| Co-Investigator(Kenkyū-buntansha) |
TAGUCHI Takahiro Kochi Medical School, Department of Medicine, Research Associate, 医学部, 助手 (80127943)
HIRAI Hirohisa Kyoto University, Primate Research Institute, Associate Professor, 霊長類研究所, 助教授 (10128308)
HIRATA Mizuki Kurume University, Department of Medicine, Associate Professor, 医学部, 助教授 (70080629)
AGATSUMA Yoshiko Kochi Gakuen College, Department of Medical Technology, Professor, 衛生技術科, 教授 (50004726)
OKAMOTO Munehiro Tottori University, Department of Agriculture, Associate Professor, 農学部, 助教授 (70177096)
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| Research Abstract |
1. Nucleotide sequences of CO1, 28S and ITS2 were examined for samples from four species of the S.indicum group, Schistosoma indicum, S.spindale, S.nasale, S.incognitum collected from Bangladesh, Indonesia, Sri Lanka and Thailand, respecitively, and the NJ, UPGMA and Parsimony methods were used for phylogenetic analyses. The following results were obtained ; l)S.indicum and S.spindale were closely related to S.haematobium from Africa and to each other, while S.nasale has affinity with S.mansoni. 2) S.incognitum lies distant from the cluster that includes other three species of the S.indicum group and the African species. 2. A elephant schistosomes, Bivitellobilharzia nairi that belonged to the genus Schistosoma formerly, was found to show affinity to the Schistosoma species in a molecular level as well. 3. Nucleotide sequences of snail hosts in Sri Lanka and Bangladesh, I.exustus and Lymnaea spp., were also analyzed for the ITS2 and 28S regions, and found that I.exustus has a stronger affinity to Biomphalaria spp. than to Lymnaea spp. 4. Chromosomal analysis for the C-banding pattern showed that seven pairs of autosomes and sex chromosomes (Z and W) were species-specific, and large differences exist between Asian and African species of Schistosome. In particular, findings of AM inversion of chromosome 2 suggests that S.japonicum in Asia is of original type, while the African species, of derived type. 5. As a hypothesis, 1) Ancestral species of Schistosoma was diverged from Bivitellobilharzia nairi in Asia tens of millions years ago, and produced two species complex group, the S.sinensium and S.indicum group. 2) The S.japonicum group arose from ancestral species of the S.sinensium, adapting a new snail host, Oncomelania. 3) Ancestral species of the S.indicum group, adapting to a new snail host, Indoplanorbis, migrated into the African continent due to an unknown way, and gave rise to ancestral species of the African species.
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