Fig 6.

Corticosteroids used for DBA treatment may act by downregulating p53 and its targets and in this way shifting cellular homeostasis to more normal conditions. Adult zebrafish heterozygous for rpl11 mutation were mated and the embryos were treated with 100 ng/ml dexamethasone from 2 hpf. The embryos were collected at 32–84 hpf and divided into mutant and sibling groups. (A) Expression of tp53, cdkn1a and puma mRNA was downregulated in mutants treated with dexamethasone. qPCR, fold change is shown as ratio to sibling controls. Each group had at least 30 embryos. (B) runx1 expression is downregulated in mutants and its expression was rescued by dexamethasone treatment. 32 hpf, In situ hybridization. (C) rpl11 mutants have few red blood cells at day 3·5 as estimated by staining with dianizidine. Treatment with dexamethasone led to the increase in number of red blood cells. Representative of two independent experiments are shown.