Fig. 2

crasher mutant phenotype recapitulation using CRISPR knockout. (a) The crasher mutation maps to a ~ 375 kb region on chromosome 22. R = recombination event. (b–g) CRISPR ap3d1 knockout in *AB lines recapitulates the crasher phenotype. (b) Uninjected *AB control. (c) tyr gRNA injected *AB fish have mosaic tyrosinase activity. (d) crasher mutant with slight lightening of the retinal pigmented epithelium. (e) ap3d1 gRNA injected *AB fish display light, punctate crasher-like melanophores and a lighter retinal pigmented epithelium than crasher mutant. (f) Melanophore count boxplot in uninjected and injected tyr and ap3d1 fish. Melanophore number is reduced in both populations injected with gRNA (two-way ANOVA, guide F(1, 56) = 5.50, p = <0.02; injection status F(1, 56) = 247.50, p = <0.22 × 10⁻¹⁵; interaction F(1, 56) = 23.68, p = <9.68 × 10⁻⁶, Tukey HSD performed to determine group differences, p = <0.001***). (g) Boxplot shows iridophore number is unchanged between uninjected and injected for both guides (two-way ANOVA, injection status F(1, 56) = 0.02, p = 0.88; guide F(1, 56) = 46.05, p = 7.80 × 10⁻⁹; interaction F(1, 56) = 0.89, p = 0.35, Tukey HSD performed to determine group differences, p = <0.001***). Scale bar is 500 μm. 78 eggs injected for tyr; 58 eggs injected for ap3d1.