Proton Motive Potential Difference Across the Plasma Membrane of Plant Cells: a Comparison of Cultured Cells and Protoplasts From Italian Ryegrass (Lolium multiflorum Lam.) Endosperm

1984 ◽  
Vol 11 (3) ◽  
pp. 119 ◽  
Author(s):  
RJ Henry ◽  
A Schibeci ◽  
BA Stone
Keyword(s):  
Plasma Membranes ◽  
Cultured Cells ◽  
Lolium Multiflorum ◽  
Electrical Potential ◽  
Italian Ryegrass ◽  
Ph Gradient ◽  
Cytoplasmic Ph ◽  
Transmembrane Electrical Potential ◽  
Main Component ◽  
External Ph

The electrochemical proton gradient (ΔμH+) was measured across the plasma membranes of ryegrass (Lolium multiflorum Lam.) endosperm cells grown in suspension culture. The pH gradient (ΔpH) and the transmembrane electrical potential (ΔΨ) of cells and protoplasts were compared. The pH gradient (ΔpH) was measured from the distribution of acetylsalicylic acid and 5,5-dimethyloxazolidine and the membrane potential (ΔΨ) was calculated from the distribution of the lipophilic tetraphenylphosphonium cation (TPP+) between the cells and medium. The protoplasts and cells maintained a similar ΔpH. At the external pH of the growth medium (pH 5.5), the cytoplasmic pH was about 7. Under these conditions the ΔΨ was -60 mV (negative inside) for cells and -46 mV for protoplasts. ΔpH and ΔΨ have values which vary reciprocally depending on the external pH. The main contributor to ΔμH+ at pH 4.0 is ΔpH whereas, at pH 7.0, ΔΨ is the main component. The external K+ concentration influences the cytoplasmic pH significantly only at the higher external pH values.

scholarly journals Transmembrane electrical potential and transmembrane pH gradient in the acidophile Thiobacillus ferro-oxidans

1979 ◽  
Vol 178 (1) ◽  
pp. 195-200 ◽  
Author(s):  
J C Cox ◽  
D G Nicholls ◽  
W J Ingledew
Keyword(s):  
Membrane Potential ◽  
Intracellular Ph ◽  
Co2 Fixation ◽  
Electrical Potential ◽  
Sole Source ◽  
Ph Gradient ◽  
Electrochemical Gradient ◽  
Transmembrane Electrical Potential ◽  
External Ph

Thiobacillus ferro-oxidans is capable of using the oxidation of Fe2+ by O2 at pH 2.0 as the sole source of energy for growth and CO2 fixation. The bacterium maintains an intracellular pH of 6.5 over a range of external pH from 1.0 to 8.0, as measured by [14C]acetate and [3H]methylamine distribution. The membrane potential was estimated by the distribution of the lipid-soluble cation dibenzyldimethylammonium and the anion SCN-. At pH 2.0 (the pH of growth) during Fe2+ oxidation the transmembrane pH gradient is 4.5 units with an opposing membrane potential of -10mV, giving a proton electrochemical gradient of +256mV. This gradient is actively maintained.

scholarly journals Localization of β-glucan synthases on the membranes of cultured Lolium multiflorum (ryegrass) endosperm cells

1983 ◽  
Vol 209 (3) ◽  
pp. 627-633 ◽  
Author(s):  
R J Henry ◽  
A Schibeci ◽  
B A Stone
Keyword(s):  
Density Gradient ◽  
Plasma Membranes ◽  
Lolium Multiflorum ◽  
Sucrose Density Gradient ◽  
Italian Ryegrass ◽  
Beta Glucan ◽  
Glucan Synthase ◽  
Intracellular Membranes

The distribution of beta-glucan synthases between plasma membranes and intracellular membranes of suspension-cultured Italian-ryegrass (Lolium multiflorum Lam.) endosperm cells was examined. Highly purified plasma membranes prepared from protoplasts were only slightly enriched in beta-glucan synthases assayed at 10 microM- and 1 mM-UDP-glucose. Most beta-glucan synthase was associated with intracellular membranes. These membranes were fractionated on a linear sucrose density gradient and were resolved into different membrane fractions containing beta-glucan synthases. Beta-Glucan synthases assayed at 10 microM-UDP-glucose were found in a fraction banding at a density of 1.11 g . cm-3, but most of the beta-glucan synthase assayed at 1 mM-DDP-glucose was at a density of 1.04 g . cm-3.

