Fig. 7. piy-mediated apoptosis depends on the ATM-Chk2-p53 pathway. (A) Quantitative PCR analysis of p53 mRNA in wild-type and piy mutant zebrafish embryos. There is no difference in the amplification of a control gene, ef1 (lower panel), from wild-type and the piy mutant cDNA pools. By contrast, the p53 gene is amplified from the piy mutant cDNA pool by a smaller number of PCR cycles than from the wild-type cDNA pool (upper panel), suggesting that p53 mRNA is more abundant in the piy mutant embryos than in wild-type embryos. (B,C) Plastic sections of piy mutant retinas injected without (B) and with (C) MO-Chk2. (D,E) Plastic sections of piy mutant retinas injected without (D) and with (E) MO-p53. (F-H) Treatment of the piy mutant embryos with DMSO (F), KU55933 (G) or CGK733 (H). (I-K) Labeling of wild-type sibling (I), piy mutant (J) and MO-p53-injected piy mutant (K) retinas with the zn5 antibody, which labels RGCs (red). All nuclei are counterstained with Sytox Green (green). (L-N) Labeling of wild-type sibling (L), piy mutant (M) and MO-p53 injected piy mutant (N) retinas with the zpr1 antibody, which labels double-cone type photoreceptors (red). (O-Q) Labeling of retinas of piy mutant (O), OKR-restored MO-p53-injected piy mutant (P) and OKR-restored MO-Chk2-injected piy mutant (Q) with anti-GABA antibody (red). GABA expression is normal in RGCs and amacrine cells in both MO-injected retinas.