繁殖期大菱鲆雄性生殖细胞增殖和成熟过程及其机制解析

The development and maturation of fish gonad is a complex cellular process with numerous signal molecules regulation. During the artificial reproduction period in flatfishes, the induction of male gonadal development has always been neglected, which leads to the retardation of male gonad, along with the consequence of low sperm production and motility. The low quality and quantity of sperm further reslult in the dissatisfied fertilized eggs and fingerling yield, which affects the breeding seriously. How does the level of secreted progestin vary during breeding season? How does this change affect the spermatids proliferation and the improvement of their structure and function? How does the surrounding micro-environment cooperatively complete the spermatozoa maturation with desired yield and quality? All these challenges remain yet to be resolved. In this project ,we will use the matured males of turbot during breeding season to resolve the following questions:1) the variation of progestin levels during testis maturation; 2)the chain reactions stimulated by the changes of progestin level, including rapid meiosis and proliferation of spermatocytes, the expression of progestin receptors on sperm membrane; sperm structures and functions;and the influnces of those closely related genes expression on the spermatids structure and functions and semen yield and quality;2) combined with the Sertoli cells, Leydig cells and also the changes of micro-enviroment, to elucidate the mechanisms of turbot germ cell proliferation and maturation during breeding season from histology, cellular and molecular developmental biological persectives. The results of this project will enrich the basical theory of marine fish reproduction, development, and optimize the artificial technique for mairine fish gonadal development and induction.

鱼类性腺发育和成熟是众多信号参与的分子网络调控的细胞学过程。鲆鲽类人工繁育生产中，雄性亲鱼产精量低、性成熟人工诱导技术不精确而导致的精子质、量低下等已成为制约鲆鲽类优质受精卵生产的关键因素之一。雄鱼繁殖期孕酮分泌水平如何变化?孕酮变化如何影响精子细胞的增殖和结构、功能的完善？周围微环境的变化如何调节精子成熟和精液质、量？等一系列问题需要深入探索。因此本项目将以繁殖期内的大菱鲆为对象，研究精巢成熟过程中孕酮的分泌水平变化；孕酮变化与精母细胞快速的减数分裂增殖，与精子细胞膜表面孕酮受体的表达之间的链锁关系；以及其他与之密切相关的基因的表达变化对精子结构和功能，精液质量和产量的影响，并结合期间Sertoli细胞、Leydig细胞及输精管微环境的变化，从组织学、细胞及分子发育生物学水平阐明大菱鲆繁殖期雄性生殖细胞增殖、成熟过程和机制，丰富海水鱼类繁殖、发育基础理论，优化海水鱼类人工性腺发育诱导技术

鱼类的生殖是维持种群及遗传信息延续的重要生命活动，而配子的产生是其中最重要的一环。鲆鲽鱼类人工繁育生产中，雄性亲鱼产精量低、性成熟人工诱导技术不精确而导致的精子质、量低下等已成为制约鲆鲽类优质受精卵生产的关键因素之一。有关鱼类繁殖期雄性生殖细胞的增殖和成熟的机制目前并不明确。本项目以人工养殖的大菱鲆为研究对象，通过解剖学、组织学和电镜观察，揭示了大菱鲆雄性生殖细胞在精子发生过程中的细胞学变化过程，并绘制模式图；通过超微结构观察结合体细胞标记基因（amh, sox9）的时空表达模式，揭示了大菱鲆Sertoli细胞的发育动态变化规律，建立了繁殖期大菱鲆Sertoli细胞形态、结构的动态变化基础信息；大菱鲆精巢属于小叶型；成熟方式为半囊型；精小囊在精原细胞时期，由2-3个Sertoli细胞组成；阐明孕激素及其受体在大菱鲆精子成熟过程中起了重要作用：孕酮具有促进精母细胞减数分裂及与膜受体结合提高精子的活力，通过调节pH、精浆流动性等对精子的成熟起作用。从组织学、细胞及分子发育生物学水平阐明了大菱鲆繁殖期雄性生殖细胞增殖、成熟过程和机制，对于丰富海水鱼类繁殖、发育基础理论，优化海水鱼类人工性腺发育诱导技术具有重要意义。