Figure 5.

Antp represses D4/lacZ in the proximal Dll+Hth ring of the second leg imaginal disc. (A) A second leg disc stained for Hth and Dll. Hth is expressed in a broad proximal domain, whereas Dll is expressed in a 5-7 cell wide proximal ring whose distal border coincides with the distal limit of Hth. Dll is also expressed in the central (distal) region of the disc, which is only partly in the plane of focus. Cx=coxa, Tr=trochanter, Fe=femur, Ti=tibia, and Ta=tarsus. (B) An adult second leg. Abbreviations as in (A). (C) A second leg disc stained for Dll and Antp. Antp is expressed in a broad proximal region, and is upregulated within the Dll ring. (D) Antp^- clones, marked by the loss of GFP, in a second leg disc. D4/lacZ is activated in Antp^- clones where they overlap the Hth + Dll ring (arrowhead). Antp^- clones that do not overlap the ring (arrows) show no activation of D4/lacZ, have interdigitated borders, and appear to develop normally. (E) Antp^- clones in the coxa and trochanter marked by yellow bristles (arrows) produce normal cuticular structures. (F) An Antp^- clone in the femur marked by yellow bristles produces normal structures. (G) An Antp^- clone (outlined in white) in the proximal ring has no effect on expression of Hth or Dll. (H) All cells expressing D4/lacZ within an Antp^- leg clone also express both Hth and Dll. Clones are not marked in this disc to allow direct comparison of Dll, Hth, and D4/lacZ. (I) A partially rounded up Antp^- clone showing expression of Ss within part (white outline) of the D4/lacZ-expressing region. (J) An Antp^- clone marked by the absence of GFP in a second leg disc showing activation of D4/lacZ and ectopic expression of Hth. Note that D4/lacZ and Hth are expressed in a rounded-up portion of the clone (arrowheads), which is presumably transformed to antenna, whereas the remainder of the clone is interdigitated. Although not visible in this focal plane, the region of the clone expressing D4/lacZ and Hth retains a connection to the proximal Hth + Dll ring.