Identification and Preliminary Analysis of Granulosa Cell Biomarkers to Predict Oocyte In Vitro Maturation Outcome in the Southern White Rhinoceros (Ceratotherium simum simum).

Simple Summary: Granulosa cells play an essential role in oocyte meiotic competence acquisition by supplying nutrients and metabolites to oocytes and secreting paracrine signals that regulate oocyte maturation. Identifying biomarkers in granulosa cells to measure an oocyte's ability to mature in vitro noninvasively predicts success or failure prior to maturation. This technique also offers the opportunity to develop treatment strategies to overcome potential maturation failures. This study aimed to evaluate potential biomarkers associated with follicle development, meiotic competence, cell death and atresia, and embryonic genome activation in granulosa cells from oocytes that did or did not mature after in vitro fertilization in the southern white rhinoceros. This study determined eight potential biomarkers associated with the success or failure of an oocyte to mature. Two genes were correlated with follicle development, three genes with meiotic competence, and three genes with cell death and atresia. This is the first study in which in vivo granulosa cells were used as a diagnostic predictor of oocyte maturation competence in the southern white rhinoceros. It represents a critical evaluation needed to improve assisted reproductive technologies in this species. In recent years, biomarkers in granulosa cells (GC) have been determined and associated in several species with oocyte maturation, in vitro fertilization success, and embryo development outcomes. The identification of biomarkers of oocyte competence can aid in improving assisted reproductive technologies (ARTs) in the southern white rhino (SWR). This study aimed to identify biomarkers present in SWR GC associated with oocytes that either did or did not mature in vitro. We evaluated follicle development (FD), meiotic competence (MC), cell death and atresia (CDA), and embryonic genome activation (EGA). Our objective was to design biomarkers to predict oocyte in vitro maturation results in the SWR. RNA was isolated from GC obtained during ovum pick up (OPU) for qPCR analysis. Overall, 22 genes were assessed, and nine were differentially expressed between GC from oocytes that did or did not mature in vitro (FD-GDF9 and mTOR; MC-GGPS1, JMY, and NPR2; CDA-COL4A1, MACIR, and TMPO; EGA-NFYA). From these data, we determined that GC can be used as a predictor for oocyte in vitro maturation outcome in the SWR. Our results provide crucial information needed to improve in vitro maturation and ARTs in this species. [ABSTRACT FROM AUTHOR]