P-element-mediated enhancer detection allows rapid identification of developmentally regulated genes and cell specific markers in Drosophila.

We have employed a new technique in Drosophila that allows in vivo detection of genomic regulatory elements using a beta-galactosidase reporter gene. A translational fusion of the reporter gene to the P-transposase gene, which is encoded by the P-transposon of Drosophila, places the expression of beta-galactosidase under the control of the weak P-transposase promoter. Flies carrying single insertions of this P-element construct at different locations in the Drosophila genome frequently stain for beta-galactosidase activity in a temporally and spatially restricted fashion in embryos, larvae and adult ovaries, reflecting the influence of nearby genomic regulatory elements on the P-transposase promoter. This technique is a powerful tool as it can be used to produce very many different cell markers and to isolate developmentally regulated genes in Drosophila. We discuss the implications of our results and the applications of the technique to further the study of Drosophila development.