ANALYSIS OF AN ENHANCER TRAP EXPRESSED IN REGENERATING DROSOPHILA IMAGINAL DISCS

In Drosophila, imaginal discs are the undifferentiated larval precurso rs of the pattern of epidermal and sensory neural cells in each adult segment. Although cell fates are already specified by late third insta r, disc fragments can either regenerate or duplicate after growth in c ulture. The outcome depends on signaling between cells across the heal ed wound and involves a redeployment of the expression patterns of sel ector genes and other disc pattern genes. We recently used the enhance r-trap method to screen for such genes that are expressed ectopically at the wound-heal site in imaginal discs undergoing regeneration. Here we report the cloning by plasmid rescue of transcribed sequences adja cent to one such enhancer-trap insertion. Using Northern analysis and in situ hybridization we show that one transcript is expressed in the embryo and in imaginal discs in a pattern similar to that of the enhan cer trap. We also, by imprecise excision of the enhancer-trap insertio n, generated a series of flanking deletions that were mapped using Sou thern analysis and complementation.