title: Eukaryotic picoplankton communities of the Mediterranean Sea in summer assessed by molecular approaches (DGGE, TTGE, QPCR).
abstract: The composition and abundance of eukaryotic picoplankton (defined here as cells smaller than 3 mum) was investigated in the Morocco upwelling and throughout the Mediterranean Sea in late summer using flow cytometry and molecular methods (gradient gel electrophoresis and quantitative PCR). The picoplankton displayed characteristics typical of oligotrophic oceanic areas with concentrations down to 1000 cells mL(-1) in the Eastern Basin. The most abundant eukaryotic sequences recovered by gradient gel electrophoresis were related to uncultivated marine groups: alveolates I (16%) and II (26%) and a newly discovered group (env Nansha, 17%) for which sequences have been recently obtained from the South China Sea and that could be related to Acantharians. Prasinophyceae (photosynthetic green algae) accounted for 10% of the sequences, whereas Cercozoa, Stramenopiles, Polycystinea, dinoflagellates and ciliates provided minor contributions. The use of quantitative PCR coupled with taxon-specific primers allowed us to estimate the relative abundance of several taxa belonging to the Prasinophyceae. Of the three genera assessed, Bathycoccus appeared as the most abundant, forming localized maxima at depth.
authors.affiliation: Station Biologique, UMR7144 CNRS et Université Pierre et Marie Curie, Roscoff, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Marie
authors.forename: Fei
authors.initials: F
authors.lastname: Zhu
authors.forename: Vanessa
authors.initials: V
authors.lastname: Balagué
authors.forename: Joséphine
authors.initials: J
authors.lastname: Ras
authors.forename: Daniel
authors.initials: D
authors.lastname: Vaulot
mesh_terms: D000818:Animals; D000460:Chlorophyta / Q000145:classification / Q000235:genetics; D016798:Ciliophora / Q000145:classification / Q000235:genetics; D004275:DNA, Ribosomal / Q000032:analysis; D017753:Ecosystem; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D005057:Eukaryotic Cells; D005434:Flow Cytometry; D008522:Mediterranean Sea; D008969:Molecular Sequence Data; D010933:Plankton / Q000145:classification* / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000379:methods; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012621:Seasons; D012623:Seawater / Q000382:microbiology / Q000469:parasitology; D017422:Sequence Analysis, DNA
chemical_list: D004275:DNA, Ribosomal; D012337:RNA, Ribosomal, 18S