%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 Journal Article %J Global Biogeochemical Cycles %D 2023 %T Biodiversity and stoichiometric plasticity increase pico-phytoplankton contributions to marine net primary productivity and the biological pump %A Letscher, Robert T. %A Moore, J. Keith %A Martiny, Adam C. %A Lomas, Michael W. %K carbon export %K net primary productivity %K pico-phytoplankton %K rcc162 %K rcc1677 %K rcc212 %K rcc289 %K rcc296 %K rcc30 %K rcc438 %K variable C:P %X Earth System Models generally predict increasing upper ocean stratification from 21st century warming, which will cause a decrease in the vertical nutrient flux forcing declines in marine net primary productivity (NPP) and carbon export. Recent advances in quantifying marine ecosystem carbon to nutrient stoichiometry have identified large latitudinal and biome variability, with low-latitude oligotrophic systems harboring pico-sized phytoplankton exhibiting large phosphorus to carbon cellular plasticity. Climate forced changes in nutrient flux stoichiometry and phytoplankton community composition is thus likely to alter the ocean’s biogeochemical response and feedback with the carbon-climate system. We have added three pico-phytoplankton functional types within the Biogeochemical Elemental Cycling component of the Community Earth System Model while incorporating variable cellular phosphorus to carbon stoichiometry for all represented phytoplankton types. The model simulates Prochlorococcus and Synechococcus populations that dominate the productivity and sinking carbon export of the tropical and subtropical ocean, and pico-eukaryote populations that contribute significantly to productivity and export within the subtropical to mid-latitude transition zone, with the western subtropical regions of each basin supporting the most P-poor stoichiometries. Subtropical gyre recirculation regions along the poleward flanks of surface western boundary currents are identified as regional hotspots of enhanced carbon export exhibiting C-rich/P-poor stoichiometry, preferentially inhabited by pico-eukaryotes and diatoms. Collectively, pico-phytoplankton contribute ∼58% of global NPP and ∼46% of global particulate organic carbon export below 100 meters through direct and ecosystem processing pathways. Biodiversity and cellular nutrient plasticity in marine pico-phytoplankton combine to increase their contributions to ocean productivity and the biological carbon pump. This article is protected by copyright. All rights reserved. %B Global Biogeochemical Cycles %V n/a %P e2023GB007756 %G eng %U https://onlinelibrary.wiley.com/doi/abs/10.1029/2023GB007756 %R 10.1029/2023GB007756 %0 Journal Article %J Environmental Microbiology Reports %D 2023 %T Biogenic silica accumulation in picoeukaryotes: Novel players in the marine silica cycle %A Churakova, Yelena %A Aguilera, Anabella %A Charalampous, Evangelia %A Conley, Daniel J. %A Lundin, Daniel %A Pinhassi, Jarone %A Farnelid, Hanna %K RCC4221 %K RCC827 %X It is well known that the biological control of oceanic silica cycling is dominated by diatoms, with sponges and radiolarians playing additional roles. Recent studies have revealed that some smaller marine organisms (e.g. the picocyanobacterium Synechococcus) also take up silicic acid (dissolved silica, dSi) and accumulate silica, despite not exhibiting silicon dependent cellular structures. Here, we show biogenic silica (bSi) accumulation in five strains of picoeukaryotes (<2–3 μm), including three novel isolates from the Baltic Sea, and two marine species (Ostreococcus tauri and Micromonas commoda), in cultures grown with added dSi (100 μM). Average bSi accumulation in these novel biosilicifiers was between 30 and 92 amol Si cell−1. Growth rate and cell size of the picoeukaryotes were not affected by dSi addition. Still, the purpose of bSi accumulation in these smaller eukaryotic organisms lacking silicon dependent structures remains unclear. In line with the increasing recognition of picoeukaryotes in biogeochemical cycling, our findings suggest that they can also play a significant role in silica cycling. %B Environmental Microbiology Reports %V n/a %G eng %U https://onlinelibrary.wiley.com/doi/abs/10.1111/1758-2229.13144 %R 10.1111/1758-2229.13144 %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 