Dopa Oxidase Activity of Tyrosinase in Agouti Mutant Mice (a/a, AY/a, AwJ/AwJ: C57BL/6J)

The objectives of this research were two-fold. Initially, dopa oxidase (DO) activity in regenerated hairbulb preparations of 9-day black (a/a) and yellow (AY/a) mice was measured. At the outset of this study, the purpose was to determine the typical levels of DO activity occurring in black (a/a) and yellow (AY/a) mice and to use these data as a basis for. dopa oxidase studies involving the agouti mouse, Aw3/Aw3. The second objective was to determine the effects of the wild-type agouti genotype (Aw3/Aw3) on the regulation of dopa oxidase (DO) activity within regenerating hairbulb melanocytes. The agouti mouse presents a highly productive model for study because the hair which comprises it\u27s [sic] coat exhibits a banded pattern -- black tip, yellow subapical band, and black shaft. Upon plucking of telogen hairs, the agouti (Aw3/Aw3) mouse spends it\u27s [sic] first three days of regeneration preparing for pigment production, i.e. melanocytes become associated with the reorganizing hair follicle. On approximately the fourth day of regeneration, production of black pigment begins and continues through day 6.5 when a switch in pigment synthesis occurs. Phaeomelanin, or yellow pigment is produced from days 6.5-9.0. Then on day 9, the system switches back to black pigment, eumelanin, for the duration of the 21 day hair growth cycle