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Fig. 3
Axonopathy is not followed by ‘dying back’ or Wallerian-like degeneration in aSyn-expressing neurons. (A,B) Time-lapse imaging of neurodegeneration. Cells were imaged every 20 minutes beginning 54 hours post-fertilization (hpf). Axons from at least 11 embryos from each group were transected; representative images from aSyn-expressing animals are shown. Time stamps in images are relative to the start of the imaging period. Axonal varicosities were observed (white arrowheads) several hours before cell death. White arrows point to morphological changes indicative of cell death. Inset represents cell body magnified 2×. Asterisk in A indicates separation of the axon from the cell body. Axonal fragmentation (blue arrowheads) usually did not occur before cell death, and was not stereotyped: it did not occur synchronously along the length of the axon, nor in a retrograde direction (yellow arrows point to distal portions of the axon that are still intact). (C,D) Representative images of wild-type (C) and aSyn-expressing (D) axons undergoing WD after transection with a two-photon laser. Axons were transected with a two-photon laser at 2 dpf, and embryos were imaged every 30 minutes for up to 12 hours. Red arrowhead points to site of transection. After injury, in both wild-type and aSyn-expressing axons, fragmentation was synchronous along the length of the transected axon (blue arrowheads). mpa, minutes post-axotomy. (E) There was no difference in the duration of the lag period between transection and fragmentation (WT: 129.1±10.0 minutes, n=11 axons from 11 animals; aSyn: 112.7±11.7 minutes; n=15 axons from 15 animals, P=0.3173). (F) The time between fragmentation and clearance of all axonal debris was not significantly different between the two groups (WT: 58.2±6.9 minutes; aSyn: 69.1±8.3 minutes; P=0.3213). Scale bars: 50 μm.