The mouse ruby‐eye 2 d ( ru2 d / H ps5 ru2‐d ) allele inhibits eumelanin but not pheomelanin synthesis

Summary The novel mutation named ru2 d / H ps5 ru2‐d , characterized by light‐colored coats and ruby‐eyes, prohibits differentiation of melanocytes by inhibiting tyrosinase ( T yr) activity, expression of T yr, T yr‐related protein 1 ( T yrp1), T yrp2, and Kit. However, it is not known whether the ru2 d allele affects pheomelanin synthesis in recessive yellow ( e/ M c1r e ) or in pheomelanic stage in agouti ( A ) mice. In this study, effects of the ru2 d allele on pheomelanin synthesis were investigated by chemical analysis of melanin present in dorsal hairs of 5‐week‐old mice from F 2 generation between C 57 BL /10 JH ir ( B 10)‐co‐isogenic ruby‐eye 2 d and B 10‐congenic recessive yellow or agouti. Eumelanin content was decreased in ruby‐eye 2 d and ruby‐eye 2 d agouti mice, whereas pheomelanin content in ruby‐eye 2 d recessive yellow and ruby‐eye 2 d agouti mice did not differ from the corresponding R u2 d /‐ mice, suggesting that the ru2 d allele inhibits eumelanin but not pheomelanin synthesis.