Fig. 4. Forced activation of Notch signaling in the ectoderm represses expression of head-fold markers. Electroporation of GFP (A,B,G,H), GFP+CNIC (C,D) and GFP+CNIC^C89 (E,F,I,J) was performed on stage 6 embryos, and the embryos were cultured for 7 hours until stage 9. Transfected areas are visualized by the fluorescence of GFP overlaid on bright field image of electroporated live embryos (A,C,E,G,I). Slug and Pdgfr expression in the head fold (B,D,F,H,J) are shown at higher magnification, corresponding to the boxed areas of A,C,E,G,I, respectively. Forced activation of Notch signaling by CNIC and CNIC^C89 (cytoplasmic domain of chicken Notch1) reduced the expression of Slug and Pdgfr in the head fold (arrowheads in D,F,H).