The Ionic Environment of Rod-like Polyelectrolytes

1990 ◽  
pp. 69-80
Author(s):  
P. J. Rossky ◽  
C. S. Murthy ◽  
R. Bacquet
Keyword(s):  
Ionic Environment

Conformational characterization of nucleosome structure by Electron Microscopy

1993 ◽  
Vol 51 ◽  
pp. 194-195
Author(s):  
Gregory J. Czarnota
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Physiological State ◽  
Gene Activation ◽  
Three Dimensional ◽  
Macromolecular Complex ◽  
Ultrastructural Studies ◽  
Ionic Environment ◽  
Nucleosome Structure ◽  
Dimensional Reconstruction

Chromatin structure at the fundamental level of the nucleosome is important in vital cellular processes. Recent biochemical and genetic analyses show that nucleosome structure and structural changes are very active participants in gene expression, facilitating or inhibiting transcription and reflecting the physiological state of the cell. Structural states and transitions for this macromolecular complex, composed of DNA wound about a heterotypic octamer of variously modified histone proteins, have been measured by physico-chemical techniques and by enzyme-accessibility and are recognized to occur with various post-translational modifications, gene activation, transformation and with ionic-environment. In spite of studies which indicate various forms of nucleosome structure, all current x-ray and neutron diffraction studies have consistently resulted in only one structure, suggestive of a static conformation. In contrast, two-dimensional electron microscopy studies and three-dimensional reconstruction techniques have yielded different structures. These fundamental differences between EM and other ultrastructural studies have created a long standing quandary, which I have addressed and resolved using spectroscopic electron microscopy and statistical analyses of nucleosome images in a study of nucleosome structure with ionic environment.

THE EFFECT OF CHANGES OF THE IONIC ENVIRONMENT UPON AN ISOLATED CRUSTACEAN SENSORY NEURON

1963 ◽  
Vol 26 (6) ◽  
pp. 948-957 ◽  
Author(s):  
Charles Edwards ◽  
Carlo A. Terzuolo ◽  
Yoshiaki Washizu
Keyword(s):  
Sensory Neuron ◽  
Ionic Environment

Hollow fiber dead-end ultrafiltration: Influence of ionic environment on filtration of alginates

2008 ◽  
Vol 308 (1-2) ◽  
pp. 218-229 ◽  
Author(s):  
W.J.C. van de Ven ◽  
K. van’t Sant ◽  
I.G.M. Pünt ◽  
A. Zwijnenburg ◽  
A.J.B. Kemperman ◽  
...  
Keyword(s):  
Hollow Fiber ◽  
Ionic Environment ◽  
Dead End

Effect of an ionic environment on membrane fouling: a molecular dynamics study

2021 ◽  
Author(s):  
Shivam Tiwari ◽  
Abhijit Gogoi ◽  
K. Anki Reddy
Keyword(s):  
Molecular Dynamics ◽  
Graphene Oxide ◽  
Membrane Fouling ◽  
Md Simulations ◽  
Ionic Environment

The effect of the ionic environment on membrane fouling was investigated for polyamide (PA) and graphene oxide (GO) membranes using equilibrium molecular dynamics (MD) simulations.

scholarly journals Astrocytic modulation of information processing by layer 5 pyramidal neurons of the mouse visual cortex

2020 ◽  
Author(s):  
Dimitri Ryczko ◽  
Maroua Hanini-Daoud ◽  
Steven Condamine ◽  
Benjamin J. B. Bréant ◽  
Maxime Fougère ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Cortical Neurons ◽  
Calcium Binding ◽  
Pyramidal Neurons ◽  
Binding Protein ◽  
Contextual Information ◽  
Dendritic Tree ◽  
Cortical Layer ◽  
List Type ◽  
Ionic Environment

AbstractThe most complex cerebral functions are performed by the cortex which most important output is carried out by its layer 5 pyramidal neurons. Their firing reflects integration of sensory and contextual information that they receive. There is evidence that astrocytes influence cortical neurons firing through the release of gliotransmitters such as ATP, glutamate or GABA. These effects were described at the network and at the synaptic levels, but it is still unclear how astrocytes influence neurons input-output transfer function at the cellular level. Here, we used optogenetic tools coupled with electrophysiological, imaging and anatomical approaches to test whether and how astrocytic activation affected processing and integration of distal inputs to layer 5 pyramidal neurons (L5PN). We show that optogenetic activation of astrocytes near L5PN cell body prolonged firing induced by distal inputs to L5PN and potentiated their ability to trigger spikes. The observed astrocytic effects on L5PN firing involved glutamatergic transmission to some extent but relied on release of S100β, an astrocytic Ca2+-binding protein that decreases extracellular Ca2+ once released. This astrocyte-evoked decrease of extracellular Ca2+ elicited firing mediated by activation of Nav1.6 channels. Our findings suggest that astrocytes contribute to the cortical fundamental computational operations by controlling the extracellular ionic environment.Key Points SummaryIntegration of inputs along the dendritic tree of layer 5 pyramidal neurons is an essential operation as these cells represent the most important output carrier of the cerebral cortex. However, the contribution of astrocytes, a type of glial cell to these operations is poorly documented.Here we found that optogenetic activation of astrocytes in the vicinity of layer 5 in the mouse primary visual cortex induce spiking in local pyramidal neurons through Nav1.6 ion channels and prolongs the responses elicited in these neurons by stimulation of their distal inputs in cortical layer 1.This effect partially involved glutamatergic signalling but relied mostly on the astrocytic calcium-binding protein S100β, which regulates the concentration of calcium in the extracellular space around neurons.These findings show that astrocytes contribute to the fundamental computational operations of the cortex by acting on the ionic environment of neurons.

Ionic environment and hydrogen bonding in di-ureasil ormolytes doped with lithium triflate

2004 ◽  
Vol 702 (1-3) ◽  
pp. 39-48 ◽  
Author(s):  
S.C Nunes ◽  
V.de Zea Bermudez ◽  
D Ostrovskii ◽  
L.D Carlos
Keyword(s):  
Hydrogen Bonding ◽  
Lithium Triflate ◽  
Ionic Environment
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