Apical control of band elongation in Antithamnion defectum (Ceramiaceae, Rhodophyta)

1988 ◽  
Vol 66 (7) ◽  
pp. 1308-1315 ◽  
Author(s):  
David Garbary ◽  
Daniel Belliveau ◽  
Robert Irwin
Keyword(s):  
Cell Elongation ◽  
Experimental Conditions ◽  
Axial Cell ◽  
Wall Deposition ◽  
Apical Control ◽  
Band Position ◽  
Apical Cells ◽  
In Cells

Cell elongation in the Ceramiaceae typically occurs by means of one or two bands located apically and (or) basally in each cell. In axial cells of Antithamnion defectum two bands are present; however, most cell elongation occurs as a result of new wall deposition in bands at the base of each axial cell. In cells of determinate branches, only the basal band is present. In experimental conditions in which apical cells of indeterminate branches are differentially excised, location of the primary elongation band can be reestablished in relation to remaining indeterminate axes. Thus, the primary elongation band in axial cells is always basal with respect to indeterminate apical cells. When all indeterminate apices are removed, band growth becomes highly disrupted, and diffuse, irregularly located bands are formed. These results suggest that regulation of band position and elongation is through apical control.

scholarly journals A Novel H+ Conductance in Eosinophils

1999 ◽  
Vol 190 (2) ◽  
pp. 183-194 ◽  
Author(s):  
Botond Bánfi ◽  
Jacques Schrenzel ◽  
Oliver Nüsse ◽  
Daniel P. Lew ◽  
Erzsébet Ligeti ◽  
...  
Keyword(s):  
Nadph Oxidase ◽  
The Novel ◽  
Experimental Conditions ◽  
Intact Cells ◽  
Electrophysiological Studies ◽  
Dependent Signal ◽  
Low Threshold ◽  
Nadph Oxidase Activation ◽  
In Cells

Efficient mechanisms of H+ ion extrusion are crucial for normal NADPH oxidase function. However, whether the NADPH oxidase—in analogy with mitochondrial cytochromes—has an inherent H+ channel activity remains uncertain: electrophysiological studies did not find altered H+ currents in cells from patients with chronic granulomatous disease (CGD), challenging earlier reports in intact cells. In this study, we describe the presence of two different types of H+ currents in human eosinophils. The “classical” H+ current had properties similar to previously described H+ conductances and was present in CGD cells. In contrast, the “novel” type of H+ current had not been described previously and displayed unique properties: (a) it was absent in cells from gp91- or p47-deficient CGD patients; (b) it was only observed under experimental conditions that allowed NADPH oxidase activation; (c) because of its low threshold of voltage activation, it allowed proton influx and cytosolic acidification; (d) it activated faster and deactivated with slower and distinct kinetics than the classical H+ currents; and (e) it was ∼20-fold more sensitive to Zn2+ and was blocked by the histidine-reactive agent, diethylpyrocarbonate (DEPC). In summary, our results demonstrate that the NADPH oxidase or a closely associated protein provides a novel type of H+ conductance during phagocyte activation. The unique properties of this conductance suggest that its physiological function is not restricted to H+ extrusion and repolarization, but might include depolarization, pH-dependent signal termination, and determination of the phagosomal pH set point.

scholarly journals Interaction between Wall Deposition and Cell Elongation in Dark-Grown Hypocotyl Cells in Arabidopsis

2004 ◽  
Vol 135 (2) ◽  
pp. 959-968 ◽  
Author(s):  
Guislaine Refrégier ◽  
Sandra Pelletier ◽  
Danielle Jaillard ◽  
Herman Höfte
Keyword(s):  
Cell Elongation ◽  
Wall Deposition

Observations upon the Recovery of Oxyntic Cells after Prolonged Dosage with Pilocarpine or Histamine

1952 ◽  
Vol s3-93 (24) ◽  
pp. 385-390
Author(s):  
GORDON MENZIES
Keyword(s):  
Acid Phosphatase ◽  
Neck Region ◽  
Basal Cells ◽  
Experimental Conditions ◽  
Multiple Doses ◽  
In Cells

1. New observations are presented concerning the structure and cytochemistry of the granules in the oxyntic cells of the rat,s stomach, in continuation of work already reported (Menzies, 1949, 1952 a and 6). 2. The phospholipine component of the granules is slowly regained after being depleted by multiple doses of pilocarpine or histamine. 3. The phospholipine is first regained by the granules in those oxyntic cells situated at the basal ends of the gastric tubules, and later by the remaining cells in the neck of the tubules. 4. An acid phosphatase appears in the oxyntic cells whose granules are about to regain their lipine component, and disappears some time after they have done so. 5. The order in which both the acid phosphatase and the lipine appears (first in the basal cells and later in cells in the neck region) is the same as that in which an acid phosphatase appears when and as the lipine is being shed under experimental conditions (Menzies, 1952 b).

