Fig. 4. The kar gene product, Ece2, acts outside pigment cells to promote iridophore development.

Wild-type (A) and nac;pfe mutant (B) adult fish for comparison. Transplantations of kar mutant cells into strong rse (C) or nac;pfe (D) mutant recipients result in fish with recovered stripe patterns. In chimeric fish generated by transplantation of nac;pfe donor cells into kar mutant recipient embryos (E,E′) occasionally, very small patches of dense iridophores develop (magnification in E′, white arrows). In the vicinity of these patches melanophores increase in number (black arrow). Labelling of the donors with Tg(β-actin:GFP) (F,F′) shows transplanted donor cells of various cell types next to the patches of dense iridophores.