黄颡鱼氨氮解毒机制研究及其外源营养素调控

In the intensive aquaculture system, the occurrence of excess ammonia in aquatic environment appears to be the new norm, while non-ionic ammonia on all aquatic animals are toxic. After long-term evolution, the fish has yet evolved to adapt ammonia with a variety of detoxification pathways. As an effective regulation means, to achieve a precise regulation of these pathways with nutrients in fish feed largely depends on a thorough understanding of the ammonia detoxification mechanism of each cultured fish species. In this project, we will select the yellow catfish as our research object due to its strong stress resistance to the ammonia. With the combination of traditional physiological and biochemistrical, and modern molecular and omics techniques, we will focus on the regulation of key enzyme activities in ammonia metabolism, the metabolites perception of blood ammonia overload, nutritional supply and demand and turnover balance, and other systematic research, to gain an in-depth knowledge of ammonia detoxification mechanism and precise nutrient control strategy. The research results of this project will complement and improve the basic theories of fish physiology and nutrition, and provide theoretical support for the healthy and sustainable development of aquaculture.

水产高密度养殖系统中氨氮超标趋于常态化，非离子氨对所有水生动物均具有致毒性。在漫长的进化岁月里，鱼类逐渐分化出多种应答氨氮的解毒策略。作为一种有效的调节手段，要实现营养素的精准调控，取决于对养殖对象本身氨氮解毒机制的全面了解。本项目选取抗逆性较强的黄颡鱼为研究对象，采用传统生理生化、分子生物学与组学相结合的研究手段，围绕氨代谢关键酶活力控制、血氨过载的代谢物感知、营养素供需和周转平衡等进行系统研究，深入剖析黄颡鱼氨氮解毒机制和营养素精准调控策略。本项目研究结果将补充和完善鱼类生理学和营养学基础理论，为水产养殖业健康可持续发展提供理论支持。

在漫长的进化岁月里，鱼类逐渐分化出多种应答氨氮的解毒策略。作为一种有效的调节手段，要实现营养素的精准调控，取决于对养殖对象本身氨氮解毒机制的全面了解。本项目选取抗逆性较强的黄颡鱼为研究对象，通过比较转录组技术，筛选出适合黄颡鱼氨氮解毒的评价指标；通过RACE技术，获得关键基因CPS I和GS的全长cDNA序列；运用CRISPR/Cas9技术敲除和过表达CPS I基因，发现黄颡鱼氨氮解毒并不完全依赖于尿素循环；采用代谢组学技术结合13C稳定同位素标记技术，证实尿素循环和谷氨酰胺合成在黄颡鱼氨氮解毒过程中发挥重要作用；通过养殖实验，评价了外源营养素（蛋白质、纤维素、硒、丙谷二肽、牛磺酸及L-蛋氨酸亚砜亚胺）及饥饿再投喂对黄颡鱼氨氮解毒的影响。本项目研究结果将补充和完善鱼类生理学和营养学基础理论，为水产养殖业健康可持续发展提供理论支持。