Density imbalances and free energy of lipid transfer in supported lipid bilayers
Chenyue Xing and Roland Faller
Supported lipid bilayers are an abundant research platform for understanding the behavior of real cell membranes as they allow for additional mechanical stability and at the same time have a fundamental structure approximating cell membranes. However, in computer simulations these systems have been ... [J. Chem. Phys. 131, 175104 (2009)] published Fri Nov 6, 2009.
Theory of a reconstructive structural transformation in capsids of icosahedral viruses
S. B. Rochal and V. L. Lorman
A theory of a reconstructive structural transformation in icosahedral capsid shells is developed for a whole family of virulent human viruses. It is shown that the reversible rearrangement of proteins during the virus maturation transformation is driven by the variation in the wave number l associat ... [Phys. Rev. E 80, 051905 (2009)] published Fri Nov 6, 2009.
Ubiquitous glassy relaxation in catalytic reaction networks
Akinori Awazu and Kunihiko Kaneko
Study of reversible catalytic reaction networks is important not only as an issue for chemical thermodynamics but also for protocells. From extensive numerical simulations and theoretical analysis, slow relaxation dynamics to sustain nonequlibrium states are commonly observed. These dynamics show tw ... [Phys. Rev. E 80, 041931 (2009)] published Fri Oct 30, 2009.
A Methodology to Analyze Changes in Lipid Core and Calcification Onto Fibrous Cap Vulnerability: The Human Atherosclerotic Carotid Bifurcation as an Illustratory Example
Dimitrios E. Kiousis, Stephan F. Rubinigg, Martin Auer, and Gerhard A. Holzapfel
A lipid core that occupies a high proportion of the plaque volume in addition to a thin fibrous cap is a predominant indicator of plaque vulnerability. Nowadays, noninvasive imaging modalities can identify such structural components, however, morphological criteria alone cannot reliably identify hig ... [J. Biomech. Eng. 131, 121002 (2009)] published Thu Oct 29, 2009.
Mechanical properties of interacting lipopolysaccharide membranes from bacteria mutants studied by specular and off-specular neutron scattering
Emanuel Schneck, Rafael G. Oliveira, Florian Rehfeldt, Bruno Deme, Klaus Brandenburg et al.
Specular and off-specular neutron scattering are used to study the influence of molecular chemistry (mutation) on the intermembrane interactions and mechanical properties of the outer membrane of Gram-negative bacteria consisting of lipopolysaccharides (LPSs). For this purpose, solid-supported multi ... [Phys. Rev. E 80, 041929 (2009)] published Wed Oct 28, 2009.
Traffic by multiple species of molecular motors
Yan Chai, Stefan Klumpp, Melanie J. I. Muller, and Reinhard Lipowsky
We study the traffic of two types of molecular motors using the two-species asymmetric simple exclusion process (ASEP) with periodic boundary conditions and with attachment and detachment of particles. We determine characteristic properties such as motor densities and currents by simulations and ana ... [Phys. Rev. E 80, 041928 (2009)] published Wed Oct 28, 2009.
Fluctuations of Ionic Current Through Lipid Bilayers at the Onset of Peptide Attacks and Pore Formation
G. C. Fadda, D. Lairez, and G. Zalczer
Voltage-clamp measurements on lipid bilayers at the onset of peptide attacks before pore formation are reported. With four different peptides [alamethicin, melittin, and two synthetic peptides of the leucine (L)lysine(K) copolymers (LK series)], correlations of conductivity fluctuations slowly decay ... [Phys. Rev. Lett. 103, 180601 (2009)] published Tue Oct 27, 2009.
Why Do Red Blood Cells Have Asymmetric Shapes Even in a Symmetric Flow?
Badr Kaoui, George Biros, and Chaouqi Misbah
Understanding why red blood cells (RBCs) move with an asymmetric shape (slipperlike shape) in small blood vessels is a long-standing puzzle in blood circulatory research. By considering a vesicle (a model system for RBCs), we discovered that the slipper shape results from a loss in stability of the ... [Phys. Rev. Lett. 103, 188101 (2009)] published Mon Oct 26, 2009.
Phase coexistence and line tension in ternary lipid systems
T. Idema, J. M. J. van Leeuwen, and C. Storm
The ternary system consisting of cholesterol, a saturated lipid, and an unsaturated one exhibits a rich phase behavior with multiple phase coexistence regimes. Remarkably, phase separation even occurs when each of the three binary systems consisting of two of these components is a uniform mixture. W ... [Phys. Rev. E 80, 041924 (2009)] published Fri Oct 23, 2009.
Force-velocity relations for multiple-molecular-motor transport
Ziqing Wang and Ming Li
A transition rate model of cargo transport by N molecular motors is proposed. Under the assumption of steady state, the force-velocity curve of multimotor system can be derived from the force-velocity curve of a single motor. Our work shows, in the case of low load, that the velocity of multimotor s ... [Phys. Rev. E 80, 041923 (2009)] published Thu Oct 22, 2009.
Three-dimensional model for the effective viscosity of bacterial suspensions
Brian M. Haines, Andrey Sokolov, Igor S. Aranson, Leonid Berlyand, and Dmitry A. Karpeev
We derive the effective viscosity of dilute suspensions of swimming bacteria from the microscopic details of the interaction of an elongated body with the background flow. An individual bacterium propels itself forward by rotating its flagella and reorients itself randomly by tumbling. Due to the ba ... [Phys. Rev. E 80, 041922 (2009)] published Thu Oct 22, 2009.
