cut is necessary and sufficient for NB death. (A-C) Knockdown of cut in the nervous system (B), or cut loss in mutant embryos (C), results in ectopic abdominal NB survival, compared with control (A), as detected by Dpn staining in stage 17 embryos. Yellow bars mark the abdominal hemisegments. (D) Quantification of Dpn+ NBs in five abdominal hemisegments in late stage 17 embryos (n=4-6). (E-G) cut overexpression (F) results in premature NB loss by apoptosis compared with control (yw; E). Fewer NBs can be seen in each hemisegment, particularly in the anterior of each hemisegment (red bar) at stage 14. This NB loss is blocked by the broad-spectrum caspase inhibitor p35 (G). Yellow dashed lines mark parasegment boundaries. (H) Quantification of premature NB loss in three abdominal hemisegments of stage 14 embryos (n=3 for each genotype). Overexpression of cut results in premature NB death, which is partially inhibited by p35. Premature NB loss resulting from cut overexpression is not rescued by abd-A knockdown. For all embryos anterior is to the top. Data are mean±s.d. *P<0.05 versus control; unpaired t-test. Scale bars: 20 μm.