Abstract
We have used conditional wingless genotypes to dissect the role of this gene in late stages of wing disc development. One of these genotypes (wgIL/wg-lacZ) is simultaneously a reporter of wingless transcription and temperature-sensitive for wingless function, and has allowed us to define its pattern of transcription in the absence of wingless activity. The primordia of a subset of the bristles of the notum, which develop in or immediately adjacent to wingless-expressing cells, depend upon wingless activity. The time-course of this contribution and the effect on proneural gene expression together suggest that wingless may regulate the activity of products of the achaete-scute complex in proneural clusters. wingless activity is also required at the presumptive wing margin and is a necessary precondition for the change in proliferation pattern in this region. The involvement of wingless in transducing or mediating positional signals for spatial patterning in imaginal disc development is discussed.
