RESEARCH ARTICLE Genome-Wide DNA Methylation Patterns of Bovine Blastocysts Developed In Vivo from Embryos Completed Different Stages of Development In Vitro

Early embryonic loss and altered gene expression in in vitro produced blastocysts are believed to be partly caused by aberrant DNA methylation. However, specific embryonic stage which is sensitive to in vitro culture conditions to alter the DNAmethylation profile of the resulting blastocysts remained unclear. Therefore, the aim of this study was to investi-gate the stage specific effect of in vitro culture environment on the DNA methylation response of the resulting blastocysts. For this, embryos cultured in vitro until zygote (ZY), 4-cell (4C) or 16-cell (16C) were transferred to recipients and the blastocysts were recovery at day 7 of the estrous cycle. Another embryo group was cultured in vitro until blastocyst stage (IVP). Genome-wide DNA methylation profiles of ZY, 4C, 16C and IVP blastocyst groups were then determined with reference to blastocysts developed completely under in vivo condition (VO) using EmbryoGENE DNAMethylation Array. To assess the contribution of methylation changes on gene expression patterns, the DNAmethylation data was superim-posed to the transcriptome profile data. The degree of DNAmethylation dysregulation in the promoter and/or gene body regions of the resulting blastocysts was correlated with succes