Principles of the Earliest Lineage Specification and X Chromosome Dosage Compensation in Bovine Early Embryos
Lineage specification and X chromosome dosage compensation are two crucial biological processes that occur during preimplantation embryonic development. While these processes have been studied extensively in mice and humans, they are less understood in other species. This study aims to provide fundamental insights into bovine preimplantation development using single-cell RNA-sequencing. The study analyzes the transcriptomes of 286 individual cells and reveals that bovine trophectoderm/inner cell mass transcriptomes diverge at the early blastocyst stage, after cavitation but before blastocyst expansion. The study also identifies transcriptomic markers and provides the timing of lineage specification events in the bovine embryo. Moreover, the study confirms the occurrence of X chromosome dosage compensation from morula to middle blastocyst and reveals that this compensation results from downregulation of X-linked genes in female embryonic cells. The transcriptional atlas generated by this study is expected to be widely useful in improving our understanding of mammalian early embryo development. Overall design: poly RNA profiles of  bovine embryos