A HIGH-RESOLUTION MAP OF THE BROWN (B, TYRP1) DELETION COMPLEX OF MOUSE CHROMOSOME-4

For over 40 years germ-cell mutagenesis experiments have generated man y new mutations at the brown (b or Tyrp1) locus on mouse Chromosome (C hr) 4. These mutations, many of which are deletions, were recovered by the specific-locus mutagenesis technique. Previous analysis of a pane l of brown deletions, generated at Oak Ridge, has enabled both a preli minary molecular and a functional map around the locus to be generated . We have used a panel of hybrid DNA from 25 Oak Ridge deletions, wher e the deleted chromosome was heterozygous with a Mus spretus chromosom e, to map polymorphic markers including microclones, microsatellites, and cloned DNA markers. We have generated a fine structure map, based on 25 new markers, of an 8.5-cM region surrounding the brown locus. Th is map will prove useful in future mapping studies of this region and in the isolation of the genes that lie within it.