scholarly journals Effects of CGA-N12 on the membrane structure of Candida tropicalis cells

2020 ◽  
Vol 477 (10) ◽  
pp. 1813-1825
Author(s):  
Ruifang Li ◽  
Weini Shi ◽  
Ruiling Zhang ◽  
Liang Huang ◽  
Yanjie Yi ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Candida Tropicalis ◽  
Membrane Structure ◽  
Chloride Ions ◽  
Fluorescent Dye ◽  
Potassium Ions ◽  
Membrane Channel ◽  
Channel Characteristics ◽  
Trisodium Salt ◽  
Fluidity Of Membranes

The antimicrobial peptide CGA-N12 (NH2-ALQGAKERAHQQ-COOH) is an active peptide derived from chromogranin A (CGA) and consists of the 65th to 76th amino acids of the N-terminus. The results of our previous studies showed that CGA-N12 exerts anti-Candida activity by inducing apoptosis without destroying the integrity of cell membranes. In this study, the effect of CGA-N12 on the cell membrane structure of Candida tropicalis was investigated. CGA-N12 resulted in the dissipation of the membrane potential, the increase in membrane fluidity, and the outflow of potassium ions in C. tropicalis without significantly changing the ergosterol level. Fluorescence quenching was applied to evaluate the membrane channel characteristics induced by CGA-N12 through detection of the following: membrane permeability of hydrated Cl− (ϕ ≈ 0.66 nm) using the membrane-impermeable halogen anion-selective fluorescent dye lucigenin, passage of the membrane-impermeable dye carboxyfluorescein (CF) (ϕ ≈ 1 nm) through the membrane, and membrane permeation of H3O+ based on the membrane non-permeable pH-sensitive fluorescent dye 8-hydroxypyrene-1,3,6-trisulfonic acid, trisodium salt (HPTS). In conclusion, CGA-N12 can induce the formation of non-selective ion channels <1 nm in diameter in the membranes of C. tropicalis, resulting in the leakage of potassium ions, chloride ions, and protons, among others, leading to dissipation of the membrane potential. As a result, the fluidity of membranes is increased without destroying the synthesis of ergosterol is not affected.

scholarly journals Electrical Characteristics and Activation Potential of Bufo Eggs

1959 ◽  
Vol 43 (1) ◽  
pp. 139-157 ◽  
Author(s):  
Takashi Maéno
Keyword(s):  
Membrane Potential ◽  
Action Potential ◽  
Membrane Resistance ◽  
Chloride Ions ◽  
Potassium Ions ◽  
Ionic Mechanism ◽  
Electrical Characteristics ◽  
Activation Potential ◽  
Specific Permeability ◽  
Toad Bufo

Electrical characteristics and their changes during activation were studied with the microelectrodes on the oocytes and eggs of the toad, Bufo vulgaris formosus Boulenger. In young oocytes, the membrane characteristics had some similarities to those of nerve and muscle, except for a relatively large resistance of 25 KΩcm.2 and an absence of the action potential in the former. After maturation, however, the membrane characteristics became entirely different from those of oocytes and other excitable tissues. In the mature eggs the membrane resistance was measured to be as high as 200 KΩcm.2, and no specific permeability of the membrane to potassium ions was observable. A slow monophasic change in the membrane potential was recorded in every activation produced by mechanical stimulation, and termed "activation potential." In fresh water, its amplitude was as large as 80 to 90 mv. with an overshoot of about 50 mv. The activation potential might be comparable to the action potential of nerve and muscle, but was fundamentally different in ionic mechanism from the latter, since the former was caused by a marked increase in permeability to chloride ions.

Ground water quality of selected areas of Punjab and Sind Provinces, Pakistan: Chemical and microbiological aspects

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Ionic Concentration ◽  
Chloride Ions ◽  
Potassium Ions ◽  
Ammonium Ions ◽  
High Concentration ◽  
Phosphate Ions ◽  
Sodium Magnesium ◽  
Very High ◽  
Microbiological Aspects

The assessment of groundwater is essential for the estimation of suitability of water for safe use. An attempt has been made to study the groundwater of selected areas of Punjab (Sheikhupura & Sahiwal) and Sindh (Sindh, Jawar Dharki and Dharki), Pakistan. The results indicate that pH, color and odor were all within limits of WHO that is pH ranges 6.5–8.5, colorless and odorless, respectively. The high values of suspended solids were observed in the Sindh-1 and Dharki samples. Microbiologically only Sahiwal and Jawar Dharki were found fit for drinking purpose. Trace metals analysis of Sheikhupura-1 and Sindh-1 showed that values do not fall within limits of WHO for Iron. The ionic concentration analysis showed that high bicarbonate (HCO3-), ions are present in the samples of Sahiwal and Dharki; Sindh-1 and Jawar Dharki samples showed very high concentration for chloride ions, all samples were satisfactory level for sulphate (SO42-), sodium, magnesium and phosphate ions except samples of Sindh-1 and Jawar Dharki. High concentration of calcium and potassium ions was observed in samples of Sindh-1, while all other samples were found fit for drinking purposes in respect of nitrate, nitrite and ammonium ions. The high concentration of Fluoride was found only in Sheikhupura-2 samples.

