猪胚胎附植失败导致胚胎死亡，从而影响母猪产仔数。猪胚胎在子宫腔系膜侧的定位是成功附植的前提，申请人在前期研究中利用数字切片扫描系统，发现猪附植期胚胎存在两种定位类型：系膜侧定位和系膜对侧定位，分别导致附植成功和失败两种结果，但猪胚胎附植定位的机制尚不清楚。本项目拟制备猪胚胎附植期的子宫组织切片，用激光捕获显微切割系统分离附植点胚胎和子宫内膜。创造性地将胚胎附植定位类型作为离散型质量性状，利用SNP芯片开展“胚胎-母体”基因互作全基因组关联分析，剖分胚胎、母体及胚胎与母体互作效应，结合目标区域捕获测序，筛选显著关联的基因组区域。检测两种定位类型的胚胎及子宫内膜转录组，并整合全基因组关联分析数据，获得重要候选基因。综合应用生物信息学、分子细胞生物学、群体关联分析等手段，鉴定影响猪胚胎附植定位的重要基因及其关键突变位点，解析两种胚胎附植定位类型差异的机制，为阐明猪产仔数的分子机制提供依据。

Failure in embryo implantation is the cause of embryo loss and has impact on litter size in pigs.The mesometrial allocation of the porcine implanting embryo along the uterine vertical axis is critical for subsequent establishment of implantaion. Previously, by using digital slide scanning system, we found that the implanting embryos have two types of orientation within the uterine cavity: positioning at mesometrial or antimesometrial region along the vertical axis, which result in successful or abnormal implantation, respectively. The mechanisms of orientation of implanting embryo in pigs remain unclear. In this project, we plan to prepare the cross sections of porcine uteri derived from the implantation stage and collect the embryos and endometrium tissue using laser capture microdissection system. The orientation type of implanting embryo is considered as a discrete quality trait and the genome-wide association “embryo-maternal” interaction analysis using SNP chip will be performed to dissect effects of the embryo, maternal and embryo-maternal interaction, respectively. Target-region capture sequencing will be applied for detecting the significant genome regions. The transcriptomes of embryos and endometrium from the two types of embryo orientation will be investigated to identify the candidate genes. Then the characterization of key genes and mutation site involved in orientation of implanting embryo will be carried out using approaches from different levels including bioinformatics cytology, molecule and population. The results are of importance for elucidation of the mechanisms that determine embryo orientation during the initial time of implantation and will be useful for identification of genes responsible for litter size in pigs.