Jellyfish oocyte maturation triggered by light or dark stimulus

2021 Fiscal Year Final Research Report

• Project/Area Number: 17K07482
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Animal physiology/Animal behavior
• Research Institution: Miyagi University of Education
• Principal Investigator: Deguchi Ryusaku 宮城教育大学, 大学院教育学研究科高度教職実践専攻, 教授 (90302257)
• Project Period (FY): 2017-04-01 – 2022-03-31
• Keywords: 卵母細胞 / 放卵 / 神経ペプチド / 生殖隔離

Outline of Final Research Achievements

There exist light (L)-type and dark (D)-type medusae, in which oocyte maturation and spawning occur in response to light stimulation (light after dark) and dark stimulation (dark after light), respectively, in the hydrozoan jellyfish Cladonema pacificum. The present study provides evidence that RPRPamide or related peptides released from the gonad epithelium functions as maturation-inducing hormone in both types. The F1 hybrids obtained from heterotypic crossings could spawn in response to both light and dark stimulations, although stronger changes in light intensity were necessary for the spawning of F1 hybrids. Interestingly, the F2 generation that inherits either or both of F1 hybrid chromosome sets failed to metamorphose into polyps. These data, together with the results of molecular phylogenetic analysis using DNA sequences, support the idea that reproductive isolation has been established between L- and D-type C. pacificum, which might be regarded as separate species now.

Free Research Field

動物発生学

Academic Significance and Societal Importance of the Research Achievements

原始的な動物であるクラゲでは、光環境の変化に応じて卵成熟およびそれに続く放卵が起こることが知られていたが、真逆の刺激（明刺激と暗刺激）に反応するクラゲの比較解析が行われたのは本研究が初めてである。得られた結果は新規性が高く、動物における卵成熟機構の「進化」や「原型」の理解を促すものである。また、全国的に人気のある水族館でのクラゲ展示などにも影響を与える重要な成果であると考えている。