Active demethylation of the paternal genome in the mouse zygote.

摘要: Abstract DNA methylation is essential for the control of a number biological mechanisms in mammals [1]. Mammalian development accompanied by two major waves genome-wide demethylation and remethylation: one during germ-cell other after fertilisation [2–7]. Most previous studies have suggested that observed occurs passively, is, lack maintenance following replication cell division [6,7], although study has reported replication-independent may also occur early embryogenesis [8]. Here, we report genes are highly methylated sperm rapidly demethylated zygote only hours fertilisation, before first round commences. By contrast, oocyte-derived maternal alleles unaffected this reprogramming. They either remain or become further de novo . These results provide direct evidence active single-copy mammalian and, moreover, reveal striking asymmetry epigenetic Whereas paternally (sperm)-derived sequences exposed to putative demethylases oocyte cytoplasm, maternally (oocyte)-derived protected from reaction. results, whose generality supported findings Mayer et al. [9], important implications establishment biparental genetic totipotency genomic imprinting, reprogramming somatic cells cloning.