Fig. 6

H3.3 functions at the NPB–CNC transition.

a–f, Expression of msxb, pax3a, zic2a, and tfap2a at 10 hpf and msxb and pax3a at 11 hpf is indistinguishable between wild types and both homozygous and heterozygous h3f3a^db1092 mutants (mut) (n≥10 for each). g–k, At 11 hpf, both homozygous and heterozygous h3f3a^db1092 mutants have severe reductions in the expression of snai2 (4/4 mut; 0/4 wt), sox10 (10/12 mut; 0/6 wild-type), foxd3 (9/9 mut; 0/5 wt), tfap2a (7/7 mut; 0/4 wt), and sox9b (8/8 mut; 0/3 wt). l, sox10 expression is also lost in embryos injected with D123N (10/12) but not wild-type (0/16) h3f3a mRNA. m, In both homozygous and heterozygous h3f3a^db1092 embryos, sox10 expression partially recovers by 16.5 hpf yet is specifically reduced in presumptive CNC ectomesenchyme domains (arrows) (6/6 mut; 0/4 wt). An increase in sox10-positive cells is evident in the mutant dorsal neural tube (insert) between the sox10-positive otic placodes (arrowheads) which are unaffected in mutants. n, At 16.5 hpf, dlx2a expression in three streams of migrating ectomesenchyme is reduced in both homozygous and heterozygous h3f3a^db1092 mutants (6/7 mut; 0/5 wt). o, The 16.5 hpf ectomesenchyme expression (arrows) of twist1a is reduced in both homozygous and heterozygous h3f3a^db1092 mutants yet paraxial mesoderm expression is unaffected (white arrowheads) (8/8 mut; 0/5 wt). In all panels, homozygous h3f3a^db1092 examples are shown. All images are dorsal views with anterior to the left. Scale bars: 250 μm.