Estimation of cellular pH gradients with 31P-NMR in intact rabbit renal tubular cells

1984 ◽  
Vol 247 (3) ◽  
pp. C188-C196 ◽  
Author(s):  
S. Adler ◽  
E. Shoubridge ◽  
G. K. Radda
Keyword(s):  
Ph Gradient ◽  
Cytoplasmic Ph ◽  
Buffer Solution ◽  
Ph Gradients ◽  
Tubular Cells ◽  
Renal Tubular Cells ◽  
Ph Values ◽  
Intact Rabbit ◽  
Renal Tubular ◽  
External Ph

To determine intracellular pH gradients rabbit renal cortical tubular cells were prepared by collagenase separation, suspended in a Krebs-Ringer buffer solution, and gassed with 95% O2-5% CO2 in a special nuclear magnetic resonance (NMR) probe. Renal tubular cellular pH was determined simultaneously from the distribution of 14C-dimethadione (DMO) (pHDMO) or the chemical shift of inorganic phosphate (pHNMR). Experiments were performed at different external pH values (pHe) ranging between 6.52 and 7.20. pHNMR, a measure of cytoplasmic pH, changed by an amount equal to the change in pHe. pHDMO, however, a measure of cytoplasmic plus mitochondrial pH, changed less than pHe as the latter increased. pHDMO, higher than pHNMR at low pHe, became equal to pHNMR at higher pHe values. By use of assumed mitochondrial volumes of 30-40% mitochondrial pH was calculated from pHDMO and pHNMR. Mitochondrial pH remained relatively constant over the entire pHe range studied. Since cytoplasmic pH fell as pHe was lowered, the transmitochondrial pH gradient increased at low pHE values. These findings suggest that the transmitochondrial pH gradient may be important in regulating metabolism.

scholarly journals Complementary and Overlapping Selectivity of the Two-Peptide Bacteriocins Plantaricin EF and JK

1999 ◽  
Vol 181 (16) ◽  
pp. 4848-4852 ◽  
Author(s):  
Gert N. Moll ◽  
Emile van den Akker ◽  
Håvard H. Hauge ◽  
Jon Nissen-Meyer ◽  
Ingolf F. Nes ◽  
...  
Keyword(s):  
Lactobacillus Plantarum ◽  
Ion Selectivity ◽  
Electrical Potential ◽  
High Conductivity ◽  
Ph Gradient ◽  
Target Cells ◽  
Monovalent Cations ◽  
Transmembrane Electrical Potential

ABSTRACT Plantaricin EF and JK are both two-peptide bacteriocins produced byLactobacillus plantarum C11. The mechanism of plantaricin EF and JK action was studied on L. plantarum 965 cells. Both plantaricins form pores in the membranes of target cells and dissipate the transmembrane electrical potential (Δψ) and pH gradient (ΔpH). The plantaricin EF pores efficiently conduct small monovalent cations, but conductivity for anions is low or absent. Plantaricin JK pores show high conductivity for specific anions but low conductivity for cations. These data indicate that L. plantarum C11 produces bacteriocins with complementary ion selectivity, thereby ensuring efficient killing of target bacteria.

Inhibitory effects of Italian ryegrass (Lolium multiflorum Lam.) seedlings of rice (Oryza sativa L.)

2018 ◽  
Vol 44 (2) ◽  
pp. 219-232 ◽  
Author(s):  
S.J Jang ◽  
K.R. Kim ◽  
Y.B. Yun ◽  
S.S. Kim ◽  
Y.I Kuk
Keyword(s):  
Oryza Sativa ◽  
Oryza Sativa L ◽  
Lolium Multiflorum ◽  
Italian Ryegrass ◽  
Inhibitory Effects

Quantitative trait loci analysis of nitrate-nitrogen content in Italian ryegrass (Lolium multiflorum Lam.)

