title: Studies on the sal locus in Drosophila pseudoobscura. II. Modes of regulation of the sal banding pattern.
abstract: From a consideration of genetic and chromosomal alterations which affect the banding pattern of a specific salivary chromosome region, it is concluded that (1) a regulator locus, sal, is closely linked with the region in question but separated from it spatially by a few bands; (2) either mutation of the sal locus or transfer of the region to a heterochromatic region affects the banding pattern similarly; and (3) the change probably consists of a compaction of DNA and a concomitant inactivation of genetic loci.
mesh_terms: D000483:Alleles; D000818:Animals; D002869:Chromosome Aberrations; D002875:Chromosomes; D004330:Drosophila; D005809:Genes, Regulator; D005838:Genotype