Fig. 4.
(A) A cheetah skin biopsy that includes a black-yellow boundary (also see fig. S6). (B) EDGE (13) determination of differential gene expression in black- as compared to yellow-colored areas of cheetah skin. Transcript frequency (observations per million sequence reads, mean of five samples) is plotted as a function of differential expression. The 74 genes with significant differential expression are shown in black or yellow (FDR < 0.05, see methods and tables S8 and S9); 7 additional pigmentation genes that are not differentially expressed are shown in pink. (C) Relative mRNA levels (mean ± SE) for the indicated genes as assessed by qRT-PCR from paired samples (n = 4) of dark and light neonatal tabby skin; *P < 0.05 (dark versus light, two-tailed t test). Dermal papilla expression of Edn3 mRNA (purple stain, white arrows) as detected by in situ hybridization, from a brown tabby individual. The left panel illustrates the expression of Edn3 mRNA in both pheomelanin- and eumelanin-containing follicles. (D) Phenotypes of 2-week-old mice of the indicated genotypes. Relative mRNA levels (mean ± SE) for the indicated genes from qRT-PCR of cDNA from control (n = 4) and transgenic (n = 4) mice are shown; *P < 0.05 (Ay versus Ay;Tg.K5-tTA;Tg.TRE-Edn3, two-tailed t test). Scale bars in (A), 40 and 200 μmin epidermis and whole-skin sections, respectively. In (C), 60 and 20 μmin left and right panels, respectively.