Exposure of bovine oocytes to elevated insulin concentration (0.1 ug/ml) during in vitro maturation changes DNA methylation pattern in Day-8-blastocysts – an epigenetic study.. Bos taurus

The aim was to study the potential effect of hyperinsulinemia on gene expression and differential DNA-methylation of cow embryos by adding 0.1 µg/ml (INS0.1) during in vitro oocyte maturation. Overall design: In total, 882 abattoir-derived oocytes (equally distributed between treatments (INS0.1) and a control, (INS0)) produced 199 embryos in a period of 8 weeks. Cleavage blastocyst rates were recorded and embryos evaluated for stage and quality grade before individually frozen at -80 °C. 120 of the embryos were used for the methylome analysis, pooled in groups of 10 embryos with a similar distribution of embryos (pools adjusted for quality grade and developmental stage in order to avoid confounding effects in the results due to different embryo characteristics). The experiment was run in four replicates per treatment group.