FIG. 6.

Additional distance dependence of permissive repressor-activator stoichiometries. The reporter gene structure is shown below and chimeric Gal4 activators used to drive expression from the reporter gene are indicated to the left of the embryos. (A, C, and E) Full-length Gal4 protein was expressed ubiquitously, while the minimal Gal4 activator and a Gal4-VP16 activator were expressed in ventral regions under the twist promoter. Giant (gt) represses all three activators when three Gal4 sites are present. (B, D, and F) Giant repression activity is absent when the three Gal4 sites are moved 37 nucleotides from the Giant sites, although still less than 100 bp from the Giant sites. Expression patterns were visualized in 2- to 4-h embryos by in situ hybridization with antisense lacZ probes.