The Effects Of Polyadenylation On Porcine Oocyte Maturation In Vitro

The in vitro maturation of oocytes includes both nuclear maturation and cytoplasmic maturation. Nuclear maturation is marked by the extrusion of the first polar body, whereas cytoplasmic maturation fulfils the role of accumulating stable messenger RNAs(m RNAs) and proteins. Prior to the activation of the zygotic genome, virtually no gene transcription occurs, and cytoplasmic polyadenylation prevents the degradation of m RNA. These polyadenylation processes play extremely important roles in oocyte maturation and genome activation.In this study, porcine follicular oocytes from large follicles(> 5 millimetre(mm))and small follicles(<3 mm) were examined at different developmental stages. The polyadenylation of maternal genes was inhibited by the addition of cordycepin and 3'-deoxyadenosine(3'-da) during the germinal vesicle(GV), GV breakdown(GVBD),metaphase I(MI), and metaphase II(MII) stages. In addition, the expression levels and poly-(A) tail lengths of the maternal genes Cyclin B1, cell division cycle 2(Cdc2), C-mos, bone morphogenic protein 15(BMP15), and growth differentiation factor 9(GDF9) were determined. Furthermore, expression levels of the mitogenactivated protein kinase(MAPK), which are closely related to maternal genes, were detected during these different maturation stages, and immunofluorescence were used to assess spindle formation and chromosome alignment in the examined oocytes. In large-follicle oocytes, the effects of inhibiting polyadenylation caused maturation rates to be significantly lower for the treated group than for the untreated group(p <0.01). Among small-follicle oocytes, the 3'-da group and the untreated group exhibited no significant differences in maturation rate(p > 0.05). Upon inhibition of the polyadenylation of C-mos, GDF9, and BMP15 in the small-follicle oocytes,compensatory increases in the expression levels of these genes were observed during the MII stage. Cyclin B1 played a significant role in promoting the maturation of large-follicle oocytes, whereas the expression levels of C-mos, GDF9, and BMP15 played a major role in the maturation of small-follicle oocytes. Polyadenylation contributes to the formation of dominant follicles and facilitates the selection of dominant follicles. However, the inhibition of adenylation somewhat affected the spindle formation-related propulsion and chromosome alignment in both large- andsmall-follicle oocytes.Polyadenylation plays keyroles in promotingfor large follicle oocyte maturation and cumulus expansion, while the small follicle of oocyte is relatively small and cumulus expansion does have a certain extent. Maternal genes polyadenylation have role in promoting the expression, thereby promoting gene by maternal oocyte maturation. Polyadenylation on oocyte spindle formation, chromosome alignment has a certain role in promoting and polyadenylation of small follicular oocyte spindle formation, chromosome alignment degree of influence than large oocyte large.This study is to be better understand the mechanism of oocyte maturation and makes basic research on embryo research to improve small follicular oocytes promotes the utilization of a certain significance.