Fig. 2. Expression of Ag-ASH and Ag-pnr in Drosophila. (A) A wild-type notum. (B) The GAL4 line pnr^MD237 was used to drive Ag-ASH expression in the medial notum of Drosophila; this leads to the segregation of many ectopic bristles in the medial domain of the notum. Note that the slight midline cleft is a mutant phenotype associated with the pnr^MD237 insert. (C) The results of ectopic expression of Ag-pnr in the lateral notum with the driver C765. Note the presence of additional, large, (dorso-central) bristles on the lateral posterior scutum. (D) The notum of a fly in which early ubiquitous expression of Ag-pnr over the entire dorsal notum was driven by Gal4ap. Elements of the lateral pattern are absent, but the medial pattern is formed normally apart from some extra bristles along the lateral margin.