The role of calcium in membrane condensation and spontaneous curvature variations in model lipidic systems

2011 ◽  
Vol 13 (8) ◽  
pp. 3115-3125 ◽  
Author(s):  
Anan Yaghmur ◽  
Barbara Sartori ◽  
Michael Rappolt
Keyword(s):  
Spontaneous Curvature

Blocked Lipid Exchange in Bilayers and its Possible Influence on the Shape of Vesicles

1974 ◽  
Vol 29 (9-10) ◽  
pp. 510-515 ◽  
Author(s):  
W Helfrich
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Spontaneous Curvature ◽  
Lipid Exchange ◽  
Lipid Distribution ◽  
Shape Transformations ◽  
Curvature Elasticity ◽  
Possible Cause

Abstract The role of lipid exchange in the curvature elasticity of bilayers is studied theoretically. Blocking of exchange between the monolayers may give rise to a nonequilibrium lipid distribution going hand in hand with a spontaneous curvature. Some possible consequences for vesicular deformations are discussed. Lipid nonequilibrium is tentatively suggest as one possible cause for certain shape transformations of red blood cells

Membrane Curvature Induced by Sugar and Polymer Solutions

1997 ◽  
Vol 489 ◽  
Author(s):  
H.-G. Döbereiner ◽  
A. Lehmann ◽  
W. Goedel ◽  
O. Selchow ◽  
R. Lipowsky
Keyword(s):  
Polymer Solutions ◽  
Lipid Vesicles ◽  
Membrane Curvature ◽  
Elastic Membrane ◽  
Spontaneous Curvature ◽  
Membrane Asymmetry ◽  
Bending Modulus ◽  
Bending Elasticity ◽  
Cellular Organelles

AbstractWe monitor the effect of transversal membrane asymmetry on the morphology of giant uni-lamellar vesicles in sugar and polymer solutions. The shapes of fluid lipid vesicles are governed by the bending elasticity of their membrane which is characterized by the bending modulus and the spontaneous curvature of the bilayer. We present a recently developed technique for the measurement of the spontaneous curvature using quantitative phase contrast microscopy. Different mechanisms for elastic membrane asymmetry and the role of the bending energy concept for the morphology of cellular organelles are discussed.

scholarly journals A Biophysical Model for Plant Cell Plate Development

2020 ◽  
Author(s):  
Muhammad Zaki Jawaid ◽  
Rosalie Sinclair ◽  
Daniel Cox ◽  
Georgia Drakakaki
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Late Stage ◽  
Cell Plate ◽  
Biophysical Model ◽  
Synthesis Rate ◽  
Spontaneous Curvature ◽  
Two Dimensional ◽  
A Cell

AbstractPlant cytokinesis, a fundamental process of plant life, involves de novo formation of a ‘cell plate’ that partitions the cytoplasm of the dividing cell. Cell plate formation is directed by orchestrated delivery, fusion of cytokinetic vesicles, and membrane maturation to the form the nascent cell wall by the timely deposition of polysaccharides such as callose, cellulose, and crosslinking glycans. In contrast to the role of endomembrane protein regulators the role of polysaccharides, in cell plate development is poorly understood. Callose, a β-1-3 glucan polymer, is transiently accumulated during cell plate expansion to be replaced by cellulose in mature stages. Based on the severity of cytokinesis defects in the absence of callose, it has been proposed that it stabilizes this membrane network structure. However, there is currently no theory to understand its role in cytokinesis.Here we extend the Helfrich free energy model for membranes including a phenomenological spreading force as an “areal pressure” generated by callose and/or other polysaccharides. Regular cell plate development in the model is possible, with suitable bending modulus, for a two-dimensional late stage spreading force parameter of between 2–6pN/nm, an osmotic pressure difference of 2–10kPa, and spontaneous curvature between 0–0.04nm−1. With these conditions, stable membrane conformation sizes and morphologies emerge in concordance with stages of cell plate development. With no spreading force, the cell plate fails to mature properly, corroborating experimental observations of cytokinesis arrest in the absence of callose. To reach a nearly mature cell plate, our model requires the late stage onset that the spreading force coupled with a concurrent loss of spontaneous curvature. A simple model based upon production of callose as a quasi-two-dimensional self-avoiding polymer produces the correct phenomenological form of the spreading force, which will be further refined, since matching to our numbers requires an exceptionally high callose synthesis rate.Significance StatementPlant cell division features the development of a unique membrane network called the cell plate that matures to a cell wall which separates the two daughter cells. During cell plate development, callose, a β-1-3 glucan polymer, is transiently synthesized at the cell plate only to be replaced by cellulose in mature stages. The role for this transient callose accumulation at the cell plate is unknown. It has been suggested that callose provides mechanical stability, as well as a spreading force that widens and expands tubular and fenestrated cell plate structures to aid the maturation of the cell plate. Chemical inhibition of callose deposition results in the failure of cell plate development supporting this hypothesis. This publication establishes the need for a spreading force in cell plate development using a biophysical model that predicts cell plate development in the presence and the absence of this force. Such models can potentially be used to decipher for the transition/maturation of membrane networks upon the deposition of polysaccharide polymers.

