P{Switch}, a system for spatial and temporal control of gene expression inDrosophila melanogaster

We have developed a method for turning on and off the expression of transge nes within Drosophila in both time and space. Two different enhancer detect or elements carrying an RU486-inducible form of the yeast transcription fac tor GAL4 were constructed and used to generate enhancer detector lines. The se lines were screened for RU486-inducible reporter gene expression in the adult head. We identified lines that exhibit inducible expression in many c ell and tissue types, verifying that the elements respond to nearby enhance rs. No expression was detected in the absence of the ligand. The P{Switch1} element responded to genomic enhancers less efficiently than P{Switch2} bu t produced more specific patterns of expression. Two P{Switch} lines were u sed to ablate fat body tissue in adult females through the induced expressi on of diphtheria toxin. These females were sterile, which correlates with f at body loss, and they died prematurely.