for the production of alternative sources of energy because of the emerging need to reduce global consumption of fossil fuels. However, the suitability of biogenic hydrocarbons as fuels is limited because their range of the number of carbon atoms is small, and/or they contain unsaturated carbon bonds. Here, we report that a marine phytoplankton, Dicrateria rotunda, collected from the western Arctic Ocean, can synthesize a series of saturated hydrocarbons (n-alkanes) from C10H22 to C38H78, which are categorized as petrol (C10–C15), diesel oils (C16–C20), and fuel oils (C21–C38). The observation that these n-alkanes were also produced by ten other cultivated strains of Dicrateria collected from the Atlantic and Pacific oceans suggests that this capability is a common characteristic of Dicrateria. We also identified that the total contents of the n-alkanes in the Arctic D. rotunda strain increased under dark and nitrogen-deficient conditions. The unique characteristic of D. rotunda could contribute to the development of a new approach for the biosynthesis of n-alkanes. %B Scientific Reports %V 11 %P 14190 %G eng %U http://www.nature.com/articles/s41598-021-93204-w %R 10.1038/s41598-021-93204-w %0 Journal Article %J Processes %D 2021 %T Production of Omega-3 Oil by Aurantiochytrium mangrovei Using Spent Osmotic Solution from Candied Fruit Industry as Sole Organic Carbon Source %A Russo, Giovanni L. %A Langellotti, Antonio L. %A Blasco, Thierry %A Oliviero, Maria %A Sacchi, Raffaele %A Masi, Paolo %K DHA %K food waste %K Microalgae %K PUFA %K rcc %K RCC893 %K sustainability %X Osmotic dehydration is an important phase in the production of dried products, including most fruits and vegetables, in the food industry. The drying process for candied fruit produces a liquid waste called “spent osmotic solution”, which is characterized by a high content of organic compounds, mostly dissolved sugars. The sugar content of this food by-product could be valorized through the growth of biomass with a high added value. In this study, the spent osmotic solution from the candied fruit industry was used as an organic carbon source for the growth and production of docosahexaenoic acid (DHA) in the cultivation of Aurantiochytrium mangrovei RCC893. The carbon content of the standard media was completely replaced by the sugars present in this food by-product. After that, the growth condition of this strain was optimized through response surface methodologies using a central composite design (CCD), and the optimal combination of the spent osmotic solution and nitrogen was established. Moreover, a scale-up trial was performed using the optimal conditions obtained after CCD to evaluate the scalability of the process. %B Processes %V 9 %P 1834 %8 oct %G eng %U https://www.mdpi.com/2227-9717/9/10/1834 %R 10.3390/pr9101834 %0 Journal Article %J BMC Biology %D 2021 %T Rapid protein evolution, organellar reductions, and invasive intronic elements in the marine aerobic parasite dinoflagellate Amoebophrya spp. %A Farhat, Sarah %A Le, Phuong %A Kayal, Ehsan %A Noel, Benjamin %A Bigeard, Estelle %A Corre, Erwan %A Maumus, Florian %A Florent, Isabelle %A Alberti, Adriana %A Aury, Jean-Marc %A Barbeyron, Tristan %A Cai, Ruibo %A Silva, Corinne Da %A Istace, Benjamin %A Labadie, Karine %A Marie, Dominique %A Mercier, Jonathan %A Rukwavu, Tsinda %A Szymczak, Jeremy %A Tonon, Thierry %A Alves-de-Souza, Catharina %A Rouze, Pierre %A de Peer, Yves Van %A Wincker, Patrick %A Rombauts, Stephane %A Porcel, Betina M %A Guillou, Laure %K Dinoflagellate %K genome %K Introner elements %K Non-canonical introns %K parasite %K RCC4383 %K RCC4398 %B BMC Biology %P 1–21 %G eng %R 10.1186/s12915-020-00927-9 %0 Journal Article %J Current Biology %D 2021 %T Rappemonads are haptophyte phytoplankton %A Kawachi, Masanobu %A Nakayama, Takuro %A Kayama, Motoki %A Nomura, Mami %A Miyashita, Hideaki %A Bojo, Othman %A Rhodes, Lesley %A Sym, Stuart %A Pienaar, Richard N. %A Probert, Ian %A Inouye, Isao %A Kamikawa, Ryoma %K environmental DNA sequences %K morphological evolution %K organellar phylogenomics %K phytoplankton diversity %K RCC3430 %K transmission electron microscopy %X Rapidly accumulating genetic data from environmental sequencing approaches have revealed an extraordinary level of unsuspected diversity within marine phytoplankton,1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 which is responsible for around 50% of global net primary production.12,13 However, the phenotypic identity of many of the organisms distinguished by environmental DNA sequences remains unclear. The rappemonads represent a plastid-bearing protistan lineage that to date has only been identified by environmental plastid 16S rRNA sequences.14, 15, 16, 17 The phenotypic identity of this group, which does not confidently cluster in any known algal clades in 16S rRNA phylogenetic reconstructions,15 has remained unknown since the first report of environmental sequences over two decades ago. We show that rappemonads are closely related to a haptophyte microalga, Pavlomulina ranunculiformis gen. nov. et sp. nov., and belong to a new haptophyte class, the Rappephyceae. Organellar phylogenomic analyses provide strong evidence for the inclusion of this lineage within the Haptophyta as a sister group to the Prymnesiophyceae. Members of this new class have a cosmopolitan distribution in coastal and oceanic regions. The relative read abundance of Rappephyceae in a large environmental barcoding dataset was comparable to, or greater than, those of major haptophyte species, such as the bloom-forming Gephyrocapsa huxleyi and Prymnesium parvum, and this result indicates that they likely have a significant impact as primary producers. Detailed characterization of Pavlomulina allowed for reconstruction of the ancient evolutionary history of the Haptophyta, a group that is one of the most important components of extant marine phytoplankton communities. %B Current Biology %8 mar %G eng %U https://www.sciencedirect.com/science/article/pii/S0960982221003511 %R 10.1016/j.cub.2021.03.012 %0 Journal Article %J Environmental Microbiology %D 2021 %T Seasonal dynamics of natural Ostreococcus viral infection at the single cell level using VirusFISH %A Castillo, Yaiza M. %A Forn, Irene %A Yau, Sheree %A Morán, Xosé Anxelu G. %A Alonso-Sáez, Laura %A Arandia-Gorostidi, Néstor %A Vaqué, Dolors %A Sebastián, Marta %K RCC2590 %K RCC4221 %K RCC809 %X Ostreococcus is a cosmopolitan marine genus of phytoplankton found in mesotrophic and oligotrophic waters, and the smallest free-living eukaryotes known to date, with a cell diameter close to 1 μm. Ostreococcus has been extensively studied as a model system to investigate viral–host dynamics in culture, yet the impact of viruses in naturally occurring populations is largely unknown. Here, we used Virus Fluorescence in situ Hybridization (VirusFISH) to visualize and quantify viral-host dynamics in natural populations of Ostreococcus during a seasonal cycle in the central Cantabrian Sea (Southern Bay of Biscay). Ostreococcus were predominantly found during summer and autumn at surface and 50 m depth, in coastal, mid-shelf and shelf waters, representing up to 21% of the picoeukaryotic communities. Viral infection was only detected in surface waters, and its impact was variable but highest from May to July and November to December, when up to half of the population was infected. Metatranscriptomic data available from the mid-shelf station unveiled that the Ostreococcus population was dominated by the species O. lucimarinus. This work represents a proof of concept that the VirusFISH technique can be used to quantify the impact of viruses on targeted populations of key microbes from complex natural communities. This article is protected by copyright. All rights reserved. %B Environmental Microbiology %V n/a %G eng %U http://sfamjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1462-2920.15504 %R 10.1111/1462-2920.15504 %0 Journal Article %J Chemosphere %D 2021 %T Single toxicity of arsenic and combined trace metal exposure to a microalga of ecological and commercial interest: Diacronema lutheri %A Das, Shagnika %A Gevaert, François %A Ouddane, Baghdad %A Duong, Gwendoline %A Souissi, Sami %K Arsenic %K bioaccumulation %K Bioconcentration factor %K Chlorophyll %K de-epoxidation ratio %K RCC1537 %K Trace metals mixture %X Eco-toxicological assays with species of economic interest such as Diacronema lutheri are essential for industries that produce aquaculture feed, natural food additives and also in drug developing industries. Our study involved the exposure of a single and combined toxicity of arsenic (As V) to D. lutheri for the entire algal growth phase and highlighted that a combined exposure of As V with other essential (Copper, Cu; Nickel, Ni) and non-essential (Cadmium, Cd; Lead, Pb) trace metals reduced significantly the cell number, chlorophyll a content, and also significantly increased the de-epoxidation ratio (DR) as a stress response when compared to the single toxicity of As V. Arsenic, as one of the ubiquitous trace metal and an active industrial effluent is reported to have an increased bio-concentration factor when in mixture with other trace metals in this study. In the combined exposure, the concentration of total As bio-accumulated by D. lutheri was higher than in the single exposure. Hence, polluted areas with the prevalence of multiple contaminants along with the highly toxic trace metals like As can impose a greater risk to the exposed organisms that may get further bio-magnified in the food chain. Our study highlights the consequences and the response of D. lutheri in terms of contamination from single and multiple trace metals in order to obtain a safer biomass production for the growing need of natural derivatives. %B Chemosphere %P 132949 %G eng %U https://www.sciencedirect.com/science/article/pii/S0045653521034214 %R 10.1016/j.chemosphere.2021.132949 %0 Journal Article %J PLOS ONE %D 2021 %T Strain-specific morphological response of the dominant calcifying phytoplankton species Emiliania huxleyi to salinity change %A Gebühr, Christina %A Sheward, Rosie M. %A Herrle, Jens O. %A Bollmann, Jörg %K Calcification %K Carbonates %K Ecophysiology %K Marine ecology %K Marine geology %K Morphometry %K Paleoclimatology %K rcc1210 %K RCC1232 %K rcc1824 %K rcc868 %K RCC904 %K salinity %X The future physiology of marine phytoplankton will be impacted by a range of changes in global ocean conditions, including salinity regimes that vary spatially and on a range of short- to geological timescales. Coccolithophores have global ecological and biogeochemical significance as the most important calcifying marine phytoplankton group. Previous research has shown that the morphology of their exoskeletal calcified plates (coccoliths) responds to changing salinity in the most abundant coccolithophore species, Emiliania huxleyi. However, the extent to which these responses may be strain-specific is not well established. Here we investigated the growth response of six strains of E. huxleyi under low (ca. 25) and high (ca. 45) salinity batch culture conditions and found substantial variability in the magnitude and direction of response to salinity change across strains. Growth rates declined under low and high salinity conditions in four of the six strains but increased under both low and high salinity in strain RCC1232 and were higher under low salinity and lower under high salinity in strain PLYB11. When detailed changes in coccolith and coccosphere size were quantified in two of these strains that were isolated from contrasting salinity regimes (coastal Norwegian low salinity of ca. 30 and Mediterranean high salinity of ca. 37), the Norwegian strain showed an average 26% larger mean coccolith size at high salinities compared to low salinities. In contrast, coccolith size in the Mediterranean strain showed a smaller size trend (11% increase) but severely impeded coccolith formation in the low salinity treatment. Coccosphere size similarly increased with salinity in the Norwegian strain but this trend was not observed in the Mediterranean strain. Coccolith size changes with salinity compiled for other strains also show variability, strongly suggesting that the effect of salinity change on coccolithophore morphology is likely to be strain specific. We propose that physiological adaptation to local conditions, in particular strategies for plasticity under stress, has an important role in determining ecotype responses to salinity. %B PLOS ONE %V 16 %P e0246745 %8 feb %G eng %U https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0246745 %R 10.1371/journal.pone.0246745 %0 Journal Article %J bioRxiv %D 2021 %T Subcellular architecture and metabolic connection in the planktonic photosymbiosis between Collodaria (radiolarians) and their microalgae %A Decelle, Johan %A Veronesi, Giulia %A LeKieffre, Charlotte %A Gallet, Benoit %A Chevalier, Fabien %A Stryhanyuk, Hryhoriy %A Marro, Sophie %A Ravanel, Stéphane %A Tucoulou, Rémi %A Schieber, Nicole %A Finazzi, Giovanni %A Schwab, Yannick %A Musat, Niculina %X Photosymbiosis is widespread and ecologically important in the oceanic plankton but remains poorly studied. Here, we used multimodal subcellular imaging to investigate the photosymbiosis between colonial Collodaria and their microalga dinoflagellate (Brandtodinium) collected in surface seawaters. We showed that this symbiosis is a very dynamic system whereby symbionts interact with different host cells via extracellular vesicles within the “greenhouse-like” colony. 3D electron microscopy revealed that the volume of the photosynthetic apparatus (plastid and pyrenoid) of the microalgae increased in symbiosis compared to free-living while the mitochondria volume was similar. Stable isotope probing coupled with NanoSIMS showed that carbon and nitrogen were assimilated and stored in the symbiotic microalga in starch granules and purine crystals, respectively. Nitrogen was also allocated to the algal nucleus (nucleolus). After 3 hours, low 13C and 15N transfer was detected in the host Golgi. Metal mapping revealed that intracellular iron concentration was similar in free-living and symbiotic microalgae (ca 40 ppm) and two-fold higher in the host, whereas copper concentration increased in symbiotic microalgae (up to 6900 ppm) and was detected in the host cell and extracellular vesicles. Sulfur mapping also pinpointed the importance of this nutrient for the algal metabolism. This study, which revealed subcellular changes of the morphology and nutrient homeostasis in symbiotic microalgae, improves our understanding on the metabolism of this widespread and abundant oceanic symbiosis and paves the way for more studies to investigate the metabolites exchanged. %B bioRxiv %P 2021.03.13.435225 %G eng %U https://www.biorxiv.org/content/10.1101/2021.03.13.435225v1 %R 10.1101/2021.03.13.435225 %0 Journal Article %J Frontiers in Earth Science %D 2021 %T Temperature Induced Physiological Reaction Norms of the Coccolithophore Gephyrocapsa oceanica and Resulting Coccolith Sr/Ca and Mg/Ca Ratios %A Müller, Marius N. %A Blanco-Ameijeiras, Sonia %A Stoll, Heather M. %A Méndez-Vicente, Ana %A Lebrato, Mario %K rcc %K RCC1303 %X Coccolithophores are one of the major contributors to the pelagic production of calcium carbonate and their fossilized remains are a key component of the biogeochemical cycles of calcium (Ca), magnesium (Mg), and other divalent cations present in the intracellular precipitated calcitic structures (coccoliths). The geochemical signature of coccoliths (e.g., Sr/Ca and Mg/Ca ratios) is used as paleoproxy to reconstruct past environmental conditions and to understand the underlying physiological precipitation kinetics. Here, we present the elemental fractionation of Sr and Mg in calcite of the coccolithophore Gephyrocapsa oceanica from controlled laboratory experiments applying an extended temperature gradient (12 to 27°C). The physiological reaction norm of G. oceanica, in terms of growth rate, exhibited optimum behavior while the partition coefficient of Sr (DSr) was linearly correlated with temperature and DMg indicated no specific trend. Our results indicate: (1) a presumably secondary physiological control of DSr, and (2) the importance of calibrating coccolithophore-based proxies using experiments that include the full physiological reaction norms (i.e., a possible non-linear response) to environmental drivers (e.g., temperature, salinity, and pH, etc.). The presented results contribute to an improved understanding of the underlying physiological kinetics involved in regulating coccolith elemental fractionation and give additional implications for designing future laboratory experiments to calibrate and apply coccolithophore based paleoproxies on the fossil sediment record. %B Frontiers in Earth Science %V 9 %P 273 %G eng %U https://www.frontiersin.org/article/10.3389/feart.2021.582521 %R 10.3389/feart.2021.582521 %0 Journal Article %J The ISME Journal %D 2021 %T Viruses infecting a warm water picoeukaryote shed light on spatial co-occurrence dynamics of marine viruses and their hosts %A Bachy, Charles %A Yung, Charmaine C. M. %A Needham, David M. %A Gazitúa, Maria Consuelo %A Roux, Simon %A Limardo, Alexander J. %A Choi, Chang Jae %A Jorgens, Danielle M. %A Sullivan, Matthew B. %A Worden, Alexandra Z. %K RCC715 %K RCC716 %X The marine picoeukaryote Bathycoccus prasinos has been considered a cosmopolitan alga, although recent studies indicate two ecotypes exist, Clade BI (B. prasinos) and Clade BII. Viruses that infect Bathycoccus Clade BI are known (BpVs), but not that infect BII. We isolated three dsDNA prasinoviruses from the Sargasso Sea against Clade BII isolate RCC716. The BII-Vs do not infect BI, and two (BII-V2 and BII-V3) have larger genomes (\textasciitilde210 kb) than BI-Viruses and BII-V1. BII-Vs share \textasciitilde90% of their proteins, and between 65% to 83% of their proteins with sequenced BpVs. Phylogenomic reconstructions and PolB analyses establish close-relatedness of BII-V2 and BII-V3, yet BII-V2 has 10-fold higher infectivity and induces greater mortality on host isolate RCC716. BII-V1 is more distant, has a shorter latent period, and infects both available BII isolates, RCC716 and RCC715, while BII-V2 and BII-V3 do not exhibit productive infection of the latter in our experiments. Global metagenome analyses show Clade BI and BII algal relative abundances correlate positively with their respective viruses. The distributions delineate BI/BpVs as occupying lower temperature mesotrophic and coastal systems, whereas BII/BII-Vs occupy warmer temperature, higher salinity ecosystems. Accordingly, with molecular diagnostic support, we name Clade BII Bathycoccus calidus sp. nov. and propose that molecular diversity within this new species likely connects to the differentiated host-virus dynamics observed in our time course experiments. Overall, the tightly linked biogeography of Bathycoccus host and virus clades observed herein supports species-level host specificity, with strain-level variations in infection parameters. %B The ISME Journal %P 1–19 %8 may %G eng %U https://www.nature.com/articles/s41396-021-00989-9 %R 10.1038/s41396-021-00989-9 %0 Journal Article %J Aquaculture Research %D 2020 %T Assessments of first feeding protocols on the larviculture of California grunion Leuresthes tenuis (Osteichthyes: Atherinopsidae) %A Pan, Yen Ju %A Déposé, Emilien %A Souissi, Anissa %A Hénard, Stéphane %A Schaadt, Mike %A Mastro, Ed %A Souissi, Sami %K California grunion %K Copepod %K larval rearing %K live feed %K quiescent egg %K RCC350 %B Aquaculture Research %V 51 %P 3054–3058 %8 jul %G eng %U https://onlinelibrary.wiley.com/doi/10.1111/are.14637 %R 10.1111/are.14637 %0 Journal Article %J Symbiosis %D 2020 %T Better off alone? New insights in the symbiotic relationship between the flatworm Symsagittifera roscoffensis and the microalgae Tetraselmis convolutae %A Androuin, Thibault %A Six, Christophe %A Bordeyne, François %A de Bettignies, Florian %A Noisette, Fanny %A Davoult, Dominique %K Animal-plant %K Photobiology %K RCC1563 %K symbiosis %K Symsagittifera roscoffensis %K Tetraselmis convolutae %X The acoel flatworm Symsagittifera roscoffensis lives in obligatory symbiosis with the microalgal chlorophyte Tetraselmis convolutae. Although this interaction has been studied for more than a century, little is known on the potential reciprocal benefits of both partners, a subject that is still controversial. In order to provide new insights into this question, we have compared the photophysiology of the free-living microalgae to the symbiotic form in the flatworm, both acclimated at different light irradiances. Photosynthesis – Irradiance curves showed that the free-living T. convolutae had greater photosynthetic performance (i.e., oxygen production rates, ability to harvest light) than their symbiotic form, regardless of the light acclimation. However, they were affected by photoinhibition under high irradiances, which did not happen for the symbiotic form. The resistance of symbiotic microalgae to photoinhibition were corroborated by pigment analyses, which evidenced the induction of photoprotective mechanisms such as xanthophyll cycle as well as lutein and β-carotene accumulation. These processes were induced even under low light acclimation and exacerbated upon high light acclimation, suggesting a global stress situation for the symbiotic microalgae. We hypothesize that the internal conditions in the sub-epidermal zone of the flatworm (e.g., osmotic and pH), as well as the phototaxis toward high light imposed by the worm in its environment, would be major reasons for this chronic stress situation. Overall, our study suggests that the relationship between S. roscoffensis and T. convolutae may be a farming strategy in favor of the flatworm rather than a symbiosis with mutual benefits. %B Symbiosis %8 jun %G eng %U http://link.springer.com/10.1007/s13199-020-00691-y %R 10.1007/s13199-020-00691-y %0 Journal Article %J European Journal of Phycology %D 2020 %T Characterization of a lipid-producing thermotolerant marine photosynthetic pico-alga in the genus Picochlorum (Trebouxiophyceae) %A Mucko, Maja %A Padisák, Judit %A Gligora Udovič, Marija %A Pálmai, Tamás %A Novak, Tihana %A Medić, Nikola %A Gašparović, Blaženka %A Peharec Štefanić, Petra %A Orlić, Sandi %A Ljubešić, Zrinka %K morphology %K photosynthetic picoeukaryotes %K phylogeny %K physiology %K Picochlorum %K RCC1034 %K RCC13 %K RCC14 %K rcc289 %K RCC475 %K RCC6905 %K RCC846 %K RCC9 %K RCC945 %B European Journal of Phycology %V 00 %P 1–16 %8 aug %G eng %U https://doi.org/10.1080/09670262.2020.1757763 https://www.tandfonline.com/doi/full/10.1080/09670262.2020.1757763 %R 10.1080/09670262.2020.1757763 %0 Journal Article %J Biochimica et Biophysica Acta (BBA) - Bioenergetics %D 2020 %T CpeY is a phycoerythrobilin lyase for cysteine 82 of the phycoerythrin I α-subunit in marine Synechococcus %A Carrigee, Lyndsay A. %A Mahmoud, Rania M. %A Sanfilippo, Joseph E. %A Frick, Jacob P. %A Strnat, Johann A. %A Karty, Jonathan A. %A Chen, Bo %A Kehoe, David M. %A Schluchter, Wendy M. %K rcc555 %B Biochimica et Biophysica Acta (BBA) - Bioenergetics %P 148215 %8 apr %G eng %U https://doi.org/10.1016/j.bbamem.2019.183135 https://linkinghub.elsevier.com/retrieve/pii/S0005272820300657 %R 10.1016/j.bbabio.2020.148215 %0 Journal Article %J Scientific Reports %D 2020 %T Cryptic species in the parasitic Amoebophrya species complex revealed by a polyphasic approach %A Cai, Ruibo %A Kayal, Ehsan %A Alves-de-Souza, Catharina %A Bigeard, Estelle %A Corre, Erwan %A Jeanthon, Christian %A Marie, Dominique %A Porcel, Betina M %A Siano, Raffaele %A Szymczak, Jeremy %A Wolf, Matthias %A Guillou, Laure %K RCC1627 %K RCC1720 %K RCC3018 %K RCC3043 %K RCC3044 %K RCC3047 %K RCC3048 %K RCC3049 %K RCC3145 %K RCC3278 %K RCC3596 %K RCC4381 %K RCC4382 %K RCC4383 %K RCC4384 %K RCC4385 %K RCC4386 %K RCC4387 %K RCC4388 %K RCC4389 %K RCC4390 %K RCC4391 %K RCC4392 %K RCC4393 %K RCC4394 %K RCC4395 %K RCC4396 %K RCC4397 %K RCC4398 %K RCC4399 %K RCC4400 %K RCC4401 %K RCC4402 %K RCC4403 %K RCC4404 %K RCC4405 %K RCC4406 %K RCC4407 %K RCC4408 %K RCC4409 %K RCC4410 %K RCC4411 %K RCC4412 %K RCC4413 %K RCC4414 %K RCC4415 %K RCC4416 %K RCC4711 %K RCC4712 %K RCC4713 %K RCC4715 %K RCC4716 %K RCC4722 %K RCC4723 %K RCC4726 %K RCC4728 %K RCC4729 %K RCC4732 %K RCC4733 %K RCC4734 %K RCC5984 %K RCC5985 %K RCC5986 %K RCC5987 %K RCC5988 %K RCC5989 %K RCC5990 %K RCC5991 %K RCC5992 %K RCC5993 %K RCC5994 %K RCC5995 %K RCC5997 %K RCC5998 %K RCC5999 %K RCC6000 %K RCC6001 %K RCC6002 %K RCC6003 %K RCC6004 %K RCC6005 %K RCC6006 %K RCC6007 %K RCC6008 %K RCC6009 %K RCC6010 %K RCC6079 %K RCC6080 %K RCC6081 %K RCC6082 %K RCC6083 %K RCC6084 %K RCC6085 %K RCC6087 %K RCC6088 %K RCC6094 %K RCC6096 %K RCC6100 %K RCC6101 %K RCC6102 %K RCC6103 %K RCC6104 %K RCC6105 %K RCC6106 %K RCC6107 %K RCC6108 %K RCC6109 %K RCC6110 %K RCC6111 %K RCC6112 %K RCC6113 %K RCC6115 %K RCC6116 %K RCC6117 %K RCC6118 %K RCC6119 %K RCC6120 %K RCC6121 %B Scientific Reports %V 10 %P 2531 %8 dec %G eng %U http://dx.doi.org/10.1038/s41598-020-59524-z http://www.nature.com/articles/s41598-020-59524-z %R 10.1038/s41598-020-59524-z %0 Journal Article %J Elementa: Science of the Anthropocene %D 2020 %T Culturable diversity of Arctic phytoplankton during pack ice melting %A Ribeiro, Catherine Gérikas %A dos Santos, Adriana Lopes %A Gourvil, Priscillia %A Le Gall, Florence %A Marie, Dominique %A Tragin, Margot %A Probert, Ian %A Vaulot, Daniel %K RCC5197 %K RCC5198 %K RCC5199 %K RCC5200 %K RCC5201 %K RCC5202 %K RCC5203 %K RCC5204 %K RCC5205 %K RCC5206 %K RCC5207 %K RCC5208 %K RCC5209 %K RCC5210 %K RCC5211 %K RCC5212 %K RCC5213 %K RCC5214 %K RCC5215 %K RCC5216 %K RCC5217 %K RCC5218 %K RCC5219 %K RCC5220 %K RCC5221 %K RCC5222 %K RCC5223 %K RCC5224 %K RCC5225 %K RCC5226 %K RCC5227 %K RCC5228 %K RCC5229 %K RCC5230 %K RCC5231 %K RCC5232 %K RCC5233 %K RCC5234 %K RCC5235 %K RCC5236 %K RCC5237 %K RCC5238 %K RCC5239 %K RCC5240 %K RCC5241 %K RCC5242 %K RCC5243 %K RCC5244 %K RCC5245 %K RCC5246 %K RCC5247 %K RCC5248 %K RCC5249 %K RCC5250 %K RCC5251 %K RCC5252 %K RCC5253 %K RCC5254 %K RCC5255 %K RCC5256 %K RCC5257 %K RCC5258 %K RCC5259 %K RCC5260 %K RCC5261 %K RCC5262 %K RCC5263 %K RCC5264 %K RCC5265 %K RCC5266 %K RCC5267 %K RCC5268 %K RCC5269 %K RCC5270 %K RCC5271 %K RCC5272 %K RCC5273 %K RCC5274 %K RCC5275 %K RCC5276 %K RCC5277 %K RCC5278 %K RCC5279 %K RCC5280 %K RCC5281 %K RCC5282 %K RCC5283 %K RCC5284 %K RCC5285 %K RCC5286 %K RCC5287 %K RCC5288 %K RCC5289 %K RCC5290 %K RCC5291 %K RCC5292 %K RCC5293 %K RCC5294 %K RCC5295 %K RCC5296 %K RCC5297 %K RCC5298 %K RCC5299 %K RCC5300 %K RCC5301 %K RCC5302 %K RCC5303 %K RCC5304 %K RCC5305 %K RCC5306 %K RCC5307 %K RCC5308 %K RCC5309 %K RCC5310 %K RCC5311 %K RCC5312 %K RCC5313 %K RCC5314 %K RCC5315 %K RCC5316 %K RCC5317 %K RCC5318 %K RCC5319 %K RCC5320 %K RCC5321 %K RCC5322 %K RCC5323 %K RCC5324 %K RCC5325 %K RCC5326 %K RCC5327 %K RCC5328 %K RCC5329 %K RCC5330 %K RCC5331 %K RCC5332 %K RCC5333 %K RCC5334 %K RCC5335 %K RCC5336 %K RCC5337 %K RCC5338 %K RCC5339 %K RCC5340 %K RCC5341 %K RCC5342 %K RCC5343 %K RCC5344 %K RCC5345 %K RCC5346 %K RCC5347 %K RCC5348 %K RCC5349 %K RCC5350 %K RCC5351 %K RCC5352 %K RCC5353 %K RCC5354 %K RCC5355 %K RCC5356 %K RCC5357 %K RCC5358 %K RCC5359 %K RCC5360 %K RCC5361 %K RCC5362 %K RCC5363 %K RCC5364 %K RCC5365 %K RCC5366 %K RCC5367 %K RCC5368 %K RCC5369 %K RCC5370 %K RCC5371 %K RCC5372 %K RCC5373 %K RCC5374 %K RCC5375 %K RCC5376 %K RCC5377 %K RCC5378 %K RCC5379 %K RCC5380 %K RCC5381 %K RCC5382 %K RCC5383 %K RCC5384 %K RCC5385 %K RCC5386 %K RCC5387 %K RCC5388 %K RCC5389 %K RCC5390 %K RCC5391 %K RCC5392 %K RCC5393 %K RCC5394 %K RCC5395 %K RCC5396 %K RCC5397 %K RCC5398 %K RCC5399 %K RCC5400 %K RCC5401 %K RCC5402 %K RCC5403 %K RCC5404 %K RCC5405 %K RCC5406 %K RCC5407 %K RCC5408 %K RCC5409 %K RCC5410 %K RCC5411 %K RCC5412 %K RCC5413 %K RCC5414 %K RCC5415 %K RCC5416 %K RCC5417 %K RCC5418 %K RCC5419 %K RCC5420 %K RCC5421 %K RCC5422 %K RCC5423 %K RCC5424 %K RCC5425 %K RCC5426 %K RCC5427 %K RCC5428 %K RCC5429 %K RCC5430 %K RCC5431 %K RCC5432 %K RCC5433 %K RCC5434 %K RCC5435 %K RCC5436 %K RCC5437 %K RCC5438 %K RCC5439 %K RCC5440 %K RCC5441 %K RCC5442 %K RCC5443 %K RCC5444 %K RCC5445 %K RCC5446 %K RCC5447 %K RCC5448 %K RCC5449 %K RCC5450 %K RCC5451 %K RCC5452 %K RCC5453 %K RCC5454 %K RCC5455 %K RCC5456 %K RCC5457 %K RCC5458 %K RCC5459 %K RCC5460 %K RCC5461 %K RCC5462 %K RCC5463 %K RCC5464 %K RCC5465 %K RCC5466 %K RCC5467 %K RCC5468 %K RCC5469 %K RCC5470 %K RCC5471 %K RCC5472 %K RCC5473 %K RCC5474 %K RCC5475 %K RCC5476 %K RCC5477 %K RCC5478 %K RCC5479 %K RCC5480 %K RCC5481 %K RCC5482 %K RCC5483 %K RCC5484 %K RCC5485 %K RCC5486 %K RCC5487 %K RCC5488 %K RCC5489 %K RCC5490 %K RCC5491 %K RCC5492 %K RCC5493 %K RCC5494 %K RCC5495 %K RCC5496 %K RCC5497 %K RCC5498 %K RCC5499 %K RCC5500 %K RCC5501 %K RCC5502 %K RCC5503 %K RCC5504 %K RCC5505 %K RCC5506 %K RCC5507 %K RCC5508 %K RCC5509 %K RCC5510 %K RCC5511 %K RCC5512 %K RCC5513 %K RCC5514 %K RCC5515 %K RCC5516 %K RCC5517 %K RCC5518 %K RCC5519 %K RCC5520 %K RCC5521 %K RCC5522 %K RCC5523 %K RCC5524 %K RCC5525 %K RCC5526 %K RCC5527 %K RCC5528 %K RCC5529 %K RCC5530 %K RCC5531 %K RCC5532 %K RCC5533 %K RCC5534 %K RCC5535 %K RCC5536 %K RCC5537 %K RCC5538 %K RCC5539 %K RCC5540 %K RCC5541 %K RCC5542 %K RCC5543 %K RCC5544 %K RCC5545 %K RCC5546 %K RCC5547 %K RCC5548 %K RCC5549 %K RCC5550 %K RCC5551 %K RCC5552 %K RCC5553 %K RCC5554 %K RCC5555 %K RCC5556 %K RCC5557 %K RCC5558 %K RCC5559 %K RCC5560 %K RCC5561 %K RCC5562 %K RCC5563 %K RCC5564 %K RCC5565 %K RCC5566 %K RCC5567 %K RCC5568 %K RCC5569 %K RCC5570 %K RCC5571 %K RCC5572 %K RCC5573 %K RCC5574 %K RCC5575 %K RCC5576 %K RCC5577 %K RCC5578 %K RCC5579 %K RCC5580 %K RCC5581 %K RCC5582 %K RCC5583 %K RCC5584 %K RCC5585 %K RCC5586 %K RCC5587 %K RCC5588 %K RCC5589 %K RCC5590 %K RCC5591 %K RCC5592 %K RCC5593 %K RCC5594 %K RCC5595 %K RCC5596 %K RCC5597 %K RCC5598 %K RCC5599 %K RCC5600 %K RCC5601 %K RCC5602 %K RCC5603 %K RCC5604 %K RCC5605 %K RCC5606 %K RCC5607 %K RCC5608 %K RCC5609 %K RCC5610 %K RCC5611 %K RCC5612 %X Massive phytoplankton blooms develop at the Arctic ice edge, sometimes extending far under the pack ice. An extensive culturing effort was conducted before and during a phytoplankton bloom in Baffin Bay between April and July 2016. Different isolation strategies were applied, including flow cytometry cell sorting, manual single cell pipetting and serial dilution. Although all three techniques yielded the most common organisms, each technique retrieved specific taxa, highlighting the importance of using several methods to maximize the number and diversity of isolated strains. More than 1,000 cultures were obtained, characterized by 18S rRNA sequencing and optical microscopy and de-replicated to a subset of 276 strains presented in this work. Strains grouped into 57 genotypes defined by 100% 18S rRNA sequence similarity. These genotypes spread across five divisions: Heterokontophyta, Chlorophyta, Cryptophyta, Haptophyta and Dinophyta. Diatoms were the most abundant group (193 strains), mostly represented by the genera Chaetoceros and Attheya. The genera Rhodomonas and Pyramimonas were the most abundant non-diatom nanoplankton strains, while Micromonas polaris dominated the picoplankton. Diversity at the class level was higher during the peak of the bloom. Potentially new species were isolated, in particular within the genera Navicula, Nitzschia, Coscinodiscus, Thalassiosira, Pyramimonas, Mantoniella and Isochrysis. %B Elementa: Science of the Anthropocene %V 8 %P 6 %8 feb %G eng %U https://www.biorxiv.org/content/10.1101/642264v1 https://www.elementascience.org/article/10.1525/elementa.401/ %R 10.1525/elementa.401 %0 Journal Article %J Frontiers in Microbiology %D 2020 %T Dinoflagellate host chloroplasts and mitochondria remain functional during amoebophrya infection %A Kayal, Ehsan %A Alves-de-Souza, Catharina %A Farhat, Sarah %A Velo-Suarez, Lourdes %A Monjol, Joanne %A Szymczak, Jeremy %A Bigeard, Estelle %A Marie, Dominique %A Noel, Benjamin %A Porcel, Betina M %A Corre, Erwan %A Six, Christophe %A Guillou, Laure %K amoebophrya %K chloroplast %K Dinoflagellate %K frontiers in microbiology %K frontiersin %K kleptoplast %K marine plankton %K org %K organelles %K parasitism %K RCC1627 %K RCC4398 %K www %X Dinoflagellates are major components of phytoplankton that play critical roles in many microbial food webs, many of them being hosts of countless intracellular parasites. The phototrophic dinoflagellate Scrippsiella acuminata (Dinophyceae) can be infected by the microeukaryotic parasitoids Amoebophrya spp. (Syndiniales), some of which primarily target and digest the host nucleus. Early digestion of the nucleus at the beginning of the infection is expected to greatly impact the host metabolism, inducing the knockout of the organellar machineries that highly depend upon nuclear gene expression, such as the mitochondrial OXPHOS pathway and the plastid photosynthetic carbon fixation. However, previous studies have reported that chloroplasts remain functional in swimming host cells infected by Amoebophrya . We report here a multi-approach monitoring study of S. acuminata organelles over a complete infection cycle by nucleus-targeting Amoebophrya sp. strain A120. Our results show sustained and efficient photosystem II activity as a hallmark of functional chloroplast throughout the infection period despite the complete digestion of the host nucleus. We also report the importance played by light on parasite production, i.e., the amount of host biomass converted to parasite infective propagules. Using a differential gene expression analysis, we observed an apparent increase of all 3 mitochondrial and 9 out of the 11 plastidial genes involved in the electron transport chains (ETC) of the respiration pathways during the first stages of the infection. The longer resilience of organellar genes compared to those encoded by the nucleus suggests that both mitochondria and chloroplasts remain functional throughout most of the infection. This extended organelle functionality, along with higher parasite production under light conditions, suggests that host bioenergetic organelles likely benefit the parasite Amoebophrya sp. A120 and improve its fitness during the intracellular infective stage. %B Frontiers in Microbiology %V 11 %P 1–11 %8 dec %G eng %U https://www.frontiersin.org/articles/10.3389/fmicb.2020.600823/full %R 10.3389/fmicb.2020.600823 %0 Journal Article %J The ISME Journal %D 2020 %T Diversity and dynamics of relevant nanoplanktonic diatoms in the Western English Channel %A Arsenieff, Laure %A Le Gall, Florence %A Rigaut-jalabert, Fabienne %A Mahé, Frédéric %A Sarno, Diana %A Gouhier, Léna %A Baudoux, Anne-claire %A Simon, Nathalie %K RCC4657 %K RCC4658 %K RCC4659 %K RCC4660 %K RCC4661 %K RCC4662 %K RCC4663 %K RCC4664 %K RCC4665 %K RCC4666 %K RCC5154 %K RCC5839 %K RCC5840 %K RCC5841 %K RCC5842 %K RCC5843 %K RCC5844 %K RCC5845 %K RCC5846 %K RCC5847 %K RCC5848 %K RCC5849 %K RCC5850 %K RCC5851 %K RCC5852 %K RCC5853 %K RCC5854 %K RCC5855 %K RCC5856 %K RCC5857 %K RCC5859 %K RCC5860 %K RCC5861 %K RCC5862 %K RCC5863 %K RCC5864 %K RCC5865 %K RCC5866 %K RCC5867 %K RCC5868 %K RCC5869 %K RCC5870 %K RCC5871 %K RCC5872 %K RCC5873 %K RCC5875 %K RCC5876 %K RCC5877 %K RCC5878 %K RCC5879 %K RCC5880 %K RCC5881 %K RCC5882 %K RCC5883 %K RCC5884 %K RCC5885 %K RCC5886 %K RCC5887 %K RCC5921 %B The ISME Journal %8 apr %G eng %U http://dx.doi.org/10.1038/s41396-020-0659-6 http://www.nature.com/articles/s41396-020-0659-6 %R 10.1038/s41396-020-0659-6 %0 Journal Article %J Microbiology Resource Announcements %D 2020 %T Draft whole-genome sequence of triparma laevis f. inornata (parmales, bolidophyceae), isolated from the oyashio region, western north pacific ocean %A Kuwata, Akira %A Saitoh, Kenji %A Nakamura, Yoji %A Ichinomiya, Mutsuo %A Sato, Naoki %E Stajich, Jason E. %K RCC4655 %X We present the first draft whole-genome sequence for the Parmales (Bolidophyceae, Heterokonta), a picoplanktonic sister group of diatoms, using a Triparma laevis f. inornata strain that was isolated from the Oyashio region in the western North Pacific Ocean. %B Microbiology Resource Announcements %V 9 %P 13–14 %8 aug %G eng %U https://mra.asm.org/content/9/33/e00367-20 %R 10.1128/MRA.00367-20 %0 Journal Article %J Toxics %D 2020 %T Effect of 10 UV filters on the brine shrimp Artemia salina and themarinemicroalga Tetraselmis sp. %A Thorel, Evane %A Clergeaud, Fanny %A Jaugeon, Lucie %A Rodrigues, Alice M.S. %A Lucas, Julie %A Stien, Didier %A Lebaron, Philippe %K Artemia salina %K marine environment %K Marine microalgae %K RCC500 %K Toxicity tests %K UV-filters %X The presence of pharmaceutical and personal care product (PPCP) residues in the aquatic environment is an emerging issue due to their uncontrolled release through gray water, and accumulation in the environment that may affect living organisms, ecosystems and public health. The aim of this study is to assess the toxicity of benzophenone-3 (BP-3), bis-ethylhexyloxyphenol methoxyphenyl triazine (BEMT), butyl methoxydibenzoylmethane (BM), methylene bis-benzotriazolyl tetramethylbutylphenol (MBBT), 2-ethylhexyl salicylate (ES), diethylaminohydroxybenzoyl hexyl benzoate (DHHB), diethylhexyl butamido triazone (DBT), ethylhexyl triazone (ET), homosalate (HS) and octocrylene (OC) on marine organisms from two major trophic levels, including autotrophs (Tetraselmis sp.) and heterotrophs (Artemia salina). In general, results showed that both HS and OC were the most toxic UV filters for our tested species, followed by a significant effect of BM on Artemia salina due to BM-but only at high concentrations (1 mg/L). ES, BP3 and DHHB affected the metabolic activity of the microalgae at 100 ??g/L. BEMT, DBT, ET, MBBT had no effect on the tested organisms, even at high concentrations (2 mg/L). OC toxicity represents a risk for those species, since concentrations used in this study are 15-90 times greater than those reported in occurrence studies for aquatic environments. For the first time in the literature, we report HS toxicity on a microalgae species at concentrations complementing those found in aquatic environments. These preliminary results could represent a risk in the future if concentrations of OC and HS continue to increase. %B Toxics %V 8 %P 29 %8 jun %G eng %U www.mdpi.com/journal/toxics %R 10.3390/TOXICS8020029 %0 Journal Article %J Talanta %D 2020 %T Electrochemical genosensor for the detection of Alexandrium minutum dinoflagellates %A Morais, Stephanie L. %A Barros, Piedade %A Santos, Marlene %A Delerue-Matos, Cristina %A Gomes, Andreia C. %A Fátima Barroso, M. %K RCC3029 %B Talanta %P 121416 %G eng %U https://doi.org/10.1016/j.talanta.2020.121416 https://linkinghub.elsevier.com/retrieve/pii/S0039914020307074 %R 10.1016/j.talanta.2020.121416 %0 Journal Article %J Frontiers in Microbiology %D 2020 %T Evolutionary mechanisms of long-term genome diversification associated with niche partitioning in marine picocyanobacteria %A Doré, Hugo %A Farrant, Gregory K. %A Guyet, Ulysse %A Haguait, Julie %A Humily, Florian %A Ratin, Morgane %A Pitt, Frances D. %A Ostrowski, Martin %A Six, Christophe %A Brillet-Guéguen, Loraine %A Hoebeke, Mark %A Bisch, Antoine %A Le Corguillé, Gildas %A Corre, Erwan %A Labadie, Karine %A Aury, Jean-Marc %A Wincker, Patrick %A Choi, Dong Han %A Noh, Jae Hoon %A Eveillard, Damien %A Scanlan, David J. %A Partensky, Frédéric %A Garczarek, Laurence %K amino-acid substitutions %K comparative genomics %K evolution %K genomic islands %K marine cyanobacteria %K niche adaptation %K Prochlorococcus %K rcc1084 %K RCC1085 %K RCC1086 %K RCC1087 %K RCC156 %K RCC158 %K rcc162 %K RCC2033 %K RCC2035 %K RCC2319 %K RCC2366 %K RCC2368 %K RCC2369 %K RCC2374 %K RCC2376 %K RCC2378 %K RCC2379 %K rcc2380 %K RCC2381 %K rcc2382 %K RCC2383 %K RCC2385 %K RCC2433 %K RCC2436 %K RCC2438 %K RCC2527 %K RCC2528 %K RCC2533 %K RCC2534 %K RCC2535 %K RCC2553 %K RCC2554 %K RCC2555 %K RCC2556 %K RCC2571 %K RCC2673 %K RCC278 %K rcc296 %K RCC307 %K RCC328 %K RCC3377 %K RCC407 %K RCC515 %K rcc539 %K rcc555 %K RCC556 %K rcc752 %K RCC753 %K rcc791 %K Synechococcus %B Frontiers in Microbiology %V 11 %P 1–23 %8 sep %G eng %U https://www.frontiersin.org/article/10.3389/fmicb.2020.567431/full %R 10.3389/fmicb.2020.567431 %0 Journal Article %J Ecology Letters %D 2020 %T Evolutionary temperature compensation of carbon fixation in marine phytoplankton %A Barton, Samuel %A Jenkins, James %A Buckling, Angus %A Schaum, C.