Genome activity during the emergence of mouse embryonic totipotency (time course)

Fertilization transforms sperm and egg into a totipotent embryo but the underlying mechanisms are unknown. We here report that gene expression initiates during the gamete-to-embryo transition in mouse embryos. Meiotic exit induced by sperm entry enhances a transcriptionally-permissive epigenetic landscape. Time-course analysis of single embryos revealed a succession of genome-wide transcription 'ripples' initiating within 2 hours. Disrupting key pluripotency transcription factor levels prior to sperm entry had little immediate effect, indicating that different mechanisms engender pluripotent and totipotent states. These findings suggest that a hierarchical gene expression program characterizes the emergence of totipotency during the gamete-to-embryo transition, with broad mechanistic implications for the reprogramming of cellular potency. 2h interval time course after ICSI produced mouse single embryo: Biological replicates: 3 replicates at 0h, 3 replicates at 2h, 4 replicates at 4h, 3 replicates at 6h, 3 replicates at 8h, 4 replicates at 10h, 4 replicates at 12h