Elevated extracellular Mg2+ increases Mg2+ buffering through a Ca-dependent mechanism in cardiomyocytes

1994 ◽  
Vol 267 (2) ◽  
pp. C633-C641 ◽  
Author(s):  
K. L. Koss ◽  
R. D. Grubbs
Keyword(s):  
Ventricular Myocytes ◽  
Pharmacological Action ◽  
Metabolic Inhibitors ◽  
Therapeutic Concentration ◽  
Experimental Conditions ◽  
Physiological Basis ◽  
Fura 2 ◽  
Dependent Mechanism ◽  
In Cells

To investigate the physiological basis for the pharmacological action of extracellular magnesium (Mg2+O), cultured ventricular myocytes were exposed to either 0.8 mM (physiological) or 5.0 mM Mg2+ (therapeutic concentration) in the presence and absence of metabolic inhibitors. Metabolic inhibition, induced with 1 mM iodoacetate and 1 mM NaCN, was used to liberate Mg2+ from MgATP into the myoplasm, permitting examination of the role of elevated Mg2+O on myoplasmic Mg2+ buffering. The increase in Mg2+ activity observed in the presence of 5 mM Mg2+O was diminished compared with that observed in cells exposed to 0.8 mM Mg2+O. Furthermore, the increase in myoplasmic Mg2+ activity observed in the presence of 5 mM Mg2+O was identical to that reported previously in the absence of extracellular Ca2+. Fura 2 measurements of Ca2+ activity in these experimental conditions suggested that the Ca2+ permeability of cells conditions suggested that the Ca2+ permeability of cells exposed to 5 mM Mg2+ was less than that observed for cells exposed to 0.8 mM Mg2+. Using the Mg2+ buffer coefficient to quantitate cellular Mg2+ buffering, we observed a 63% increase in Mg2+ buffering in cells exposed to 5 mM Mg2+ compared with cells exposed to 0.8 mM Mg2+. This study demonstrates that elevated Mg2+O alters cardiomyocyte myoplasmic Mg2+ activity as the result of increased Mg2+ buffering through a Ca(2+)-sensitive mechanism.

scholarly journals Biochemical and Biophysical Characterization of the Enolase from Helicobacter pylori

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
María de J. López-López ◽  
Isabel C. Rodríguez-Luna ◽  
Edgar E. Lara-Ramírez ◽  
Marisol López-Hidalgo ◽  
Claudia G. Benítez-Cardoza ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Activation Enthalpy ◽  
New Drugs ◽  
Gastric Diseases ◽  
Experimental Conditions ◽  
Extracellular Rna ◽  
Wide Range ◽  
Glycolysis Pathway ◽  
H Pylori ◽  
In Cells

Enolase, which catalyses the conversion of 2-phospho-D-glycerate to phosphoenolpyruvate, is an important enzyme in the classic glycolysis pathway in cells. Enolase is highly conserved in organisms from bacteria to humans, indicating its importance in cells. Thus, enolase is a good target for developing new drugs. In the last decade, new functions of this enzyme have been found. Helicobacter pylori is a common human pathogen that causes gastric diseases and even gastric cancer. In this study, the sequence of H. pylori enolase (HpEno) was analysed; the conservation (at least partial) of binding sites for cofactor, plasminogen, and host extracellular RNA, as well as catalytic site, indicates that HpEno should be capable of performing the functions. Recombinant HpEno was overexpressed and purified from E. coli. Compared to the enolases from other species, HpEno had similar characteristics for its secondary structure. The temperature-induced profiles indicate that HpEno is quite stable to temperature, compared to other homologs. Regarding the kinetics of the unfolding reaction, we found that the activation enthalpy associated with the thermal unfolding reaction is equivalent to the reported activation enthalpy for yeast enolase, indicating a similar scaffold and kinetic stability. Although a wide range of experimental conditions were assayed, it was not possible to detect any enzymatic activity of HpEno. To prove the lack of activity, still a much wider range of experiments should be carried out.

scholarly journals Effect of the α-agonist noradrenaline on total and 45Ca2+ movements in mitochondria of rat liver cells

1981 ◽  
Vol 200 (1) ◽  
pp. 177-180 ◽  
Author(s):  
Brigitte Berthon ◽  
Josiane Poggioli ◽  
Thierry Capiod ◽  
Michel Claret
Keyword(s):  
Rat Liver ◽  
Liver Cells ◽  
Isolated Cells ◽  
Experimental Conditions ◽  
Rat Liver Cells ◽  
Rat Livers ◽  
In Cells