-Elisa %A Smirnoff, Nicholas %A Raven, John A. %A Yvon-Durocher, Gabriel %E Ezenwa, Vanessa %K climate change %K evolutionary ecology %K metabolism %K phytoplankton physiology %K RCC1303 %K rcc1512 %K RCC1773 %K RCC4221 %K RCC623 %K RCC626 %K RCC652 %K RCC80 %K RCC834 %K thermal performance curves %X The efficiency of carbon sequestration by the biological pump could decline in the coming decades because respiration tends to increase more with temperature than photosynthesis. Despite these differences in the short-term temperature sensitivities of photosynthesis and respiration, it remains unknown whether the long-term impacts of global warming on metabolic rates of phytoplankton can be modulated by evolutionary adaptation. We found that respiration was consistently more temperature dependent than photosynthesis across 18 diverse marine phytoplankton, resulting in universal declines in the rate of carbon fixation with short-term increases in temperature. Long-term experimental evolution under high temperature reversed the short-term stimulation of metabolic rates, resulting in increased rates of carbon fixation. Our findings suggest that thermal adaptation may therefore have an ameliorating impact on the efficiency of phytoplankton as primary mediators of the biological carbon pump. %B Ecology Letters %P ele.13469 %8 feb %G eng %U https://onlinelibrary.wiley.com/doi/abs/10.1111/ele.13469 %R 10.1111/ele.13469 %0 Journal Article %J Microbiology Resource Announcements %D 2020 %T Genome sequences of synechococcus sp. Strain MIT S9220 and cocultured cyanophage SynMITS9220M01 %A Belisle, B. Shafer %A Avila Paz, Andres A. %A Carpenter, Angelina R. %A Cormier, Tayla C. %A Lewis, Adam J. %A Menin, Linnea S. %A Oliveira, Daniel R %A Song, Bukyung %A Szeto, Amy %A Tchantouridze, Elizabeth I %A Watson, Kayleigh A %A Yohannes, Mary T %A Ahlgren, Nathan A %E Putonti, Catherine %K RCC2571 %X Synechococcus bacteria are unicellular cyanobacteria that contribute significantly to global marine primary production. We report the nearly complete genome sequence of Synechococcus sp. strain MIT S9220, which lacks the nitrate utilization genes present in most marine Synechococcus genomes. Assembly also produced the complete genome sequence of a cyanophage present in the MIT S9220 culture. %B Microbiology Resource Announcements %V 9 %P 28–30 %8 jul %G eng %U https://mra.asm.org/content/9/30/e00481-20 %R 10.1128/MRA.00481-20 %0 Journal Article %J Frontiers in Marine Science %D 2020 %T Growth and elemental stoichiometry of the ecologically-relevant arctic diatom chaetoceros gelidus: A mix of polar and temperate %A Schiffrine, Nicolas %A Tremblay, Jean-éric %A Babin, Marcel %K ammonium %K Arctic diatom %K ele %K Light %K nitrate %K RCC2046 %K urea %B Frontiers in Marine Science %V 6 %8 jan %G eng %U https://www.frontiersin.org/article/10.3389/fmars.2019.00790/full %R 10.3389/fmars.2019.00790 %0 Journal Article %J Metabolomics %D 2020 %T Identification to species level of live single microalgal cells from plankton samples with matrix-free laser/desorption ionization mass spectrometry %A Baumeister, Tim U H %A Vallet, Marine %A Kaftan, Filip %A Guillou, Laure %A Svatoš, Aleš %A Pohnert, Georg %K ionization high- %K Live single-cell mass spectrometry %K matrix-free laser desorption %K Matrix-free laser desorption/ionization high-resol %K Metabolic fingerprinting %K Microalgal identification %K RCC1717 %K RCC2561 %K RCC2562 %K RCC3008 %K RCC4667 %K RCC5791 %K RCC6807 %K RCC6808 %K RCC6809 %K RCC6810 %K RCC6811 %K RCC6812 %K RCC6813 %K RCC6814 %K RCC6815 %K RCC6816 %K RCC6817 %K RCC6818 %K RCC6819 %K RCC6820 %K RCC6821 %K resolution mass spectrometry %K Spectral pattern matching %K Spectrum similarity %B Metabolomics %V 16 %P 28 %8 mar %G eng %U https://doi.org/10.1007/s11306-020-1646-7 http://link.springer.com/10.1007/s11306-020-1646-7 %R 10.1007/s11306-020-1646-7 %0 Journal Article %J bioRxiv %D 2020 %T In-cell quantitative structural imaging of phytoplankton using 3D electron microscopy %A Uwizeye, Clarisse %A Decelle, Johan %A Jouneau, Pierre-Henri %A Gallet, Benoit %A Keck, Jean-baptiste %A Schwab, Yannick %A Schoehn, Guy %A Zeeman, Samuel C %A Falconet, Denis %A Finazzi, Giovanni %A Moriscot, Christine %A Chevalier, Fabien %A Schieber, Nicole L %A Templin, Rachel %A Curien, Gilles %A Schwab, Yannick %A Schoehn, Guy %A Zeeman, Samuel C %A Falconet, Denis %A Finazzi, Giovanni %K RCC100 %K RCC4014 %K RCC827 %K RCC909 %X Phytoplankton is a minor fraction of the global biomass playing a major role in primary production and climate. Despite improved understanding of phytoplankton diversity and genomics, we lack nanoscale subcellular imaging approaches to understand their physiology and cell biology. Here, we present a complete Focused Ion Beam - Scanning Electron Microscopy (FIB-SEM) workflow (from sample preparation to image processing) to generate nanometric 3D phytoplankton models. Tomograms of entire cells, representatives of six ecologically-successful phytoplankton unicellular eukaryotes, were used for quantitative morphometric analysis. Besides lineage-specific cellular architectures, we observed common features related to cellular energy management: i) conserved cell-volume fractions occupied by the different organelles; ii) consistent plastid-mitochondria interactions, iii) constant volumetric ratios in these energy-producing organelles. We revealed detailed subcellular features related to chromatin organization and to biomineralization. Overall, this approach opens new perspectives to study phytoplankton acclimation responses to abiotic and biotic factors at a relevant biological scale.Competing Interest StatementThe authors have declared no competing interest. %B bioRxiv %P 2020.05.19.104166 %8 jan %G eng %U http://biorxiv.org/content/early/2020/05/20/2020.05.19.104166.abstract %R 10.1101/2020.05.19.104166 %0 Journal Article %J Journal of Phycology %D 2020 %T Influence of temperature and CO 2 on Plasma-membrane permeability to CO 2 and HCO 3 - in the marine haptophytes emiliania huxleyi and calcidiscus leptoporus (prymnesiophyceae) %A Blanco-Ameijeiras, Sonia %A Stoll, Heather M. %A Zhang, Hongrui %A Hopkinson, Brian M. %E Raven, J. %K carbon concentrating mechanism %K CO2 %K haptophyte %K membrane %K PERMEABILITY %K RCC1130 %K rcc1258 %X Membrane permeabilities to CO2 and HCO3- constrain the function of CO2 concentrating mechanisms that algae use to supply inorganic carbon for photosynthesis. In diatoms and green algae, plasma membranes are moderately to highly permeable to CO2 but effectively impermeable to HCO3-. Here, CO2 and HCO3- membrane permeabilities were measured using an 18O-exchange technique on two species of haptophyte algae, Emiliania huxleyi and Calcidiscus leptoporus, which showed that the plasma membranes of these species are also highly permeable to CO2 (0.006–0.02 cm ? s-1) but minimally permeable to HCO3-. Increased temperature and CO2 generally increased CO2 membrane permeabilities in both species, possibly due to changes in lipid composition or CO2 channel proteins. Changes in CO2 membrane permeabilities showed no association with the density of calcium carbonate coccoliths surrounding the cell, which could potentially impede passage of compounds. Haptophyte plasma-membrane permeabilities to CO2 were somewhat lower than those of diatoms but generally higher than membrane permeabilities of green algae. One caveat of these measurements is that the model used to interpret 18O-exchange data assumes that carbonic anhydrase, which catalyzes 18O-exchange, is homogeneously distributed in the cell. The implications of this assumption were tested using a two-compartment model with an inhomogeneous distribution of carbonic anhydrase to simulate 18O-exchange data and then inferring plasma-membrane CO2 permeabilities from the simulated data. This analysis showed that the inferred plasma-membrane CO2 permeabilities are minimal estimates but should be quite accurate under most conditions. %B Journal of Phycology %P jpy.13017 %8 jun %G eng %U https://onlinelibrary.wiley.com/doi/abs/10.1111/jpy.13017 %R 10.1111/jpy.13017 %0 Journal Article %J Geochemistry, Geophysics, Geosystems %D 2020 %T Li partitioning into coccoliths of Emiliania huxleyi : evaluating the general role of “vital effects” in explaining element partitioning in biogenic carbonates %A Langer, Gerald %A Sadekov, Aleksey %A Greaves, Mervyn %A Nehrke, Gernot %A Probert, Ian %A Misra, Sambuddha %A Thoms, Silke %K RCC3652 %X Abstract Emiliania huxleyi cells were grown in artificial seawater of different Li and Ca concentrations and coccolith Li/Ca ratios determined. Coccolith Li/Ca ratios were positively correlated to seawater Li/Ca ratios only if the seawater Li concentration was changed, not if the seawater Ca concentration was changed. This Li partitioning pattern of E. huxleyi was previously also observed in the benthic foraminifer Amphistegina lessonii and inorganically precipitated calcite. We argue that Li partitioning in both E. huxleyi and A. lessonii is dominated by a coupled transmembrane transport of Li and Ca from seawater to the site of calcification. We present a refined version of a recently proposed transmembrane transport model for Li and Ca. The model assumes that Li and Ca enter the cell via Ca channels, the Li flux being dependent on the Ca flux. While the original model features a linear function to describe the experimental data, our refined version uses a power function, changing the stoichiometry of Li and Ca. The version presented here accurately predicts the observed dependence of DLi on seawater Li/Ca ratios. Our data demonstrate that minor element partitioning in calcifying organisms is partly mediated by biological processes even if the partitioning behaviour of the calcifying organism is indistinguishable from that of inorganically precipitated calcium carbonate. %B Geochemistry, Geophysics, Geosystems %P 0–2 %8 jun %G eng %U https://onlinelibrary.wiley.com/doi/abs/10.1029/2020GC009129 %R 10.1029/2020GC009129 %0 Journal Article %J Metabolites %D 2020 %T Metabolomics benefits from orbitrap GC–MS—Comparison of low- and high-resolution GC–MS %A Stettin, Daniel %A Poulin, Remington X. %A Pohnert, Georg %K Comparative metabolomics %K Diatom %K High-resolution mass spectrometry (HRMS) %K Instrument comparison %K Mass Spectrometry (Orbitrap GC-MS) %K Metabolite identification %K Orbitrap Gas Chromatography %K Osmotic stress %K RCC75 %X The development of improved mass spectrometers and supporting computational tools is expected to enable the rapid annotation of whole metabolomes. Essential for the progress is the identification of strengths and weaknesses of novel instrumentation in direct comparison to previous instruments. Orbitrap liquid chromatography (LC)–mass spectrometry (MS) technology is now widely in use, while Orbitrap gas chromatography (GC)–MS introduced in 2015 has remained fairly unexplored in its potential for metabolomics research. This study aims to evaluate the additional knowledge gained in a metabolomics experiment when using the high-resolution Orbitrap GC–MS in comparison to a commonly used unit-mass resolution single-quadrupole GC–MS. Samples from an osmotic stress treatment of a non-model organism, the microalga Skeletonema costatum, were investigated using comparative metabolomics with low- and high-resolution methods. Resulting datasets were compared on a statistical level and on the level of individual compound annotation. Both MS approaches resulted in successful classification of stressed vs. non-stressed microalgae but did so using different sets of significantly dysregulated metabolites. High-resolution data only slightly improved conventional library matching but enabled the correct annotation of an unknown. While computational support that utilizes high-resolution GC–MS data is still underdeveloped, clear benefits in terms of sensitivity, metabolic coverage, and support in structure elucidation of the Orbitrap GC–MS technology for metabolomics studies are shown here. %B Metabolites %V 10 %P 143 %8 apr %G eng %U https://www.mdpi.com/2218-1989/10/4/143 %R 10.3390/metabo10040143 %0 Journal Article %J Algal Research %D 2020 %T Parallelisable non-invasive biomass, fitness and growth measurement of macroalgae and other protists with nephelometry %A Calmes, Benoît %A Strittmatter, Martina %A Jacquemin, Bertrand %A Perrineau, Marie Mathilde %A Rousseau, Céline %A Badis, Yacine %A Cock, J. Mark %A Destombe, Christophe %A Valero, Myriam %A Gachon, Claire M.M. %K Algal cultivation %K Biomass %K Biotechnology %K Nephelometry %K Phenotyping %K RCC149 %K RCC3088 %K RCC3510 %K rcc3553 %X With the exponential development of algal aquaculture and blue biotechnology, there is a strong demand for simple, inexpensive, high-throughput, quantitative phenotyping assays to measure the biomass, growth and fertility of algae and other marine protists. Here, we validate nephelometry, a method that relies on measuring the scattering of light by particles in suspension, as a non-invasive tool to measure in real-time the biomass of aquatic micro-organisms, such as microalgae, filamentous algae, as well as non-photosynthetic protists. Nephelometry is equally applicable to optic density and chlorophyll fluorescence measurements for the quantification of some microalgae, but outperforms other spectroscopy methods to quantify the biomass of biofilm-forming and filamentous algae, highly pigmented species and non-photosynthetic eukaryotes. Thanks to its insensitivity to the sample's pigmentation, nephelometry is also the method of choice when chlorophyll content varies between samples or time points, for example due to abiotic stress or pathogen infection. As examples, we illustrate how nephelometry can be combined with fluorometry or image analysis to monitor the quantity and time-course of spore release in fertile kelps or the progression of symptoms in diseased algal cultures. %B Algal Research %V 46 %P 101762 %G eng %U https://doi.org/10.1016/j.algal.2019.101762 %R 10.1016/j.algal.2019.101762 %0 Journal Article %J MicrobiologyOpen %D 2020 %T Phytoplankton-derived zwitterionic gonyol and dimethylsulfonioacetate interfere with microbial dimethylsulfoniopropionate sulfur cycling %A Gebser, Björn %A Thume, Kathleen %A Steinke, Michael %A Pohnert, Georg %K rcc1217 %K rcc1731 %K RCC75 %K RCC76 %K RCC841 %K school of life sciences %K university of essex %B MicrobiologyOpen %P e1014 %8 feb %G eng %U http://doi.wiley.com/10.1002/mbo3.1014 %R 10.1002/mbo3.1014 %0 Journal Article %J Biomolecules %D 2020 %T The polar lipidome of cultured emiliania huxleyi: A source of bioactive lipids with relevance for biotechnological applications %A Aveiro, Susana S. %A Melo, Tânia %A Figueiredo, Ana %A Domingues, Pedro %A Pereira, Hugo %A Maia, Inês B. %A Silva, Joana %A Domingues, M. Rosário %A Nunes, Cláudia %A Moreira, Ana S. P. %K Emiliania huxleyi %K haptophyta %K Lipidomics %K Mass spectrometry %K Microalgae %K RCC1250 %X Polar lipids from microalgae have aroused greater interest as a natural source of omega-3 (n-3) polyunsaturated fatty acids (PUFA), an alternative to fish, but also as bioactive compounds with multiple applications. The present study aims to characterize the polar lipid profile of cultured microalga Emiliania huxleyi using hydrophilic interaction liquid chromatography coupled with high-resolution mass spectrometry (HILIC–MS) and fatty acids (FA) analysis by gas chromatography (GC–MS). The lipidome of E. huxleyi revealed the presence of distinct n-3 PUFA (40% of total FA), namely docosahexaenoic acid (22:6n-3) and stearidonic acid (18:4n-3), which give this microalga an increased commercial value as a source of n-3 PUFA present in the form of polar lipids. A total of 134 species of polar lipids were identified and some of these species, particularly glycolipids, have already been reported for their bioactive properties. Among betaine lipids, the diacylglyceryl carboxyhydroxymethylcholine (DGCC) class is the least reported in microalgae. For the first time, monomethylphosphatidylethanolamine (MMPE) has been found in the lipidome of E. huxleyi. Overall, this study highlights the potential of E. huxleyi as a sustainable source of high-value polar lipids that can be exploited for different applications, namely human and animal nutrition, cosmetics, and pharmaceuticals. %B Biomolecules %V 10 %P 1434 %G eng %U https://www.mdpi.com/2218-273X/10/10/1434 %R 10.3390/biom10101434 %0 Journal Article %J Algal Research %D 2020 %T Production of carbohydrates, lipids and polyunsaturated fatty acids (PUFA) by the polar marine microalga Chlamydomonas malina RCC2488 %A Morales-Sánchez, Daniela %A Schulze, Peter S.C. %A Kiron, Viswanath %A Wijffels, René H. %K RCC2488 %B Algal Research %V 50 %P 102016 %8 sep %G eng %U https://linkinghub.elsevier.com/retrieve/pii/S2211926420303477 %R 10.1016/j.algal.2020.102016 %0 Journal Article %J Frontiers in Microbiology %D 2020 %T Synergic effects of temperature and irradiance on the physiology of the marine synechococcus strain WH7803 %A Guyet, Ulysse %A Nguyen, Ngoc A. %A Doré, Hugo %A Haguait, Julie %A Pittera, Justine %A Conan, Maël %A Ratin, Morgane %A Corre, Erwan %A Le Corguillé, Gildas %A Brillet-Guéguen, Loraine %A Hoebeke, Mark %A Six, Christophe %A Steglich, Claudia %A Siegel, Anne %A Eveillard, Damien %A Partensky, Frédéric %A Garczarek, Laurence %K light stress %K marine cyanobacteria %K rcc752 %K Synechococcus %K temperature stress %K transcriptomics %K UV radiations %X Understanding how microorganisms adjust their metabolism to maintain their ability to cope with short-term environmental variations constitutes one of the major current challenges in microbial ecology. Here, the best physiologically characterized marine Synechococcus strain, WH7803, was exposed to modulated light/dark cycles or acclimated to continuous high-light (HL) or low-light (LL), then shifted to various stress conditions, including low (LT) or high temperature (HT), HL and ultraviolet (UV) radiations. Physiological responses were analyzed by measuring time courses of photosystem (PS) II quantum yield, PSII repair rate, pigment ratios and global changes in gene expression. Previously published membrane lipid composition were also used for correlation analyses. These data revealed that cells previously acclimated to HL are better prepared than LL-acclimated cells to sustain an additional light or UV stress, but not a LT stress. Indeed, LT seems to induce a synergic effect with the HL treatment, as previously observed with oxidative stress. While all tested shift conditions induced the downregulation of many photosynthetic genes, notably those encoding PSI, cytochrome b6/f and phycobilisomes, UV stress proved to be more deleterious for PSII than the other treatments, and full recovery of damaged PSII from UV stress seemed to involve the neo-synthesis of a fairly large number of PSII subunits and not just the reassembly of pre-existing subunits after D1 replacement. In contrast, genes involved in glycogen degradation and carotenoid biosynthesis pathways were more particularly upregulated in response to LT. Altogether, these experiments allowed us to identify responses common to all stresses and those more specific to a given stress, thus highlighting genes potentially involved in niche acclimation of a key member of marine ecosystems. Our data also revealed important specific features of the stress responses compared to model freshwater cyanobacteria. %B Frontiers in Microbiology %V 11 %P 1707 %8 jul %G eng %U www.frontiersin.org %R 10.3389/fmicb.2020.01707 %0 Journal Article %J Phycologia %D 2020 %T Taxonomic reassignment of \textit{Pseudohaptolina birgeri comb. nov . (Haptophyta) %A Gérikas Ribeiro, Catherine %A Lopes dos Santos, Adriana %A Probert, Ian %A Vaulot, Daniel %A Edvardsen, Bente %K RCC5268 %K RCC5270 %B Phycologia %V in press %P 1–10 %8 oct %G eng %U https://www.biorxiv.org/content/10.1101/2020.05.06.081489v1 https://www.tandfonline.com/doi/full/10.1080/00318884.2020.1830255 %R 10.1080/00318884.2020.1830255 %0 Journal Article %J bioRxiv %D 2020 %T A thermal trade-off between viral production and degradation drives phytoplankton-virus population dynamics %A Demory, David %A Weitz, Joshua S %A Baudoux, Anne-claire %A Touzeau, Suzanne %A Simon, Natalie %A Rabouille, Sophie %A Sciandra, Antoine %A Bernard, Olivier %K RCC4229 %K RCC4265 %K RCC451 %K RCC4523 %K RCC829 %K RCC834 %X Marine viruses interact with their microbial hosts in dynamic environments shaped by variations in abiotic factors, including temperature. However, the impacts of temperature on viral infection of phytoplankton are not well understood. Here we coupled mathematical modeling with experimental datasets to explore the effect of temperature on three Micromonas-prasinovirus pairs. Our model shows the negative consequences of high temperatures on infection and suggests a temperature-dependent threshold between viral production and degradation. Modeling long-term dynamics in environments with different average temperatures revealed the potential for long-term host-virus coexistence, epidemic free, or habitat loss states. Hence, we generalized our model to global sea surface temperature of present and future seas and show that climate change may influence virus-host dynamics differently depending on the virus-host pair. Our study suggests that temperature-dependent changes in the infectivity of virus particles may lead to shifts in virus-host habitats in warmer oceans, analogous to projected changes in the habitats of macro-and microorganisms . %B bioRxiv %P 2020.08.18.256156 %8 aug %G eng %U https://doi.org/10.1101/2020.08.18.256156 %R 10.1101/2020.08.18.256156 %0 Journal Article %J Science Advances %D 2020 %T Virus-host coexistence in phytoplankton through the genomic lens %A Yau, Sheree %A Krasovec, Marc %A Benites, L. Felipe %A Rombauts, Stephane %A Groussin, Mathieu %A Vancaester, Emmelien %A Aury, Jean-Marc %A Derelle, Evelyne %A Desdevises, Yves %A Escande, Marie-Line %A Grimsley, Nigel %A Guy, Julie %A Moreau, Hervé %A Sanchez-Brosseau, Sophie %A Van de Peer, Yves %A Vandepoele, Klaas %A Gourbière, Sébastien %A Piganeau, Gwenael %K RCC2590 %K RCC2596 %X Virus-microbe interactions in the ocean are commonly described by “boom and bust” dynamics, whereby a numerically dominant microorganism is lysed and replaced by a virus-resistant one. Here, we isolated a microalga strain and its infective dsDNA virus whose dynamics are characterized instead by parallel growth of both the microalga and the virus. Experimental evolution of clonal lines revealed that this viral production originates from the lysis of a minority of virus-susceptible cells, which are regenerated from resistant cells. Whole-genome sequencing demonstrated that this resistant-susceptible switch involved a large deletion on one chromosome. Mathematical modeling explained how the switch maintains stable microalga-virus population dynamics consistent with their observed growth pattern. Comparative genomics confirmed an ancient origin of this “accordion” chromosome despite a lack of sequence conservation. Together, our results show how dynamic genomic rearrangements may account for a previously overlooked coexistence mechanism in microalgae-virus interactions. %B Science Advances %V 6 %P eaay2587 %8 apr %G eng %U https://advances.sciencemag.org/lookup/doi/10.1126/sciadv.aay2587 %R 10.1126/sciadv.aay2587 %0 Journal Article %J Frontiers in Microbiology %D 2020 %T Visualization of viral infection dynamics in a unicellular eukaryote and quantification of viral production using virus fluorescence in situ hybridization %A Castillo, Yaiza M. %A Sebastián, Marta %A Forn, Irene %A Grimsley, Nigel %A Yau, Sheree %A Moraru, Cristina %A Vaqué, Dolors %K culture system %K marine picoeukaryote %K Ostreococcus tauri %K Ostreococcus tauri virus 5 %K RCC4221 %K virus fluorescence in situ hybridization %K virus-host interactions %X One of the major challenges in viral ecology is to assess the impact of viruses in controlling the abundance of specific hosts in the environment. To this end, techniques that enable the detection and quantification of virus-host interactions at the single-cell level are essential. With this goal in mind, we implemented virus fluorescence in situ hybridization (VirusFISH) using as a model the marine picoeukaryote Ostreococcus tauri and its virus Ostreococcus tauri virus 5 (OtV5). VirusFISH allowed the visualization and quantification of the proportion of infected cells during an infection cycle in experimental conditions. We were also able to quantify the abundance of free viruses released during cell lysis, discriminating OtV5 from other mid-level fluorescence phages in our non-axenic infected culture that were not easily distinguishable with flow cytometry. Our results showed that although the major lysis of the culture occurred between 24 and 48 h after OtV5 inoculation, some new viruses were already produced between 8 and 24 h. With this work, we demonstrate that VirusFISH is a promising technique to study specific virus-host interactions in non-axenic cultures and establish a framework for its application in complex natural communities. %B Frontiers in Microbiology %V 11 %P 1559 %8 jul %G eng %U https://www.frontiersin.org/article/10.3389/fmicb.2020.01559/full %R 10.3389/fmicb.2020.01559 %0 Journal Article %J Current Biology %D 2019 %T Algal remodeling in a ubiquitous planktonic photosymbiosis %A Decelle, Johan %A Stryhanyuk, Hryhoriy %A Gallet, Benoit %A Veronesi, Giulia %A Schmidt, Matthias %A Balzano, Sergio %A Marro, Sophie %A Uwizeye, Clarisse %A Jouneau, Pierre-Henri %A Lupette, Josselin %A Jouhet, Juliette %A Maréchal, Éric %A Schwab, Yannick %A Schieber, Nicole L. %A Tucoulou, Rémi %A Richnow, Hans %A Finazzi, Giovanni %A Musat, Niculina %K RCC1719 %X Photosymbiosis between single-celled hosts and microalgae is common in oceanic plankton, especially in oligotrophic surface waters. However, the functioning of this ecologically important cell-cell interaction and the subcellular mechanisms allowing the host to accommodate and benefit from its microalgae remain enigmatic. Here, using a combination of quantitative single-cell structural and chemical imaging techniques (FIB-SEM, nanoSIMS, Synchrotron X-ray fluorescence), we show that the structural organization, physiology, and trophic status of the algal symbionts (the haptophyte Phaeocystis) significantly change within their acantharian hosts compared to their free-living phase in culture. In symbiosis, algal cell division is blocked, photosynthesis is enhanced, and cell volume is increased by up to 10-fold with a higher number of plastids (from 2 to up to 30) and thylakoid membranes. The multiplication of plastids can lead to a 38-fold increase of the total plastid volume in a cell. Subcellular mapping of nutrients (nitrogen and phosphorous) and their stoichiometric ratios shows that symbiotic algae are impoverished in phosphorous and suggests a higher investment in energy-acquisition machinery rather than in growth. Nanoscale imaging also showed that the host supplies a substantial amount of trace metals (e.g., iron and cobalt), which are stored in algal vacuoles at high concentrations (up to 660 ppm). Sulfur mapping reveals a high concentration in algal vacuoles that may be a source of antioxidant molecules. Overall, this study unveils an unprecedented morphological and metabolic transformation of microalgae following their integration into a host, and it suggests that this widespread symbiosis is a farming strategy wherein the host engulfs and exploits microalgae. %B Current Biology %V 29 %P 968–978.e4 %8 mar %G eng %U https://www.sciencedirect.com/science/article/abs/pii/S0960982219301320#undfig1 %R 10.1016/J.CUB.2019.01.073 %0 Journal Article %J Environmental Microbiology %D 2019 %T Closely related viruses of the marine picoeukaryotic alga Ostreococcus lucimarinus exhibit different ecological strategies %A Zimmerman, Amy E. %A Bachy, Charles %A Ma, Xiufeng %A Roux, Simon %A Jang, Ho Bin %A Sullivan, Matthew B. %A Waldbauer, Jacob R. %A Worden, Alexandra Z. %K rcc3401 %K RCC393 %K RCC829 %X SUMMARY In marine ecosystems viruses are major disrupters of the direct flow of carbon and nutrients to higher trophic levels. While the genetic diversity of several eukaryotic phytoplankton virus groups has been characterized, their infection dynamics are less understood, such that the physiological and ecological implications of their diversity remain unclear. We compared genomes and infection phenotypes of the two most closely related cultured phycodnaviruses infecting the widespread picoprasinophyte Ostreococcus lucimarinus under standard- (1.3 divisions d-1) and limited-light (0.41 divisions d-1) nutrient replete conditions. OlV7 infection caused early arrest of the host cell cycle, coinciding with a significantly higher proportion of infected cells than OlV1-amended treatments, regardless of host growth rate. OlV7 treatments showed a near-50-fold increase of progeny virions at the higher host growth rate, contrasting with OlV1's 16-fold increase. However, production of OlV7 virions was more sensitive than OlV1 production to reduced host growth rate, suggesting fitness trade-offs between infection efficiency and resilience to host physiology. Moreover, while organic matter released from OlV1- and OlV7-infected hosts had broadly similar chemical composition, some distinct molecular signatures were observed. Collectively, these results suggest that current views on viral relatedness through marker and core gene analyses underplay operational divergence and consequences for host ecology. This article is protected by copyright. All rights reserved. %B Environmental Microbiology %V 00 %G eng %R 10.1111/1462-2920.14608 %0 Journal Article %J Polar Biology %D 2019 %T Decoupling light harvesting, electron transport and carbon fixation during prolonged darkness supports rapid recovery upon re-illumination in the Arctic diatom Chaetoceros neogracilis %A Lacour, Thomas %A Morin, Philippe-Israël %A Sciandra, Théo %A Donaher, Natalie %A Campbell, Douglas A. %A Ferland, Joannie %A Babin, Marcel %K Arctic microalgae %K Darkness %K Diatom %K GROWTH RATE %K Photosynthesis %K Polar night %K RCC2278 %K temperature %B Polar Biology %8 may %G eng %U https://doi.org/10.1007/s00300-019-02507-2 http://link.springer.com/10.1007/s00300-019-02507-2 %R 10.1007/s00300-019-02507-2 %0 Journal Article %J Journal of Phycology %D 2019 %T Effects of elevated co 2 on growth, calcification and spectral dependence of photoinhibition in the coccolithophore Emiliania huxleyi (Prymnesiophyceae) %A Lorenzo, M. Rosario %A Neale, Patrick J. %A Sobrino, Cristina %A León, Pablo %A Vázquez, Víctor %A Bresnan, Eileen %A Segovia, María %K rcc1226 %B Journal of Phycology %P jpy.12885 %8 may %G eng %U https://onlinelibrary.wiley.com/doi/abs/10.1111/jpy.12885 %R 10.1111/jpy.12885 %0 Journal Article %J Genome Biology and Evolution %D 2019 %T First estimation of the spontaneous mutation rate in Diatoms %A Krasovec, Marc %A Sanchez-Brosseau, Sophie %A Piganeau, Gwenael %E Baer, Charles %K diatoms %K Mutation accumulation %K mutation rate in phaeodactylum %K mutation spectrum %K phaeodactylum %K RCC2967 %K running title %K spontaneous mutation rate %K tricornutum %B Genome Biology and Evolution %V 1 %P 1–23 %G eng %U https://academic.oup.com/gbe/advance-article/doi/10.1093/gbe/evz130/5520952 %R 10.1093/gbe/evz130 %0 Journal Article %J Frontiers in Microbiology %D 2019 %T First viruses infecting the marine diatom guinardia delicatula %A Arsenieff, Laure %A Simon, Nathalie %A Rigaut-jalabert, Fabienne %A Le Gall, Florence %A Chaffron, Samuel %A Corre, Erwan %A Com, Emmanuelle %A Bigeard, Estelle %A Baudoux, Anne-claire %K diatoms %K genomics %K host-virus dynamics %K RCC1000 %K RCC2023 %K RCC3046 %K RCC3083 %K RCC3093 %K RCC3101 %K RCC4657 %K RCC4659 %K RCC4660 %K RCC4667 %K RCC4834 %K RCC5154 %K RCC5777 %K RCC5778 %K RCC5779 %K RCC5780 %K RCC5781 %K RCC5782 %K RCC5783 %K RCC5784 %K RCC5785 %K RCC5787 %K RCC5788 %K RCC5789 %K RCC5790 %K RCC5792 %K RCC5793 %K RCC5794 %K RCC80 %K single-stranded RNA viruses %K Western English Channel %B Frontiers in Microbiology %V 9 %8 jan %G eng %U https://www.frontiersin.org/article/10.3389/fmicb.2018.03235/full %R 10.3389/fmicb.2018.03235 %0 Journal Article %J Organic Geochemistry %D 2019 %T Hydrogen isotope fractionation response to salinity and alkalinity in a calcifying strain of Emiliania huxleyi %A Weiss, Gabriella M. %A Roepert, Anne %A Middelburg, Jack J. %A Schouten, Stefan %A Sinninghe Damsté, Jaap S. %A van der Meer, Marcel T.J. %K RCC2050 %B Organic Geochemistry %8 jun %G eng %U https://linkinghub.elsevier.com/retrieve/pii/S0146638019301020 %R 10.1016/j.orggeochem.2019.06.001 %0 Journal Article %J Proceedings of the National Academy of Sciences %D 2019 %T Interplay between differentially expressed enzymes contributes to light color acclimation in marine Synechococcus %A Sanfilippo, Joseph E. %A Nguyen, Adam A. %A Garczarek, Laurence %A Karty, Jonathan A. %A Pokhrel, Suman %A Strnat, Johann A. %A Partensky, Frédéric %A Schluchter, Wendy M. %A Kehoe, David M. %K RCC1086 %K RCC2035 %K rcc2380 %K rcc2382 %K RCC2385 %K RCC2433 %K RCC2437 %K RCC2528 %K RCC2533 %K RCC2534 %K RCC2535 %K RCC2571 %K RCC2673 %K RCC28 %K RCC307 %K RCC328 %K RCC515 %K rcc555 %K rcc791 %X Marine Synechococcus , a globally important group of cyanobacteria, thrives in various light niches in part due to its varied photosynthetic light-harvesting pigments. Many Synechococcus strains use a process known as chromatic acclimation to optimize the ratio of two chromophores, green-light–absorbing phycoerythrobilin (PEB) and blue-light–absorbing phycourobilin (PUB), within their light-harvesting complexes. A full mechanistic understanding of how Synechococcus cells tune their PEB to PUB ratio during chromatic acclimation has not yet been obtained. Here, we show that interplay between two enzymes named MpeY and MpeZ controls differential PEB and PUB covalent attachment to the same cysteine residue. MpeY attaches PEB to the light-harvesting protein MpeA in green light, while MpeZ attaches PUB to MpeA in blue light. We demonstrate that the ratio of mpeY to mpeZ mRNA determines if PEB or PUB is attached. Additionally, strains encoding only MpeY or MpeZ do not acclimate. Examination of strains of Synechococcus isolated from across the globe indicates that the interplay between MpeY and MpeZ uncovered here is a critical feature of chromatic acclimation for marine Synechococcus worldwide. %B Proceedings of the National Academy of Sciences %V 116 %P 6457–6462 %8 mar %G eng %U http://www.pnas.org/lookup/doi/10.1073/pnas.1810491116 %R 10.1073/pnas.1810491116 %0 Journal Article %J bioRxiv %D 2019 %T MetaEuk – sensitive, high-throughput gene discovery and annotation for large-scale eukaryotic metagenomics %A Levy Karin, Eli %A Mirdita, Milot %A Soeding, Johannes %X Background: Metagenomics is revolutionizing the study of microorganisms and their involvement in biological, biomedical, and geochemical processes, allowing us to investigate by direct sequencing a tremendous diversity of organisms without the need for prior cultivation. Unicellular eukaryotes play essential roles in most microbial communities as chief predators, decomposers, phototrophs, bacterial hosts, symbionts and parasites to plants and animals. Investigating their roles is therefore of great interest to ecology, biotechnology, human health, and evolution. However, the generally lower sequencing coverage, their more complex gene and genome architectures, and a lack of eukaryote-specific experimental and computational procedures have kept them on the sidelines of metagenomics. Results: MetaEuk is a toolkit for high-throughput, reference-based discovery and annotation of protein-coding genes in eukaryotic metagenomic contigs. It performs fast searches with 6-frame-translated fragments covering all possible exons and optimally combines matches into multi-exon proteins. We used a benchmark of seven diverse, annotated genomes to show that MetaEuk is highly sensitive even under conditions of low sequence similarity to the reference database. To demonstrate MetaEuk&\#039;s power to discover novel eukaryotic proteins in large-scale metagenomic data, we assembled contigs from 912 samples of the Tara Oceans project. MetaEuk predicted >12,000,000 protein-coding genes in eight days on ten 16-core servers. Most of the discovered proteins are highly diverged from known proteins and originate from very sparsely sampled eukaryotic supergroups. Conclusion: The open-source (GPLv3) MetaEuk software (https://github.com/soedinglab/metaeuk) enables large-scale eukaryotic metagenomics through reference-based, sensitive taxonomic and functional annotation. %B bioRxiv %P 851964 %8 jan %G eng %U http://biorxiv.org/content/early/2019/11/25/851964.abstract %R 10.1101/851964 %0 Journal Article %J Phytochemistry %D 2019 %T NMR characterization and evaluation of antibacterial and antiobiofilm activity of organic extracts from stationary phase batch cultures of five marine microalgae (Dunaliella sp., D. salina, Chaetoceros calcitrans, C. gracilis and Tisochrysis lutea) %A Iglesias, Ma José %A Soengas, Raquel %A Probert, Ian %A Guilloud, Emilie %A Gourvil, Priscillia %A Mehiri, Mohamed %A López, Yuly %A Cepas, Virginio %A Gutiérrez-del-Río, Ignacio %A Redondo-Blanco, Saúl %A Villar, Claudio J. %A Lombó, Felipe %A Soto, Sara %A Ortiz, Fernando López %K Antibacterial %K Antibiofilm %K Chaetoceros %K Dunaliella %K Metabolite identification %K NMR %K RCC1349 %K RCC1811 %K RCC3579 %K RCC5 %K RCC5953 %K Tisochrysis %B Phytochemistry %V 164 %P 192–205 %8 aug %G eng %U https://linkinghub.elsevier.com/retrieve/pii/S0031942219300184 %R 10.1016/j.phytochem.2019.05.001 %0 Journal Article %J Limnology and Oceanography Letters %D 2019 %T Particulate inorganic to organic carbon production as a predictor for coccolithophorid sensitivity to ongoing ocean acidification %A Gafar, N. A. %A Eyre, B. D. %A Schulz, K. G. %K RCC1130 %K RCC1141 %K RCC1168 %K RCC1198 %K RCC1200 %K RCC1323 %K RCC1334 %X Ocean acidification (OA) can induce shifts in plankton community composition, with coccolithophores being mostly negatively impacted. This is likely to change particulate inorganic and organic carbon (PIC and POC, respectively) production, with impacts on the biological carbon pump. Hence, assessing and, most importantly, understanding species-specific sensitivities of coccolithophores is paramount. In a multispecies comparison, spanning more than two orders of magnitude in terms of POC and PIC production rates, among Calcidiscus leptoporus, Coccolithus pelagicus subsp. braarudii, Emiliania huxleyi, Gephyrocapsa oceanica, and Scyphosphaera apsteinii, we found that cellular PIC : POC was a good predictor for a species' OA sensitivity. This is likely related to the need for cellular pH homeostasis, which is challenged by the process of calcification producing protons internally, especially when seawater pH decreases in an OA scenario. With higher PIC : POC, species and strains being more sensitive to OA coccolithophores may shift toward less calcified varieties in the future. %B Limnology and Oceanography Letters %V 4 %P 62–70 %8 jun %G eng %U https://onlinelibrary.wiley.com/doi/abs/10.1002/lol2.10105 %R 10.1002/lol2.10105 %0 Journal Article %J The ISME Journal %D 2019 %T Picoeukaryotes of the Micromonas genus: sentinels of a warming ocean %A Demory, David %A Baudoux, Anne-claire %A Monier, Adam %A Simon, Nathalie %A Six, Christophe %A Ge, Pei %A Rigaut-jalabert, Fabienne %A Marie, Dominique %A Sciandra, Antoine %A Bernard, Olivier %A Rabouille, Sophie %K Biogeography %K change ecology %K Climate %K microbial ecology %K RCC114 %K RCC1697 %K RCC1862 %K RCC2257 %K RCC2306 %K RCC299 %K RCC451 %K RCC497 %K RCC746 %K RCC829 %K RCC834 %X Photosynthetic picoeukaryotesx in the genus Micromonas show among the widest latitudinal distributions on Earth, experiencing large thermal gradients from poles to tropics. Micromonas comprises at least four different species often found in sympatry. While such ubiquity might suggest a wide thermal niche, the temperature response of the different strains is still unexplored, leaving many questions as for their ecological success over such diverse ecosystems. Using combined experiments and theory, we characterize the thermal response of eleven Micromonas strains belonging to four species. We demonstrate that the variety of specific responses to temperature in the Micromonas genus makes this environmental factor an ideal marker to describe its global distribution and diversity. We then propose a diversity model for the genus Micromonas, which proves to be representative of the whole phytoplankton diversity. This prominent primary producer is therefore a sentinel organism of phytoplankton diversity at the global scale. We use the diversity within Micromonas to anticipate the potential impact of global warming on oceanic phytoplankton. We develop a dynamic, adaptive model and run forecast simulations, exploring a range of adaptation time scales, to probe the likely responses to climate change. Results stress how biodiversity erosion depends on the ability of organisms to adapt rapidly to temperature increase. %B The ISME Journal %V 13 %P 132–146 %8 jan %G eng %U http://www.nature.com/articles/s41396-018-0248-0 %R 10.1038/s41396-018-0248-0 %0 Journal Article %J Genes %D 2019 %T Simplified transformation of ostreococcus tauri using polyethylene glycol %A Sanchez, Frédéric %A Geffroy, Solène %A Norest, Manon %A Yau, Sheree %A Moreau, Hervé %A Grimsley, Nigel %K bioluminescence %K Chlorophyta %K Ecosystem %K Gene Expression %K luciferase %K mamiellophyceae %K Ostreococcus %K picoeukaryote %K plankton %K Prasinophyte %K promoter %K RCC4221 %X Ostreococcustauri is an easily cultured representative of unicellular algae (class Mamiellophyceae) that abound in oceans worldwide. Eight complete 13–22 Mb genomes of phylogenetically divergent species within this class are available, and their DNA sequences are nearly always present in metagenomic data produced from marine samples. Here we describe a simplified and robust transformation protocol for the smallest of these algae (O. tauri). Polyethylene glycol (PEG) treatment was much more efficient than the previously described electroporation protocol. Short (2 min or less) incubation times in PEG gave ¿104 transformants per microgram DNA. The time of cell recovery after transformation could be reduced to a few hours, permitting the experiment to be done in a day rather than overnight as used in previous protocols. DNA was randomly inserted in the O. tauri genome. In our hands PEG was 20–40-fold more efficient than electroporation for the transformation of O. tauri, and this improvement will facilitate mutagenesis of all of the dispensable genes present in the tiny O. tauri genome. %B Genes %V 10 %P 399 %8 may %G eng %U https://www.mdpi.com/2073-4425/10/5/399 %R 10.3390/genes10050399 %0 Journal Article %J The ISME Journal %D 2019 %T Taming chlorophylls by early eukaryotes underpinned algal interactions and the diversification of the eukaryotes on the oxygenated Earth %A Kashiyama, Yuichiro %A Yokoyama, Akiko %A Shiratori, Takashi %A Hess, Sebastian %A Not, Fabrice %A Bachy, Charles %A Gutierrez-Rodriguez, Andres %A Kawahara, Jun %A Suzaki, Toshinobu %A Nakazawa, Masami %A Ishikawa, Takahiro %A Maruyama, Moe %A Wang, Mengyun %A Chen, Man %A Gong, Yingchun %A Seto, Kensuke %A Kagami, Maiko %A Hamamoto, Yoko %A Honda, Daiske %A Umetani, Takahiro %A Shihongi, Akira %A Kayama, Motoki %A Matsuda, Toshiki %A Taira, Junya %A Yabuki, Akinori %A Tsuchiya, Masashi %A Hirakawa, Yoshihisa %A Kawaguchi, Akane %A Nomura, Mami %A Nakamura, Atsushi %A Namba, Noriaki %A Matsumoto, Mitsufumi %A Tanaka, Tsuyoshi %A Yoshino, Tomoko %A Higuchi, Rina %A Yamamoto, Akihiro %A Maruyama, Tadanobu %A Yamaguchi, Aika %A Uzuka, Akihiro %A Miyagishima, Shinya %A Tanifuji, Goro %A Kawachi, Masanobu %A Kinoshita, Yusuke %A Tamiaki, Hitoshi %K Biochemistry %K Biogeochemistry %K Cellular microbiology %K microbial ecology %K RCC164 %K RCC22 %K RCC24 %K RCC375 %K RCC916 %X Extant eukaryote ecology is primarily sustained by oxygenic photosynthesis, in which chlorophylls play essential roles. The exceptional photosensitivity of chlorophylls allows them to harvest solar energy for photosynthesis, but on the other hand, they also generate cytotoxic reactive oxygen species. A risk of such phototoxicity of the chlorophyll must become particularly prominent upon dynamic cellular interactions that potentially disrupt the mechanisms that are designed to quench photoexcited chlorophylls in the phototrophic cells. Extensive examination of a wide variety of phagotrophic, parasitic, and phototrophic microeukaryotes demonstrates that a catabolic process that converts chlorophylls into nonphotosensitive 132,173-cyclopheophorbide enols (CPEs) is phylogenetically ubiquitous among extant eukaryotes. The accumulation of CPEs is identified in phagotrophic algivores belonging to virtually all major eukaryotic assemblages with the exception of Archaeplastida, in which no algivorous species have been reported. In addition, accumulation of CPEs is revealed to be common among phototrophic microeukaryotes (i.e., microalgae) along with dismantling of their secondary chloroplasts. Thus, we infer that CPE-accumulating chlorophyll catabolism (CACC) primarily evolved among algivorous microeukaryotes to detoxify chlorophylls in an early stage of their evolution. Subsequently, it also underpinned photosynthetic endosymbiosis by securing close interactions with photosynthetic machinery containing abundant chlorophylls, which led to the acquisition of secondary chloroplasts. Our results strongly suggest that CACC, which allowed the consumption of oxygenic primary producers, ultimately permitted the successful radiation of the eukaryotes throughout and after the late Proterozoic global oxygenation. %B The ISME Journal %P 1 %8 feb %G eng %U http://www.nature.com/articles/s41396-019-0377-0 %R 10.1038/s41396-019-0377-0 %0 Journal Article %J Genome Biology and Evolution %D 2019 %T Tracing the evolution of the plastome and mitogenome in the chloropicophyceae uncovered convergent tRNA gene losses and a variant plastid genetic code %A Turmel, Monique %A dos Santos, Adriana Lopes %A Otis, Christian %A Sergerie, Roxanne %A Lemieux, Claude %E Archibald, John %K RCC15 %K RCC1871 %K RCC2335 %K RCC2339 %K RCC287 %K RCC3374 %K RCC3402 %K RCC4434 %K RCC4572 %K RCC4656 %K RCC696 %K RCC856 %K RCC998 %K RCC999 %B Genome Biology and Evolution %V in press %8 apr %G eng %U https://www.biorxiv.org/content/10.1101/530998v1 https://academic.oup.com/gbe/advance-article/doi/10.1093/gbe/evz074/5425330 %R 10.1093/gbe/evz074 %0 Journal Article %J New Phytologist %D 2019 %T Unveiling membrane thermoregulation strategies in marine picocyanobacteria %A Breton, Solène %A Jouhet, Juliette %A Guyet, Ulysse %A Gros, Valérie %A Pittera, Justine %A Demory, David %A Partensky, Frédéric %A Doré, Hugo %A Ratin, Morgane %A Maréchal, Éric %A Nguyen, Ngoc An %A Garczarek, Laurence %A Six, Christophe %K RCC2374 %K RCC2385 %K RCC515 %K rcc539 %B New Phytologist %P nph.16239 %8 oct %G eng %U https://onlinelibrary.wiley.com/doi/abs/10.1111/nph.16239 %R 10.1111/nph.16239 %0 Journal Article %J Nature Communications %D 2019 %T X-ray nanotomography of coccolithophores reveals that coccolith mass and segment number correlate with grid size %A Beuvier, T. %A Probert, I. %A Beaufort, L. %A Suchéras-Marx, B. %A Chushkin, Y. %A Zontone, F. %A Gibaud, A. %K Biomaterials %K Marine biology %K rcc1212 %K RCC1216 %K RCC1314 %K RCC3370 %K RCC4032 %K RCC4036 %X Coccolithophores of the Noëlaerhabdaceae family are covered by imbricated coccoliths, each composed of multiple calcite crystals radially distributed around the periphery of a grid. The factors that determine coccolith size remain obscure. Here, we used synchrotron-based three-dimensional Coherent X-ray Diffraction Imaging to study coccoliths of 7 species of Gephyrocapsa, Emiliania and Reticulofenestra with a resolution close to 30 nm. Segmentation of 45 coccoliths revealed remarkable size, mass and segment number variations, even within single coccospheres. In particular, we observed that coccolith mass correlates with grid perimeter which scales linearly with crystal number. Our results indirectly support the idea that coccolith mass is determined in the coccolith vesicle by the size of the organic base plate scale (OBPS) around which R-unit nucleation occurs every 110–120 nm. The curvation of coccoliths allows inference of a positive correlation between cell nucleus, OBPS and coccolith sizes. %B Nature Communications %V 10 %P 751 %8 dec %G eng %U http://www.nature.com/articles/s41467-019-08635-x %R 10.1038/s41467-019-08635-x %0 Journal Article %J GigaScience %D 2018 %T 10KP: A phylodiverse genome sequencing plan %A Cheng, Shifeng %A Melkonian, Michael %A Smith, Stephen A %A Brockington, Samuel %A Archibald, John M %A Delaux, Pierre-Marc %A Li, Fay-Wei %A Melkonian, Barbara %A Mavrodiev, Evgeny V %A Sun, Wenjing %A Fu, Yuan %A Yang, Huanming %A Soltis, Douglas E %A Graham, Sean W %A Soltis, Pamela S %A Liu, Xin %A Xu, Xun %A Wong, Gane Ka-Shu %K 10kp %K 12 february 2018 %K 2018 %K 4 %K accepted %K access article distributed under %K and reproduction in any %K attribution license %K biodiversity %K by %K c the author %K creative commons %K creativecommons %K Distribution %K genome sequencing %K genomics %K http %K licenses %K medium %K mgiseq %K open community %K org %K phylogenomics %K PLANTS %K press %K published by oxford university %K received %K s %K samples %K the terms of the %K this is an open %K which permits unrestricted reuse %B GigaScience %V 7 %P 1–9 %G eng %U https://academic.oup.com/gigascience/article/7/3/1/4880447 %R 10.1093/gigascience/giy013 %0 Journal Article %J Molecular Ecology %D 2018 %T Analysis of the genomic basis of functional diversity in dinoflagellates using a transcriptome-based sequence similarity network %A Meng, Arnaud %A Corre, Erwan %A Probert, Ian %A Gutierrez-Rodriguez, Andres %A Siano, Raffaele %A Annamale, Anita %A Alberti, Adriana %A Da Silva, Corinne %A Wincker, Patrick %A Le Crom, Stéphane %A Not, Fabrice %A Bittner, Lucie %K Genomics/Proteomics %K Microbial Biology %K Molecular Evolution %K Protists %K rcc1491 %K RCC1516 %K RCC3387 %K rcc3468 %K rcc3507 %K transcriptomics %X Dinoflagellates are one of the most abundant and functionally diverse groups of eukaryotes. Despite an overall scarcity of genomic information for dinoflagellates, constantly emerging high-throughput sequencing resources can be used to characterize and compare these organisms. We assembled de novo and processed 46 dinoflagellate transcriptomes and used a sequence similarity network (SSN) to compare the underlying genomic basis of functional features within the group. This approach constitutes the most comprehensive picture to date of the genomic potential of dinoflagellates. A core predicted proteome composed of 252 connected components (CCs) of putative conserved protein domains (pCDs) was identified. Of these, 206 were novel and 16 lacked any functional annotation in public databases. Integration of functional information in our network analyses allowed investigation of pCDs specifically associated to functional traits. With respect to toxicity, sequences homologous to those of proteins found in species with toxicity potential (e.g. sxtA4 and sxtG) were not specific to known toxin-producing species. Although not fully specific to symbiosis, the most represented functions associated with proteins involved in the symbiotic trait were related to membrane processes and ion transport. Overall, our SSN approach led to identification of 45,207 and 90,794 specific and constitutive pCDs of respectively the toxic and symbiotic species represented in our analyses. Of these, 56% and 57% respectively (i.e. 25,393 and 52,193 pCDs) completely lacked annotation in public databases. This stresses the extent of our lack of knowledge, while emphasizing the potential of SSNs to identify candidate pCDs for further functional genomic characterization. This article is protected by copyright. All rights reserved. %B Molecular Ecology %P 0–2 %G eng %U http://www.ncbi.nlm.nih.gov/pubmed/29624751%0Ahttp://doi.wiley.com/10.1111/mec.14579 %R 10.1111/mec.14579 %0 Journal Article %J Frontiers in Marine Science %D 2018 %T Bolidophyceae, a sister picoplanktonic group of diatoms – a review %A Kuwata, Akira %A Yamada, Kazumasa %A Ichinomiya, Mutsuo %A Yoshikawa, Shinya %A Tragin, Margot %A Vaulot, Daniel %A Lopes dos Santos, Adriana %K RCC1657 %K RCC201 %K RCC205 %K RCC206 %K rcc212 %K RCC239 %B Frontiers in Marine Science %V 5 %P 370 %8 oct %G eng %U https://www.frontiersin.org/article/10.3389/fmars.2018.00370/full %R 10.3389/fmars.2018.00370 %0 Journal Article %J Scientific Reports %D 2018 %T Carboxythiazole is a key microbial nutrient currency and critical component of thiamin biosynthesis %A Paerl, Ryan W. %A Bertrand, Erin M. %A Rowland, Elden %A Schatt, Phillippe %A Mehiri, Mohamed %A Niehaus, Thomas D. %A Hanson, Andrew D. %A Riemann, Lasse %A Yves-Bouget, Francois %K RCC4222 %K RCC745 %B Scientific Reports %V 8 %P 5940 %G eng %U http://www.nature.com/articles/s41598-018-24321-2 %R 10.1038/s41598-018-24321-2 %0 Journal Article %J Marine Drugs %D 2018 %T Comparative analysis of culture conditions for the optimization of carotenoid production in several strains of the picoeukaryote ostreococcus %A Guyon, Jean-baptiste %A Schatt, Philippe %A Lozano, Jean-Claude %A Liennard, Marion %A Bouget, François-Yves %K 2018 %K carotenoids %K GROWTH RATE %K Light %K Ostreococcus %K rcc %K RCC745 %K RCC802 %K RCC809 %K salinity %K temperature %X Microalgae are promising sources for the sustainable production of compounds of interest for biotechnologies. Compared to higher plants, microalgae have a faster growth rate and can be grown in industrial photobioreactors. The microalgae biomass contains specific metabolites of high added value for biotechnology such as lipids, polysaccharides or carotenoid pigments. Studying carotenogenesis is important for deciphering the mechanisms of adaptation to stress tolerance as well as for biotechnological production. In recent years, the picoeukaryote Ostreococcus tauri has emerged as a model organism thanks to the development of powerful genetic tools. Several strains of Ostreococcus isolated from different environments have been characterized with respect to light response or iron requirement. We have compared the carotenoid contents and growth rates of strains of Ostreococcus (OTTH595, RCC802 and RCC809) under a wide range of light, salinity and temperature conditions. Carotenoid profiles and productivities varied in a strain-specific and stress-dependent manner. Our results also illustrate that phylogenetically related microalgal strains originating from different ecological niches present specific interests for the production of specific molecules under controlled culture conditions. %B Marine Drugs %V 16 %P 76 %G eng %U http://www.mdpi.com/1660-3397/16/3/76 %R 10.3390/md16030076 %0 Journal Article %J Photosynthesis Research %D 2018 %T Comparison of photosynthetic performances of marine picocyanobacteria with different configurations of the oxygen-evolving complex %A Partensky, Frédéric %A Mella-Flores, Daniella %A Six, Christophe %A Garczarek, Laurence %A Czjzek, Mirjam %A Marie, Dominique %A Kotabová, Eva %A Felcmanová, Kristina %A Prášil, Ondřej %K rcc752 %X The extrinsic PsbU and PsbV proteins are known to play a critical role in stabilizing the Mn4CaO5 cluster of the PSII oxygen-evolving complex (OEC). However, most isolates of the marine cyanobacterium Prochlorococcus naturally miss these proteins, even though they have kept the main OEC protein, PsbO. A structural homology model of the PSII of such a natural deletion mutant strain (P. marinus MED4) did not reveal any obvious compensation mechanism for this lack. To assess the physiological consequences of this unusual OEC, we compared oxygen evolution between Prochlorococcus strains missing psbU and psbV (PCC 9511 and SS120) and two marine strains possessing these genes (Prochlorococcus sp. MIT9313 and Synechococcus sp. WH7803). While the low light-adapted strain SS120 exhibited the lowest maximal O2 evolution rates (Pmax per divinyl-chlorophyll a, per cell or per photosystem II) of all four strains, the high light-adapted strain PCC 9511 displayed even higher PChlmax and PPSIImax at high irradiance than Synechococcus sp. WH7803. Furthermore, thermoluminescence glow curves did not show any alteration in the B-band shape or peak position that could be related to the lack of these extrinsic proteins. This suggests an efficient functional adaptation of the OEC in these natural deletion mutants, in which PsbO alone is seemingly sufficient to ensure proper oxygen evolution. Our study also showed that Prochlorococcus strains exhibit negative net O2 evolution rates at the low irradiances encountered in minimum oxygen zones, possibly explaining the very low O2 concentrations measured in these environments, where Prochlorococcus is the dominant oxyphototroph. %B Photosynthesis Research %V 138 %P 57–71 %G eng %U https://doi.org/10.1007/s11120-018-0539-3 %R 10.1007/s11120-018-0539-3 %0 Journal Article %J Harmful Algae %D 2018 %T Development of a qPCR assay to detect and quantify ichthyotoxic flagellates along the Norwegian coast, and the first Norwegian record of Fibrocapsa japonica (Raphidophyceae) %A Engesmo, Anette %A Strand, David %A Gran-Stadniczeñko, Sandra %A Edvardsen, Bente %A Medlin, Linda K. %A Eikrem, Wenche %K 454 high throughput environmental sequencing %K Heterosigma akashiwo %K Karenia mikimotoi %K Karlodinium veneficum %K Molecular monitoring %K rcc1501 %K rcc1502 %K RDNA %K SEM %X Blooms of ichthyotoxic microalgae pose a great challenge to the aquaculture industry world-wide, and there is a need for fast and specific methods for their detection and quantification in monitoring programs. In this study, quantitative real-time PCR (qPCR) assays for the detection and enumeration of three ichthyotoxic flagellates: the dinoflagellate Karenia mikimotoi (Miyake & Kominami ex Oda) Hansen & Moestrup and the two raphidophytes Heterosigma akashiwo (Hada) Hada ex Hara & Chihara and Fibrocapsa japonica Toriumi & Takano were developed. Further, a previously published qPCR assay for the dinoflagellate Karlodinium veneficum (Ballantine) Larsen was used. Monthly samples collected for three years (Aug 2009–Jun 2012) in outer Oslofjorden, Norway were analysed, and the results compared with light microscopy cell counts. The results indicate a higher sensitivity and a lower detection limit (down to 1 cell L-1) for both qPCR assays. Qualitative and semi-quantitative results were further compared with those obtained by environmental 454 high throughput sequencing (HTS, metabarcoding) and scanning electron microscopy (SEM) examination from the same samplings. All four species were detected by qPCR and HTS and/or SEM in outer Oslofjorden (Aug 2009–Jun 2012); Karlodinium veneficum was present year-round, whereas Karenia mikimotoi, Heterosigma akashiwo and Fibrocapsa japonica appeared mainly during the autumn in all three years. This is the first observation of Fibrocapsa japonica in Norwegian coastal waters. This species has previously been recorded off the Swedish west coast and German Bight, which may suggest a northward dispersal. %B Harmful Algae %V 75 %P 105–117 %G eng %U https://doi.org/10.1016/j.hal.2018.04.007 %R 10.1016/j.hal.2018.04.007 %0 Journal Article %J Science Advances %D 2018 %T Endocytosis-mediated siderophore uptake as a strategy for Fe acquisition in diatoms %A Kazamia, Elena %A Sutak, Robert %A Paz-Yepes, Javier %A Dorrell, Richard G %A Vieira, Fabio Rocha Jimenez %A Mach, Jan %A Morrissey, Joe %A Leon, Sébastien %A Lam, France %A Pelletier, Eric %A Camadro, Jean-michel %A Bowler, Chris %A Lesuisse, Emmanuel %K RCC2967 %B Science Advances %V 4 %P eaar4536 %8 may %G eng %U http://advances.sciencemag.org/lookup/doi/10.1126/sciadv.aar4536 %R 10.1126/sciadv.aar4536 %0 Journal Article %J Frontiers in Microbiology %D 2018 %T High variability in cellular stoichiometry of carbon, nitrogen, and phosphorus within classes of marine eukaryotic phytoplankton under sufficient nutrient conditions %A Garcia, Nathan S. %A Sexton, Julie %A Riggins, Tracey %A Brown, Jeff %A Lomas, Michael W. %A Martiny, Adam C. %K cell size %K Diatom %K Dinoflagellate %K eukaryote %K frontiers in microbiology %K frontiersin %K Growth %K org %K protist %K prymnesiophyte %K RCC103 %K RCC1242 %K RCC1562 %K RCC4023 %K RCC449 %K RCC931 %K temperature %K www %X Current hypotheses suggest that cellular elemental stoichiometry of marine eukaryotic phytoplankton such as the ratios of cellular carbon:nitrogen:phosphorus (C:N:P) vary between phylogenetic groups based traits like evolutionary history and cell size. To investigate how phylogenetic structure, cell volume, growth rate and temperature interact to affect the cellular elemental stoichiometry of marine eukaryotic phytoplankton, we examined the C:N:P composition in 30 isolates across 7 classes of marine phytoplankton that were grown with a sufficient supply of nutrients with nitrate as the nitrogen source. The isolates covered a wide range in cell volume (5 orders of magnitude), growth rate (¡0.01-0.9 d-1), and habitat temperature (2-24°C). Our analysis indicates that C:N:P is highly variable, with statistical model residuals accounting for over half of the total variance with no relationship between phylogeny and elemental stoichiometry. Furthermore, our data indicated that variability in C:P, N:P and C:N within Bacillariophyceae (diatoms) was as high as that among all of the isolates that we examined. In addition, a linear statistical model identified a positive relationship between diatom cell volume and C:P and N:P. Among all of the isolates that we examined, the statistical model identified temperature as a significant factor, consistent with the temperature-dependent translation efficiency model, but temperature only explained 5% of the total statistical model variance. While some of our results support data from previous field studies, the high variability of elemental ratios within Bacillariophyceae contradicts previous work that suggests that this cosmopolitan group of microalgae has consistently low C:P and N:P ratios in comparison with other groups. %B Frontiers in Microbiology %V 9 %P 1–10 %G eng %U http://journal.frontiersin.org/article/10.3389/fmicb.2018.00543/full %R 10.3389/fmicb.2018.00543 %0 Journal Article %J iScience %D 2018 %T Infection dynamics of a bloom-forming alga and its virus determine airborne coccolith emission from seawater %A Trainic, Miri %A Koren, Ilan %A Sharoni, Shlomit %A Frada, Miguel %A Segev, Lior %A Rudich, Yinon %A Vardi, Assaf %K Atmospheric Science %K Biogeoscience %K Earth Sciences %K Marine Organism %K RCC1216 %X Summary Sea spray aerosols (SSA), have a profound effect on the climate; however, the contribution of oceanic microbial activity to SSA is not fully established. We assessed aerosolization of the calcite units (coccoliths) that compose the exoskeleton of the cosmopolitan bloom-forming coccolithophore, Emiliania huxleyi. Airborne coccolith emission occurs in steady-state conditions and increases by an order of magnitude during E. huxleyi infection by E. huxleyi virus (EhV). Airborne to seawater coccolith ratio is 1:108, providing estimation of airborne concentrations from seawater concentrations. The coccoliths' unique aerodynamic structure yields a characteristic settling velocity of \~0.01 cm s-1, \~25 times slower than average sea salt particles, resulting in coccolith fraction enrichment in the air. The calculated enrichment was established experimentally, indicating that coccoliths may be key contributors to coarse mode SSA surface area, comparable with sea salt aerosols. This study suggests a coupling between key oceanic microbial interactions and fundamental atmospheric processes like SSA formation. %B iScience %8 aug %G eng %U https://www.cell.com/iscience/fulltext/S2589-0042(18)30105-6 https://linkinghub.elsevier.com/retrieve/pii/S2589004218301056 %R 10.1016/j.isci.2018.07.017 %0 Journal Article %J bioRxiv %D 2018 %T Integrated systems biology and imaging of the smallest free-living eukaryote Ostreococcus tauri %A Smallwood, Authors Chuck R %A Chen, Jian-hua %A Kumar, Neeraj %A Chrisler, William %A Samuel, O %A Kyle, Jennifer E %A Nicora, Carrie D %A Boudreau, Rosanne %A Ekman, Axel %A Kim, K %A Moore, Ronald J %A Mcdermott, Gerry %A Cannon, William R %A Evans, James E %K ? No DOI found %K RCC745 %B bioRxiv %G eng %0 Journal Article %J Proceedings of the National Academy of Sciences %D 2018 %T Light color acclimation is a key process in the global ocean distribution of Synechococcus cyanobacteria %A Grébert, Théophile %A Doré, Hugo %A Partensky, Frédéric %A Farrant, Gregory K. %A Boss, Emmanuel S. %A Picheral, Marc %A Guidi, Lionel %A Pesant, Stéphane %A Scanlan, David J. %A Wincker, Patrick %A Acinas, Silvia G. %A Kehoe, David M. %A Garczarek, Laurence %K 2018 %K RCC1016 %K RCC1017 %K RCC1018 %K RCC1020 %K RCC1023 %K RCC1027 %K RCC1030 %K RCC1031 %K rcc1084 %K RCC1085 %K RCC1086 %K RCC1087 %K RCC1096 %K RCC1097 %K RCC1649 %K RCC1661 %K RCC1688 %K RCC2032 %K RCC2033 %K RCC2035 %K RCC2319 %K RCC2366 %K RCC2368 %K RCC2369 %K RCC2370 %K RCC2372 %K RCC2373 %K RCC2374 %K RCC2375 %K RCC2376 %K RCC2378 %K RCC2379 %K rcc2380 %K RCC2381 %K rcc2382 %K RCC2383 %K RCC2384 %K RCC2385 %K RCC2415 %K RCC2432 %K RCC2433 %K RCC2434 %K RCC2435 %K RCC2436 %K RCC2437 %K RCC2438 %K RCC2457 %K RCC2525 %K RCC2526 %K RCC2527 %K RCC2528 %K RCC2529 %K RCC2530 %K RCC2532 %K RCC2533 %K RCC2534 %K RCC2536 %K RCC2553 %K RCC2554 %K RCC2555 %K RCC2556 %K RCC2567 %K RCC2568 %K RCC2569 %K RCC2570 %K RCC2571 %K RCC2673 %K rcc30 %K RCC3010 %K RCC3012 %K RCC3014 %K RCC307 %K RCC316 %K RCC318 %K RCC325 %K RCC326 %K RCC328 %K RCC37 %K RCC44 %K RCC46 %K RCC47 %K RCC515 %K rcc539 %K RCC542 %K RCC543 %K RCC550 %K RCC552 %K RCC553 %K rcc555 %K RCC556 %K RCC557 %K RCC558 %K RCC559 %K RCC62 %K RCC650 %K RCC66 %K rcc752 %K RCC753 %K RCC790 %K rcc791 %K RCC792 %K RCC793 %K RCC794 %K sbr?hyto?app %X Marine Synechococcus cyanobacteria are major contributors to global oceanic primary production and exhibit a unique diversity of photosynthetic pigments, allowing them to exploit a wide range of light niches. However, the relationship between pigment content and niche partitioning has remained largely undetermined so far due to the lack of a single-genetic marker resolving all pigment types (PT). Here, we developed a novel and robust method based on three distinct marker genes to estimate the relative abundance of all Synechococcus PTs from metagenomes. Analysis of the Tara Oceans dataset allowed us to unveil for the first time the global distribution of Synechococcus PTs and to decipher their realized environmental niches. Green-light specialists (PT 3a) dominated in warm, green equatorial waters, whereas blue-light specialists (PT 3c) were particularly abundant in oligotrophic areas. Type IV chromatic acclimaters (CA4-A/B), which are able to dynamically modify their light absorption properties to maximally absorb green or blue light, were unexpectedly the most abundant PT in our dataset and predominated at depth and high latitudes. We also identified local populations in which CA4 might be inactive due to the lack of specific CA4 genes, notably in warm high nutrient low chlorophyll areas. Major ecotypes within clades I-IV and CRD1 were preferentially associated with a particular PT, while others exhibited a wide range of PTs. Altogether, this study brings unprecedented insights into the ecology of Synechococcus PTs and highlights the complex interactions between vertical phylogeny, pigmentation and environmental parameters that shape Synechococcus populations and evolution. %B Proceedings of the National Academy of Sciences %V in press %P 201717069 %8 feb %G eng %U http://www.pnas.org/lookup/doi/10.1073/pnas.1717069115 %R 10.1073/pnas.1717069115 %0 Journal Article %J Scientific Reports %D 2018 %T A novel species of the marine cyanobacterium Acaryochloris with a unique pigment content and lifestyle %A Partensky, Frédéric %A Six, Christophe %A Ratin, Morgane %A Garczarek, Laurence %A Vaulot, Daniel %A Probert, Ian %A Calteau, Alexandra %A Gourvil, Priscillia %A Marie, Dominique %A Grébert, Théophile %A Bouchier, Christiane %A Le Panse, Sophie %A Gachenot, Martin %A Rodríguez, Francisco %A Garrido, José L. %K RCC1774 %B Scientific Reports %V 8 %P 9142 %8 dec %G eng %U http://www.nature.com/articles/s41598-018-27542-7 %R 10.1038/s41598-018-27542-7 %0 Journal Article %J Journal of Phycology %D 2018 %T Ontogenetic analysis of siliceous cell wall formation in Triparma laevis f. inornata (Parmales, Stramenopiles) %A Yamada, Kazumasa %A Katsura, Hirotaka %A Noël, Mary-Hélène %A Ichinomiya, Mutsuo %A Kuwata, Akira %A Sato, Shinya %A Yoshikawa, Shinya %K RCC4665 %B Journal of Phycology %P 0–2 %8 oct %G eng %U http://doi.wiley.com/10.1111/jpy.12800 %R 10.1111/jpy.12800 %0 Journal Article %J bioRxiv %D 2018 %T Phenotypic variability in chloroplast redox state predicts cell fate in a marine diatom %A Mizrachi, Avia %A Graff, Shiri %A Creveld, Van %A Shapiro, Orr H %A Rosenwasser, Shilo %K RCC2967 %B bioRxiv %G eng %R 10.1101/319517 %0 Journal Article %J bioRxiv %D 2018 %T A phosphate starvation response gene (psr1-like) is present and expressed in Micromonas pusilla and other marine algae %A Fiore, Cara