Site of gene action in the development of hair pigment in recessive yellow () mice

The Coat Colors of Mice

“…What it is that is unique about the follicular environment which turns on phaeomelanin synthesis in e/e pigment cells is not known, but perhaps it is related to the fact that melanocytes in hair follicles synthesize melanosomes at a much more rapid rate, for inclusion into the growing hair, than extra-follicular cells (Lamoreux and Mayer, 1975).…”

“…In the first of these studies (Lamoreux and Mayer, 1975) grafts composed of 9-day-old neural tube, including neural crest cells, and II-day-old neural crest-free embryonic skin were placed in the coelom of the chick and allowed to differentiate for 15 days. It was found that when a/a;e/e neural tube was grafted with a/a;E/E skin, the hairs of recovered grafts were pigmented yellow, whereas a/a;e/e skin produced black hairs when combined with a/a;E/E neural tube.…”

The eumelanin and pheomelanin contents in dorsal hairs of female recessive yellow mice are greater than in male

“…These results suggest that in the recessive yellow mice, the pheomelanin synthesis occurs in the epidermis and dermis in addition to hair follicles. Previous works have shown that the extension locus acts within the hair follicle melanocytes to determine whether pheomelanin or eumelanin is synthesized, namely melanocytes of Mc1r e /Mc1r e genotype produce pheomelanin only in a hair follicle environment [28][29][30][31]. We presented for the first time the evidence that Mc1r e /Mc1r e allele is involved in regulating the pheomelanin synthesis in the epidermis and dermis.…”

“…It is probable that melanocytes in the epidermis and dermis of Mc1r e /Mc1r e mice are capable of synthesizing pheomelanin even in the environment devoid of hair follicle structure. The detection method of eumelanin and pheomelanin in the earlier reports is visual inspection or paper chromatography of 0.1N NaOH extracts [28][29][30][31]. Their results show that pheomelanin is produced only by the hair follicular environment and the extrafollicular environment such as epidermis and dermis produces eumelanin only [28][29][30][31].…”

Genetics ofSex-linked yellowin the Syrian Hamster

“…Both Sly and Orange yield a uniformly pheomelanic pelage whose effects are epistatic to those of nonagouti, as is the case for Mc1r loss-of-function in mice (Silvers 1979), horses (Marklund et al 1996;Rieder et al 2001), and dogs (Newton et al 2000;Kerns et al 2004). Furthermore, both Sly and Orange interact with whitespotting mutations in a manner that suggests they are melanocyte autonomous, as is the case for mosaic Mc1r mutations in pigs (Kijas et al 2001) and mice (Lamoreux and Mayer 1975) and presumptive Mc1r mutations in guinea pigs and rabbits (Searle 1968). However, both Sly and Orange are genetically distinct from the Mc1r and possibly from each other.…”