scholarly journals Controlling septin filament flexibility and bundling

2017 ◽  
Author(s):  
Anum Khan ◽  
Jay Newby ◽  
Amy S Gladfelter
Keyword(s):  
Physical Properties ◽  
Relative Proportion ◽  
Higher Order ◽  
Membrane Properties ◽  
Guanine Nucleotide ◽  
Filament Length ◽  
Cell Morphogenesis ◽  
Biophysical Properties ◽  
Nucleotide Hydrolysis ◽  
Septin Filament

Septins self-assemble into heteromeric rods and filaments to act as scaffolds and modulate membrane properties. How cells tune the biophysical properties of septin filaments to control filament flexibility and length, and in turn the size, shape, and position of higher-order septin structures is not well understood. We examined how rod composition and nucleotide availability influence physical properties of septins such as annealing, fragmentation, bundling and bending. We found that septin complexes have symmetric termini, even when both Shs1 and Cdc11 are coexpressed. The relative proportion of Cdc11/Shs1 septin complexes controls the biophysical properties of filaments and influences the rate of annealing, fragmentation, and filament flexibility. Additionally, the presence and exchange of guanine nucleotide also alters filament length and bundling. An Shs1 mutant that is predicted to alter nucleotide hydrolysis has altered filament length and dynamics in cells and impacts cell morphogenesis. These data show that modulating filament properties through rod composition and nucleotide binding can control formation of septin assemblies that have distinct physical properties and functions.

scholarly journals Control of septin filament flexibility and bundling

2017 ◽  
Author(s):  
Anum Khan ◽  
Jay Newby ◽  
Amy S. Gladfelter
Keyword(s):  
Physical Properties ◽  
Relative Proportion ◽  
Higher Order ◽  
Membrane Properties ◽  
Guanine Nucleotide ◽  
Filament Length ◽  
Cell Morphogenesis ◽  
Biophysical Properties ◽  
Nucleotide Hydrolysis ◽  
Septin Filament

AbstractSeptins self-assemble into heteromeric rods and filaments to act as scaffolds and modulate membrane properties. How cells tune the biophysical properties of septin filaments to control filament flexibility and length, and in turn the size, shape, and position of higher-order septin structures is not well understood. We examined how rod composition and nucleotide availability influence physical properties of septins such as annealing, fragmentation, bundling and bending. We found that septin complexes have symmetric termini, even when both Shs1 and Cdc11 are coexpressed. The relative proportion of Cdc11/Shs1 septin complexes controls the biophysical properties of filaments and influences the rate of annealing, fragmentation, and filament flexibility. Additionally, the presence and exchange of guanine nucleotide also alters filament length and bundling. An Shs1 mutant that is predicted to alter nucleotide hydrolysis has altered filament length and dynamics in cells and impacts cell morphogenesis. These data show that modulating filament properties through rod composition and nucleotide binding can control formation of septin assemblies that have distinct physical properties and functions.

scholarly journals Control of septin filament flexibility and bundling by subunit composition and nucleotide interactions

2018 ◽  
Vol 29 (6) ◽  
pp. 702-712 ◽  
Author(s):  
Anum Khan ◽  
Jay Newby ◽  
Amy S. Gladfelter
Keyword(s):  
Physical Properties ◽  
Relative Proportion ◽  
Membrane Properties ◽  
Guanine Nucleotide ◽  
Filament Length ◽  
Cell Morphogenesis ◽  
Biophysical Properties ◽  
Nucleotide Hydrolysis ◽  
Nucleotide Interactions ◽  
Septin Filament

Septins self-assemble into heteromeric rods and filaments to act as scaffolds and modulate membrane properties. How cells tune the biophysical properties of septin filaments to control filament flexibility and length, and in turn the size, shape, and position of higher-order septin structures, is not well understood. We examined how rod composition and nucleotide availability influence physical properties of septins such as annealing, fragmentation, bundling, and bending. We found that septin complexes have symmetric termini, even when both Shs1 and Cdc11 are coexpressed. The relative proportion of Cdc11/Shs1 septin complexes controls the biophysical properties of filaments and influences the rate of annealing, fragmentation, and filament flexibility. Additionally, the presence and apparent exchange of guanine nucleotide also alters filament length and bundling. An Shs1 mutant that is predicted to alter nucleotide hydrolysis has altered filament length and dynamics in cells and impacts cell morphogenesis. These data show that modulating filament properties through rod composition and nucleotide binding can control formation of septin assemblies that have distinct physical properties and functions.

