title: Effects of the white allele of the mi locus on coat pigmentation in chimeric mice.
abstract: To investigate the cellular action of the Miwh allele in the mouse with regard to its effects upon coat color patterns, we generated a series of aggregation chimeras, using embryos that differ in their mi locus genotype. We have obtained 11 chimeras Miwh/+C/C<==>+/+ c/c and 8 chimeras +/+ C/C<==>+/+ c/c. Chimerism was determined by coat and retinal pigment epithelium mosaicism and by the electrophoretic analysis of GPI-1 isoenzymes. In Miwh/+ C/C<==>+/+ c/c mice white coat color prevailed due to the higher percentage of unpigmented areas and the higher percentage of unpigmented hairs in pigmented areas. Our data indicate that a single Miwh gene dose decreases the melanoblast proliferative activity, causing the lightening of coat pigmentation. In Miwh/+ C/C<==>+/+ c/c mice a few pigmented hairs were often detected on the belly where Miwh/+ mice always had a white spot. This suggests that in the chimeras the presence of some non-Miwh cells in the skin of the belly allows pigment cells to develop. Using embryos of two substrains of Miwh/Miwh mice that differ in their Gpi-1 locus genotype we have produced 8 Miwh/+<==>Miwh/Miwh chimeras. In all these chimeras coat color patterns resembled those of Miwh/+ heterozygotes despite the higher percentage of the Miwh/Miwh component in three chimeras. Mosaic hairs were absent in the chimeras. This shows that the chimeras have only one Miwh/+ melanoblast population which actively proliferates and colonizes almost all hair follicles. Thus the Miwh/Miwh dermis and epidermis do not suppress proliferation and differentiation of the Miwh/+ melanoblasts except the certain area on the belly.
authors.affiliation: Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow.
authors.forename: B V
authors.initials: BV
authors.lastname: Konyukhov
authors.forename: B N
authors.initials: BN
authors.lastname: Kindyakov
authors.forename: N A
authors.initials: NA
authors.lastname: Malinina
mesh_terms: D000483:Alleles; D000818:Animals; D002678:Chimera / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D005260:Female; D005838:Genotype; D005956:Glucose-6-Phosphate Isomerase / Q000032:analysis; D006200:Hair Color / Q000235:genetics*; D008297:Male; D008544:Melanocytes / Q000166:cytology; D051379:Mice; D008815:Mice, Inbred Strains; D051739:Microphthalmia-Associated Transcription Factor; D010857:Pigment Epithelium of Eye; D014157:Transcription Factors
chemical_list: D004268:DNA-Binding Proteins; D051739:Microphthalmia-Associated Transcription Factor; C497235:Mitf protein, mouse; D014157:Transcription Factors; D005956:Glucose-6-Phosphate Isomerase