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???displayArticle.abstract??? Microtubule dynamics underlie spindle assembly, yet we do not know how the spindle environment affects these dynamics. We developed methods for measuring two key parameters of microtubule plus-end dynamic instability in Xenopus egg extract spindles. To measure plus-end polymerization rates and localize growing plus ends, we used fluorescence confocal imaging of EB1. This revealed plus-end polymerization throughout the spindle at approximately 11 microm/min, similar to astral microtubules, suggesting polymerization velocity is not regionally regulated by the spindle. The ratio of EB1 to microtubule fluorescence revealed an enrichment of polymerizing ends near the spindle middle, indicating enhanced nucleation or rescue there. We measured depolymerization rates by creating a front of synchronized depolymerization in spindles severed with microneedles. This front could be tracked by polarization and fluorescence microscopy as it advanced from each cut edge toward the associated pole. Both imaging modalities revealed rapid depolymerization ( approximately 30 microm/min) superimposed on a subset of microtubules stable to depolymerization. Larger spindle fragments contained a higher percentage of stable microtubules, which we believe were oriented with their minus ends facing the cut. Depolymerization was blocked by the potent microtubule stabilizing agent hexylene glycol, but was unaffected by alpha-MCAK antibody and AMPPNP, which block catastrophe and kinesin motility, respectively. These measurements move us closer to understanding the complete life history of a spindle microtubule.
Belmont,
Identification of a protein that interacts with tubulin dimers and increases the catastrophe rate of microtubules.
1996, Pubmed,
Xenbase
Belmont,
Identification of a protein that interacts with tubulin dimers and increases the catastrophe rate of microtubules.
1996,
Pubmed
,
Xenbase Carazo-Salas,
Ran-GTP coordinates regulation of microtubule nucleation and dynamics during mitotic-spindle assembly.
2001,
Pubmed
,
Xenbase Desai,
Microtubule polymerization dynamics.
1997,
Pubmed Desai,
The use of Xenopus egg extracts to study mitotic spindle assembly and function in vitro.
1999,
Pubmed
,
Xenbase Forer,
Spindle birefringence of isolated mitotic apparatus: further evidence for two birefringent spindle components.
1976,
Pubmed Harris,
Conditions for assembly of tubulin-based structures in unfertilized sea urchin eggs. Spirals, monasters and cytasters.
1992,
Pubmed Hayden,
Kinetochores capture astral microtubules during chromosome attachment to the mitotic spindle: direct visualization in live newt lung cells.
1990,
Pubmed Heald,
Spindle assembly in Xenopus egg extracts: respective roles of centrosomes and microtubule self-organization.
1997,
Pubmed
,
Xenbase Hyman,
Preparation of modified tubulins.
1991,
Pubmed Inoué,
Force generation by microtubule assembly/disassembly in mitosis and related movements.
1995,
Pubmed Kalab,
Visualization of a Ran-GTP gradient in interphase and mitotic Xenopus egg extracts.
2002,
Pubmed
,
Xenbase Karsenti,
The mitotic spindle: a self-made machine.
2001,
Pubmed
,
Xenbase Kinoshita,
Reconstitution of physiological microtubule dynamics using purified components.
2001,
Pubmed
,
Xenbase Leslie,
Spindle microtubule dynamics following ultraviolet-microbeam irradiations of mitotic diatoms.
1984,
Pubmed Maddox,
Direct observation of microtubule dynamics at kinetochores in Xenopus extract spindles: implications for spindle mechanics.
2003,
Pubmed
,
Xenbase Mastronarde,
Interpolar spindle microtubules in PTK cells.
1993,
Pubmed Mitchison,
Properties of the kinetochore in vitro. II. Microtubule capture and ATP-dependent translocation.
1985,
Pubmed Nédélec,
Self-organisation and forces in the microtubule cytoskeleton.
2003,
Pubmed Nicklas,
Mechanically cut mitotic spindles: clean cuts and stable microtubules.
1989,
Pubmed Parsons,
Microtubule assembly in clarified Xenopus egg extracts.
1997,
Pubmed
,
Xenbase Rieder,
Mitosis through the microscope: advances in seeing inside live dividing cells.
2003,
Pubmed Sawin,
Poleward microtubule flux mitotic spindles assembled in vitro.
1991,
Pubmed
,
Xenbase Shelden,
Observation and quantification of individual microtubule behavior in vivo: microtubule dynamics are cell-type specific.
1993,
Pubmed Spurck,
UV microbeam irradiations of the mitotic spindle. II. Spindle fiber dynamics and force production.
1990,
Pubmed Spurck,
Ultraviolet microbeam irradiations of epithelial and spermatocyte spindles suggest that forces act on the kinetochore fibre and are not generated by its disassembly.
1997,
Pubmed Tirnauer,
EB1-microtubule interactions in Xenopus egg extracts: role of EB1 in microtubule stabilization and mechanisms of targeting to microtubules.
2002,
Pubmed
,
Xenbase Tirnauer,
EB1 targets to kinetochores with attached, polymerizing microtubules.
2002,
Pubmed Tournebize,
Control of microtubule dynamics by the antagonistic activities of XMAP215 and XKCM1 in Xenopus egg extracts.
2000,
Pubmed
,
Xenbase Tran,
A metastable intermediate state of microtubule dynamic instability that differs significantly between plus and minus ends.
1997,
Pubmed Trieselmann,
Ran localizes around the microtubule spindle in vivo during mitosis in Drosophila embryos.
2002,
Pubmed Vallotton,
Recovery, visualization, and analysis of actin and tubulin polymer flow in live cells: a fluorescent speckle microscopy study.
2003,
Pubmed
,
Xenbase Vasquez,
XMAP from Xenopus eggs promotes rapid plus end assembly of microtubules and rapid microtubule polymer turnover.
1994,
Pubmed
,
Xenbase Walker,
Asymmetric behavior of severed microtubule ends after ultraviolet-microbeam irradiation of individual microtubules in vitro.
1989,
Pubmed Waterman-Storer,
Fluorescent speckle microscopy, a method to visualize the dynamics of protein assemblies in living cells.
1998,
Pubmed
,
Xenbase Waters,
Pathways of spindle assembly.
1997,
Pubmed Wilde,
Ran stimulates spindle assembly by altering microtubule dynamics and the balance of motor activities.
2001,
Pubmed
,
Xenbase
