SRA

While the equine oviduct clearly affects early embryo development and while the selective transport of equine embryos through the oviduct indicates a reciprocal interaction, the influence of the embryo on gene expression in the oviduct remains to be determined in the horse. The aim of this study was to examine this by means of RNA sequencing. Four days after ovulation, the oviduct epithelial cells ipsilateral and contralateral to the ovulation side from five cyclic and five pregnant mares were collected. mRNA was extracted and samples were sequenced using the Illumina Hiseq-2000 sequencer. Data analysis was performed with the CLC Genomics software and differentially expressed genes (DEGs) were determined (p-value = 0.05 and absolute fold change = 2). ClueGO was used for functional interpretation. A total of 26,991 genes was identified and 253 genes were found to be upregulated and 108 to be downregulated in the pregnant ipsilateral oviduct, when compared to the cyclic ipsilateral oviduct. Comparison of the ipsilateral and the contralateral oviduct indicated 164 DEGs in pregnant mares and 77 DEGs in cyclic mares. Functional enrichment analysis only detected differences in the comparison of pregnant and cyclic ipsilateral oviducts and showed that the equine embryo affects the expression of immune response related genes in the oviduct, with marked upregulation of interferon associated genes. This research represents the foundation for further assessment of the role of specific genes in the early embryo-maternal dialogue of the horse. Overall design: mRNA profiles of epithelial cells of equine oviducts ipsilateral and contralateral to the ovulation side of pregnant and cyclic mares four days after ovulation were examined, resulting in four different conditions (pregnant ipsilateral, pregnant contralateral, cyclic ipsilateral and cyclic contralateral, consisting of five biological replicates each.