FIG. 1.

Drosophila p53 and mnk/Chk2 are required for IR-induced apoptosis. Imaginal wing or eye disks were dissected from untreated (A, C, E, G, I, K, M, and O) or irradiated (B, D, F, H, J, L, N, and P) third instar larvae and stained with the vital dye acridine orange. IR-induced apoptosis was observed 4 h following irradiation in wild-type (B), mei-41 (D), mus304 (F), and grps (H) mutant larvae. No induction of apoptosis was observed in mnk (J) or p53 (L) mutant larvae. Damage-induced apoptosis was restored to mnk mutant disks by a transgene containing the mnk promoter and coding sequence (M and N). Damage-induced apoptosis was restored to the posterior (shown by brackets) of p53 mutant eye disks by a transgene driving expression of a p53 cDNA under control of a Glass-responsive promoter (described in Materials and Methods).