2021 Fiscal Year Final Research Report
Dietary diversity and speciation of Limnoria (Limnoriidae, Isopoda) and adaptation of digestive enzyme system
| Project/Area Number |
19K06822
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 45030:Biodiversity and systematics-related
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| Research Institution | Chiba University |
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Principal Investigator |
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| Project Period (FY) |
2019-04-01 – 2022-03-31
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| Keywords | Limnoria / Limnoriidae / Isopoda / 食性転換 / 種分化 / 消化酵素 |
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| Outline of Final Research Achievements |
Limnoria (Isopoda) is one of the few metazoans that can decompose wood and cellulose using enzymes encoded by its own genes. In this study, I collected brown algae-eating Limnoria throughout Japan, and performed phylogenetic analysis, species delimitation analysis, ancestral distribution estimation, and RNA-seq of digestive enzymes.
Phylogenetic analysis and SDA revealed that they diverged into three clades corresponding to food habits and differentiated into 8 MOTUs. The algal host and the distribution area of the branch points were estimated. The common ancestor of brown algae-eating Limnoria was the generalist that live in the Pacific Ocean. The specialist clades feeding on the specific algae are diverged first. Then, diversification occurs by distribution area.
RNA-seq analysis of digestive enzymes clarified that hemocyanin is expressed very high, and that GH7 and GH16 were highly expressed among the CAZymes. High expression level of GH16 may be the adaptation to digest laminaran.
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| Free Research Field |
多様性生物学
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| Academic Significance and Societal Importance of the Research Achievements |
褐藻食キクイムシはこれまで1種しか知られていなかったが，本研究により新たに2種類が記載され，さらに6種が未記載である可能性が示された．これは海生等脚類の多様性の認識に大きく貢献できる．
また，特定の海藻への特化と，地理的隔離による褐藻食キクイムシの多様化の仕組みを明らかにしたことにより，海洋生物の進化要因の解明に大きく貢献した．
褐藻食キクイムシの消化酵素の解析は，食性転換の仕組みの解明に貢献し，バイオ燃料開発などの応用研究の基礎となることが期待される
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