A chitinous membrane as a defense system against microorganisms in the intestine of teleost species

2022 Fiscal Year Final Research Report

• Project/Area Number: 19H03042
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 40040:Aquatic life science-related
• Research Institution: The University of Tokyo
• Principal Investigator: Watanabe Soichi 東京大学, 大学院農学生命科学研究科(農学部), 准教授 (20507884)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 魚類 / 生体防御 / 腸管 / キチン

Outline of Final Research Achievements

We demonstrated that chitin synthase in teleost species can synthesize chitin, and homologues of chitin synthase are widely conserved among Actinopterygii. Also, we found the intestinal chitinous membrane in various fish species. The pore size of chitinous membrane in the fish intestine is around 100 nm, which is fine enough to function as a barrier against bacteria. These findings strongly suggest that the intestinal chitin-based defense system against bacteria is universal among ray-finned fishes. We also determined that the chitin synthase protein is localized at the apical brush-border membrane of the intestinal epithelial cells in teleost fish, and identified several genes involved in the synthesis pathway of UDP-GlcNAc, a substrate of chitin synthase, specifically expressed in the intestinal epithelia.

Free Research Field

魚類生理学

Academic Significance and Societal Importance of the Research Achievements

本研究の成果は魚類の腸管においてキチン膜による生体防御機構が普遍的に存在することを強く示唆するものであり、腸内細菌叢の動態等を理解する上で極めて重要な知見をもたらした。また、脊索動物門の生物が機能的なキチン合成酵素を持つことを明確に示した報告はこれまでになく、これまで無脊椎動物に限られると考えられてきた内因性キチンの役割を脊索動物門に対象を広げて検討することを求める成果であることから、その学術的意義は大きい。今後、魚類腸管内キチン膜による生体防御機構の詳細をさらに明らかにすることで、魚類養殖での疾病対策技術につなげることもできると考えられる。