基于转录组和代谢组学的团头鲂性早熟分子机制及其与生长发育之间的相互作用研究

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. Through the previous founding projects from National Natural Science Foundation, the applicants have investigated the molecular regulation mechanism of HPG related genes and let-7 miRNAs on the early puberty of M. amblycephala as well the relationship between growth and gonadal development. The present proposed project will further use the transcriptomics and metabonomics technologies to systematically analyze the variations of genes expression and contents of metabolites during the growth and gonadal development stages. The putative key genes and metabolites will be identified. Secondly, based on the whole genome sequencing data which have been finished by our research group, the present study will try to identify the functions of 3-5 keys genes related to early puberty of M. amblycephala. Thirdly, the putative key metabolites will be quantified in a large population to screen the biomarkers to identify the one-year-old early mature, one-year-old immature and two-year-old normal mature females. The results from this project would explain the genetic mechanism and regulation network for the mutual promotion and inhibition relationship of growth and gonadal development from the transcriptome, metabolome and key genes/ metabolites levels, which could offer the reference data for exploring the relationship between growth and gonadal development during individual’s development.

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重要因素之一，生长和性腺发育表现出相互促进-相互抑制的作用。申请人前期青年和面上基金分别探讨了团头鲂HPG轴相关基因和let-7 miRNAs对其生长和性腺发育的调控作用。此课题拟利用团头鲂性早熟和非性早熟家系，运用转录组和代谢组系统研究手段，揭示性早熟过程中生长和性腺发育相关组织基因表达和代谢物含量的变化，构建性早熟过程中生长和性腺发育互作的关键基因-代谢物调控网络，确定候选关键基因和代谢物；基于已获得的团头鲂全基因组，对3-5个关键基因的功能进行活体和细胞水平的基因抑制/敲除/过表达分析；对关键代谢物在性早熟和非性早熟家系不同阶段个体进行定量分析，筛选可鉴别1龄性早熟、1龄非性成熟和2龄正常性成熟个体的活体生物标志物。研究结果将从转录组、代谢组及关键基因/代谢物三个水平系统解析团头鲂性早熟的分子机制及其与生长发育之间互作的调控机制。

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重要因素之一，生长和性腺发育表现出相互促进-相互抑制的作用。本课题运用转录组和代谢组系统研究手段，揭示团头鲂性早熟过程中生长和性腺发育相关组织基因表达和代谢物含量的变化，构建性早熟过程中生长和性腺发育互作的关键基因-代谢物调控网络，确定候选关键基因和代谢物，主要完成了以下5个方面的研究任务。（1）开展团头鲂生长快慢群体全转录组比较分析，构建团头鲂生长相关ceRNA调控网络；开展团头鲂不同性成熟阶段肌肉和血清比较转录组分析，筛选到其肌肉和血液中调控性早熟的关键差异表达基因和信号通路。（2）通过团头鲂不同性成熟阶段肌肉和血液的代谢组比较分析，筛选到性成熟前后以及产卵前后雌性团头鲂肌肉和血浆组织中的显著差异代谢物。（3）将团头鲂生长和性成熟相关转录组和代谢组进行关联分析，构建生长和性腺发育直接的基因-代谢物网络，明确差异基因和代谢产物均显著定位到“甾体激素生物合成”、“脂肪酸代谢和“甘油磷脂代谢”等途径。（4）将构建的团头鲂生长相关的ceRNA网络在细胞水平上进行功能验证，鉴定到novel_circ_0001608和LNC_011955 可与 MamblycephalaGene14755（PIK3R1）竞争dre-miR-153b-5p，novel_circ_0002886和LNC_010094可与MamblycephalaGene10444（apip）竞争 dre-miR-124-6-5p，从而影响这些靶基因在肌肉生长和细胞凋亡过程中发挥作用，调控团头鲂生长；定量分析了雌激素受体基因在团头鲂不同年龄阶段的表达模式，结合模式生物斑马鱼中基因的敲除分析，初步解析雌激素受体基因对团头鲂雌性性成熟前后的生长具有明显的调控作用。（5）通过进一步开展团头鲂不同性成熟组血浆和肌肉组织的代谢组和转录组等组学联合分析，鉴定得到各个年龄段代表性代谢物，并初步筛选得到类固醇激素生物合成的关键中间体17α-羟基孕烯醇酮可作为团头鲂雌性个体性成熟的生物标志物。研究结果研究结果从转录组、代谢组及关键基因/代谢 物三个水平解析了团头鲂性早熟的分子机制，筛选的差异代谢物为生产上鉴定性早熟团头鲂亲本提供了技术途径。