Fig. 2

 Development of neural crest-derived chromatophores in sym1 mutants. Lateral views of living wild-type (A, B) and sym1 mutant (C, D) embryos at 3 dpf. Melanophores (black) are evident in both wild-type (A) and sym1 (C) mutant embryos, although sym1 mutants have more dorsally-displaced melanocytes on the trunk (arrow) and yolk (arrowhead; see also panel L). Incident light reveals silver iridiphores are reduced in some sym1 mutants (D). Lateral views of developing melanoblasts expressing mitf in wild-type (E, F) and sym1 mutant (G, H) embryos. F and H are higher magnification views of the trunk region in E and G. Arrowheads in E–H indicate the posterior extent of mitf staining along the trunk in wild-type and sym1 mutants, while the arrows in E–H show the posterior extent of dorsal–ventral neural crest migration, both of which are delayed in sym1 mutants (compare E, F with G, H). Expression of dct at 36 hpf in wild-type (I) and sym1 mutant (J) embryos. The expression pattern and numbers of dct-positive cells are indistinguishable between wild-type and sym1 mutants. Quantitation of melanophore numbers (K) and distribution (L) in wild-type (red) and sym1 mutants (blue). Abbreviations: mitf (microphthalmia-associated transcription factor), dct (dopachrome tautomerase).