L. %A Alexander, Harriet %A Soule, Melissa C. Kido %A Kujawinski, Elizabeth B. %K ? No DOI found %K RCC299 %K RCC834 %B bioRxiv %G eng %U http://dx.doi.org/10.1101/484824 %0 Journal Article %J Environmental Microbiology Reports %D 2018 %T Relative stability of ploidy in a marine Synechococcus across various growth conditions %A Perez-Sepulveda, Blanca %A Pitt, Frances %A N'Guyen, An Ngoc %A Ratin, Morgane %A Garczarek, Laurence %A Millard, Andrew %A Scanlan, David J %K rcc752 %X Marine picocyanobacteria of the genus Synechococcus are ubiquitous phototrophs in oceanic systems. Consistent with these organisms occupying vast tracts of the nutrient impoverished ocean, most marine Synechococcus so far studied are monoploid i.e. contain a single chromosome copy. The exception is the oligoploid strain Synechococcus sp. WH7803, which on average possesses around 4 chromosome copies. Here, we set out to understand the role of resource availability (through nutrient deplete growth) and physical stressors (UV, exposure to low and high temperature) in regulating ploidy level in this strain. Using qPCR to assay ploidy status we demonstrate the relative stability of chromosome copy number in Synechococcus sp. WH7803. Such robustness in maintaining an oligoploid status even under nutrient and physical stress is indicative of a fundamental role, perhaps facilitating recombination of damaged DNA regions as a result of prolonged exposure to oxidative stress, or allowing added flexibility in gene expression via possessing multiple alleles. This article is protected by copyright. All rights reserved. %B Environmental Microbiology Reports %P in press %8 feb %G eng %U http://dx.doi.org/10.1111/1758-2229.12614 http://doi.wiley.com/10.1111/1758-2229.12614 %R 10.1111/1758-2229.12614 %0 Journal Article %J Frontiers in Microbiology %D 2017 %T Adaptation to blue light in marine synechococcus requires MpeU, an enzyme with similarity to phycoerythrobilin lyase isomerases %A Mahmoud, Rania M. %A Sanfilippo, Joseph E. %A Nguyen, Adam A. %A Strnat, Johann A. %A Partensky, Frédéric %A Garczarek, Laurence %A Abo El Kassem, Nabil %A Kehoe, David M. %A Schluchter, Wendy M. %K 2017 %K Blue light %K light harvesting complex %K Lyase isomerase %K marine cyanobacteria %K Marine Synechococcus %K phycobilin %K Phycobilisome %K Phycoerythrin %K Phycourobilin %K rcc555 %K sbr?hyto?app %X Marine Synechococcus cyanobacteria have successfully adapted to environments with different light colors, which likely contributes to this genus being the second most abundant photosynthetic microorganism worldwide. Populations of Synechococcus that grow in deep, blue ocean waters contain large amounts of the blue-light absorbing chromophore phycourobilin (PUB) in their light harvesting complexes (phycobilisomes). Here we show that all Synechococcus strains adapted to blue light possess a gene called mpeU. MpeU is structurally similar to phycobilin lyases, enzymes that ligate chromophores to phycobiliproteins. Interruption of mpeU caused a reduction in PUB content, produced impaired phycobilisomes and reduced growth rate more strongly in blue than green light. When mpeU was reintroduced in the mpeU mutant background, the mpeU-less phenotype was complemented in terms of PUB content and phycobilisome content. Fluorescence spectra of mpeU mutant cells and purified phycobilisomes revealed red-shifted phycoerythrin emission peaks, likely indicating a defect in chromophore ligation to phycoerythrin-I (PE-I) or phycoerythrin-II (PE-II). Our results suggest that MpeU is a lyase-isomerase that attaches a phycoerythrobilin to a PEI or PEII subunit and isomerizes it to PUB. MpeU is therefore an important determinant in adaptation of Synechococcus spp. to capture photons in blue light environments throughout the world's oceans. %B Frontiers in Microbiology %V 8 %P 243 %8 feb %G eng %U http://journal.frontiersin.org/article/10.3389/fmicb.2017.00243/full %R 10.3389/fmicb.2017.00243 %0 Journal Article %J The ISME Journal %D 2017 %T Adaptive thermostability of light-harvesting complexes in marine picocyanobacteria %A Pittera, Justine %A Partensky, Frédéric %A Six, Christophe %K 2016 %K rcc1594 %K rcc1682 %K rcc2380 %K rcc2382 %K rcc752 %K rcc791 %B The ISME Journal %V 11 %P 112–124 %G eng %U http://www.nature.com/doifinder/10.1038/ismej.2016.102 %R 10.1038/ismej.2016.102 %0 Journal Article %J Phycologia %D 2017 %T Adenoides sinensis , a new sand-dwelling dinoflagellate species from China and reexamination of A. eludens from an Atlantic strain %A Gu, Haifeng %A Li, Xintian %A Chomérat, Nicolas %A Luo, Zhaohe %A Sarno, Diana %A Gourvil, Priscillia %A Balzano, Sergio %A Siano, Raffaele %K 2017 %K rcc %K RCC1982 %K sbr?hyto$_\textrmd$ipo %X The sand-dwelling?1dinoflagellate generaAdenoidesandPseudadenoidesare morphologically very close butdistinct in their molecular phylogeny. We established three cultures by isolating single cells from sand samples collected inintertidal zones of Qingdao (Yellow Sea), Dongshan (South China Sea) and Brittany (English Channel, North Atlantic,France). Strain morphology was examined with light and scanning electron microscopy, and both large subunitribosomal DNA (LSU rDNA) and small subunit ribosomal DNA (SSU rDNA) sequences were amplified. Molecularphylogeny, corroborated by morphological examination showing the existence of a ventral pore, confirmed theidentification of the French strain (RCC1982) asAdenoides eludens. The Chinese strains differed fromAdenoides eludensin two additional posterior intercalary plates and differed fromPseudadenoidesin one additional apical plate having theplate formula of Po, Cp, X, 50,600, 4S, 5000, 5p, 10000or alternatively Po, Cp, X, 50,600, 5S, 5000, 3p, 20000. Maximumlikelihood and Bayesian inference carried out with concatenated LSU and SSU sequences demonstrated that the Chinesestrains were closely related but different fromA. eludensand, in corroboration with morphological evidence, supportedtheir classification as a distinct species,Adenoides sinensis sp. nov. Morphological and molecular results confirmed theclose relationship between the two generaAdenoidesandPseudadenoides. %B Phycologia %V 57 %P 1–13 %G eng %R 10.2216/17-76.1 %0 Journal Article %J Aquaculture Research %D 2017 %T Changes in fatty acids profile, monosaccharide profile and protein content during batch growth of Isochrysis galbana (T.iso) %A Gnouma, Asma %A Sadovskaya, Irina %A Souissi, Anissa %A Sebai, Khaled %A Medhioub, Amel %A Grard, Thierry %A Souissi, Sami %K fatty acids %K growth phases %K Isochrysis galbana (T.iso) %K monosaccharides %K proteins %K RCC1349 %X Abstract To investigate the nutritional value of the marine micro-alga Isochrysis galbana Tahitian Isochrysis strain (T.iso) as an alternative feed for aquaculture during culture age, its biochemical composition was studied under autotrophic and controlled culture conditions at different growth stages: exponential phase, early and late stationary phases and decay phase. Analysis showed that C14:0, C16:0, C16:1, C18:4 (n-3) and C22:6 (n-3) were the most abundant fatty acids in this alga at different growth stages. The highest values of monounsaturated fatty acids were recorded at the late stationary and the decay phases. However, the highest levels of polyunsaturated fatty acids were observed at the early stationary phase. At all growth stages, I. galbana (T.iso) contained arabinose, xylose, mannose, galactose and glucose. Glucose represented the main sugar, and its content per dry alga biomass weight increased with increasing age of the culture and reached about fourfold in the decay phase. The maximum protein content was also observed during this last phase. %B Aquaculture Research %V 48 %P 4982–4990 %8 sep %G eng %U https://doi.org/10.1111/are.13316 %R 10.1111/are.13316 %0 Journal Article %J Scientific Reports %D 2017 %T Chloropicophyceae, a new class of picophytoplanktonic prasinophytes %A Lopes dos Santos, Adriana %A Pollina, Thibaut %A Gourvil, Priscillia %A Corre, Erwan %A Marie, Dominique %A Garrido, José Luis %A Rodríguez, Francisco %A Noël, Mary-Hélène %A Vaulot, Daniel %A Eikrem, Wenche %K 2017 %K RCC1019 %K RCC1021 %K RCC1032 %K RCC1043 %K RCC1124 %K RCC138 %K RCC15 %K RCC1871 %K RCC19 %K RCC227 %K RCC2335 %K RCC2337 %K RCC2339 %K RCC287 %K RCC297 %K RCC3368 %K RCC3373 %K RCC3374 %K RCC3375 %K RCC3376 %K RCC3402 %K RCC4429 %K RCC4430 %K RCC4434 %K RCC4572 %K RCC4656 %K RCC696 %K RCC700 %K RCC701 %K RCC712 %K RCC713 %K RCC717 %K RCC719 %K RCC722 %K RCC726 %K RCC856 %K RCC857 %K RCC887 %K RCC917 %K RCC996 %K RCC997 %K RCC998 %K RCC999 %K sbr?hyto$_\textrmd$ipo %B Scientific Reports %V 7 %P 14019 %8 dec %G eng %U http://www.nature.com/articles/s41598-017-12412-5 %R 10.1038/s41598-017-12412-5 %0 Journal Article %J Journal of Phycology %D 2017 %T Comparative DNA sequence analyses of Pyramimonas parkeae (Prasinophyceae) chloroplast genomes %A Satjarak, Anchittha %A Graham, Linda E. %E Wood, M. %K RCC1987 %K RCC2009 %K RCC2015 %K RCC2500 %K RCC2501 %K RCC2502 %K RCC619 %B Journal of Phycology %V 53 %P 415–424 %8 apr %G eng %U http://doi.wiley.com/10.1111/jpy.12515 %R 10.1111/jpy.12515 %0 Journal Article %J Environmental Microbiology %D 2017 %T Copper toxicity response influences mesotrophic S ynechococcus community structure %A Stuart, Rhona K. %A Bundy, Randelle %A Buck, Kristen %A Ghassemain, Majid %A Barbeau, Kathy %A Palenik, Brian %K 2016 %K alkylsuccinate %K methanogenic %K n -alkane %K paraffin %K RCC1086 %K RCC2673 %K smithella %K syntrophy %X Picocyanobacteria from the genus Synechococcus are ubiquitous in ocean waters. Their phylogenetic and genomic diversity suggests ecological niche differentiation, but the selective forces influencing this are not well defined. Marine picocyanobacteria are sensitive to Cu toxicity, so adaptations to this stress could represent a selective force within, and between, “species” also known as clades. We compared Cu stress responses in cultures and natural populations of marine Synechococcus from two co-occurring major mesotrophic clades (I and IV). Using custom microarrays and proteomics to characterize expression responses to Cu in the lab and field, we found evidence for a general stress regulon in marine Synechococcus. However, the two clades also exhibited distinct responses to copper. The Clade I representative induced expression of genomic island genes in cultures and Southern California Bight populations, while the Clade IV representative downregulated Fe-limitation proteins. Copper incubation experiments suggest that Clade IV populations may harbor stress-tolerant subgroups, and thus fitness tradeoffs may govern Cu-tolerant strain distributions. This work demonstrates that Synechococcus has distinct adaptive strategies to deal with Cu toxicity at both the clade and subclade level, implying that metal toxicity and stress response adaptations represent an important selective force for influencing diversity within marine Synechococcus populations. This %B Environmental Microbiology %V 19 %P 756–769 %8 feb %G eng %U http://doi.wiley.com/10.1111/1462-2920.13630 %R 10.1111/1462-2920.13630 %0 Journal Article %J Limnology and Oceanography %D 2017 %T Dimethylated sulfur compounds in symbiotic protists: A potentially significant source for marine DMS(P) %A Gutierrez-Rodriguez, Andres %A Pillet, Loic %A Biard, Tristan %A Said-Ahmad, Ward %A Amrani, Alon %A Simó, Rafel %A Not, Fabrice %K 2017 %K rcc1383 %K rcc1491 %K rcc3468 %K rcc3507 %K sbr?hyto$_\textrmd$ipo %B Limnology and Oceanography %8 feb %G eng %U http://doi.wiley.com/10.1002/lno.10491 %R 10.1002/lno.10491 %0 Journal Article %J The ISME Journal %D 2017 %T Diversity and oceanic distribution of prasinophytes clade VII, the dominant group of green algae in oceanic waters %A Lopes dos Santos, Adriana %A Gourvil, Priscillia %A Tragin, Margot %A Noël, Mary-Hélène %A Decelle, Johan %A Romac, Sarah %A Vaulot, Daniel %K 2016 %K MACUMBA %K MicroB3 %K RCC1019 %K RCC1021 %K RCC1032 %K RCC1043 %K RCC1124 %K RCC138 %K RCC15 %K RCC1871 %K RCC19 %K RCC227 %K RCC2335 %K RCC2337 %K RCC2339 %K RCC287 %K RCC297 %K RCC3368 %K RCC3373 %K RCC3374 %K RCC3375 %K RCC3376 %K RCC3402 %K RCC4429 %K RCC4430 %K RCC4434 %K RCC4656 %K RCC696 %K RCC700 %K RCC701 %K RCC712 %K RCC713 %K RCC717 %K RCC719 %K RCC722 %K RCC726 %K RCC856 %K RCC857 %K RCC917 %K RCC996 %K RCC997 %K RCC998 %K RCC999 %K sbr?hyto$_\textrmd$ipo %K sbr?hyto?ppo %B The ISME Journal %V 11 %P 512–528 %8 feb %G eng %U http://www.nature.com/doifinder/10.1038/ismej.2016.120 %R 10.1038/ismej.2016.120 %0 Journal Article %J Frontiers in Microbiology %D 2017 %T Ecogenomics and taxonomy of cyanobacteria phylum %A Walter, Juline M. %A Coutinho, Felipe H. %A Dutilh, Bas E. %A Swings, Jean %A Thompson, Fabiano L. %A Thompson, Cristiane C. %K charting biodiversity %K ecological niches %K genome-based microbial taxonomy %K high-throughput sequencing technology %K metagenome %K microbial ecology %K RCC307 %B Frontiers in Microbiology %V 8 %8 nov %G eng %U http://journal.frontiersin.org/article/10.3389/fmicb.2017.02132/full %R 10.3389/fmicb.2017.02132 %0 Journal Article %J Viruses %D 2017 %T Emerging interaction patterns in the emiliania huxleyi-EhV system %A Ruiz, Eliana %A Oosterhof, Monique %A Sandaa, Ruth-Anne %A Larsen, Aud %A Pagarete, António %K algae virus %K coccolithophore %K coccolithovirus %K cost of %K haptophyta %K infectivity trade-offs %K killing-the-winner %K marine viral ecology %K phycodnaviridae %K RCC1211 %K RCC1213 %K RCC1215 %K RCC1216 %K RCC1218 %K RCC1228 %K RCC1231 %K RCC1235 %K RCC1239 %K RCC1241 %K RCC1242 %K RCC1246 %K RCC1249 %K RCC1250 %K RCC1253 %K RCC1255 %K rcc1256 %K RCC1257 %K RCC1259 %K RCC1268 %K RCC1269 %K RCC1272 %K RCC1276 %K RCC1322 %K RCC1744 %K RCC1745 %K RCC1857 %K RCC3548 %K RCC3856 %K RCC3923 %K RCC3956 %K resistance %K viral-host interactions %X Viruses are thought to be fundamental in driving microbial diversity in the oceanic planktonic realm. That role and associated emerging infection patterns remain particularly elusive for eukaryotic phytoplankton and their viruses. Here we used a vast number of strains from the model system Emiliania huxleyi/Emiliania huxleyi Virus to quantify parameters such as growth rate (µ), resistance (R), and viral production (Vp) capacities. Algal and viral abundances were monitored by flow cytometry during 72-h incubation experiments. The results pointed out higher viral production capacity in generalist EhV strains, and the virus-host infection network showed a strong co-evolution pattern between E. huxleyi and EhV populations. The existence of a trade-off between resistance and growth capacities was not confirme %B Viruses %V 9 %P 61 %8 mar %G eng %U http://www.mdpi.com/1999-4915/9/3/61 %R 10.3390/v9030061 %0 Journal Article %J Plant Physiology %D 2017 %T Glycerolipid characterization and nutrient deprivation-associated changes in the green picoalga ostreococcus tauri %A Degraeve-Guilbault, Charlotte %A Bréhélin, Claire %A Haslam, Richard %A Sayanova, Olga %A Marie-Luce, Glawdys %A Jouhet, Juliette %A Corellou, Florence %K rcc3401 %K RCC4222 %K RCC745 %K RCC788 %K RCC789 %K RCC802 %K RCC809 %K RCC834 %X The picoalga Ostreococcus tauri is a minimal photosynthetic eukaryote that has been used as a model system. O. tauri is known to efficiently produce docosahexaenoic acid (DHA). We provide a comprehensive study of the glycerolipidome of O. tauri and validate this species as model for related picoeukaryotes. O. tauri lipids displayed unique features that combined traits from the green and the chromalveolate lineages. The betaine lipid diacylglyceryl-hydroxymethyl-trimethyl-β-alanine and phosphatidyldimethylpropanethiol, both hallmarks of chromalveolates, were identified as presumed extraplastidial lipids. DHA was confined to these lipids, while plastidial lipids of prokaryotic type were characterized by the overwhelming presence of ω-3 C18 polyunsaturated fatty acids (FAs), 18:5 being restricted to galactolipids. C16:4, an FA typical of green microalgae galactolipids, also was a major component of O. tauri extraplastidial lipids, while the 16:4-coenzyme A (CoA) species was not detected. Triacylglycerols (TAGs) displayed the complete panel of FAs, and many species exhibited combinations of FAs diagnostic for plastidial and extraplastidial lipids. Importantly, under nutrient deprivation, 16:4 and ω-3 C18 polyunsaturated FAs accumulated into de novo synthesized TAGs while DHA-TAG species remained rather stable, indicating an increased contribution of FAs of plastidial origin to TAG synthesis. Nutrient deprivation further severely down-regulated the conversion of 18:3 to 18:4, resulting in obvious inversion of the 18:3/18:4 ratio in plastidial lipids, TAGs, as well as acyl-CoAs. The fine-tuned and dynamic regulation of the 18:3/18:4 ratio suggested an important physiological role of these FAs in photosynthetic membranes. Acyl position in structural and storage lipids together with acyl-CoA analysis further help to determine mechanisms possibly involved in glycerolipid synthesis. %B Plant Physiology %V 173 %P 2060–2080 %G eng %U http://www.plantphysiol.org/lookup/doi/10.1104/pp.16.01467 %R 10.1104/pp.16.01467 %0 Journal Article %J Proceedings of the National Academy of Sciences %D 2017 %T Host-derived viral transporter protein for nitrogen uptake in infected marine phytoplankton %A Monier, Adam %A Chambouvet, Aurelie %A Milner, David S. %A Attah, Victoria %A Terrado, Ramón %A Lovejoy, Connie %A Moreau, Hervé %A Santoro, Alyson E. %A Derelle, Evelyne %A Richards, Thomas A. %K rcc1107 %K RCC1621 %K RCC2573 %K RCC2593 %K RCC745 %K RCC809 %B Proceedings of the National Academy of Sciences %P 201708097 %G eng %U http://www.pnas.org/lookup/doi/10.1073/pnas.1708097114 %R 10.1073/pnas.1708097114 %0 Journal Article %J Harmful Algae %D 2017 %T Mixotrophy in the marine red-tide cryptophyte Teleaulax amphioxeia and ingestion and grazing impact of cryptophytes on natural populations of bacteria in Korean coastal waters %A Yoo, Yeong Du %A Seong, Kyeong Ah %A Jeong, Hae Jin %A Yih, Wonho %A Rho, Jung Rae %A Nam, Seung Won %A Kim, Hyung Seop %K Bloom %K Flagellate %K Grazing impact %K Predator-prey relationship %K RCC1086 %K Red tide %X Cryptophytes are ubiquitous and one of the major phototrophic components in marine plankton communities. They often cause red tides in the waters of many countries. Understanding the bloom dynamics of cryptophytes is, therefore, of great importance. A critical step in this understanding is unveiling their trophic modes. Prior to this study, several freshwater cryptophyte species and marine Cryptomonas sp. and Geminifera cryophila were revealed to be mixotrophic. The trophic mode of the common marine cryptophyte species, Teleaulax amphioxeia has not been investigated yet. Thus, to explore the mixotrophic ability of T. amphioxeia by assessing the types of prey species that this species is able to feed on, the protoplasms of T. amphioxeia cells were carefully examined under an epifluorescence microscope and a transmission electron microscope after adding each of the diverse prey species. Furthermore, T. amphioxeia ingestion rates heterotrophic bacteria and the cyanobacterium Synechococcus sp. were measured as a function of prey concentration. Moreover, the feeding of natural populations of cryptophytes on natural populations of heterotrophic bacteria was assessed in Masan Bay in April 2006. This study reported for the first time, to our knowledge, that T. amphioxeia is a mixotrophic species. Among the prey organisms offered, T. amphioxeia fed only on heterotrophic bacteria and Synechococcus sp. The ingestion rates of T. amphioxeia on heterotrophic bacteria or Synechococcus sp. rapidly increased with increasing prey concentrations up to 8.6 × 106 cells ml-1, but slowly at higher prey concentrations. The maximum ingestion rates of T. amphioxeia on heterotrophic bacteria and Synechococcus sp. reached 0.7 and 0.3 cells predator-1 h-1, respectively. During the field experiments, the ingestion rates and grazing coefficients of cryptophytes on natural populations of heterotrophic bacteria were 0.3–8.3 cells predator-1 h-1 and 0.012–0.033 d-1, respectively. Marine cryptophytes, including T. amphioxeia, are known to be favorite prey species for many mixotrophic and heterotrophic dinoflagellates and ciliates. Cryptophytes, therefore, likely play important roles in marine food webs and may exert a considerable potential grazing impact on the populations of marine bacteria. %B Harmful Algae %V 68 %P 105–117 %G eng %U http://dx.doi.org/10.1016/j.hal.2017.07.012 %R 10.1016/j.hal.2017.07.012 %0 Journal Article %J Journal of Phycology %D 2017 %T Morphological and genetic diversity of Beaufort Sea diatoms with high contributions from the Chaetoceros neogracilis species complex %A Balzano, Sergio %A Percopo, Isabella %A Siano, Raffaele %A Gourvil, Priscillia %A Chanoine, Mélanie %A Marie, Dominique %A Vaulot, Daniel %A Sarno, Diana %E Wood, M. %K RCC1984 %K RCC1985 %K RCC1986 %K RCC1988 %K RCC1989 %K RCC1990 %K RCC1991 %K RCC1992 %K RCC1993 %K RCC1995 %K RCC1997 %K RCC1999 %K RCC2000 %K RCC2002 %K RCC2003 %K RCC2004 %K RCC2005 %K RCC2006 %K RCC2008 %K RCC2010 %K RCC2011 %K RCC2012 %K RCC2014 %K RCC2016 %K RCC2017 %K RCC2021 %K RCC2037 %K RCC2038 %K RCC2039 %K RCC2042 %K RCC2043 %K RCC2261 %K RCC2262 %K RCC2263 %K RCC2264 %K RCC2265 %K RCC2266 %K RCC2267 %K RCC2268 %K RCC2269 %K RCC2270 %K RCC2272 %K RCC2273 %K RCC2274 %K RCC2275 %K RCC2276 %K RCC2277 %K RCC2278 %K RCC2279 %K RCC2280 %K RCC2281 %K RCC2282 %K RCC2318 %K RCC2506 %K RCC2517 %K RCC2520 %K RCC2521 %K RCC2522 %X Seventy-five diatom strains isolated from the Beaufort Sea (Canadian Arctic) in the summer of 2009 were characterized by light and electron microscopy (SEM and TEM), as well as 18S and 28S rRNA gene sequencing. These strains group into 20 genotypes and 17 morphotypes and are affiliated with the genera Arcocellulus, Attheya, Chaetoceros, Cylindrotheca, Eucampia, Nitzschia, Porosira, Pseudo-nitzschia, Shionodiscus, Thalassiosira, and Synedropsis. Most of the species have a distribution confined to the northern/polar area. Chaetoceros neogracilis and Chaetoceros gelidus were the most represented taxa. Strains of C. neogracilis were morphologically similar and shared identical 18S rRNA gene sequences, but belonged to four distinct genetic clades based on 28S rRNA, ITS-1 and ITS-2 phylogenies. Secondary structure prediction revealed that these four clades differ in hemi-compensatory base changes (HCBCs) in paired positions of the ITS-2, suggesting their inability to interbreed. Reproductively isolated C. neogracilis genotypes can thus co-occur in summer phytoplankton communities in the Beaufort Sea. C. neogracilis generally occurred as single cells but also formed short colonies. It is phylogenetically distinct from an Antarctic species, erroneously identified in some previous studies as C. neogracilis, but named here as Chaetoceros sp. This work provides taxonomically validated sequences for 20 Arctic diatom taxa, which will facilitate future metabarcoding studies on phytoplankton in this region. %B Journal of Phycology %V 53 %P 161–187 %8 feb %G eng %U http://doi.wiley.com/10.1111/jpy.12489 %R 10.1111/jpy.12489 %0 Journal Article %J Environmental Microbiology %D 2017 %T Occurrence of chlorophyll allomers during virus-induced mortality and population decline in the ubiquitous picoeukaryote Ostreococcus tauri %A Steele, Deborah J. %A Kimmance, Susan A. %A Franklin, Daniel J. %A Airs, Ruth L. %K biodegradation %K crude oil %K eukaryotic phytoplankton %K hydrocarbon-degrading bacteria (HCB) %K marine environment %K micro- algae %K RCC745 %X Phytoplankton have been shown to harbour a diversity of hydrocarbonoclastic bacteria (HCB), yet it is not understood how these phytoplankton-associated HCB would respond in the event of an oil spill at sea. Here, we assess the diversity and dynamics of the bacterial community associated with a natural population of marine phytoplankton under oil spill-simulated conditions, and compare it to that of the free-living (non phytoplankton-associated) bacterial community. Whilst the crude oil severely impacted the phytoplankton population and was likely conducive to marine oil snow (MOS) formation, analysis of the MiSeq-derived 16S rRNA data revealed dramatic and differential shifts in the oil-amended communities that included blooms of recognised HCB (e.g. Thalassospira, Cycloclasticus), including putative novel phyla, as well as other groups with previously unqualified oil-degrading potential (Olleya, Winogradskyella, and members of the inconspicuous BD7-3 phylum). Notably, the oil biodegradation potential of the phytoplankton-associated community exceeded that of the free-living community, and it showed a preference to degrade substituted and non-substituted polycyclic aromatic hydrocarbons. Our study provides evidence of compartmentalisation of hydrocarbon-degrading capacity in the marine water column, wherein HCB associated with phytoplankton are better tuned to degrading crude oil hydrocarbons than that by the community of planktonic free-living bacteria. %B Environmental Microbiology %V in press %P 1–41 %8 nov %G eng %U http://doi.wiley.com/10.1111/1462-2920.13980 %R 10.1111/1462-2920.13980 %0 Journal Article %J Physiologia Plantarum %D 2017 %T Photoinhibition in marine picocyanobacteria %A Soitamo, Arto %A Havurinne, Vesa %A Tyystjärvi, Esa %K RCC156 %K RCC2366 %K rcc296 %K RCC407 %X Marine Synechococcus and Prochlorococcus cyanobacteria have different antenna compositions although they are genetically near to each other, and different strains thrive in very different illumination conditions. We measured growth and photoinhibition of PSII in two low-light and one high-light Prochlorococcus strains and in one Synechococcus strain. All strains were found to be able to shortly utilize moderate or even high light, but the low-light strains bleached rapidly in moderate light. Measurements of photoinhibition in the presence of the antibiotic lincomycin showed that a low-light Prochlorococcus strain was more sensitive than a high-light strain and both were more sensitive than the marine Synechococcus. The action spectrum of photoinhibition showed an increase from blue to ultraviolet wavelengths in all strains, suggesting contribution of manganese absorption to photoinhibition, but blue light caused less photoinhibition in marine cyanobacteria than expected on the basis of earlier results from plants and cyanobacteria. The visible-light part of the action spectrum resembled the absorption spectrum of the organism, suggesting that photosynthetic antenna pigments, especially divinyl chlorophylls, have a more important role as photoreceptors of visible-light photoinhibition in marine cyanobacteria than in other photoautotrophs. %B Physiologia Plantarum %V 161 %P 97–108 %8 sep %G eng %U https://doi.org/10.1111/ppl.12571 %R 10.1111/ppl.12571 %0 Journal Article %J Environmental Microbiology %D 2017 %T Physiological and proteomic characterization of light adaptations in marine Synechococcus %A Mackey, Katherine R. M. %A Post, Anton F %A McIlvin, Matthew R %A Saito, Mak A %K rcc539 %K rcc752 %B Environmental Microbiology %V 19 %P 2348–2365 %8 jun %G eng %U http://doi.wiley.com/10.1111/1462-2920.13744 %R 10.1111/1462-2920.13744 %0 Journal Article %J Science Advances %D 2017 %T Population genomics of picophytoplankton unveils novel chromosome hypervariability %A Blanc-Mathieu, Romain %A Krasovec, Marc %A Hebrard, Maxime %A Yau, Sheree %A Desgranges, Elodie %A Martin, Joel %A Schackwitz, Wendy %A Kuo, Alan %A Salin, Gerald %A Donnadieu, Cecile %A Desdevises, Yves %A Sanchez-Ferandin, Sophie %A Moreau, Hervé %A Rivals, Eric %A Grigoriev, Igor V. %A Grimsley, Nigel %A Eyre-Walker, Adam %A Piganeau, Gwenael %K RCC1105 %K RCC1108 %K RCC1110 %K RCC1112 %K RCC1114 %K RCC1115 %K RCC1116 %K RCC1117 %K RCC1118 %K RCC1123 %K RCC1558 %K RCC1559 %K RCC1561 %K RCC299 %K RCC4221 %K RCC809 %B Science Advances %V 3 %P e1700239 %8 jul %G eng %U http://advances.sciencemag.org/lookup/doi/10.1126/sciadv.1700239 %R 10.1126/sciadv.1700239 %0 Journal Article %J Environmental Microbiology %D 2017 %T Quantitative biogeography of picoprasinophytes establishes ecotype distributions and significant contributions to marine phytoplankton %A Limardo, Alexander J. %A Sudek, Sebastian %A Choi, Chang Jae %A Poirier, Camille %A Rii, Yoshimi M. %A Blum, Marguerite %A Roth, Robyn %A Goodenough, Ursula %A Church, Matthew J. %A Worden, Alexandra Z. %K RCC1105 %K RCC715 %K RCC716 %K RCC809 %B Environmental Microbiology %8 jun %G eng %U http://doi.wiley.com/10.1111/1462-2920.13812 %R 10.1111/1462-2920.13812 %0 Journal Article %J Limnology and Oceanography: Methods %D 2017 %T Recommendations for obtaining unbiased chlorophyll estimates from in situ chlorophyll fluorometers: A global analysis of WET Labs ECO sensors %A Roesler, Collin %A Uitz, Julia %A Claustre, Hervé %A Boss, Emmanuel %A Xing, Xiaogang %A Organelli, Emanuele %A Briggs, Nathan %A Bricaud, Annick %A Schmechtig, Catherine %A Poteau, Antoine %A D'Ortenzio, Fabrizio %A Ras, Josephine %A Drapeau, Susan %A Haëntjens, Nils %A Barbieux, Marie %K RCC233 %K RCC42 %K RCC834 %X Chlorophyll fluorometers provide the largest in situ global data set for estimating phytoplankton biomass because of their ease of use, size, power consumption, and relatively low price. While in situ chlorophyll a (Chl) fluorescence is proxy for Chl a concentration, and hence phytoplankton biomass, there exist large natural variations in the relationship between in situ fluorescence and extracted Chl a concentration. Despite this large natural variability, we present here a global validation data set for the WET Labs Environmental Characterization Optics (ECO) series chlorophyll fluorometers that suggests a factor of 2 overestimation in the factory calibrated Chl a estimates for this specific manufacturer and series of sensors. We base these results on paired High Pressure Liquid Chromatography (HPLC) and in situ fluorescence match ups for which non-photochemically quenched fluorescence observations were removed. Additionally, we examined matchups between the factory-calibrated in situ fluorescence and estimates of chlorophyll concentration determined from in situ radiometry, absorption line height, NASA's standard ocean color algorithm as well as laboratory calibrations with phytoplankton monocultures spanning diverse species that support the factor of 2 bias. We therefore recommend the factor of 2 global bias correction be applied for the WET Labs ECO sensors, at the user level, to improve the global accuracy of chlorophyll concentration estimates and products derived from them. We recommend that other fluorometer makes and models should likewise undergo global analyses to identify potential bias in factory calibration. %B Limnology and Oceanography: Methods %V 15 %P 572–585 %G eng %R 10.1002/lom3.10185 %0 Journal Article %J Bulletin of Environmental Contamination and Toxicology %D 2017 %T Removal and biodegradation of phenanthrene, fluoranthene and pyrene by the marine algae rhodomonas baltica enriched from north atlantic coasts %A Arias, Andrés H %A Souissi, Anissa %A Glippa, Olivier %A Roussin, Marion %A Dumoulin, David %A Net, Sopheak %A Ouddane, Baghdad %A Souissi, Sami %K RCC350 %X This study is focused on the removal, accumulation and degradation of three environmental ubiquitous polycyclic aromatic hydrocarbons (PAHs), phenanthrene (PHE), fluoranthene (FLA) and pyrene (PYR), by the marine alga Rhodomonas baltica enriched from the English Channel. After separation, purification and culture in several phases, R. baltica was exposed to PAH concentrations that are frequently encountered in the field in several anthropized environments. The results showed that R. baltica can grow under PAH stress, efficiently remove up to 70% of these compounds from the medium by 216 h of culture and selectively bioaccumulate PAHs by their hydrophobicity. Between PHE, FLA and PYR, phenanthrene was the compound with higher degradation rates throughout incubation. The equilibrium partitioning theoretical approach showed that physico-chemical partitioning, rather than active bioconcentration, was the major factor governing the bioaccumulation, outlying a potential application in decontamination processes for this species. %B Bulletin of Environmental Contamination and Toxicology %V 98 %P 392–399 %G eng %U https://doi.org/10.1007/s00128-016-1967-4 %R 10.1007/s00128-016-1967-4 %0 Journal Article %J Protist %D 2017 %T Revision of the genus micromonas manton et parke (chlorophyta, mamiellophyceae), of the type species m. pusilla (butcher) manton & parke and of the species m. commoda van baren, bachy and worden and description of two new species based on the genetic %A Simon, Nathalie %A Foulon, Elodie %A Grulois, Daphne %A Six, Christophe %A Desdevises, Yves %A Latimier, Marie %A Le Gall, Florence %A Tragin, Margot %A Houdan, Aude %A Derelle, Evelyne %A Jouenne, Fabien %A Marie, Dominique %A Le Panse, Sophie %A Vaulot, Daniel %A Marin, Birger %K 2017 %K ASSEMBLE %K rcc %K RCC1109 %K RCC114 %K RCC2306 %K RCC2308 %K RCC299 %K RCC372 %K RCC373 %K RCC418 %K RCC434 %K RCC447 %K RCC448 %K RCC449 %K RCC450 %K RCC451 %K RCC461 %K RCC465 %K RCC472 %K RCC497 %K RCC498 %K RCC570 %K RCC629 %K RCC647 %K RCC658 %K RCC676 %K RCC692 %K RCC746 %K RCC803 %K RCC804 %K RCC805 %K RCC806 %K RCC807 %K RCC808 %K RCC828 %K RCC829 %K RCC830 %K RCC831 %K RCC833 %K RCC834 %K RCC835 %K RCC836 %K SBR$_\textrmP$hyto$_\textrmD$IPO %K SBR$_\textrmP$hyto$_\textrmP$PM %K sbr?hyto$_\textrmd$ipo %B Protist %V 168 %P 612–635 %8 nov %G eng %U http://linkinghub.elsevier.com/retrieve/pii/S1434461017300780 %R 10.1016/j.protis.2017.09.002 %0 Journal Article %J The ISME Journal %D 2017 %T Temperature is a key factor in Micromonas–virus interactions %A Demory, David %A Arsenieff, Laure %A Simon, Nathalie %A Six, Christophe %A Rigaut-jalabert, Fabienne %A Marie, Dominique %A Ge, Pei %A Bigeard, Estelle %A Jacquet, Stéphan %A Sciandra, Antoine %A Bernard, Olivier %A Rabouille, Sophie %A Baudoux, Anne-claire %K 2017 %K RCC4229 %K RCC4253 %K RCC4265 %K RCC451 %K RCC829 %K RCC834 %K sbr?hyto$_\textrmd$ipo %K sbr?hyto?app %X The genus Micromonas comprises phytoplankton that show among the widest latitudinal distributions on Earth, and members of this genus are recurrently infected by prasinoviruses in contrasted thermal ecosystems. In this study, we assessed how temperature influences the interplay between the main genetic clades of this prominent microalga and their viruses. The growth of three Micromonas strains (Mic-A, Mic-B, Mic-C) and the stability of their respective lytic viruses (MicV-A, MicV-B, MicV-C) were measured over a thermal range of 4–32.5 °C. Similar growth temperature optima (Topt) were predicted for all three hosts but Mic-B exhibited a broader thermal tolerance than Mic-A and Mic-C, suggesting distinct thermoacclimation strategies. Similarly, the MicV-C virus displayed a remarkable thermal stability compared with MicV-A and MicV-B. Despite these divergences, infection dynamics showed that temperatures below Topt lengthened lytic cycle kinetics and reduced viral yield and, notably, that infection at temperatures above Topt did not usually result in cell lysis. Two mechanisms operated depending on the temperature and the biological system. Hosts either prevented the production of viral progeny or maintained their ability to produce virions with no apparent cell lysis, pointing to a possible switch in the viral life strategy. Hence, temperature changes critically affect the outcome of Micromonas infection and have implications for ocean biogeochemistry and evolution. %B The ISME Journal %V 11 %P 601–612 %8 mar %G eng %U http://dx.doi.org/10.1038/ismej.2016.160 http://www.nature.com/doifinder/10.1038/ismej.2016.160 %R 10.1038/ismej.2016.160 %0 Journal Article %J The ISME Journal %D 2017 %T Use of plankton-derived vitamin B1 precursors, especially thiazole-related precursor, by key marine picoeukaryotic phytoplankton %A Paerl, Ryan W %A Bouget, François-Yves %A Lozano, Jean-Claude %A Vergé, Valérie %A Schatt, Philippe %A Allen, Eric E %A Palenik, Brian %A Azam, Farooq %K rcc3401 %K RCC745 %B The ISME Journal %V 11 %P 753–765 %8 mar %G eng %U http://www.nature.com/doifinder/10.1038/ismej.2016.145 %R 10.1038/ismej.2016.145 %0 Journal Article %J Applied and Environmental Microbiology %D 2016 %T Abundance and biogeography of picoprasinophyte ecotypes and other phytoplankton in the eastern north pacific ocean %A Simmons, Melinda P. %A Sudek, Sebastian %A Monier, Adam %A Limardo, Alexander J. %A Jimenez, Valeria %A Perle, Christopher R. %A Elrod, Virginia A. %A Pennington, J. Timothy %A Worden, Alexandra Z. %E Schloss, P. D. %K 2016 %K rcc %X Eukaryotic algae within the picoplankton size class (<=2 ??m in diameter) are important marine primary producers, but their spatial and ecological distributions are not well characterized. Here, we studied three picoeukaryotic prasinophyte genera and their cyanobacterial counterparts, Prochlorococcus and Synechococcus , during two cruises along a North Pacific transect characterized by different ecological regimes. Picoeukaryotes and Synechococcus reached maximum abundances of 1.44 × 10 5 and 3.37 × 10 5 cells ? ml -1 , respectively, in mesotrophic waters, while Prochlorococcus reached 1.95 × 10 5 cells ? ml -1 in the oligotrophic ocean. Of the picoeukaryotes, Bathycoccus was present at all stations in both cruises, reaching 21,368 ± 327 18S rRNA gene copies ? ml -1 . Micromonas and Ostreococcus clade OI were detected only in mesotrophic and coastal waters and Ostreococcus clade OII only in the oligotrophic ocean. To resolve proposed Bathycoccus ecotypes, we established genetic distances for 1,104 marker genes using targeted metagenomes and the Bathycoccus prasinos genome. The analysis was anchored in comparative genome analysis of three Ostreococcus species for which physiological and environmental data are available to facilitate data interpretation. We established that two Bathycoccus ecotypes exist, named here BI (represented by coastal isolate Bathycoccus prasinos ) and BII. These share 82% ± 6% nucleotide identity across homologs, while the Ostreococcus spp. share 75% ± 8%. We developed and applied an analysis of ecomarkers to metatranscriptomes sequenced here and published -omics data from the same region. The results indicated that the Bathycoccus ecotypes cooccur more often than Ostreococcus clades OI and OII do. Exploratory analyses of relative transcript abundances suggest that Bathycoccus NRT2.1 and AMT2.2 are high-affinity NO 3 - and low-affinity NH 4 + transporters, respectively, with close homologs in multiple picoprasinophytes. Additionally, in the open ocean, where dissolved iron concentrations were low (0.08 nM), there appeared to be a shift to the use of nickel superoxide dismutases (SODs) from Mn/Fe/Cu SODs closer inshore. Our study documents the distribution of picophytoplankton along a North Pacific ecological gradient and offers new concepts and techniques for investigating their biogeography. %B Applied and Environmental Microbiology %V 82 %P 1693–1705 %8 mar %G eng %U http://aem.asm.org/lookup/doi/10.1128/AEM.02730-15 %R 10.1128/AEM.02730-15 %0 Journal Article %J Nature Communications %D 2016 %T Decrease in coccolithophore calcification and CO2 since the middle Miocene %A Bolton, Clara T. %A Hernández-Sánchez, María T. %A Fuertes, Miguel-Ángel %A González-Lemos, Saúl %A Abrevaya, Lorena %A Méndez-Vicente, Ana %A Flores, José-Abel %A Probert, Ian %A Giosan, Liviu %A Johnson, Joel %A Stoll, Heather M. %K 2016 %K rcc %X Marine algae are instrumental in carbon cycling and atmospheric carbon dioxide (CO2) regulation. One group, coccolithophores, uses carbon to photosynthesize and to calcify, covering their cells with chalk platelets (coccoliths). How ocean acidification influences coccolithophore calcification is strongly debated, and the effects of carbonate chemistry changes in the geological past are poorly understood. This paper relates degree of coccolith calcification to cellular calcification, and presents the first records of size-normalized coccolith thickness spanning the last 14 Myr from tropical oceans. Degree of calcification was highest in the low-pH, high-CO2 Miocene ocean, but decreased significantly between 6 and 4 Myr ago. Based on this and concurrent trends in a new alkenone ep record, we propose that decreasing CO2 partly drove the observed trend via reduced cellular bicarbonate allocation to calcification. This trend reversed in the late Pleistocene despite low CO2, suggesting an additional regulator of calcification such as alkalinity. 