Recessive spotting-like(rslk): a new spontaneous mutation on mouse Chromosome 5

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 Resource (M.T.Davisson, PI) and Cancer Center Core Grant CA34196.

Mutation (allele) symbol: rslk

Mutation (allele) name: recessive spotting-like

Gene symbol: rslk

Strain of origin: B6.SJL-PtprcaPep3b/BoyJ

Current strain name: B6(SJL) Ptprca Pep3b-rslk/J

Stock #: 005574 (view JAX® Mice Data Sheet for additional information including Price and Supply Information) NOTE: after Jan 19, 2007 available as DNA only from the Jackson Laboratory DNA Resource.

Phenotype categories:color

Abstract

A new spontaneous recessive mutation that causes a diluted coat  and a variable sized white blaze on the ventrum in homozygotes has been identified and named recessive spotting-like (rslk).This mutation is strain background dependant, whereby on some strain backgrounds the subtle spotting in heterozygotes is not observed. On this background strain the subtle belly spotting has been observed in some heterozygotes. The mutation maps to Chromosome 5 in the same position as the previously described mutation recessive spotting (rs)(MGD 2005). A direct test for allelism was not performed because rs mice are available as cryopreserved embryos only.

Origin and Description

Mice carrying the recessive spotting-like mutation were discovered by Andy Carlson in a production colony of B6.SJLPtprca Pep3b/BoyJ (Stock#002014) in MP13 at the Jackson Laboratory on September 8, 2001. Mice homozygous for this spontaneous, recessive mutation are recognizable by a diluted dark gray coat color and a variable sized white blaze on the ventrum (See Photo). Mice carrying the rslk mutation live a normal lifespan and both sexes breed well.

Genetic Analysis

Using our standard mapping procedures , a homozygous female B6(SJL) Ptprca Pep3b-rslk/J mouse was mated to a Cast/Ei/J male. Heterozygous F1 mice from this mating were then intercrossed and produced 37 F2s that were used for linkage analysis. This new mutation was mapped to Chromosome 5 between D5Mit135 (42cM) and D5Mit114 (44cM) and is non-recombinant with D5Mit235 (42 cM). The previously described recessive spotting mutation (rs) is also positioned at 42 cM. Of the 37 mutant F2s produced in the linkage cross 7 animals were scored as heterozygotes (See Photo) which is not surprising, as heterozygous mice carrying the original rs mutation may show subtle spotting.

Pathology

A pathological screen  of one mutant and one control at 8weeks of age showed no lesions.

Discussion

Based on the phenotype and the chromosomal position of the recessive spotting-like (rslk) mutation it is likely a remutation to recessive spotting (rs), however a direct test for allelism was not performed due to the unavailability of the rs mice.

Acknowledgements

The authors wish to thank Andy Carlson for the discovery of the mutant and Coleen Marden for her excellent technical assistance.

References

Mouse Genome Database (MGD) Mouse Genome Informatics Project, The Jackson Laboratory, Bar, Harbor, Maine. World Wide Web (URL: http://www.informatics.jax.org).