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Fast Microtubule Dynamics In Meiotic Spindles Measured By Single Molecule Imaging: Evidence That The Spindle Environment Does Not Stabilize Microtubules, Thomas J. Maresca, D. J. Needleman, A. Groen, R. Ohi, L. Mirny, T. Mitchison
Fast Microtubule Dynamics In Meiotic Spindles Measured By Single Molecule Imaging: Evidence That The Spindle Environment Does Not Stabilize Microtubules, Thomas J. Maresca, D. J. Needleman, A. Groen, R. Ohi, L. Mirny, T. Mitchison
Thomas J. Maresca
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 …
Welcome To A New Kind Of Tension: Translating Kinetochore Mechanics Into A Wait-Anaphase Signal, Thomas J. Maresca, E. D. Salmon
Welcome To A New Kind Of Tension: Translating Kinetochore Mechanics Into A Wait-Anaphase Signal, Thomas J. Maresca, E. D. Salmon
Thomas J. Maresca
Recent high-resolution studies of kinetochore structure have transformed the way researchers think about this crucial macro-molecular complex, which is essential for ensuring chromosome segregation occurs faithfully during cell division. Kinetochores mediate the interaction between chromosomes and the plus-ends of dynamic spindle microtubules and control the timing of anaphase onset by regulating the spindle assembly checkpoint (SAC). There is much debate in the SAC research community as to whether mitotic cells sense only microtubule attachment at the kinetochore, or both attachment and tension, before committing to anaphase. In this Commentary, we present a brief history of the tension-versus-attachment debate, summarize recent …