自古以来，我国养牛业一直以役用为主、肉用为辅。但牛肉所具有的高蛋白质、高氨基酸、低胆固醇等特点，使其在国民总膳食中的所占比重逐年上升；另外，为缓解“人畜争粮”矛盾，国家大力支持“草食畜牧业”发展，这对我国养牛业提出了从传统役用向专业肉用转型的战略要求。然而，在追求牛肉产量的同时，肉牛产业面临着改善牛肉品质、提高牛肉档次的迫切任务。. 肌内脂肪（IMF）是影响牛肉质量的关键因素，调控肉牛IMF沉积和脂质代谢已被证明是改善牛肉品质的有效途径；此外，产业中普遍存在片面追求脂肪沉积而过度育肥的现象，这导致肉牛脂肪组织发生氧化应激并降低了牛肉品质。因此，挖掘对肉牛脂肪发育、脂质代谢和抗氧化应激有重要调控作用的功能基因，已成为肉牛育种工作中亟待解决的关键问题。. 沉默信息调节因子2（Sirtuins）能够调控细胞的增殖分化、衰老凋亡、能量代谢、应激反应等重要生物学过程。本人前期研究发现，SIRT5基因编码蛋白定位于牛前体脂肪细胞的线粒体内，能够抑制细胞分化和脂质沉积，并促进线粒体生物合成；然而，关于SIRT5通过线粒体调控脂质代谢的作用机理尚不明确。. 本项目以线粒体在脂质代谢和氧化应激中的关键节点作用为研究核心，探索SIRT5在牛前体脂肪细胞分化过程中对线粒体机能和脂质代谢的影响；分析SIRT5通过线粒体调控牛前体脂肪细胞脂质代谢的作用特点及过程；揭示SIRT5在氧化应激条件下调控牛前体脂肪细胞抗氧化应激、凋亡和线粒体功能的分子机理。以期为调控肉牛IMF沉积与改善牛肉品质提供理论依据，并为肉牛分子育种工作提供研究基础。

Since ancient times, the cattle industry in China has been dominated by servitude and supplemented by meat use. But beef has the characteristics of high protein, high amino acid, and low cholesterol, which makes its proportion in the total national diet increase year by year. In addition, in order to alleviate the contradiction of "human and animal competition for food", the state strongly supports the development of "herbivorous animal husbandry". This puts forward a strategic requirement for China's cattle industry to transform from traditional servitude to professional meat use. However, while pursuing beef production, the beef cattle industry is faced with the urgent task of improving the quality and grade of beef. . Intramuscular fat (IMF) is a key factor affecting the quality of beef, and regulating IMF deposition and lipid metabolism in beef cattle has been proved to be an effective way to improve beef quality. In addition, excessive fattening due to one-sided pursuit of fat deposition is a widespread phenomenon in the industry, which causes oxidative stress in the adipose tissue of beef cattle and reduces beef quality. Therefore, the discovery of functional genes, which have important regulatory effects on adipose tissue development, lipid metabolism and anti-oxidative stress in beef cattle, has become a key issue that needs to be solved urgently in beef cattle breeding.. Silent information regulator 2 (Sirtuins) can regulate important biological processes such as cell proliferation and differentiation, senescence and apoptosis, energy metabolism, and stress response. The applicant's previous research found that the protein encoded by SIRT5 gene was located in the mitochondria of bovine preadipocytes, which inhibited cell differentiation and lipid deposition, while promoted mitochondrial biosynthesis. However, the action mechanism by which SIRT5 regulates lipid metabolism via mitochondria is still unclear. . This project focuses on the key node role of mitochondria in lipid metabolism and oxidative stress, explore the effects of SIRT5 on mitochondrial function and lipid metabolism during the differentiation of bovine preadipocytes, and analyze the function characteristics and processes of SIRT5 regulating lipid metabolism of bovine preadipocytes via mitochondria; and reveal the molecular mechanism of SIRT5 regulating the antioxidant, apoptosis, and mitochondrial function of bovine preadipocytes under oxidative stress. It is expected to provide a theoretical basis for the regulation of beef cattle IMF deposition and beef quality improvement, and provide a research basis for beef cattle molecular breeding.