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

本项目的目的是研究在甲藻中发现的眼斑的结构多样性，以及基于分子系统发育数据对甲藻谱系中眼斑的获得和损失的系统发育考虑。在日本各地调查的Mamy物种中，仅发现蛋白核拟裸藻、Hexraecingula和Scrippsiella sp.含有眼斑。对这些眼罩进行了超微结构观察。结果表明，这三个物种都具有相同类型的眼斑，即眼斑是叶绿体的一部分，由两排脂球组成。到目前为止所描述的眼点只有一排脂球，这是该类型的首次报道。对9个种的18SrDNA进行了测定和分析。从DDBJ获得的25种数据被纳入分析范围。结果表明，它们主要由三个分支组成，即原甲藻类群、共生藻类群和PPG(原甲目、周围目、裸甲目)复合体。带有眼斑的甲藻被包含在PPG复合体中。在这两个带眼斑病的物种中，蛋白核拟青霉和六角斑潜蝇关系密切，不同类型眼斑的斑潜蝇也是PPG复合体的一员。结果表明，原来的眼斑从未分裂，而是在细胞质的某处重新形成的。未来将需要进行超微结构水平的研究。

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..