Fig. 5. Repression of sal, omb and vg-QE following misexpression of modified/mutated forms of Brk in the posterior of wing discs using en-Gal4. The interface between posterior (p) and anterior (a) is marked by a dashed line (i.e. transgene expression was driven in cells to the right). (A) Wild-type Brk^3PF3 at 20°C completely represses sal (green) and omb (red). Brk^3PF3 is tagged with the HA epitope, shown in blue in part iii. (B) At lower temperatures (resulting in lower levels of transgene expression), wild-type Brk^3PF3 still completely represses sal (green) but some omb expression remains (arrow). (C,D) Brk^NLS (at 30°C) has no effect on the expression of sal or omb. (E) Higher magnification image focused on the large peripodial membrane cells, stained for HA, showing that expression of Brk^NLS is exclusively nuclear. (F) By contrast, Brk^NLSW (at 30°C) can repress sal completely and omb (arrow) almost completely. (G) Brk^Stop1NAC (at 25°C), which possesses only a CiM, completely represses sal and almost completely represses omb (arrow). (H) At 25°C, Brk^Stop1, which lacks both the GiM and CiM, represses sal and omb completely. (I) However, at 20°C, although the lower levels of Brk^Stop1 are sufficient to almost completely repress omb (there is some residual expression, arrow in ii), Sal is still expressed at high levels in the posterior (arrow in i). (J-L) Repression of vg-QE expression. (J) Brk^3PF3 drastically reduces the level and width of the vg-QE expression domain. (K) Brk^NLSW has no effect on vg-QE expression. (L) Brk^Stop1 almost completely represses vg-QE.