title: Growth differences and dimorphic expression of growth hormone (GH) in female and male Cynoglossus semilaevis after male sexual maturation.
abstract: Half-smooth tongue sole, Cynoglossus semilaevis, is an ideal model to investigate the regulatory mechanisms of sexual growth dimorphism in fish species. The aim of the study was to investigate the effect of differential age of sexual maturity for females and males on growth and GH mRNA expression in C. semilaevis. The body weight differences between the sexes were not significant in C. semilaevis at age 5 months when females and males were all immature. Significant differences in body weight between the sexes were found after early sexual maturation of males at the age of 9 months. The body weight of 21-month-old females (621.4 ± 86.4g), still not immature, was even 3.28 times higher than that of the males (189.7 ± 14.4g). The cDNAs encoding GH in C. semilaevis was cloned. The GH gene is 2924bp long and consists of six exons and five introns. The results of qRT-PCR showed that GH mRNA levels of the immature females were not significantly different from that of immature males at age 5 months. However, GH mRNA levels of the immature females were significantly higher compared with those of the mature males at age 9 months (P<0.05). At age 11 months, GH mRNA levels of females were even 6.4-fold higher than that of males. In conclusion, for the first time we show that early sexual maturity of males is the main cause of sexual growth dimorphism in C. semilaevis and exert significant effect on GH mRNA expression.
authors.affiliation: Key Laboratory for Sustainable Utilization Development of Marine Fisheries, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China.
authors.forename: Xiang-Shan
authors.initials: XS
authors.lastname: Ji
authors.forename: Han-Wen
authors.initials: HW
authors.lastname: Liu
authors.forename: Song-Lin
authors.initials: SL
authors.lastname: Chen
authors.forename: Yun-Liang
authors.initials: YL
authors.lastname: Jiang
authors.forename: Yong-Sheng
authors.initials: YS
authors.lastname: Tian
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001835:Body Weight; D018076:DNA, Complementary / Q000235:genetics; D005260:Female; D005412:Flatfishes / Q000254:growth & development* / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D013006:Growth Hormone / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008969:Molecular Sequence Data; D009865:Oocytes / Q000502:physiology; D010802:Phylogeny; D012727:Sex Characteristics; D012741:Sexual Maturation / Q000502:physiology*; D013737:Testis / Q000254:growth & development / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D013006:Growth Hormone