1 %B Nature Communications %V 7 %P 10284 %G eng %U http://www.nature.com/doifinder/10.1038/ncomms10284 %R 10.1038/ncomms10284 %0 Journal Article %J The ISME Journal %D 2016 %T Diversity and oceanic distribution of Parmales (Bolidophyceae), a picoplankton group closely related to diatoms %A Ichinomiya, Mutsuo %A Lopes dos Santos, A %A Gourvil, Priscillia %A Yoshikawa, Shinya %A Kamiya, Mitsunobu %A Ohki, Kaori %A Audic, S %A de Vargas, Colomban %A Vaulot, Daniel %A Kuwata, Akira %K 2016 %K MACUMBA %K MicroB3 %K rcc %K SBR$_\textrmP$hyto$_\textrmD$PO %K sbr?hyto$_\textrmd$ipo %K sbr?hyto?ppo %B The ISME Journal %V in press %G eng %R 10.1038/ismej.2016.38 %0 Journal Article %J FEMS Microbiology Ecology %D 2016 %T Historical records from dated sediment cores reveal the multidecadal dynamic of the toxic dinoflagellate Alexandrium minutum in the Bay of Brest (France) %A Klouch, Khadidja Z %A Schmidt, Sabine %A Andrieux-Loyer, Françoise %A Le Gac, Mickaël %A Hervio-Heath, Dominique %A Qui-Minet, Zujaila N %A Quéré, Julien %A Bigeard, Estelle %A Guillou, Laure %A Siano, Raffaele %E Laanbroek, Riks %K 2016 %K rcc %K sbr?hyto$_\textrmd$ipo %X The multiannual dynamic of the cyst-forming and toxic marine dinoflagellate Alexandrium minutum was studied over a time scale of about 150 years by a paleoecological approach based on ancient DNA (aDNA) quantification and cyst revivification data obtained from two dated sediment cores of the Bay of Brest (Brittany, France). The first genetic traces of the species presence in the study area dated back to 1873 ± 6. Specific aDNA could be quantified by a newly-developed real-time PCR assay in the upper core layers, in which the germination of the species (in up to 17-19 year-old sediments) was also obtained. In both cores studied, our quantitative paleogenetic data showed a statistically significant increasing trend in the abundance of A. minutum ITS1 rDNA copies over time, corroborating three decades of local plankton data that have documented an increasing trend in the species cell abundance. By comparison, paleogenetic data of the dinoflagellate Scrippsiella donghaienis did not show a coherent trend between the cores studied, supporting the hypothesis of the existence of a species-specific dynamic of A. minutum in the study area. This work contributes to the development of paleoecological research, further showing its potential for biogeographical, ecological and evolutionary studies on marine microbes. %B FEMS Microbiology Ecology %V 92 %P fiw101 %8 jul %G eng %U http://www.ncbi.nlm.nih.gov/pubmed/27162179 https://academic.oup.com/femsec/article-lookup/doi/10.1093/femsec/fiw101 %R 10.1093/femsec/fiw101 %0 Journal Article %J PloS one %D 2016 %T Identifying aspects of the post-transcriptional program governing the proteome of the green alga micromonas pusilla. %A Waltman, Peter H %A Guo, Jian %A Reistetter, Emily Nahas %A Purvine, Samuel %A Ansong, Charles K %A van Baren, Marijke J %A Wong, Chee-Hong %A Wei, Chia-Lin %A Smith, Richard D %A Callister, Stephen J %A Stuart, Joshua M %A Worden, Alexandra Z %K 2016 %K rcc %K RCC834 %X Micromonas is a unicellular motile alga within the Prasinophyceae, a green algal group that is related to land plants. This picoeukaryote (¡2 ??m diameter) is widespread in the marine environment but is not well understood at the cellular level. Here, we examine shifts in mRNA and protein expression over the course of the day-night cycle using triplicated mid-exponential, nutrient replete cultures of Micromonas pusilla CCMP1545. Samples were collected at key transition points during the diel cycle for evaluation using high-throughput LC-MS proteomics. In conjunction, matched mRNA samples from the same time points were sequenced using pair-ended directional Illumina RNA-Seq to investigate the dynamics and relationship between the mRNA and protein expression programs of M. pusilla. Similar to a prior study of the marine cyanobacterium Prochlorococcus, we found significant divergence in the mRNA and proteomics expression dynamics in response to the light:dark cycle. Additionally, expressional responses of genes and the proteins they encoded could also be variable within the same metabolic pathway, such as we observed in the oxygenic photosynthesis pathway. A regression framework was used to predict protein levels from both mRNA expression and gene-specific sequence-based features. Several features in the genome sequence were found to influence protein abundance including codon usage as well as 3' UTR length and structure. Collectively, our studies provide insights into the regulation of the proteome over a diel cycle as well as the relationships between transcriptional and translational programs in the widespread marine green alga Micromonas. %B PloS one %V 11 %P e0155839 %8 jan %G eng %U http://dx.doi.org/10.1371/journal.pone.0155839 %R 10.1371/journal.pone.0155839 %0 Journal Article %J Phycologia %D 2016 %T New insights into the morphology and phylogeny of Heterosigma akashiwo (Raphidophyceae), with the description of Heterosigma minor sp. nov . %A Engesmo, Anette %A Eikrem, Wenche %A Seoane, Sergio %A Smith, Kirsty %A Edvardsen, Bente %A Hofgaard, Antje %A Tomas, Carmelo R. %K 2016 %K rcc1501 %K rcc1502 %B Phycologia %V 55 %P 279–294 %8 may %G eng %U http://www.phycologia.org/doi/10.2216/15-115.1 %R 10.2216/15-115.1 %0 Journal Article %J PloS one %D 2016 %T Phenotypic variability in the coccolithophore emiliania huxleyi. %A Blanco-Ameijeiras, Sonia %A Lebrato, Mario %A Stoll, Heather M %A Iglesias-Rodriguez, Debora %A Müller, Marius N %A Méndez-Vicente, Ana %A Oschlies, Andreas %K 2016 %K rcc1212 %K RCC1215 %K RCC1216 %K RCC1228 %K rcc1238 %K RCC1255 %K rcc1258 %K RCC1259 %K rcc1731 %K rcc3553 %X Coccolithophores are a vital part of oceanic phytoplankton assemblages that produce organic matter and calcium carbonate (CaCO3) containing traces of other elements (i.e. Sr and Mg). Their associated carbon export from the euphotic zone to the oceans' interior plays a crucial role in CO2 feedback mechanisms and biogeochemical cycles. The coccolithophore Emiliania huxleyi has been widely studied as a model organism to understand physiological, biogeochemical, and ecological processes in marine sciences. Here, we show the inter-strain variability in physiological and biogeochemical traits in 13 strains of E. huxleyi from various biogeographical provinces obtained from culture collections commonly used in the literature. Our results demonstrate that inter-strain genetic variability has greater potential to induce larger phenotypic differences than the phenotypic plasticity of single strains cultured under a broad range of variable environmental conditions. The range of variation found in physiological parameters and calcite Sr:Ca highlights the need to reconsider phenotypic variability in paleoproxy calibrations and model parameterizations to adequately translate findings from single strain laboratory experiments to the real ocean. %B PloS one %V 11 %P e0157697 %8 jan %G eng %U http://dx.doi.org/10.1371/journal.pone.0157697 %R 10.1371/journal.pone.0157697 %0 Journal Article %J Journal of Phycology %D 2016 %T Photosynthetic pigments of oceanic Chlorophyta belonging to prasinophytes clade VII %A Lopes dos Santos, Adriana %A Gourvil, Priscillia %A Rodriguez-Hernandez, Francisco %A Garrido, José Luis %A Vaulot, Daniel %K 2016 %K MACUMBA %K rcc %K RCC1124 %K RCC15 %K RCC1871 %K RCC2337 %K RCC2339 %K RCC287 %K RCC3374 %K RCC3376 %K RCC3402 %K RCC719 %K RCC856 %K RCC857 %K RCC996 %K RCC998 %K RCC?o?dd %K SBR$_\textrmP$hyto$_\textrmD$IPO %K sbr?hyto$_\textrmd$ipo %X The ecological importance and diversity of pico/ nanoplanktonic algae remains poorly studied in marine waters, in part because many are tiny and without distinctive morphological features. Amongst green algae, Mamiellophyceae such as Micromonas or Bathycoccus are dominant in coastal waters while prasinophytes clade VII, yet not formerly described, appear to be major players in open oceanic waters. The pigment composition of 14 strains representative of different subclades of clade VII was analyzed using a method that improves the separation of loroxanthin and neoxanthin. All the prasinophytes clade VII analyzed here showed a pigment composition similar to that previously reported for RCC287 corresponding to pigment group prasino-2A. However, we detected in addition astaxanthin for which it is the first report in prasinophytes. Among the strains analyzed, the pigment signature is qualitatively similar within subclades A and B. By contrast, RCC3402 from subclade C (Picocystis) lacks loroxanthin, astaxanthin, and antheraxanthin but contains alloxanthin, diatoxanthin, and monadoxanthin that are usually found in diatoms or cryptophytes. For subclades A and B, loroxanthin was lowest at highest light irradiance suggesting a light-harvesting role of this pigment in clade VII as in Tetraselmis. %B Journal of Phycology %V 52 %P 148–155 %G eng %R 10.1111/jpy.12376 %0 Journal Article %J Perspectives in Phycology %D 2016 %T Phylogenetic diversity and ecology of green micro algae in marine systems %A Tragin, M %A Lopes dos Santos, Adriana %A Christen, R. %A Vaulot, D. %K 2016 %K ? No DOI found %K rcc %K sbr?hyto$_\textrmd$ipo %B Perspectives in Phycology %V in press %G eng %0 Journal Article %J Fronitiers in Marine Science %D 2016 %T The physiological response of picophytoplankton to temperature and its model representation %A Stawiarski, Beate %A Buitenhuis, Erik T %A Quéré, Corinne Le %K chlorophyll a to carbon %K chlorophyll a to carbon ratio %K Eppley %K frontiers in marine science %K frontiersin %K org %K physiological parameterization %K phytoplankton growth rates %K phytoplankton size scaling %K picoeukaryotes %K picophytoplankton %K ratio %K rcc162 %K rcc1677 %K rcc212 %K rcc289 %K rcc296 %K rcc30 %K rcc361 %K rcc438 %K rcc503 %K temperature tolerance %K www %B Fronitiers in Marine Science %V 3 %P 1–13 %G eng %R 10.3389/fmars.2016.00164 %0 Journal Article %J Journal of Phycology %D 2016 %T Pseudo-nitzschia arctica sp. nov., a new cold-water cryptic Pseudo-nitzschia species within the P. pseudodelicatissima complex %A Percopo, Isabella %A Ruggiero, Maria Valeria %A Balzano, Sergio %A Gourvil, Priscillia %A Lundholm, Nina %A Siano, Raffaele %A Tammilehto, Anna %A Vaulot, Daniel %A Sarno, Diana %E Mock, T. %K RCC2002 %K RCC2004 %K RCC2005 %K RCC2517 %X A new nontoxic Pseudo-nitzschia species belonging to the P. pseudodelicatissima complex, P. arctica, was isolated from different areas of the Arctic. The erection of P. arctica is mainly supported by molecular data, since the species shares identical ultrastructure with another species in the complex, P. fryxelliana, and represents a new case of crypticity within the genus. Despite their morphological similarity, the two species are not closely related in phylogenies based on LSU, ITS and rbcL. Interestingly, P. arctica is phylogenetically most closely related to P. granii and P. subcurvata, from which the species is, however, morphologically different. P. granii and P. subcurvata lack the central larger interspace which is one of the defining features of the P. pseudodelicatissima complex. The close genetic relationship between P. arctica and the two species P. granii and P. subcurvata is demonstrated by analysis of the secondary structure of ITS2 which revealed no compensatory base changes, two hemi-compensatory base changes, and two deletions in P. arctica with respect to the other two species. These findings emphasize that rates of morphological differentiation, molecular evolution and speciation are often incongruent for Pseudo-nitzschia species, resulting in a restricted phylogenetic value for taxonomic characters used to discriminate species. The description of a new cryptic species, widely distributed in the Arctic and potentially representing an endemic component of the Arctic diatom flora, reinforces the idea of the existence of noncosmopolitan Pseudo-nitzschia species and highlights the need for combined morphological and molecular analyses to assess the distributional patterns of phytoplankton species. %B Journal of Phycology %V 52 %P 184–199 %8 apr %G eng %U http://doi.wiley.com/10.1111/jpy.12395 %R 10.1111/jpy.12395 %0 Journal Article %J Nature Communications %D 2016 %T A role for diatom-like silicon transporters in calcifying coccolithophores %A Durak, Grazyna M %A Taylor, Alison R %A Probert, Ian %A de Vargas, Colomban %A Audic, Stéphane %A Schroeder, Declan C %A Brownlee, Colin %A Wheeler, Glen L %K (RCC1130 %K (RCC1456) %K 2016 %K biomineralisation %K coccolithophores %K Gephyrocapsa oceanica (RCC1303) and Scyphosphaera %K haptophytes %K RCC1130 %K RCC1303 %K RCC1453 %K RCC1456 %K RCC3432 %K silica %K TMR5 (RCC3432—Sea of Japan) and PZ241 (RCC1453—Med %X Biomineralisation by marine phytoplankton, such as the silicifying diatoms and calcifying coccolithophores, plays an important role in carbon and nutrient cycling in the oceans. Silicification and calcification are distinct cellular processes with no known common mechanisms. As a result, it is thought that coccolithophores are able to outcompete diatoms in Si-depleted waters, which can contribute to the formation of coccolithophore blooms. Here, we show that an expanded family of diatom-like silicon transporters (SITs) are present in both silicifying and calcifying haptophyte phytoplankton, including some coccolithophores of global ecological importance. We find an essential role for Si in calcification in these coccolithophores, indicating that Si uptake contributes to the very different forms of biomineralisation in diatoms and coccolithophores. However, SITs and the requirement for Si are significantly absent from the highly abundant bloom-forming coccolithophores, such as Emiliania huxleyi. These very different requirements for Si in coccolithophores are likely to have major influence on their competitive interactions with diatoms and other siliceous phytoplankton. %B Nature Communications %V 7 %P 10543 %G eng %R 10.1038/ncomms10543 %0 Journal Article %J Scientific Reports %D 2016 %T Survey of the green picoalga Bathycoccus genomes in the global ocean %A Vannier, Thomas %A Leconte, Jade %A Seeleuthner, Yoann %A Mondy, Samuel %A Pelletier, Eric %A Aury, Jean-Marc %A de Vargas, Colomban %A Sieracki, Michael %A Iudicone, Daniele %A Vaulot, Daniel %A Wincker, Patrick %A Jaillon, Olivier %K 2016 %K RCC1105 %K RCC715 %K RCC716 %K sbr?hyto$_\textrmd$ipo %K sbr?hyto?ppo %B Scientific Reports %V 6 %P 37900 %8 dec %G eng %U http://www.nature.com/articles/srep37900 %R 10.1038/srep37900 %0 Journal Article %J Scientific Reports %D 2015 %T Eco-physiological adaptation shapes the response of calcifying algae to nutrient limitation %A Šupraha, Luka %A Gerecht, Andrea C. %A Probert, Ian %A Henderiks, Jorijntje %K 2015 %K RCC1323 %K RCC1334 %B Scientific Reports %V 5 %P 16499 %G eng %U http://www.nature.com/articles/srep16499 %R 10.1038/srep16499 %0 Journal Article %J The ISME Journal %D 2015 %T Environmental stability affects phenotypic evolution in a globally distributed marine picoplankton %A Schaum, C-Elisa %A Rost, Björn %A Collins, Sinéad %K oth95 %K rcc1107 %K RCC1108 %K RCC1114 %K RCC1558 %K rcc1645 %K rcc1662 %K rcc410 %K rcc422 %K RCC434 %K rcc501 %K rcc675 %K rcc747 %K RCC789 %K RCC809 %K rcc810 %X Marine phytoplankton can evolve rapidly when confronted with aspects of climate change because of their large population sizes and fast generation times. Despite this, the importance of environment fluctuations, a key feature of climate change, has received little attention—selection experiments with marine phytoplankton are usually carried out in stable environments and use single or few representatives of a species, genus or functional group. Here we investigate whether and by how much environmental fluctuations contribute to changes in ecologically important phytoplankton traits such as C:N ratios and cell size, and test the variability of changes in these traits within the globally distributed species Ostreococcus. We have evolved 16 physiologically distinct lineages of Ostreococcus at stable high CO2 (1031±87 ??atm CO2 , SH) and fluctuating high CO2 (1012±244 ??atm CO2 , FH) for 400 generations.We find that although both fluctuation and high CO2 drive evolution, FH- evolved lineages are smaller, have reduced C:N ratios and respond more strongly to further increases in CO2 than do SH-evolved lineages. This indicates that environmental fluctuations are an important factor to consider when predicting how the characteristics of future phytoplankton populations will have an impact on biogeochemical cycles and higher trophic levels in marine food webs. %B The ISME Journal %P 1–10 %G eng %U http://www.nature.com/doifinder/10.1038/ismej.2015.102 %R 10.1038/ismej.2015.102 %0 Journal Article %J eLife %D 2015 %T Evolution of alternative biosynthetic pathways for vitamin C following plastid acquisition in photosynthetic eukaryotes %A Wheeler, Glen %A Ishikawa, Takahiro %A Pornsaksit, Varissa %A Smirnoff, Nicholas %K ascorbate %K evolutionary biology %K Galdieria %K genomics %K L-gulonolactone oxidase %K plant biology %K Porphyra %K RCC299 %K vitamin C %X Ascorbic acid (vitamin C) is an enzyme co-factor in eukaryotes that also plays a critical role in protecting photosynthetic eukaryotes against damaging reactive oxygen species derived from the chloroplast. Many animal lineages, including primates, have become ascorbate auxotrophs due to the loss of the terminal enzyme in their biosynthetic pathway, L-gulonolactone oxidase (GULO). The alternative pathways found in land plants and Euglena use a different terminal enzyme, L-galactonolactone dehydrogenase (GLDH). The evolutionary processes leading to these differing pathways and their contribution to the cellular roles of ascorbate remain unclear. Here we present molecular and biochemical evidence demonstrating that GULO was functionally replaced with GLDH in photosynthetic eukaryote lineages following plastid acquisition. GULO has therefore been lost repeatedly throughout eukaryote evolution. The formation of the alternative biosynthetic pathways in photosynthetic eukaryotes uncoupled ascorbate synthesis from hydrogen peroxide production and likely contributed to the rise of ascorbate as a major photoprotective antioxidant. %B eLife %V 4 %P 1–25 %G eng %R 10.7554/eLife.06369 %0 Journal Article %J PloS one %D 2015 %T Guanchochroma wildpretii gen. et spec. nov. (ochrophyta) provides new insights into the diversification and evolution of the algal class synchromophyceae. %A Schmidt, Maria %A Horn, Susanne %A Ehlers, Katrin %A Wilhelm, Christian %A Schnetter, Reinhard %K rcc %X A new relative of the chrysophyte genus Chrysopodocystis was found in Tenerife and termed Guanchochroma wildpretii. This unicellular alga was most noticeably discernible from Chrysopodocystis socialis (the only species of this genus) by the presence of a cyst-like stage with a multilayered lorica, which also functions as a dispersal unit and shows secondary wall growth. Secondary expansion of loricae (cell casings not involved in cell division, usually with a more or less pronounced opening) has never been observed previously and marks a unique feature of the new taxon. Plastids are non-randomly distributed within cells of G. wildpretii. 18S rRNA gene analyses identified the two species as sister lineages and placed them in a monophyletic group with the Synchromophyceae, a heterokont algal (Ochrophyta) class characterized by the presence of chloroplast complexes. Yet, neither Chrysopodocystis nor Guanchochroma showed this feature in ultrastructure analyses. Additionally, their 18S rRNA genes possessed distinct inserts, the highest GC-content known for Ochrophyta and exceptionally long branches on the Ochrophyta 18S rDNA phylogenetic tree, suggesting substantially increased substitution rates along their branch compared to Synchromophyceae. Plastid marker data (rbcL) recovered a monophyletic clade of Chrysopodocystis, Guanchochroma and Synchromophyceae as well, yet with lower supports for internal split order due to limited resolution of the marker. Evidence for the sequence of events leading to the formation of the plastid complex of Synchromophyceae still remains ambiguous because of the apparently short timeframe in which they occurred. %B PloS one %V 10 %P e0131821 %8 jan %G eng %U http://dx.doi.org/10.1371/journal.pone.0131821 %R 10.1371/journal.pone.0131821 %0 Journal Article %J Environmental microbiology reports %D 2015 %T Interplay between the genetic clades of ¡i¿Micromonas¡/i¿ and their viruses in the Western English Channel. %A Baudoux, A-C %A Lebredonchel, H %A Dehmer, H %A Latimier, M %A Edern, R %A Rigaut-Jalabert, F %A Ge, P %A Guillou, L %A Foulon, E %A Bozec, Y %A Cariou, T %A Desdevises, Y %A Derelle, E %A Grimsley, N %A Moreau, H %A Simon, N %K 2015 %K rcc %K RCC?o?dd %K sbr?hyto$_\textrmd$ipo %X The genus Micromonas comprises distinct genetic clades that commonly dominate eukaryotic phytoplankton community from polar to tropical waters. This phytoplankter is also recurrently infected by abundant and genetically diverse prasinoviruses. Here we report on the interplay between prasinoviruses and Micromonas with regards to the genetic diversity of this host. During one year, we monitored the abundance of 3 clades of Micromonas and their viruses in the Western English Channel both in the environment, using clade-specific probes and flow cytometry, and in the laboratory, using clonal strains of Micromonas clades to assay for their viruses by plaque-forming units. We showed that the seasonal fluctuations of Micromonas clades were closely mirrored by the abundances of their corresponding viruses, indicating that the members of Micromonas genus are susceptible to viral infection, regardless of their genetic affiliation. The characterization of 45 viral isolates revealed that Micromonas clades are attacked by specific virus populations, which exhibit distinctive clade specificity, life strategies, and genetic diversity. However, some viruses can also cross-infect different host clades suggesting a mechanism of horizontal gene transfer within Micromonas genus. This study provides novel insights into the impact of viral infection for the ecology and evolution of the prominent phytoplankter Micromonas. %B Environmental microbiology reports %8 jun %G eng %U http://www.ncbi.nlm.nih.gov/pubmed/26081716 %R 10.1111/1758-2229.12309 %0 Journal Article %J Molecular biology and evolution %D 2015 %T Intron invasions trace algal speciation and reveal nearly identical Arctic and Antarctic Micromonas populations. %A Simmons, Melinda P %A Bachy, Charles %A Sudek, Sebastian %A van Baren, Marijke J %A Sudek, Lisa %A Ares, Manuel %A Worden, Alexandra Z %K rcc %X Spliceosomal introns are a hallmark of eukaryotic genes that are hypothesized to play important roles in genome evolution but have poorly understood origins. Although most introns lack sequence homology to each other, recently new families of spliceosomal introns that are repeated hundreds of times in individual genomes have been discovered in a few organisms. The prevalence and conservation of these introner elements (IEs) or introner-like elements (ILEs) in other taxa, as well as their evolutionary relationships to regular spliceosomal introns, are still unknown. Here, we systematically investigate introns in the widespread marine green alga Micromonas and report new families of IEs, numerous intron presence-absence polymorphisms, and potential intron insertion hot-spots. The new families enabled identification of conserved IE secondary structure features and establishment of a novel general model for repetitive intron proliferation across genomes. Despite shared secondary structure, the IE families from each Micromonas lineage bear no obvious sequence similarity to those in the other lineages, suggesting their appearance is intimately linked with the process of speciation. Two of the new IE families come from an Arctic culture (Micromonas Clade E2) isolated from a polar region where this alga is increasing in abundance due to climate change. The same two families were detected in metagenomic data from Antarctica - a system where Micromonas has never before been reported. Strikingly high identity between the Arctic isolate and Antarctic coding sequences that flank the IEs suggests connectivity between populations in the two polar systems that we postulate occurs through deep-sea currents. Recovery of Clade E2 sequences in North Atlantic Deep Waters beneath the Gulf Stream supports this hypothesis. Our work illuminates the dynamic relationships between an unusual class of repetitive introns, genome evolution, speciation and global distribution of this sentinel marine alga. %B Molecular biology and evolution %8 may %G eng %U http://mbe.oxfordjournals.org/cgi/content/long/msv122v1 %R 10.1093/molbev/msv122 %0 Journal Article %J Frontiers in Microbiology %D 2015 %T Paralytic shellfish toxin content is related to genomic sxtA4 copy number in Alexandrium minutum strains %A Stüken, Anke %A Riobó, Pilar %A Franco, José %A Jakobsen, Kjetill S. %A Guillou, Laure %A Figueroa, Rosa I. %K 2015 %K Alexandrium %K copy %K copy number variation %K Dinoflagellate %K gene dosage %K genome size %K number variation %K paralytic shellfish toxin %K paralytic shellfish toxin (PST) %K pst %K rcc %K RCC?o?dd %K saxitoxin %K saxitoxin (STX) %K sbr?hyto$_\textrmd$ipo %K stx %K sxtA %X Dinoflagellates are microscopic aquatic eukaryotes with huge genomes and an unusual cell regulation. For example, most genes are present in numerous copies and all copies seem to be obligatorily transcribed. The consequence of the gene copy number (CPN) for final protein synthesis is, however, not clear. One such gene is sxtA, the starting gene of paralytic shellfish toxin (PST) synthesis. PSTs are small neurotoxic compounds that can accumulate in the food chain and cause serious poisoning incidences when ingested. They are produced by dinoflagellates of the genera Alexandrium, Gymnodium, and Pyrodinium. Here we investigated if the genomic CPN of sxtA4 is related to PST content in Alexandrium minutum cells. SxtA4 is the 4th domain of the sxtA gene and its presence is essential for PST synthesis in dinoflagellates. We used PST and genome size measurements as well as quantitative PCR to analyze sxtA4 CPN and toxin content in 15 A. minutum strains. Our results show a strong positive correlation between the sxtA4 CPN and the total amount of PST produced in actively growing A. minutum cells. This correlation was independent of the toxin profile produced, as long as the strain contained the genomic domains sxtA1 and sxtA4. %B Frontiers in Microbiology %V 6 %P 1–10 %G eng %U http://journal.frontiersin.org/article/10.3389/fmicb.2015.00404 %R 10.3389/fmicb.2015.00404 %0 Journal Article %J Journal of Experimental Marine Biology and Ecology %D 2015 %T Phosphorus availability modifies carbon production in Coccolithus pelagicus (Haptophyta) %A Gerecht, A.C. %A Šupraha, L. %A Edvardsen, B. %A Langer, G. %A Henderiks, J. %K Calcification %K Carbon production %K Coccolithus pelagicus %K Phosphorus limitation %K RCC1200 %K Semi-continuous culture %X The coccolithophore Coccolithus pelagicus (Wallich) Schiller fixes CO¡inf¿2¡/inf¿ into particulate organic carbon (POC) through photosynthesis and into particulate inorganic carbon (PIC) in the form of calcite. To examine the role of phosphorus (P) availability in the production of POC and PIC, C. pelagicus subsp. braarudii (Gaarder) Geisen et al. was grown in semi-continuous cultures at three initial phosphate concentrations (P-replete, 1, and 0.5??M [P]). Reduced P-availability (1 and 0.5??M [P]) decreased POC production, while PIC production only decreased when phosphate concentrations became growth limiting (0.5??M [P]). This decrease has not been observed previously in batch cultures, highlighting the inadequacy of the batch culture approach with regard to determining carbon production. The reduction in growth rate by 50% at 0.5??M [P] was accompanied by a doubling in cell volume (and POC). PIC production was halved, resulting in a lowered PIC to POC ratio. The average number of coccoliths per cell (and PIC content) remained the same among treatments, despite the significant change in cell size. Our data suggest that POC production in C. pelagicus is more sensitive towards a moderate reduction in phosphorus availability than PIC production. Once phosphorus availability limits cell division, however, phosphorus resources are invested into POC rather than PIC production. This reduces cell density and sinking rates, indicating that coccoliths do not act as ballast for reaching deeper nutrient-rich layers under nutrient limitation. %B Journal of Experimental Marine Biology and Ecology %V 472 %P 24–31 %8 nov %G eng %U http://linkinghub.elsevier.com/retrieve/pii/S0022098115001756 %R 10.1016/j.jembe.2015.06.019 %0 Journal Article %J Molecular Ecology Resources %D 2015 %T PhytoREF: a reference database of the plastidial 16S rRNA gene of photosynthetic eukaryotes with curated taxonomy %A Decelle, Johan %A Romac, Sarah %A Stern, Rowena F. %A Bendif, El Mahdi %A Zingone, Adriana %A Audic, Stéphane %A Guiry, Michael D. %A Guillou, Laure %A Tessier, Désiré %A Le Gall, Florence %A Gourvil, Priscillia %A dos Santos, Adriana Lopes %A Probert, Ian %A Vaulot, Daniel %A de Vargas, Colomban %A Christen, Richard %K 2015 %K MACUMBA %K rcc %K RCC?o?dd %K SBR$_\textrmP$hyto$_\textrmD$IPO %K SBR$_\textrmP$hyto$_\textrmE$PPO %K sbr?hyto$_\textrmd$ipo %K sbr?hyto?ppo %X Photosynthetic eukaryotes have a critical role as the main producers in most ecosystems of the biosphere. The ongo- ing environmental metabarcoding revolution opens the perspective for holistic ecosystems biological studies of these organisms, in particular the unicellular microalgae that often lack distinctive morphological characters and have complex life cycles. To interpret environmental sequences, metabarcoding necessarily relies on taxonomically curated databases containing reference sequences of the targeted gene (or barcode) from identified organisms. To date, no such reference framework exists for photosynthetic eukaryotes. In this study, we built the PhytoREF data- base that contains 6490 plastidial 16S rDNA reference sequences that originate from a large diversity of eukaryotes representing all known major photosynthetic lineages. We compiled 3333 amplicon sequences available from public databases and 879 sequences extracted from plastidial genomes, and generated 411 novel sequences from cultured marine microalgal strains belonging to different eukaryotic lineages. A total of 1867 environmental Sanger 16S rDNA sequences were also included in the database. Stringent quality filtering and a phylogeny-based taxonomic classifica- tion were applied for each 16S rDNA sequence. The database mainly focuses on marine microalgae, but sequences from land plants (representing half of the PhytoREF sequences) and freshwater taxa were also included to broaden the applicability of PhytoREF to different aquatic and terrestrial habitats. PhytoREF, accessible via a web interface (http://phytoref.fr), is a new resource in molecular ecology to foster the discovery, assessment and monitoring of the diversity of photosynthetic eukaryotes using high-throughput sequencing. %B Molecular Ecology Resources %V 15 %P 1435–1445 %G eng %U http://doi.wiley.com/10.1111/1755-0998.12401 %R 10.1111/1755-0998.12401 %0 Journal Article %J Journal of Phycology %D 2014 %T Brandtodinium gen. nov. and B. nutricula comb. Nov. (Dinophyceae), a dinoflagellate commonly found in symbiosis with polycystine radiolarians %A Probert, Ian %A Siano, Raffaele %A Poirier, Camille %A Decelle, Johan %A Biard, Tristan %A Tuji, Akihiro %A Suzuki, Noritoshi %A Not, Fabrice %K Dinoflagellate %K MACUMBA %K Peridiniales %K polycystines %K Radiolaria %K rcc %K RCC3378 %K RCC3379 %K RCC3380 %K RCC3381 %K RCC3382 %K RCC3383 %K RCC3384 %K RCC3385 %K RCC3386 %K RCC3387 %K RCC3388 %K SBR$_\textrmP$hyto$_\textrmD$PO %K Scrippsiella %K symbiosis %K taxonomy %K Zooxanthella %X Symbiotic interactions between pelagic hosts and microalgae have received little attention, although they are widespread in the photic layer of the world ocean, where they play a fundamental role in the ecology of the planktonic ecosystem. Polycystine radiolarians (including the orders Spumellaria, Collodaria and Nassellaria) are planktonic heterotrophic protists that are widely distributed and often abundant in the ocean. Many polycystines host symbiotic microalgae within their cytoplasm, mostly thought to be the dinoflagellate Scrippsiella nutricula, a species originally described by Karl Brandt in the late nineteenth century as Zooxanthella nutricula. The free-living stage of this dinoflagellate