Studies on biodiversity and origins of freshwater dinoflagellates.

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The aims of this project were ; 1)to investigate biodiversity of freshwater dinoflagellate species in Japan, 2)to analyze phylogenetic relationships between these species, using molecular technique, 3)to investigate the origin(s) of freshwater dinoflagellates, and 4)to re-evaluate the present taxonomic system. We have collected number of water samples around Hokkaido and from other area. So far, we have identified some 70 species of dinoflagellates Of these, we have obtained SSU rDNA sequences for about 50 species and have investigated phylogenetic relationships using these sequences. We believe we were able to reveal the biodiversity of freshwater dinoflagellates mainly inhabiting cold-temperate regions.The molecular phylogenetic studies revealed the followings ; 1)the large genera such as Gymnodinium, Gyorodinium, Amphidinium, Peridinium, Peridiniopsis are polyphyletic, 2)Gyrodiniuim can be defined by circular apical groove and longitudinal striae, 3)Cystodinium is probably related to the Woloszynskia, 4)in the Peridinium/Preidiniopsis complex, cyst morphology and surface ornamentation reflect phylogeny, 5)all the species possessing cleptoplastidy are probably monophyletic and 6)Some of the woloszynskoid are related to the symbiotic dinoflagellates, viz. Symbiodiniium.In this project, we have established suitable methods for single-cell PCR and single-cell SEM and these techniques will certainly contribute to further studies and understanding of protist diversity.