| First Author | Ball ST | Year | 1989 |
| Journal | Mouse News Lett | Volume | 83 |
| Pages | 163-4 | Mgi Jnum | J:14236 |
| Mgi Id | MGI:62408 | Citation | Ball ST, et al. (1989) Koala, a dominant mutation. Mouse News Lett 83:163-4 |
| abstractText | Full text of MNL contribution: A male with very hairy ears arose in a specific locus experiment in which male C3H/HeH mice received a fractionated dose of (3+3) Gy X-rays, separated by 24 hours. Breeding tests showed the abnormality is inherited as a dominant and the mutation has been designated Koala, Koa. Heterozygotes have ears which are covered with a luxuriant growth of long hair on both the outer and inner surfaces, and also have a bushy muzzle. Homozygotes are slightly hairier than heterozygotes, have a flatter, broader head, and often have open eyes at birth. Provisional observations indicate that adult homozygotes weigh 20% less than heterozygotes. Crosses of Koa heterozygotes with wild type (either C3H/HeH or (C3H/HeH x 101/H)F1) have yielded 201 Koa +: 221 + +; and intercrosses have given 34 + +; 67 Koa +; 30 Koa Koa. Thus the mutant gene shows good penetrance and viability. Litter size is marginally reduced in intercross matings (7.4) compared to outcross matings (9.0). However, when homozygous Koa Koa are intercrossed, litter size is markedly reduced, (4.9), and no offspring have survived to weaning age, although offspring from such matings have been fostered successfully. Koa is on chromosome 15 linked to bt and Ca. From backcrosses of Ca +/+ Koa females to wild type males the offspring were Ca +, 14; + Koa, 34; Ca Koa, 0; + +, 0 (R.F. 0-7.7%; 95% confidence limits). There is a deficiency of Ca +, the reason for which is unknown. From backcrosses of uw bt +/uw bt + females to + + Koa/uw bt + males the offspring were + + Koa, 15; uw bt +, 14; uw + Koa, 8; + bt +, 9; + + +, 0; uw bt Koa, 0. This gives an R.F. of 37.0 + 7.1 between uw and bt; and uw and Koa. For bt and Koa the R.F. is between 0 and 7.4% (95% confidence limits). However, further data are needed. Another gene affecting pinna hair, hairy ears, Eh, is located close to bt on chromosome 15. Eh+ mice have a small pinna with a tuft of hair on the inner surface. Crossing over between Dom and Ca is suppressed by Eh (Lane and Lin, J. Hered., 75: 435, 1984). Work is in progress to establish if Eh and Koa are allelic, and also to find out if Koa suppresses recombination in the distal portion of chromosome 15. (Ball and Peters) |
