Fig. S1

pnp4a expression is affected in early melanoblasts in mitfa mutants, and in presumptive iridoblasts, but not melanoblasts, in ltk mutants.

Chromogenic WISH at 24 hpf shows almost complete elimination of pnp4a expression from the NC derivatives of the dorsal trunk (vertical arrowheads) and the migratory pathways (arrows) of mitfa mutants (B, B’), compared to WT siblings (A, A’). Expression in the RPE domain is reduced (horizontal arrowheads). WISH at 30 hpf (C-D’) reveals persistence of pnp4a expression in migrating cells which we interpret as melanoblasts, in ltk mutants (asterisks), as well as in the multipotent progenitor domain of the posterior tail (vertical arrowheads). We also observe a reduced number of cells in iridoblast locations: overlying the RPE (horizontal arrowheads), in the developing lateral patches and along the dorsal posterior trunk (arrows, enlarged in C’,D’). At 48 hpf (E,F), the majority of pnp4a-positive cells in iridophore locations are absent in ltk mutants. Specifically, cells overlying the RPE (horizontal arrowheads), on the lateral patches and along the dorsal and ventral posterior trunk and tail (arrows) are dramatically reduced. Very few escaper iridophores (F, arrows) maintain strong pnp4a expression upon loss of ltk function. LP, lateral patches. Lateral views, heads positioned towards the left. Scale bar corresponds to 100 μm in A,B,C,D,E,F and to 50 μm in A’,B’,C’,D’.