猪胚胎死亡是影响产仔数的重要因素。胚胎的死亡高峰在其附植期，此时游离于子宫腔中的胚胎其发育和附植直接受子宫液中分泌蛋白的调控, 因此子宫液中的分泌蛋白在胚胎附植中具有重要作用。本研究以在胚胎死亡和产仔数上有差异的梅山和大白猪为研究对象，在妊娠12天（附植初期）、15天（附植中期）和18天（胚胎完成定位结束游离状态的时期），采用差异分泌蛋白组学策略，利用基于液相色谱串联质谱的非标记定量技术，获得差异分泌蛋白谱，通过Western杂交、原位杂交和免疫组化等方法验证差异分泌蛋白的表达模式。联合申请人前期获得的子宫内膜基因及miRNA表达谱数据，分析分泌蛋白的功能和介导的信号通路，在细胞水平进行验证，借助猪子宫内渗透泵灌注封闭抗体法，通过测量胎盘和胚胎发育等指标，研究重要分泌蛋白对猪胚胎发育和附植的作用。研究结果可为发现影响猪胚胎附植的重要调控因子奠定基础，为猪产仔数的遗传改良提供新的基因素材。

Early embryonic loss that occurs during implantation is considered the major limitation for increasing litter size in swine. The development and implantation of the free-floating conceptuses is mediated by the uterine secretory proteins. The central hypothesis is that we can discover and characterize proteins and their genetic pathways controlling the economically important trait of embryo survival through secretome analysis of specific, relevant stages of the conceptus and endometrium during early gestation in animals that differ for this trait. Previous studies have shown the difference in embryonic loss and litter size between Meishan and Large White breeds during implantation. Thus, we will characterize the changes in the uterine protein profiles between Meishan and Large White breeds gilts on days 12 , 15 and 18 of gestation through Label-free LC MS/MS and Western blotting, in situ hybridization and immunocychemistry techniques. By integrating data of gene and miRNA profile of endometrium obtaind from our previous studies using stepwise regression and structural equation modelling, we will analyze the function and the signal pathways involved in silico and in vitro.In addition, we will use a newly developed successful technique for immobilizing osmotic pumps in the porcine reproductive tract to deliver substances into the luminal cavity of the uterus in order to investigate the function and regulation of the important secretory proteins in embryo implantation. This proposal addresses the lack of fundamental molecular knowledge in pig reproductive biology through a multidisciplinary approach involving molecular genetics, reproductive biology, statistics, and bioinformatics. Knowledge gained through this approach will be integrated with existing genetics to accelerate improvement in reproduction traits that have a substantial economical impact for pork production.