Otic expression of fgf genes following mis-expression of fgf3 or inhibition of Hh signalling.
(A–F’) In situ hybridisation for otic expression of fgf genes in Tg(hsp70:fgf3) embryos following a 30-minute heat shock (HS) at the 10-somite stage (14 hpf). Controls (left-hand panels of each pair of images) were sibling non-transgenic (Non-Tg) embryos subjected to the same heat shock. Numbers of embryos shown in the dorsal view panels indicate the number showing the phenotype from a mixed batch of transgenic and non-transgenic embryos in each pair of panels; 75% of the batch is expected to be transgenic. A–B’ show staining with a probe specific to the 3’ UTR of fgf3: note the ectopic patch of endogenous fgf3 expression at the posterior otic pole (B,B’; arrowheads) and disruption to fgf3 expression ventral to the otic vesicle (B’; asterisks) after heat shock in transgenic embryos. Expression of fgf10a is strengthened in the otic vesicle of transgenic embryos after heat shock (E–F’). (G–Q’) Expression of mRNA for fgf genes in embryos treated with 100 μM cyclopamine (cyc) from the 10-somite stage (14 hpf) until 22.5 hpf. Controls in the left-hand panels of each pair of images were treated with vehicle (ethanol) only. Numbers of embryos with the phenotype shown for individual treatments are indicated in the dorsal view panels. There was little change to the otic expression patterns of fgf3 or fgf8a at 22.5 hpf (8.5 hours post treatment) (G–J’), but note the loss of fgf3 expression ventral to the ear (H’; asterisk). Expression of fgf10a in the otic vesicle was strengthened after inhibition of Hh signalling in about 50% of treated embryos (L,L’). At 36 hpf (8.5 hpt + 13.5 h wash), ectopic expression of both fgf3 and fgf8a appeared in a new posteromedial domain in the ears of cyclopamine-treated embryos (M-P’; arrowheads). (Q,Q’) Expression of fgf8a in the posterior of the otic vesicle at 48 hpf (8.5 hpt + 25.5 h wash). Ectopic expression has strengthened (arrowhead) and medial epithelium is thinner than normal (brackets). Dorsal views of the left ear, with anterior to the top. Scale bar in A, 50 μm (applies to A–L); scale bar in A’, 50 μm (applies to A’–L’); scale bar in M, 50 μm (applies to M–P); scale bar in M’, 50 μm (applies to M’–P’); scale bar in Q, 20 μm (applies to Q,Q’).