FLP-mediated DNA mobilization to specific target sites in Drosophila chromosomes

The ability to place a series of gene constructs at a specific site in the genome opens new possibilities for the experimental examination of gene expression and chromosomal position effects. We report that the FLP-FRT site-specific recombination system of the yeast 2μ plasmid can be used to integrate DNA at a chromosomal FRT target site in Drosophila. The technique we used was to first integrate an FRT-flanked gene by standard P element-mediated transformation. FLP was then used to excise the FRT-flanked donor DNA and screen for FLP-mediated re-integration at an FRT target at a different chromosome location. Such events were recovered from up to 5% of the crosses used to screen for mobilization and are easily detectable by altered linkage of a white reporter gene or by the generation of a white⁺ gene upon integration.