Effect of weightlessness on colloidal particle transport and segregation in self-organising microtubule preparations

Abstract

Cortès. Effect of weightlessness on colloidal particle transport and segregation in self-organising microtubule preparations. Biophysical Chemistry, Elsevier, 2007, 127 (3) This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT ABSTRACTWeightlessness is known to effect cellular functions by as yet undetermined processes.Many experiments indicate a role of the cytoskeleton and microtubules. Under appropriate conditions in vitro microtubule preparations behave as a complex system that self-organises by a combination of reaction and diffusion. This process also results in the collective transport and organisation of any colloidal particles present. In large centimetre-sized samples, selforganisation does not occur when samples are exposed to a brief early period of weightlessness. Here, we report both space-flight and ground-based (clinorotation) experiments on the effect of w eightlessness on the transport and segregation of colloidal particles and chromosomes. In centimetre-sized containers, both methods show that a brief initial period of weightlessness strongly inhibits particle transport. In miniature cell-sized containers under normal gravity conditions, the particle transport that self-organisation causes results in their accumulation into segregated regions of high and low particle density. The gravity dependence of this behaviour is strongly shape dependent. In square wells, neither self-organisation nor particle transport and segregation occur under conditions of weightlessness. On the contrary, in rectangular canals, both phenomena are largely unaffected by weightlessness. These observations suggest, depending on factors such as cell and embryo shape, that major biological functions associated with microtubule driven particle transport and organisation might be strongly perturbed by weightlessness.

Mechanotransduction as an Adaptation to Gravity

“…Several studies have demonstrated that microtubules self-organization is influenced by the direction and magnitude of gravity (174, 175). Therefore, when cells are exposed to microgravity, microtubules experience a disruption of the radial pattern (176) showing a perinuclear clustering distribution (177).…”

Cytoskeletal Symmetry Breaking and Chirality: From Reconstituted Systems to Animal Development

“…The latter effect will lead to far-from equilibrium kinetics and spatially correlated dynamics at the macroscopic level most likely due to the liquid crystal-like properties of such dense solutions. It should be pointed out that these gravity-dependent phenomena are restricted to non-physiologically dense in vitro preparations and their in vivo relevance is controversial [50][51][52], especially since forces generated in microtubule assemblies are orders of magnitude greater than those generated by gravity. However, independent of the forces needed to organize microtubules into liquid crystal-like states, there is recent bona fide evidence of liquid crystal-like behavior of microtubules in cells [53,54].…”

Simulation of Microgravity by Magnetic Levitation and Random Positioning: Effect on Human A431 Cell Morphology

“…Interestingly, the virtual absence of gravity also had profound effects on the cellular and molecular level, including changes in cell morphology Hughes-Fulford et al 2003), modification of gene expression Hammond et al 1999;Liu and Wang 2008), changes in signal transduction cascades (de Groot et al 1991b;Ullrich et al 2008) and even changes in the selforganisation of tubulin (Papaseit et al 2000;Glade et al 2006;Tabony et al 2007).…”