Fig. 6. PIE-1, SKN-1 and MED-1 expression in spn-4 embryos. PIE-1::GFP is segregated to the posterior daughter of P₁ at the 4-cell stage in live wild-type embryos (A,C) and in live spn-4(RNAi) embryos (B,D). PIE-1::GFP localizes to centrosomes during mitosis (A,B) and to nuclei in older four-cell stage embryos (C,D). In wild-type embryos, SKN-1 protein was detected with a mAb at high levels in P₁ and its daughters (E,G). In fixed 2-cell stage spn-4(or80) mutant embryos, SKN-1 is present at high levels in P₁ in some embryos (F; see text). At the four-four cell stage, SKN-1 is present only in P₁ descendants in fixed wild-type embryos (G). SKN-1 is present at high levels throughout a fixed spn-4(or80) embryo (H). In live wild-type embryos, MED-1::GFP is expressed zygotically in the two daughters of EMS. In live spn-4(RNAi) embryos MED-1::GFP in the two daughters of the anterior daughter of P₁ (F). PIE-1 and SKN-1 micrographs were obtained using confocal microscopy, MED-1::GFP micrographs were obtained using epifluorescence microscopy.