Ectopic expression inDrosophilahas been used extensively to examine the capabilities of a given gene in virtually any tissue. Three general approaches are described here, and the choice of which to use is determined by the needs of the particular experiment. Certain aspects of each approach can also be combined, providing powerful tools for the examination of gene function. Because ectopic expression does not involve a protocol, but rather generation of certain types of transgenic strains, this chapter focuses on a description of the approaches and in what circumstances each is likely to be useful.
