Measurements of Ion-Motive Force Across the Cell Membrane

2017 ◽  
pp. 193-201
Author(s):  
Tsai-Shun Lin ◽  
Yi-Ren Sun ◽  
Chien-Jung Lo
Keyword(s):  
Cell Membrane ◽  
Motive Force

scholarly journals Chaperone mediated coupling of subunit availability to activation of flagellar Type III Secretion

2020 ◽  
Author(s):  
Owain J. Bryant ◽  
Betty Y-W. Chung ◽  
Gillian M. Fraser
Keyword(s):  
Cell Membrane ◽  
Electric Potential ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Proton Motive Force ◽  
Secretion System ◽  
Motive Force ◽  
Type Iii

AbstractBacterial flagellar subunits are exported across the cell membrane by the flagellar Type III Secretion System (fT3SS), powered by the proton motive force (pmf) and a specialized ATPase that enables the flagellar export gate to utilise the pmf electric potential (ΔΨ). Export gate activation is mediated by the ATPase stalk, FliJ, but how this process is regulated to prevent wasteful dissipation of pmf in the absence of subunit cargo is not known. Here, we show that FliJ activation of the export gate is regulated by flagellar export chaperones. FliJ binds unladen chaperones and, using novel chaperone variants specifically defective for FliJ binding, we show that disruption of this interaction attenuates motility and cognate subunit export. We demonstrate in vitro that chaperones and the FlhA export gate component compete for binding to FliJ, and show in vivo that unladen chaperones, which would be present in the cell when subunit levels are low, sequester FliJ to prevent activation of the export gate and attenuate subunit export. Our data indicate a mechanism whereby chaperones couple availability of subunit cargo to pmf-driven export by the fT3SS.

scholarly journals The Response of Bacterial Flagellar Motor to Stepwise Increase in NaCl Concentration

2020 ◽  
Author(s):  
V. Soman ◽  
S. Kumari ◽  
S. Nath ◽  
R. Elangovan
Keyword(s):  
Membrane Potential ◽  
Cell Membrane ◽  
Salmonella Enteritidis ◽  
Proton Motive Force ◽  
Motive Force ◽  
Flagellar Motor ◽  
Stepwise Increase ◽  
Flagellar Motors ◽  
Nacl Concentration ◽  
Bacterial Flagellar Motor

AbstractMany species of bacteria use flagella to navigate in its environment. The flagellum is a 7-10 μm long helical filament with a rotary motor at its base embedded in the cell membrane and almost a dozen stator complexes. Proton motive force across the cell membrane powers the flagellar motors of E.coli and Salmonella. The motor stochastically switches between clockwise and counter-clockwise direction. A chemotaxis system causes the motor to change its direction, but the process is more complex as the switch is sensitive to load and proton motive force as well. NaCl is significant with regard to the flagellar motor as it affects the stator dynamics, proton motive force, and osmotaxis at higher concentration. Chemotaxis helps the bacteria for its growth and survival. E.coli’s natural habitat has high osmolarity and the organism uses use various mechanisms for osmoregulation. However, the role of flagellar motor to adapt to the changes in osmolarity, or osmotaxis, is not well studied. In this work, we dissipated the membrane potential of bacteria in pH 7 using step-wise increase in concentration of NaCl in motility buffer and studied the output of E.coli’s flagellar motor using tethered bead assay and swimming Salmonella enteritidis cells. We observed decrease in motor speed and switching rates with stepwise increase in NaCl concentration in the motility buffer. The mean speed of the motors decreased with NaCl concentration. The population of swimming cells tumbled more with increase in concentration of NaCl. At the single motor level, the motors biased to CCW rotation with decrease in membrane potential. In this study, we present our observations of the flagellar motor in high NaCl concentration, and explore how NaCl can be used to study various aspects of the bacterial flagellar motor.Statement of significanceSodium ion has been significant in the both the cellular energetics and the function of bacterial flagellar motor. Growing evidence show that the effect of sodium ions was not what hitherto thought it would be. It is involved in the sodium energetics, dissipate membrane potential, affect the flagellar stator dynamics of bacteria. Being an osmolyte, it influences the osmotaxis of bacteria. In this work, we studied the effect of NaCl on the response of the single bacterial flagellar motor of E.coli and swimming cells of Salmonella enteritidis. We observed that the effect of NaCl on the output of the flagellar motor was significant and it may affect the cells in various ways.

