鳜鱼AAR信号通路感知驯食饲料赖氨酸与蛋氨酸营养平衡机理研究

Live bait fish is difficult to stably supply throughout the year and has the risk of carrying pathogens, the artificial feed acclimation is an effective way to solve the problem of mandarin fish farming. Although the fishmeal is effective for acclimating mandarin fish, its resources are scarce and its development is unsustainable. Accordingly, it needs to rely on the use of alternative protein sources, but the alternative protein is unsatisfactory for acclimating mandarin fish. Even if the anti-nutritional factors were eliminated in the alternative protein, the mandarin fish acclimation was still not effective. The feed intake and protein deposition were increased in the mandarin fish artificial feed acclimation after the balance of feed lysine and methionine by project applicant. The literature analyses show that the amino acid response (AAR) signaling pathway can sense the balance of amino acids, but the regulation of feeding mechanism by AAR signal pathway sensing the nutritional balance of lysine and methionine in mandarin fish is not clear. Based on the whole genome of mandarin fish and our previous studies, this project uses amino acid balance sensing as the penetration point, and studies the changes in the appetite and free amino acid contents of mandarin fish after balance of lysine and methionine at the levels of living body and cells, and analyzes the changes of AAR signaling pathway related protein expressions by the transcription and proteomics, and systematically studies the key gene expressions and receptor phosphorylation levels of this signaling pathway, and further clears the amino acid balance sensing signal transduction pathway. This project aims to reveal the nutrition sensing mechanism of the balance of lysine and methionine in acclimation feed of mandarin fish, and also provide a theoretical basis for the balance of feed amino acids to promote the artificial feed acclimation in mandarin fish.

活饵料鱼难以全年稳定供应且存在携带病原风险，驯食配合饲料是解决鳜鱼养殖难题的有效途径。鱼粉驯食鳜鱼效果虽好，但其资源紧缺且发展不可持续，需依赖替代蛋白源的使用，而替代蛋白驯食鳜鱼效果不理想。即使将替代蛋白抗营养因子消除后，鳜鱼驯食饲料效果依然不佳，申请人平衡饲料赖氨酸和蛋氨酸后显著提高了鳜鱼摄食和蛋白质沉积。文献分析显示氨基酸应答（AAR）信号通路可感知氨基酸平衡，但鳜鱼AAR信号通路感知赖氨酸与蛋氨酸营养平衡调控摄食饲料机理尚不明确。基于鳜鱼全基因组和前期研究基础，本项目以氨基酸平衡感知为切入点，从活体和细胞水平研究赖氨酸与蛋氨酸平衡变化时鳜鱼食欲及组织游离氨基酸含量变化，结合组学分析AAR信号通路相关蛋白表达变化，系统研究该通路关键基因表达和受体磷酸化水平变化，并进一步明确氨基酸平衡感知信号转导途径，旨在揭示鳜鱼感知赖氨酸与蛋氨酸营养平衡机理，为平衡饲料氨基酸促进鳜鱼驯食提供理论依据。

活饵料鱼难以全年稳定供应且存在携带病原风险，驯食配合饲料是解决鳜鱼养殖难题的有效途径。鱼粉驯食鳜鱼效果虽好，但其资源紧缺且发展不可持续，需依赖替代蛋白源的使用，而替代蛋白驯食鳜鱼效果不理想。即使将替代蛋白抗营养因子消除后，鳜鱼驯食饲料效果依然不佳，申请人平衡饲料赖氨酸和蛋氨酸后显著提高了鳜鱼摄食和蛋白质沉积。文献分析显示氨基酸应答（AAR）信号通路可感知氨基酸平衡，但鳜鱼AAR信号通路感知赖氨酸与蛋氨酸营养平衡调控摄食饲料机理尚不明确。通过国家基金项目的支持，在研究植物蛋白替代鱼粉效果评估的基础上，开展氨基酸缺乏对鳜鱼摄食和排泄的研究，同时分析了鳜鱼脱氨关键基因GDH和AMPD的结构与功能。按照基金实施计划，以鳜鱼为研究对象，开展了饲料赖氨酸平衡、蛋氨酸平衡度变化时（单种氨基酸浓度变化），鳜鱼对单个氨基酸平衡度变化的感知，研究了鳜鱼摄食和排泄的变化及调控机理。接着开展赖氨酸和蛋氨酸不同比例时，鳜鱼摄食和排泄的变化，进行转录组分析，结合常规成分、酶活性变化和基因表达等检测，分析鳜鱼氨基酸平衡感知机理。在此研究的基础上，进一步开展发酵豆粕替代鱼粉后，补充晶体或包膜赖氨酸与蛋氨酸，研究鳜鱼摄食和排泄变化，发现氨基酸平衡后鳜鱼对发酵豆粕摄食较好，但通过脱氨过程分析得出，鳜鱼饲料氨基酸平衡后依然存在氨排泄高的现象。因此，从氨排泄角度，开展了鳜鱼降排氨添加剂的筛选与使用，得到了一个显著降低排氨的添加剂组合，成分简单且添加方便，并应用于发酵豆粕在鳜鱼饲料中的使用，降氨效果非常显著。下一步工作将围绕筛选出的降氨氮添加剂在鳜鱼饲料中的应用，进一步精确其添加比例，并揭示其降氨调控机理，优化鳜鱼实用型配方及可控水体饲料高效养殖。