2006 Fiscal Year Final Research Report Summary
Studies on diversity and origins of parasitic dinoflagellates.
| Project/Area Number |
16370039
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Biodiversity/Systematics
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| Research Institution | Hokkaido University |
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Principal Investigator |
HORIGUCHI Takeo Hokkaido University, Faculty of Science, Associate Professor, 大学院理学研究院, 助教授 (20212201)
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| Co-Investigator(Kenkyū-buntansha) |
OHTSUKA Susumu Hiroshima Univ., Grad.School of Biosphere Science, Professor, 大学院生物圏科学研究科, 教授 (00176934)
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| Project Period (FY) |
2004 – 2006
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| Keywords | dinoflagellate / parasitism / Marine Alveolate Group / ultrastructure / molecular phylogeny / biodiversity / protist / environmental clone sequence |
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| Research Abstract |
Little studies on parasitic dinoflagellates have been undertaken in Japan. The aims of this research are, therefore, 1)to understand species diversity of parasitic dinoflagellates around the Japanese coastal waters and 2)to understand their origins and their phylogenetic affinities with other dinoflagellates based on molecular phylogenetic analyses. In summary, we were able to recognize 8 species of parasitic dinoflagellates from various localities of Japan, belonging to 5 genera. These include, Blastodinium, Oodinium, Amoebophrya, Syndinium and Duboscquella. We have investigated each species with the aid of light and transmission electron microscopes. Also we have analyzed SSU rDNA sequences of these species using single cell PCR technique. Our molecular trees suggested that Blastodinium and Oodinium had originated from typical dinoflagellates, while Amoebophrya and Syndiniuim belong to the clade named Marine Alveoalte Group II. The marine protist parasitizing tintinnid ciliate, Favella ehrenbergii was identified as Duboscquella aspida. We found that this organism was included in the clade named, Marine Alveolate Group I (MAG-I). The latter clade has been recognized as assemblage of only environmental clone sequences originated from picoplanktonic size fractions and no actual organisms belonging to this clade have been identified (Although parasites of radiolarians have been found to belong this clade recently, their morphology has not been investigated. Dolven et al. 2007). Our finding, therefore, is the first organismal identification of the member of this enigmatic clade. The facts that environmental clone sequences of MAG-I have been detected almost anywhere in the ocean and members of the MAG-I mainly consists of parasites of radiolarians or ciliates suggest that the oceanic environments are full of (motile cells of) these parasites. Our research suggested importance of parasitism in the marine ocean ecology.
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