Hydrogen peroxide concentration and DNA fragmentation of buffalo oocytes matured in sericin-supplemented maturation medium
This study was conducted to investigate the effects of sericin on meiotic maturation, hydrogen peroxide (H2O2) concentration and deoxyribonucleic acid (DNA) fragmentation in buffalo oocytes. Oocytes were matured in vitro in tissue culture medium (TCM199) with in vitro maturation (IVM) groups under several conditions, namely without bovine serum albumin (BSA), (+BSA), and 0.025%, 0.05%, 0.1% and 0.25% (w/v) sericin. The results showed that supplementation of the maturation medium with 0.05% sericin significantly increased the rate of oocytes that reach metaphase II compared with other groups, except for the 0.025% sericintreated group. Intracellular H2O2 concentrations in oocytes of all groups were measured using 2',7'dichlorodihydrofluorescein diacetate (DCHFDA). The concentration of H2O2 in matured oocytes treated with 0.05% sericin was lower than in other groups. DNA fragmentation and the nuclear status of oocytes were examined using the terminal deoxyribonucleotidyl transferase-mediated dUTP digoxigenin nick endlabelling (TUNEL) method. The total proportion of TUNELpositive oocytes at the MII stage was lower in the 0.05% sericin group. The results indicate that addition of 0.05% sericin to the maturation medium may improve nuclear maturation and may inhibit DNA fragmentation in oocytes by decreasing H2O2 concentrations.
Keywords: antioxidant, apoptosis, in vitro maturation, reactive oxygen species