线粒体能量代谢解析猪剩余采食量的分子机制

Residual feed intake (RFI) is defined as the difference between the actual feed intakes and the expected intakes required by the maintenance and growth of an animal during a special period. It is an important indicator to measure the feed efficiency. The main function of mitochondrion is to produce ATP through oxidative phosphorylation (OXPHOS) and provide energy for the body. Numerous studies have found some different indicators of mitochondrion function between animals with different RFI. Besides, the screened differential expressed genes has also been involved in mitochondrial energy metabolism. However, the systematic molecular mechanism of the RFI is still unknown. Based on our and others' previous research results, this project creatively put forward the scientific hypothesis that the RFI is regulated with mitochondrion energy metabolism in terms of genetics. So the objective is to reveal the molecular mechanism of pig RFI from the perspective of mitochondrion energy metabolism. High and low RFI pigs are used in the trial. To systematically analyze the relationship between RFI and the mitochondrion energy metabolism, the following three parts, including the energy metabolism related genes coding by nucleus, mitochondrion functional indicators, and mtDNA haplotype, are involved to build a complete regulatory network among them. The strong correlated genes or indicators of mitochondrion are screened out as markers. Therefore, the molecular mechanisms of pig RFI can be systematically studied focusing on mitochondrion energy metabolism.

剩余采食量(RFI)是在特定的测量期间真实采食量与通过维持和生长需要的预期采食量的差值，它是衡量饲料利用效率的重要指标；线粒体的主要功能是通过氧化磷酸化(OXPHOS)产生ATP，为机体提供能量。诸多试验研究证实，动物不同RFI之间线粒体的某些功能指标不同，或者筛选的差异表达基因参与了线粒体能量代谢，但是至今没有系统地揭示RFI的分子机制。结合本人和他人前期的研究成果，本项目创新性地提出RFI在遗传方面与线粒体能量代谢存在调控关系这一科学假设，拟从线粒体能量代谢角度解析猪RFI的分子机制。试验将以高和低RFI的猪为研究对象，从细胞核编码的能量代谢相关基因、线粒体的功能指标和mtDNA单倍型三个方面，系统地分析RFI与线粒体能量代谢之间的关系，构建它们之间完整的调控网络，筛选出与RFI强相关的基因或者线粒体指标作为标记，围绕线粒体能量代谢这一主线系统地研究猪RFI的分子机制。

剩余采食量（RFI）是在特定的测量期间真实采食量与通过维持和生长需要的预期采食量的差值，它是衡量饲料利用效率的重要指标；线粒体的主要功能是通过氧化磷酸化（OXPHOS）产生ATP，为机体提供能量。为了揭示猪剩余采食量的分子机制，本项目从线粒体能量代谢角度，围绕OXPHOS产生ATP这一主线，从细胞核编码的能量代谢相关基因、线粒体自身的结构和功能、线粒体DNA (mtDNA)单倍型三方面，逐层剖析并鉴定出影响线粒体能量代谢的关键因素。.高RFI（HRFI）组的剩余采食量比低RFI（LRFI）组高150 g/d（P<0.01）；HRFI组比LRFI组平均日增重高5.83%（P>0.05）；HRFI组比LRFI组的平均日采食量、料重比、背膘厚度分别高16.97 %、10.92 %、32.58 %，差异均显著（P<0.05）。以大白猪mtDNA全序（NC_000845）为参考序列，H1和H2的mtDNA全序SNPs位点分别有8个和7个，L1和L2分别有6个和7个SNPs位点，并且发现了几个SNP位点与报道的人类线粒体遗传病一致。H1和H2比L1和L2肝脏和背最长肌中的LDH活性要低；H1和H2心脏、背最长肌中Na＋K＋-ATP酶活性均极显著高于L1、L2（P<0.01）；H1和H2心脏、肝脏中ATP含量极显著高于L1和L2（P<0.01）；H1心脏中SDH的活性极显著高于L1和L2 (P<0.01)。H1和H2心脏、肝脏和背最长肌组织中COX1、Cyt b、ATP8、TFAM、AMPK1、IGF-1基因的相对表达量均显著或极显著高于L1和L2 (P<0.05或P<0.01)。.RFI在动物育种中有重要意义，猪肉是中国人民不可缺少的肉类，培育低RFI的猪群可以节约饲料，减少粪污的产量从而减轻对环境的污染。本项目研究证实，线粒体能量代谢与RFI有密切的关系，可以作为育种的目标。