Fast Microtubule Dynamics in Meiotic Spindles Measured by Single Imaging: Evidence that the Spindle Environment does not Stabilize Microtubules
Name
Needleman-2010-Fast Microtubule Dyn.pdf
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Author(s)
Mirny, Leonid A.
Mitchison, Timothy J.
Maresca, Tom
Ohi, Ryoma
Groen, Aaron
Needleman, Daniel J.
Date Issued
January 2010
Journal
Molecular Biology of the Cell
Publisher
American Society for Cell Biology
Citation
Needleman, Daniel J et al. “Fast Microtubule Dynamics in Meiotic Spindles Measured by Single Molecule Imaging: Evidence That the Spindle Environment Does Not Stabilize Microtubules.” Mol. Biol. Cell 21.2 (2010): 323-333. © 2010 American Society for Cell Biology.
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Final published version
Abstract
Metaphase spindles are steady-state ensembles of microtubules that turn over rapidly and slide poleward in some systems. Since the discovery of dynamic instability in the mid-1980s, models for spindle morphogenesis have proposed that microtubules are stabilized by the spindle environment. We used single molecule imaging to measure tubulin turnover in spindles, and nonspindle assemblies, in Xenopus laevis egg extracts. We observed many events where tubulin molecules spend only a few seconds in polymer and thus are difficult to reconcile with standard models of polymerization dynamics. Our data can be quantitatively explained by a simple, phenomenological model—with only one adjustable
parameter—in which the growing and shrinking of microtubule ends is approximated as a biased random walk. Microtubule turnover kinetics did not vary with position in the spindle and were the same in spindles and nonspindle ensembles nucleated by Tetrahymena pellicles. These results argue that the high density of microtubules in spindles compared with bulk cytoplasm is caused by local enhancement of nucleation and not by local stabilization. It follows that the key to understanding spindle morphogenesis will be to elucidate how nucleation is spatially controlled.
MIT Department
Harvard University--MIT Division of Health Sciences and Technology
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DOI of Published Version
http://dx.doi.org/10.1091/mbc.E09-09-0816
