Fig. 2

Craniofacial development is sensitive to early elevation of Zic2a levels. Alcian blue-stained cartilage in heat-shocked Tg(hsp70l:Gal4VP16);Tg(11XUAS:zic2aYFP) embryos at 5 dpf. (A,E) Heat shock (HS)-induced misexpression of Zic2aYFP at 10 hpf has a variable effect on craniofacial cartilage, ranging from shortened mandibular and hyoid arches (45/51, 5 exp., shown in 2E) to absence of all anterior cartilages (5/51, 5 exp.). (B,F) Zic2aYFP induction at 14 hpf has a similar effect, causing hypoplastic pharyngeal cartilages (29/36, 3 exp., shown in 2F) or ablation (7/36, 3 exp.). (C,G) Zic2aYFP induction at 17 hpf causes less penetrant pharyngeal cartilage hypoplasia in overexpressors (12/24, 2 exp.). (D,H) Zic2aYFP induction at 24 hpf has no effect on craniofacial cartilage (57/62, 4 exp.). (I,J) 10 hpf HS causes a narrowing of the space between trabecular cartilages (13/53, 4 exp., asterisk in 2J) or complete fusion (16/53, 4 exp.). (K,L) Zic2aYPF induction at 14 hpf causes fusion of the trabeculae (asterisk in 2L) and absence of the ethmoid plate (10/19, 1 exp., arrow in 2L), or ablation of the entire anterior neurocranium (5/19, 1 exp.). (M,N) Penetrance of cartilage defects following Zic2aYFP induction at specified timepoints. (A–H) are dissected pharyngeal cartilages, dorsal views, anterior to the left. (I–L) are dissected neurocranial cartilages, dorsal views, anterior to the left. Abbreviations: cb—ceratobranchials, ep—ethmoid plate, h—hyoid arch, m—mandibular arch, t—trabecular cartilages.