JCB logo
amgmicro.com
  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents
Published 4 August 2003. doi:10.1083/jcb.200301088
This Article
Right arrow Full Text
Right arrow Full Text (PDF, 365K)
Right arrow PPT slides of all figures
Right arrow Supplemental Material Index
Right arrow Alert me when this article is cited
Right arrow Citation Map
Services
Right arrow Email this article
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new content in the JCB
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Maddox, P.
Right arrow Articles by Salmon, E. D.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Maddox, P.
Right arrow Articles by Salmon, E. D.
Right arrowPubmed/NCBI databases
*Substance via MeSH
Social Bookmarking
Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Facebook   Add to Reddit   Add to Technorati   Add to Twitter  
What's this?

© The Rockefeller University Press, 0021-9525/2003/8/377 $5.00
The Journal of Cell Biology, Volume 162, Number 3, 377-382

Report

Direct observation of microtubule dynamics at kinetochores in Xenopus extract spindles

: implications for spindle mechanics



Paul Maddox1,2, Aaron Straight1,3, Peg Coughlin1,3, Timothy J. Mitchison1,3 and Edward D. Salmon1,2

1 Cell Division Group, Marine Biological Laboratory, Woods Hole, MA 02543
2 Department of Biology, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599
3 Department of Cell Biology, Harvard Medical School, Boston, MA 02115

Address correspondence to E.D. Salmon, Dept. of Biology, CB3280, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599. Tel.: (919) 962-2354. Fax: (919) 962-1625. email: tsalmon{at}email.unc.edu

Microtubule plus ends dynamically attach to kinetochores on mitotic chromosomes. We directly imaged this dynamic interface using high resolution fluorescent speckle microscopy and direct labeling of kinetochores in Xenopus extract spindles. During metaphase, kinetochores were stationary and under tension while plus end polymerization and poleward microtubule flux (flux) occurred at velocities varying from 1.5–2.5 µm/min. Because kinetochore microtubules polymerize at metaphase kinetochores, the primary source of kinetochore tension must be the spindle forces that produce flux and not a kinetochore-based mechanism. We infer that the kinetochore resists translocation of kinetochore microtubules through their attachment sites, and that the polymerization state of the kinetochore acts a "slip-clutch" mechanism that prevents detachment at high tension. At anaphase onset, kinetochores switched to depolymerization of microtubule plus ends, resulting in chromosome-to-pole rates transiently greater than flux. Kinetochores switched from persistent depolymerization to persistent polymerization and back again during anaphase, bistability exhibited by kinetochores in vertebrate tissue cells. These results provide the most complete description of spindle microtubule poleward flux to date, with important implications for the microtubule–kinetochore interface and for how flux regulates kinetochore function.

Key Words: kinetochore; fluorescent speckle microscopy; mitosis; centromere; anaphase

The online version of this article includes supplemental material.

Abbreviation used in this paper: FSM, fluorescent speckle microscopy.


Add to CiteULike CiteULike   Add to Complore Complore   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg   Add to Facebook Facebook   Add to Reddit Reddit   Add to Technorati Technorati   Add to Twitter Twitter    What's this?


This article has been cited by other articles:



  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents