Figure 8. Joint over-expression of Dll and Rn is sufficient to cell-autonomously activate bab2 in haltere cells.

Joint over-expression of Dll and Rn proteins is sufficient to cell-autonomously activate bab2 in developing haltere pouch tissues. GFP expression (green), Bab2 immunostaining (blue) and RFP expression (red) alone, as well as the merged images, of the pouch tissues from haltere imaginal discs of LAE-RFP third-instar larvae carrying flip-out clones over-expressing either Dll (A–A′″), Rn (B–B″′) and Dll plus Rn (C–C″′), are shown. Flip-out clones (GFP+) were induced by a single heat shock in second or third instar larvae (see Materials and methods). Contrary to mosaic larvae carrying haltere pouch cells expressing either Dll or Rn alone, respectively, most of the clones (some are indicated by arrows) over-expressing both Dll and Rn cell-autonomously up-regulate bab2 and LAE-RFP expression, indicating a functional synergism between these transcription factors.