高脂胁迫下细鳞鲑脂肪代谢应答及营养调控机制

High-fat diet has been widely used in carnivorous cold-water fish. Since the requirements and utilization for lipid are limited by physiological conditions, metabolism disorder during culture and quality deterioration after feeding high-fat for a long time will happen easily, which would affect the health and quality of fish seriously. In this project the changes of related enzymes and expression of functional genes for lipid metabolism of Manchurian Trout (Brachymystax lenok) were studied by nutrient culture experiment, transcription group, molecular cloning and real-time PCR. The high-fat model for carnivorous cold-water fish will be constructed, furthermore, the difference of gene expression for adipose tissue induced by high-fat and normal lipid level were selected and compared, thus to reveal the operating mechanism of lipid and normal fat feed and high-fat diet feeding induced differences in gene expression in adipose tissue of fish; It is to construct a high-fat diet model for carnivorous cold-water fish, to study the mechanism of fat metabolism and imbalance of fine-scaly fish, to clarify which metabolic pathways and molecular networks affect the fat metabolism of fish, and to reveal the response regularity of fat metabolism in trout. The relationship between exogenous lipase and choline as nutrient regulators and genome associated with lipid metabolism of Manchurian Trout will be explored.And the metabolic pathways and molecular networks to regulate lipid metabolism would be elucidated. In addition, the effects and regulation of lipid and its mechanism to high-fat diet will be revealed. The present study reveals the regulation and mechanism of fat metabolism in trout under high-fat stress, reduces ectopic fat deposits and improves the quality of fish meat through nutrient regulation of fat metabolism, and lays the foundation for lipid metabolism pathways of cold water fish and molecular mechanisms of nutrition regulation. The application of exogenous lipase and choline in fish feed provides new ideas.

高脂饲料在肉食性冷水鱼类中应用已普遍存在，由于对脂肪需求和利用能力受到生理条件的限制，长期摄食高脂饲料会引起鱼类养殖期易发生脂肪代谢障碍和养殖后肉质下降，严重影响其健康和品质。本项目以细鳞鲑为研究对象，采用营养学养殖实验、转录组和荧光定量PCR技术相结合，分析高脂胁迫下细鳞鲑脂肪代谢相关酶和功能基因表达的变化，进一步筛选和比较常脂饲料投喂和高脂诱导对鱼体脂肪组织基因表达的差异；构建肉食性冷水鱼类高脂模型，开展细鳞鲑脂肪代谢及失衡机制研究，阐明通过何种代谢通路和分子网络影响鱼类脂肪代谢，探索细鳞鲑机体脂肪代谢应答规律；研究以外源脂肪酶和胆碱为营养调控因子，与细鳞鲑脂肪代谢相关基因组的关系。本研究揭示在高脂胁迫下细鳞鲑脂肪代谢的调控作用与机理，通过营养调控脂肪代谢来降低鱼体脂肪异位沉积和改善鱼肉品质，为冷水鱼脂肪代谢通路及营养调控分子机制奠定基础和外源脂肪酶、胆碱在鱼类饲料中的应用提供新思路。

在肉食性冷水鱼养殖中应用高脂饲料非常普遍，产生脂肪代谢障碍和养殖后肉质下降的不良影响不容忽视。了解高脂胁迫造成肉食性冷水鱼脂肪沉积的规律及调控机理途径，以及通过何种途径来恢复养殖鱼类健康，并提高鱼肉品质是业内亟需解决的问题。本项目以我国北方特有的陆封型冷水鱼细鳞鲑为研究对象，采用营养学养殖实验、组织形态学、转录组和荧光定量PCR技术相结合，分析高脂胁迫下细鳞鲑脂肪代谢相关酶和功能基因表达的变化，开展细鳞鲑机体脂肪代谢应答规律的研究。并以外源脂肪酶和胆碱为营养调控因子，揭示此两种营养调控与细鳞鲑脂肪代谢的关系。通过转录组研究和高通量测序与数据分析，筛查细鳞鲑肝脏中与脂肪代谢有关联的基因，探究外源脂肪酶和胆碱调控细鳞鲑脂肪代谢有关信号通路。结果表明饲料脂肪和脂肪酶水平交互作用对细鳞鲑终末体重、增重率和特定生长率都存在显著影响(P﹤0.05)。筛查细鳞鲑肝脏中与脂肪代谢有关联的基因共8个，添加脂肪酶可以改善细鳞鲑的脂肪酸谱，对其组成和含量都有正向调节，而且有效改善高脂胁迫的负面影响，在饲料脂肪水平为225.1g/kg时补充5000U/kg外源脂肪酶，可提高细鳞鲑幼鱼的生长性能，减少内脏脂肪的沉积，尤其是幽门盲囊外围脂肪的沉积，改善细鳞鲑的血液生化指标、肝脏抗氧化能力，并同时改善了细鳞鲑肌肉脂肪酸组成和含量，提高EPA和DHA的比例。在高脂饲料中，已制作完成添加不同含量胆碱饲料，将对细鳞鲑进行养殖试验并解析外源胆碱对高脂胁迫细鳞鲑脂肪代谢酶相关功能基因调控机制，完成高脂胁迫下细鳞鲑脂肪代谢应答及营养调控机制任务。本研究揭示在高脂胁迫下细鳞鲑脂肪代谢的机制，通过外源营养调控脂肪代谢来降低高脂饲料的影响，为冷水鱼脂肪代谢通路及营养调控分子机制奠定基础，并为外源脂肪酶、胆碱在鱼类饲料中的应用提供参考。