Molecular basis of the hagfish osmoregulatory strategy

2023 Fiscal Year Final Research Report

• Project/Area Number: 19K16178
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 44040:Morphology and anatomical structure-related
• Research Institution: Shimane University
• Principal Investigator: Yamaguchi Yoko 島根大学, 学術研究院農生命科学系, 助教 (70801827)
• Project Period (FY): 2019-04-01 – 2024-03-31
• Keywords: 円口類 / ヌタウナギ / 体液調節 / 内分泌系

Outline of Final Research Achievements

Vertebrates possess a remarkable ability to maintain body fluid balance. However, the origine and evolution of osmo- and iono-regulatory machinaries remain poorly understood. In the present study, we focused on hagfishes, which are characterized by omo- and iono-conforming nature. Combining in vivo salinity transfer experiment and RNA-Seq analysis, we explored the molecular mechanisms underlying the unique body fluid homeostasis of hagfishes. For most of the known vertebrate osmoregulatory genes, their counterparts were found in the hagfish genome; however, some of these hagfish genes, including the genes encoding conventional salt transporters, are silenced. Therefore, the unique body fluid composition of hagfishes is most likely attributable to the distinct regulation, rather than the repertoire, of osmoregulatory genes. This consequently suggests that the ability to maintain body fluid balance was secondarily lost in the hagfish lineage.

Free Research Field

比較生理学、比較内分泌学

Academic Significance and Societal Importance of the Research Achievements

本研究の結果は、我々の体液調節能力の起源が従来考えられていたよりも古いことを示唆する。このように、ヌタウナギは脊椎動物の進化を考える上で鍵を握る生物であり、近年注目を集めている。しかし現生種の大半が深海性のため捕獲・飼育が難しく、研究はきわめて遅れている。今回は、①例外的に浅海に分布する種をモデルとし、②同種が容易に捕獲できる島根県の地の利を生かし、③分子レベルで大規模かつ網羅的な解析を行うことにより、ヌタウナギの生理学研究を大きく押し進めることができた。得られたデータは公開データベースに登録したため、今後、国内外の研究者に活用されることが期待される。