Fig. 5. Dac restricts bab expression in the leg. (A,A') Wild-type expression of Bab (purple in all panels) and Dac (green) in the leg disc. (B,B') bab expression is activated in a dac null clone (asterisk). The clone is marked by the absence of Myc (green). The wild-type twin spot (ts) of the clone possesses two copies of the myc transgene and therefore appears brighter green. Note that bab is non cell-autonomously activated in part of the twin spot near the clone (arrowhead). A portion of the endogenous bab ring of the first tarsal segment is indicated (t1). (D,D') bab expression is repressed by ectopic Dac (arrows) produced in the dpp pattern. The dpp pattern is dynamic (Masucci et al., 1990; Weigmann and Cohen, 1999), and Bab is not detected in cells that were exposed to high levels of Dac earlier in development and that continue to express moderate levels of Dac, probably due to autoregulation (arrowheads). (E,E') Bab expression expands proximally and its modulation between rings is greatly diminished in dac mutant leg discs. Dac appears to be expressed normally in bab null antennal (C) and leg (F) discs.
