Fig. 4. Interactions between shi^ts and sema1a. Each row illustrates the results for a different UAS-construct, driven by c17. Each column indicates the results for a temperature shift at the indicated time. All specimens were dissected in the adult stage. (A) Specimens expressing UAS-sema1a alone. (A1,A2) Temperature shifts during synapse formation caused bendless-like phenotypes. (A3) Late temperature shifts (62.5% of pupal development) had no effect and were indistinguishable from (A4) controls that were not temperature shifted. (B) Specimens expressing only UAS-shi^ts. Very few defects were observed, usually all axons reached the target area and extended a lateral bend independent of the temperature shift. (C) UAS-sema1a and UAS-shi^ts were targeted to the presynaptic GFs. (C1) When temperature shifted at 37.5% of pupal development GFs exhibited a swollen terminal filled with vesicles in the target area (arrow). (C2) The left GF in this example at 50% of pupal development exhibits a swollen terminal and a retraction tail, the right GF is dramatically swollen and filled with membrane bound vesicles (arrow). (C3) Late temperature shifts cause some retraction and few swellings or vesicles. (C4) Control specimen that was not temperature shifted. Scale bar in A1: 20 µm.