| Co-Investigator(Kenkyū-buntansha) |
TABUCHI Norihiko Fukuyama University, Faculty of Pharmacy and Pharmaceutical Sciences, Research Associate, 薬学部, 講師 (60330685)
MITANI Harumi Fukuyama University, Faculty of Pharmacy and Pharmaceutical Sciences, Research Associate, 薬学部, 助手 (30330690)
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| Research Abstract |
The gene content of a mitochondrial (mt) genome is usually conserved in Metazoa. In contrast, the re-arrangement of these genes, 37 genes and large noncoding region (LNR), was observed in chigger mites of the genus Leptotombidium. Recombination of theses genes, relocation in even different direction, and gene duplication were also occurred substantially in the other acariformes mite (Ascoschoengastia sp. and Walchia hayashii). We found that the mt genome of Leptotrombidium pallidum has an extra gene for large-subunit rRNA (rrnL), a pseudo-gene for small-subunit rRNA (PrrnS), and three extra LNRs, additional to the 37 genes and an LNR typical of Metazoa. Further, the arrangement of mt genes of L. pallidum differs drastically from that of the hypothetical ancestor of the arthropods. To find to what extent the novel gene content and gene arrangement occurred in Leptotrombidium, we sequenced the entire mt genomes of four other species, L.akamushi, L.deliense, Ascoschoengastia sp., and Walchia hayashii, and partially L.fletcheri, L.scutellare, L.intermedium, L.chaingraiensis, L.imphalum, L.fujii, and Leptotrombidium sp. The mit genomes of Ascoschoengastia sp. and W.hayashii were entirely distinct structures from that of Leptotrombidium. The other Leptotrombidium species share the or partial arrangement of all genes with L. pallidum, except trnQ (for tRNA-glutamine). Unlike L.pallidum, however, these other species do not have extra rrnL or PrrnS and have only one extra LNR. By comparison between Leptotrombidium species and the ancestor of the arthropods, we propose that (1) the type of mt genome present in L.pallidum evolved from the type present in the other three Leptotrombidium species, and (2) three molecular mechanisms were involved in the evolution of mt gene content and gene arrangement in Leptotrombidium species.
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