Spastic Paraplegia Mutation N256S in the Neuronal Microtubule Motor KIF5A Disrupts Axonal Transport in a Drosophila HSP Model
Figure 4
Characterization of axonal swellings.
(A) Electron micrographs of segmental nerves of mid-L2 wild-type (D42>w1118) and mutant (D42>KhcN262S) larvae. Nerves of wild-type larvae contain mitochondria (green arrowhead) and microtubules (cyan arrowhead). Nerves of larvae expressing KhcN262S are frequently swollen. These swollen axons are filled with mitochondria (green arrowheads), prelysosomal vacuoles (red arrowheads), autophagosomes (dark blue arrowheads), and multivesicular bodies (purple arrowheads). Scale bars: 100 nm. (B) Box-plot of axon diameters in mid-L2 wild-type (D42>w1118) and mutant (D42>KhcN262S) larvae as determined by electron microscopy. The box displays median, upper, and lower quartile. The whiskers represent the 1st to 99th percentile. (C,D) Confocal images of immunofluorescent staining showing segmental nerves of mid-third-instar Drosophila larvae. Larvae were stained for the membrane marker anti-HRP as well as for the lysosome marker LAMP-GFP (C) and the autophagosome marker ATG8-mRFP (D). Axonal swellings are positive for autophagosomes and lysosomal organelles. Scale bars in C and D: 10 µm.