Fig. 2. Ezh2 depletion disrupts histone H3 methylation in zygotes and early embryos. (A) Wild-type zygotes at 0-3 hpf show histone H3-me₃-K27 methylation of the maternal pronucleus and of the PB. In the Ezh2-depleted zygote, H3-K27 methylation is markedly reduced (right panels). The H3-K9 shows a similar staining to H3-K27 but H3-K4 methylation is unchanged in Ezh2 depleted embryos (not shown). (B) A four-cell embryo with equal staining of all nuclei for H3-K27. In embryos depleted of maternally inherited Ezh2 (middle panel), the H3-27 is substantially less than in wild-type embryos (left panel). The H3-K27 levels are restored in these embryos at 16- to 32-cell stage (far right panel). Bottom row, green shows antibody staining; middle row, DNA staining in red (propidium iodide); top row, merged images.