Sarcolemmal permeability changes during early myocardial anoxia

1978 ◽  
Vol 36 (2) ◽  
pp. 642-643
Author(s):  
M. Ashraf ◽  
L. Landa ◽  
L. Nimmo ◽  
C. M. Bloor
Keyword(s):  
Cell Membrane ◽  
Membrane Permeability ◽  
Coronary Artery Occlusion ◽  
Artery Occlusion ◽  
Cell Membrane Permeability ◽  
Enzyme Release ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Sarcolemmal Permeability ◽  
Membrane Changes

Following coronary artery occlusion, the myocardial cells lose intracellular enzymes that appear in the serum 3 hrs later. By this time the cells in the ischemic zone have already undergone irreversible changes, and the cell membrane permeability is variably altered in the ischemic cells. At certain stages or intervals the cell membrane changes, allowing release of cytoplasmic enzymes. To correlate the changes in cell membrane permeability with the enzyme release, we used colloidal lanthanum (La+++) as a histological permeability marker in the isolated perfused hearts. The hearts removed from sprague-Dawley rats were perfused with standard Krebs-Henseleit medium gassed with 95% O2 + 5% CO2. The hypoxic medium contained mannitol instead of dextrose and was bubbled with 95% N2 + 5% CO2. The final osmolarity of the medium was 295 M osmol, pH 7. 4.

Flagellar Attachment in Selected Trypanosomes

1973 ◽  
Vol 31 ◽  
pp. 496-497
Author(s):  
J. J. Paulin
Keyword(s):  
Cell Membrane ◽  
Lateral Surface ◽  
The Body ◽  
Flagellar Pocket ◽  
Integral Component ◽  
Free Flagellum ◽  
Flagellar Axoneme

Movement in epimastigote and trypomastigote stages of trypanosomes is accomplished by planar sinusoidal beating of the anteriorly directed flagellum and associated undulating membrane. The flagellum emerges from a bottle-shaped depression, the flagellar pocket, opening on the lateral surface of the cell. The limiting cell membrane envelopes not only the body of the trypanosome but is continuous with and insheathes the flagellar axoneme forming the undulating membrane. In some species a paraxial rod parallels the axoneme from its point of emergence at the flagellar pocket and is an integral component of the undulating membrane. A portion of the flagellum may extend beyond the anterior apex of the cell as a free flagellum; the length is variable in different species of trypanosomes.

Trophoblast Cell Membrane Interactions at Implantation

1970 ◽  
Vol 28 ◽  
pp. 310-311
Author(s):  
A. C. Enders
Keyword(s):  
Epithelial Cells ◽  
Cell Membrane ◽  
Membrane Fusion ◽  
Trophoblast Cell ◽  
Membrane Interactions ◽  
Uterine Epithelial Cells ◽  
Functional Complex ◽  
Cytotrophoblast Cells ◽  
Complex Relationships ◽  
Syncytial Trophoblast

The alteration in membrane relationships seen at implantation include 1) interaction between cytotrophoblast cells to form syncytial trophoblast and addition to the syncytium by subsequent fusion of cytotrophoblast cells, 2) formation of a wide variety of functional complex relationships by trophoblast with uterine epithelial cells in the process of invasion of the endometrium, and 3) in the case of the rabbit, fusion of some uterine epithelial cells with the trophoblast.Formation of syncytium is apparently a membrane fusion phenomenon in which rapid confluence of cytoplasm often results in isolation of residual membrane within masses of syncytial trophoblast. Often the last areas of membrane to disappear are those including a desmosome where the cell membranes are apparently held apart from fusion.

Some Conditions Necessary for Pinocytosis

1968 ◽  
Vol 26 ◽  
pp. 142-143
Author(s):  
M. W. Brightman
Keyword(s):  
Smooth Muscle ◽  
Cell Membrane ◽  
Toxic Effects ◽  
Cytological Evidence ◽  
Cell Processes

The cytological evidence for pinocytosis is the focal infolding of the cell membrane to form surface pits that eventually pinch off and move into the cytoplasm. This activity, which can be inhibited by oxidative and glycolytic poisons, is performed only by cell processes that are at least 300A wide. However, the interpretation of such toxic effects becomes equivocal if the membrane invaginations do not normally lead to the formation of migratory vesicles, as in some endothelia and in smooth muscle. The present study is an attempt to set forth some conditions under which pinocytosis, as distinct from the mere inclusion of material in surface invaginations, can take place.

