Htt depletion in type Is synaptic boutons attenuates DCV retrograde flux. A. Contrast-enhanced time-lapse images of type Is boutons expressing AnfGFP show a DCV (arrows) traveling by retrograde transport between adjacent boutons. The time interval between frames is 0.5 seconds. Scale bar 1 μm. B. Htt knockout decreases retrograde DCV flux in proximal boutons expressing AnfGFP. Control (Con), n = 21; Htt KO, n = 20. **p < 0.01, Unpaired t-test. C. Retrograde flux is not affected at the most distal boutons in Htt knockout larvae expressing AnfGFP. Con, n = 6; Htt KO, n = 14. Unpaired t-test shows that there is no significant (ns) change.