【博士論文】学術データベース

博士論文 / Comparative genomic studies on Dicyema japonicum: the phylogenetic position of dicyemids and the genomic adaptations to parasitic lifestyle ニハイチュウの比較ゲノム科学的研究:系統発生学的位置および寄生虫生活へのゲノム適応

書誌事項

タイトル

Comparative genomic studies on Dicyema japonicum: the phylogenetic position of dicyemids and the genomic adaptations to parasitic lifestyle

タイトル別名

ニハイチュウの比較ゲノム科学的研究:系統発生学的位置および寄生虫生活へのゲノム適応

学位授与大学

Okinawa Institute of Science and Technology Graduate University

取得学位

Doctor of Philosophy

学位授与番号

甲第20号

学位授与年月日

2018-08-31

注記・抄録

Parasitism has independently occurred more than 200 times across 15 animal phyla, yet remains a topic of debate how free-living ancestors evolved to parasitic organisms. Dicyemid mesozoans are microscopic endoparasites inhabiting the renal sacs of some cephalopods. They possess simplified body architecture without differentiated organs and have long fascinated biologists because of their incompletely known lifecycles. Obtaining genomic data from enigmatic parasites would be essential to better comprehend parasitism evolution. Here I decoded the genome of Dicyema japonicum which is approximately 68 Mbp with extraordinarily shortened introns. Comparing among bilaterians, D. japonicum retains fewer genes in most KEGG pathways, as in the case of four parasite species from different phyla that shows a convergent gene number reduction in the metabolism pathways. In contrast, D. japonicum exhibits multi-copy gene clusters associated with endocytosis and membrane trafficking, perhaps reflecting its specialized nutrient-uptake strategy. Up-regulated transcripts at dispersal larvae stage present over-representation on gene ontology terms of motor activity and response to the stimulus. The occurrences of neurotransmitters and neuropeptides on apical cells of dispersal larva was evident. Taken together, dicyemids may utilize potential sensory functions to detect the environmental cues and could actively approach new hosts. In summary, the dicyemid genome provides a resource to uncover mysterious lifecycle of dicyemids, as well as studying comparative genomics to gain insights into the parasitism evolution. Furthermore, genomes of parasites may adapt through eliminating genes which are not necessary for parasitic lifestyle or increasing gene copies corresponding to lineage-specific biological processes.

元資料の権利情報 : © 2018 The Author

各種コード

NII論文ID(NAID)

500001080989

DOI

info:doi/10.15102/1394.00000642

本文言語コード

eng

データ提供元

NDLデジタルコレクション

DOI

博士論文 / 沖縄科学技術大学院大学 / 哲学

博士論文 / 沖縄科学技術大学院大学

博士論文 / 哲学

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