Nkadimeng Marble1,2*, van Marle-Köster2, Lekola Kgomotso4, Mphaphathi Masindi Lotus1, Lehloenya Khoboso Christina4, Pilane Cyril Mpho1, Nedambale Tshimangadzo Lucky1,3

Abstract | The study aimed to evaluate the effect of high temperature on cattle oocytes matured in vitro at 39, 41, 42, 43˚C and to evaluate apoptosis through Caspase-activity and DNA fragmentation on produced embryos. Cumulus oocyte complexes (COC) were matured at 39, 41, 42 and 43˚C. Two best maturation temperatures were selected for maturation throughout embryo production. Post maturation, matured oocytes were exposed to standard embryonic conditions. Embryos were evaluated at 3 stages: ≥ 2-4 cell, ≥ 8cell and blastocyst to determine Caspase-3 activity and DNA fragmentation. Maturation of oocytes at 41 and 39˚C demonstrated no significant difference (p>0.05) however, higher maturation rate compared to 42 and 43˚C. Matured oocytes at 39 and 41˚C showed no difference (p>0.05) in embryo development. Blastocysts at 39˚C maturation had higher (p<0.05) nuclei cells compared to those at 41˚C. Caspase-3 activity was comparable at ≥ 2-4 cell and ≥ 8cell for both 39 and 41˚C maturation temperatures, however, 41˚C showed high DNA fragmentation compared to 39˚C maturation group. Blastocyst from oocytes matured at 41˚C had higher Caspase-3 activity and DNA fragmentation than those at 39˚C. Embryos derived from 41˚C maturation temperature resulted in evidence of apoptosis compared to 39˚C.

Keywords | Oocyte maturation, High temperature, Embryos, Cell apoptosis, Blastocyst