Relationship Between Differential Expression of Bax and Bcl-2 Genes and Developmental Differences of

The developmental competence of porcine parthenotes cultured in porcine zygote medium-3(PZM-3) and North Carolina State University-23(NCSU-23) media was investigated.After in vitro maturation oocytes were electro-activated,and the subsequent developmental competence,rates of apoptotic,fragmented and arrested embryos from the two media were evaluated.Also,the ratio of mRNA expression of Bcl-2 and Bax gene was determined.Results demonstrated that cleavage,blastocyst,hatched blastocyst rates,and blastocyst cell numbers were significantly higher in PZM-3 than in NCSU-23.The rate of fragmented embryos in PZM-3 was lower than in NCSU-23 on d 1 and 3(P<0.05) while the percentage of arrested embryo was lower in PZM-3 than in NCSU-23 on d 4 and 5(P<0.05).TUNEL positive signals were higher in NCSU-23 than in PZM-3 from d 3 to 7(P<0.05).The ratios of Bcl-2 and Bax mRNA expression in embryos were higher on d 5 than on d 3 and 1 in PZM-3(P<0.05).In contrast,the ratios of Bcl-2 and Bax mRNA expression in embryos on d 1 were higher than on d 3 and 5 in NCSU-23(P<0.05).Additionally,the ratios of Bcl-2 and Bax mRNA expression in embryos in PZM-3 were higher than in NCSU-23 on d 3 and 5(P<0.05).In conclusion,lower apoptotic embryo rates and down-regulating Bax together with up-regulating expression of Bcl-2 transcripts may be responsible for the better developmental competence of porcine parthenotes in PZM-3.