IDENTIFICATION OF FAT-CELL ENHANCER ACTIVITY IN DROSOPHILA-MELANOGASTER USING P-ELEMENT ENHANCER TRAPS

To identify genes important in fat-cell metabolism and development, we have screened Drosophila stocks carrying an engineered transposable e lement that can reveal the presence of nearby enhancer elements. We ha ve identified those ''enhancer-trap lines'' that contain transposable P elements integrated near fat-cell specific enhancer elements. We ant icipate that the genes associated with these enhancers will provide in formation concerning fat-cell function and serve as target genes for s tudying fat-cell specific gene expression. Furthermore, the identifica tion of enhancer-trap lines active in the developing fat cell should p rovide an entry point into the molecular and genetic analysis of early fat-cell development. Analysis of two lines has revealed that the tra nscription factors svp, a steroid-hormone receptor, and Kr, a zinc-fin ger protein, are present in the fat body; these factors are likely to be involved in fat-cell gene expression. In two other lines, beta-gala ctosidase was detected in a subset of adepithelial cells that may be t he precursors to the adult far cell. And finally, in a single line tra nsgene activity is present in the progenitor cells of the embryonic fa t body. The genes associated with these enhancer-trap lines may be inv olved in fat-cell development.