Comparative analysis of H3K9 acetylation level in parthenogenetic, and in vitro and in vivo developed mouse embryos.

The developmental rate of parthenogenetic embryos is slower than that of embryos generated in vitro and in vivo. To detect the effects of epigenetic modification on embryo development, we compared the H3K9 acetylation level in these three types of embryos as well as parthenogenetic embryos treated with a histone deacetylase inhibitor trichostatin (TSA) by indirect immunofluorescence. Our results showed that fluctuations in the level of acetylated H3K9 detected during embryo development are similar among different types of mouse embryos. However, the level of H3K9 acetylation in parthenogenetic embryos is significantly higher while the level in embryos generated in vitro is lower when compared with that in embryos derived from in vivo. Treatment of parthenogenetic embryos with TSA increases the developmental rate but further elevates the level of H3K9 acetylation, especially from pronuclear to 8-cell stages. These results suggest that the promoters of genes that should be silenced during pre-implantation embryo development may be hyperacetylated in parthenogenetic embryos which inhibit normal embryo development. However, the positive effect of TSA on embryo development is not through altering the H3K9 acetylation level.