DNA map of mutations at the scute locus of Drosophila melanogaster

The achaete‐scute gene complex (AS‐C) of Drosophila melanogaster is involved in the differentiation of innervated elements in the adult (chaetes) and in the embryo (central nervous system). Genetically, the AS‐C is subdivided into four regions: achaete, scute α, lethal of scute, and scute β. Using a previously cloned fragment of scute DNA, we have now cloned 62 kb of wild‐type DNA from the scute region. No repetitive sequences have been detected in this stretch of DNA. Of 16 scute mutants with chromosomal rearrangements studied (inversions, deletions, and translocations), nine, included genetically in scute β, have breakpoints in the cloned region. The remaining rearrangements, which genetically correspond to scute α, map outside and to the left of the cloned region. Of nine scute ‘point mutants’ studied, eight have large DNA alterations within the cloned region. These alterations include insertions (five) and deletions (three). The DNA alterations found in both ‘point mutants’ and rearrangements are interspersed and scattered over 40 kb. The relationship between the sites of the DNA alterations and the mutant phenotypes are discussed.