Appropriate epigenetic changes in preimplantation embryos are critical for embryonic development and successful pregnancy. The aim of this study was to evaluate the effects of superovulation, vitrification and in vitro culture on expression of enzymes involved in DNA methylation and imprinted genes in blastocysts and E9.5. Results showed that vitrification decreased the developmental competence of embryos cultured in vitro ( P 0.05). Assisted reproductive techniques influenced most imprinted genes expression in the blastocysts ( P 0.05). In next step, this perturbed mRNA expression restrict to E9.5 superovulated fetuses (3 of 5 imprinted genes). It is likely that hormonal stimulation in the superovulated mice alters the environment of the uterus, which adversely affects the normal epigenetic patterns of the resultant. In last experiment, knockdown of DPPA3 by injection of siRNA in germinal vesicle stage oocytes was used to assess its role in epigenetic remodeling. DPPA3 knockdown resulted in increased intensity of 5hmc staining in the maternal pronucleus (PN), demonstrating a role for this factor in the asymmetric remodeling of the maternal and paternal PN in bovine zygotes. Also, DPPA3 knockdown decreased the developmental competence of parthenogenetic and in vitro fertilized embryos. We conclude that DPPA3 have important role during early development which conserved between species. Key Words epigenetic, superovulation, vitrification, imprinted gene, DPPA3 knockdown
