scholarly journals Control of intracellular pH. Predominant role of oxidative metabolism, not proton transport, in the eukaryotic microorganism Neurospora.

1982 ◽  
Vol 80 (3) ◽  
pp. 377-402 ◽  
Author(s):  
D Sanders ◽  
C L Slayman
Keyword(s):  
Proton Pump ◽  
Weak Acid ◽  
Weak Base ◽  
Passive Permeability ◽  
Stress Changes ◽  
Internal Ph ◽  
Principal Source ◽  
Cytoplasmic Acidification ◽  
Intracellular Buffering Capacity

Recessed-tip microelectrodes were used to measure internal pH (pHi) in the fungus Neurospora, and to examine the response of pHi to several kinds of stress: changes of extracellular pH (pHo), inhibition of the principal proton pump in the plasma membrane, and inhibition of respiration. Under control conditions, at pHo = 5.8, pHi in Neurospora is 7.19 +/- 0.04. Changes of pHo between 3.9 and 9.3 affect pHi linearly but with a slope of only approximately 0.1 unit pHi per unit pHo, stable pHi being reached within 3 min of changed pHo. Despite a postulated high passive permeability of the Neurospora membrane to protons (Slayman, 1970), neither active nor passive H+ transport appears critical to pHi because (alpha) specific inhibition of the proton pump by orthovanadate has little effect on pHi, and (b) cytoplasmic acidification produced by respiratory blockade is unaffected by the size or direction of proton gradient. To convert measured changes in pHi into net proton fluxes, intracellular buffering capacity (beta i) was measured by the weak acid/weak base technique. At pHi = 7.2, beta i was (-) 35 mmol H+ (liter cell water)-1 (pH unit)-1, but beta i increased substantially in both the acid and alkaline directions, which suggests that amino acid side chains are the principal source of buffer.

scholarly journals Rapid patterning and zonal differentiation in a two-dimensionalDictyosteliumcell mass: the role of pH and ammonia

2002 ◽  
Vol 205 (17) ◽  
pp. 2583-2590
Author(s):  
Satoshi Sawai ◽  
Takashi Hirano ◽  
Yasuo Maeda ◽  
Yasuji Sawada
Keyword(s):  
Cell Differentiation ◽  
Outer Zone ◽  
Cell Types ◽  
Reaction Scheme ◽  
Weak Acid ◽  
Weak Base ◽  
Cytosolic Ph ◽  
Different Cell Types ◽  
Plasma Membrane Proton Pump

SUMMARYRecently it was demonstrated that a rapidly forming, self-organizing pattern that emerges within two-dimensional Dictyostelium discoideumcell cultures could later give rise to stripes of distinct zones, each comprising different cell types. Here we report physiological aspects of the initial rapid patterning and its relationship to cell differentiation. We found that as the temperature is lowered the characteristic length of the pattern increases. From this we estimated the activation energy of the patterning kinetics. Fluorescence of fluorescein-conjugated dextran revealed that the cytosolic pH of cells in the inside zone becomes lower than that in the outer zone facing the air. The patterning could be inhibited by addition of the plasma-membrane proton pump inhibitors diethystilbestrol (DES) or miconazole. Preincubation of cells with weak acid delayed the timing of the patterning, whereas weak base hastened it. A pH-indicating dye revealed localized accumulation of ammonia in the extracellular space. These results suggest that gradients of secreted metabolites may be directly responsible for the rapid patterning and its consequence on cell differentiation in a confined geometrical situation. Possible diffusible candidate molecules and a reaction scheme coupled to the imposed oxygen gradient are discussed.

scholarly journals Effects of cytoplasmic acidification on clathrin lattice morphology.

1989 ◽  
Vol 108 (2) ◽  
pp. 401-411 ◽  
Author(s):  
J Heuser
Keyword(s):  
Plasma Membrane ◽  
Cultured Cells ◽  
Membrane Receptors ◽  
The Other ◽  
Culture Dish ◽  
Initial Curvature ◽  
Internal Ph ◽  
Cytoplasmic Acidification

Reducing the internal pH of cultured cells by several different protocols that block endocytosis is found to alter the structure of clathrin lattices on the inside of the plasma membrane. Lattices curve inward until they become almost spherical yet remain stubbornly attached to the membrane. Also, the lattices bloom empty "microcages" of clathrin around their edges. Correspondingly, broken-open cells bathed in acidified media demonstrate similar changes in clathrin lattices. Acidification accentuates the normal tendency of lattices to round up in vitro and also stimulates them to nucleate microcage formation from pure solutions of clathrin. On the other hand, several conditions that also inhibit endocytosis have been found to create, instead of unusually curved clathrin lattices with extraneous microcages, a preponderance of unusually flat lattices. These treatments include pH-"clamping" cells at neutrality with nigericin, swelling cells with hypotonic media, and sticking cells to the surface of a culture dish with soluble polylysine. Again, the unusually flat lattices in such cells display a tendency to round up and to nucleate clathrin microcage formation during subsequent in vitro acidification. This indicates that regardless of the initial curvature of clathrin lattices, they all display an ability to grow and increase their curvature in vitro, and this is enhanced by lowering ambient pH. Possibly, clathrin lattice growth and curvature in vivo may also be stimulated by a local drop in pH around clusters of membrane receptors.

