Underwhite-like: a new coat color mutation mapping near the Slc45a2 locus on Chromosome 15.
Richard M. Samples, Patricia F. Ward-Bailey, Leah Rae Donahue, Roderick T. Bronson, and Muriel T. Davisson
Source of Support: The research was supported by NIH/NCRR grant RR01183 to the Mouse Mutant Resources (M.T.Davisson,PI) and Cancer Center Core Grant CA34196.
Mutation (allele) symbol: uwl
Mutation (allele) name: underwhite-like
Gene symbol: uwl
Strain of origin: C57BL/6J
Current strain name: C57BL/6J-uwl/J
Stock #: 005962 (view JAX® Mice Data Sheet for additional information including Price and Supply Information)
Phenotype categories: coat color
Abstract
A spontaneous, recessive mutation that causes a very light coat color has been discovered and named underwhite-like (uwl). The phenotype and Chromosome 15 map location suggest that this new mutation may be a remutation to Slc45a2 uw, however a direct test for allelism was not performed because Slc45a2uw is only available as frozen embryos.
Origin and Description
The underwhite-like (uwl) mutation was discovered by Crystal Gewlas in a production colony of C57BL/6J mice (stock #000664) in AX-12 at the Jackson Laboratory on March 10, 2004. Mice homozygous for the uwl mutation on this nonagouti background are recognized by a very light skin color at birth, and the coat remains light throughout the animal's lifespan. This coat color is a very light cream color, not very different from albino but with more of a flesh tone (See Photos-ventral and dorsal). In mice homozygous for this new mutation, the lightness of the underwhite coat color is more extreme than that observed in original underwhite (Slc45a2uw) homozygotes. This dilution also lightens feet, ears and tail. Like mice homozygous for Slc45a2uw, this new uwl mutation has abnormal eye pigmentation. The eyes are unpigmented at birth, but become ruby colored at maturity.
Genetic Analysis
The underwhite-like mutation was first identified as a recessive mutation by crossing a C57BL/6J-uwl mutant to an inbred BALB/cJ mouse. In this cross no mutants were produced in the F1 generation, but mutants were produced in the F2 intercross generation. Using our standard mapping procedures an intercross with CAST/Ei was set up and generated 33 affected progeny that were used for linkage analysis. This new mutation maps on mouse Chromosome 15 between D15Mit13 (NCBIm34 position 3.2 Mb) and D15Mit265 (NCBIm34 position 12.7 Mb) and is non-recombinant with D15Mit175 (NCBIm34 position 9.0 Mb) and D15Mit10 (NCBIm34 position 10.4 Mb). The original underwhite mutation, (Slc45a2uw), also maps in this region (NCBIm34 position 10.8 Mb). Thus, the underwhite-like mutation is likely a remutation of Slc45a2uw; however a direct test for allelism between mice carrying the Slc45a2uw mutation and this new mutation was not performed because the Slc45a2uw mice are only available as cryopreserved embryos.
Pathology
A routine pathological screen of a mutant and a littermate control at 3 weeks of age showed no lesions.
Hearing as accessed by ABR of 3 mutants and 3 control littermates at 2.5 months of age was normal.
The eyes of 3 mutants and 3 littermate controls at 2.5 months of age were examined with an opthalamascope and determined to be normal.
Acknowledgements
The authors wish to thank Crystal Gewlas for the discovery of the mutant and Coleen Marden for her excellent technical assistance