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 Journal Article %J mSphere %D 2021 %T Bacterial Quorum-Sensing Signal Arrests Phytoplankton Cell Division and Impacts Virus-Induced Mortality %A Pollara, Scott B. %A Becker, Jamie W. %A Nunn, Brook L. %A Boiteau, Rene %A Repeta, Daniel %A Mudge, Miranda C. %A Downing, Grayton %A Chase, Davis %A Harvey, Elizabeth L. %A Whalen, Kristen E. %E McMahon, Katherine %K rcc1731 %X Interactions between phytoplankton and heterotrophic bacteria fundamentally shape marine ecosystems by controlling primary production, structuring marine food webs, mediating carbon export, and influencing global climate. Phytoplankton-bacterium interactions are facilitated by secreted compounds; however, linking these chemical signals, their mechanisms of action, and their resultant ecological consequences remains a fundamental challenge. The bacterial quorumsensing signal 2-heptyl-4-quinolone (HHQ) induces immediate, yet reversible, cellular stasis (no cell division or mortality) in the coccolithophore Emiliania huxleyi; however, the mechanism responsible remains unknown. Using transcriptomic and proteomic approaches in combination with diagnostic biochemical and fluorescent cell-based assays, we show that HHQ exposure leads to prolonged S-phase arrest in phytoplankton coincident with the accumulation of DNA damage and a lack of repair despite the induction of the DNA damage response (DDR). While this effect is reversible, HHQ-exposed phytoplankton were also protected from viral mortality, ascribing a new role of quorum-sensing signals in regulating multitrophic interactions. Furthermore, our data demonstrate that in situ measurements of HHQ coincide with areas of enhanced micro- and nanoplankton biomass. Our results suggest bacterial communication signals as emerging players that may be one of the contributing factors that help structure complex microbial communities throughout the ocean. %B mSphere %V 6 %P e00009–21, /msphere/6/3/mSph.00009–21.atom %G eng %U https://msphere.asm.org/content/6/3/e00009-21 %R 10.1128/mSphere.00009-21 %0 Journal Article %J ALGAE %D 2021 %T Bioluminescence capability and intensity in the dinoflagellate Alexandrium species %A Park, Sang Ah %A Jeong, Hae Jin %A Ok, Jin %A Kang, Heechang %A You, Jihyun %A Eom, Se %A Yoo, Yeong %A Lee, Moo Joon %K RCC4104 %X Some species in the dinoflagellate genus Alexandrium are bioluminescent. Of the 33 formally described Alexandrium species, the bioluminescence capability of only nine species have been tested, and eight have been reported to be bioluminescent. The present study investigated the bioluminescence capability of seven Alexandrium species that had not been tested. Alexandrium mediterraneum, A. pohangense, and A. tamutum were bioluminescent, but A. andersonii, A. hiranoi, A. insuetum, and A. pseudogonyaulax were not. We also measured the bioluminescent intensity of A. affine, A. fraterculus, A. mediterraneum, A. ostenfeldii, A. pacificum, A. pohangense, A. tamarense, and A. tamutum. The mean 200-second-integrated bioluminescence intensity per cell ranged from 0.02 to 32.2 × 104 relative luminescence unit per cell (RLU cell-1), and the mean maximum bioluminescence intensity per cell per second (BLMax) ranged from 0.01 to 10.3 × 104 RLU cell-1 s-1. BLMax was significantly correlated with the maximum growth rates of Alexandrium species, except for A. tamarense. A phylogenetic tree based on large subunit ribosomal DNA (LSU rDNA), showed that the bioluminescent species A. affine, A. catenella, A. fraterculus, A. mediterraneum, A. pacificum, and A. tamarense formed a large clade. However, the toxicity or mixotrophic capability of these species was split. Thus, their bioluminescence capability in this clade was more consistent than their toxicity or mixotrophic capability. Phylogenetic trees based on LSU rDNA and the luciferase gene of Alexandrium were consistent except for A. pohangense. The results of the present study can provide a basis for understanding the interspecific diversity in bioluminescence of Alexandrium. %B ALGAE %V 36 %G eng %R 10.4490/algae.2021.36.12.6 %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 Frontiers in Microbiology %D 2018 %T Bacterial epibiotic communities of ubiquitous and abundant marine diatoms are distinct in short- and long-term associations %A Crenn, Klervi %A Duffieux, Delphine %A Jeanthon, Christian %K 2018 %K Chaetoceros %K diatoms %K diversity %K heterotrophic bacteria %K interactions %K microbiome %K rcc %K RCC2560 %K RCC2565 %K Thalassiosira %K Western English Channel %X Interactions between phytoplankton and bacteria play a central role in mediatingbiogeochemical cycling and food web structure in the ocean. The cosmopolitan diatomsThalassiosiraandChaetocerosoften dominate phytoplankton communities in marinesystems. Past studies of diatom-bacterial associations have employed community-level methods and culture-based or natural diatom populations. Although bacterialassemblages attached to individual diatoms represents tight associations little is knownon their makeup or interactions. Here, we examined the epibiotic bacteria of 436Thalassiosiraand 329Chaetocerossingle cells isolated from natural samples andcollection cultures, regarded here as short- and long-term associations, respectively.Epibiotic microbiota of single diatom hosts was analyzed by cultivation and by cloning-sequencing of 16S rRNA genes obtained from whole-genome amplification products.The prevalence of epibiotic bacteria was higher in cultures and dependent of the hostspecies. Culture approaches demonstrated that both diatoms carry distinct bacterialcommunities in short- and long-term associations. Bacterial epibonts, commonlyassociated with phytoplankton, were repeatedly isolated from cells of diatom collectioncultures but were not recovered from environmental cells. Our results suggest thatin controlled laboratory culture conditions bacterial–diatom and bacterial–bacterialinteractions select for a simplified, but specific, epibiotic microbiota shaped and adaptedfor long-term associations. %B Frontiers in Microbiology %V 9 %P 1–12 %G eng %U https://www.frontiersin.org/article/10.3389/fmicb.2018.02879/full %R 10.3389/fmicb.2018.02879 %0 Journal Article %J bioRxiv %D 2018 %T A bHLH-PAS protein regulates light-dependent rhythmic processes in the marine diatom Phaeodactylum tricornutum %A Annunziata, Rossella %A Ritter, Andrés %A Fortunato, Antonio Emidio %A Cheminant-Navarro, Soizic %A Agier, Nicolas %A Huysman, Marie J. J. %A Winge, Per %A Bones, Atle %A Bouget, François-Yves %A Lagomarsino, Marco Cosentino %A Bouly, Jean Pierre %A Falciatore, Angela %K RCC2967 %X Periodic light dark cycles govern the timing of basic biological processes in organisms inhabiting land as well as the sea, where life evolved. Although prominent marine phytoplanktonic organisms such as diatoms show robust diurnal rhythms in growth, cell cycle and gene expression, the molecular bases controlling these processes are still obscure. By exploring the regulatory landscape of diatom diurnal rhythms, we here unveil the key function of a Phaeodactylum tricornutum bHLH-PAS protein, named Pt bHLH1a, in the regulation of light-dependent rhythms. Peak expression of Pt bHLH1a mRNA occurs at the end of the light period and it is adjusted to photoperiod changes. Ectopic over-expression of Pt bHLH1a results in lines with altered cell division and gene expression and showing a phase shift in diurnal responses, compared to the wild-type cells. Reduced oscillations in gene expression are also observed in continuous darkness, showing that the regulation of rhythmicity by Pt bHLH1a is not directly dependent on light inputs and cell division. Pt bHLH1a orthologs are widespread in both pennate and centric diatom genomes, hinting at a common function in many species. This study adds new elements to understand diatom biology and ecology and offers new perspectives to elucidate timekeeping mechanisms in marine organisms belonging to a major, but still underinvestigated branch of the tree of life. %B bioRxiv %P 271445 %G eng %U https://www.biorxiv.org/content/early/2018/02/25/271445 %R 10.1101/271445 %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 Frontiers in microbiology %D 2014 %T Bacteria in Ostreococcus tauri cultures - friends, foes or hitchhikers? %A Abby, Sophie S %A Touchon, Marie %A De Jode, Aurelien %A Grimsley, Nigel %A Piganeau, Gwenael %K bacterial diversity %K Bacterial symbiosis %K Illumina sequencing %K microbiome %K Ostreococcus %K phycosphere %K phytoplankton %K picoeukaryote %K rcc %K RCC?o?dd %K secretion system %X Marine phytoplankton produce half of the oxygen we breathe