scholarly journals Characterization of Ion Exchange Membranes with Special Surface Structure

2017 ◽  
Author(s):  
Eliška Stránská ◽  
Kristýna Weinertová ◽  
David Neděla ◽  
Jan Křivčík
Keyword(s):  
Ion Exchange ◽  
Physical Properties ◽  
Surface Structure ◽  
Flat Surface ◽  
Ion Exchange Membrane ◽  
Membrane Properties ◽  
Ion Exchange Membranes ◽  
Geometrical Structures ◽  
Special Surface ◽  
Exchange Membrane

This article focuses on the preparation of the heterogeneous ion exchange membrane with a special surface structure made with three types of knitted fabric. The special surface structure of ion exchange membranes can be useful for the intensification of mass transfer processes in electrodialysis.Three types of structured ion exchange membranes were prepared together with a membrane with a flat surface to compare the influence of geometrical structures on the behaviour of ion exchange membrane properties. Electrochemical, mechanical and physical properties were determined. Structured membranes exhibited comparable electrochemical and physical properties to the flat ion exchange membrane. Some transport parameters were measured in an electrodialysis stack with two concentrations of solution. Two electrodialysis stacks with different sizes of active area were used for comparison. Improving efficiency and mass flux was not confirmed. It was not demonstrated that structured IEMs were not better than IEMs with the flat surface.

Electro-Optic and Non-Linear Optical Coefficients of (Pb, La)(Zr, Ti)O3, BaTiO3, (Sr, Ba)Nb2O6 and Ba2NaNb5O15 Thin Films

1990 ◽  
Vol 200 ◽  
Author(s):  
A. Y. Wu ◽  
Feiling Wang ◽  
Ching-Bo Juang ◽  
Carlos Bustamante
Keyword(s):  
Thin Films ◽  
Physical Properties ◽  
Higher Order ◽  
Fused Silica ◽  
Optical Polarization ◽  
Electro Optic ◽  
Non Linear ◽  
Confocal Scanning ◽  
Linear Optical ◽  
Sputter Deposited

ABSTRACTThe electro-optic properties of sputter-deposited PLZT, BaTiO3, SBN, and BNN films on fused silica substrates have been studied using a confocal scanning optical polarization microscope. The Pockels, Kerr, and higher order electro-optic coefficients and their relations to the non-linear optical coefficients in the films are presented. The materials and physical properties of the films are discussed.

On Some Physical Properties of a Unified Lepton-Hadron Field Model with Composte Bosons

1982 ◽  
Vol 37 (11) ◽  
pp. 1295-1300 ◽  
Author(s):  
H. Stumpf
Keyword(s):  
Physical Properties ◽  
Permutation Group ◽  
Field Model ◽  
Higher Order ◽  
Lepton Number ◽  
Third Order ◽  
First Order ◽  
Unified Field ◽  
Intrinsic Parity ◽  
Pseudo Color

In preceding papers a lepton-hadron unified field model was introduced by means of a third order nonlinear spinorfield equation. In this paper an improved interpretation to this model is given which tries to incorporate the advantages of various current matter models and to avoid their drawbacks. In particular charge and lepton number are introduced, while the extended unstable baryon states are distinguished from lepton states by an intrinsic parity. A theorem is derived which allows a biunique decomposition of the nonlinear higher order spinorfield equation into nonlinear first order spinorfield equations and the simultaneous introduction of a permutation group of the subfields. These subfields are identified as pseudo-color fields.

scholarly journals Distinct Firing Properties of Higher Order Thalamic Relay Neurons

