Neuronal Overexpression of Spastin Causes Midline Convergence of Embryonic CNS Axons

<div><p>(A) Anti-Fasciclin II (mAb 1D4) staining of filleted late stage 16 control embryos reveals three longitudinal axon bundles (arrow) on each side of the midline. Anterior is up.</p> <p>(B) In <i>sca-GAL4/+; T32/+</i> embryos raised at room temperature, overexpression of Spastin in neurons causes the ladder to constrict toward the midline (e.g., arrow).</p> <p>(C) Increased Spastin expression at 29 °C causes collapse of the CNS onto the midline (arrow). Longitudinal axon tracts are thin or absent (arrowhead).</p> <p>(D) A phenotype similar to that in (C) is produced by <i>sca-GAL4</i>-driven expression of the <i>UAS-spastin</i> cDNA insertion at 23 °C. Arrow and arrowhead indicate same as in (C).</p>