WHERE DID GAMETE DUCTS OF TELEOSTS COME FROM?

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K06738
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 44040:Morphology and anatomical structure-related
• Research Institution: Nagoya University
• Principal Investigator: KANAMORI AKIRA 名古屋大学, 理学研究科, 講師 (40324389)
• Co-Investigator(Kenkyū-buntansha): 木下 政人 京都大学, 農学研究科, 准教授 (60263125)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: ミュラー管 / ウォルフ管 / 真骨魚 / 全ゲノム倍化 / 配偶子輸送管 / 体腔上皮 / WNT / wnt4

Outline of Final Research Achievements

In most vertebrates, oviducts are derived from Mullerian ducts, and sperm ducts are derived from Wolffian ducts. However, in teleosts, genital ducts are formed within the gonads. Even with their drastic differences in morphology, could teleost genital ducts be simply transformed Mullerian ducts?
Wnt4 is one of the essential genes for Mullerian duct formation in mammals. Therefore, we examined phenotypes of two wnt4 homologs, wnt4a and 4b mutants, in medaka. In wnt4a mutants, the posterior region of the gonads stopped elongation and remained within the coelom in both males and females; there were no genital ducts, which, in wildtype, elongate on ventral side of the urinary bladder, did not form. The results suggest possibility that teleosts have evolved unique genital ducts utilizing the genetic network involved in Mullerian duct formation present in common ancestors between teleosts and mammals.

Free Research Field

発生生物学　進化生物学　生殖生物学　遺伝学

Academic Significance and Societal Importance of the Research Achievements

進化の過程ではドラスティックな形態の変化が多々見られるが、注意深く調べて行くとそれまでの遺伝子ネットワークを巧妙に利用していることがわかることもある。本研究では真骨魚（teleost）にのみ見られる配偶子輸送管の形成に、他の脊椎動物のミュラー管の形成過程で重要なwnt4が関わっていることを明らかにし、新しい形態形成機構の進化機構に重要な知見を得たといえる。