Molecular cloning of DNA complementary to Drosophila melanogaster alpha-amylase mRNA

Several lambda clones containing cDNAs from Drosophila melanogaster were identified in a lambda cDNA bank using two different approaches: (i) cross-species hybridization using a mouse amylase cDNA probe, and (ii) probing with a differential probe, generated from Drosophila RNA. An amylase cDNA fragment was used, in turn, for the isolation and characterization of amylase genomic clones. The size of the Drosophila amylase mRNA was estimated at 1650 b. This is comparable with the size of the murine amylase messenger that encodes a protein of similar molecular weight. In Drosophila larvae, amylase mRNA can account for as little as 0.01% of the poly(A)+ RNA under conditions of dietary glucose repression or greater than 1% of poly(A)+ RNA under derepressing dietary conditions.