Figure 3. Overexpression of Insb led to Notch inhibition.

(A–C) micrographs showing the bristle pattern on the dorsal thorax of control (A), insb^m (synthetic mutation resulting from combining the insb ^Δ1 deficiency with the insb^mCherry BAC; B) and pnr>Insb-GFP (C) flies. Loss of insb had no significant effect on the bristle pattern whereas ectopic expression led to bristle loss (associated with a transformation of external cells into internal cells) and bristle tufts (due to an excess of SOPs). (D–G”) The bristle loss phenotype of pnr>Insb-GFP flies was associated with i) an increased density of sensory organs (Cut, green; Elav, red) in the dorso-central region (bracket) of the notum in 22 hrs APF pupae (compare pnr>Insb-GFP pupae in F–F” with wild-type (wt) pupae in D–D”) and ii) a transformation of sense organ cells into neurons (Elav, red). Both increased density of sensory organs and transformation of sensory cells into neurons are indicative of a strong loss of Notch signalling (see magnifications in E–E” and G–G”). The expression pattern of pnr-Gal4 is indicated with dashed lines in D” and F”. Scale bars are 100 µm. (D–D” and F–F”) and 5 µm. (E–E” and G–G”).