Integration of the Hedgehog and Wingless Pathways patterns leg sensory organs. D. Bulanin, J. Wong, T. Orenic. Dept Biological Sciences, Univ Illinois, Chicago, Chicago, IL.

   A group of small mechanosensory bristles or microchaetes (mCs) in the Drosophila leg are organized into a series of longitudinal rows found at specific positions around the leg's circumference. Generation of this pattern requires the position-specific expression of the hairy (h) and achaete(ac) genes. In the pupal leg disc, a stripe of ac expression on either side of each h domain defines the primordia of the leg bristle rows. In the absence of h function, (ac) expression expands into the regions normally occupied by Hairy, resulting in disorganized bristle rows in the adult. h is expressed in four striped domains, one in each in the dorsal (D-h), ventral (V-h), anterior (A-h) and posterior (P-h) regions of the leg. We have found that regulation of two of these stripes (D-h and V-h) is directed by dorsal and ventral specific enhancers that integrate signals from multiple signaling pathways including the Hedgehog (Hh), Decapentaplegic (Dpp), Wingless (Wg) pathways. Here we examine the regulation of the D- and V-h stripes. We show that the D- and V-h stripes are activated by Hh, while Dpp and Wg are required to modulate the response to Hh.