Electron microscopic radioautographic studies on the incorporation of 3H proline in the glomerular basement membrane (GBM) in antistreptococcal-cell-membrane (SCM) injected mice

1984 ◽  
Vol 42 ◽  
pp. 188-189
Author(s):  
R.P. Nayyar ◽  
C.F. Lange ◽  
J. L. Borke
Keyword(s):  
Body Weight ◽  
Cell Membrane ◽  
Basement Membrane ◽  
Glomerular Basement Membrane ◽  
Mesangial Matrix ◽  
Electron Microscopic ◽  
Group A ◽  
Injection Protocol

Streptococcal cell membrane (SCM) antiserum injected mice show a significant thickening of glomerular basement membrane (GBM) and an increase in mesangial matrix within 4 to 24 hours of antiserum administration (1,2,3). This study was undertaken to evaluate the incorporation of 3H proline into glomerular cells and GBM under normal and anti-SCM induced conditions. Mice were administered, intraperitoneally, 0.1 ml of normal or anti-SCM serum followed by a 10 µC/g body weight injection of 3H proline. Details of the preparation of anti-SCM (Group A type 12 streptococcal pyogenes) and other sera and injection protocol have been described elsewhere (2). After 15 minutes of isotope injection a chase of cold proline was given and animal sacrificed at 20 minutes, 1,2,4,8,24 and 48 hours. One of the removed kidneys was processed for immunofluorescence, light and electron microscopic radioautographic studies; second kidney was used for GBM isolation and aminoacid analysis.

High-voltage electron microscopy of patch-clamped membranes

1987 ◽  
Vol 45 ◽  
pp. 582-583
Author(s):  
F. Sachs ◽  
M. J. Song
Keyword(s):  
Electron Microscopy ◽  
Cell Membrane ◽  
Patch Clamp ◽  
High Voltage Electron Microscopy ◽  
Small Patch ◽  
Cellular Electrophysiology ◽  
Voltage Electron ◽  
Electron Microscopes ◽  
Patch Technique ◽  
Membrane Patch

Cellular electrophysiology has been revolutionized by the introduction of patch clamp techniques. The patch clamp records current from a small patch of the cell membrane which has been sucked into a glass pipette. The membrane patch, a few micons in diameter, is attached to the glass by a seal which is electrically, diffusionally and mechanically tight. Because of the tight electrical seal, the noise level is low enough to record the activity of single ion channels over a time scale extending from 10μs to days. However, although the patch technique is over ten years old, the patch structure is unknown. The patch is inside a glass pipette where it has been impossible to see with standard electron microscopes. We show here that at 1 Mev the glass pipette is transparent and the membrane within can be seen with a resolution of about 30 A.

Study on erythrocytes by SEM photogrammetry (SEMP) technique

1990 ◽  
Vol 48 (3) ◽  
pp. 724-725
Author(s):  
Tong Wensheng ◽  
Lu Lianhuang ◽  
Zhang Zhijun
Keyword(s):  
Quantitative Analysis ◽  
Cell Membrane ◽  
Clinical Diagnosis ◽  
Human Body ◽  
Blood Cells ◽  
Three Dimensional ◽  
Normal Person ◽  
Blood Disease ◽  
Computation Technique ◽  
Important Basis

This is a combined study of two diffirent branches, photogrammetry and morphology of blood cells. The three dimensional quantitative analysis of erythrocytes using SEMP technique, electron computation technique and photogrammetry theory has made it possible to push the study of mophology of blood cells from LM, TEM, SEM to a higher stage, that of SEM P. A new path has been broken for deeply study of morphology of blood cells.In medical view, the abnormality of the quality and quantity of erythrocytes is one of the important changes of blood disease. It shows the abnormal blood—making function of the human body. Therefore, the study of the change of shape on erythrocytes is the indispensable and important basis of reference in the clinical diagnosis and research of blood disease.The erythrocytes of one normal person, three PNH Patients and one AA patient were used in this experiment. This research determines the following items: Height;Length of two axes (long and short), ratio; Crevice in depth and width of cell membrane; Circumference of erythrocytes; Isoline map of erythrocytes; Section map of erythrocytes.

Sign in / Sign up

Export Citation Format

Share Document