Mutations that induce the heat shock response of Drosophila

We have isolated a number of mutations in D. melanogaster that result in the constitutive expression of the heat shock response in a tissue-specific manner. These mutations induce alcohol dehydrogenase (ADH) when the ADH structural gene is fused to the promoter for the 70 kd heat shock protein (hsp70) gene. Flies carrying these mutations, the hsp70-Adh fusion, and a deletion in their endogenous Adh genes are ethanol tolerant and exhibit elevated ADH levels. Several of the tissue-specific mutations have also been shown to induce an hsp26-Adh fusion gene in trans. The mutation Act88F^KM75, a G→A transition in the indirect flight muscle-specific actin gene, also exhibits this phenotype. Comparisons with the Act88F^KM75 mutation suggest that the tissue-specific mutations induce the heat shock response by disrupting the physiology of the cells in which the variant gene product is expressed.