Oxygen concentration affects de novo DNA methylation and transcription in in vitro cultured oocytes

We optimised an in vitro culture model for mouse oocytes starting from immature oocytes to get mature oocytes and investigated the effect of oxygen concentrations on the cultured oocytes (5 % vs 20% oxygen). The cultured oocytes were size-selected in both conditions. We generated expression and methylation profiling (RNA-Seq, RRBS, PBAT) by high throughput sequencing from these size selected oocytes and compared the results with in vivo size oocytes. Our observations reveal changes in DNA methylation and transcripts between oocytes cultured in vitro with different oxygen concentrations and in vivo grown murine oocytes. Oocytes grown under 20% O2 had a higher correlation with in vivo oocytes for DNA methylation and transcription demonstrating that higher oxygen concentration is beneficial for the oocyte maturation in ex-vivo culture condition. RNA-Seq, PBAT and RRBS in mouse cultured oocytes at different sizes under 2 different conditions of in vitro culture (5% oxygen vs 20%oxygen)