has never been characterized in terms of morphology and thecal plate tabulation. We examined morphological characters and sequenced conservative ribosomal markers of clonal cultures of the free-living stage of symbiotic dinoflagellates isolated from radiolarian hosts from the three polycystine orders. In addition, we sequenced symbiont genes directly from several polycystine-symbiont holobiont specimens from different oceanic regions. Thecal plate arrangement of the free-living stage does not match that of Scrippsiella or related genera, and LSU and SSU rDNA-based molecular phylogenies place these symbionts in a distinct clade within the Peridiniales. Both phylogenetic analyses and the comparison of morphological features of culture strains with those reported for other closely related species support the erection of a new genus that we name Brandtodinium gen. nov. and the recombination of S. nutricula as B. nutricula comb. nov. %B Journal of Phycology %V 50 %P 388–399 %G eng %U http://dx.doi.org/10.1111/jpy.12174 %R 10.1111/jpy.12174 %0 Journal Article %J The ISME Journal %D 2014 %T Comparative genomics reveals surprising divergence of two closely related strains of uncultivated UCYN-A cyanobacteria %A Bombar, Deniz %A Heller, Philip %A Sanchez-Baracaldo, Patricia %A Carter, Brandon J %A Zehr, Jonathan P %K rcc %B The ISME Journal %V 8 %P 2530–2542 %G eng %U http://www.nature.com/doifinder/10.1038/ismej.2014.167 %R 10.1038/ismej.2014.167 %0 Journal Article %J The ISME journal %D 2014 %T Connecting thermal physiology and latitudinal niche partitioning in marine Synechococcus %A Pittera, Justine %A Humily, Florian %A Thorel, Maxine %A Grulois, Daphne %A Garczarek, Laurence %A Six, Christophe %K 2014 %K adaptation %K ecotype %K MACUMBA %K marine cyanobacteria %K MicroB3 %K rcc %K SBR$_\textrmP$hyto$_\textrmP$PM %K sbr?hyto?app %K Synechococcus %K temperature %X Marine Synechococcus cyanobacteria constitute a monophyletic group that displays a wide latitudinal distribution, ranging from the equator to the polar fronts. Whether these organisms are all physiologically adapted to stand a large temperature gradient or stenotherms with narrow growth temperature ranges has so far remained unexplored. We submitted a panel of six strains, isolated along a gradient of latitude in the North Atlantic Ocean, to long- and short-term variations of temperature. Upon a downward shift of temperature, the strains showed strikingly distinct resistance, seemingly related to their latitude of isolation, with tropical strains collapsing while northern strains were capable of growing. This behaviour was associated to differential photosynthetic performances. In the tropical strains, the rapid photosystem II inactivation and the decrease of the antioxydant [beta]-carotene relative to chl a suggested a strong induction of oxidative stress. These different responses were related to the thermal preferenda of the strains. The northern strains could grow at 10[thinsp][deg]C while the other strains preferred higher temperatures. In addition, we pointed out a correspondence between strain isolation temperature and phylogeny. In particular, clades I and IV laboratory strains were all collected in the coldest waters of the distribution area of marine Synechococus. We, however, show that clade I Synechococcus exhibit different levels of adaptation, which apparently reflect their location on the latitudinal temperature gradient. This study reveals the existence of lineages of marine Synechococcus physiologically specialised in different thermal niches, therefore suggesting the existence of temperature ecotypes within the marine Synechococcus radiation. %B The ISME journal %V 8 %P 1221–1236 %G eng %U http://dx.doi.org/10.1038/ismej.2013.228 10.1038/ismej.2013.228 %R 10.1038/ismej.2013.228 %0 Journal Article %J BMC Evolutionary Biology %D 2014 %T Cophylogenetic interactions between marine viruses and eukaryotic picophytoplankton %A Bellec, Laure %A Clerissi, Camille %A Edern, Roseline %A Foulon, Elodie %A Simon, Nathalie %A Grimsley, Nigel %A Desdevises, Yves %K rcc %K RCC1105 %K rcc1107 %K RCC1108 %K RCC1109 %K RCC114 %K RCC2482 %K RCC2483 %K RCC2484 %K RCC2485 %K RCC344 %K RCC356 %K RCC373 %K RCC418 %K RCC461 %K RCC464 %K RCC465 %K RCC629 %K RCC658 %K RCC745 %K RCC789 %K RCC834 %K SBR$_\textrmP$hyto$_\textrmD$PO %X BACKGROUND:Numerous studies have investigated cospeciation (or cophylogeny) in various host-symbiont systems, and different patterns were inferred, from strict cospeciation where symbiont phylogeny mirrors host phylogeny, to complete absence of correspondence between trees. The degree of cospeciation is generally linked to the level of host specificity in the symbiont species and the opportunity they have to switch hosts. In this study, we investigated cophylogeny for the first time in a microalgae-virus association in the open sea, where symbionts are believed to be highly host-specific but have wide opportunities to switch hosts. We studied prasinovirus-Mamiellales associations using 51 different viral strains infecting 22 host strains, selected from the characterisation and experimental testing of the specificities of 313 virus strains on 26 host strains.RESULTS:All virus strains were restricted to their host genus, and most were species-specific, but some of them were able to infect different host species within a genus. Phylogenetic trees were reconstructed for viruses and their hosts, and their congruence was assessed based on these trees and the specificity data using different cophylogenetic methods, a topology-based approach, Jane, and a global congruence method, ParaFit. We found significant congruence between virus and host trees, but with a putatively complex evolutionary history.CONCLUSIONS:Mechanisms other than true cospeciation, such as host-switching, might explain a part of the data. It has been observed in a previous study on the same taxa that the genomic divergence between host pairs is larger than between their viruses. It implies that if cospeciation predominates in this algae-virus system, this would support the hypothesis that prasinoviruses evolve more slowly than their microalgal hosts, whereas host switching would imply that these viruses speciated more recently than the divergence of their host genera. %B BMC Evolutionary Biology %V 14 %P 59 %G eng %U http://www.biomedcentral.com/1471-2148/14/59 %R 10.1186/1471-2148-14-59 %0 Journal Article %J Harmful Algae %D 2014 %T Genetic diversity of the harmful family Kareniaceae (Gymnodiniales, Dinophyceae) in France, with the description of ¡i¿Karlodinium gentienii¡/i¿ sp. nov.: A new potentially toxic dinoflagellate %A Nézan, Elisabeth %A Siano, Raffaele %A Boulben, Sylviane %A Six, Christophe %A Bilien, Gwenael %A Chèze, Karine %A Duval, Audrey %A Le Panse, Sophie %A Quéré, Julien %A Chomérat, Nicolas %K 2014 %K rcc %K sbr?hyto?app %X A B S T R A C T The family Kareniaceae is mostly known in France for recurrent blooms of Karenia mikimotoi in the Atlantic, English Channel, and Mediterranean Sea and for the unusual green discoloration in the saltwater lagoon of Diana (Corsica) caused by Karlodinium corsicum in April 1994. In terms of diversity, this taxonomic group was long overlooked owing to the difficult identification of these small unarmored dinoflagellates. In this study, thanks to the molecular characterization performed on single cells from field samples and cultures, twelve taxonomic units were assigned to the known genera Karenia, Karlodinium and Takayama, whereas one could not be affiliated to any described genus. The molecular phylogeny inferred from the D1–D2 region of the LSU rDNA showed that five of them formed a sister taxon of a known species, and could not be identified at species-level, on the basis of molecular analysis only. Among these latter taxa, one Karlodinium which was successfully cultured was investigated by studying the external morphological features (using two procedures for cells fixation), ultrastructure, pigment composition, and haemolytic activity. The results of our analyses corroborate the genetic results in favour of the erection of Karlodinium gentienii sp. nov., which possesses an internal complex system of trichocysts connected to external micro-processes particularly abundant in the epicone, and a peculiar pigment composition. In addition, preliminary assays showed a haemolytic activity. %B Harmful Algae %V 40 %P 75–91 %G eng %U http://linkinghub.elsevier.com/retrieve/pii/S1568988314001863 %R 10.1016/j.hal.2014.10.006 %0 Journal Article %J Proceedings of the National Academy of Sciences of the United States of America %D 2014 %T Marine algae and land plants share conserved phytochrome signaling systems %A Duanmu, Deqiang %A Bachy, Charles %A Sudek, Sebastian %A Wong, Chee-Hong %A Jimenez, Valeria %A Rockwell, Nathan C %A Martin, Shelley S %A Ngan, Chew Yee %A Reistetter, Emily N %A van Baren, Marijke J %A Price, Dana C %A Wei, Chia-Lin %A Reyes-Prieto, Adrian %A Lagarias, J Clark %A Worden, Alexandra Z %K Micromonas %K rcc %X Phytochrome photosensors control a vast gene network in streptophyte plants, acting as master regulators of diverse growth and developmental processes throughout the life cycle. In contrast with their absence in known chlorophyte algal genomes and most sequenced prasinophyte algal genomes, a phytochrome is found in Micromonas pusilla, a widely distributed marine picoprasinophyte (¡2 µm cell diameter). Together with phytochromes identified from other prasinophyte lineages, we establish that prasinophyte and streptophyte phytochromes share core light-input and signaling-output domain architectures except for the loss of C-terminal response regulator receiver domains in the streptophyte phytochrome lineage. Phylogenetic reconstructions robustly support the presence of phytochrome in the common progenitor of green algae and land plants. These analyses reveal a monophyletic clade containing streptophyte, prasinophyte, cryptophyte, and glaucophyte phytochromes implying an origin in the eukaryotic ancestor of the Archaeplastida. Transcriptomic measurements reveal diurnal regulation of phytochrome and bilin chromophore biosynthetic genes in Micromonas. Expression of these genes precedes both light-mediated phytochrome redistribution from the cytoplasm to the nucleus and increased expression of photosynthesis-associated genes. Prasinophyte phytochromes perceive wavelengths of light transmitted farther through seawater than the red/far-red light sensed by land plant phytochromes. Prasinophyte phytochromes also retain light-regulated histidine kinase activity lost in the streptophyte phytochrome lineage. Our studies demonstrate that light-mediated nuclear translocation of phytochrome predates the emergence of land plants and likely represents a widespread signaling mechanism in unicellular algae. %B Proceedings of the National Academy of Sciences of the United States of America %V 111 %P 15827–15832 %G eng %U http://www.pnas.org/content/111/44/15827.abstract %R 10.1073/pnas.1416751111 %0 Journal Article %J PLoS biology %D 2014 %T The Marine Microbial Eukaryote Transcriptome Sequencing Project (MMETSP): illuminating the functional diversity of eukaryotic life in the oceans through transcriptome sequencing %A Keeling, Patrick J %A Burki, Fabien %A Wilcox, Heather M %A Allam, Bassem %A Allen, Eric E %A Amaral-Zettler, Linda A %A Armbrust, E Virginia %A Archibald, John M %A Bharti, Arvind K %A Bell, Callum J %A Beszteri, Bank %A Bidle, Kay D %A Cameron, Connor T %A Campbell, Lisa %A Caron, David A %A Cattolico, Rose Ann %A Collier, Jackie L %A Coyne, Kathryn %A Davy, Simon K %A Deschamps, Phillipe %A Dyhrman, Sonya T %A Edvardsen, Bente %A Gates, Ruth D %A Gobler, Christopher J %A Greenwood, Spencer J %A Guida, Stephanie M %A Jacobi, Jennifer L %A Jakobsen, Kjetill S %A James, Erick R %A Jenkins, Bethany %A John, Uwe %A Johnson, Matthew D %A Juhl, Andrew R %A Kamp, Anja %A Katz, Laura A %A Kiene, Ronald %A Kudryavtsev, Alexander %A Leander, Brian S %A Lin, Senjie %A Lovejoy, Connie %A Lynn, Denis %A Marchetti, Adrian %A McManus, George %A Nedelcu, Aurora M %A Menden-Deuer, Susanne %A Miceli, Cristina %A Mock, Thomas %A Montresor, Marina %A Moran, Mary Ann %A Murray, Shauna %A Nadathur, Govind %A Nagai, Satoshi %A Ngam, Peter B %A Palenik, Brian %A Pawlowski, Jan %A Petroni, Giulio %A Piganeau, Gwenael %A Posewitz, Matthew C %A Rengefors, Karin %A Romano, Giovanna %A Rumpho, Mary E %A Rynearson, Tatiana %A Schilling, Kelly B %A Schroeder, Declan C %A Simpson, Alastair G B %A Slamovits, Claudio H %A Smith, David R %A Smith, G Jason %A Smith, Sarah R %A Sosik, Heidi M %A Stief, Peter %A Theriot, Edward %A Twary, Scott N %A Umale, Pooja E %A Vaulot, Daniel %A Wawrik, Boris %A Wheeler, Glen L %A Wilson, William H %A Xu, Yan %A Zingone, Adriana %A Worden, Alexandra Z %K 2014 %K rcc %K SBR$_\textrmP$hyto$_\textrmD$PO %K sbr?hyto$_\textrmd$ipo %X Current sampling of genomic sequence data from eukaryotes is relatively poor, biased, and inadequate to address important questions about their biology, evolution, and ecology; this Community Page describes a resource of 700 transcriptomes from marine microbial eukaryotes to help understand their role in the world's oceans %B PLoS biology %V 12 %P e1001889 %G eng %U http://dx.doi.org/10.1371%252Fjournal.pbio.1001889 %R 10.1371/journal.pbio.1001889 %0 Journal Article %J Current Biology %D 2014 %T A novel protein, ubiquitous in marine phytoplankton, concentrates iron at the cell surface and facilitates uptake %A Morrissey, Joe %A Sutak, Robert %A Paz-Yepes, Javier %A Tanaka, Atsuko %A Moustafa, Ahmed %A Veluchamy, Alaguraj %A Thomas, Yann %A Botebol, Hugo %A Bouget, François-Yves %A McQuaid, Jeffrey B. %A Tirichine, Leila %A Allen, Andrew E. %A Lesuisse, Emmanuel %A Bowler, Chris %K rcc %X Numerous cellular functions including respiration require iron. Plants and phytoplankton must also maintain the iron-rich photosynthetic electron transport chain, which most likely evolved in the iron-replete reducing environments of the Proterozoic ocean [1]. Iron bioavailability has drastically decreased in the contemporary ocean [1], most likely selecting for the evolution of efficient iron acquisition mechanisms among modern phytoplankton. Mesoscale iron fertilization experiments often result in blooms dominated by diatoms [2], indicating that diatoms have adaptations that allow survival in iron-limited waters and rapid multiplication when iron becomes available. Yet the genetic and molecular bases are unclear, as very few iron uptake genes have been functionally characterized from marine eukaryotic phytoplankton, and large portions of diatom iron starvation transcriptomes are genes encoding unknown functions [3–5]. Here we show that the marine diatom Phaeodactylum tricornutum utilizes ISIP2a to concentrate Fe(III) at the cell surface as part of a novel, copper-independent and thermodynamically controlled iron uptake system. ISIP2a is expressed in response to iron limitation several days prior to the induction of ferrireductase activity, and it facilitates significant Fe(III) uptake during the initial response to Fe limitation. ISIP2a is able to directly bind Fe(III) and increase iron uptake when heterologously expressed, whereas knockdown of ISIP2a in P. tricornutum decreases iron uptake, resulting in impaired growth and chlorosis during iron limitation. ISIP2a is expressed by diverse marine phytoplankton, indicating that it is an ecologically significant adaptation to the unique nutrient composition of marine environments. %B Current Biology %V 25 %P 364–371 %8 dec %G eng %U http://www.sciencedirect.com/science/article/pii/S0960982214015632 %R 10.1016/j.cub.2014.12.004 %0 Journal Article %J Trends in Ecology & Evolution %D 2014 %T The others: our biased perspective of eukaryotic genomes %A del Campo, Javier %A Sieracki, Michael E %A Molestina, Robert %A Keeling, Patrick %A Massana, Ramon %A Ruiz-Trillo, Iñaki %K rcc %X ?There is an important bias in eukaryotic knowledge, affecting cultures and genomes.?Eukaryotic genomics are biased towards multicellular organisms and their parasites.?A phylogeny-driven initiative is needed to overcome the eukaryotic genomic bias.?We propose to sequence neglected cultures and increase culturing efforts.?Single-cell genomics should be embraced as a tool to explore eukaryotic diversity. %B Trends in Ecology & Evolution %V 29 %P 252–259 %G eng %U http://www.cell.com/trends/ecology-evolution/abstract/S0169-5347(14)00064-0 %R 10.1016/j.tree.2014.03.006 %0 Journal Article %J Protist %D 2014 %T Parvilucifera rostrata sp. nov., a novel parasite in the phylum Perkinsozoa that infects the toxic dinoflagellate Alexandrium minutum (Dinophyceae) %A Lepelletier, F %A Karpov, S A %A Le Panse, S %A Bigeard, E %A Skovgaard, A %A Jeanthon, C %A Guillou, L %K 2014 %K MACUMBA %K rcc %K SBR$_\textrmP$hyto$_\textrmD$PO %K SBR$_\textrmP$hyto$_\textrmP$PM %K sbr?hyto$_\textrmd$ipo %K sbr?hyto?app %B Protist %V 165 %P 31–49 %G eng %R 10.1016/j.protis.2013.09.005 %0 Journal Article %J Science %D 2014 %T Single-cell genomics reveals hundreds of coexisting subpopulations in wild prochlorococcus %A Kashtan, Nadav %A Roggensack, Sara E %A Rodrigue, Sébastien %A Thompson, Jessie W %A Biller, Steven J %A Coe, Allison %A Ding, Huiming %A Marttinen, Pekka %A Malmstrom, Rex R %A Stocker, Roman %A Follows, Michael J %A Stepanauskas, Ramunas %A Chisholm, Sallie W %K RCC278 %X Extensive genomic diversity within coexisting members of a microbial species has been revealed through selected cultured isolates and metagenomic assemblies. Yet, the cell-by-cell genomic composition of wild uncultured populations of co-occurring cells is largely unknown. In this work, we applied large-scale single-cell genomics to study populations of the globally abundant marine cyanobacterium Prochlorococcus. We show that they are composed of hundreds of subpopulations with distinct “genomic backbones,” each backbone consisting of a different set of core gene alleles linked to a small distinctive set of flexible genes. These subpopulations are estimated to have diverged at least a few million years ago, suggesting ancient, stable niche partitioning. Such a large set of coexisting subpopulations may be a general feature of free-living bacterial species with huge populations in highly mixed habitats. %B Science %V 344 %P 416–420 %G eng %U http://www.sciencemag.org/content/344/6182/416.abstract %R 10.1126/science.1248575 %0 Journal Article %J Journal of Phycology %D 2014 %T Transcriptomic insights into the life history of bolidophytes , the sister lineage to diatoms %A Kessenich, Colton R %A Ruck, Elizabeth C %A Schurko, Andrew M %A Wickett, Norman J %A Alverson, Andrew J %K Bolidomonas %K CCMP1866 %K diatoms %K diplontic %K haplodiplontic %K life cycle %K Parmales %K RCC205 %K RCC?o?dd %K Transcriptome %X Diatoms are perhaps the most diverse lineage of eukaryotic algae, with their siliceous cell wall and diplontic life history often considered to have played important roles in their extraordinary diversification. The characteristic diminution of the diatom cell wall over the course of vegetative growth provides a reliable, intrinsic trigger for sexual reproduction, establishing a direct link between the evolution of their cell-wall and life- history features. It is unclear, however, whether the diplontic life cycle of diatoms represents an ancestral or derived trait. This uncertainty is based in part on our lack of understanding of the life cycle of the sister lineage to diatoms, which includes a mix of two free-living and separately classified forms: naked biflagellate unicells in the genus Bolidomonas and silicified forms in the order Parmales. These two forms might represent different life-history stages, although directly establishing such links can be difficult. We sequenced transcriptomes for Bolidomonas and two diatoms and found that \~0.1% of the coding regions in the two diploid diatoms are heterozygous, whereas Bolidomonas is virtually devoid of heterozygous alleles, consistent with expectations for a haploid genome. These results suggest that Bolidomonas is haploid and predict that parmaleans represent the diploid phase of a haplodiplontic life cycle. These data fill an important gap in our understanding of the origin of the diplontic life history of diatoms, which may represent an evolutionarily derived, adaptive feature. %B Journal of Phycology %V 983 %P 977–983 %G eng %U http://dx.doi.org/10.1111/jpy.12222 %R 10.1111/jpy.12222 %0 Journal Article %J Journal of Applied Phycology %D 2013 %T On the description of Tisochrysis lutea gen . nov . sp . nov . and Isochrysis nuda sp. nov. in the Isochrysidales, and the transfer of Dicrateria to the Prymnesiales (Haptophyta) %A Bendif, El Mahdi %A Probert, Ian %A Schroeder, Declan C %A de Vargas, Colomban %K 2013 %K dicrateria %K imantonia %K isochrysidaceae %K isochrysis galbana %K phylogeny %K rcc %K RCC1195 %K RCC1207 %K RCC1281 %K RCC1286 %K RCC1344 %K RCC1346 %K RCC1347 %K RCC1348 %K RCC1349 %K RCC1350 %K RCC1353 %K RCC2477 %K RCC3681 %K RCC3684 %K RCC3686 %K RCC3687 %K RCC3690 %K RCC3691 %K RCC3692 %K RCC3693 %K RCC3694 %K RCC3695 %K RCC3696 %K RCC3699 %K RCC3701 %K RCC3707 %K SBR$_\textrmP$hyto$_\textrmE$PPO %K sbr?hyto?ppo %K taxonomy %K ultrastructure %B Journal of Applied Phycology %V 25 %P 1763–1776 %G eng %R 10.1007/s10811-013-0037-0 %0 Journal Article %J The ISME journal %D 2013 %T Gene invasion in distant eukaryotic lineages: discovery of mutually exclusive genetic elements reveals marine biodiversity %A Monier, Adam %A Sudek, Sebastian %A Fast, Naomi M %A Worden, Alexandra Z %K horizontal transfer %K inteins %K invasive elements %K metagenomics %K Micromonas %K polymorphic introns %K rcc %K viridiplantae %B The ISME journal %V 7 %P 1764–1774 %G eng %U http://dx.doi.org/10.1038/ismej.2013.70 10.1038/ismej.2013.70 %R 10.1038/ismej.2013.70 %0 Journal Article %J PLoS ONE %D 2013 %T A gene island with two possible configurations is involved in chromatic acclimation in marine synechococcus %A Humily, Florian %A Partensky, Frédéric %A Six, Christophe %A Farrant, Gregory K %A Ratin, Morgane %A Marie, Dominique %A Garczarek, Laurence %K 2013 %K MACUMBA %K MicroB3 %K rcc %K SBR$_\textrmP$hyto$_\textrmP$PM %K sbr?hyto?app %X ¡p¿¡italic¿Synechococcus¡/italic¿, the second most abundant oxygenic phototroph in the marine environment, harbors the largest pigment diversity known within a single genus of cyanobacteria, allowing it to exploit a wide range of light niches. Some strains are capable of Type IV chromatic acclimation (CA4), a process by which cells can match the phycobilin content of their phycobilisomes to the ambient light quality. Here, we performed extensive genomic comparisons to explore the diversity of this process within the marine ¡italic¿Synechococcus¡/italic¿ radiation. A specific gene island was identified in all CA4-performing strains, containing two genes (¡italic¿fciA¡/italic¿/b) coding for possible transcriptional regulators and one gene coding for a phycobilin lyase. However, two distinct configurations of this cluster were observed, depending on the lineage. CA4-A islands contain the ¡italic¿mpeZ¡/italic¿ gene, encoding a recently characterized phycoerythrobilin lyase-isomerase, and a third, small, possible regulator called ¡italic¿fciC¡/italic¿. In CA4-B islands, the lyase gene encodes an uncharacterized relative of MpeZ, called MpeW. While ¡italic¿mpeZ¡/italic¿ is expressed more in blue light than green light, this is the reverse for ¡italic¿mpeW¡/italic¿, although only small phenotypic differences were found among chromatic acclimaters possessing either CA4 island type. This study provides novel insights into understanding both diversity and evolution of the CA4 process.¡/p¿ %B PLoS ONE %V 8 %P e84459 %G eng %U http://dx.doi.org/10.1371/journal.pone.0084459 %R 10.1371/journal.pone.0084459 %0 Journal Article %J Proceedings of the National Academy of Sciences %D 2013 %T Genome structure and metabolic features in the red seaweed Chondrus crispus shed light on evolution of the Archaeplastida %A Collen, Jonas %A Porcel, Betina %A Carré, Wilfrid %A Ball, Steven G %A Chaparro, Cristian %A Tonon, Thierry %A Barbeyron, Tristan %A Michel, Gurvan %A Noel, Benjamin %A Valentin, Klaus %A Elias, Marek %A Artiguenave, François %A Arun, Alok %A Aury, Jean-Marc %A Barbosa-Neto, José F %A Bothwell, John H %A Bouget, François-Yves %A Brillet, Loraine %A Cabello-Hurtado, Francisco %A Capella-Gutiérrez, Salvador %A Charrier, Bénédicte %A Cladière, Lionel %A Cock, J Mark %A Coelho, Susana M %A Colleoni, Christophe %A Czjzek, Mirjam %A Da Silva, Corinne %A Delage, Ludovic %A Denoeud, France %A Deschamps, Philippe %A Dittami, Simon M %A Gabaldón, Toni %A Gachon, Claire M M %A Groisillier, Agnès %A Hervé, Cécile %A Jabbari, Kamel %A Katinka, Michael %A Kloareg, Bernard %A Kowalczyk, Nathalie %A Labadie, Karine %A Leblanc, Catherine %A Lopez, Pascal J %A McLachlan, Deirdre H %A Meslet-Cladiere, Laurence %A Moustafa, Ahmed %A Nehr, Zofia %A Nyvall Collén, Pi %A Panaud, Olivier %A Partensky, Frédéric %A Poulain, Julie %A Rensing, Stefan A %A Rousvoal, Sylvie %A Samson, Gaelle %A Symeonidi, Aikaterini %A Weissenbach, Jean %A Zambounis, Antonios %A Wincker, Patrick %A Boyen, Catherine %K RCC299 %X Red seaweeds are key components of coastal ecosystems and are economically important as food and as a source of gelling agents, but their genes and genomes have received little attention. Here we report the sequencing of the 105-Mbp genome of the florideophyte Chondrus crispus (Irish moss) and the annotation of the 9,606 genes. The genome features an unusual structure characterized by gene-dense regions surrounded by repeat-rich regions dominated by transposable elements. Despite its fairly large size, this genome shows features typical of compact genomes, e.g., on average only 0.3 introns per gene, short introns, low median distance between genes, small gene families, and no indication of large-scale genome duplication. The genome also gives insights into the metabolism of marine red algae and adaptations to the marine environment, including genes related to halogen metabolism, oxylipins, and multicellularity (microRNA processing and transcription factors). Particularly interesting are features related to carbohydrate metabolism, which include a minimalistic gene set for starch biosynthesis, the presence of cellulose synthases acquired before the primary endosymbiosis showing the polyphyly of cellulose synthesis in Archaeplastida, and cellulases absent in terrestrial plants as well as the occurrence of a mannosylglycerate synthase potentially originating from a marine bacterium. To explain the observations on genome structure and gene content, we propose an evolutionary scenario involving an ancestral red alga that was driven by early ecological forces to lose genes, introns, and intergenetic DNA; this loss was followed by an expansion of genome size as a consequence of activity of transposable elements. %B Proceedings of the National Academy of Sciences %V 110 %P 5247–5252 %G eng %U http://www.pnas.org/content/110/13/5247.abstract %R 10.1073/pnas.1221259110 %0 Journal Article %J The ISME Journal %D 2013 %T Genomic island genes in a coastal marine Synechococcus strain confer enhanced tolerance to copper and oxidative stress %A Stuart, Rhona K. %A Brahamsha, Bianca %A Busby, Kayla %A Palenik, Brian %K RCC1086 %X Highly variable regions called genomic islands are found in the genomes of marine picocyanobacteria, and have been predicted to be involved in niche adaptation and the ecological success of these microbes. These picocyanobacteria are typically highly sensitive to copper stress and thus, increased copper tolerance could confer a selective advantage under some conditions seen in the marine environment. Through targeted gene inactivation of genomic island genes that were known to be upregulated in response to copper stress in Synechococcus sp. strain CC9311, we found two genes (sync_1495 and sync_1217) conferred tolerance to both methyl viologen and copper stress in culture. The prevalence of one gene, sync_1495, was then investigated in natural samples, and had a predictable temporal variability in abundance at a coastal monitoring site with higher abundance in winter months. Together, this shows that genomic island genes can confer an adaptive advantage to specific stresses in marine Synechococcus, and may help structure their population diversity. %B The ISME Journal %V 7 %P 1139–1149 %G eng %U http://www.nature.com/articles/ismej2012175 %R 10.1038/ismej.2012.175 %0 Journal Article %J Protist %D 2013 %T Morphology, genome plasticity, and phylogeny in the genus ostreococcus reveal a cryptic species, o. mediterraneus sp. nov. (mamiellales, mamiellophyceae) %A Subirana, Lucie %A Péquin, Bérangère %A Michely, Stéphanie %A Escande, Marie-Line %A Meilland, Julie %A Derelle, Evelyne %A Marin, Birger %A Piganeau, Gwenael %A Desdevises, Yves %A Moreau, Hervé %A Grimsley, Nigel H %K barcode %K Chromosome %K culture %K ITS2 %K karyotype %K picoeukaryote %K rcc %K RCC1112 %K RCC1114 %K RCC1117 %K RCC143 %K RCC1620 %K RCC1621 %K RCC1623 %K RCC1624 %K RCC2572 %K RCC2573 %K RCC2574 %K RCC2575 %K RCC2577 %K RCC2578 %K RCC2579 %K RCC2582 %K RCC2583 %K RCC2584 %K RCC2585 %K RCC2587 %K RCC2590 %K RCC344 %K RCC356 %K RCC393 %K rcc501 %K RCC745 %K RCC809 %K ribosomal gene %X Coastal marine waters in many regions worldwide support abundant populations of extremely small (1-3 ??m diameter) unicellular eukaryotic green algae, dominant taxa including several species in the class Mamiellophyceae. Their diminutive size conceals surprising levels of genetic diversity and defies classical species' descriptions. We present a detailed analysis within the genus Ostreococcus and show that morphological characteristics cannot be used to describe diversity within this group. Karyotypic analyses of the best-characterized species O. tauri show it to carry two chromosomes that vary in size between individual clonal lines, probably an evolutionarily ancient feature that emerged before species' divergences within the Mamiellales. By using a culturing technique specifically adapted to members of the genus Ostreococcus, we purified ¿30 clonal lines of a new species, Ostreococcus mediterraneus sp. nov., previously known as Ostreococcus clade D, that has been overlooked in several studies based on PCR-amplification of genetic markers from environment-extracted DNA. Phylogenetic analyses of the S-adenosylmethionine synthetase gene, and of the complete small subunit ribosomal RNA gene, including detailed comparisons of predicted ITS2 (internal transcribed spacer 2) secondary structures, clearly support that this is a separate species. In addition, karyotypic analyses reveal that the chromosomal location of its ribosomal RNA gene cluster differs from other Ostreococcus clades. %B Protist %V 164 %P 643–659 %G eng %U http://www.sciencedirect.com/science/article/pii/S1434461013000497 %R 10.1016/j.protis.2013.06.002 %0 Journal Article %J Genome Biology and Evolution %D 2013 %T Organellar inheritance in the green lineage: Insights from ostreococcus tauri %A Blanc-Mathieu, Romain %A Sanchez-Ferandin, Sophie %A Eyre-Walker, Adam %A Piganeau, Gwenael %K rcc %K RCC1108 %K RCC1110 %K RCC1112 %K RCC1114 %K RCC1115 %K RCC1116 %K RCC1117 %K RCC1118 %K RCC1123 %K RCC1558 %K RCC1559 %K RCC1561 %K RCC745 %X Along the green lineage (Chlorophyta and Streptophyta), mitochondria and chloroplast are mainly uniparentally transmitted and their evolution is thus clonal. The mode of organellar inheritance in their ancestor is less certain. The inability to make clear phylogenetic inference is partly due to a lack of information for deep branching organisms in this lineage. Here, we investigate organellar evolution in the early branching green alga Ostreococcus tauri using population genomics data from the complete mitochondrial and chloroplast genomes. The haplotype structure is consistent with clonal evolution in mitochondria, while we find evidence for recombination in the chloroplast genome. The number of recombination events in the genealogy of the chloroplast suggests that recombination, and thus biparental inheritance, is not rare. Consistent with the evidence of recombination, we find that the ratio of the number of nonsynonymous to the synonymous polymorphisms per site is lower in chloroplast than in the mitochondria genome. We also find evidence for the segregation of two selfish genetic elements in the chloroplast. These results shed light on the role of recombination and the evolutionary history of organellar inheritance in the green lineage. %B Genome Biology and Evolution %V 5 %P 1503–1511 %G eng %U http://gbe.oxfordjournals.org/content/5/8/1503.abstract %R 10.1093/gbe/evt106 %0 Journal Article %J Proceedings of the National Academy of Sciences of the United States of America %D 2013 %T Phycoerythrin-specific bilin lyase–isomerase controls blue-green chromatic acclimation in marine Synechococcus %A Shukla, A %A Biswas, A %A Blot, N %A Partensky, F %A Karty, J A %A Hammad, L A %A Garczarek, L %A Gutu, A %A Schluchter, W M %A Kehoe, D M %K 2013 %K rcc %K SBR$_\textrmP$hyto$_\textrmP$PM %K sbr?hyto?app %B Proceedings of the National Academy of Sciences of the United States of America %V 109 %P 20136–20141 %G eng %R 10.1073/pnas.1211777109 %0 Journal Article %J Nucleic Acids Research %D 2013 %T The protist ribosomal reference database (PR2): a catalog of unicellular eukaryote small SubUnit rRNA sequences with curated taxonomy %A Guillou, Laure %A Bachar, Dipankar %A Audic, Stéphane %A Bass, David %A Berney, Cedric %A Bittner, Lucie %A Boutte, Christophe %A Burgaud, Gaetan %A de Vargas, Colomban %A Decelle, Johan %A del Campo, Javier %A Dolan, John %A Dunthorn, Micah %A Bente, Edvardsen %A Holzmann, Maria %A Kooistra, Wiebe H C F %A Lara, Enrique %A Lebescot, Noan %A Logares, Ramiro %A Mahé, Frédéric %A Massana, Ramon %A Montresor, Marina %A Morard, Raphael %A Not, Fabrice %A Pawlowski, Jan %A Probert, Ian %A Sauvadet, Anne-Laure %A Siano, Raffaele %A Stoeck, Thorsten %A Vaulot, Daniel %A Zimmermann, Pascal %A Christen, Richard %K 2013 %K rcc %K SBR$_\textrmP$hyto$_\textrmD$PO %K SBR$_\textrmP$hyto$_\textrmE$PPO %K sbr?hyto$_\textrmd$ipo %K sbr?hyto?ppo %B Nucleic Acids Research %V 41 %P D597–D604 %G eng %R 10.1093/nar/gks1160 %0 Journal Article %J Biogeosciences %D 2012 %T Diversity of cultured photosynthetic flagellates in the North East Pacific and Arctic Oceans in summer %A Balzano, Sergio %A Gourvil, Priscillia %A Siano, Raffaele %A Chanoine, Mélanie %A Marie, Dominique %A Lessard, Sylvie %A Sarno, Diana %A Vaulot, Daniel %K 2012 %K ASSEMBLE %K MACUMBA %K MALINA %K rcc %K SBR$_\textrmP$hyto$_\textrmD$PO %K sbr?hyto$_\textrmd$ipo %B Biogeosciences %V 9 %P 4553–4571 %G eng %R 10.5194/bg-9-4553-2012 %0 Journal Article %J PLoS ONE %D 2012 %T Evaluating the ribosomal internal transcribed spacer (ITS) as a candidate dinoflagellate barcode marker %A Stern, Rowena F %A Andersen, Robert A %A Jameson, Ian %A Küpper, Frithjof C %A Coffroth, Mary-Alice %A Vaulot, Daniel %A Gall, Florence Le %A Veron, Benoit %A Brand, Jerry J %A Skelton, Hayley %A Kasai, Fumai %A Lilly, Emily L %A Keeling, Patrick J %K 2012 %K ASSEMBLE %K Barcoding %K ITS %K rcc %K SBR$_\textrmP$hyto$_\textrmD$PO %K sbr?hyto$_\textrmd$ipo %B PLoS ONE %V 7 %P e42780 %G eng %U http://www.plosone.org/article/info%253Adoi%252F10.1371%252Fjournal.pone.0042780 %R 10.1371/journal.pone.0042780 %0 Journal Article %J Proceedings of the National Academy of Sciences of the United States of America %D 2012 %T An original mode of symbiosis in open ocean plankton %A Decelle, J %A Probert, I %A Bittner, L %A Desdevises, Y %A Colin, S %A de Vargas, C %A Gali, M %A Simo, R %A Not, F %K 2012 %K rcc %K SBR$_\textrmP$hyto$_\textrmE$PPO %K sbr?hyto?ppo %B Proceedings of the National Academy of Sciences of the United States of America %V 109 %P 18000–18005 %G eng %R 10.1073/pnas.1212303109 %0 Journal Article %J Environmental Microbiology %D 2012 %T Phosphate transporters in marine phytoplankton and their viruses: cross-domain commonalities in viral-host gene exchanges %A Monier, Adam %A Welsh, Rory M %A Gentemann, Chelle %A Weinstock, George %A Sodergren, Erica %A Armbrust, E Virginia %A Eisen, Jonathan A %A Worden, Alexandra Z %K Micromonas %K rcc %X Phosphate (PO4) is an important limiting nutrient in marine environments. Marine cyanobacteria scavenge PO4 using the high-affinity periplasmic phosphate binding protein PstS. The pstS gene has recently been identified in genomes of cyanobacterial viruses as well. Here, we analyse genes encoding transporters in genomes from viruses that infect eukaryotic phytoplankton. We identified inorganic PO4 