STUDIES OF BIODIVERSITY ON PROTOZOAN ENDOSYMBIOTIC DIATOMS

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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.