Axon injury induces transcriptional changes in the Motoneuron cell body. (A) Schematic of the nerve crush assay. The segmental nerves within a third instar larva are crushed by pinching the ventral cuticle with forceps. (B) Injured segmental nerves 24 h after nerve crush. Synaptic vesicle precursors detected by staining for DVGLUT staining (green) accumulate at the proximal side of the crush site (arrow). (C) Cartoon of neuron cell bodies (blue dots) and segmental nerves (blue lines). Different crush sites (dashed red lines) injure a predictable number of motoneurons. Crush site 1 injures more cells than crush sites 2 and 3. (D) In uninjured animals, puc-lacZ expression is barely detectable. A nuclear localization signal on lacZ (green) localizes the reporter to the nucleus, and neuronal nuclei are detected by staining for the ElaV (red) marker. (E1–3) Injury induces puc-lacZ expression. 24 h (at 25°C) after injury at sites 1–3 induces expression of puc-lacZ in a defined subset of motoneurons as predicted by the anatomy cartooned in C. (F) Time course quantitation of puc-lacZ. The mean intensity of puc-lacZ is measured as described in Materials and methods for the dorsal midline neurons. 24 h after injury, puc-lacZ intensity is increased 3.5-fold compared with uninjured animals (n > 15). (G) Axon injury leads to a decrease of DVGLUT protein in motoneuron cell bodies. Error bars indicate mean ± SEM. Bars, 25 µm.