Application of fluorescent in situ hybridization coupled with tyramide signal amplification (FISH-TSA) to assess eukaryotic picoplankton composition
Résumé
Photosynthetic picoeukaryotes (phytoplankton cells with a diameter smaller than 2 to 3 mum) contribute significantly to both biomass and primary production in the oligotrophic open ocean and coastal waters, at certain times of the year. The identification of these organisms is difficult because of their small size and simple morphology, therefore hindering detailed ecological studies of their distribution and role, In this paper, we demonstrate the use of oligonucleotide probes specific to algal classes or to lower order taxa in combination with fluorescent in situ hybridization and tyramide signal amplification (FISH-TSA) to determine eukaryotic picophytoplankton diversity, Target cells were detected and enumerated using epifluorescence microscopy. The sensitivity of the technique and the specificity of the probes were tested on pure and mixed picoplanktonic strains, as well as on natural samples from the English Channel. In these samples, the community was dominated by cells belonging to the division Chlorophyta. Haptophyta, Bolidophyceae and Pelagophyceae were also detected at low abundance. The FISH-TSA method is readily applicable to the study of picoplankton diversity in natural communities.
Mots clés
fluorescent in situ hybridization
tyramide signal amplification
picoplankton
eukaryotes
coastal waters
diversity
TARGETED OLIGONUCLEOTIDE PROBES
16S RIBOSOMAL-RNA
WHOLE-CELL HYBRIDIZATION
2 OCEANIC REGIONS
IN-SITU
COMMUNITY STRUCTURE
BOLIDOPHYCEAE HETEROKONTA
PIGMENT COMPOSITION
FLOW-CYTOMETRY
HPLC ANALYSIS