Evidence for the role of a Na(+)/HCO(3)(−) cotransporter in trout hepatocyte pHi regulation

2000 ◽  
Vol 203 (14) ◽  
pp. 2201-2208 ◽  
Author(s):  
M. Furimsky ◽  
T.W. Moon ◽  
S.F. Perry
Keyword(s):  
Membrane Potential ◽  
Anion Transport ◽  
Fluorescent Dye ◽  
Proton Extrusion ◽  
Pharmacological Agents ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Trout Hepatocyte ◽  
Acid Loading ◽  
Na Uptake ◽  
Phi Regulation

The mechanisms of intracellular pH (pHi) regulation were examined in hepatocytes of the rainbow trout Oncorhynchus mykiss. pHi was monitored using the pH-sensitive fluorescent dye BCECF, and the effects of various media and pharmacological agents were examined for their influence on baseline pHi and recovery rates from acid and base loading. Rates of Na(+) uptake were measured using (22)Na, and changes in membrane potential were examined using the potentiometric fluorescent dye Oxonol VI. The rate of proton extrusion following acid loading was diminished by the blockade of either Na(+)/H(+) exchange (using amiloride) or anion transport (using DIDS). The removal of external HCO(3)(−) and the abolition of outward K(+) diffusion by the channel blocker Ba(2+) also decreased the rate of proton extrusion following acid load. Depolarization of the cell membrane with 50 mmol l(−)(1) K(+), however, did not affect pHi. The rate of recovery from base loading was significantly diminished by the blockade of anion transport, removal of external HCO(3)(−) and, to a lesser extent, by blocking Na(+)/H(+) exchange. The blockade of K(+) conductance had no effect. The decrease in Na(+) uptake rate observed in the presence of the anion transport blocker DIDS and the DIDS-sensitive hyperpolarization of membrane potential during recovery from acid loading suggest that a Na(+)-dependent electrogenic transport system is involved in the restoration of pHi after intracellular acidification. The effects on baseline pHi indicate that the different membrane exchangers are tonically active in the maintenance of steady-state pHi. This study confirms the roles of a Na(+)/H(+) exchanger and a Cl(−)/HCO(3)(−) exchanger in the regulation of trout hepatocyte pHi and provides new evidence that a Na(+)/HCO(3)(−) cotransporter contributes to pHi regulation.

scholarly journals Reduction in the mitochondrial membrane potential of Toxoplasma gondii after invasion of host cells

1984 ◽  
Vol 70 (1) ◽  
pp. 73-81
Author(s):  
K. Tanabe ◽  
K. Murakami
Keyword(s):  
Membrane Potential ◽  
Toxoplasma Gondii ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Protozoan Parasite ◽  
Fluorescent Dye ◽  
Host Cells ◽  
Intracellular Parasites ◽  
Neutral Compounds ◽  
Infected Cells

The membrane potential of Toxoplasma gondii, an obligatory intracellular protozoan parasite, was monitored with the cationic permeant fluorescent dye rhodamine 123 (R123). Fluorescence microscopy revealed R123 to be partitioned predominantly in a restricted part of the parasite, which consisted of twisted or branched tubules, or of granular bodies. These structures were frequently connected to each other. The dye retention by these structures was markedly reduced by treating R123-labelled parasites with the proton ionophore, carbonylcyanide m-chlorophenylhydrazone, the potassium ionophore, valinomycin and the inhibitor of electron transport, antimycin A. Thus, these structures are regarded as the parasite mitochondria. Another cationic fluorescent dye, rhodamine 6G, stained the parasite mitochondria, whereas a negatively charged fluorescent dye, fluorescein, and the neutral compounds, rhodamine 110 and rhodamine B, did not. This fact indicates that R123 monitored the parasite mitochondrial membrane potential. T. gondii-infected 3T3 cells were also stained with R123. In contrast to the mitochondria of extracellular parasites, those of intracellular parasites failed to take up the dye. The absence of fluorescence in intracellular parasites persisted until the infected host cells ruptured and liberated daughter parasites 1 day after infection. Parasites, liberated from the host cells, either spontaneously or artificially by passing the infected cells through a 27G needle, regained the ability to take up the dye. After direct microinjection of R123 into the vacuole in which the parasite grows and multiples, the dye appeared in the host-cell mitochondria but not in the parasite's mitochondria. Thus, we conclude that the mitochondrial membrane potential of T. gondii was reduced after invasion of host cells by the parasite.

