Testis development in the Japanese eel is affected by photic signals through melatonin secretion

PeerJ

article

Ji-Yeon Hyeon¹  Jun-Hwan Byun¹  Eun-Su Kim¹  Yoon-Seong Heo⁴  Kodai Fukunaga⁵  Shin-Kwon Kim⁶  Satoshi Imamura³  Se-Jae Kim²  Akihiro Takemura⁷  Sung-Pyo Hur¹ 

[1] Jeju Marine Research Center, Korea Institute of Ocean Science and Technology;Department of Biology, Jeju National University;Graduate School of Engineering and Science, University of the Ryukyus;LED-Marine Biology Convergence Technology Research Center, Pukyong National University;Center for Strategic Research Project, University of the Ryukyus;Aquaculture Research Division, National Institute of Fisheries Science;Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus;Department of Ocean Science, University of Science and Technology

关键词: Japanese eel;    Melatonin;    Moonlight;    Eel migration;    Photoperiod;    Photic signal;   

DOI  :  10.7717/peerj.12289

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

ObjectiveAccording to reported spawning characteristics of Japanese eel, Anguilla japonica, which exhibit spawning and migration patterns that are synchronized with lunar cycles and photoperiod, we hypothesized that a close association exists between specific photic signals (daylight, daylength, and moonlight) and endocrinological regulation. Given the photic control in melatonin secretion, this hypothesis was tested by investigating whether melatonin signals act as mediators relaying photic signals during testis development in the eel.MethodsWe examined changes in melatonin-secretion patterns using time-resolved fluorescence immunoassays in sexually immature and mature male Japanese eels under the condition of a new moon (NM) and a full moon (FM).ResultsThe eye and plasma melatonin levels exhibited a nocturnal pattern under a 12-h light: dark cycle (12L12D) or under constant darkness (DD), but not with constant light (LL). Eye melatonin levels were similar under the 12L12D and short-day (9L15D) conditions. In the long-day condition (15L9D), secreted plasma melatonin levels were stable, whereas short-day melatonin secretion began when darkness commenced. Sexual maturation began at 8 weeks following intraperitoneal injection of human chorionic gonadotropin (hCG), and NM exposure led to significantly higher eye and plasma melatonin levels compared with those detected under FM exposure.

【 授权许可】

CC BY