Abstract
A chimeric gene, consisting of 428 bp of the promoter sequences of the alpha-amylase gene of Drosophila melanogaster, fused to the transcribed region of the alcohol dehydrogenase (Adh) gene, was introduced into the genome of an Adhnull stock of Drosophila via P element mediated transformation. DNA analysis (Southern blotting) of three transformant strains confirmed the insertion of either one or two copies of the chimeric gene per strain. A histochemical study of ADH enzyme activity in dissected tissues of the transgenic larvae revealed that the chimeric Amy-Adh gene was expressed only in the posterior larval midgut and that this expression was repressed by dietary glucose, thus representing an expression pattern characteristic of the Amy gene. This indicates that the Amy upstream promoter sequences contain signals mediating both tissue specificity and glucose repression of the Adh structural gene in the transgenic larvae. The level of ADH activity expressed in transgenic flies was relatively low. This was paralleled by a low level of Adh mRNA, indicating a reduction in the transcriptional rate of the chimeric gene.