Euphytica ◽  
2021 ◽  
Vol 217 (1) ◽  
Author(s):  
Wenqing Tan ◽  
Di Zhang ◽  
Nana Yuyama ◽  
Jun Chen ◽  
Shinichi Sugita ◽  
...  
Keyword(s):  
Quantitative Trait Loci ◽  
Nitrogen Content ◽  
Quantitative Trait ◽  
Nitrate Nitrogen ◽  
Lolium Multiflorum ◽  
Italian Ryegrass ◽  
Trait Loci

Protection of Italian ryegrass (Lolium multiflorum L.) seedlings from salinity stress following seed priming with L-methionine and casein hydrolysate

2020 ◽  
pp. 1-9
Author(s):  
Keum-Ah Lee ◽  
Youngnam Kim ◽  
Hossein Alizadeh ◽  
David W.M. Leung
Keyword(s):  
Oxidative Stress ◽  
Amino Acids ◽  
Salinity Stress ◽  
Lolium Multiflorum ◽  
Casein Hydrolysate ◽  
Seed Priming ◽  
Germination Percentage ◽  
Italian Ryegrass ◽  
Significant Difference ◽  
Protein Amino Acids

Abstract Seed priming with water (hydropriming or HP) has been shown to be beneficial for seed germination and plant growth. However, there is little information on the effects of seed priming with amino acids and casein hydrolysate (CH) compared with HP, particularly in relation to early post-germinative seedling growth under salinity stress. In this study, Italian ryegrass seeds (Lolium multiflorum L.) were primed with 1 mM of each of the 20 protein amino acids and CH (200 mg l−1) before they were germinated in 0, 60 and 90 mM NaCl in Petri dishes for 4 d in darkness. Germination percentage (GP), radicle length (RL) and peroxidase (POD) activity in the root of 4-d-old Italian ryegrass seedlings were investigated. Generally, when the seeds were germinated in 0, 60 and 90 mM NaCl, there was no significant difference in GP of seeds among various priming treatments, except that a higher GP was observed in seeds of HP treatment compared with the non-primed seeds when incubated in 60 mM NaCl. When incubated in 60 and 90 mM NaCl, seedlings from seeds primed with L-methionine or CH exhibited greater RL (greater protection against salinity stress) and higher root POD activity than those from non-primed and hydro-primed seeds. Under salinity stress, there were higher levels of malondialdehyde (MDA) in the root of 4-d-old Italian ryegrass seedlings, a marker of oxidative stress, but seed priming with CH was effective in reducing the salinity-triggered increase in MDA content. These results suggest that priming with L-methionine or CH would be better than HP for the protection of seedling root growth under salinity stress and might be associated with enhanced antioxidative defence against salinity-induced oxidative stress.

The mitochondrial consequences of uncoupling intact cells depend on the nature of the exogenous substrate

2001 ◽  
Vol 355 (1) ◽  
pp. 231-235 ◽  
Author(s):  
Brigitte SIBILLE ◽  
Céline FILIPPI ◽  
Marie-Astrid PIQUET ◽  
Pascale LECLERCQ ◽  
Eric FONTAINE ◽  
...  
Keyword(s):  
Oxidation Rate ◽  
Marked Decrease ◽  
Electrical Potential ◽  
Atp Synthesis ◽  
Intact Cells ◽  
Isolated Mitochondria ◽  
Exogenous Substrate ◽  
High Oxidation ◽  
Transmembrane Electrical Potential ◽  
Sustained Increase

In isolated mitochondria the consequences of oxidative phosphorylation uncoupling are well defined, whereas in intact cells various effects have been described. Uncoupling liver cells with 2,4-dinitrophenol (DNP) in the presence of dihydroxyacetone (DHA) and ethanol results in a marked decrease in mitochondrial transmembrane electrical potential (∆ψ), ATP/ADP ratios and gluconeogenesis (as an ATP-utilizing process), whereas the increased oxidation rate is limited and transient. Conversely, when DHA is associated with octanoate or proline, DNP addition results in a very large and sustained increase in oxidation rate, whereas the decreases in ∆ψ, ATP/ADP ratios and gluconeogenesis are significantly less when compared with DHA and ethanol. Hence significant energy wastage (high oxidation rate) by uncoupling is achieved only with substrates that are directly oxidized in the mitochondrial matrix. Conversely in the presence of substrates that are first oxidized in the cytosol, uncoupling results in a profound decrease in mitochondrial ∆ψ and ATP synthesis, whereas energy wastage is very limited.

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