Transcriptional profile of major genes related to X-chromosome inactivation during bovine embryonic development
X-chromosome inactivation (XCI), an essential epigenetic event in female embryos, is involved in embryonic development and requires refined control mechanisms. Although studies in cattle have been contributing to the understanding of the dynamic mechanisms of XCI, no research has yet investigated XCI in elongated bovine embryos. We used qPCR to characterize the mRNA levels of five target genes (XIST, JPX, H2AFY, H2AFY2, and EZH2) related to XCI in bovine embryos at stages: 8-16-cells (72 embryos), morula (72 embryos), blastocyst (64 embryos), hatched blastocyst (64 embryos), D11 blastocyst (20 embryos), and D14 (biopsies of 4 biopsies of embryos). Our results showed the same mRNA levels of XIST, JPX, and H2AFY2 at the morula stage, which were higher than those of the other genes. However, JPX declined after the morula stage, whereas XIST and H2AFY2 maintained higher mRNA levels in BL and HB. The expression of XIST and H2AFY2 reached the lowest levels at D11 and D14. We suggest that the changes in mRNA levels of these genes in the initial stages of development are related to the onset of XCI in cattle. This study is relevant to improve our understanding of the dynamic mechanisms that act in XCI in cattle until the elongated embryo stage.