Figure 8.

Loss of Notch function is associated with increased levels of apoptosis in imaginal wing discs of the temperature-sensitive, conditional Notch mutant N^ts1. Acridine orange staining (A–C) or β-gal detection (D–I) of wing discs from third-instar larvae of genotypes N^ts1 (A–C), N^ts1; vg(quadrant enhancer)-lacZ (D–F), or N^ts1; ac-lacZ (G–I) at either the permissive temperature (A, D, and G), three days after shifting to the nonpermissive temperature (B, E, and H), or five days after the shift (C, F, and I). Loss of Notch signaling in N^ts1wing discs can be visualized by the diminished vg(quadrant enhancer)-lacZ expression in the wing pouch (D–F) and the expansion of ac-lacZ expression (G–I, arrowheads). Correlated with these changes, increased levels of apoptosis are first detected mostly in the notum region where the expansion of ac-lacZ expression is first seen (B and H). After the five-day temperature shift, apoptotic cells are mainly limited to the wing pouch zone where vg(quadrant enhancer)-lacZ expression is significantly reduced (C and F). Anterior at left.