Figure 4.

Sens and Ac synergize in vivo and in vitro. (A) Thorax of a y w fly. (B) Thorax of an ac^Hw-1 mutant. ac^Hw-1 causes ectopic expression of Ac, leading to an occasional additional macrochaetae. (C) Thorax of a fly expressing Sens using a relatively weak UAS-sens transgene under the control of sca-GAL4 driver. A few extra bristles are observed in clusters. (D) Same as in C, but in an ac^Hw-1 mutant background. Note the presence of numerous extra bristles, often in clusters. (E) Quantification of the number of macrochaetae in hemi-nota of flies shown in A-D. (F) Transcription assay in S2 cells using an enhancer/promoter fragment of the ac gene to drive luciferase (luc). H depicts Hairy/E(spl)-binding site. Note the 50-fold synergism between Sens and Ac/Da. (G-J) Wings of flies overexpressing Sens (G), E(spl)m8 (H), and both Sens and E(spl)m8 (I,J) in the wing pouch using C5-GAL4. (K) The transcriptional synergy obtained with Sens/Ac/Da (black) and Sens-del/Ac/Da (red) were normalized to 100%. Note that the ability of E(spl)m8 to antagonize the Sens-del synergy is significantly decreased compared with the wild-type Sens synergy.