transporter-encoding genes from the PHO4 superfamily in several virus genomes, along with other transporter-encoding genes. Homologues of the viral pho4 genes were also identified in genome sequences from the genera that these viruses infect. Genome sequences were available from host genera of all the phytoplankton viruses analysed except the host genus Bathycoccus. Pho4 was recovered from Bathycoccus by sequencing a targeted metagenome from an uncultured Atlantic Ocean population. Phylogenetic reconstruction showed that pho4 genes from pelagophytes, haptophytes and infecting viruses were more closely related to homologues in prasinophytes than to those in what, at the species level, are considered to be closer relatives (e.g. diatoms). We also identified PHO4 superfamily members in ocean metagenomes, including new metagenomes from the Pacific Ocean. The environmental sequences grouped with pelagophytes, haptophytes, prasinophytes and viruses as well as bacteria. The analyses suggest that multiple independent pho4 gene transfer events have occurred between marine viruses and both eukaryotic and bacterial hosts. Additionally, pho4 genes were identified in available genomes from viruses that infect marine eukaryotes but not those that infect terrestrial hosts. Commonalities in marine host-virus gene exchanges indicate that manipulation of host-PO4 uptake is an important adaptation for viral proliferation in marine systems. Our findings suggest that PO4-availability may not serve as a simple bottom-up control of marine phytoplankton. %B Environmental Microbiology %V 14 %P 162–176 %G eng %U http://dx.doi.org/10.1111/j.1462-2920.2011.02576.x %R 10.1111/j.1462-2920.2011.02576.x %0 Journal Article %J Environmental Microbiology %D 2011 %T Basin-scale distribution patterns of photosynthetic picoeukaryotes along an Atlantic Meridional Transect %A Kirkham, Amy R %A Jardillier, Ludwig E %A Tiganescu, Ana %A Pearman, John %A Zubkov, Mikhail V %A Scanlan, David J %K Micromonas %K rcc %X Summary Photosynthetic picoeukaryotes (PPEs) of a size ¡ 3 µm play a crucial role in oceanic primary production. However, little is known of the structure of the PPE community over large spatial scales. Here, we investigated the distribution of various PPE classes along an Atlantic Meridional Transect sampled in boreal autumn 2004 that encompasses a range of ocean provinces (gyres, upwelling, temperate regions), using dot blot hybridization technology targeting plastid 16S rRNA gene amplicons. Two algal classes, Prymnesiophyceae and Chrysophyceae, dominated the PPE community throughout the Atlantic Ocean, over a range of water masses presenting different trophic profiles. However, these classes showed strongly complementary distributions with Chrysophyceae dominating northern temperate waters, the southern gyre and equatorial regions, while prymnesiophytes dominated the northern gyre. Phylogenetic analyses using both plastid and nuclear rRNA genes revealed a high diversity among members of both classes, including sequences contained in lineages with no close cultured counterpart. Other PPE classes were less prevalent along the transect, with members of the Cryptophyceae, Pelagophyceae and Eustigmatophyceae essentially restricted to specific regions. Multivariate statistical analyses revealed strong relationships between the distribution patterns of some of these latter PPE classes and temperature, light intensity and nutrient concentrations. Cryptophyceae, for example, were mostly found in the upwelling region and associated with higher nutrient concentrations. However, the key classes of Prymnesiophyceae and Chrysophyceae were not strongly influenced by the variables measured. Although there appeared to be a positive relationship between Chrysophyceae distribution and light intensity, the complementary distributions of these classes could not be explained by the variables recorded and this requires further explanation. %B Environmental Microbiology %V 13 %P 975–990 %G eng %U http://dx.doi.org/10.1111/j.1462-2920.2010.02403.x %R 10.1111/j.1462-2920.2010.02403.x %0 Journal Article %J Marine Drugs %D 2011 %T Coccolithophores: Functional biodiversity, enzymes and bioprospecting %A Reid, Emma L %A Worthy, Charlotte A %A Probert, Ian %A Ali, Sohail T %A Love, John %A Napier, Johnathan %A Littlechild, Jenny A %A Somerfield, Paul J %A Allen, Michael J %K 2011 %K rcc %K SBR$_\textrmP$hyto$_\textrmE$PPO %B Marine Drugs %V 9 %P 586–602 %G eng %U http://www.mdpi.com/1660-3397/9/4/586/ %R 10.3390/md9040586 %0 Journal Article %J The ISME journal %D 2011 %T Global distribution patterns of distinct clades of the photosynthetic picoeukaryote Ostreococcus %A Demir-Hilton, Elif %A Sudek, Sebastian %A Cuvelier, Marie L %A Gentemann, Chelle L %A Zehr, Jonathan P %A Worden, Alexandra Z %K rcc %K RCC745 %B The ISME journal %V 5 %P 1095–1107 %G eng %U http://dx.doi.org/10.1038/ismej.2010.209 http://www.nature.com/ismej/journal/vaop/ncurrent/suppinfo/ismej2010209s1.html http://www.nature.com/ismej/journal/v5/n7/full/ismej2010209a.html %R 10.1038/ismej.2010.209 %0 Journal Article %J Plant Physiology %D 2011 %T Light history influences the response of the marine cyanobacterium Synechococcus sp. WH7803 to oxidative stress %A Blot, N %A Mella-Flores, D %A Six, C %A Lecorguille, G %A Boutte, C %A Peyrat, A %A Monnier, A %A Ratin, M %A Gourvil, P %A Campbell, D A %A Garczarek, L %K 2011 %K rcc %K SBR$_\textrmP$hyto$_\textrmP$PM %K sbr?hyto?app %X Marine Synechococcus undergo a wide range of environmental stressors, especially high and variable irradiance, which may induce oxidative stress through the generation of reactive oxygen species (ROS). While light and ROS could act synergistically on the impairment of photosynthesis, inducing photodamage and inhibiting photosystem II repair, acclimation to high irradiance is also thought to confer resistance to other stressors. To identify the respective roles of light and ROS in the photoinhibition process and detect a possible light-driven tolerance to oxidative stress, we compared the photophysiological and transcriptomic responses of Synechococcus sp. WH7803 acclimated to low (LL) or high light (HL) to oxidative stress, induced by hydrogen peroxide (H2O2) or methylviologen. While photosynthetic activity was much more affected in HL than in LL cells, only HL cells were able to recover growth and photosynthesis after addition of 25 microM H2O2. Depending upon light conditions and H2O2 concentration, the latter oxidizing agent induced photosystem II inactivation through both direct damages to the reaction centres and inhibition of its repair cycle. Although the global transcriptome response appeared similar in LL and HL cells, some processes were specifically induced in HL cells that seemingly helped them withstand oxidative stress, including enhancement of photoprotection and ROS detoxification, repair of ROS-driven damages and regulation of redox state. Detection of putative LexA binding sites allowed the identification of the putative LexA regulon, which was down-regulated in HL compared to LL cells, but up-regulated by oxidative stress under both growth irradiances. %B Plant Physiology %V 156 %P 1934–1954 %G eng %U http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=21670225 %0 Journal Article %J Proceedings of the National Academy of Sciences of the United States of America %D 2011 %T Niche of harmful alga Aureococcus anophagefferens revealed through ecogenomics %A Gobler, C J %A Berry, D L %A Dyhrman, S T %A Wilhelm, S W %A Salamov, A %A Lobanov, A V %A Zhang, Y %A Collier, J L %A Wurch, L L %A Kustka, A B %A Dill, B D %A Shah, M %A VerBerkmoes, N C %A Kuo, A %A Terry, A %A Pangilinan, J %A Lindquist, E A %A Lucas, S %A Paulsen, I T %A Hattenrath-Lehmann, T K %A Talmage, S C %A Walker, E A %A Koch, F %A Burson, A M %A Marcoval, M A %A Tang, Y Z %A LeCleir, G R %A Coyne, K J %A Berg, G M %A Bertrand, E M %A Saito, M A %A Gladyshev, V N %A Grigoriev, I V %K brown-tide blooms %K comparative genomics %K eutrophication %K evolution %K genome %K genomics %K long-island %K marine-phytoplankton %K multidrug %K proteins %K proteome %K rcc %K repeat %K responses %K san-francisco bay %K signal-transduction %K transporters %X Harmful algal blooms (HABs) cause significant economic and ecological damage worldwide. Despite considerable efforts, a comprehensive understanding of the factors that promote these blooms has been lacking, because the biochemical pathways that facilitate their dominance relative to other phytoplankton within specific environments have not been identified. Here, biogeochemical measurements showed that the harmful alga Aureococcus anophagefferens outcompeted co-occurring phytoplankton in estuaries with elevated levels of dissolved organic matter and turbidity and low levels of dissolved inorganic nitrogen. We subsequently sequenced the genome of A. anophagefferens and compared its gene complement with those of six competing phytoplankton species identified through metaproteomics. Using an ecogenomic approach, we specifically focused on gene sets that may facilitate dominance within the environmental conditions present during blooms. A. anophagefferens possesses a larger genome (56 Mbp) and has more genes involved in light harvesting, organic carbon and nitrogen use, and encoding selenium-and metal-requiring enzymes than competing phytoplankton. Genes for the synthesis of microbial deterrents likely permit the proliferation of this species, with reduced mortality losses during blooms. Collectively, these findings suggest that anthropogenic activities resulting in elevated levels of turbidity, organic matter, and metals have opened a niche within coastal ecosystems that ideally suits the unique genetic capacity of A. anophagefferens and thus, has facilitated the proliferation of this and potentially other HABs. %B Proceedings of the National Academy of Sciences of the United States of America %V 108 %P 4352–4357 %G eng %R 10.1073/pnas.1016106108 %0 Journal Article %J The Plant Cell %D 2010 %T Characterization of a nitric oxide synthase from the plant kingdom: NO generation from the green alga Ostreococcus tauri is light irradiance and growth phase dependent %A Foresi, N %A Correa-Aragunde, N %A Parisi, G %A Calo, G %A Salerno, G %A Lamattina, L %K *Light %K Amino Acid Sequence %K Animals %K Base Sequence %K Chlorophyta/*enzymology/*growth & development/phys %K Humans %K Isoenzymes/chemistry/genetics/metabolism %K Models %K Molecular %K Molecular Sequence Data %K Nitric Oxide Synthase/chemistry/genetics/*metaboli %K Nitric Oxide/*biosynthesis %K phylogeny %K Plant Proteins/genetics/*metabolism %K Protein Structure %K rcc %K RCC745 %K Sequence Alignment %K Tertiary %X The search for a nitric oxide synthase (NOS) sequence in the plant kingdom yielded two sequences from the recently published genomes of two green algae species of the Ostreococcus genus, O. tauri and O. lucimarinus. In this study, we characterized the sequence, protein structure, phylogeny, biochemistry, and expression of NOS from O. tauri. The amino acid sequence of O. tauri NOS was found to be 45% similar to that of human NOS. Folding assignment methods showed that O. tauri NOS can fold as the human endothelial NOS isoform. Phylogenetic analysis revealed that O. tauri NOS clusters together with putative NOS sequences of a Synechoccocus sp strain and Physarum polycephalum. This cluster appears as an outgroup of NOS representatives from metazoa. Purified recombinant O. tauri NOS has a K(m) for the substrate l-Arg of 12 +/- 5 muM. Escherichia coli cells expressing recombinant O. tauri NOS have increased levels of NO and cell viability. O. tauri cultures in the exponential growth phase produce 3-fold more NOS-dependent NO than do those in the stationary phase. In O. tauri, NO production increases in high intensity light irradiation and upon addition of l-Arg, suggesting a link between NOS activity and microalgal physiology. %B The Plant Cell %V 22 %P 3816–3830 %G eng %U http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=21119059 %R 10.1105/tpc.109.073510 %0 Journal Article %J Marine Ecology-Progress Series %D 2010 %T Dimethylsulphoniopropionate (DMSP), DMSP-lyase activity (DLA) and dimethylsulphide (DMS) in 10 species of coccolithophore %A Franklin, D J %A Steinke, M %A Young, J %A Probert, I %A Malin, G %K 2010 %K rcc %K SBR$_\textrmP$hyto$_\textrmE$PPO %X We investigated dimethylsulphoniopropionate (DMSP) quota (pg DMSP cell(-1)), intracellular DMSP concentration (mM), in vitro and in vivo DMSP-lyase activity (DLA) and dimethylsulphide (DMS) concentration in batch cultures of 10 species of coccolithophore. Species were chosen to span the phylogenetic and size range that exists within the coccolithophores. Our overall objective was to examine if Emiliania huxleyi, considered a 'model' coccolithophore species, is representative in terms of DMSP, DLA and DMS, because other coccolithophores contribute substantially to phyto-plankton biomass and carbon fluxes in temperate and tropical waters. DMSP was found in all species, and DMSP quotas correlated significantly with cell volume, reflecting the fundamental physiological role of DMSP as a compatible solute in this group. This DMSP quota-cell volume relationship can be used to calculate the relative contribution of different species to total DMSP. Lowered nutrient availability (batch growth at a 10-fold lower nutrient concentration) did not significantly affect DMSP quota. In contrast to DMSP, DLA and DMS concentration were variable between the subset of species investigated. Coccolithophore DLA is known only in E. huxleyi and Gephyrocapsa oceanica, and we found DLA to be restricted to these closely related species. If DLA is restricted to a subset of coccolithophores, then those species are more likely to emit DMS directly in the sea. Our results indicate that in ecosystems where coccolithophores form stable populations, species other than E. huxleyi can make significant contributions to the particulate DMSP pool and hence to the amount of DMSP potentially available to the microbial loop. %B Marine Ecology-Progress Series %V 410 %P 13–23 %G eng %R 10.3354/meps08596 %0 Journal Article %J Journal of Phycology %D 2010 %T Dna Barcoding of Chlorarachniophytes Using Nucleomorph Its Sequences1 %A Gile, Gillian H. %A Stern, Rowena F. %A James, Erick R. %A Keeling, Patrick J. %K Bigelowiella %K Chlorarachnion %K culture collections %K Gymnochlora %K internal transcribed spacer %K Lotharella %K Norrisiella %K Partenskyella %K RCC337 %K RCC375 %K RCC376 %K RCC435 %K RCC530 %K RCC531 %K RCC623 %K RCC626 %X Chlorarachniophytes are a small group of marine photosynthetic protists. They are best known as examples of an intermediate stage of secondary endosymbiosis: their plastids are derived from green algae and retain a highly reduced nucleus, called a nucleomorph, between the inner and outer pairs of membranes. Chlorarachniophytes can be challenging to identify to the species level, due to their small size, complex life cycles, and the fact that even genus-level diagnostic morphological characters are observable only by EM. Few species have been formally described, and many available culture collection strains remain unnamed. To alleviate this difficulty, we have developed a barcoding system for rapid and accurate identification of chlorarachniophyte species in culture, based on the internal transcribed spacer (ITS) region of the nucleomorph rRNA cistron. Although this is a multicopy locus, encoded in both subtelomeric regions of each chromosome, interlocus variability is low due to gene conversion by homologous recombination in this region. Here, we present barcode sequences for 39 cultured strains of chlorarachniophytes (>80% of currently available strains). Based on barcode data, other published molecular data, and information from culture records, we were able to recommend names for 21 out of the 24 unidentified, partially identified, or misidentified chlorarachniophyte strains in culture. Most strains could be assigned to previously described species, but at least two to as many as five new species may be present among cultured strains. %B Journal of Phycology %V 46 %P 743–750 %G eng %U http://onlinelibrary.wiley.com/doi/abs/10.1111/j.1529-8817.2010.00851.x %R 10.1111/j.1529-8817.2010.00851.x %0 Journal Article %J The ISME journal %D 2010 %T A new chlorophyll d -containing cyanobacterium : evidence for niche adaptation in the genus Acaryochloris %A Mohr, Remus %A Schliep, Martin %A Kurz, Thorsten %A Maldener, Iris %A Adams, David G %A Larkum, Anthony D W %A Chen, Min %A Hess, Wolfgang R %K acaryochloris %K chlorophyll d %K coral reef %K cyanobacteria %K microbial diversity %K overview %K rcc %K RCC1983 %X Chlorophyll d is a photosynthetic pigment that, based on chemical analyses, has only recently been recognized to be widespread in oceanic and lacustrine environments. However, the diversity of organisms harbouring this pigment is not known. Until now, the unicellular cyanobacterium Acaryochloris marina is the only characterized organism that uses chlorophyll d as a major photopigment. In this study we describe a new cyanobacterium possessing a high amount of chlorophyll d, which was isolated from waters around Heron Island, Great Barrier Reef (231 260 31.200 S, 1511 540 50.400 E). The 16S ribosomal RNA is 2% divergent from the two previously described isolates of A. marina, which were isolated from waters around the Palau islands (Pacific Ocean) and the Salton Sea lake (California), suggesting that it belongs to a different clade within the genus Acaryochloris. An overview sequence analysis of its genome based on Illumina technology yielded 871 contigs with an accumulated length of 8 371965nt. Their analysis revealed typical features associated with Acaryochloris, such as an extended gene family for chlorophyll-binding proteins. However, compared with A. marina MBIC11017, distinct genetic, morphological and physiological differences were observed. Light saturation is reached at lower light intensities, Chl d/a ratios are less variable with light intensity and the phycobiliprotein phycocyanin is lacking, suggesting that cyanobacteria of the genus Acaryochloris occur in distinct ecotypes. These data characterize Acaryochloris as a niche-adapted cyanobacterium and show that more rigorous attempts are worthwhile to isolate, cultivate and analyse chlorophyll d-containing cyanobacteria for understanding the ecophysiology of these organisms. The %B The ISME journal %P 1456–1469 %G eng %R 10.1038/ismej.2010.67 %0 Journal Article %J Protist %D 2010 %T Pelagodinium gen. nov. and P. beii comb. nov., a dinoflagellate symbiont of planktonic foraminifera %A Siano, R %A Montresor, M %A Probert, I %A Not, F %A de Vargas, C %K 2010 %K ASSEMBLE %K rcc %K rcc1491 %K SBR$_\textrmP$hyto$_\textrmE$PPO %K sbr?hyto?ppo %X The taxonomic status of the free-living stage of the dinoflagellate Gymnodinium béii, symbiont of the foraminifer Orbulina universa, was reassessed on the basis of detailed morpho-genetic analyses. Electron microscopy observations revealed previously undescribed morphological features of the cell that are important for species recognition. The presence of a single elongated apical vesicle (EAV) ornamented with a row of small knobs, absent in species of the genus Gymnodinium, calls into question the current taxonomic position of the symbiont. The presence of a type E extraplastidial eyespot, the arrangement of the amphiesmal vesicles in series and the absence of trichocysts confirm the affiliation with other symbiotic dinoflagellates and certain genetically related non-symbiotic genera, all belonging to the order Suessiales. The arrangement of the series of vesicles of the analyzed strain is unique within the Suessiales, and the ultrastructure of the pyrenoid is different from other symbiotic dinoflagellates. A large subunit (LSU) rDNA phylogenetic analysis confirmed that the analyzed pelagic symbiont clusters in an independent, well-supported clade within the Suessiales with other sequences of symbiotic dinoflagellates extracted from planktonic foraminifera. Hence a novel genus, Pelagodinium gen. nov., is erected for this pelagic, symbiotic dinoflagellate, and Gymnodinium béii is reclassified as Pelagodinium béii. %B Protist %V 161 %P 385–399 %G eng %R 10.1016/j.protis.2010.01.002 %0 Journal Article %J BMC Evolutionary Biology %D 2010 %T A phylogenetic mosaic plastid proteome and unusual plastid-targeting signals in the green-colored dinoflagellate Lepidodinium chlorophorum %A Minge, M A %A Shalchian-Tabrizi, K %A Torresen, O K %A Takishita, K %A Probert, I %A Inagaki, Y %A Klaveness, D %A Jakobsen, K S %K 2010 %K rcc %K SBR$_\textrmP$hyto$_\textrmE$PPO %X Background: Plastid replacements through secondary endosymbioses include massive transfer of genes from the endosymbiont to the host nucleus and require a new targeting system to enable transport of the plastid-targeted proteins across 3-4 plastid membranes. The dinoflagellates are the only eukaryotic lineage that has been shown to have undergone several plastid replacement events, and this group is thus highly relevant for studying the processes involved in plastid evolution. In this study, we analyzed the phylogenetic origin and N-terminal extensions of plastid-targeted proteins from Lepidodinium chlorophorum, a member of the only dinoflagellate genus that harbors a green secondary plastid rather than the red algal-derived, peridinin-containing plastid usually found in photosynthetic dinoflagellates. Results: We sequenced 4,746 randomly picked clones from a L. chlorophorum cDNA library. 22 of the assembled genes were identified as genes encoding proteins functioning in plastids. Some of these were of green algal origin. This confirms that genes have been transferred from the plastid to the host nucleus of L. chlorophorum and indicates that the plastid is fully integrated as an organelle in the host. Other nuclear-encoded plastid-targeted protein genes, however, are clearly not of green algal origin, but have been derived from a number of different algal groups, including dinoflagellates, streptophytes, heterokonts, and red algae. The characteristics of N-terminal plastid-targeting peptides of all of these genes are substantially different from those found in peridinin-containing dinoflagellates and green algae. Conclusions: L. chlorophorum expresses plastid-targeted proteins with a range of different origins, which probably arose through endosymbiotic gene transfer (EGT) and horizontal gene transfer (HGT). The N-terminal extension of the genes is different from the extensions found in green alga and other dinoflagellates (peridinin- and haptophyte plastids). These modifications have likely enabled the mosaic proteome of L. chlorophorum. %B BMC Evolutionary Biology %V 10 %P 191 %G eng %R 10.1186/1471-2148-10-191 %0 Journal Article %J The ISME Journal %D 2010 %T Significant CO2 fixation by small prymnesiophytes in the subtropical and tropical northeast Atlantic Ocean %A Jardillier, Ludwig %A Zubkov, Mikhail V %A Pearman, John %A Scanlan, David J %K Micromonas %K rcc %B The ISME Journal %V 4 %P 1180–1192 %G eng %U http://dx.doi.org/10.1038/ismej.2010.36 http://www.nature.com/ismej/journal/vaop/ncurrent/suppinfo/ismej201036s1.html %R 10.1038/ismej.2010.36 %0 Conference Paper %B Third international barcode of life conference %D 2009 %T DNA barcoding of protists in culture collections %A Meusnier, Isabelle %A Andersen, Robert A %A Stern, Rowena %A Bertrand, C %A Kuepper, Frithjof %A Brand, Jerry %A Friedl, Thomas %A Blackburn, Susan %A Dinh, Donna %A Acreman, Judy %A Sedláček, Ivo %A Přibyl, Pavel %A Jutson, Maria %A Phang, Siew Moi %A Melkonian, M %A Karpov, S %A Hajibabaei, Mehrdad %K ? No DOI found %K rcc %K SBR$_\textrmP$hyto$_\textrmD$PO %B Third international barcode of life conference %C Mexico City %G eng %0 Journal Article %J Microbiology and Molecular Biology Reviews %D 2009 %T Ecological genomics of marine picocyanobacteria %A Scanlan, D J %A Ostrowski, M %A Mazard, S %A Dufresne, A %A Garczarek, L %A Hess, W R %A Post, A F %A Hagemann, M %A Paulsen, I %A Partensky, F %K 2009 %K rcc %K SBR$_\textrmP$hyto$_\textrmP$PM %K sbr?hyto?app %B Microbiology and Molecular Biology Reviews %V 73 %P 249–299 %G eng %R 10.1128/MMBR.00035-08 %0 Journal Article %J Science %D 2009 %T Green evolution and dynamic adaptations revealed by genomes of the marine picoeukaryotes Micromonas %A Worden, A Z %A Lee, J.- H %A Mock, T %A Rouzé, P %A Simmons, M P %A Aerts, A L %A Allen, A E %A Cuvelier, M L %A Derelle, E %A Everett, M V %A Foulon, E %A Grimwood, J %A Gundlach, H %A Henrissat, B %A Napoli, C %A McDonald, S M %A Parker, M S %A Rombauts, S %A Salamov, A %A Von Dassow, P %A Badger, J H %A Coutinho, P M %A Demir, E %A Dubchak, I %A Gentemann, C %A Eikrem, W %A Gready, J E %A John, U %A Lanier, W %A Lindquist, E A %A Lucas, S %A Mayer, K F X %A Moreau, H %A Not, F %A Otillar, R %A Panaud, O %A Pangilinan, J %A Paulsen, I %A Piegu, B %A Poliakov, A %A Robbens, S %A Schmutz, J %A Toulza, E %A Wyss, T %A Zelensky, A %A Zhou, K %A Armbrust, E V %A Bhattacharya, D %A Goodenough, U W %A Van de Peer, Y %A Grigoriev, I V %K rcc %K RCC299 %K RCC827 %K SBR$_\textrmP$hyto$_\textrmD$PO %K SBR$_\textrmP$hyto$_\textrmE$PPO %X The photosynthetic picoeukaryote Micromonas thrives from tropical to polar marine ecosystems and belongs to an anciently diverged sister clade to land plants. We sequenced genomes from two Micromonas isolates (22 Mb, CCMP1545; 21 Mb, RCC299) and the results improve understanding of their ecology and green-lineage evolution. Despite high 18S rDNA sequence identity, only 90% of their predicted genes were shared. Novel intronic repeat elements in CCMP1545, otherwise found only in metagenomic data, and unique riboswitch arrangements emphasized their independent evolutionary paths. Phylogenomic profiles revealed putative ancestral features, but also indicated selection/acquisition processes are actively shaping a ‘unique' gene pool in each differently than ‘core' genes. Current climate-change trajectories are predicted to produce conditions favoring picophytoplankton, making Micromonas potential indicators of biological change in ocean ecosystems. %B Science %V 324 %P 268–272 %G eng %R 10.1126/science.1167222 %0 Journal Article %J Nature %D 2009 %T Photosystem I gene cassettes are present in marine virus genomes %A Sharon, Itai %A Alperovitch, Ariella %A Rohwer, Forest %A Haynes, Matthew %A Glaser, Fabian %A Atamna-Ismaeel, Nof %A Pinter, Ron Y %A Partensky, Frédéric %A Koonin, Eugene V %A Wolf, Yuri I %A Nelson, Nathan %A Béjà, Oded %K RCC307 %K SBR$_\textrmP$hyto$_\textrmP$PM %B Nature %V 461 %P 258–262 %G eng %U http://dx.doi.org/10.1038/nature08284 http://www.nature.com/nature/journal/v461/n7261/suppinfo/nature08284_S1.html %R 10.1038/nature08284 %0 Journal Article %J Plant Physiology %D 2009 %T Photosystem II and pigment dynamics among ecotypes of the green alga Ostreococcus %A Six, C %A Sherrard, R %A Lionard, M %A Roy, S %A Campbell, D A %K rcc %K RCC809 %K SBR$_\textrmP$hyto$_\textrmP$PM %X We investigated the photophysiological response of three ecotypes of the picophytoplankter Ostreococcus and a larger prasinophyte Pyramimonas obovata to a sudden increase in light irradiance. The deepwater Ostreococcus sp. RCC809 showed very high susceptibility to primary photoinactivation, likely a consequence of high oxidative stress, which may relate to the recently noted plastid terminal oxidase activity in this strain. The three Ostreococcus ecotypes were all able of deploying modulation of photosystem II repair cycle in order to cope with the light increase, but the effective clearance of photoinactivated D1 protein appeared to be slower in the deep water Ostreococcus sp. RCC809, suggesting that this step is rate-limiting in the photosystem II repair cycle in this strain. The deepwater Ostreococcus moreover accumulated lutein and showed substantial use of the xanthophyll cycle under light stress, demonstrating its high sensitivity to light fluctuations. The sustained component of the non-photochemical quenching of fluorescence correlated well with the xanthophyll de-epoxidation activity. Comparisons with the larger prasinophyte Pyramimonas obovata suggest that the photophysiology of Ostreococcus ecotypes requires high photosystem II repair rates to counter a high susceptibility to photoinactivation, consistent with low pigment package effects in their minute-sized cells. %B Plant Physiology %V 151 %P 379–390 %G eng %R 10.1104/pp.109.140566 %0 Journal Article %J Limnology and Oceanography %D 2008 %T Contrasting photoacclimation strategies in ecotypes of the eukayotic picoplankter ¡i¿Ostreococcus¡/i¿ %A Six, C %A Finkel, Z V %A Rodriguez, F %A Marie, D %A Partensky, F %A Campbell, D A %K 2008 %K rcc %K SBR$_\textrmP$hyto$_\textrmD$PO %K sbr?hyto$_\textrmd$ipo %K sbr?hyto?app %X Ostreococcus, the smallest known marine picoeukaryote, includes low- and high-light ecotypes. To determine the basis for niche partitioning between Ostreococcus sp. RCC809, isolated from the bottom of the tropical Atlantic euphotic zone, and the lagoon strain Ostreococcus tauri, we studied their photophysiologies under growth irradiances from 15 mmol photons m22 s21 to 800 mmol photons m22 s21 with a common nutrient replete regime. With increasing growth irradiance, both strains down-regulated cellular chlorophyll a and chlorophyll b (Chl a and Chl b) content, increased xanthophyll de-epoxidation correlated with nonphotochemical excitation quenching, and accumulated lutein. Ribulose-1,5-bisphosphate carboxylase/oxygenase content remained fairly stable. Under low-growth irradiances of 15–80 mmol photons m22 s21, O. sp. RCC809 had equivalent or slightly higher growth rates, lower Chl a, a higher Chl b : Chl a ratio, and a larger photosystem II (PSII) antenna than O. tauri. O. tauri was more phenotypically plastic in response to growth irradiance, with a larger dynamic range in growth rate, Chl a, photosystem cell content, and cellular absorption cross-section of PSII. Estimating the amino acid and nitrogen costs for photoacclimation showed that the deep-sea oceanic O. sp. RCC809 relies largely on lower nitrogen cost changes in PSII antenna size to achieve a limited range of s-type light acclimation. O. sp. RCC809, however, suffers photoinhibition under higher light. This limited capacity for photoacclimation is compatible with the stable low-light and nutrient conditions at the base of the euphotic layer of the tropical Atlantic Ocean. In the more variable, high-nutrient, lagoon environment, O. tauri can afford to use a higher cost n-type acclimation of photosystem contents to exploit a wider range of light. %B Limnology and Oceanography %V 53 %P 255–265 %G eng %R 10.4319/lo.2008.53.1.0255 %0 Journal Article %J Environmental Microbiology %D 2008 %T Ecological niche partitioning in the picoplanktonic green alga Micromonas pusilla: evidence from environmental surveys using phylogenetic probes %A Foulon, E %A Not, F %A Jalabert, F %A Cariou, T %A Massana, R %A Simon, N %K 2008 %K rcc %K SBR$_\textrmP$hyto$_\textrmD$PO %K sbr?hyto$_\textrmd$ipo %B Environmental Microbiology %V 10 %P 2433–2443 %G eng %R 10.1111/j.1462-2920.2008.01673.x %0 Journal Article %J Journal of Plant Research %D 2008 %T Genome analysis and its significance in four unicellular algae, Cyanidioshyzon merolae, Ostreococcus tauri, Chlamydomonas reinhardtii, and Thalassiosira pseudonana %A Misumi, O %A Yoshida, Y %A Nishida, K %A Fujiwara, T %A Sakajiri, T %A Hirooka, S %A Nishimura, Y %A Kuroiwa, T %K rcc %X Algae play a more important role than land plants in the maintenance of the global environment and productivity. Progress in genome analyses of these organisms means that we can now obtain information on algal genomes, global annotation and gene expression. The full genome information for several algae has already been analyzed. Whole genomes of the red alga Cyanidioshyzon merolae, the green algae Ostreococcus tauri and Chlamydomonas reinhardtii, and the diatom Thalassiosira pseudonana have been sequenced. Genome composition and the features of cells among the four algae were compared. Each alga maintains basic genes as photosynthetic eukaryotes and possesses additional gene groups to represent their particular characteristics. This review discusses and introduces the latest research that makes the best use of the particular features of each organism and the significance of genome analysis to study biological phenomena. In particular, examples of post-genome studies of organelle multiplication in C. merolae based on analyzed genome information are presented. %B Journal of Plant Research %V 121 %P 3–17 %G eng %U http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=18074102 %0 Journal Article %J New Phytologist %D 2008 %T New tools for labeling silica in living diatoms %A Descles, J %A Vartanian, M %A El Harrak, A %A Quinet, M %A Bremond, N %A Sapriel, G %A Bibette, J %A Lopez, P J %K 3D-imaging %K BACILLARIOPHYCEAE %K BIOLOGY %K biomineralization %K DEPOSITION %K diatoms %K exocytosis %K FLUORESCENT %K nanopattern %K pH %K phaeodactylum-tricornutum %K PLANTS %K rcc %K THALASSIOSIRA-PSEUDONANA %K ultrastructure %K VESICLE %X Silicon biomineralization is a widespread mechanism found in several kingdoms that concerns both unicellular and multicellular organisms. As a result of genomic and molecular tools, diatoms have emerged as a good model for biomineralization studies and have provided most of the current knowledge on this process. However, the number of techniques available to study its dynamics at the cellular level is still rather limited. Here, new probes were developed specifically to label the pre-existing or the newly synthesized silica frustule of several diatoms species. It is shown that the LysoTracker Yellow HCK-123, which can be used to visualize silica frustules with common filter sets, presents an enhanced signal-to-noise ratio and allows details of the frustules to be imaged without of the use of ionophores. It is also demonstrated that methoxysilane derivatives can be coupled to fluorescein-5-isothiocyanate (FITC) to preferentially label the silica components of living cells. The coupling of labeling procedures might help to address the challenging question of the process of frustule exocytosis. %B New Phytologist %V 177 %P 822–829 %G eng %R 10.1111/j.1469-8137.2007.02303.x %0 Journal Article %J Nature %D 2008 %T The Phaeodactylum genome reveals the evolutionary history of diatom genomes %A Bowler, Chris %A Allen, Andrew E %A Badger, Jonathan H %A Grimwood, Jane %A Jabbari, Kamel %A Kuo, Alan %A Maheswari, Uma %A Martens, Cindy %A Maumus, Florian %A Otillar, Robert P %A Rayko, Edda %A Salamov, Asaf %A Vandepoele, Klaas %A Beszteri, Bank %A Gruber, Ansgar %A Heijde, Marc %A Katinka, Michael %A Mock, Thomas %A Valentin, Klaus %A Verret, Frederic %A Berges, John A %A Brownlee, Colin %A Cadoret, Jean-Paul %A Chiovitti, Anthony %A Choi, Chang Jae %A Coesel, Sacha %A De Martino, Alessandra %A Detter, J Chris %A Durkin, Colleen %A Falciatore, Angela %A Fournet, Jerome %A Haruta, Miyoshi %A Huysman, Marie J J %A Jenkins, Bethany D %A Jiroutova, Katerina %A Jorgensen, Richard E %A Joubert, Yolaine %A Kaplan, Aaron %A Kroger, Nils %A Kroth, Peter G %A La Roche, Julie %A Lindquist, Erica %A Lommer, Markus %A Martin-Jezequel, Veronique %A Lopez, Pascal J %A Lucas, Susan %A Mangogna, Manuela %A McGinnis, Karen %A Medlin, Linda K %A Montsant, Anton %A Secq, Marie-Pierre Oudot-Le %A Napoli, Carolyn %A Obornik, Miroslav %A Parker, Micaela Schnitzler %A Petit, Jean-Louis %A Porcel, Betina M %A Poulsen, Nicole %A Robison, Matthew %A Rychlewski, Leszek %A Rynearson, Tatiana A %A Schmutz, Jeremy %A Shapiro, Harris %A Siaut, Magali %A Stanley, Michele %A Sussman, Michael R %A Taylor, Alison R %A Vardi, Assaf %A von Dassow, Peter %A Vyverman, Wim %A Willis, Anusuya %A Wyrwicz, Lucjan S %A Rokhsar, Daniel S %A Weissenbach, Jean %A Armbrust, E Virginia %A Green, Beverley R %A Van de Peer, Yves %A Grigoriev, Igor V %K 2008 %K rcc %K SBR$_\textrmP$hyto$_\textrmE$PPOdipo %K sbr?hyto?ppo %B Nature %V 456 %P 239–244 %G eng %U http://dx.doi.org/10.1038/nature07410 http://www.nature.com/nature/journal/v456/n7219/suppinfo/nature07410_S1.html %R 10.1038/nature07410 %0 Journal Article %J Genome Biology %D 2007 %T Diversity and evolution of phycobilisomes in marine Synechococcus spp. - a comparative genomics study %A Six, C %A Thomas, J.