Comparative analysis of binary expression systems for directed gene expression in transgenic insects.

Binary expression systems are of key interest to functional gene analysis by over- or misexpression. The application of such systems in diverse organisms would allow the study of many biological problems not addressable in model organisms. Here we report a set of constructs and an effective kinetic approach to quantitatively compare a series of diverse binary expression systems based on GAL4/UAS, LexA/(LL)(4) and tetracycline-controlled tTA/TRE. By the use of these constructs, we could show that in Drosophila melanogaster the yeast-derived GAL4/UAS systems are more effective in activating responder gene expression than the bacterial-derived LexA/(LL)(4) and tTA/TRE systems. The constructs are embedded in broad-range piggyBac-based transposon vectors and the transactivators are driven by the widely applicable 3xP3 promoter. These constructs should therefore be transferable to evaluate the functionality of binary expression systems in non-model insect species.