广盐性鱼类在不同盐度下的HUFA合成能力的影响机制研究

Highly unsaturated fatty acids (HUFA) are fish’s essential fatty acids，and the ability of HUFA biosynthesis determines the degree of dependence of compound feed on fish oil rich in HUFA and further affect the development of aquaculture industry. Many cultured fish are euryhaline species, and their HUFA biosynthetic ability are affected by ambient salinities. However, the mechanisms are unknown. So, the present project plan to use the rabbitfish Siganus canaliculatus and red tilapia (Oreochromis mossambicus♀×O. niloticus♂) as experimental animals, whose HUFA biosynthetic ability display opposite change trend with ambient salinity, to investigate the affecting mechanisms of salinity on HUFA biosynthetic ability at the physiological and biochemical level as well as the molecular level, through studying the effects of salinity on endocrine system and glycometabolism as well as lipid metabolism, by cultural test and in vitro hepatocyte experiments, and with the techniques of nutriology, physiology, endocrinology, biochemistry and molecular biology as well as omics. The results will not only add new content for fully clarifying the regulatory mechanisms of HUFA biosynthesis in fish, but also provide scientific evidence and direction for precision nutrition, feed formulation and strategy formulation, and also are helpful for developing methods to increase fish’s HUFA biosynthetic ability and accelerate the healthy development of aquaculture industry, and thus are of important theoretic and practical significance. Besides, the conduction of this project is also helpful for keeping our research on the regulatory mechanisms of HUFA biosynthesis in the International front level.

高不饱和脂肪酸(HUFA)是鱼类的必需脂肪酸。鱼类HUFA合成能力决定其配合饲料对富含HUFA鱼油的依赖程度及其养殖业的发展。许多养殖鱼类具有广盐性特点，其HUFA合成能力受水体盐度影响，但影响机制还不清楚。本项目拟以盐度对其HUFA合成能力呈现相反影响结果的黄斑蓝子鱼和红罗非鱼为对象，通过养殖试验和肝细胞离体实验，借助营养学、生理学、内分泌学、生化与分子生物学、组学等手段，重点从盐度对内分泌系统及糖脂代谢的影响等方面，在生理生化及分子水平上深入研究盐度影响鱼体HUFA合成能力的机制。其成果将为全面揭示鱼类HUFA合成代谢调控机制增加新的内容，为广盐性鱼类的精准营养、饲料配方设计及养殖策略制订提供科学依据和指导，有助于研发提高鱼体HUFA合成能力的方法，促进养殖业健康可持续发展，具有重要的理论和现实意义。项目实施也有助于本课题组在鱼类HUFA合成调控机制方面的研究工作继续处于国际前沿水平。

高不饱和脂肪酸(HUFA；也称长链多不饱和脂肪酸，LC-PUFA)是鱼类正常生长及生理功能所需的必需脂肪酸(EFA)。鱼类HUFA合成能力决定其EFA需求特性及配合饲料中鱼油的添加水平及其养殖业的发展。许多养殖鱼类具有广盐性特点，其HUFA合成能力受水体盐度影响，但影响机制还不太清楚。本项目以黄斑蓝子鱼、罗非鱼、日本鳗鲡、卵形鲳鲹等广盐性鱼类为对象，通过养殖试验和肝细胞离体实验，借助多种现代生物技术研究手段，重点从盐度对内分泌系统及糖脂代谢的影响等方面，较系统深入地研究了盐度影响鱼体HUFA合成能力的机制。取得的主要成果有：①以罗非鱼为对象，弄清其在不同盐度下的HUFA合成能力及EFA需求特性，确定了盐度影响鱼体HUFA合成的重要激素（皮质醇、胰岛素）和基因（脂肪酸转运蛋白，Fatp）。②揭示了盐度通过影响红罗非鱼皮质醇的合成与分泌及Fatp2、Fatp6基因、HUFA合成相关基因的表达，参与鱼体HUFA合成调控的作用机制。③从转录水平、转录后水平及细胞信号通路水平，揭示了以黄斑蓝子鱼为代表的广盐性鱼类HUFA合成调控的新机制。④项目完成后，已发表论文24篇，其中SCI论文23篇；举办小型学术研讨会1次，参加国内学术交流20次，作学术报告14次，交流论文26篇；向世界基因库登记新基因序列12个；培养青年教师3名、博士后2名，毕业博士生5名、硕士生1名，超额完成约定的任务指标。通过项目实施，初步弄清了盐度影响鱼体HUFA合成能力的调控机制，为全面揭示鱼类HUFA合成代谢调控机制增加了新内容，具有重要理论意义；同时，为广盐性鱼类适宜养殖水体盐度的确定及不同盐度下配合饲料的脂肪源选择、EFA添加等提供依据，为探索通过饲料添加剂途径提高鱼体HUFA合成能力的新方法，有助于增加配合饲料中植物油替代鱼油的比例、减少鱼油使用量，具有重要的现实意义。