P-65: Maternal Effect Genes in Mammalian Reproduction

Background: Regulation of gene expression in mammalian embryos is not completely known. Pre-implantation embryos need maternal RNA and proteins synthesized during oogenesis, to regulate development before mater-embryo transition, as the grown oocyte and the 1-cell zygote are transcriptionally silent. There are some oocyte-specific genes called maternal effect genes which may account for this early cleavage regulation. Mater-embryo transition is done through gradual degradation and reduction of maternal RNA and proteins, and the occurrence of zygote genome activation. Identification of maternal factors like Mater, Npm2, Hsf1, Floped, Stella, Brg1, Zar1, Dnmt1 and Filia in mice, showed the importance of these genes in mammals. Materials and Methods: In this review, we will focus on some maternal effect genes causing reproductive dysfunction in different mammalian species. Results: These factors are preferentially expressed in growing oocyte, and their protein products remain until the late pre-implantation developmental stages. They have a highly impressive effect on developing embryos, as the embryos are blocked or growth-delayed in null type. So, maternal effect genes will alter reproduction rate in abnormal inheritance. Loss of maternal effect genes does not make change in female normal ovulation and fertilization, but causes infertility or subfertility due to failure in pre-implantation development. Conclusion: Hence, understanding the biology of such maternal factors and their genomic variations will help to find about the basis of some reproductive abnormalities and troubleshooting.