Melanogenesis gene expression is reduced in crasher (ap3d1) mutants. (a, b and e) dct expression at 24 hpf is reduced in 1/4 of crasher heterozygote progeny (b) as assessed by a chi-square goodness-of-fit test to a 3 wild-type phenotype:1 mutant phenotype ratio (χ2 = 1.08, χ = 3.84, p = 0.30). dct + cell number is significantly reduced in mutant phenotype fish at 24 hpf (Student's t-test, t = 2.83, p = 0.03*). (c, d and f) dct expression is reduced in the crasher clutch overall by 30 cells on average at 30 hpf (Student's t-test, t = 2.39, p = 0.02*). (f) crasher clutch cell counts at 30 hpf segregate into a 3:1 ratio (χ2 = 1.61, χ = 3.84, p = 0.20). (g–l) tyr is not significantly reduced at 24 hpf (Student's t-test, t = 0.90, p = 0.38) (g, h and k), but is slightly reduced at 30 hpf in the crasher clutch (Student's t-test, t = 2.14, p = 0.04*) (i, j and l). (m-r) tyrp1b + cells are reduced at 24 hpf in the crasher clutch (Student's t-test, t = 3.51, p = 8.73 × 10−4***), but no obvious mutant phenotype is observed (m, n and q). At 30 hpf, tyrp1b + cells are significantly reduced (Student's t-test, t = 2.66 p = 0.01**), but no obvious mutant phenotype is observed (o,p, and r). (s) Expression heatmap of melanogenesis genes at 3 dpf using RNA-Seq. tyrp1b is reduced by >twofold (log2 fold difference of 1), while dct is also reduced. tyr expression is slightly increased. mitfa expression is not altered. (a, b, g, h, m and n) Scale bars are 500 μm. (c, d, i, j, o and p) Scale bars are 1 mm. tyrp1b 24 hpf and tyr 30 hpf experiment repeated twice. dct 30 hpf experiment repeated once. Plots are violin box plots. Images labeled ‡crasher are representative fish from the clutch.