Transcriptome Analysis of the Endometrium from Chinese Erhualian sows that differ in Calcium Ion Concentration and Litter Size

Embryonic survival rate is an important factor for the fecundity of sows, and it is affected by endometrium secreting histotroph. A higher concentration of calcium ion has been observed in the uterus of the high prolific Erhualian sows (EH) compared with low prolific ones (EL), which suggests EH sows had a greater establishment and maintenance of pregnancy, and thus increase embryonic survival rate during peri-implantation period. In order to understand the mechanisms of endometrium secreting histotroph affecting embryonic survival rate during Erhualian peri-implantation period, the expression patterns of endometrial mRNA in the EH and EL on day 12 of gestation were analyzed using RNA sequencing technology. 164 differentially expressed genes (DEGs) were identified (Padj < 0.05, |log2(FC)| = 1),including 46 upregulated and 118 downregulated genes in the EH group compared with EL group. Among these DEGs, 17 DEGs have been previously reported as DEGs in other pig breeds for litter size. Gene Ontology (GO) enrichment indicated that a subset of DEGs were involved in the calcium ion binding and cell adhesion. Solute carrier family 8 member A3 (SLC8A3) and solute carrier family 24 member 4 (SLC24A4) were upregulated genes (Padj < 0.05) in EH group and they were considered as key candidate genes expressed in endometrium to affect embryonic survival rate during peri-implantation period. The present results will aid in understanding the variation of litter size in Erhualian breed during peri-implantation period. Overall design: Endomerium mRNA profiles at day 12 of gestation between high and low prolific Erhualian sows

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