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Micromechanical modeling of microtubules

Abstract : Microtubules serve as one of the structural components of the cell and take place in some of the important cellular functions such as mitosis and vesicular transport. Microtubules comprise of tubulin subunits tubulin dimers arranged in a cylindrical beta and formed by alpha hollow tube structure with a diameter of 20nm. They are typically comprised of 13 or 14 protofilaments arranged in spiral configurations. The longitudinal bonds between the tubulin dimers are much stiffer and stronger than the lateral bonds. This implies the anisotropic structure and properties of the microtubule. In this work, the aim is to define a complete set of elastic properties that capture the atomistic behavior and track the deformation of the microtubules under different loading conditions. A seamless microtubule wall is represented as a two dimensional triangulated lattice of dimers from which a representative volume element can be defined. A harmonic potential is adapted for the dimer–dimer interactions. Estimating the lattice elastic constants and following the methodology from the analysis of the mechanical behavior of triangulated spectrin network of the red blood cell membrane (Arslan and Boyce, 2006); a general continuum level constitutive model of the mechanical behavior of the microtubule lattice wall is developed. The model together with the experimental data given in the literature provides an insight to defining the parameters required for the discrete numerical model created in finite element analysis medium. The three point bending simulations for a microtubule modeled using shell elements, give tube bending stiffness values that are in accordance with the experimental bending stiffness values. The micrographs also show that shrinking ends of microtubules (due to microtubule instabilities) curl out. This implies the existence of prestress. A “connector model” is proposed to include the effect of the prestress and to capture the dynamic instabilities of microtubules.
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Submitted on : Friday, April 9, 2010 - 2:31:50 PM
Last modification on : Wednesday, October 14, 2020 - 3:52:46 AM
Long-term archiving on: : Wednesday, November 30, 2016 - 4:50:47 PM

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  • HAL Id : tel-00472078, version 1

Citation

Melis Arslan. Micromechanical modeling of microtubules. Mechanics [physics.med-ph]. École Nationale Supérieure des Mines de Paris, 2010. English. ⟨NNT : 2010ENMP1684⟩. ⟨tel-00472078⟩

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