Research on the dinoflagellate eyespot-their diversity, division mechanisms and origins-.

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The purpose of this project was to study structural diversity of the eyespot found in dinoflagellates and phylogenetic consideration of obtainings and losses of eyespots in dinoflagellate lineages based on molecular phylogenetical data. To study dividing mechanism seen in Dinothrix paradoxa was also included in the aims of the project.Of the mamy species investigated from various parts of Japan, only Gymnodinium pyrenoidosum, Scrippsiella hexpraecingula and Scrippsiella sp.have been found to contain the eyespot. These eyesposts were investigated ultrastructurally. It was revealed that all three species possess same type of the eyespot, i.e.the eyespot is part of the chloroplast, consisting of two rows of lipid globules. The eyespots hitherto described only had single row of the lipid globules and thust this is the first report of this type.Phylogenetic relationships of dinoflagellates was investigated. The 18SrDNA of 9 species was determined and analyzed. 25 species of data from DDBJ were included in the analyzes. The results revealed that there are three main clades, i.e.Gonyaulax-group, Symbiodinium-group and PPG(Prorocentrales, Peridiniales, Gymnodiniales)-complex. The dinoflagellates with the eyespot were included in the PPG-complex. Of these two eyespot-bearing species, G.pyrenoidosmu and S.hexapraecingula were found to be closely related.Dinothrix paradoxa with different type of eyespot was also found to be a member of PPG-complex.The division process of the eyespot of Dinothrix paradoxa was investigated light microscopically. It was revealed that the original eyespot never divided and the eyespot was formed de novo somewhere in the cytoplasm. The ultrastructural level investigations would be needed in future..