Inhibition of p53 partially restored erythroid levels at later stages of development. Rpl11 morpholino was injected in p53-null zebrafish embryos. (A) Morphology of p53-null zebrafish embryos at 24 hpf. The arrowhead indicates the recovery of aplasia in the head. (B) Transcript quantification for p53 and genes downstream of p53: mdm2, p21, bax, and puma at 24 hpf. (C, top) Morphology of p53-null zebrafish embryos at 48 hpf. The arrowhead points to the presence of a smaller head, edema, and defective yolk extension. (C, bottom) o-Dianisidine staining of embryos reveals lack of hemoglobin-positive cells. (D) o-Dianisidine staining of wild-type (WT) (top) or p53-null (bottom) embryos at 72 hpf. The arrowhead points to the recovery of erythroid cells in p53-null embryos. Observed phenotype (D): WT + rpl11 MO = 40/40 p53(^−/−) + rpl11 MO = 30/40.