Links between pond and dike, their potential and impacts on livelihood.

2020 ◽  
Author(s):  
Manjurul Karim ◽  
Md. Abdul Wahab ◽  
David Little ◽  
Md. Shamsul ◽  
V. Marc
Keyword(s):  
Urban Areas ◽  
Water Reservoir ◽  
Fish Farming ◽  
Important Food ◽  
Urban Households ◽  
Productive System ◽  
Principal Source ◽  
The Cost ◽  
Inland Water Bodies

Abstract Aquaculture and horticulture are interlinked and both of these agricultural components have considerable importance in the economy of Bangladesh. Most people in this country depend on fish as the principal source of animal protein. Vegetables are also considered by Bangladeshi people as important food items and as a source of micronutrients. Ponds, among various inland water bodies, are the most important water reservoir, providing access to fish, irrigation for surrounding vegetables and rice crops and water for family use, and thus are an integral part of rural and peri-urban households. Integration of crops with fish farming through pond-dike systems may be an economically viable and productive system for both richer and poorer farmers in rural and peri-urban areas in Bangladesh. High-cost inputs in fish farming are not needed in such pond-dike systems, therefore reducing the cost of inputs, provided that there is proper integration between pond and crops grown in the vicinity. A community-level assessment of the importance and role of pond-dike systems and a baseline study, carried out in villages in Mymensingh district in early 2002 by the Pondlive project funded by the European Commission, are outlined.

Cytoplasmic acidification is not an effector mechanism of VP16 or DEX-induced apoptosis in CEM T leukaemia cells

1999 ◽  
Vol 112 (11) ◽  
pp. 1755-1760
Author(s):  
R.S. Benson ◽  
C. Dive ◽  
A.J. Watson
Keyword(s):  
Chromatin Condensation ◽  
Parp Cleavage ◽  
Intracellular Acidification ◽  
Over Expression ◽  
Effector Phase ◽  
Execution Phase ◽  
Cytoplasmic Acidification ◽  
Physiological Values ◽  
Induced Apoptosis

The role of intracellular acidification in the execution phase of apoptosis is not well understood. Here we examine the effect of Bcl-2 over-expression on intracellular acidification occurring during apoptosis. We found, that in CEM cells, neither DEX nor VP16-induced apoptosis lead to a significant change in intracellular pH (pHi). Furthermore, we found that shifting pHi away from physiological values was unable to induce chromatin condensation or poly(ADP-ribose) polymerase (PARP) cleavage in the presence of Bcl-2 over-expression. However, it was found that maximum chromatin condensation and PARP cleavage occurred at near physiological pHi values. Taken together these data suggest that intracellular acidification does not trigger the effector phase of CEM apoptosis.

scholarly journals Duodenal Dysbiosis and Relation to the Efficacy of Proton Pump Inhibitors in Functional Dyspepsia

2021 ◽  
Vol 22 (24) ◽  
pp. 13609
Author(s):  
Lucas Wauters ◽  
Raúl Y. Tito ◽  
Matthias Ceulemans ◽  
Maarten Lambaerts ◽  
Alison Accarie ◽  
...  
Keyword(s):  
Functional Dyspepsia ◽  
Proton Pump Inhibitors ◽  
Proton Pump ◽  
Potential Role ◽  
Short Term ◽  
Beneficial Effects ◽  
Rrna Sequencing ◽  
Before And After

Proton pump inhibitors (PPI) may improve symptoms in functional dyspepsia (FD) through duodenal eosinophil-reducing effects. However, the contribution of the microbiome to FD symptoms and its interaction with PPI remains elusive. Aseptic duodenal brushings and biopsies were performed before and after PPI intake (4 weeks Pantoprazole 40 mg daily, FD-starters and controls) or withdrawal (2 months, FD-stoppers) for 16S-rRNA sequencing. Between- and within-group changes in genera or diversity and associations with symptoms or duodenal factors were analyzed. In total, 30 controls, 28 FD-starters and 19 FD-stoppers were followed. Mucus-associated Porphyromonas was lower in FD-starters vs. controls and correlated with symptoms in FD and duodenal eosinophils in both groups, while Streptococcus correlated with eosinophils in controls. Although clinical and eosinophil-reducing effects of PPI therapy were unrelated to microbiota changes in FD-starters, increased Streptococcus was associated with duodenal PPI effects in controls and remained higher despite withdrawal of long-term PPI therapy in FD-stoppers. Thus, duodenal microbiome analysis demonstrated differential mucus-associated genera, with a potential role of Porphyromonas in FD pathophysiology. While beneficial effects of short-term PPI therapy were not associated with microbial changes in FD-starters, increased Streptococcus and its association with PPIeffects in controls suggest a role for duodenal dysbiosis after long-term PPI therapy.

scholarly journals Role of altered esophageal intraluminal baseline impedance levels in patients with gatroesophageal reflux disease refractory to proton pump inhibitors

Medicine ◽  
2016 ◽  
Vol 95 (33) ◽  
pp. e4351 ◽  
Author(s):  
Liuqin Jiang ◽  
Bixing Ye ◽  
Lin Lin ◽  
Ying Wang ◽  
Meifeng Wang
Keyword(s):  
Proton Pump Inhibitors ◽  
Proton Pump ◽  
Reflux Disease
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