Noise and Synchronization in Pairs of Beating Eukaryotic Flagella
Raymond E. Goldstein, Marco Polin, and Idan Tuval
It has long been conjectured that hydrodynamic interactions between beating eukaryotic flagella underlie their ubiquitous forms of synchronization; yet there has been no experimental test of this connection. The biflagellate alga Chlamydomonas is a simple model for such studies, as its two flagella ... [Phys. Rev. Lett. 103, 168103 (2009)] published Fri Oct 16, 2009.
Predictions from a stochastic polymer model for the MinDE protein dynamics in Escherichia coli
Peter Borowski and Eric N. Cytrynbaum
The spatiotemporal oscillations of the Min proteins in the bacterium Escherichia coli play an important role in cell division. A number of different models have been proposed to explain the dynamics from the underlying biochemistry. Here, we extend a previously described discrete polymer model from ... [Phys. Rev. E 80, 041916 (2009)] published Mon Oct 12, 2009.
Kinetic overshoot in actin network assembly induced jointly by branching and capping proteins
Hyeran Kang, Anders E. Carlsson, and Jay X. Tang
We report an experimental study of the kinetics of actin assembly mediated by branching and capping proteins. Our findings confirm the recent prediction of a branching explosion occurring during polymerization. Fluorescence imaging shows a number of actin filaments with branches within a few minutes ... [Phys. Rev. E 80, 041913 (2009)] published Fri Oct 9, 2009.
Spontaneous Oscillations of a Minimal Actomyosin System under Elastic Loading
P.-Y. Placais, M. Balland, T. Guerin, J.-F. Joanny, and P. Martin
Spontaneous mechanical oscillations occur in various types of biological systems where groups of motor molecules are elastically coupled to their environment. By using an optical trap to oppose the gliding motion of a single bead-tailed actin filament over a substrate densely coated with myosin moto ... [Phys. Rev. Lett. 103, 158102 (2009)] published Fri Oct 9, 2009.
Pressure-temperature phase diagram for shapes of vesicles: A coarse-grained molecular dynamics study
Ping Liu, Ju Li, and Yong-Wei Zhang
Coarse-grained molecular dynamics simulations are performed to obtain the phase diagram for shapes of a vesicle with a variation in temperature and pressure difference across the membrane. Various interesting vesicle shapes are found, in particular, a series of shape transformations are observed for ... [Appl. Phys. Lett. 95, 143104 (2009)] published Tue Oct 6, 2009.
Computational analysis of the tether-pulling experiment to probe plasma membrane-cytoskeleton interaction in cells
Kristopher R. Schumacher, Aleksander S. Popel, Bahman Anvari, William E. Brownell, and Alexander A. Spector
Tethers are thin membrane tubes that can be formed when relatively small and localized forces are applied to cellular membranes and lipid bilayers. Tether pulling experiments have been used to better understand the fine membrane properties. These include the interaction between the plasma membrane a ... [Phys. Rev. E 80, 041905 (2009)] published Tue Oct 6, 2009.
Gated Narrow Escape Time for Molecular Signaling
Jurgen Reingruber and David Holcman
The mean time for a diffusing ligand to activate a target protein located on the surface of a microdomain can regulate cellular signaling. When the ligand switches between various states induced by chemical interactions or conformational changes, while target activation occurs in only one state, thi ... [Phys. Rev. Lett. 103, 148102 (2009)] published Wed Sep 30, 2009.
Reduction of Viscosity in Suspension of Swimming Bacteria
Andrey Sokolov and Igor S. Aranson
Measurements of the shear viscosity in suspensions of swimming Bacillus subtilis in free-standing liquid films have revealed that the viscosity can decrease by up to a factor of 7 compared to the viscosity of the same liquid without bacteria or with nonmotile bacteria. The reduction in viscosity is ... [Phys. Rev. Lett. 103, 148101 (2009)] published Tue Sep 29, 2009.
Fluctuation dynamics of spherical vesicles: Frustration of regular bulk dissipation into subdiffusive relaxation
Laura R. Arriaga, Ivan Lopez-Montero, Guillermo Orts-Gil, Bela Farago, Thomas Hellweg et al.
Spherical lipid vesicles obtained by the extrusion method are nonequilibrium membrane structures more curved than the zero spontaneous curvature equilibrium state of the bilayer. Furthermore, these structures are quite rigid as compared to spontaneous vesicles or microemulsion droplets made of solub ... [Phys. Rev. E 80, 031908 (2009)] published Mon Sep 21, 2009.
Static and alternating electric field and distance-dependent effects on carbon nanotube-assisted water self-diffusion across lipid membranes
Jose-Antonio Garate, Niall J. English, and J. M. D MacElroy
Water-self-diffusion through single-walled carbon nanotubes (SWCNTs) inserted normal to a phospholipid membrane has been studied using equilibrium and nonequilibrium molecular dynamics simulations in the presence of static and alternating electrical fields. Four different SWCNTs were investigated: ( ... [J. Chem. Phys. 131, 114508 (2009)] published Fri Sep 18, 2009.