Fig. 1

Partial knock-down of appb. Injection of 2.5 ng morpholino (MO) designed against appb results in an undulating notochord (B, dashed line) not present in animals injected with control MO at 24 hpf (A). Otherwise, the gross morphology of embryos injected with control (C) or appb morpholino (D) is comparable at 48 hpf. Cells within the notochord of appb morphants (F) are less vacuolated compared to controls (E). RT-PCR amplification of exon 1 and 4 (G,H) results in a larger fragment in embryos injected with appb morpholino than control morpholino (G). At 2.5 ng approximately 50–60% of the wildtype transcript was present, whereas it was absent at 5 ng morpholino. (H) Schematic illustration of wildtype and trslMO splicing (upper) and the effect of the appb morpholino (blue comb) on splicing. Blocking the splicing of intron 2 activates an alternative splice site (N) within intron 2 resulting in a premature stop in exon 3 (H). Scale bar: 20 μm.