Characterization of gene expression in mouse embryos at the 1-cell stage.

In mice, transcription from the zygotic genome is initiated at the mid-1-cell stage after fertilization. Although a recent high-throughput sequencing (HTS) analysis revealed that this transcription occurs promiscuously throughout almost the entire genome in 1-cell stage embryos, a detailed investigation of this process has yet to be conducted using protein-coding genes. Thus, the present study utilized previous RNA sequencing (RNAseq) data to determine the characteristics and regulatory regions of genes transcribed at the 1-cell stage. While the expression patterns of protein-coding genes of mouse embryos were very different at the 1-cell stage than at other stages and in various tissues, an analysis for the upstream and downstream regions of actively expressed genes did not reveal any elements that were specific to 1-cell stage embryos. Therefore, the unique gene expression pattern observed at the 1-cell stage in mouse embryos appears to be governed by mechanisms independent of a specific promoter element.