Parallel bimodal single-cell sequencing of transcriptome and methylome provides molecular and translational insights on oocyte maturation and maternal aging

Advanced maternal aging has become a worldwide public health issue contributing to female fertility decline. To provide a complete landscape of transcriptome and epigenetic changes during oocyte aging and maturation, we applied a parallel bimodal genomics approach to parallel transcriptome and methylome profiles of mouse oocytes at single-cell and single-base resolution. Age-associated gene expression changes were associated with defective spindle assembly and mitochondrial dysfunction. Parallel sequencing data suggested aged-related defects in mRNA degradation and methylome remodelling during oocyte maturation. Differentially methylated region in aged mature oocyte was associated with trimethylation of Histone H3 at Lysine 4. More importantly, RNA expression-based prediction model for assessing maturation and oocytes age. Taken together, our work provides a better understanding of molecular mechanisms during mouse oocyte aging, points a new direction of oocyte quality assessment and paves the way for developing novel treatments to improve oocyte quality.