In most fish, reproduction is seasonal or periodic under the suitable conditions. In turbot (Scophthalmus maximus) farms, one of the most economically important marine flatfish species, changes in daylength could cause changes in the spawning time. In this study, to characterize the regulation of reproductive physiology following light signals, three melatonin receptors (Mtnr) investigated in turbot were named smMtnr1, smMtnr2, and smMtnr1c. Distinct expression profiles demonstrated that Mtnr mRNAs were concentrated in the brain (as detected in the hypothalamus (Hy) and mesencephalon (Me)), gonad and eye. The most abundant Mtnr1 and Mtnr2 mRNA expression levels were detected in the central nervous system at the beginning of the breeding season, suggesting that Mtnr1 and Mtnr2 may play vital roles in the regulation of turbot gonadal development. In addition, the melatonin profiles gradually increased and reached to the highest level at the spawning stage, indicating that melatonin is a potent hormone in the regulation of fish oocyte growth and maturation. The results of this study suggested that melatonin is the primary factor that transduces the light signal and regulates the physiological functions of turbot seasonal reproduction. Moreover, the results of this study may establish a foundation for further research seeking to identify fish melatonin receptors involved in the gonadal development and gamete maturation.

Chunyan Zhao;Shihong Xu;Yifan Liu;Chengcheng Feng;Yongshuang Xiao;Yanfeng Wang;Qinghua Liu;Jun Li

School of Marine Science and Engineering,Qingdao Agricultural University,Qingdao 266109,China;Key Laboratory of Experimental Marine Biology,Centre for Ocean Mega-Science,Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,China;Marine Biology and Biotechnology Laboratory,Pilot National Laboratory for Marine Science and Technology(Qingdao),Qingdao 266237,China;Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou),Guangzhou 511458,China

海洋学报（英文版）

[1]Chunyan Zhao;Shihong Xu;Yifan Liu;Chengcheng Feng;Yongshuang Xiao;Yanfeng Wang;Qinghua Liu;Jun Li-.Changes of melatonin and its receptors in synchronizing turbot (Scophthalmus maximus) seasonal reproduction and matura-tion rhythm)[J].海洋学报（英文版）,2022(01):84-98

turbot,matura,flatfish,daylength,Mtnr,smMtnr1,smMtnr2,smMtnr1c,mesencephalon,Mtnr1,Mtnr2

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