Fig. 5. Bar represses the expression of ato at the level of transcription. (A) The expression of 3'F:5.8 ato-lacZ in eye-antennal disc of wild-type fly. ß-gal is detected in a few columns posterior to the furrow where endogenous Ato is normally absent. This is probably due to the perdurance of ß-gal protein, because ß-gal mRNA expression of 3'F:5.8 ato-lacZ line faithfully mimics the expression pattern of endogenous ato mRNA (Sun et al., 1998). (B-D) Bar represses ato expression at the transcription level through 3'-regulatory element of ato. Bar mutant cells were marked by the loss of GFP staining (B,C) and showed dramatically increased expression of ß-gal within the clone (D, arrows). (E) The expression of 5'F:9.3 ato-lacZ in the eye disc of wild-type fly. (F-H) Bar mutant cells showed a dramatically elevated expression of 5'F:9.3 ato-lacZ within the clone. Bar mutant cells were marked by the loss of GFP staining (F,G). (I) The expression of 5'F:9.3 ato-lacZ in eye-antennal disc of wild-type fly. Note normal ato-lacZ expression in the antennal disc. (J-L) Misexpressed BarH1 by dpp-Gal4 strongly downregulates the expression of 5'F:9.3 ato-lacZ (J,K) and of 5'F:7.2 ato-lacZ (L). Ato expression in the ventral region of the antennal disc was strongly downregulated (J-L, arrows). (M-P) Bar represses ato expression at the transcription level through 5'-regulatory element of ato. Note that many cells within Bar loss-of-function clones were lacZ-positive but Sens negative (N,O, arrows).

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