Structural organization of the Amy locus in seven strains of Drosophila melanogaster.

Restriction maps were made by Southern blot analysis of the Amy (alpha-amylase) region in 7 strains of D. melanogaster using endonucleases SalI, XhoI and EcoRI. These were compared to the map of lambda Dm65 which contains the cloned Amy region. Strains used produce either two amylase variants, a single variant, or no amylase, yet all 7 strains carry two Amy genes as inverted repeats at the Amy locus. This and the orientation of the repeats resembles the situation in lambda Dm65. Most restriction sites mapped are conserved but two strains contain a large insertion which differs in size and position between strains. A complex anomaly, probably an inversion, exists at the Amy locus in a null strain. Maps for our Amy1,3 strain and the lambda Dm65 clone are identical, the DNA of each having been derived from a Canton-S wild stock. Restriction and genetic maps of the Amy region were aligned and alleles assigned to the proximal and distal genes, Amy-p and Amy-d.