Fig. 7. REPO is necessary for the inhibition of neuronal differentiation by GCM. (A-D,I) The axonal scaffold was labeled using mAb BP102 (brown). (A-D) Glial cells were labeled by ß-galactosidase expression from the glial marker M84 (black). (E-H,J) All neurons in the CNS were labeled using the ELAV antibody. (A,E) Wild type. (B,F) Ectopic expression of GCM expression using the scabrous GAL4 driver. Ectopic expression of GCM in the repo mutant background (C,G), pointed mutant background (D,H) or ttk mutant background (I,J). Ectopic expression of GCM caused a reduction in the number of ELAV-positive neurons and axonal extension, as well as an increased number of cells that expressed the M84 marker (B,F). Removal of repo function resulted in a dramatic restoration of ELAV-positive cells and axonal development (C,G). The effect of removing pointed (D,H) or ttk (I,J) function was, respectively, undetectable or minor (compare with B,F). Note that the ttk mutant (I,J) is labeled for axons (I; mAB BP102) and neurons (J; ELAV); this animal did not carry the glial marker M84 (I,J). All embryos were stage 15. Anterior is upwards.