Waldron, Connor; Moley, Laura; Isom, S. Clay (Utah State University)
Faculty Advisor: Isom, S. Clay (College of Agriculture and Applied Sciences; Animal, Dairy, and Veterinary Sciences Department)
In vitro maturation (IVM) is a process that immature oocytes undergo before in vitro fertilization is performed. During IVM, immature oocytes are extracted through aspiration from follicles and receive the necessary hormones to resume meiosis in culture. Success rate of IVM is significantly lower compared to in vivo maturation of oocytes. Oocytes selected for IVM are extracted from small ovarian follicles (1-3mm), which are 4-6 weeks away from complete maturation and subsequent ovulation. During that period, the DNA of the oocyte is undergoing the process of DNA methylation, the addition of a methyl group to cytosines within a CpG context. DNA methylation is an epigenetic change that causes modification to gene expression where methylated gene promoters turn off gene expression. Proper oocyte gene expression is very important in the development of a healthy embryo. Incomplete methylation of aspirated oocytes may be another factor contributing to the low success rates of IVM. We hypothesize that there is a difference in the amount of methylation between oocytes from small ovarian follicles that are further from natural ovulation and oocytes from large ovarian follicles which are developmentally closer to ovulation, with higher levels of methylation in oocytes from large ovarian follicles. To test our hypothesis, large porcine ovarian follicles (7mm and larger) and small porcine ovarian follicles (1-3mm) will be aspirated for ovaries. The oocytes will be stained the two stains, one to visualize the nucleus of the oocyte indicating the presence of DNA and the other to visualize DNA methylation. Fluorescent images will be taken of the oocytes, and the small and large follicle oocyte groups will be compared for genome wide methylation levels.