团头鲂为我国重要经济鱼类,在长期人工养殖中,性早熟现象明显。性早熟个体生长和性腺发育表现出相互促进-相互抑制关系，1龄阶段生长快、性腺发育快,而2龄阶段生长明显减慢,严重影响其产量。Let-7 miRNA在调控动物生长和性腺发育过程中发挥着重要作用。本研究基于课题组团头鲂小RNA组和转录组高通量测序数据,筛选let-7 miRNA家族中调控生长和性腺发育的关键miRNA,从关键miRNA、其前体及靶基因三个层次系统解析miRNA的作用与调控机理。应用人工合成miRNA及反义miRNA,在细胞水平实现其过表达及沉默, 深入分析关键miRNA的功能。基于课题组团头鲂选育家系,筛选与生长和性腺发育相关联的miRNA 靶标SNP位点。研究结果将解析let-7 miRNA对团头鲂生长和性腺发育的调控机制,深化理解鱼类生长和性腺发育之间相互促进-相互抑制关系,筛选到的关联SNP可应用于其遗传选育研究。

As a main aquaculture species in the Chinese freshwater polyculture system with high economic value, the blunt snout bream (Megalobrama amblycephala) is gradually exhibiting early sexual maturity under a long cultured period. The growth and gonadal development of early mature individuals exhibit mutual promotion and inhibition relationships, with fast growth and gonad development during the first year, however the growth rate during the second year decreasing significantly. Let-7 microRNA has been demonstrated to play the important functions in the growth and gonad development of mammals. Based on the small RNA and transcriptome data of M. amblycephala from high-throughput sequencing technology in our research team, this project will identify the key let-7 microRNA members which have the main regulation effects on the growth and gonadal development of M. amblycephala. Through the analysis of key let-7 microRNA, its pre-miRNA and targeted genes, the regulation mechnism of key let-7 microRNA will be analyzed. Using artificial synthetic miRNAs and its anti-miR miRNA to over-express and knockdown the key let-7 miRNA activity on cultured cells in vitro, its functions will be deeply analyzed. Morever, the SNP of the key let-7 miRNA and its targeted genes will be identified and the correlations of the SNP with growth and gonadal deveopment of M. amblycephala will be analyzed using selected families in our research team. The results obtained from this study will demonstrate the regulation mechanism of let-7 microRNA on the growth and gonadal development of M. amblycephala and make understanding on their mutual promotion and inhibition relationships. The identified SNP would facilitate M. amblycephala selective breeding program.