Elevated levels of maternally derived CYCB promote premature mitosis at the MBT. The percentage of embryos (n, number of embryos analyzed) derived from the indicated crosses (beneath) that display a premature mitosis 14 phenotype. Progeny derived from Capr2, +/Df, dfmr13 females receiving either a CycB2 (light-gray bar, GFP–) or GFP-marked (dark-gray bar, GFP+) paternal chromosome displayed the premature mitosis 14 phenotype at similar frequencies. The reduction of maternal CycB mRNA partially rescues the precocious mitosis 14 phenotype (left panel, far right-hand bar), whereas the reduction of zygotic CycB mRNA does not (right panel, GFP–).