scholarly journals An All-or-None Response in the Release of Potassium by Yeast Cells Treated with Methylene Blue and Other Basic Redox Dyes

1959 ◽  
Vol 43 (1) ◽  
pp. 97-107 ◽  
Author(s):  
Hermann Passow ◽  
Aser Rothstein ◽  
Barbara Loewenstein
Keyword(s):  
Methylene Blue ◽  
Cell Membrane ◽  
Threshold Level ◽  
Yeast Cells ◽  
Monovalent Cations ◽  
Membrane Breakdown ◽  
Percentage Loss ◽  
Bivalent Cations ◽  
Basic Dyes ◽  
Maximal Loss

Basic redox dyes, such as methylene blue, induce a loss of K+ from yeast cells. The maximal loss, rather than the rate of loss, is related to the dye concentration, the response following a normal distribution on a plot of log-dose, versus percentage loss of K+. This fact taken together with the observed correlation between K+ loss and frequency of staining (as measured by microscopic observation), indicates that the response is all-or-none for individual cells. The response is produced by all the basic redox dyes tested (9), but by none of the acidic dyes (4). However, only the oxidized form of the dye is effective. Cations protect the cells from the basic dyes in a competitive manner, the bivalent cations (especially UO2++) being more effective than monovalent cations. It is suggested that the action of the dyes involves two steps, the first a binding to ribonucleic acid in the cell membrane (with competition from cations) and the second, an oxidation of neighboring sulfhydryl groups to the disulfide form. At a threshold level, unique for each cell, a generalized membrane breakdown occurs, resulting in the release of potassium and of other cytoplasmic constituents.

scholarly journals Mechanosensitivity of cell membrane may govern creep-strain recovery, osmotic expansion and lysis.

2009 ◽  
Vol 56 (3) ◽  
Author(s):  
Piotr H Pawłowski
Keyword(s):  
Cell Membrane ◽  
Short Time Scale ◽  
Membrane Area ◽  
Membrane Breakdown ◽  
Simple Theoretical Model ◽  
Stressed Cell ◽  
Membrane Stretching ◽  
Short Time ◽  
Kinetics Of ◽  
Small Solute

A simple theoretical model considering cell membrane mechanosensitivity can accurately describe published experimental data on membrane area creeping and recovery, and on osmotic expansion and rupture. The model to data fit reveals real values of membrane tension and elasticity modulus, and the parameters describing membrane organization and kinetics of mechanosensitive membrane traffic, including small solute transport, water permeability, endocytosis, exocytosis, and caveolae formation. This estimation allows for separation and quantitative analysis of the participation of different processes constituting the response of plasmalemma to short time-scale membrane load. The predicted properties of the model were verified for membrane stretching at different osmotic pressures. Finally, a simple hypothesis concerning stressed cell membrane breakdown is postulated.

Experimental Study on the Adsorption of MB on Novel Photocatalyst Yeast/ZnS Hybrid Microspheres

2014 ◽  
Vol 924 ◽  
pp. 129-133
Author(s):  
Hai Gang Gou ◽  
Wei Sheng Guan ◽  
Li Yang ◽  
Zhao Qi Wang ◽  
Yang Zhi Zhu
Keyword(s):  
Experimental Study ◽  
Methylene Blue ◽  
Adsorption Capacity ◽  
Experimental Results ◽  
Yeast Cells ◽  
Isotherm Modeling ◽  
Adsorption Performance

Employing yeast cells as carriers,a novel cell-loaded photocatalyst yeast/ZnS (YC/ZnS) was successfully synthesized. The adsorption performance of methylene blue on the YC/ZnS microspheres was studied. Experimental results showed that the optimized adsorption conditions were 23°C,pH7 and the YC/ZnS dosage 4.5g/L. Under these conditions,the adsorption capacity of YC/ZnS could reach 471.2μg/g. Isotherm modeling revealed that Freundlich equations described well the adsorption of methylene blue onto YC/ZnS.

