团头鲂HPG轴相关基因对其性早熟的分子调控机理研究

鱼类的性早熟是在人工养殖过程中出现并影响其生长速度的主要因素之一。团头鲂作为我国重要的草食性经济鱼类,在长期人工养殖过程中,性早熟现象明显。HPG轴相关基因的SNP已经被证实与哺乳动物的性早熟密切相关,其中KiSS/GPR54被认为是动物性成熟的关键基因。本研究拟基于课题组454测序获得的团头鲂HPG轴相关基因的EST序列以及SNPs位点,在人工繁育群体中分析基因SNPs与其性早熟的相关性,筛选与其性早熟相关联的SNPs。同时分析HPG轴相关基因在个体性腺发育不同阶段的表达水平及基因之间的调控关系,构建KiSS和GPR54基因的超表达和RNA干扰表达载体,在活体水平上检测相关基因的转录和蛋白表达变化,初步解析团头鲂性早熟的分子调控机理。本项目的研究结果可为鱼类性早熟的分子机制提供一定的理论依据,筛选到的团头鲂性早熟相关联的SNP标记可促进其非性早熟品种的选育工作,具有一定的理论和育种意义。

Early puberty is one of the major problems in many farmed fish species due to negative effects on growth performance. As a main aquaculture species in the Chinese freshwater polyculture system with high economic value, the Megalobrama amblycephala is gradually exhibiting early sexual maturity under a long cultured period. Many studies had revealed the molecular regulation mechanism of HPG related genes on the early puberty in mammalian vertebrates and the SNPs of related genes in HPG axis have been demonstrated to be correlated with early puberty. This study was designed to screen the SNPs correlated with the early maturation of M. amblycephala and analyze the regulation mechanism of HPG related genes on its early maturation. Based on the ESTs and SNPs of the related genes in the HPG axis from the 454 pyrosequencing in our research team, the correlations of these SNPs with early maturation of M. amblycephala will be analyzed using its artificial reproduction population in this study to identify the SNPs significantly related to its early maturation through DNA MassArray? Technology. Also, allelic expression of the correlated SNPs in the genome DNA and cDNA will be compared to evaluate whether the allelic expression imbalance is existed during the gonadal development. In the meantime, the mRNA expression level of the HPG axis related genes will be compared in the different gonadal development stages to evaluate the regulatory relationships of these genes and its effect on the gonadal development. As the KiSS/GPR54 system plays a key role in sexual precocity in mammals, the over-expression and RNA interference vectors of these two genes will be constructed and its effect on the HPG related genes mRNA and protein expression in M. amblycephala will be analysed. The results from the present study could offer certain evidence for the molecular mechanism of fish early maturation. The identified SNPs related to the early maturation of M. amblycephala would facilitate its selective breeding. This study will be found to have the important meaning on theory and practical breeding.