-C. %A Garczarek, L %A Ostrowski, M %A Dufresne, A %A Blot, N %A Scanlan, D J %A Partensky, F %K 2007 %K rcc %K SBR$_\textrmP$hyto %K sbr?hyto?app %B Genome Biology %V 8 %P R259 %G eng %R 10.1186/gb-2007-8-12-r259 %0 Journal Article %J Genome Biology %D 2007 %T Evolutionary dynamics of eukaryotic selenoproteomes: large selenoproteomes may associate with aquatic life and small with terrestrial life %A Lobanov, A V %A Fomenko, D E %A Zhang, Y %A Sengupta, A %A Hatfield, D L %A Gladyshev, V N %K rcc %X BACKGROUND: Selenocysteine (Sec) is a selenium-containing amino acid that is co-translationally inserted into nascent polypeptides by recoding UGA codons. Selenoproteins occur in both eukaryotes and prokaryotes, but the selenoprotein content of organisms (selenoproteome) is highly variable and some organisms do not utilize Sec at all. RESULTS: We analyzed the selenoproteomes of several model eukaryotes and detected 26 and 29 selenoprotein genes in the green algae Ostreococcus tauri and Ostreococcus lucimarinus, respectively, five in the social amoebae Dictyostelium discoideum, three in the fly Drosophila pseudoobscura, and 16 in the diatom Thalassiosira pseudonana, including several new selenoproteins. Distinct selenoprotein patterns were verified by metabolic labeling of O. tauri and D. discoideum with 75Se. More than half of the selenoprotein families were shared by unicellular eukaryotes and mammals, consistent with their ancient origin. Further analyses identified massive, independent selenoprotein losses in land plants, fungi, nematodes, insects and some protists. Comparative analyses of selenoprotein-rich and -deficient organisms revealed that aquatic organisms generally have large selenoproteomes, whereas several groups of terrestrial organisms reduced their selenoproteomes through loss of selenoprotein genes and replacement of Sec with cysteine. CONCLUSION: Our data suggest many selenoproteins originated at the base of the eukaryotic domain and show that the environment plays an important role in selenoproteome evolution. In particular, aquatic organisms apparently retained and sometimes expanded their selenoproteomes, whereas the selenoproteomes of some terrestrial organisms were reduced or completely lost. These findings suggest a hypothesis that, with the exception of vertebrates, aquatic life supports selenium utilization, whereas terrestrial habitats lead to reduced use of this trace element due to an unknown environmental factor. %B Genome Biology %V 8 %P R198 %G eng %U http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17880704 %0 Journal Article %J PLoS genetics %D 2007 %T Patterns and implications of gene gain and loss in the evolution of Prochlorococcus %A Kettler, G %A Martiny, A C %A Huang, K %A Zucker, J %A Coleman, M L %A Rodrigue, S %A Chen, F %A Lapidus, A %A Ferriera, S %A Johnson, J %A Steglich, C %A Church, G %A Richardson, P %A Chisholm, S W %K rcc %B PLoS genetics %V 3 %P e231 %G eng %R 10.1371/journal.pgen.0030231 %0 Journal Article %J Journal of Phycology %D 2007 %T Photophysiological properties of the marine picoeukaryote Picochlorum RCC 237 (Trebouxiophyceae, Chlorophyta) %A Dimier, C %A Corato, F %A Saviello, G %A Brunet, C %K A FLUORESCENCE %K CHLAMYDOMONAS-REINHARDTII %K DIATOM PHAEODACTYLUM-TRICORNUTUM %K ENERGY-DISSIPATION %K fluctuating light %K fluorescence quantum yield %K MANTONIELLA-SQUAMATA %K nonphotochemical quenching of fluorescence %K photoacclimation %K PHOTOSYNTHETIC APPARATUS %K picoplankton %K POOL SIZE %K rcc %K VIOLAXANTHIN DE-EPOXIDASE %K Xanthophyll cycle %K XANTHOPHYLL-CYCLE %K zeaxanthin %X The photophysiological properties of strain RCC 237 belonging to the marine picoplanktonic genus Picochlorum, first described by Henley et al., were investigated under different photon flux densities (PFD), ranging from 40 to 400 mu mol photons. m(-2).s(-1), mainly focusing on the development of the xanthophyll cycle and its relationship with the nonphotochemical quenching of fluorescence (NPQ). The functioning of the xanthophyll cycle and its photoprotective role was investigated by applying a progressive increase of PFD and using dithiotreitol and norflurazon to block specific enzymatic reactions in order to study in depth the relationship between xanthophyll cycle and NPQ. These two processes were significantly related only during the gradually increasing light periods and not during stable light periods, where NPQ and zeaxanthin were decoupled. This result reveals that NPQ is a photoprotective process developed by algae only when cells are experiencing increasing PFD or in response to stressful light variations, for instance after a sudden light shift. Results showed that the photobiological properties of Picochlorum strain RCC 237 seem to be well related to the surface water characteristics, as it is able to maintain its photosynthetic characteristics under different PFDs and to quickly activate the xanthophyll cycle under high light. %B Journal of Phycology %V 43 %P 275–283 %G eng %R 10.1111/j.1529-8817.2007.00327.x %0 Journal Article %J Proceedings of the National Academy of Sciences of the United States of America %D 2007 %T The tiny eukaryote \textit{Ostreococcus provides genomic insights into the paradox of plankton speciation %A Palenik, B %A Grimwood, J %A Aerts, A %A Rouzé, P %A Salamov, A %A Putnam, N %A Dupont, C %A Jorgensen, R %A Derelle, E %A Rombauts, S %A Zhou, K %A Otillar, R %A Merchant, S S %A Podell, S %A Gaasterland, T %A Napoli, C %A Gendler, K %A Manuell, A %A Tai, V %A Vallon, O %A Piganeau, G %A Jancek, S %A Heijde, M %A Jabbari, K %A Bowler, C %A Lohr, M %A Robbens, S %A Werner, G %A Dubchak, I %A Pazour, G J %A Ren, Q %A Paulsen, I %A Delwiche, C %A Schmutz, J %A Rokhsar, D %A Van de Peer, Y %A Moreau, H %A Grigoriev, I V %K rcc %X The smallest known eukaryotes, at approximately 1-mum diameter, are Ostreococcus tauri and related species of marine phytoplankton. The genome of Ostreococcus lucimarinus has been completed and compared with that of O. tauri. This comparison reveals surprising differences across orthologous chromosomes in the two species from highly syntenic chromosomes in most cases to chromosomes with almost no similarity. Species divergence in these phytoplankton is occurring through multiple mechanisms acting differently on different chromosomes and likely including acquisition of new genes through horizontal gene transfer. We speculate that this latter process may be involved in altering the cell-surface characteristics of each species. In addition, the genome of O. lucimarinus provides insights into the unique metal metabolism of these organisms, which are predicted to have a large number of selenocysteine-containing proteins. Selenoenzymes are more catalytically active than similar enzymes lacking selenium, and thus the cell may require less of that protein. As reported here, selenoenzymes, novel fusion proteins, and loss of some major protein families including ones associated with chromatin are likely important adaptations for achieving a small cell size. %B Proceedings of the National Academy of Sciences of the United States of America %V 104 %P 7705–7710 %G eng %U http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17460045 %0 Journal Article %J Aquatic Microbial Ecology %D 2006 %T Analysis of photosynthetic picoeukaryote diversity at open ocean sites in the Arabian Sea using a PCR biased towards marine algal plastids %A Fuller, Nicholas J %A Campbell, Colin %A Allen, David J %A Pitt, Frances D %A Le Gall, F %A Vaulot, Daniel %A Scanlan, David J %K 2006 %K PICOCEAN %K PICODIV %K rcc %K SBR$_\textrmP$hyto$_\textrmD$PO %K sbr?hyto$_\textrmd$ipo %B Aquatic Microbial Ecology %V 43 %P 79–93 %G eng %R 10.3354/ame043079 %0 Journal Article %J Journal of Bacteriology %D 2006 %T Biochemical bases of Type IV chromatic adaptation in marine Synechococcus spp. %A Everroad, C %A Six, C %A Partensky, F %A Thomas, J C %A Holtzendorff, J %A Wood, A M %K 2006 %K rcc %K SBR$_\textrmP$hyto %K sbr?hyto?app %B Journal of Bacteriology %V 188 %P 3345–3356 %G eng %R 10.1128/JB.188.9.3345-3356.2006 %0 Journal Article %J Proceedings of the National Academy of Sciences of the United States of America %D 2006 %T Genome analysis of the smallest free-living eukaryote Ostreococcus tauri unveils many unique features %A Derelle, Evelyne %A Ferraz, Conchita %A Rombauts, Stephane %A Rouze, Pierre %A Worden, Alexandra Z %A Robbens, Steven %A Partensky, Frédéric %A Degroeve, Sven %A Echeynie, Sophie %A Cooke, Richard %A Saeys, Yvan %A Wuyts, Jan %A Jabbari, Kamel %A Bowler, Chris %A Panaud, Olivier %A Piegu, Benoit %A Ball, Steven G %A Ral, Jean-Philippe %A Bouget, François-Yves %A Piganeau, Gwenael %A De Baets, Bernard %A Picard, André %A Delseny, Michel %A Demaille, Jacques %A Van de Peer, Yves %A Moreau, Hervé %K rcc %K RCC745 %K SBR$_\textrmP$hyto %X The green lineage is reportedly 1,500 million years old, evolving shortly after the endosymbiosis event that gave rise to early photosynthetic eukaryotes. In this study, we unveil the complete genome sequence of an ancient member of this lineage, the unicellular green alga Ostreococcus tauri (Prasinophyceae). This cosmopolitan marine primary producer is the world's smallest free-living eukaryote known to date. Features likely reflecting optimization of environmentally relevant pathways, including resource acquisition, unusual photosynthesis apparatus, and genes potentially involved in C4 photosynthesis, were observed, as was downsizing of many gene families. Overall, the 12.56-Mb nuclear genome has an extremely high gene density, in part because of extensive reduction of intergenic regions and other forms of compaction such as gene fusion. However, the genome is structurally complex. It exhibits previously unobserved levels of heterogeneity for a eukaryote. Two chromosomes differ structurally from the other eighteen. Both have a significantly biased G+C content, and, remarkably, they contain the majority of transposable elements. Many chromosome 2 genes also have unique codon usage and splicing, but phylogenetic analysis and composition do not support alien gene origin. In contrast, most chromosome 19 genes show no similarity to green lineage genes and a large number of them are specialized in cell surface processes. Taken together, the complete genome sequence, unusual features, and downsized gene families, make O. tauri an ideal model system for research on eukaryotic genome evolution, including chromosome specialization and green lineage ancestry. %B Proceedings of the National Academy of Sciences of the United States of America %V 103 %P 11647–11652 %G eng %U http://www.pnas.org/cgi/content/abstract/103/31/11647 %R 10.1073/pnas.0604795103 %0 Journal Article %J Proceedings of the National Academy of Sciences of the United States of America %D 2006 %T Genome sequence of Synechococcus CC9311: Insights into adaptation to a coastal environment %A Palenik, Brian %A Ren, Qinghu %A Dupont, Chris L %A Myers, Garry S %A Heidelberg, John F %A Badger, Jonathan H %A Madupu, Ramana %A Nelson, William C %A Brinkac, Lauren M %A Dodson, Robert J %A Durkin, A Scott %A Daugherty, Sean C %A Sullivan, Stephen A %A Khouri, Hoda %A Mohamoud, Yasmin %A Halpin, Rebecca %A Paulsen, Ian T %K rcc %X Coastal aquatic environments are typically more highly productive and dynamic than open ocean ones. Despite these differences, cyanobacteria from the genus Synechococcus are important primary producers in both types of ecosystems. We have found that the genome of a coastal cyanobacterium, Synechococcus sp. strain CC9311, has significant differences from an open ocean strain, Synechococcus sp. strain WH8102, and these are consistent with the differences between their respective environments. CC9311 has a greater capacity to sense and respond to changes in its (coastal) environment. It has a much larger capacity to transport, store, use, or export metals, especially iron and copper. In contrast, phosphate acquisition seems less important, consistent with the higher concentration of phosphate in coastal environments. CC9311 is predicted to have differences in its outer membrane lipopolysaccharide, and this may be characteristic of the speciation of some cyanobacterial groups. In addition, the types of potentially horizontally transferred genes are markedly different between the coastal and open ocean genomes and suggest a more prominent role for phages in horizontal gene transfer in oligotrophic environments. %B Proceedings of the National Academy of Sciences of the United States of America %V 103 %P 13555–13559 %G eng %U http://www.pnas.org/cgi/content/abstract/103/36/13555 %R 10.1073/pnas.0602963103 %0 Journal Article %J Proceedings of the National Academy of Sciences %D 2006 %T Genome sequence of Synechococcus CC9311: Insights into adaptation to a coastal environment %A Palenik, Brian %A Ren, Qinghu %A Dupont, Chris L. %A Myers, Garry S. %A Heidelberg, John F. %A Badger, Jonathan H. %A Madupu, Ramana %A Nelson, William C. %A Brinkac, Lauren M. %A Dodson, Robert J. %A Durkin, A. Scott %A Daugherty, Sean C. %A Sullivan, Stephen A. %A Khouri, Hoda %A Mohamoud, Yasmin %A Halpin, Rebecca %A Paulsen, Ian T. %K cyanobacteria %K genomics %K Marine %K RCC1086 %X Coastal aquatic environments are typically more highly productive and dynamic than open ocean ones. Despite these differences, cyanobacteria from the genus Synechococcus are important primary producers in both types of ecosystems. We have found that the genome of a coastal cyanobacterium, Synechococcus sp. strain CC9311, has significant differences from an open ocean strain, Synechococcus sp. strain WH8102, and these are consistent with the differences between their respective environments. CC9311 has a greater capacity to sense and respond to changes in its (coastal) environment. It has a much larger capacity to transport, store, use, or export metals, especially iron and copper. In contrast, phosphate acquisition seems less important, consistent with the higher concentration of phosphate in coastal environments. CC9311 is predicted to have differences in its outer membrane lipopolysaccharide, and this may be characteristic of the speciation of some cyanobacterial groups. In addition, the types of potentially horizontally transferred genes are markedly different between the coastal and open ocean genomes and suggest a more prominent role for phages in horizontal gene transfer in oligotrophic environments. %B Proceedings of the National Academy of Sciences %V 103 %P 13555–13559 %G eng %U https://www.pnas.org/content/103/36/13555 %R 10.1073/pnas.0602963103 %0 Journal Article %J Molecular Biology and Evolution %D 2006 %T Global dispersal and ancient cryptic species in the smallest marine eukaryotes %A Slapeta, Jan %A López-García, P %A Moreira, David %K Micromonas %K rcc %X Small eukaryotic species (¡1 mm) are thought to behave as prokaryotes in that, lacking geographical barriers to their dispersal due to their tiny size, they are ubiquitous. Accordingly, the absence of geographical insulation would imply the existence of a relatively small number of microeukaryotic species. To test these ideas, we sequenced and compared several nuclear, mitochondrial, and chloroplast genes from the isolates of a marine picoeukaryotic alga ([\~]2 microm), Micromonas pusilla, collected worldwide. Independent and combined phylogenetic analyses demonstrate that this traditional single morphospecies actually comprises several independent lineages, some of which are shown to be ubiquitous in oceans. However, while some lineages group closely related strains, others form distant clusters, revealing the existence of cryptic species. Moreover, molecular dating using a relaxed clock suggests that their first diversification may have started as early as during the Late Cretaceous ([\~]65 MYA), implying that "M. pusilla" is the oldest group of cryptic species known to date. Our results illustrate that global dispersal of a picoeukaryote is possible in oceans, but this does not imply a reduced species number. On the contrary, we show that the morphospecies concept is untenable because it overlooks a large genetic and species diversity and may lead to incorrect biological assumptions. %B Molecular Biology and Evolution %V 23 %P 23–29 %G eng %U http://mbe.oxfordjournals.org/cgi/content/abstract/23/1/23 %R 10.1093/molbev/msj001 %0 Journal Article %J Applied and Environmental Microbiology %D 2006 %T Seasonal variations in virus-host populations in norwegian coastal waters: Focusing on the cyanophage community infecting marine synechococcus spp. %A Sandaa, R.-A. %A Larsen, Aud %K RCC2035 %X Viruses are ubiquitous components of the marine ecosystem. In the current study we investigated seasonal variations in the viral community in Norwegian coastal waters by pulsed-field gel electrophoresis (PFGE). The results demonstrated that the viral community was diverse, displaying dynamic seasonal variation, and that viral populations of 29 different sizes in the range from 26 to 500 kb were present. Virus populations from 260 to 500 kb and dominating autotrophic pico- and nanoeukaryotes showed similar dynamic variations. Using flow cytometry and real-time PCR, we focused in particular on one host-virus system: Synechococcus spp. and cyanophages. The two groups covaried throughout the year and were found in the highest amounts in fall with concentrations of 7.3 x 10(4) Synechococcus cells ml(-1) and 7.2 x 10(3) cyanophage ml(-1). By using primers targeting the g20 gene in PCRs on DNA extracted from PFGE bands, we demonstrated that cyanophages were found in a genomic size range of 26 to 380 kb. The genetic richness of the cyanophage community, determined by denaturing gradient gel electrophoresis (DGGE) of PCR-amplified g20 gene fragments, revealed seasonal shifts in the populations, with one community dominating in spring and summer and a different one dominating in fall. Phylogenetic analysis of the sequences originating from PFGE and DGGE bands grouped the sequences into three groups, all with homology to cyanomyoviruses present in cultures. Our results show that the cyanophage community in Norwegian coastal waters is dynamic and genetically diverse and has a surprisingly wide genomic size range. %B Applied and Environmental Microbiology %V 72 %P 4610–4618 %8 jul %G eng %U http://aem.asm.org/cgi/doi/10.1128/AEM.00168-06 %R 10.1128/AEM.00168-06 %0 Journal Article %J Molecular Biology and Evolution %D 2005 %T New insights into the nature and phylogeny of prasinophyte antenna proteins: Ostreococcus tauri, a case study %A Six, C %A Worden, A Z %A Rodriguez, F %A Moreau, H %A Partensky, F %K rcc %K RCC113 %K RCC114 %K RCC417 %K RCC745 %K SBR$_\textrmP$hyto$_\textrmD$PO %X The basal position of the Mamiellales (Prasinophyceae) within the green lineage makes these unicellular organisms key to elucidating early stages in the evolution of chlorophyll a/b–binding light-harvesting complexes (LHCs). Here, we unveil the complete and unexpected diversity of Lhc proteins in Ostreococcus tauri, a member of the Mamiellales order, based on results from complete genome sequencing. Like Mantoniella squamata, O. tauri possesses a number of genes encoding an unusual prasinophyte-specific Lhc protein type herein designated "Lhcp". Biochemical characterization of the complexes revealed that these polypeptides, which bind chlorophylls a, b, and a chlorophyll c–like pigment (Mg-2,4-divinyl-phaeoporphyrin a5 monomethyl ester) as well as a number of unusual carotenoids, are likely predominant. They are retrieved to some extent in both reaction center I (RCI)– and RCII-enriched fractions, suggesting a possible association to both photosystems. However, in sharp contrast to previous reports on LHCs of M. squamata, O. tauri also possesses other LHC subpopulations, including LHCI proteins (encoded by five distinct Lhca genes) and the minor LHCII polypeptides, CP26 and CP29. Using an antibody against plant Lhca2, we unambiguously show that LHCI proteins are present not only in O. tauri, in which they are likely associated to RCI, but also in other Mamiellales, including M. squamata. With the exception of Lhcp genes, all the identified Lhc genes are present in single copy only. Overall, the discovery of LHCI proteins in these prasinophytes, combined with the lack of the major LHCII polypeptides found in higher plants or other green algae, supports the hypothesis that the latter proteins appeared subsequent to LHCI proteins. The major LHC of prasinophytes might have arisen prior to the LHCII of other chlorophyll a/b–containing organisms, possibly by divergence of a LHCI gene precursor. However, the discovery in O. tauri of CP26-like proteins, phylogenetically placed at the base of the major LHCII protein clades, yields new insight to the origin of these antenna proteins, which have evolved separately in higher plants and green algae. Its diverse but numerically limited suite of Lhc genes renders O. tauri an exceptional model system for future research on the evolution and function of LHC components. %B Molecular Biology and Evolution %V 22 %P 2217–2230 %G eng %R 10.1093/molbev/msi220 %0 Book Section %B Algal culturing techniques %D 2005 %T Phytoplankton cell counting by flow cytometry %A Marie, D %A Simon, N %A Vaulot, D %E Andersen, R A %K 2005 %K PICODIV %K rcc %K SBR$_\textrmP$hyto$_\textrmD$PO %K sbr?hyto %B Algal culturing techniques %I Academic Press %P 253–267 %G eng %0 Journal Article %J Journal of Bacteriology %D 2005 %T Two novel phycoerythrin-associated linker proteins in the marine cyanobacterium synechococcus sp. Strain WH8102 %A Six, Christophe %A Thomas, Jean-Claude %A Thion, Laurent %A Lemoine, Yves %A Zal, Frank %A Partensky, Frédéric %K 2005 %K rcc %K SBR$_\textrmP$hyto %K sbr?hyto %X The recent availability of the whole genome of Synechococcus sp. strain WH8102 allows us to have a global view of the complex structure of the phycobilisomes of this marine picocyanobacterium. Genomic analyses revealed several new characteristics of these phycobilisomes, consisting of an allophycocyanin core and rods made of one type of phycocyanin and two types of phycoerythrins (I and II). Although the allophycocyanin appears to be similar to that found commonly in freshwater cyanobacteria, the phycocyanin is simpler since it possesses only one complete set of alpha and beta subunits and two rod-core linkers (CpcG1 and CpcG2). It is therefore probably made of a single hexameric disk per rod. In contrast, we have found two novel putative phycoerythrin-associated linker polypeptides that appear to be specific for marine Synechococcus spp. The first one (SYNW2000) is unusually long (548 residues) and apparently results from the fusion of a paralog of MpeC, a phycoerythrin II linker, and of CpeD, a phycoerythrin-I linker. The second one (SYNW1989) has a more classical size (300 residues) and is also an MpeC paralog. A biochemical analysis revealed that, like MpeC, these two novel linkers were both chromophorylated with phycourobilin. Our data suggest that they are both associated (partly or totally) with phycoerythrin II, and we propose to name SYNW2000 and SYNW1989 MpeD and MpeE, respectively. We further show that acclimation of phycobilisomes to high light leads to a dramatic reduction of MpeC, whereas the two novel linkers are not significantly affected. Models for the organization of the rods are proposed. %B Journal of Bacteriology %V 187 %P 1685–1694 %G eng %U http://jb.asm.org/cgi/content/abstract/187/5/1685 %R 10.1128/JB.187.5.1685-1694.2005 %0 Journal Article %J Journal of Phycology %D 2004 %T Pigment suites and taxonomic groups in Prasinophyceae %A Latasa, Mikel %A Scharek, Renate %A Gall, Florence Le %A Guillou, Laure %A Le Gall, F %K 2004 %K PICODIV %K rcc %K SBR$_\textrmP$hyto$_\textrmD$PO %K sbr?hyto %B Journal of Phycology %V 40 %P 1149–1155 %8 dec %G eng %U http://doi.wiley.com/10.1111/j.1529-8817.2004.03136.x %R 10.1111/j.1529-8817.2004.03136.x %0 Journal Article %J Plant Physiology %D 2004 %T Starch division and partitioning. A mechanism for granule propagation and maintenance in the picophytoplanktonic green alga Ostreococcus tauri %A Ral, J P %A Derelle, E %A Ferraz, C %A Wattebled, F %A Farinas, B %A Corellou, F %A Buleon, A %A Slomianny, M C %A Delvalle, D %A D, Hulst C %A Rombauts, S %A Moreau, H %A Ball, S %K Adp Glucose Pyrophosphorylase %K Amylopectin %K Arabidopsis %K Bacterial Glycogen %K Biogenesis %K Biosynthesis %K Chlamydomonas Reinhardtii %K Enzyme %K Prasinophyceae %K rcc %K RCC745 %K Synthase %X Whereas Glc is stored in small-sized hydrosoluble glycogen particles in archaea, eubacteria, fungi, and animal cells, photosynthetic eukaryotes have resorted to building starch, which is composed of several distinct polysaccharide fractions packed into a highly organized semicrystalline granule. In plants, both the initiation of polysaccharide synthesis and the nucleation mechanism leading to formation of new starch granules are currently not understood. Ostreococcus tauri, a unicellular green alga of the Prasinophyceae family, defines the tiniest eukaryote with one of the smallest genomes. We show that it accumulates a single starch granule at the chloroplast center by using the same pathway as higher plants. At the time of plastid division, we observe elongation of the starch and division into two daughter structures that are partitioned in each newly formed chloroplast. These observations suggest that in this system the information required to initiate crystalline polysaccharide growth of a new granule is contained within the preexisting polysaccharide structure and the design of the plastid division machinery. %B Plant Physiology %V 136 %P 3333–3340 %G eng %R 10.1104/pp.104.044131 %0 Journal Article %J Applied and Environmental Microbiology %D 2003 %T Clade-specific 16S ribosomal DNA oligonucleotides reveal the predominance of a single marine Synechococcus clade throughout a stratified water column in the Red Sea %A Fuller, Nicholas J %A Marie, Dominique %A Partensky, Frédéric %A Vaulot, Daniel %A Post, Anton F %A Scanlan, David J %K 2003 %K PICODIV %K rcc %K SBR$_\textrmP$hyto %K sbr?hyto %X Phylogenetic relationships among members of the marine Synechococcus genus were determined following sequencing of the 16S ribosomal DNA (rDNA) from 31 novel cultured isolates from the Red Sea and several other oceanic environments. This revealed a large genetic diversity within the marine Synechococcus cluster consistent with earlier work but also identified three novel clades not previously recognized. Phylogenetic analyses showed one clade, containing halotolerant isolates lacking phycoerythrin (PE) and including strains capable, or not, of utilizing nitrate as the sole N source, which clustered within the MC-A (Synechococcus subcluster 5.1) lineage. Two copies of the 16S rRNA gene are present in marine Synechococcus genomes, and cloning and sequencing of these copies from Synechococcus sp. strain WH 7803 and genomic information from Synechococcus sp. strain WH 8102 reveal these to be identical. Based on the 16S rDNA sequence information, clade-specific oligonucleotides for the marine Synechococcus genus were designed and their specificity was optimized. Using dot blot hybridization technology, these probes were used to determine the in situ community structure of marine Synechococcus populations in the Red Sea at the time of a Synechococcus maximum during April 1999. A predominance of genotypes representative of a single clade was found, and these genotypes were common among strains isolated into culture. Conversely, strains lacking PE, which were also relatively easily isolated into culture, represented only a minor component of the Synechococcus population. Genotypes corresponding to well-studied laboratory strains also appeared to be poorly represented in this stratified water column in the Red Sea. %B Applied and Environmental Microbiology %V 69 %P 2430–2443 %G eng %U http://aem.asm.org/cgi/content/abstract/69/5/2430 %R 10.1128/AEM.69.5.2430-2443.2003 %0 Journal Article %J Applied and Environmental Microbiology %D 2003 %T Quantitative assessment of picoeucaryotes in the natural environment using taxon specific oligonucleotide probes in association with TSA-FISH (Tyramide Signal Amplification - Fluorescent In Situ Hybridization) and flow cytometry %A Biegala, I C %A Not, F %A Vaulot, D %A Simon, N %K 2003 %K PICODIV %K rcc %K SBR$_\textrmP$hyto %K sbr?hyto %K SOMLIT %B Applied and Environmental Microbiology %V 69 %P 5519–5529 %G eng %R 10.1128/AEM.69.9.5519-5529.2003 %0 Journal Article %J Journal of Phycology %D 2003 %T A transient bloom of ¡i¿Ostreococcus¡/i¿ (chlorophyta, prasinophyceae) in west neck bay, long island, new york %A O'Kelly, C J %A Sieracki, M E %A Thier, E C %A Hobson, I C %K Aureococcus Anophagefferens Pelagophyceae %K bloom dynamics %K Gen %K Microalga %K Ostreococcus %K picoalgae %K picoplankton %K rcc %X The smallest known eukaryote, Ostreococcus tauri Courties et Chretiennot-Dinet, was first reported as the dominant picoplankter in a French lagoon known for its diverse phytoplankton community and high oyster productivity. Long-term seasonal blooms of this picoeukaryote were observed in association with stable plankton communities. On 5 June 2001, a distinctive monotypic picoplankton bloom was detected by flow cytometry as part of an ongoing study of "brown tide" (Aureococcus anophagefferens) bloom initiation in Long Island bays. The bloom reached a concentration of 5 x 10(5) cells.mL(-1) in West Neck Bay and lasted less than 2 weeks. Epifluorescence microscopy and TEM indicated that the bloom organism was an Ostreococcus-like picoalga, the first ever observed in a Long Island bay. Many cells of this alga contained numerous virus-like particles. The Ostreococcus-like picoalga, which resembles O. tauri, was rare in samples collected the following week. Instead, a substantial increase in the Synechococcus population was observed. Such rapid population changes have not previously been reported for Ostreococcus. Viral lysis and grazing by heterotrophic nanoflagellates may have contributed to the rapid decline of the Ostreococcus-like cells in West Neck Bay. %B Journal of Phycology %V 39 %P 850–854 %G eng %R 10.1046/j.1529-8817.2003.02201.x %0 Journal Article %D 2002 %T Application of fluorescent in situ hybridization coupled with tyramide signal amplification (FISH-TSA) to assess eukaryotic picoplankton composition %A Not, F %A Simon, N %A Biegala, IC %A Vaulot, D %K rcc %X Photosynthetic picoeukaryotes (phytoplankton cells with a diameter smaller than 2 to 3 ??m) contribute significantly to both biomass and primary production in the oligotrophic open ocean and coastal waters, at certain times of the year. The identification of these organisms is difficult because of their small size and simple morphology, therefore hindering detailed ecological studies of their distribution and role. In this paper, we demonstrate the use of oligonucleotide probes specific to algal classes or to lower order taxa in combination with fluorescent in situ hybridization and tyramide signal amplification (FISH-TSA) to determine eukaryotic picophytoplankton diversity. Target cells were detected and enumerated using epifluorescence microscopy. The sensitivity of the technique and the specificity of the probes were tested on pure and mixed picoplanktonic strains, as well as on natural samples from the English Channel. In these samples, the community was dominated by cells belonging to the division Chlorophyta. Haptophyta, Bolidophyceae and Pelagophyceae were also detected at low abundance. The FISH-TSA method is readily applicable to the study of picoplankton diversity in natural communities. %V 28 %P 157–166 %G eng %R 10.3354/ame028157 %0 Journal Article %J Journal of Phycology %D 2002 %T DNA libraries for sequencing the genome of Ostreococcus tauri (Chlorophyta, Prasinophyceae): The smallest free-living eukaryotic cell %A Derelle, E %A Ferraz, C %A Lagoda, P %A Eychenie, S %A Cooke, R %A Regad, F %A Sabau, X %A Courties, C %A Delseny, M %A Demaille, J %A Picard, A %A Moreau, H %K Pico$_\textrmR$eview %K rcc %K RCC745 %X Ostreococcus tauri is a marine photosynthetic picoeukaryote presenting a minimal cellular organization with one nucleus, one chloroplast, and one mitochondrion. It has the smallest genome described among free-living eukaryotic cells, and we showed by pulsed-field gel electrophoresis (PFGE) that it is divided between 15 bands ranging from 1.2 to 0.15 Mb, giving a total size of 9.7 Mb. A Bacterial Artificial Chromosome (BAC) library was prepared from genomic DNA extracted from a culture of O. tauri. A total of 2457 clones was obtained with an average insert size of around 70 kb, representing an 18-fold coverage of the genome. The library was spotted on high density filters, and several probes of coding sequences were hybridized to both the high density BAC library filters and directly to the dried PFGE gels of the O. tauri genomic DNA. These hybridizations allowed a preliminary organization of the library and the localization of several markers on the chromosomes. Randomly selected fragments were also sequenced, representing 12% of the O. tauri genome. Many sequences showed significant similarities in data banks, mainly with plant and algae sequences. About 1000 coding sequences could be identified. These data confirmed the position of O. tauri in the green lineage and the hypothesis of a very compact organization of its genome. %B Journal of Phycology %V 38 %P 1150–1156 %G eng %U c:%5CDV%5CPapers reprints%5CPhytoplankton Physiology%5CDerelle Ostreococcus DNA libraries JPhycol 02.pdf %R 10.1046/j.1529-8817.2002.02021.x %0 Journal Article %J Microbiology - UK %D 2001 %T Closely related Prochlorococcus genotypes show remarkably different depth distributions in two oceanic regions as revealed by in situ hybridization using 16S rRNA-targeted oligonucleotides %A West, N J %A Schonhuber, W A %A Fuller, N J %A Amann, R I %A Rippka, R %A Post, A F %A Scanlan, D J %K Escherichia Coli %K IDENTIFICATION %K Marine Cyanobacterium %K Nucleic Acid Probes %K Photosynthetic Prokaryote %K PICODIV %K Populations %K rcc %K Ribosomal Rna %K SEQUENCES %K Tyramide Signal Amplification %K Whole Cell Hybridization %X An in situ hybridization method was applied to the identification of marine cyanobacteria assignable to the genus Procholorococcus using harseradish-peroxidase-labelled 16S rRNA-targeted oligonucleotide probes in combination with tyramide signal amplification (TSA). With this method very bright signals were obtained, in contrast to hybridizations with oligonucleotides monolabelled with fluorochromes, which failed to give positive signals. Genotype-specific oligonucleotides for high light (HL)- and low light (LL)adapted members of this genus were identified by 16S rRNA sequence analyses and their specificities confirmed in whole-cell hybridizations with cultured strains of Prochlorococcus marinus Chisholm et al., 1992, Prochlorococcus sp. and Synechococcus sp. In situ hybridization of these genotype-specific probes to field samples from stratified water bodies collected in the North Atlantic Ocean and the Red Sea allowed a rapid assessment of the abundance and spatial distribution of HL- and LL-adapted Prochlorococcus. In both oceanic regions the LL-adapted Prochlorococcus populations were localized in deeper water whereas the HL-adapted Prochlorococcus populations were not only distinct in each region but also exhibited strikingly different depth distributions, HLI being confined to shallow wafer in the North Atlantic, in contrast to HLII, which was present throughout the water column in the Red Sea. %B Microbiology - UK %V 147 %P 1731–1744 %G eng %R 10.1099/00221287-147-7-1731 %0 Journal Article %J European Journal of Phycology %D 1996 %T High degree of genetic variation in Prochlorococcus (Prochlorophyta) revealed by RFLP analysis %A Scanlan, D J %A Hess, W R %A Partensky, F %A Newman, J %A Vaulot, D %K DIVINYL CHLOROPHYLL-A %K FAMILY %K Marine Synechococcus %K Mediterranean Sea %K Multiple Evolutionary Origins %K north-atlantic %K NUCLEOTIDE-SEQUENCE %K picoplankton %K Prokaryote %K rcc %K RCC SBR$_\textrmP$hyto %K UNICELLULAR CYANOBACTERIUM %B European Journal of Phycology %V 31 %P 1–9 %G eng %R 10.1080/09670269600651131 %0 Journal Article %J Marine Biology %D 1996 %T Vertical distributions and photosynthetic action spectra of two oceanic picophytoplankers, Prochlorococcus marinus and Synechococcus sp %A Shimada, A %A Maruyama, T %A Miyachi, S %K OPTICAL-PROPERTIES %K Photosynthesis %K rcc %K \#PROCHLOROCOCCUS %B Marine Biology %V 127 %P 15–23 %G eng %R 10.1007/BF00993639 %0 Journal Article %J Journal of Phycology %D 1994 %T Characterization of oceanic photosynthetic picoeukaryotes by flow cytometry analysis %A Simon, N %A Barlow, R G %A Marie, D %A Partensky, F %A Vaulot, D %K flow cytometry %K hplc %K pigments %K rcc %K RCC SBR$_\textrmP$hyto %K \#PICOPLANKTON %B Journal of Phycology %V 30 %P 922–935 %G eng %R 10.1111/j.0022-3646.1994.00922.x