RESUMEN
CONTEXT: With two northern white rhinos (NWR) remaining, the continued existence of this species relies on studying their relative, the southern white rhino (SWR). AIMS: (1) Characterise gene expression in granulosa cells (GC) from SWR cumulus oocyte complexes (COCs) prior to (Pre-) and after (Post-) in vitro maturation (IVM), comparing culture media and oocytes from donors treated with or without gonadotropin stimulation prior to ovum recovery; and (2) evaluate COC glucose consumption in spent media. METHODS: COCs were retrieved from four SWRs. Granulosa cells were collected before and after IVM in SDZ or IZW medium. Total RNA was evaluated by qPCR. KEY RESULTS: Oocyte maturation was greater in SDZ than IZW media. Expression of genes associated with follicle development increased in Pre-IVM GC. Six genes were differentially expressed in Post-IVM GC from stimulated compared to unstimulated donors. COCs from stimulated animals consumed more glucose. Fifty seven percent of oocytes in SDZ medium consumed all available glucose. CONCLUSIONS: Gene expression changed upon in vitro maturation and gonadotropin stimulation. Higher glucose availability might be needed during IVM. IMPLICATIONS: This is the first study examining GC gene expression and COC metabolic requirements in rhinoceros, which are critical aspects to optimise IVM of rhinoceros oocytes.