Ca2+ movements triggered by noradrenaline were determined in isolated cells and mitochondria from rat livers. It has been shown that these depend on experimental conditions. In cells incubated in 1.8mm-Ca2+, results suggest that noradrenaline mobilizes Ca2+ from reticulum before releasing Ca2+ from mitochondria.

scholarly journals High-throughput living-cell protein crosslinking analysis uncovers the physiological relevance of forming the “inserted” state of the ATP synthase ε-subunit

2019 ◽  
Author(s):  
Yang Liu ◽  
Jiayu Yu ◽  
Mengyuan Wang ◽  
Qingfang Zeng ◽  
Xinmiao Fu ◽  
...  
Keyword(s):  
Atp Synthase ◽  
High Throughput ◽  
Living Cell ◽  
Polyacrylamide Gel Electrophoresis ◽  
Unnatural Amino Acid ◽  
Fine Tuning ◽  
Cell Protein ◽  
Experimental Conditions ◽  
Physiological Relevance ◽  
In Cells

AbstractATP synthase, a highly conserved multi-subunit enzyme complex having a common stoichiometry of α3β3γδεab2c8-15, functions to supply ATP as the universal energy currency for cells. It comprises of the peripheral F1 sector (α3β3γδε) and the membrane-integrated Fo sector (ab2c8-15). In vitro structural analyses revealed that the C-terminal domain of the ε-subunit could adopt either an “inserted” or “non-inserted” state (with or without interacting with the α/β-subunits), with the former being viewed as inhibitory for the ATP hydrolysis activity of ATP synthase. Nevertheless, as common in current protein researches, the physiological relevance of such an “inserted” state for ATP synthase functioning is hardly known. To decipher this, designed an unnatural amino acid-mediated living-cell protein photocrosslinking analysis pipeline by developing the scarless genome-targeted site-directed mutagenesis and the high-throughput gel polyacrylamide gel electrophoresis (HT-PAGE) techniques. Employing this powerful approach, we systematically examined the interactions involving the C-terminal helix of the ε-subunit in cells living under a variety of experimental conditions. These studies enabled us to uncover that the “inserted” and “non-inserted” states of the ε-subunit exist as an equilibrium in cells cultured under common experimental conditions, shifting to the former upon the appearance of unfavorable conditions, acting as a low-gear state to strengthen the ATP synthesis function. Such a fine-tuning mechanism allows the ATP synthase to reversibly and instantly switch between two functional states. Further, the two powerful techniques that we developed here might be applied to many aspects of protein researches.

scholarly journals Molecular Profiling and Optimization Studies for Growth and PHB Production Conditions in Rhodobacter sphaeroides

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6471
Author(s):  
Yu Rim Lee ◽  
Hana Nur Fitriana ◽  
Soo Youn Lee ◽  
Min-Sik Kim ◽  
Myounghoon Moon ◽  
...  
Keyword(s):  
Time Course ◽  
Growth Conditions ◽  
Effect Of Temperature ◽  
Ros Scavenging ◽  
Renewable Materials ◽  
Experimental Conditions ◽  
Expression Levels ◽  
Recent Climate ◽  
Phb Production ◽  
In Cells

In the recent climate change regime, industrial demand for renewable materials to replace petroleum-derived polymers continues to rise. Of particular interest is polyhydroxybutyrate (PHB) as a substitute for polypropylene. Accumulating evidence indicates that PHB is highly produced as a carbon storage material in various microorganisms. The effects of growth conditions on PHB production have been widely studied in chemolithotrophs, particularly in Rhodobacter. However, the results on PHB production in Rhodobacter have been somewhat inconsistent due to different strains and experimental conditions, and it is currently unclear how diverse environmental factors are linked with PHB production. Here, we report optimized growth conditions for PHB production and show that the growth conditions are closely related to reactive oxygen species (ROS) regulation. PHB accumulates in cells up to approximately 50% at the highest level under dark-aerobic conditions as opposed to light aerobic/anaerobic conditions. According to the time-course, PHB contents increased at 48 h and then gradually decreased. When observing the effect of temperature and medium composition on PHB production, 30 °C and a carbon/nitrogen ratio of 9:1 or more were found to be most effective. Among PHB biosynthetic genes, PhaA and PhaB are highly correlated with PHB production, whereas PhaC and PhaZ showed little change in overall expression levels. We found that, while the amount of hydrogen peroxide in cells under dark conditions was relatively low compared to the light conditions, peroxidase activities and expression levels of antioxidant-related genes were high. These observations suggest optimal culture conditions for growth and PHB production and the importance of ROS-scavenging signaling with regard to PHB production.

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