Effect of Sex Differences of Donor Fetal Fibroblast on the Early Development and DNA Methylation Status of Buffalo (Bubalus Bubalis) Nuclear Transfer Embryos.

Contents Low efficiency of somatic cell nuclear transfer (SCNT) embryos is largely attributable to imperfect reprogramming of the donor nucleus. The differences in epigenetic reprogramming between female and male buffalo cloned embryos remain unclear. We explored the effects of donor cell sex differences on the development of SCNT embryos. We and then compared the expression of DNA methylation (5-methylcytosine-5mC and 5-hydroxymethylcytosine-5hmC) and the expression level of relevant genes, and histone methylation (H3K9me2 and H3K9me3) level in SCNT-female and SCNT-male preimplantation embryos with in vitro fertilization (IVF) counterparts. In the study, we showed that developmental potential of SCNT-female embryos was greater than that of SCNT-male embryos (p < 0.05). 5mC was mainly expressed in SCNT-female embryos, whereas 5hmC was majorly expressed in SCNT-male embryos (p < 0.05). The levels of DNA methylation (5mC and 5hmC), Dnmt3b, TET1 and TET3 in the SCNT-male embryos were higher than those of SCNT-female embryos (p < 0.05). In addition, there were no significant differences in the expression of H3K9me2 at eight-stage of the IVF, SCNT-female and SCNT-male embryos (p < 0.05). However, H3K9me3 was upregulated in SCNT-male embryos at the eight-cell stage (p < 0.05). Thus, KDM4B ectopic expression decreased the level of H3K9me3 and significantly improved the developmental rate of two-cell, eight-cell and blastocysts of SCNT-male embryos (p < 0.05). Overall, the lower levels of DNA methylation (5mC and 5hmC) and H3K9me3 may introduce the greater developmental potential in buffalo SCNT-female embryos than that of SCNT-male embryos.