Modeling and Characterization of a Chemomechanical Actuator Based on Protein Transporters

2007 ◽  
Author(s):  
Vishnu Baba Sundaresan ◽  
Donald J. Leo
Keyword(s):  
Cell Membrane ◽  
Cell Membranes ◽  
Fluid Transport ◽  
Sucrose Concentration ◽  
Yeast Cells ◽  
Facilitated Diffusion ◽  
Flux Rate ◽  
Artificial Membrane ◽  
Saturation Concentration ◽  
Protein Transporters

Plants and animal cells are naturally occurring actuators that exhibit force and motion driven by fluid transport through the cell membrane. The protein transporters embedded in the cell membrane serve as the selective gateway for ion and fluid transport. The actuator presented in this work generates force and deformation from mass transport through an artificial membrane with protein transporters extracted from plant cell membranes. The artificial membrane is formed from purified 1-Palmitoyl-2-Oleoyl-sn-Glycero-3-[Phospho-L-Serine] (Sodium Salt) (POPS), 1-Palmitoyl-2-Oleoyl-sn-Glycero-3-Phosphoethanolamine (POPE) lipids and supported on a porous substrate. The protein transporter used in the actuator membrane is a proton-sucrose cotransporter, SUT4, extracted from yeast cells that genetically modified to grow the cotransporter in their cell membranes. The SUT4 transporter conducts proton and sucrose from the side of the membrane with higher concentration and carries water molecules across the membrane. It is observed from transport characterization experiments that fluid flux through the membrane varies with the applied sucrose concentration and hence is chosen as the control stimulus in the actuator. A modified four-state facilitated diffusion model is applied to the transport characterization data to compute the two characteristic parameters for fluid transport, saturation concentration and translocation rate, through the membrane. The flux rate through the membrane is observed to increase with the concentration till a particular value and saturates at a higher concentration. The concentration at which the flux rate through the membrane saturates is referred to as the saturation concentration. The saturation concentration for the actuator is experimentally found to be 6±0.6mM sucrose on the side with lower pH. The corresponding maximum translocation rate is found to be 9.6±1.2 nl/μ.cm2.min. The maximum steady state deformation produced by the actuator is observed at 30 mM sucrose that corresponds to a force of 0.89 mN.

scholarly journals Antifungal activity of the clove essential oil from Syzygium aromaticum on Candida, Aspergillus and dermatophyte species

2009 ◽  
Vol 58 (11) ◽  
pp. 1454-1462 ◽  
Author(s):  
Eugénia Pinto ◽  
Luís Vale-Silva ◽  
Carlos Cavaleiro ◽  
Lígia Salgueiro
Keyword(s):  
Antifungal Activity ◽  
Essential Oil ◽  
Cell Membrane ◽  
Fungal Infections ◽  
Yeast Cells ◽  
Syzygium Aromaticum ◽  
Clove Oil ◽  
Fungal Cell ◽  
Minimum Fungicidal Concentration ◽  
Clove Essential Oil

The composition and antifungal activity of clove essential oil (EO), obtained from Syzygium aromaticum, were studied. Clove oil was obtained commercially and analysed by GC and GC-MS. The EO analysed showed a high content of eugenol (85.3 %). MICs, determined according to Clinical and Laboratory Standards Institute protocols, and minimum fungicidal concentration were used to evaluate the antifungal activity of the clove oil and its main component, eugenol, against Candida, Aspergillus and dermatophyte clinical and American Type Culture Collection strains. The EO and eugenol showed inhibitory activity against all the tested strains. To clarify its mechanism of action on yeasts and filamentous fungi, flow cytometric and inhibition of ergosterol synthesis studies were performed. Propidium iodide rapidly penetrated the majority of the yeast cells when the cells were treated with concentrations just over the MICs, meaning that the fungicidal effect resulted from an extensive lesion of the cell membrane. Clove oil and eugenol also caused a considerable reduction in the quantity of ergosterol, a specific fungal cell membrane component. Germ tube formation by Candida albicans was completely or almost completely inhibited by oil and eugenol concentrations below the MIC values. The present study indicates that clove oil and eugenol have considerable antifungal activity against clinically relevant fungi, including fluconazole-resistant strains, deserving further investigation for clinical application in the treatment of fungal infections.

