The genetics of a small autosomal region of Drosophila melanogaster containing the structural gene for alcohol dehydrogenase. VI. Induced revertants of scutoid.

Twenty-six induced revertants of Scutoid (Sco), a dominant mutation of Drosophila melanogaster, have been characterized genetically. Sco is an unusual mutation, involving two small reciprocal transpositions within the region 35A4 to 35C5 of chromosome arm 2L. One of these transpositions juxtaposes the noc and l(2)br28 loci. We suggested previously that the Sco phenotype results from the "fusion" of noc and l(2)br28. In support of this idea we now show that 23 of 26 revertants of Sco are noc-, indeed the majority are either chromosome aberrations broken between noc and l(2)br28 or deletions of these loci from the mutant chromosome. However, some revertants of Sco are rather more complex, and their properties suggest an interaction between the pu-noc and l(2)br28-l(2)br37 regions of chromosome arm 2L and also demonstrate the genetic complexity of the el-noc region.