SIMPLE AND EFFICIENT GENERATION OF MARKED CLONES IN DROSOPHILA

Background: Cell lineage analysis and mosaic analysis of mutations are important techniques that are used to study the development of many o rganisms. Unfortunately, the methods employed for such analyses are us ually inefficient, technically demanding or labor intensive. In Drosop hila, the most common methodology used for the generation of mosaic an imals is mitotic recombination, which is induced by X-rays. Although t his technique is simple, it has the undesirable characteristics of a l ow efficiency and a high rate of cell death. Furthermore, although a l arge number of marker systems has been employed to detect mitotic reco mbinants, none allows easy identification of clones for all cell types . Results: A system is described here that allows a highly efficient g eneration of clones with the concomitant expression of an easily detec table cellular marker. This method can be applied to cell lineage and mosaic analysis in Drosophila The site-specific yeast FLP recombinase, under the control of a heat shock-inducible promoter, efficiently cat alyses mitotic recombination specifically at the site of a FLP recombi nation target (FRT). In this system, recombination fuses the alpha-tub ulin promoter to the lacZ gene, allowing transcription of the marker. Recombinant cells and their progeny can, therefore, be detected by sta ndard assays for beta-galactosidase. of particular importance is the f act that only the cells of interest stain, thus allowing their simple detection in any tissue. Conclusions: We demonstrate that, by intermol ecular recombination, we can use FLP recombinase to generate marked cl ones efficiently in embryonic, larval and adult tissues. This simple a nd efficient technique is well suited to cell-lineage analysis and can be easily extended to the generation and detection of mutant clones i n mosaic animals.