Knockdown of wt1a and wt1b induces different phenotypes. (A) After injection of control, wt1a and wt1b morpholinos, RT-PCR analysis was performed from total RNA (10 pooled embryos from each injection). Both wt1a and wt1b primer pairs (indicated by arrows) are composed of a forward primer lying in the respective exon 1 and a reverse primer lying either in exon 2 (top panels) or in intron 1 (bottom panels). (B) Quantitative real-time RT-PCR was performed from total RNA of injected and pooled embryos at the indicated stage using primer pairs as described in panel A located in exon 1 and exon 2 of wt1a (upper panel) or wt1b (lower panel), respectively. All values were normalized to beta-actin. For comparison, expression in 1-day-old control embryos was set to 1. (C) Control, wt1a and wt1b morpholino-injected embryos are shown at different stages. Pericardial edema is marked by arrows and yolk sac edema by arrowheads; wt1a-MO, wt1a exon 1–intron 1 splice morpholino; wt1b-MO, wt1b exon 1–intron 1 splice morpholino; hpf, hours post-fertilization; dpf, days post-fertilization.