The maternally provided histone demethylase LSD1/KDM1A has an instrumental role at the beginning of life, shaping the histone methylation landscape and the transcriptional repertoire of the early mouse embryo.
Drosophila melanogaster embryos undergo a dramatic genomic transformation in the hour preceding gastrulation, as thousands of promoters and regulatory regions become biochemically distinct before they become active.
Soon after fertilisation, a critical portion of the embryonic genome is switched on through the actions of maternally inherited Stella, in part through controlling the activation of transposable elements.
ME31B is a general repressor of gene expression in the Drosophila early embryo, repressing translation before the maternal-to-zygotic transition and stimulating mRNA decay after activation of the zygotic genome.
In fruit flies, maternally deposited RNA-binding proteins are removed during the maternal-to-zygotic transition via a mechanism of translational upregulation of Kondo, the key E2 enzyme, at egg activation.