Genome activation in equine in vitro-produced embryos.

Area of Science:

• Reproductive Biology
• Developmental Biology
• Genomics

Background:

• Embryonic genome activation (EGA) is crucial for initiating the embryo's own transcription.
• Understanding EGA timing and regulation is vital for species-specific embryo development.
• In vitro embryo production in horses is growing, but EGA knowledge is limited.

Purpose of the Study:

• To determine the timing of embryonic genome activation in vitro-produced horse embryos.
• To identify the transcriptional networks governing early equine embryonic development.

Main Methods:

• RNA-Sequencing (RNA-Seq) was used on horse oocytes and embryos at eight developmental stages.
• Co-expression network analysis identified gene groups regulated by common mechanisms.
• Analysis of hub genes and promoter binding motifs implicated key transcription factors.

Main Results:

• Initial gene transcription was observed at the 2-cell stage.
• Minor EGA occurred at the 4-cell stage, with major activation at the 8-cell stage.
• Increased intronic nucleotides at the 4-cell stage indicated transcription initiation.

Conclusions:

• This study provides the first genomic evaluation of EGA in horse embryos.
• Identified key stages (4-cell and 8-cell) and transcriptional regulators of equine EGA.
• Findings contribute to understanding and improving equine embryo production.