Characterization and differential expression of three GnRH forms during reproductive development in cultured turbot Schophthalmus maximus

Turbots (Schophthalmus maximus), one of the most important economic marine flatfish species, fail to undergo final spawning and spermiation naturally under artificial farming conditions. In vertebrates, reproduction is regulated by the brain-pituitary-gonadal axis (BPG-axis), and gonadotropin releas...

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Bibliographic Details
Published in:Journal of Oceanology and Limnology
Main Authors: Zhao Chunyan, Xu Shihong, Feng Chengcheng, Liu Yifan, Yang Yang, Wang Yanfeng, Xiao Yongshuang, Song Zongcheng, Liu Qinghua, Li Jun
Format: Report
Language:English
Published: SCIENCE PRESS 2018
Subjects:
turbot
GnRH
brain
gonad
reproductive development
Marine & Freshwater Biology
Oceanography
Limnology
GONADOTROPIN-RELEASING-HORMONE
SEABREAM SPARUS-AURATA
BASS DICENTRARCHUS-LABRAX
SCOPHTHALMUS-MAXIMUS
BARFIN FLOUNDER
GILTHEAD SEABREAM
MOLECULAR-CLONING
MESSENGER-RNA
OVARIAN MATURATION
MAMMALIAN GNRH
Scophthalmus maximus
Turbot
Online Access:http://ir.qdio.ac.cn/handle/337002/159854
https://doi.org/10.1007/s00343-018-7068-y
Description
Summary:Turbots (Schophthalmus maximus), one of the most important economic marine flatfish species, fail to undergo final spawning and spermiation naturally under artificial farming conditions. In vertebrates, reproduction is regulated by the brain-pituitary-gonadal axis (BPG-axis), and gonadotropin releasing hormone (GnRH) is one of its key components. Therefore, to better understand the physiology of reproduction in the turbot, three of the genes encoding GnRH subtypes-sbGnRH, cGnRH - II and sGnRH - were cloned and sequenced by isolating the cDNA sequences. The localizations and patterns of expression of their mRNAs were also evaluated during seasonal gonadal development. All three mRNAs were expressed abundantly in the brain; sbGnRH and sGnRH mRNAs were also detected in the gonads and pituitary gland, and sbGnRH expression was much higher than that of sGnRH, indicating the critical role of sbGnRH in regulating the BPG-axis. Moreover, the brain expression patterns of sbGnRH and sGnRH mRNAs showed an increased trend during gonadal development, peaking in mature stages. This indicated the direct regulation of gonadal development by the GnRH system. In addition, cGnRH - II mRNA expression showed no significant variations, suggesting that cGnRH-II is not critically involved in the control of reproduction. Further, the mRNA abundances of the three GnRH forms in the breeding season were significantly higher than those in immature and post-breeding stages in all analyzed brain areas. Therefore, we propose that sbGnRH is the most important hormone for the regulation of reproduction in turbot via the BPG-axis. These results will help in better understanding the reproductive endocrine mechanisms of turbots and lay the groundwork for additional studies aimed at comparing the reproductive physiology of wild individuals with those raised under artificial conditions.

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