%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 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 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 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 BMC Microbiology %D 2014 %T Diverse molecular signatures for ribosomally 'active' Perkinsea in marine sediments %A Chambouvet, Aurelie %A Berney, Cedric %A Romac, Sarah %A Audic, Stéphane %A Maguire, Finlay %A de Vargas, Colomban %A Richards, Thomas %K 2014 %K Biomarks %K rcc %K SBR$_\textrmP$hyto$_\textrmE$PPO %K sbr?hyto?ppo %X BACKGROUND:Perkinsea are a parasitic lineage within the eukaryotic superphylum Alveolata. Recent studies making use of environmental small sub-unit ribosomal RNA gene (SSU rDNA) sequencing methodologies have detected a significant diversity and abundance of Perkinsea-like phylotypes in freshwater environments. In contrast only a few Perkinsea environmental sequences have been retrieved from marine samples. Only two groups of Perkinsea have been cultured and morphologically described and these are parasites of marine molluscs or marine protists. These two marine groups form separate and distantly related phylogenetic clusters, composed of closely related lineages on SSU rDNA trees. Here, we test the hypothesis that Perkinsea are a hitherto under-sampled group in marine environments. Using 454 diversity 'tag' sequencing we investigate the diversity and distribution of these protists in marine sediments and water column samples taken from the Deep Chlorophyll Maximum (DCM) and sub-surface using both DNA and RNA as the source template and sampling four European offshore locations.RESULTS:We detected the presence of 265 sequences branching with known Perkinsea, the majority of them recovered from marine sediments. Moreover, 27% of these sequences were sampled from RNA derived cDNA libraries. Phylogenetic analyses classify a large proportion of these sequences into 38 cluster groups (including 30 novel marine cluster groups), which share less than 97% sequence similarity as to suggest this diversity encompasses a range of biologically and ecologically distinct organisms.CONCLUSIONS:These results demonstrate that the Perkinsea lineage is considerably more diverse than previously detected in marine environments. This wide diversity of Perkinsea-like protists is largely retrieved in marine sediment with a significant proportion detected in RNA derived libraries suggesting this diversity represents ribosomally 'active' and intact cells. Given the phylogenetic range of hosts infected by known Perkinsea parasites, these data suggest that Perkinsea either play a significant but hitherto unrecognized role as parasites in marine sediments and/or members of this group are present in the marine sediment possibly as part of the 'seed bank' microbial community. %B BMC Microbiology %V 14 %P 110 %G eng %U http://www.biomedcentral.com/1471-2180/14/110 %R 10.1186/1471-2180-14-110 %0 Journal Article %J Journal of Phycology %D 2014 %T Genetic delineation between and within the widespread coccolithophore morpho-species Emiliania huxleyi and Gephyrocapsa oceanica (Haptophyta) %A Bendif, El Mahdi %A Probert, Ian %A Carmichael, Margaux %A Romac, Sarah %A Hagino, Kyoko %A de Vargas, Colomban %K 2014 %K cc3549 %K rcc %K rcc1210 %K RCC1213 %K rcc1220 %K rcc1227 %K rcc1229 %K RCC1242 %K rcc1252 %K RCC1253 %K rcc1258 %K RCC1259 %K rcc1260 %K rcc1271 %K RCC1281 %K rcc1288 %K RCC1292 %K rcc1297 %K RCC1300 %K RCC1303 %K RCC1305 %K RCC1316 %K RCC1562 %K rcc174 %K RCC1839 %K rcc3545 %K rrcc1247 %K SBR$_\textrmP$hyto$_\textrmE$PPO %K sbr?hyto?ppo %B Journal of Phycology %V 50 %P 140–148 %G eng %R 10.1111/jpy.12147 %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 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 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 Environmental Microbiology %D 2012 %T In situ survey of life cycle phases of the coccolithophore Emiliania huxleyi (Haptophyta) %A Frada, Miguel J %A Bidle, Kay D %A Probert, Ian %A de Vargas, Colomban %K 2012 %K rcc %K SBR$_\textrmP$hyto$_\textrmE$PPO %K sbr?hyto?ppo %X The cosmopolitan coccolithophore Emiliania huxleyi is characterized by a strongly differentiated haplodiplontic life cycle consisting of a diploid phase, generally bearing coccoliths (calcified) but that can be also non-calcified, and a non-calcified biflagellated haploid phase. Given most studies have focused on the bloom-producing calcified phase, there is little-to-no information about non-calcified cells in nature. Using field mesocoms as experimental platforms, we quantitatively surveyed calcified and non-calcified cells using the combined calcareous detection fluorescent in situ hybridization (COD-FISH) method and qualitatively screened for haploid specific transcripts using reverse transcription-PCR during E. huxleyi bloom successions. Diploid, calcified cells formed dense blooms that were followed by the massive proliferation of E. huxleyi viruses (EhVs), which caused bloom demise. Non-calcified cells were