Melanophore <i>integrity</i> mutants show melanophore and iridophore defects.

<p>A, B) Dorsal, head images of live wildtype and mutant siblings, 5dpf. Wildtype melanophores maintain dark pigmentation and are now interacting with silver iridescent iridophores (present on eyes and in the center of caudal melanophore patch). Mutant melanophores are underpigmented and beginning to fragment. C, D) Dorsal image of caudal iridophore patch indicated by red arrow heads. Caudal patch and eye iridophores are the first to be affected in <i>integrity</i> mutants. E, F) Lateral image of 3dpf wildtype and <i>integrity</i> mutant larvae. We observe yellow coloration, indicative of xanthophores, in both wildtype and <i>integrity</i> mutant larvae (white arrows). G, H) Transmission electron microscopic images of 6dpf wildtype and <i>integrity</i> mutant larvae. Vertical sections were taken of dorsal stripe tissue and imaged at 3800X. <i>integrity</i> mutant melanosomes (compare arrowheads) are fewer in number and contain several presumed vacuoles as compared to wildtype. Epidermal plasma membranes are also fragmented (see white arrows) and internal organelle organization is disrupted. I-K) Representative images of fish used for quantification of iridophores (I) and melanophores (J, K). Trunk iridophores (in wildtype and mutant fish) are readily visible following epi-illumination using a fiber optic light source (see white arrows in I). Epinephrine promotes internalization of melanosomes, making individual melanophores easier to see and quantify (see red asterisks, which indicate the same region and is magnified in K). Distinct and continuous boundaries were used to designate a melanophore (e.g. the asterisk in K indicates four cells arranged in a U shape. L) Quantification of melanophores (dorsal and lateral stripes were included). Melanophores are significantly reduced as tested by two way ANOVA analysis with a Bonferonni multiple comparisons examining all genotypes and timepoints (p<0.001** or 0.0001***). M) Quantification of dorsal stripe iridophores in wildtype sibling and mutant larvae. Dorsal stripe iridophores are significantly reduced at all timepoints in mutant fish as tested by two way ANOVA analysis with a Bonferonni multiple comparisons examining all genotypes and timepoints (p<0.0001*** or 0.00001****). NOTE: 8−10 larvae per timepoint were counted; error bars are standard deviation.