Diversity of Eukaryotic Marine Photosynthetic Picoplankton 43ème Réunion du Groupement des Protistologues de Langue Française 16-18 Mai 2005— Dourdan Diversity of Eukaryotic Marine Photosynthetic Picoplankton La présentation est restreinte aux picoplancton photosynthétique car la partie hétérotrophe sera couverte par la présentation suivante de R. Massana Daniel Vaulot Station Biologique de Roscoff CNRS and Université Paris 6, France
Outline Introduction Described species Environmental analysis : 18S and 16S rDNA An important group the Prasinophyceae Perspectives To say - Restrict to euphotic zone mostly
Photosynthetic picoplankton Prochlorococcus Synechococcus Picoeucaryotes Chlorophyll Side scatter © D. Marie
Key questions What are they ? How abundant is each group ? Where and when specific groups occur ? What is their role ?
Outline Introduction Described species To say - Restrict to euphotic zone mostly
Described species About 40 species Chorophyta Chlorophyceae Prasinophyceae Trebouxiophyceae Heterokontophyta (Stramenopiles) Bacillariophyceae Bolidophyceae Chrysophyceae (?) Dictyochophyceae Eustigmatophyceae Pelagophyceae Pinguiophyceae Haptophyta Prymnesiophyceae
Eukaryotic lineages Baldauf 2003, Science
Prasinophyceae Guillou et al. 2004
Mamiellales Ostreococcus Bathycoccus Micromonas Guillou et al.2004 Protist
Pseudoscourfeldiales Prasinococcales Prasinococcus Bathycoccus Pycnococcus / Pseudoscourfeldia Clade VII RCC 287
Trebouxiophyceae Picochlorum (5 species, 4 of which basionym = Nannochloris) Henley et al.2004 Phycologia
Heterokontophyta
Pelagophyceae Aureococcus anophagefferens Aureoumbra lagunensis Pelagomonas calceolata Pelagococcus subviridis
Bolidophyceae Bolidomonas mediterranea Bolidomonas pacifica
Eustigmatophyceae Dictyochophyceae Chrysophyceae ? Pinguiophyceae Florenciella parvula Nannochloropsis (6 species) Chrysophyceae ? Pinguiophyceae Parmales Pinguiochrysis pyriformis
Haptophyta Trigonapsis minutissima Imantonia rotunda Chrysochromulina leadbeateri (+ several species)
Outline Introduction Described species Environmental analysis : 18S and 16S rDNA To say - Restrict to euphotic zone mostly
Sequencing 18 S rDNA Equatorial Pacific Group II Group I Moon et al. 2001, Nature
Photosynthetic groups Dictyochophyceae Equatorial Pacific
Clone libraries Autotrophs: 23% Dinophyceae 50% of sequences correspond to unknown alveolates Autotrophs: 23% Moon et al 2001
Prymnesiophyceae
18S clone libraries
Autotrophs: 48 % Channel : April 2000 Prasinophytes Cryptophytes Romari and Vaulot 2004
Eukaryotic lineages ? Baldauf 2003, Science
Outline Introduction Described species Environmental analysis : 18S and 16S rDNA An important group, the Prasinophyceae To say - Restrict to euphotic zone mostly
Prasinophyceae Prasinococcus Guillou et al. Protist 2004
Prasinophyceae English Channel seasonnal cycle FISH Not et al. 2004 AEM Ajouter données arctique et océan indien
Prasinophyceae Arctic Ocean FISH Not et al. in press Coast Ocean Atlantic Arctic Micromonas Bathycoccus
Mediterranean Sea Q PCR Marie et al. submitted
(cf. H. Moreau presentation) Sporadic, open ocean and lagoons Coastal, open ocean Very abundant in coastal temperate waters Ecotypic variability ! (cf. H. Moreau presentation)
Ecotypic diversity Ostreococcus spp. 4 clades Med Sea surface B Deep strains C O. tauri ITS 4 clades Data H. Moreau, Banyuls PFGE Cbp probe Pigments Strains isolated from depth possess a new type of Chl c Smallest eukaryote: 0.8 um 21 strains Surface vs Depth Étang de Thau Mediterranean Sea English Channel Atlantic Ocean Rodriguez et al. 2005
Photosynthetic picoeucaryotes Summary Few species described Important groups from cultures and environmental 18S : Prasinophyceae Prymnesiophyceae Cryptophyceae Heterokont classes : Dictyochophyceae, Pelagophyceae etc.. Prasinophyceae / Mamiellales Distribution of three genera begin to emerge
Photosynthetic picoeucaryotes Future directions Investigate more diverse environments Isolate representative of uncultivated groups Complement 18S by other approaches Biased primers Plastid 16S Populations sorted by flow cytometry Distribution of key groups FISH QPCR Investigate ecotypic differentiation Micromonas, Ostreococcus
Acknowledgments PICODIV F. Not F. Zhu F. Le Gall and F. Jalabert D. Scanlan and UW group R. Massana and Barcelona group W. Eikrem and Oslo group EU FP5 projects PicoDiv PRIR PicoManche Fondation CNRS Aventis PROOF BIOSOPE CPER GenoMer et Souchothéque GIS Génomique Marine CRB Ministère de la Recherche PICODIV