2003 ◽  
Vol 90 (1) ◽  
pp. 291-299 ◽  
Author(s):  
Jianli Li ◽  
Martha E. Bickford ◽  
William Guido
Keyword(s):  
Membrane Depolarization ◽  
Firing Frequency ◽  
Higher Order ◽  
Membrane Properties ◽  
Repetitive Firing ◽  
Membrane Hyperpolarization ◽  
First Order ◽  
Current Pulses ◽  
Response Modes ◽  
Relay Neurons

It has been proposed that the thalamus is composed of at least two types of nuclei. First-order relay nuclei transmit signals from the periphery to the cortex while higher order nuclei may route information from one cortical area to another. Although much is known about the functional properties of relay neurons in first-order nuclei, little is known about relay neurons belonging to higher-order nuclei. We investigated the electrophysiological properties of relay cells in a higher-order thalamic nucleus using in vitro intracellular recordings from thalamic slices of the rat's lateral posterior nucleus (LPN). We found neurons of the LPN possess many of the same membrane properties as first-order relay neurons. These included low-threshold calcium spikes ( IT) and burst firing, a mixed cation conductance ( IH) that prevented membrane hyperpolarization, and a transient K+ conductance that delayed spike firing ( IA). The repetitive firing characteristics of LPN neurons were more distinct. One group of cells, located in the more caudal regions of the LPN responded to depolarizing current pulses with a train of action potentials or in a regular spiking (RS) mode. This form of firing showed a steep but highly linear increase in firing frequency with increasing levels of membrane depolarization. Another group of cells, located in the more rostral regions of the LPN, responded to depolarizing current pulses with clusters of high-frequency bursts or in a clustered spiking (CS) mode. The overall firing frequency rose nonlinearly with membrane depolarization, but the frequency of a given burst remained relatively constant. The caudal LPN receives input from the superior colliculus, whereas the rostral LPN receives input from layers V and VI of the visual cortex. Thus the RS and CS cells may be driven by subcortical and cortical inputs respectively, and the distinct temporal properties of their response modes may be a necessary component of the LPN circuitry.

scholarly journals Cytoskeletal mechanics and dynamics in theDrosophilasyncytial embryo

2021 ◽  
Vol 134 (4) ◽  
pp. jcs246496
Author(s):  
Zhiyi Lv ◽  
Jorge de-Carvalho ◽  
Ivo A. Telley ◽  
Jörg Großhans
Keyword(s):  
Physical Properties ◽  
Molecular Motors ◽  
Dynamic Networks ◽  
Cellular Function ◽  
Biophysical Properties ◽  
Physical Separation ◽  
The Past ◽  
Cytoskeletal Dynamics ◽  
Associated Proteins ◽  
Biochemical Signals

ABSTRACTCell and tissue functions rely on the genetic programmes and cascades of biochemical signals. It has become evident during the past decade that the physical properties of soft material that govern the mechanics of cells and tissues play an important role in cellular function and morphology. The biophysical properties of cells and tissues are determined by the cytoskeleton, consisting of dynamic networks of F-actin and microtubules, molecular motors, crosslinkers and other associated proteins, among other factors such as cell–cell interactions. TheDrosophilasyncytial embryo represents a simple pseudo-tissue, with its nuclei orderly embedded in a structured cytoskeletal matrix at the embryonic cortex with no physical separation by cellular membranes. Here, we review the stereotypic dynamics and regulation of the cytoskeleton inDrosophilasyncytial embryos and how cytoskeletal dynamics underlies biophysical properties and the emergence of collective features. We highlight the specific features and processes of syncytial embryos and discuss the applicability of biophysical approaches.

scholarly journals Biophysical properties governing septin assembly

2021 ◽  
Author(s):  
Benjamin L Woods ◽  
Ian L Seim ◽  
Jessica Liu ◽  
Grace McLaughlin ◽  
Kevin S. Cannon ◽  
...  
Keyword(s):  
Physical Model ◽  
Yeast Extract ◽  
Cell Membranes ◽  
Regulatory Proteins ◽  
Biophysical Properties ◽  
Regulatory Mutants ◽  
Filament Assembly ◽  
Pure Protein ◽  
Crowded Environments ◽  
Septin Filament