scholarly journals Biochemical and Molecular Studies on the Role of Rosemary (Rosmarinus officinalis) Extract in Reducing Liver and Kidney Toxicity Due to Etoposide in Male Rats

2019 ◽  
pp. 1-11
Author(s):  
Majd Almakhatreh ◽  
Ezar Hafez ◽  
Ehab Tousson ◽  
Ahmed Masoud
Keyword(s):  
Dna Damage ◽  
Calcium Ions ◽  
Chloride Ions ◽  
Male Rats ◽  
Control Group ◽  
Potassium Ions ◽  
Sodium Ions ◽  
Total Proteins ◽  
Kidney Toxicity ◽  
Liver And Kidney

Aims: Etoposide (Vepesid) is chemotherapeutic drugs that inhibit topoisomerase II activity and long been used for treatment of human malignancies, where it is a semi-synthetic compound derived from the plant Podophyllum peltatum. The current study was designed to investigate the possible protective effect of rosemary extract against Etoposide -induced changes in liver and kidney functions, and DNA damage in rats. Materials and Methods: A total of 50 male Wistar albino rats were divided randomly into four groups (1st group was control; 2nd group was treated with rosemary, 3rd group was received etoposide, and 4th & 5th groups was co- and post treated groups respectively). Results: The administration of Etoposide revealed a significant increase in serum ALT, AST, ALP, creatinine, urea, potassium ions, chloride ions, and DNA damage. In contrast; a significant decrease in albumen, total proteins, sodium ions, and calcium ions were when compared with control group. This increased in ALT, AST, ALP, creatinine, urea, potassium ions, chloride ions, and DNA damage was reduced after administration of rosemary when co-treated with etoposide (G4), or post-treated after etoposide  (G5) for four weeks with lowest damage in G4. Also, this decreased in albumen, total proteins, sodium ions, and calcium ions was increased after administration of rosemary when co-treated with etoposide (G4), or post-treated after etoposide (G5) for four weeks with lowest damage in G4. Conclusion: It could be concluded that rosemary has a promising role and it worth to be considered as a natural substance for protective the liver and kidney toxicity induced by etoposide (Vepesid) chemotherapy.

Effects of glycine and GABA on bulbar respiratory neurons of cat

1990 ◽  
Vol 63 (5) ◽  
pp. 955-965 ◽  
Author(s):  
A. Haji ◽  
J. E. Remmers ◽  
C. Connelly ◽  
R. Takeda
Keyword(s):  
Membrane Potential ◽  
Amino Acid ◽  
Input Resistance ◽  
Postsynaptic Membrane ◽  
Chloride Ions ◽  
Membrane Receptors ◽  
Membrane Properties ◽  
Respiratory Neurons ◽  
Gaba Uptake ◽  
Gamma Aminobutyric Acid

1. Bulbar respiratory neurons of unanesthetized, decerebrate cats were impaled with the center pipette of a compound, coaxial microelectrode. This electrode allowed intracellular recording of membrane potential (MP) through the central pipette and extracellular iontophoresis of glycine or gamma-aminobutyric acid (GABA) from micropipettes encircling the center pipette with their tips recessed 20-40 microns from the tip of the center pipette. 2. Seventy-seven studies were carried out on 32 inspiratory and 28 postinspiratory neurons with the use of brief pulses (0.3-0.5 s) or long pulses (3-10 s) spanning one or more respiratory cycles. In both neuronal types, GABA and glycine decreased spike frequency, synaptic "noise," respiratory fluctuations of MP, and "input" resistance in a dose-related fashion. 3. In most cases, the membrane was hyperpolarized by the amino acid. The reverse response (depolarization) was observed when the membrane had been hyperpolarized by current clamp. This reversal from hyperpolarization to depolarization occurred at a MP of -81 +/- 2.3 mV (mean +/- SE, n = 7) for glycine and -81 +/- 1.6 (n = 6) for GABA. 4. After intracellular iontophoresis of chloride ions, application of GABA and glycine depolarized the membrane. 5. During relatively long (3-10 s) periods of iontophoresis of glycine or GABA, the effects on MP and input resistance waned. In some cases (23%), the amino acid depolarized the membrane at the most hyperpolarizated portion of the MP trajectory. This was never observed with brief iontophoretic pulses. Such effects of long duration iontophoresis may reflect changes in membrane properties secondary to the primary action of the amino acid on the membrane of the impaled neuron or indirect synaptic actions via changes in discharge of neighboring neurons. 6. Extracellular iontophoresis of a GABA uptake inhibitor, nipecotic acid, potentiated the effects of GABA. 7. Extracellular application of tetrodotoxin appeared to act pre- and postsynaptically to reduce respiratory fluctuations in membrane potential and to increase input resistance without altering the effects of iontophoresed glycine and GABA, suggesting that the amino acids act on postsynaptic membrane receptors not linked to fast sodium channels.(ABSTRACT TRUNCATED AT 400 WORDS)

