Fig. 5. Abd-B is critical for the survival of posterior dMP2 neurons. In wild-type embryos, all dMP2 neurons are present at stage 16 as visualized by dMP2-GAL4/+; UAS-nls-myc-EGFP (A), while only posterior ones survive at a later stage (C). In Abd-Bm mutants (dMP2-GAL4, Abd-B^M5/Abd-B^M2; UAS-nls-myc-EGFP), no Abd-Bm protein is detected and Abd-Br expression is confined to the posterior tip of the VNC (B). Posterior dMP2 and MP1 neurons are still normally generated and always express Odd (F, arrowhead and asterisk, respectively). However, at stage 17 they also undergo apoptosis and no dMP2 neurons survive in late Abd-Bm mutant embryos (D). In A to D, n>7 VNCs. At the onset of their degeneration, Abd-Bm is always absent from posterior dMP2 neurons (E, arrowhead). As a result, 55% of posterior dMP2 neurons express rpr^GAL4 in Abd-Bm mutants (G, arrowheads; rpr^GAL4, Abd-B^M5/Abd-B^M2; UAS-nls-myc-EGFP; n>90 cells). (H-J) Cell-autonomous, postmitotic rescue of posterior dMP2 neurons in Abd-Bm mutants with dMP2-GAL4/UAS-Abd-Bm (in red; genotype is UAS-Abd-Bm; dMP2-GAL4, Abd-B^M5/Abd-B^M2). At stage 16, all posterior dMP2 neurons express Abd-B (H) and Odd (J) while no other cells express Abd-B in segments A6-A8. (I) As a result, posterior dMP2 death is rescued in late embryos (76%, n=10 VNCs).