RESUMEN
BACKGROUND: OBJECTIVE: This paper reports results from studies on modifications of histone marks in transcriptional regulatory regions of H19, Igf2 and Mest genes in vitrified-warmed and cultured mouse embryos. MATERIALS AND METHODS: Non vitrified and vitrified-warmed 8-cell embryos were cultured in Ham's F10+10% BSA into blastocyst stage in two experimental groups. Gene expression level was assessed by quantitative PCR and histone modifications were evaluated by ChIP assay method. RESULTS: The expression levels of the selected genes in vitrified embryos were found to be markedly reduced compared to the control group. Significant increase in H3K9me2 as a gene silencer was seen in the regulatory regions of all genes in vitrified group. Furthermore, H3K4me3 and H3K9ac decreased in some regulatory regions but not in all of them. Additionally, H3K9me2 in regulatory regions of Igf2 and H19 significantly increased in group I, whereas, there was no change in Mest compared to the control group. CONCLUSIONS: Vitrification and culture condition affects gene down regulation of Igf2 and H19. Although changes in each histone mark are not always the same as gene expression, the total pattern and sum of their changes are in line with gene down regulation upon vitrification and culture.