also detected throughout the experiment, accounting for a minor fraction of the population but becoming progressively more abundant during mid-late bloom periods concomitant with EhV burst. Non-calcified cell growth also paralleled a distinct window of haploid-specific transcripts and the appearance of autotrophic flagellates morphologically similar to haploid cells, both of which are suggestive of meiosis and sexual life cycling during natural blooms of this prominent marine phytoplankton species. %B Environmental Microbiology %V 14 %P 1558–1569 %G eng %U http://dx.doi.org/10.1111/j.1462-2920.2012.02745.x %R 10.1111/j.1462-2920.2012.02745.x %0 Journal Article %J Journal of Phycology %D 2011 %T Transcriptome analyses reveal differential gene expression patterns between the life-cycle stages of Emiliania huxleyi (Haptophyta) and reflect specialization to different ecological niches %A Rokitta, Sebastian D %A de Nooijer, Lennart J %A Trimborn, Scarlett %A de Vargas, Colomban %A Rost, Björn %A John, Uwe %K 2011 %K endocytosis %K Life-cycle stages %K microarray %K quantitative RT-PCR %K rcc %K SBR$_\textrmP$hyto$_\textrmE$PPO %K sbr?hyto?ppo %K transcriptome profiling %X Coccolithophores, especially the abundant, cosmopolitan species Emiliania huxleyi (Lohmann) W. W. Hay et H. P. Mohler, are one of the main driving forces of the oceanic carbonate pump and contribute significantly to global carbon cycling, due to their ability to calcify. A recent study indicates that termination of diploid blooms by viral infection induces life-cycle transition, and speculation has arisen about the role of the haploid, noncalcifying stage in coccolithophore ecology. To explore gene expression patterns in both life-cycle stages, haploid and diploid cells of E. huxleyi (RCC 1217 and RCC 1216) were acclimated to limiting and saturating photon flux densities. Transcriptome analyses were performed to assess differential genomic expression related to different ploidy levels and acclimation light intensities. Analyses indicated that life-cycle stages exhibit different properties of regulating genome expression (e.g., pronounced gene activation and gene silencing in the diploid stage), proteome maintenance (e.g., increased turnover of proteins in the haploid stage), as well as metabolic processing (e.g., pronounced primary metabolism and motility in the haploid stage and calcification in the diploid stage). Furthermore, higher abundances of transcripts related to endocytotic and digestive machinery were observed in the diploid stage. A qualitative feeding experiment indicated that both life-cycle stages are capable of particle uptake (0.5 ??m diameter) in late-stationary growth phase. Results showed that the two life-cycle stages represent functionally distinct entities that are evolutionarily shaped to thrive in the environment they typically inhabit. %B Journal of Phycology %V 47 %P 829–838 %G eng %U http://dx.doi.org/10.1111/j.1529-8817.2011.01014.x %R 10.1111/j.1529-8817.2011.01014.x %0 Journal Article %J Journal of Nannoplankton Research %D 2010 %T A guide to extant coccolithophores (Calcihaptophycidae, Haptophyta) using light microscopy. %A Frada, Miguel %A Young, Jeremy %A Cachão, Mário %A Lino, Sílvia %A Martins, Ana %A Narciso, Áurea %A Probert, Ian %A de Vargas, Colomban %K 2010 %K ? No DOI found %K rcc %K SBR$_\textrmP$hyto$_\textrmE$PPO %K sbr?hyto?ppo %B Journal of Nannoplankton Research %V 31 %P 58–112 %G eng %0 Journal Article %J Molecular Biology and Evolution %D 2010 %T A timeline of the environmental genetics of the haptophytes %A Liu, Hui %A Aris-Brosou, Stephane %A Probert, Ian %A de Vargas, Colomban %K 2010 %K rcc %K SBR$_\textrmP$hyto$_\textrmE$PPO %K sbr?hyto?ppo %X The use of genomic data and the rise of phylogenomics have radically changed our view of the eukaryotic tree of life at a high taxonomic level by identifying four to six "supergroups". Yet our understanding of the evolution of key innovations within each of these supergroups is limited because of poor species sampling relative to the massive diversity encompassed by each supergroup. Here we apply a multigene approach that incorporates a wide taxonomic diversity to infer the timeline of the emergence of strategic evolutionary transitions in the haptophytes, a group of ecologically and biogeochemically significant marine protists that belong to the Chromalveolata supergroup. Four genes (SSU, LSU, tufA and rbcL) were extensively analyzed under several Bayesian models to assess the robustness of the phylogeny, particularly with respect to (i) data partitioning, (ii) the origin of the genes (host vs. endosymbiont), (iii) across-site rate variation and (iv) across-lineage rate variation. We show with a relaxed clock analysis that the origin of haptophytes dates back to 824 MYA (95% highest probability density 1031-637 MYA). Our dating results show that the ability to calcify evolved earlier than previously thought, between 329-291 MYA, in the Carboniferous period, and that the transition from mixotrophy