and their astounding diversity is just starting to be unraveled. Many microbial phytoplankton are thought to be phototrophic, depending solely on inorganic sources of carbon and minerals for growth rather than preying on other planktonic cells. However, there is increasing evidence that symbiotic associations, to a large extent with bacteria, are required for vitamin or nutrient uptake for many eukaryotic microalgae. Here, we use in silico approaches to look for putative symbiotic interactions by analysing the gene content of microbial communities associated with 13 different Ostreococcus tauri (Chlorophyta, Mamilleophyceae) cultures sampled from the Mediterranean Sea. While we find evidence for bacteria in all cultures, there is no ubiquitous bacterial group, and the most prevalent group, Flavobacteria, is present in 10 out of 13 cultures. Among seven of the microbiomes, we detected genes predicted to encode type 3 secretion systems (T3SS, in 6/7 microbiomes) and/or putative type 6 secretion systems (T6SS, in 4/7 microbiomes). Phylogenetic analyses show that the corresponding genes are closely related to genes of systems identified in bacterial-plant interactions, suggesting that these T3SS might be involved in cell-to-cell interactions with O. tauri. %B Frontiers in microbiology %V 5 %P 505 %8 jan %G eng %U http://journal.frontiersin.org/Journal/10.3389/fmicb.2014.00505/abstract %R 10.3389/fmicb.2014.00505 %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 Marine Drugs %D 2013 %T Bioprospecting marine plankton %A Abida, Heni %A Ruchaud, Sandrine %A Rios, Laurent %A Humeau, Anne %A Probert, Ian %A de Vargas, Colomban %A Bach, Stéphane %A Bowler, Chris %K 2013 %K MicroB3 %K rcc %K SBR$_\textrmP$hyto$_\textrmD$PO %K sbr?hyto$_\textrmd$ipo %K sbr?hyto?ppo %B Marine Drugs %V 11 %P 4594–4611 %G eng %U http://www.mdpi.com/1660-3397/11/11/4594 %R 10.3390/md11114594 %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 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 Journal of Phycology %D 1999 %T Bolidomonas: a new genus with two species belonging to a new algal class, the Bolidophyceae (Heterokonta) %A Guillou, L %A Chrétiennot-Dinet, M.-J. %A Medlin, L K %A Claustre, H %A Loiseaux-de Goër, S %A Vaulot, D %K 10$_\textrmb$est %K 1999 %K Bolidophyceae %K CELL-CYCLE %K CHRYSOPHYCEAE %K diatoms %K DIVINYL-CHLOROPHYLL %K FINE-STRUCTURE %K FLAGELLAR APPARATUS %K Heterokonta %K Marine %K marine picoeukaryotes %K oligotrophic ocean %K rcc %K RNA %K SBR$_\textrmP$hyto %K sbr?hyto %K SEQUENCE %K sp-nov %K stramenopiles %K ultrastructure %X A new algal class, the Bolidophyceae (Heterokonta), is described from one genus, Bolidomonas, gen, nov., and two species, Bolidomonas pacifica, sp, nov and Bolidomonas mediterranea, sp, nov., isolated from the equatorial Pacific Ocean and the Mediterranean Sea, respectively. Both species are approximately 1.2 mu m in diameter and have two unequal flagella; the longer flagellum bears tubular hairs, whereas the shorter is smooth. The flagellar basal apparatus is restricted to two basal bodies, and there is no transitional helix. Cells are naked, devoid of walls or siliceous structures. The internal cellular organization is simple with a single plastid containing a ring genophore and a girdle lamella, one mitochondrion with tubular cristae, and one Golgi apparatus close to the basal bodies. The Mediterranean and the Pacific species differ in the insertion angle between their flagella and their pattern of swimming, these differences possibly being linked to each other. Analyses of the SSU rDNA gene place the two strains as a sister group to the diatoms, Moreover, pigment analyses confirm this position, as fucoxanthin is found as the major carotenoid in both lineages. These data strongly suggest that the ancestral heterokont that gave rise to the diatom lineage was probably a biflagellated unicell. %B Journal of Phycology %V 35 %P 368–381 %G eng %R 10.1046/j.1529-8817.1999.3520368.x %0 Book Section %B Photosynthetic picoplankton %D 1986 %T Biological and ecological characterization of the marine unicellular cyanobacterium Synechococcus %A Waterbury, J B %A Watson, S W %A Valois, F W %A Franks, D G %E Platt, T %E Li, W K W %K Canad. Bull. Fish. Aquatic Sci. %K phytoplankton %K rcc %K Synechococcus %B Photosynthetic picoplankton %V 214 %P 71–120 %G eng