Septin filaments build structures such as rings, lattices and gauzes that serve as platforms for localizing signaling and organizing cell membranes. How cells control the geometry of septin assemblies in poorly understood. We show here that septins are isodesmic polymers, in contrast to cooperative polymerization exhibited by F-actin and microtubules. We constructed a physical model to analyze and interpret how septin assemblies change in the presence of regulators in yeast extracts. Notably filaments differ in length and curvature in yeast extract compared to pure protein indicating cellular regulators modulate intrinsic biophysical features. Combining analysis of extracts from regulatory mutants with simulations, we found increased filament flexibility and reduced filament fragmentation promote assembly of septin rings, whereas reduced flexibility in crowded environments promotes local filament alignment. This work demonstrates how tuning of intrinsic features of septin filament assembly by regulatory proteins yields a diverse array of structures observed in cells.

scholarly journals Relaxin Affects Smooth Muscle Biophysical Properties and Mechanical Activity of the Female Mouse Colon

Endocrinology ◽  
2015 ◽  
Vol 156 (12) ◽  
pp. 4398-4410 ◽  
Author(s):  
Roberta Squecco ◽  
Rachele Garella ◽  
Eglantina Idrizaj ◽  
Silvia Nistri ◽  
Fabio Francini ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Smooth Muscle ◽  
Protein Kinase ◽  
Guanylate Cyclase ◽  
Membrane Properties ◽  
Mechanical Activity ◽  
Biophysical Properties ◽  
Dependent Protein Kinase ◽  
Cgmp Dependent Protein Kinase ◽  
Dependent Protein

The hormone relaxin (RLX) has been reported to influence gastrointestinal motility in mice. However, at present, nothing is known about the effects of RLX on the biophysical properties of the gastrointestinal smooth muscle cells (SMCs). Other than extending previous knowledge of RLX on colonic motility, the purpose of this study was to investigate the ability of the hormone to induce changes in resting membrane potential (RMP) and on sarcolemmal ion channels of colonic SMCs of mice that are related to its mechanical activity. To this aim, we used a combined mechanical and electrophysiological approach. In the mechanical experiments, we observed that RLX caused a decay of the basal tone coupled to an increase of the spontaneous contractions, completely abolished by the guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]-quinoxalin-1-one (ODQ). The electrophysiological results indicate for the first time that RLX directly affects the SMC biophysical properties inducing hyperpolarization of RMP and cycles of slow hyperpolarization/depolarization oscillations. The effects of RLX on RMP were abolished by ODQ as well as by a specific inhibitor of the cGMP-dependent protein kinase, KT5823. RLX reduced Ca2+ entry through the voltage-dependent L-type channels and modulated either voltage- or ATP-dependent K+ channels. These effects were abolished by ODQ, suggesting the involvement of the nitric oxide/guanylate cyclase pathway in the effects of RLX on RMP and ion channel modulation. These actions of RLX on membrane properties may contribute to the regulation of the proximal colon motility by the nitric oxide/cGMP/cGMP-dependent protein kinase pathway.

Tackling the biophysical properties of sphingolipids to decipher their biological roles

2015 ◽  
Vol 396 (6-7) ◽  
pp. 597-609 ◽  
Author(s):  
Ana C. Carreira ◽  
Ana E. Ventura ◽  
Ana R.P. Varela ◽  
Liana C. Silva
Keyword(s):  
Physical Properties ◽  
State Of The Art ◽  
The State ◽  
Biophysical Properties ◽  
Sphingoid Bases ◽  
Structural Alterations ◽  
Lipid Interactions ◽  
Cellular Events

Abstract From the most simple sphingoid bases to their complex glycosylated derivatives, several sphingolipid species were shown to have a role in fundamental cellular events and/or disease. Increasing evidence places lipid-lipid interactions and membrane structural alterations as central mechanisms underlying the action of these lipids. Understanding how these molecules exert their biological roles by studying their impact in the physical properties and organization of membranes is currently one of the main challenges in sphingolipid research. Herein, we review the progress in the state-of-the-art on the biophysical properties of sphingolipid-containing membranes, focusing on sphingosine, ceramides, and glycosphingolipids.

Sign in / Sign up

Export Citation Format

Share Document