Studies on biodiversity and origins of freshwater dinoflagellates.

这个项目的目的是；1)调查日本淡水鞭毛藻物种的生物多样性；2)利用分子技术分析这些物种之间的系统发育关系；3)调查淡水鞭毛藻的起源；4)重新评估现有的分类系统。我们在北海道周边和其他地区采集了大量的水样。到目前为止，我们已经鉴定了大约70种鞭毛藻，其中我们获得了大约50种鞭毛藻的SSU rDNA序列，并利用这些序列研究了系统发育关系。我们相信我们能够揭示主要生活在寒温带地区的淡水鞭毛藻的生物多样性。分子系统发育研究表明：1)大属如Gymnodinium、gyyorodinium、Amphidinium、Peridinium、Peridiniopsis是多系的；2)gyrodinium可以通过圆形的顶端凹槽和纵向条纹来定义；3)Cystodinium可能与Woloszynskia有关；4)在Peridinium/Preidiniopsis复合体中，包囊形态和表面纹饰反映了系统发育；5)所有具有钩体的物种可能是单系的；6)部分woloszynskoid与共生的鞭毛藻有关。即,Symbiodiniium。在本项目中，我们建立了适合的单细胞PCR和单细胞SEM方法，这些技术必将有助于进一步研究和了解原生生物多样性。

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.