Removal of Basic Dyes (Rhodamine B and Methylene Blue) from Aqueous Solutions Using Bagasse Fly Ash

2000 ◽  
Vol 35 (13) ◽  
pp. 2097-2113 ◽  
Author(s):  
VINOD K. GUPTA ◽  
DINESH MOHAN ◽  
SAURABH SHARMA ◽  
MONICA SHARMA
Keyword(s):  
Methylene Blue ◽  
Fly Ash ◽  
Aqueous Solutions ◽  
Rhodamine B ◽  
Bagasse Fly Ash ◽  
Basic Dyes

Sodium permeability and myocardial resistance to cell swelling during metabolic blockade

1980 ◽  
Vol 239 (1) ◽  
pp. H31-H39 ◽  
Author(s):  
M. B. Pine ◽  
D. Kahne ◽  
B. Jaski ◽  
C. S. Apstein ◽  
K. Thorp ◽  
...  
Keyword(s):  
Cell Membrane ◽  
Membrane Permeability ◽  
Renal Cortex ◽  
Cell Volume Regulation ◽  
Cell Membrane Permeability ◽  
Cell Swelling ◽  
Monovalent Cations ◽  
Sodium Potassium ◽  
Produce Cell ◽  
Potassium Exchange

The role of cell membrane permeability to sodium in cell volume regulation during inhibition of the sodium-potassium exchange pump with ouabain and during total metabolic blockade was evaluated in sections of guinea pig renal cortex, ventricle, and atrium incubated in Krebs-Henseleit solution. In all tissues, 2 and 3 h of ouabain and metabolic blockade resulted in similar marked losses of potassium and parallel continuous reductions in resting membrane potentials. Only metabolic blockade of renal cortex increased cell water, chloride, and total monovalent cations (potassium plus sodium) significantly. Compared to ouabain, metabolic blockade markedly increased the rate of cellular washout of 24Na+ from renal cortex (t 1/2 reduced by 47%), which was significantly greater than reductions in t 1/2 from ventricle (16%) and atrium (15%). Thus, inhibition of sodium-potassium exchange pump activity was not sufficient to produce cell swelling unless associated with marked increases in cell membrane permeability to sodium, in which case sodium influx exceeded potassium loss and substantial increases in monovalent cations, chloride, and water occurred.

Cell-Glass Separation Depends on Salt Concentration and Valency: Measurements on Dictyostelium Amoebae by Finite Aperture Interferometry

1982 ◽  
Vol 54 (1) ◽  
pp. 299-310
Author(s):  
DAVID GINGELL ◽  
SHEILA VINCE
Keyword(s):  
Ionic Strength ◽  
Cell Membrane ◽  
Divalent Cations ◽  
Optical Measurements ◽  
Surface Glycoprotein ◽  
Monovalent Cations ◽  
Cell Surface Glycoprotein ◽  
Cellular Slime ◽  
Finite Aperture ◽  
Interacting Surfaces

Using pre-aggregation amoebae of the cellular slime mould Dictyostelium discoideum we have investigated the influence of cation concentration and valency on cell-glass separation. For computing the separation we used interference reflection microscopy and converted measured image irradiance to distance by finite aperture theory. Alterations in ionic strength caused virtually instantaneous reversible changes in the interference image due to changes in cell membrane-glass separation. In solutions containing monovalent cations, a change in ionic strength from 20 mM to 0.5 mM increased the separation of the plasmalemma from the glass by 60 nm. Divalent cations were better than monovalent cations at maintaining a small separation. Our results show that both divalent and trivalent cations adsorb to one or both of the interacting surfaces, in addition to acting as electrostatic double-layer counterions. The optical measurements also show that the cell membrane-glass gap is not reduced to zero by counterion screening; this is apparently due to the presence of a cell surface glycoprotein coat.

scholarly journals A conserved tryptophan in pneumolysin is a determinant of the characteristics of channels formed by pneumolysin in cells and planar lipid bilayers

1998 ◽  
Vol 329 (3) ◽  
pp. 571-577 ◽  
Author(s):  
E. Yuri KORCHEV ◽  
C. Lindsay BASHFORD ◽  
Cecilia PEDERZOLLI ◽  
A. Charles PASTERNAK ◽  
J. Peter MORGAN ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Cell Membrane ◽  
Molecular Mass ◽  
Lipid Bilayers ◽  
Planar Lipid Bilayers ◽  
Wild Type ◽  
Bivalent Cations ◽  
Ring Structures ◽  
Ion Conducting ◽  
Small Channels

