Abstract：Seven-band grouper (Epinephelus septemfasciatus) is a seawater fish with high economic values that grow fast and tolerate strong with low temperature. Population quantity is less in the natural environment, and the germplasm resources for long-term preservation are imminent. Therefore, based on the cryopreservation of seven-band grouper embryos, the effects of cryopreservation (-196 ℃) on the enzyme activity (superoxide dismutase (SOD), creatine kinase (CK), Na＋/K＋-ATPase, lactate dehydrogenase (LDH), malondialdehyde (MDA), glutathione peroxidase (GSH-Px)) in Epinephelus septemfasciatus embryos were studied. In the present study, the changes of enzyme activity in embryos were analyzed by kits to clarify damage mechanism of embryos. The results indicated that the MDA enzyme activity of embryos after cryopreservation treated with the vitrifications solution of PM(24% 1,2 - propylene glycol(PG)＋16% methanol(MeOH))、PMG(15.75% pylene glycol(PG)＋8.75% methanol(MeOH)＋8.75% glycerol(Gly))和PMGT(15.75% pylene glycol(PG)＋8.75% methanol(MeOH)＋8.75%glycerol(Gly)＋5% Trehalose) significantly increased compared with no cryopreservation groups. However, the activity of some other enzymes descended significantly before and after cryopreservation compared with control group (P<0.05), and the latter was significantly lower than the former. However, there was no significant difference between Na＋/K＋-ATPase enzyme activity of no-frozen embryos treated with PM vitrification group and the control group. From various enzymes activity change from seven-band grouper before and after cryopreservation, cryopreservation and cryoprotectants have significant effect on the enzymes activity of seven-band grouper. Therefore, through the detection and analysis of the concentration of enzymes activity change from frozen embryos, freeze made MDA enzymes activity increase, other 5 enzymes activity decreased. PM vitrification solution had less effect on CK and Na＋/K＋-ATPase, which showed it had certain protective function. Therefore, the research results provide a theoretical basis for cryopreservation of seven-band grouper embryos.
