STUDIES OF BIODIVERSITY ON PROTOZOAN ENDOSYMBIOTIC DIATOMS

从放射虫和有孔虫宿主中分离出内生硅藻并进行培养。鉴定到的硅藻有Nitzschia sp.、Entomoneis sp.；底栖大有孔虫目的Nanofrustulum shiloi、Sorites orbiculus和浮游有孔虫目的Amphora roettgeri、Globigerina sp.；褐球藻目的内共生硅藻为Minutocellus polymorphus，并通过透射电镜和扫描电镜对其进行了详细观察。18S rDNA分析表明，M. polymorphs与Cymatosira和Papilocellulus （cymatosiaceae的形态学成员）形成单系，并培养了另一种Globigerina sp.的共生藻类，并用TEM进行了观察。在细胞纤维结构上与亚绿球藻相似，但在18S rDNA分析上与calceolata球藻相似。探讨了藻类向体内放射虫细胞转化的途径。研究了刺虫属和纳塞拉属放射虫属与内共生菌的相对大小、有无放射虫壳开口以及开口的大小。此外，还研究了从热带海域流出的日本海流沿岸的异域植物群的多样性，因为它是共生体的重要来源。选择Shikine岛和琉球群岛作为研究区域，进行了两年多的研究。

Endosymbiotic diatoms were isolated from radiolarian and foraminiferan hosts and cultured. Diatoms identified were Nitzschia sp., Entomoneis sp. Nanofrustulum shiloi from benthic larger foraminifera, Sorites orbiculus, and Amphora roettgeri from planktonic foraminifera, Globigerina sp. Endosymbiotic diatom from Sphaerozoum fuscum was Minutocellus polymorphus and observed in detail with transmission and scanning electron microscopy. It was clarified in the analysis of 18S rDNA, that M. polymorphs formed monophyly with Cymatosira and Papilocellulus, which are morphological members of Cymatosiraceae, Symbiotic alga isolated from another Globigerina sp. was cultured and examined by TEM. It was coccoid Pelagophyceae and similar to Pelagococcus subviridis in cellural fien structure but to Pelagococcus calceolata in the analyses of 18S rDNA.We explored transformation route of algae to radiolarian cell inside. Radiolarian species of Spumellaria and Nassellaria were studied regarding relative size to endosymbionts, presence or absence of the opening of radiolarian shell and the size of the opening. Moreover, the diversity of distom flora along the Japan Current flowing from tropical sea area was studied, since it is important for the source of symbionts. Shikine Island and Ryukyu Islands were chosen as study area an researches were performed over two years.