Expression of Apoptotic and Antioxidant Enzyme Genes in Sheep Oocytes and In Vitro Produced Embryos

The present study was to find out the expression pattern and relative expression level of apoptotic (Bcl2, Bax, Casp3, and PCNA) and antioxidant enzyme [(GPx, Cu/Zn-SOD (SOD1) and Mn-SOD (SOD2)] genes in sheep oocytes and developing embryos produced in vitro by conventional RT-PCR and real time qPCR, respectively. Different developmental stages of embryos were produced in vitro from oocytes collected from local slaughter house ovaries. RT-PCR amplicons showed expression of Bcl2 and PCNA in all stages except at morula. In contrast Bax and Casp3 were expressed in all stages. GPx and SOD1 were expressed in all stages but SOD2 was not expressed in 8-16 cells, although expressed in the remaining stages. The qPCR analysis reflected that Bcl2 expression was significantly (P < 0.05) downregulated in morula and maximum upregulated expression was observed in in vitro matured oocytes. Higher upregulated expression (P < 0.05) of Bax was in morula and downregulated expression was at 2-4 cells. Casp3 was significantly upregulated at 8-16 cells and downregulated in in vitro matured oocyte. PCNA expression was highest at blastocyst and least expression was at morula. GPx was expressed significantly highest in matured oocytes and least expression was at zygote. SOD1 was expressed significantly highest at 8-16 cells and least expression was at zygote. Expression of SOD2 was least among all the antioxidant enzymes but significantly higher expression of SOD2 was in immature oocyte; however, least expression was at 8-16 cells. It can be concluded from the study that the sheep embryos produced in vitro are highly sensitive to culture condition, which alters the expression level of apoptotic and antioxidant enzyme genes.