scholarly journals Dynamics of pearling instability in polymersomes: The role of shear membrane viscosity and spontaneous curvature

2021 ◽  
Vol 33 (12) ◽  
pp. 122016
Author(s):  
J. Lyu ◽  
K. Xie ◽  
R. Chachanidze ◽  
A. Kahli ◽  
G. Boëdec ◽  
...  
Keyword(s):  
Spontaneous Curvature ◽  
Membrane Viscosity

Smectic‐Ato bilayer evolution in concentrated surfactant solutions: The role of spontaneous curvature

1994 ◽  
Vol 101 (5) ◽  
pp. 4331-4342 ◽  
Author(s):  
Rony Granek ◽  
William M. Gelbart ◽  
Yardena Bohbot ◽  
Avinoam Ben‐Shaul
Keyword(s):  
Spontaneous Curvature ◽  
Surfactant Solutions

scholarly journals The glycolipid GM1 reshapes asymmetric biomembranes and giant vesicles by curvature generation

2018 ◽  
Vol 115 (22) ◽  
pp. 5756-5761 ◽  
Author(s):  
Raktim Dasgupta ◽  
Markus S. Miettinen ◽  
Nico Fricke ◽  
Reinhard Lipowsky ◽  
Rumiana Dimova
Keyword(s):  
Spontaneous Curvature ◽  
Intensity Analysis ◽  
Ganglioside Gm1 ◽  
Local Curvature ◽  
Giant Vesicles ◽  
Neuron Morphology ◽  
Receptor Proteins ◽  
Neuronal Membranes ◽  
Dynamics Simulations

The ganglioside GM1 is present in neuronal membranes at elevated concentrations with an asymmetric spatial distribution. It is known to generate curvature and can be expected to strongly influence the neuron morphology. To elucidate these effects, we prepared giant vesicles with GM1 predominantly present in one leaflet of the membrane, mimicking the asymmetric GM1 distribution in neuronal membranes. Based on pulling inward and outward tubes, we developed a technique that allowed the direct measurement of the membrane spontaneous curvature. Using vesicle electroporation and fluorescence intensity analysis, we were able to quantify the GM1 asymmetry across the membrane and to subsequently estimate the local curvature generated by the molecule in the bilayer. Molecular-dynamics simulations confirm the experimentally determined dependence of the membrane spontaneous curvature as a function of GM1 asymmetry. GM1 plays a crucial role in connection with receptor proteins. Our results on curvature generation of GM1 point to an additional important role of this ganglioside, namely in shaping neuronal membranes.

Role of dactinomycin in the improved survival of children with Wilms' tumor

JAMA ◽  
1966 ◽  
Vol 195 (12) ◽  
pp. 1005-1009 ◽  
Author(s):  
D. J. Fernbach
Keyword(s):  
Wilms Tumor

Role of the allergist in diagnosis and management of patients with uveitis

JAMA ◽  
1966 ◽  
Vol 195 (3) ◽  
pp. 167-172 ◽  
Author(s):  
T. E. Van Metre
Keyword(s):  
Diagnosis And Management

The power of norms to sway fused group members

2018 ◽  
Vol 41 ◽  
Author(s):  
Winnifred R. Louis ◽  
Craig McGarty ◽  
Emma F. Thomas ◽  
Catherine E. Amiot ◽  
Fathali M. Moghaddam
Keyword(s):  
Evolutionary Anthropology ◽  
Normative Systems ◽  
Violent Extremism ◽  
Identity Fusion ◽  
Group Members

AbstractWhitehouse adapts insights from evolutionary anthropology to interpret extreme self-sacrifice through the concept of identity fusion. The model neglects the role of normative systems in shaping behaviors, especially in relation to violent extremism. In peaceful groups, increasing fusion will actually decrease extremism. Groups collectively appraise threats and opportunities, actively debate action options, and rarely choose violence toward self or others.

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