Central modulation of stretch receptor neurons during fictive locomotion in lamprey

1996 ◽  
Vol 76 (2) ◽  
pp. 1224-1235 ◽  
Author(s):  
L. Vinay ◽  
J. Y. Barthe ◽  
S. Grillner
Keyword(s):  
Spinal Cord ◽  
Membrane Potential ◽  
Receptor Antagonist ◽  
Chloride Ions ◽  
Stretch Receptor ◽  
Fictive Locomotion ◽  
Gamma Aminobutyric Acid ◽  
Potential Oscillations ◽  
Receptor Neurons ◽  
Membrane Potential Oscillations

1. In lamprey, stretch receptor neurons (SRNs), also referred to as edge cells, are located along the lateral margin of the spinal cord. They sense the lateral movements occurring in each swim cycle during locomotion. The isolated lamprey spinal cord in vitro was used to investigate the activity of SRNs during fictive locomotion induced by bath-applied N-methyl-D-aspartate (NMDA). Intracellular recordings with potassium acetate filled electrodes showed that 63% of SRNs had a clear locomotor-related modulation of their membrane potential. 2. Of the modulated SRNs, two-thirds had periods of alternating excitation and inhibition occurring during the ipsilateral and the contralateral ventral root bursts, respectively. The phasic hyperpolarization could be reversed into a depolarizing phase after the injection of chloride ions into the cells; this revealed a chloride-dependent synaptic drive. The remaining modulated SRNs were inhibited phasically during ipsilateral motor activity. 3. Experiments with barriers partitioning the recording chamber with the spinal cord into three pools, allowed an inactivation of the locomotor networks within one pool by washing out NMDA from the pool in which the SRN was recorded. This resulted in a marked reduction, but not an abolishment, of the amplitude of the membrane potential oscillations. Both the excitatory and the inhibitory phases were reduced, resulting from removal of input from inhibitory and excitatory interneurons projecting from the adjacent pools. If the glycine receptor antagonist strychnine (1 microM) was applied in one pool, the phasic hyperpolarizing phase disappeared without affecting the excitatory phase. 4. Bath application of the gamma-aminobutyric acid (GABA)A receptor antagonist, bicuculline (50-100 microM) blocked the spontaneous large unitary inhibitory postsynaptic potentials, which occurred without a clear phasic pattern. Bicuculline had no significant effect on the peak to peak amplitude of the locomotor-related membrane potential oscillations. The inhibition in SRNs therefore has a dual origin: glycinergic interneurons provide phasic inhibition, while the GABA system can exert a tonic inhibition via GABAA receptors. 5. These data show that, in addition to the stretch-evoked excitation, which SRNs receive during each locomotor cycle, most of them also receive excitation from the central pattern generator network during the ipsilateral contraction, which may ensure a maintained high level of sensitivity to stretch during the shortening phase of the locomotor cycle. This arrangement is analogous to the efferent control of muscle spindles exerted by gamma-motoneurons in mammals, which as a rule are coactivated with alpha-motoneurons to the same muscle (alpha-gamma linkage).

scholarly journals Dilation of the influenza hemagglutinin fusion pore revealed by the kinetics of individual cell-cell fusion events.

1996 ◽  
Vol 135 (1) ◽  
pp. 63-71 ◽  
Author(s):  
R Blumenthal ◽  
D P Sarkar ◽  
S Durell ◽  
D E Howard ◽  
S J Morris
Keyword(s):  
Membrane Potential ◽  
Cell Fusion ◽  
Individual Cell ◽  
Fluorescent Dye ◽  
Fusion Pore ◽  
Influenza Hemagglutinin ◽  
Rbc Membrane ◽  
Pore Opening ◽  
Kinetics Of ◽  
Fluorescent Lipid

We have monitored kinetics of fusion between cell pairs consisting of a single influenza hemaglutinin (HA)-expressing cell and a single erythrocyte (RBC) that had been labeled with both a fluorescent lipid (Dil) in the membrane and a fluorescent solute (calcein) in the aqueous space. Initial fusion pore opening between the RBC and HA-expressing cell produced a change in RBC membrane potential (delta psi) that was monitored by a decrease in Dil fluorescence. This event was followed by two distinct stages of fusion pore dilation: the flux of fluorescent lipid (phi L) and the flux of a large aqueous fluorescent dye (phi s). We have analyzed the kinetics of events that occur as a result of transitions between a fusion pore (FP) and a solute permissive fusion pore (FPs). Our data are consistent with a fusion pore comprising six HA trimers.

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