1. Genetic diversity of eukaryotic picoplankton in Astan (Roscoff) by SSU rRNA gene cloning and sequencing Khadidja Romari, Fabrice Not & Daniel Vaulot Station biologique de Roscoff

2. DNA extraction Extracted nucleic acid PCR Amplified rDNA Cloning rDNA clones Sequencing Phylogenetic identification rDNA sequences  Comparative sequence analysis rDNA database Environmental sample (pre-filtration and filtration)

3. PCR on the white colonies M M 1 2 3 4 5 6 7 8 9 10 11 12 . . . . . . . . . . . 1800 bp Fig.1: Agarose gel electrophoresis showing 18S rDNA PCR product of clones from environmental sample (RA000412). M: Smart Ladder Librarie clones screening

4. RFLP : Restriction Fragment Lenght Polymorphism 600 bp Fig.2: Agarose gel electrophoresis showing the restriction profiles of 18S rDNA fragment of clones environmental sample(RA000412) obtained using the enzyme HaeIII. M’: molecular mass marker 100bp M’ M’ M’ 1 2 3 5 6 8 9 10 11 12

5. Alveolata Perkinsea Fungi Neighbor-joining dendrogram of the picoeukaryote groups found in the four libraries

6. Clones Distribution of the picoeukaryote groups during the four seasons Ex: RA000412 = station of the cruise, year, month, day

7. Photosynthetic group Heterotrophic group April 2000 December 2000

8. Alveolata Perkinsea Fungi Neighbor-joining dendrogram of the picoeukaryote groups found in the four libraries clones 

9. 0.10 Part of tree extracted from ARB indicating a position of the He000427.214 group

10. SSU rDNA phylogenetic relationshipps (Parcimony ML tree) between 13 clones of He000427.214 group

11. Alveolata Perkinsea Fungi Neighbor-joining dendrogram of the picoeukaryote groups found in the four libraries clones 

12. 0.10 Part of tree extracted from ARB indicating a position of the LKM 74 group

13. SSU rDNA phylogenetic relationshipps (Parcimony ML tree) between 13 clones of LKM 74 group

14. Alveolata Perkinsea Fungi Neighbor-joining dendrogram of the picoeukaryote groups found in the four libraries clones 

15. Part of tree extracted from ARB, indicating a position of the clone RA000609.30

16. Conclusion • The phylogenetic diversity in each library was rather large • Low redundancy • Of a total of 224 eukaryal clones, 85 affiliated with algal class and 79 • clones are affiliated with clearly heterotrophic group • The spring clone library is largely dominated by the phototrophic • group : Prasinophyte and chryptophyceae

17. Conclusion • Some sequences are found identical in both Helgoland and Roscoff • clone libraries • Two novel group appeared : • He000427.214 (13 clones) • LKM 74 (9 clones)