Fig. 3. Ectopic expression of Ttk69 in mature neurons disrupts axonal guidance. Late ectopic expression of Ttk69 in post-mitotic neurons, using the elav-Gal4 driver, does not repress the neural markers Elav (A), 22C10 (C) or Fasciclin II (E). It does, however, affect the behavior of mature neurons. (B-C) MAb 22C10 staining shows that the longitudinal tracts are disrupted (arrowheads) and the segmental and intersegmental nerves exhibit fasciculation and pathfinding abnormalities (arrows). (D-E) Anti-Fasciclin II (mAb 1D4) staining confirms that the longitudinal fascicles are disorganized after Ttk69 ectopic expression and that the intersegmental nerve is misrouted and often fails to exit the CNS, instead migrating back towards the midline (arrows). The elav-Gal4 driver also directs Ttk69 expression in neurons of the PNS. Strikingly, PNS organization was unaffected by this ectopic expression (data not shown).