An integrated platform for bovine DNA methylome analysis suitable for small samples

Area of Science:

• Epigenetics
• Genomics
• Mammalian Development

Background:

• Studying early mammalian development is challenging due to limited sample material (DNA, RNA, proteins) in oocytes and embryos.
• The DNA methylome, a key epigenetic layer, is crucial for understanding embryonic development.
• Previous methods required significant sample amounts, hindering studies on minute biological samples like early embryos.

Purpose of the Study:

• To introduce a novel, optimized platform for genome-wide DNA methylation analysis in bovine early embryos.
• To enable integrated analysis of DNA methylome and transcriptome data from the same biological sample.
• To facilitate the study of bovine sperm and blastocyst epigenomes.

Main Methods:

• Development of a comprehensive platform for genome-wide bovine DNA methylation analysis.
• Optimization of procedures for analyzing minimal DNA input (10 ng from 10 bovine blastocysts).
• Integration of DNA methylome and transcriptome data processing pipelines.
• Comparative analysis of DNA methylation patterns between bovine sperm and blastocysts.

Main Results:

• Confirmed hypermethylation in bovine sperm DNA compared to early embryo genomes.
• Identified differentially methylated regions in sperm across various genomic features, including promoters, introns, exons, and repetitive elements.
• Observed distinct methylation patterns in CpG islands, with blastocysts showing higher methylation in high-density CpG islands, while sperm showed higher methylation in LTR, LINE, and SINE elements.

Conclusions:

• This represents the first platform for genome-wide epigenetics compatible with early bovine embryos.
• The platform is expected to advance research into epigenetic risks associated with assisted reproductive technologies (ART).
• It will aid in understanding embryonic cell line establishment and identifying epigenetic deviations impacting gene expression and long-term development.