Figure 3.

Characterization of the Koa inversion mutation. (A) The Koa phenotype is due to a 51.5 Mb inversion on mouse chromosome 15. The proximal Koa inversion breakpoint was mapped between Trps1 and Eif3s3, 791 kb upstream of Trps1. The distal inversion breakpoint falls between Hoxc4 and Smug1. (B) Southern blot analysis using probe Koa-P14 identified a 2.1 kb band of altered size in a Koa/+ mouse that was not present in its +/+ littermate. (C) A bar graph depicting quantitative real time-polymerase chain reaction values for Trps1 expression in the muzzle skin (MS) and dorsal skin (DS) at E14.0, E16.5, E18.5 and P3 in wild-type, Koa/+ and Koa/Koa mice. Data are represented as mean ± SD. Trps1 expression was significantly reduced in both Koa/+ and Koa/Koa MS at all timepoints examined, with lower expression in the homozygous mutants than in heterozygous mice. Trps1 expression was significantly reduced in both Koa/+ and Koa/Koa samples at E14.0, E16.5 and P3 in the DS. Trps1 expression differences were less extreme in the MS and DS at E18.5.