Fig. 1. Loss of Puc function triggers apoptosis in embryonic epithelia. (A-D) Cuticles, ventral view, anterior upwards. (A) Wild-type; (B) puc^A251.1 M/Z; (C) puc^A251.1 maternal-only (arrowheads indicate denticle belts); (D) puc^A251.1 zygotic mutant. puc^A251.1 M/Z mutants secrete fragmented cuticle; this is suppressed by paternal Puc. (E-N) Embryos, anterior leftwards. Dorsal is upwards unless indicated otherwise. (E-J) Lateral views, TUNEL-label (green). Anti-phosphotyrosine (red) outlines cells. (E,F) Wild type stage 10 (E) and stage 13 (F). Arrowhead in F indicates leading edge cells. (G,H) Stage 10 (G) and stage 13 (H) presumptive puc^A251.1 M/Z mutants undergoing massive apoptosis. (I,J) Stage 10 (I) and stage 13 (J) presumptive puc^A251.1 maternal-only mutants, with fewer TUNEL-positive cells. (K,L) Wild type (K) and puc^A251.1 maternal mutants (L). Engrailed is in red. Arm-eGFP (green) indicates cell boundaries. (M,N) TUNEL-labeled (green) puc^A251.1 zygotic mutants. Mutants identified by ectopic JNK^REP activity (blue). Cell boundaries are indicated with DE-cad (red). (M) Ventrolateral view, stage 14. Arrowheads indicate TUNEL-positive cells. (N) Lateral view, stage 13. Arrowhead-leading edge cells with elevated JNK^REP activity. (O) UAS-rpr;en-Gal4;puc^A251.1/+, TUNEL-labeled (green). (P) JNK^REP activity from O (red). puc heterozygotes identified by JNK^REP activity at leading edge. Apoptosis is induced in segmental stripes, without induction of JNK^REP.