初级肌纤维形成时间对猪瘦肉量的影响及其调控机制

当前瘦肉率仍然是决定生猪价格的最重要指标，而肌纤维数目尤其是初级肌纤维数目是影响瘦肉量的重要因素。前期通过组织形态学研究发现，初级肌纤维在瘦肉量低的蓝塘猪出现的时间要早于瘦肉量高的长白猪。结合肌生成研究进展，我们提出：长白猪成肌细胞增殖时间长，分化形成初级肌纤维的时间相对较晚，以致有更多的成肌细胞产生，从而分化形成初级纤维多，瘦肉量也多，而蓝塘猪则相反。为证实这一假设，本项目拟增加研究瘦肉量更少的小型猪初级肌纤维形成时间，并通过肌管标志蛋白MyHC进行免疫组化进一步证实初级肌纤维形成的时间与瘦肉量的关系，在此基础上对瘦肉量不同猪种的成肌过程（胚胎14天至胚胎49天）采用基因表达谱测序、差异表达基因分析、调控通路构建与验证、关键先导因子DNA序列比较等方法进行研究，旨在阐明初级肌纤维形成时间差异的分子调控机制，为确立初级肌纤维形成时间作为提高生猪瘦肉量新靶标提供充分的科学理论依据。

At present, lean mass ratio was still the most important factor to determine commercial pig price. Myofibers particularly primary myofiber numbers was the most important factor effect lean mass. Through histomorphology, we found that Lantang pigs formed primary myofiber sooner than Landrace. combine with myogenesis research progress, we hypothesised that myoblast proliferation will last more time, and differentiate to primary myofibers later in Landrace than lantang pigs. Consequently, it will yield more myoblasts and more primary myofibers, which influence lean mass. To prove this idea, we focus on the time point of primary myofibre formation in miniature pigs. We plan to add research time point and through MyHC immunohistochemical staining to confirm the relationship between primary myofiber formation time and lean mass. Moreover, we are going to perfome transcriptome sequencing, differentially expressed genes analysis, signal pathway construstion and verification, key Pilot Factor DNA sequence comparison to investigate myogenesis in pigs (14 dpc to 49 dpc)different in lean mass. Our purpose is to determine the molecular regulation mechanism about the different formation time of the primary myofibers, and also to establish the formation time of primary myofibers as a new target in breeding to improve pork mass to provide adequate scientific and theoretical basis.