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Fig. 4 Misexpression of SoxE genes differentially rescues NC sublineage specification and differentiation in foxd3zdf10;tfap2aMO embryos. (A,E,H) sox9a and sox9b (sox9a/b) RNA co-injection with tfap2a morpholino (tfap2aMO) into foxd3zdf10 mutant embryos (foxd3zdf10-tfap2aMO). (A) Live 4 dpf larva, dorsal view, anterior to the left. Melanophore and xanthophore development is rescued in foxd3zdf10-tfap2aMO embryos co-injected with sox9a/b RNA (arrows; compare with wild-type embryo, D). (E) Alcian Blue staining of a 4 dpf larva, vental views with anterior to the left. Misexpression of sox9a/b in foxd3zdf10-tfap2aMO embryos results in rescue of the neurocranium, as well as of the mandibular and hyoid jaw structures. (H) dlx2 expression at 24 hpf, dorsal views, anterior to the left. Specification of NC craniofacial progenitors occurs in foxd3zdf10-tfap2aMO embryos co-injected with sox9a/b RNA, based on dlx2 expression (arrows). (B,F,G,I,J) foxd3zdf10-tfap2aMO embryos co-injected with sox10 RNA. (B) Live 4 dpf larva, dorsal view, anterior to the left. Consistent with a role in development of non-ectomesenchymal NC derivatives, sox10 misexpression rescues melanophore and xanthophore development in foxd3zdf10-tfap2aMO embryos (arrows; compare with wild-type embryo, D). (F) Alcian Blue staining of 4 dpf larva, ventral view, anterior to the left. sox10 misexpression does not rescue cranial cartilage structures in foxd3zdf10-tfap2aMO embryos. (G) 16A11 immunoreactivity, 3 dpf, dorsal view. Dorsal root ganglion neuron development is rescued by sox10 misexpression (arrowheads). (I) dlx2 expression at 24 hpf, dorsal view with anterior to the left. sox10 RNA injection also does not rescue NC dlx2 expression in foxd3zdf10-tfap2aMO embryos (asterisks), indicating that sox10 function cannot rescue the specification of NC precursors for craniofacial cartilages. (J) th expression at 48 hpf, lateral view, anterior to the left. sox10 misexpression rescues sympathetic neuron development (arrow). (C) Live 4 dpf larva, dorsal view, anterior to the left. Morpholino-mediated knockdown of p53 in foxd3zdf10-tfap2aMO embryos rescues melanophore, xanthophore (arrows; compare with wild-type embryo, D) and iridophore (not visible) development. (K-M) sox10-responsive NCCs persist in foxd3zdf10-tfap2aMO embryos. 33 hpf embryos, lateral view, anterior to left. (K) Wild-type embryo with abundant melanophores. (L) In foxd3zdf10-tfap2aMO embryos injected with a heat shock-inducible sox10 construct but not exposed to heat shock, melanophores fail to develop. (M) In foxd3zdf10-tfap2aMO embryos injected with a heat shock-inducible sox10 construct and heat shocked at 24 hpf, robust melanogenesis occurs.