FLP/FRT Induction of Mitotic Recombination in Drosophila Germline

The FLP/FRT system is a site-directed recombination technology based on the targeting of a recombination enzyme (flipase - FLP) to specific DNA regions designated as flipase recognition target (FRT) sites. Initially identified in Saccharomyces cerevisiae, the yeast FLP-enzyme and its FRT recombination targets were successfully transferred into each major chromosome arm in Drosophila (Golic and Lindquist, 1989). This offers the ability to mediate mitotic recombination in vivo during development in a controlled manner [revised in Theodosiou and Xu (1998)]. The controlled induction of the mitotic recombination events is usually performed by expressing the FLP under the control of the heat-shock (hs) promoter. This allows the expression of high FLP levels at specific developmental time windows. Strains carrying these genetically marked FLP/FRT chromosomes have greatly enhanced our ability to study gene function in both germline and somatic Drosophila tissues. Here we describe two different protocols: One to induce and identify homozygous mutant clones in ovaries and the other to generate female germline mutants for the analysis of maternal effects on embryogenesis.