Chick yellow: a new mutation on Chromosome 3 causing eye and coat color phenotypes.
Authors: Son Yong Karst, Patricia F. Ward-Bailey, Richard S. Smith, William D. Hohenboken*, Linda L. Washburn, Dave Bergstrom, Kenneth R. Johnson, Leah Rae Donahue and Muriel T. Davisson.
*retired professor Virginia Polytechnic Institute, College of Agriculture and Life Sciences, Department of Animal and Poultry Sciences. Dr. Hohenboken provided this mutation which he identified as a recessive coat color with a cosegregating eye mutation to us for further study.
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: chky
Mutation (allele) name: chick yellow
Gene symbol: chky
Strain of origin: Random bred swiss stock
Current strain name: STOCK chky/J
Stock #: 003148 (view JAX® Mice Data Sheet for additional information including Price and Supply Information)
Phenotype categories: Eye and coat color
Abstract
A new spontaneous recessive mutation has been identified, characterized and named chick yellow (chky). This mutation maps to Chromosome 3.
Origin and Description
The new chick yellow mutation arose in a breeding colony of inbred Swiss stock and was discovered by William D. Hohenboken at the Department of Animal and Poultry Sciences, Virginia Polytechnic Institute. It was then transfered to the Mouse Mutant Resource at The Jackson Laboratory.
Mice homozygous for the chick yellow mutation can be recognized when their first coat of hair comes in at about 10 days of age. This slightly yellowish coat color is visible only on an albino background (See photo). A recessive cataract phenotype also co-segregates with the chick yellow mutation (See photo).
Older animals in the chky colony may develop polydipsia but this is a strain characteristic of some Swiss types of mice and not likely due to the chky mutation.
Mice homozygous for the chky mutation live a normal lifespan and breed normally.
The colony is maintained by mating heterozygous (chky/+) mice with homozygous (chky/chky) mice.
Genetic Analysis
A chky homozygote mouse was mated with a wild type BALB/cByJ mouse. The normal F1 progeny from this mating were then intercrossed and generated 47 affected mice for linkage analysis.
Using standard mapping protocols, the recessive chick yellow mutation was mapped to Chromosome 3, between D3Mit 137 (NCBI 37 position 78.6 Mb) and D3Mit28 (NCBI 37 position 90.4 Mb). There is one recombinant with D3Mit137 and three recombinants with D3Mit28 (94 meioses tested).
Pathology
A routine pathological screen of one homozygous mouse at one month of age showed very early signs of cataracts (See photo). Two homozygous mice at three months of age showed early lens extrusion and early signs of cataracts (See photos).
Two homozygous mice, one at 7 months and one at 8 months of age showed retinal degeneration and cataracts, the 8 month old homozygous mouse also showed inflammation in the eye.
A complete necropsy of pelt pads and hair samples from two homozygous mice at 4 weeks of age showed normal looking skin and hair in both mice.
Two homozygous mice and two heterozygous mice at age 3 weeks were pathologically screened and tested for pelt pads. The results showed no lesions and the animal's skin looked normal.
Hearing assessments by auditory brainstem response testing (ABR) of two homozygous mice and two heterozygous mice at age 4 weeks showed normal hearing.
Acknowledgements
The authors thank Heping Yu for hearing assessment, Roderick Bronson and Coleen Kane for pathological screening, and Richard Smith for pathological eye examinations and photos.
