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Neurofilaments are flexible polymers that often fold and unfold, but they move in a fully extended configuration †
Article first published online: 12 JUN 2012
Copyright © 2012 Wiley Periodicals, Inc.
Special Issue: Emerging Concepts in Neuronal Cytoskeleton
Volume 69, Issue 7, pages 535–544, July 2012
How to Cite
Taylor, N. J., Wang, L. and Brown, A. (2012), Neurofilaments are flexible polymers that often fold and unfold, but they move in a fully extended configuration . Cytoskeleton, 69: 535–544. doi: 10.1002/cm.21039
- Issue published online: 6 JUL 2012
- Article first published online: 12 JUN 2012
- Manuscript Accepted: 9 MAY 2012
- Manuscript Revised: 8 MAY 2012
- Manuscript Received: 6 APR 2012
- NSF. Grant Number: IOS-0818653
- NIH. Grant Numbers: R01-NS38526, P30-NS045758
Additional Supporting Information may be found in the online version of this article.
|CM_21039_sm_SuppMovie1.mov||1442K||Note: these movies are best viewed in QuickTime 7. In QuickTime 10, some movies are automatically resized to accommodate the playback control bar. Movie 1. A neurofilament trapped at a branch point. Note the contortions of the filament, which illustrate the remarkable flexibility of these polymers. At one point, the filament folds back on itself several times giving rise to a transient pretzel-shaped configuration. At a later point, one end of the filament folds back on itself to form a hairpin loop. See Figure 2. Proximal is bottom, distal is top. Time compression=30:1.|
|CM_21039_sm_SuppMovie2.mov||3224K||Movie 2. A folding neurofilament. A pausing filament folds and unfolds three times: first internally, second at its distal end (including what appears to be a hairpin fold), and third internally again. See Figure 3. Proximal is left, distal is right. Time compression=30:1.|
|CM_21039_sm_SuppMovie3.mov||31134K||Movie 3. A moving neurofilament. A long filament moves intermittently across the field of view. Note the uniformity of the fluorescence along the length of this filament, which indicates that it is moving in a fully extended configuration. Proximal is left, distal is right. Time compression=30:1.|
|CM_21039_sm_SuppMovie4.mov||36686K||Movie 4. Moving and folding filaments (example 1). This is a busy movie showing two axons that cross each other. The axon that runs from bottom left to top right contains many moving and folding filaments. Several of these filaments exhibit complex and dynamic folding behaviors, including one that forms a transient hairpin loop at its proximal end, and another that forms a transient internal loop. Note that the filaments jiggle around a lot during such folding and unfolding events, but they always unfurl into a fully extended configuration when they move in a sustained manner. Proximal is left, distal is right for the axon that runs bottom left to top right. Time compression=30:1.|
|CM_21039_sm_SuppMovie5.mov||13561K||Movie 5. Moving and folding filaments (example 2). A single short filament moves across the field of view, pauses and folds up briefly along its entire length, then unfolds and resumes movement in the same direction. Note the uniformity of the fluorescence along the filament when it is moving, which indicates that it is in a fully extended configuration. Proximal is left, distal is right. Time compression=30:1.|
|CM_21039_sm_SuppMovie6.mov||6793K||Movie 6. Moving and folding filaments (example 3). This movie shows the movement of several filaments. Note the uniformity of the fluorescence along the filaments when they are undergoing sustained movement, which indicates that they are moving in a fully extended configuration. The movement of the long filament is interrupted by several pauses, including one in which it forms a short internal fold, then unfolds and resumes movement. A faster short filament subsequently moves past this long filament, overlapping it in several frames of the movie. The resulting local increase in brightness along the long filament should not be confused with folding. Proximal and distal orientation unknown. Time compression=30:1.|
|CM_21039_sm_SuppMovie7.mov||3265K||Movie 7. Moving and folding filaments (example 4). This is a short excerpt of a movie showing a retrogradely moving filament. The filament pauses briefly, then moves and pauses again. During the second pause its leading end folds back on itself, forming a hairpin loop. This folded filament then edges forward about 2µm, but the folded end unfolds before it resumes sustained movement. It may be necessary to step through the movie frame-by-frame to see this. A short anterogradely moving filament moves past the retrogradely moving filament during the second pause. Proximal is left, distal is right. Time compression=30:1.|
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