Fig. 8. Kermit 2/XGIPC is required for cell survival, but not for cell proliferation in Xenopus. (A-F) Control morpholino (A), kermit 2 morpholino alone (B,E,F), kermit 2 morpholino with 3 ng of kermit 2 mRNA (C) or 1 ng of DN-IGFR (D) was injected into the right side dorsal animal blastomere of four-cell/eight-cell embryos. The left side serves as a control. TUNEL staining and phosphorylated histone H3 staining were performed on neurula stage embryos. Embryos are viewed from the dorsal side, anterior towards the top. Compared with the control side (left side), the side injected with kermit 2 morpholino (right side) shows a substantial increase in the number of TUNEL-positive nuclei (B), without apparent change in the number of mitotic cells (E,F). The increased apoptosis in kermit 2-depleted embryos can be rescued by co-expression of kermit 2 mRNA lacking the 5'UTR (C). DN-IGFR also leads to elevated cell death on the injected side, as shown in D. (G-I) Co-injection of Bcl2 mRNA recovers Pax6 eye expression in kermit 2-depleted embryos. Microinjections were performed as above and nß-gal was used as the lineage tracer. Embryos were fixed at stage 20 and ß-galactosidase activity was measured in situ (red) followed by whole-mount in situ hybridization for Pax6. Red arrowhead in H indicates strongly reduced eye region in kermit 2 morpholino-injected embryo and red arrow in I indicates recovered eye expression domain by Bcl2 mRNA.