Figure 6.

Med12 and Cdk8 are both required for macrochaete specification/differentiation, including for normal sens expression in wing discs. (A–C) Representative nota from wild-type (A) or mosaic adults harboring large clones of Med12⁻ (B) or Cdk8⁻ (C) cells. Mitotic clones were generated in dorsal wing disc cells (see below), using ap-Gal4 together with a UAS-Flp construct and in a Minute background to confer a growth advantage to mutant cells. In the wild type, each hemi-notum normally displays a stereotyped pattern of large bristles, or macrochaetes (some are indicated by arrowheads). Note that apart from the loss of macrochaetes, large clones for Med12 can be accompanied by a thoracic cleft never seen for Cdk8. (D–F) Projections of confocal sections of entire L3 wing discs from wild-type (D–D′) or mosaic discs harboring large clones of Med12⁻ (E–E′) or Cdk8⁻ (F–F′) cells. Mutant cells are GFP⁻ (black). SOPs are revealed by anti-Sens antibody staining (in red). Boxes in (D–F) indicate the notum region, enlarged in the right panels (D′–F′). The ∼20 SOPs expressing sens in the thoracic region of late L3 wild-type discs (Nolo et al, 2000) contrast with the few remaining cells accumulating nuclear Sens protein in large Med12⁻ or Cdk8⁻ clones.