Mystery of the sex determination in the freshwater jellyfish, Craspedacusta sowerbii

2019 Fiscal Year Final Research Report

• Project/Area Number: 16K07377
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Developmental biology
• Research Institution: Nara Medical University
• Principal Investigator: Kobayashi Chiyoko 奈良県立医科大学, 医学部, 講師 (20342785)
• Co-Investigator(Kenkyū-buntansha): 蛭田 千鶴江 北海道大学, 理学研究院, 研究院研究員 (20723018) ; 鈴木 隆仁 滋賀県立琵琶湖博物館, 研究部, 学芸員 (60771285)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: 性決定 / 生活環 / 発生

Outline of Final Research Achievements

The freshwater jellyfish, Craspedacusta sowerbii, belong to the class Hydrozoa, the order Limnomedusae, and one of the few members of the phylum Cnidaria to colonize freshwater successfully. The medusae of C. sowerbii often appear to be monosexual. Therefore, in this study, we aimed to clarify whether the sex of the C. sowerbii is determined genetically or by environmental factors, by reproducing the entire life cycle of the C. sowerbii in the laboratory. As a result of observing the medusa maturation process in the laboratory, young medusa formed from polyps from different ponds of different sexes matured to different sexes. Therefore, it is considered that there is a high possibility that the sex is already present at the polyp stage, that is, the sex of the C. sowerbii is genetically determined.

Free Research Field

発生生物学

Academic Significance and Societal Importance of the Research Achievements

マミズクラゲの全生活史を実験室で再現した研究室は当研究室が世界でも初めてであると自負している。つまりマミズクラゲ発見当初から不思議とされていた３つの謎（芽体形成、性決定、生物伝播）の解明に迫れる条件が整った。またマミズクラゲは発生学、生態学を含めて様々な角度から研究できる材料であることから、マミズクラゲをモデルとした刺胞動物の発生進化生態学を含む複合的理解が可能となる。