Plasma exosomes have been identified to be involved in embryo development and implantation. In this study, the plasma exosomes of seven pregnant cows on day 16 and seven non-pregnant cows were collected. Exosome miRNA profiles were revealed by RNA sequencing technology and the abundance of exosome miRNA between them were compared. Seven miRNAs were significantly differently expressed (p-value < 0.05, |log2(FoldChange)| > 1), with five miRNAs upregulated and two downregulated in the pregnant cow group. The most significant miRNA was bta-miR-136 (downregulated in pregnant cows, p-value < 0.005). A total of 5828 target genes were computationally predicted for the seven miRNAs. GO and KEGG enrichment analyses showed these targets were significantly involved in several biological processes and pathways associated with embryo implantation and endometrial development, such as cell adhesion, cell junction, focal adhesion, Ras signaling pathway and Rap1 signaling pathway. This study identifies seven differentially expressed plasma exosomes miRNAs on day 16 of pregnancy in cows, with bta-miR-136, bta-miR-199b, and bta-miR-382-3p emerging as candidate miRNAs for future studies on maternal–fetal communication and embryo implantation.

DNA polymerase β (DNA polymerase beta (POLB)) belongs to a member of the DNA polymerase X family, mainly involved in various biological metabolic processes, such as eukaryotic DNA replication, DNA damage repair, gene recombination, and cell cycle regulation. In this study, the muscle development-related gene POLB was screened by selection signature and RNA-seq analysis and then validated for the proliferation and apoptosis of bovine primary myocytes. It was also found that overexpression of the POLB gene had a pro-apoptosis effect, but interfering with the expression of the gene had no significant effect on cells. Then, the analysis of related apoptotic genes revealed that POLB overexpression affected CASP9 gene expression.