光周期调控黑线仓鼠季节性繁殖的遗传机制研究

Seasonal breeding impacts the dynamics of population quantity, its genetic mechanism is a fundamental question of population ecology. Seasonal breeding is closely related with photoperiod. Recent studies has shown that kisspeptin encoded by Kiss1 gene was involved in the control of reproduction in animals mediated by photoperiod. But the relationship between the expression of kiss1 genes and photoperiod is not clear, the molecular regulation mechanism of seasonal breeding are also largely unknown. Previous work in our laboratory has shown that striped hamster (Cricetulus barabensis) is a typically seasonal breeder, which displayed seasonal changes in the expression of some genes related with reproduction. This project will choose striped hamster as the target animal, use the methods of molecular ecology, explore firstly the roles of central (brain) 'photoperiod-MEL-Kiss1' pathway and peripheral (gonad) 'MEL-gonadal Kiss1 gene-gonadal hormone' pathway in seasonal reproduction, including transcriptome analyses in related tissues, developmental and seasonal expression of candidate genes and the effects of photoperiod, exogenous MEL and kisspeptin treatment on reproduction and the expression of related genes (e.g. Kiss1). This study will reveal the gene regulation of photoperiod mediated seasonal reproduction in striped hamster, it also provide solid scientific evidence to understand genetic mechanisms of fluctuation and outbreak of rodents population and formulate measures of managing rodents pest.

季节性繁殖影响鼠类种群数量波动的遗传调控机制是种群生态学的研究热点之一。季节性繁殖与光周期密切相关。近来的研究表明Kiss1基因的产物是繁殖的控制者，参与了光周期对生殖的控制，但Kiss1基因与光周期调控季节性繁殖的遗传机制尚不清楚。我们前期的研究显示，黑线仓鼠是典型的季节性繁殖动物，部分繁殖相关基因的表达呈现出显著的季节性差异。本项目以黑线仓鼠为研究对象，采用分子生态学方法，首次探讨中枢（脑）"光周期-MEL-Kiss1通路"以及外周（性腺）"MEL-性腺Kiss1基因-性激素通路"对季节性繁殖的调控作用。研究内容包括相关组织转录组分析、Kiss1基因的季节性表达、光周期处理、外源MEL及Kisspeptin对繁殖及Kiss1基因表达的影响等。研究结果将揭示光周期在分子水平上是如何调控季节性繁殖的，为深入认识鼠类种群数量波动与暴发的遗传机制，以及鼠害综合控制措施的制定提供坚实的科学依据

动物种群数量波动机制是生态学领域的重要研究课题，季节性繁殖活动影响动物种群数量波动。鼠类作为生态系统的功能群，数量多，分布广，研究鼠类种群季节性繁殖的遗传调控机制是掌握动物种群数量波动机制的有效途径。黑线仓鼠是典型的季节性繁殖动物，适应性强，繁殖力高，具有春、秋两个繁殖高峰期，是研究动物季节性繁殖机制的理想模型。季节性繁殖活动又与光周期密切相关。本项目以不同光周期条件处理黑线仓鼠，研究了不同光周期条件下，在黑线仓鼠的“下丘脑－垂体－性腺轴”差异表达的基因，克隆分析了所筛选基因的结构，并对所筛选基因在不同组织、不同发育阶段、不同光周期条件下、及不同季节的差异表达量与黑线仓鼠下丘脑GnRH的表达量及血液性激素的浓度进行了关联性分析。研究结果表明，Kiss-1是光周期调控黑线仓鼠季节性繁殖活动的关键因子，RF 酰胺相关肽（RFRPs）对雌性黑线仓鼠的繁殖活动具有负调控效应，Dio2对光周期调控黑线仓鼠季节性繁殖活动中有正向调控效应，GDF9和BMP15是黑线仓鼠卵泡发育的主要调控因子，Tac3是调控黑线仓鼠性成熟的主要因子。因此，Kiss-1、RFRPs、Dio2、Tac3等基因是光周期在中枢（脑）"光周期-MEL-Kiss1 通路"以及外周（性腺）"MEL-性腺 Kiss1 基因-性激素通路"调控黑线仓鼠季节性繁殖活动的主要因子，其调控效应具有组织、发育阶段和性别特异性。本研究结果揭示了光周期通过“下丘脑－垂体－性腺轴”调控黑线仓鼠季节性繁殖活动的主效因子，及其调控效应，为深入认识动物种群数量波动与暴发的遗传机制，以及鼠害综合控制措施的制定提供科学依据。