Differential expression of cell cycle genes in rhesus monkey oocytes and embryos of different developmental...

Correct cell cycle regulation is especially challenging at the start of life. Ovulated oocytes must maintain meiotic arrest until fertilization, and then complete meiosis and initiate a series of modified cell divisions without growth. Moreover, myriad key developmental events, such as chromatin remodeling and transcriptional activation of the genome, are coordinated with each other via the cell cycle, particularly passage through the DNA synthesis phase (S Phase). We examined here the expression of more than 30 mRNAs related to cell cycle regulation in rhesus monkey oocytes and embryos and compared the expression of these mRNAs between oocytes and embryos of different developmental potentials. We find that the maternally inherited stores of cell cycle regulatory mRNAs are especially susceptible to disruption in cases of diminished oocyte and embryo quality in the rhesus monkey. In comparison to published mouse array data, we also observed striking species differences in the temporal expression patterns of many of these genes, suggesting that mechanisms of cell cycle control may differ and that the responses of oocytes and embryos to external insults may likewise differ.