精氨酸对点带石斑鱼营养代谢和免疫力调控机理的研究

Dietary plant protein supplementation can cause intestinal mucosa pathological changes in some fish, including damages to the integrity of the intestinal structure, degradation in intestinal function and reducing the absorption of nutrients, which restrict the dietary plant protein supplementation level. However, recent evidence shows that some functional amino acids, such as arginine, and its metabolites significantly influence nutritional metabolism, immunity, resistance to pathogenic organisms in various fishes, as well as improving intestinal structure and function. In this project, series of feeding trials will be conducted to investigate the effects of dietary arginine on nutritional metabolism and immune responses in grouper (Epinephelus malabaricus), which is one of the most important commercial marine fish in China, fed diets supplemented with graded levels of soybean meal. Also, analyze the difference of intestinal structure between these experimental treatments. On the basis of experimental results, select sensitive index related to immune responses of grouper regulated by arginine, and then establish the relationship of arginine with nutritional metabolism, intestinal morphology and immune responses of grouper, as well as explore the reaction mechanism of metabolism and immune responses that may be affected by arginine based on molecular level. Experimental results may provide the theoretical basis for decreasing the supplementation of fish meal in diets of grouper and culture cost.

饲料中添加植物蛋白会导致部分鱼类肠黏膜发生病理变化，表现为肠道结构的完整性受损，肠道功能降低，对营养物质的吸收减少，从而制约了植物蛋白在饲料中的添加量。而最近的研究表明部分功能性氨基酸如精氨酸及其代谢产物能显著影响鱼类的营养代谢、免疫力及抗病力，并且有改善肠道结构和功能的作用。本项目拟以我国重要的海水经济鱼类点带石斑鱼为研究对象，通过摄食生长实验，研究点带石斑鱼饲料中豆粕替代鱼粉并添加不同水平的精氨酸后，对其代谢及免疫力的影响，同时分析鱼体肠道粘膜结构的变化。在此基础上，筛选精氨酸调控点带石斑鱼代谢及免疫力相关敏感指标，建立点带石斑鱼精氨酸与营养代谢、肠道结构和免疫力之间的关系，从分子水平上探明精氨酸对鱼体营养代谢和免疫力的作用机理。实验结果可为生产上进一步降低点带石斑鱼饲料中鱼粉使用量，减少养殖成本提供理论依据。

以我国经济海水鱼类点带石斑鱼为研究对象，通过前期腹腔注射预实验，探讨了精氨酸对点带石斑鱼相关免疫指标及重要细胞因子胰岛素样生长因子和白介素分泌量的影响，筛选了点带石斑鱼敏感的免疫指标。通过单因素豆粕替代鱼粉实验，寻找到点带石斑鱼饲料中适宜的豆粕替代水平，在此基础上研究精氨酸添加水平和豆粕替代水平的交互作用对石斑鱼生长代谢、免疫和肠道结构的影响，发现添加精氨酸后显著提高了石斑鱼饲料中豆粕替代鱼粉的比例，替代鱼粉蛋白的比例从20%增加到30%。补充精氨酸后显著提高了血清免疫球蛋白IgG、白细胞介素IL-2、血清NO水平，对肝脏IGF-1、IgM基因表达有上调的趋势，初步分析精氨酸在石斑鱼体内的代谢主要还是通过NO途径，精氨酸能调节体内NO含量，使之有利于机体免疫力的提升。课题组成员参加国际会议2次，发表（或待发表）论文5篇，1篇处于审稿中。其中SCI等三大检索收录3篇，申请专利1项，培养研究生3名，项目组成员有3人晋升副高级职称，1人晋升中级职称。