Knockdown of <i>Tyr in vivo</i> is not sufficient to induce significant melanin loss in the black mouse coat.

Dorsal hairs of non-agouti double transgenic and control mice on continuous doxycycline treatment were shaved and processed for chemical analysis of eumelanin and of pheomelanin based upon their specific degradation products, pyrrole-2,3,5-tricarboxylic acid (PCTA) and 4-amino-3-hydroxyphenylalanine (4-AHP), respectively. Approximately 20 mg of hair was homogenized with a Ten Broeck homogenizer at a concentration of 10 mg/mL and 100 μL aliquots were subjected to Soluene-350 solubilization to quantify total melanin, alkaline hydrogen peroxide oxidation to quantify total PCTA, and hydroiodic acid hydrolysis to quantify 4-AHP in duplicate. The data corresponds to the averages of five control mice (Tyr-shRNA only or rtTA driver only) and five Tyr-knockdown mice, and the value is the mean of duplicate measurements. Each hair sample was derived from a single mouse. Within group summary statistics represent the arithmetic mean and (standard deviation). Differences in means between rtTA3/Tyr-shRNA and control were tested using a two-sample t-test with no assumption of equal variances between groups. P-values correspond to a test of the null hypothesis of no difference in true means between the groups. Percent of control is presented for descriptive purposes and represents the relative mean for rtTA3/Tyr-shRNA when compared to control. See also S2 Fig. Knockdown of Tyr in vivo is not sufficient to induce significant melanin loss in the black mouse coat.