2019 Fiscal Year Final Research Report

Somatic cell epigenetics and gonadal sexual plasticity in fish

Research Project

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Project/Area Number	16H04981
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	一般
Research Field	Aquatic life science
Research Institution	Kyushu University
Principal Investigator	OHTA KOHEI 九州大学, 農学研究院, 准教授 (10585764)
Co-Investigator(Kenkyū-buntansha)	Mohapatra Sipra 愛媛大学, 南予水産研究センター, 助教(特定教員) (80715441) C Tapas 愛媛大学, 南予水産研究センター, 助教(特定教員) (70715440) 長濱嘉孝基礎生物学研究所, 名誉教授 (50113428) 松原孝博愛媛大学, 南予水産研究センター, 教授 (60443389)
Project Period (FY)	2016-04-01 – 2019-03-31
Keywords	性的可塑性 / エピジェネティクス / 魚類 / 生殖腺 / 生殖幹細胞 / 性転換
Outline of Final Research Achievements	To understand the molecular and cellular mechanisms of gonadal sexual plasticity, the epigenetic regulation and the origins of newly formed gonadal cells during sex change were investigated. By using the wrasse, we found the presence of germline stem cells (GSCs) in both ovary and testis. Additionally, undifferentiated somatic cell (SSC) candidates were isolated. These GSCs and SSCs may collaboratively co-ordinate the origin of testicular tissue during sex change from females to males. Interestingly, these cells were also identified in the gonochoristic species, such as the Japanese anchovy and medaka highlighting that the cellular mechanism is conserved to some extent in fish. On the other hand, together with various sex specific genes and steroidogenic enzymes, the genes responsible for epigenetic modifications changed drastically in association with the gonadal change from ovary to testis, suggesting that the epigenetic changes are involved in the gonadal sexual plasticity.
Free Research Field	魚類生殖学
Academic Significance and Societal Importance of the Research Achievements	我々の構築したモデル実験系を用いて、生殖細胞系列と体細胞系列の2種の幹細胞が性転換魚と雌雄異体魚の雌雄の生殖腺（卵巣と精巣）に共通して存在することを見出すと共に、生殖腺体細胞で発現する性特異的遺伝子のDNAメチル化パターンに性差が認められること、性転換に伴いステロイド代謝酵素、性特異的因子、およびエピジェネティクス関連因子の各遺伝子群が著しい発現変動を示すことを明らかにした。こうした成体生殖腺の性的可塑性に関わる遺伝子、細胞、エピジェネティクスの基盤情報は、魚類を含む脊椎動物一般の性的可塑性の分子・細胞機構の研究に寄与するのみならず、水産における新たな性統御法や細胞操作技術の開発に貢献する。