Pneumolysin is one of the family of thiol-activatable, cytolytic toxins. Within these toxins the amino acid sequence Trp-Glu-Trp-Trp is conserved. Mutations made in this region of pneumolysin, residues 433-436 inclusive, did not affect cell binding or the formation of toxin oligomers in the target cell membrane. However, the mutations did affect haemolysis, leakage of low-molecular-mass metabolites from Lettre cells and the induction of conductance channels across planar lipid bilayers. Of eight modified pneumolysins examined, Trp-433 → Phe showed the smallest amount of haemolysis or leakage (less than 5% of wild type). Pneumolysin-induced leakage from Lettre cells was sensitive to inhibition by bivalent cations but the extent of inhibition varied depending on the modification. Leakage by the mutant Trp-433 → Phe was least sensitive to cation inhibition. The ion-conducting channels formed across planar lipid bilayers exhibit small (less than 30 pS), medium (30 pS-1 nS) and large (more than 1 nS) conductance steps. Small- and medium-sized channels were preferentially closed by bivalent cations. In contrast with wild-type toxin, which formed predominantly small channels, the modified toxin Trp-433 → Phe formed large channels that were insensitive to cation-induced closure. Polysaccharides of molecular mass more than 15 kDa inhibited haemolysis by wild-type toxin, but polysaccharide of up to 40 kDa did not prevent haemolysis by Trp-433 → Phe. Electron microscopy revealed that Trp-433 → Phe formed oligomeric arc and ring structures with dimensions identical with those of wild-type toxin, and that the ratio of arcs to rings formed was the same for wild-type toxin and the Trp-433 → Phe variant. We conclude that the change Trp-433 → Phe affects channel formation at a point subsequent to binding to the cell membrane and the formation of oligomers, and that the size of arc and ring structures revealed by electron microscopy does not reflect the functional state of the channels.

scholarly journals Evidence for a Role for the Plasma Membrane in the Nanomechanical Properties of the Cell Wall as Revealed by an Atomic Force Microscopy Study of the Response of Saccharomyces cerevisiae to Ethanol Stress

2016 ◽  
Vol 82 (15) ◽  
pp. 4789-4801 ◽  
Author(s):  
Marion Schiavone ◽  
Cécile Formosa-Dague ◽  
Carolina Elsztein ◽  
Marie-Ange Teste ◽  
Helene Martin-Yken ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Atomic Force Microscopy ◽  
Cell Wall ◽  
Cell Membrane ◽  
Yeast Cells ◽  
Ethanol Stress ◽  
Wild Type ◽  
Force Microscopy ◽  
Nanomechanical Properties ◽  
Atomic Force

ABSTRACTA wealth of biochemical and molecular data have been reported regarding ethanol toxicity in the yeastSaccharomyces cerevisiae. However, direct physical data on the effects of ethanol stress on yeast cells are almost nonexistent. This lack of information can now be addressed by using atomic force microscopy (AFM) technology. In this report, we show that the stiffness of glucose-grown yeast cells challenged with 9% (vol/vol) ethanol for 5 h was dramatically reduced, as shown by a 5-fold drop of Young's modulus. Quite unexpectedly, a mutant deficient in the Msn2/Msn4 transcription factor, which is known to mediate the ethanol stress response, exhibited a low level of stiffness similar to that of ethanol-treated wild-type cells. Reciprocally, the stiffness of yeast cells overexpressingMSN2was about 35% higher than that of the wild type but was nevertheless reduced 3- to 4-fold upon exposure to ethanol. Based on these and other data presented herein, we postulated that the effect of ethanol on cell stiffness may not be mediated through Msn2/Msn4, even though this transcription factor appears to be a determinant in the nanomechanical properties of the cell wall. On the other hand, we found that as with ethanol, the treatment of yeast with the antifungal amphotericin B caused a significant reduction of cell wall stiffness. Since both this drug and ethanol are known to alter, albeit by different means, the fluidity and structure of the plasma membrane, these data led to the proposition that the cell membrane contributes to the biophysical properties of yeast cells.IMPORTANCEEthanol is the main product of yeast fermentation but is also a toxic compound for this process. Understanding the mechanism of this toxicity is of great importance for industrial applications. While most research has focused on genomic studies of ethanol tolerance, we investigated the effects of ethanol at the biophysical level and found that ethanol causes a strong reduction of the cell wall rigidity (or stiffness). We ascribed this effect to the action of ethanol perturbing the cell membrane integrity and hence proposed that the cell membrane contributes to the cell wall nanomechanical properties.

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