to autotrophy occurred during the same time period. Although these two transitions precede a habitat change of major diversities from coastal / neritic waters to the pelagic realm (291-243 MYA, around the P/Tr boundary event), the emergence of calcification, full autotrophy and oceanic lifestyle seem mutually independent. %B Molecular Biology and Evolution %V 27 %P 171–176 %G eng %U http://mbe.oxfordjournals.org/cgi/content/abstract/msp222v1 %R 10.1093/molbev/msp222 %0 Journal Article %J Genome Biology %D 2009 %T Transcriptome analysis of functional differentiation between haploid and diploid cells of Emiliania huxleyi, a globally significant photosynthetic calcifying cell %A von Dassow, Peter %A Ogata, Hiroyuki %A Probert, Ian %A Wincker, Patrick %A Da Silva, Corinne %A Audic, Stéphane %A Claverie, Jean-Michel %A de Vargas, Colomban %K 2009 %K rcc %K RCC1216 %K rcc1217 %K SBR$_\textrmP$hyto$_\textrmE$PPO %K sbr?hyto?ppo %X BACKGROUND:Eukaryotes are classified as either haplontic, diplontic, or haplo-diplontic, depending on which ploidy levels undergo mitotic cell division in the life cycle. Emiliania huxleyi is one of the most abundant phytoplankton species in the ocean, playing an important role in global carbon fluxes, and represents haptophytes, an enigmatic group of unicellular organisms that diverged early in eukaryotic evolution. This species is haplo-diplontic. Little is known about the haploid cells, but they have been hypothesized to allow persistence of the species between the yearly blooms of diploid cells. We sequenced over 38000 Expressed Sequence Tags (ESTs) from haploid and diploid E. huxleyi normalized cDNA libraries to identify genes involved in important processes specific to each life phase (2N calcification or 1N motility), and to better understand the haploid phase of this prominent haplo-diplontic organism.RESULTS:The haploid and diploid transcriptomes showed a dramatic differentiation, with [almost equal to]20% greater transcriptome richness in diploid cells than in haploid cells and only [less than or equal to]50% of transcripts estimated to be common between the two phases. The major functional category of transcripts differentiating haploids included signal transduction and motility genes. Diploid-specific transcripts included Ca2+, H+, and HCO3- pumps. Potential factors differentiating the transcriptomes included haploid-specific Myb transcription factor homologs and an unusual diploid-specific histone H4 homolog.CONCLUSIONS:This study permitted the identification of genes likely involved in diploid-specific biomineralization, haploid-specific motility, and transcriptional control. Greater transcriptome richness in diploid cells suggests they may be more versatile for exploiting a diversity of rich environments whereas haploid cells are intrinsically more streamlined. %B Genome Biology %V 10 %P R114 %G eng %U http://genomebiology.com/2009/10/10/R114 %R 10.1186/gb-2009-10-10-r114 %0 Journal Article %J Proceedings of the National Academy of Sciences of the United States of America %D 2008 %T The “Cheshire Cat” escape strategy of the coccolithophore Emiliania huxleyi in response to viral infection %A Frada, Miguel %A Probert, Ian %A Allen, Michael J %A Wilson, William H %A de Vargas, Colomban %K 2008 %K rcc %K SBR$_\textrmP$hyto$_\textrmE$PPO %K sbr?hyto?ppo %X The coccolithophore is one of the most successful eukaryotes in modern oceans. The two phases in its haplodiploid life cycle exhibit radically different phenotypes. The diploid calcified phase forms extensive blooms, which profoundly impact global biogeochemical equilibria. By contrast, the ecological role of the noncalcified haploid phase has been completely overlooked. Giant phycodnaviruses ( viruses, EhVs) have been shown to infect and lyse diploid-phase cells and to be heavily implicated in the regulation of populations and the termination of blooms. Here, we demonstrate that the haploid phase of is unrecognizable and therefore resistant to EhVs that kill the diploid phase. We further show that exposure of diploid to EhVs induces transition to the haploid phase. Thus we have clearly demonstrated a drastic difference in viral susceptibility between life cycle stages with different ploidy levels in a unicellular eukaryote. Resistance of the haploid phase of provides an escape mechanism that involves separation of meiosis from sexual fusion in time, thus ensuring that genes of dominant diploid clones are passed on to the next generation in a virus-free environment. These “Cheshire Cat†ecological dynamics release host evolution from pathogen pressure and thus can be seen as an opposite force to a classic “Red Queen†coevolutionary arms race. In , this phenomenon can account for the fact that the selective balance is tilted toward the boom-and-bust scenario of optimization of both growth rates of calcifying cells and infectivity of EhVs. %B Proceedings of the National Academy of Sciences of the United States of America %V 105 %P 15944–15949 %G eng %R 10.1073/pnas.0807707105