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Science 20 March 1987:
Vol. 235. no. 4795, pp. 1511 - 1514
DOI: 10.1126/science.2881354
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Articles

Science, Vol 235, Issue 4795, 1511-1514
Copyright © 1987 by American Association for the Advancement of Science

articles

F-actin and microtubule suspensions as indeterminate fluids

RE Buxbaum, T Dennerll, S Weiss, and Heidemann SR

The viscosity of F-actin and microtubule suspensions has been measured as a function of shear rate with a Weissenberg rheogoniometer. At shear rates of less than 1.0 per second the viscosity of suspensions of these two structural proteins is inversely proportional to shear rate. These results are consistent with previous in vivo measurements of the viscosity of cytoplasm. This power law implies that shear stress is independent of shear rate; that is, shear stress is a constant at all shear rates less than 1.0 per second. Thus the flow profile of these fluids is indeterminate, or nearly so. This flow property may explain several aspects of intracellular motility in living cells. Possible explanations for this flow property are based on a recent model for semidilute suspensions of rigid rods or a classical friction model for liquid crystals.


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Mechanical properties of cultured human airway smooth muscle cells from 0.05 to 0.4 Hz.
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J Appl Physiol 89, 1619-1632
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Opposing views on tensegrity as a structural framework for understanding cell mechanics.
D. E. Ingber, S. R. Heidemann, P. Lamoureux, and R. E. Buxbaum (2000)
J Appl Physiol 89, 1663-1678
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Direct Observations of the Mechanical Behaviors of the Cytoskeleton in Living Fibroblasts.
S. R. Heidemann, S. Kaech, R. E. Buxbaum, and A. Matus (1999)
J. Cell Biol. 145, 109-122
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Morphological bifurcations involving reaction-diffusion processes during microtubule formation.
J Tabony (1994)
Science 264, 245-248
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Microtubule self-organization is gravity-dependent.
C. Papaseit, N. Pochon, and J. Tabony (2000)
PNAS 97, 8364-8368
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