Fig. 3. The effect of ectopic accumulation of Pb on the expression of dac, Dll and exd. (A) There is a circular Dac (red) domain in wild-type leg discs (T2 is shown). (B) The pattern of accumulation of ß-galactosidase in the T3 leg disc of a dpp=>lacZ animal. Note the yellow nuclei expressing both ß-gal (green) and Dac (red). (C,D) dpp=>pb T2 and T1 leg discs showing a broken Dac (red) ring. The ring is interrupted by a stripe of Pb-expressing cells (green). (E) dpp=>lacZ is capable of driving lacZ (green) in Exd-expressing cells (red) of the T2 leg disc. (F) Little or no co-expression of Pb (green) and Exd (red) is seen in a T1 leg disc of dpp=>pb flies.(G) ß-gal (green) expression overlaps with that of Dll (red) in a dpp-lacZ T3 leg disc. Note multiple yellow nuclei expressing both Dll and ß-gal. (H) dpp=>pb showing Pb (green) in a stripe across a T3 leg disc stained with anti-Dll antibody (red). Although the normal expression pattern of Dll is altered, there is co-expression in many cells.