Measurements of Ca 2+ fluxes in intact plant cells

1992 ◽  
Vol 338 (1283) ◽  
pp. 73-82 ◽  
Keyword(s):  
Signal Transduction ◽  
Direct Method ◽  
Plant Cells ◽  
Giant Cells ◽  
Chara Corallina ◽  
Resting Cells ◽  
Cytosolic Ph ◽  
Wide Range ◽  
Cell Turgor ◽  
In Cells

Owing to the central role of Ca 2+ in signal transduction processes, it is important to measure membrane fluxes of Ca 2+ in cells which are as undisturbed as possible, particularly when studying the control of these fluxes. To this end, techniques have been developed to measure Ca 2+ fluxes in intact, turgid plant cells. The measurements are principally of influx across the plasma membrane where Ca 2+ transport is likely to occur through cation-selective channels. The most direct method measures tracer fluxes of Ca 2+ , but special procedures are required to distinguish between influx and extracellular binding of Ca 2+ . Unfortunately, such techniques are currently only applicable to giant cells where surgical separation of the intracellular contents from the cell wall is possible. The influx of Ca 2+ into normal, resting cells of the green alga Chara corallina is usually about 0.3 nmol m -2 s -1 (at an external Ca 2+ concentration of 0.5 mol m -3 ). This flux is up to 5 times higher in actively growing cells, 20 times higher in cells depolarized by 20 mol m -3 K + and 1000 times higher during an action potential. Reducing cell turgor by a wide range of solutes increases Ca 2+ influx, especially near plasmolysis. Ca 2+ influx is sensitive to alterations in both external and cytosolic pH, but is inhibited by complete darkness and by low concentrations of La 3+ . Various organic Ca 2+ channel antagonists had mixed effects on Ca 2+ influx into Chara . The work described in this paper should enable further study of the control of Ca 2+ fluxes into intact, turgid plant cells, and their role in signal transduction and the control of cellular activities.

Review: Molecular response of plant cells to UV-B stress

2002 ◽  
Vol 29 (8) ◽  
pp. 909 ◽  
Author(s):  
Brian R. Jordan
Keyword(s):  
Gene Expression ◽  
Signal Transduction ◽  
Plant Cells ◽  
Environmental Parameters ◽  
Induced Response ◽  
Molecular Response ◽  
Wide Range ◽  
Transduction Mechanisms ◽  
Gene Expression Studies ◽  
Induced Signal

UV-B radiation (UV-B: 280-320 nm) can cause a wide range of responses in plant cells. These responses depend on the perception of the UV-B radiation, signal transduction mechanisms, and modification of gene expression. Studies over the last ten years have revealed a complex molecular response of plant cells to UV-B radiation. A number of signal transduction pathways are established and specific changes in gene activity take place. In addition, other environmental parameters strongly influence the UV-B-induced response. Although molecular studies have advanced our knowledge, our understanding of UV-B-induced cellular changes remains limited compared with other areas of plant photobiology / molecular biology. This review will focus on UV-B-induced signal transduction, gene expression and defence mechanisms. Comparisons will be made with other light-regulated systems to provide an insight into UV-B responses. This review will also attempt to identify present limitations to our understanding of molecular responses of plant cells to UV-B radiation.

Solvent-Ligand Interactions in Colloidal Nanocrystals

2018 ◽  
Author(s):  
Jonathan De Roo ◽  
Nuri Yazdani ◽  
Emile Drijvers ◽  
Alessandro Lauria ◽  
Jorick Maes ◽  
...  
Keyword(s):  
Direct Method ◽  
Line Broadening ◽  
H Nmr ◽  
Size Dependent ◽  
Line Shape Analysis ◽  
Wide Range ◽  
Nanocrystal Synthesis ◽  
Ligand Interactions ◽  
Indispensable Tool ◽  
Theoretical Evidence

<p>Although solvent-ligand interactions play a major role in nanocrystal synthesis, dispersion formulation and assembly, there is currently no direct method to study this. Here we examine the broadening of <sup>1</sup>H NMR resonances associated with bound ligands, and turn this poorly understood descriptor into a tool to assess solvent-ligand interactions. We show that the line broadening has both a homogeneous and a heterogeneous component. The former is nanocrystal-size dependent and the latter results from solvent-ligand interactions. Our model is supported by experimental and theoretical evidence that correlates broad NMR lines with poor ligand solvation. This correlation is found across a wide range of solvents, extending from water to hexane, for both hydrophobic and hydrophilic ligand types, and for a multitude of oxide, sulfide and selenide nanocrystals. Our findings thus put forward NMR line shape analysis as an indispensable tool to form, investigate and manipulate nanocolloids.</p>

scholarly journals Responses to Ecopollutants and Pathogenization Risks of Saprotrophic Rhodococcus Species

Pathogens ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 974
Author(s):  
Irina B. Ivshina ◽  
Maria S. Kuyukina ◽  
Anastasiia V. Krivoruchko ◽  
Elena A. Tyumina
Keyword(s):  
Survival Strategies ◽  
Complex Life Cycle ◽  
Anthropogenic Pressure ◽  
Resting Cells ◽  
Organic Substrates ◽  
Negative Effects ◽  
Anthropogenic Pollutants ◽  
Rhodococcus Species ◽  
Wide Range ◽  
Rigid Cell Wall

Under conditions of increasing environmental pollution, true saprophytes are capable of changing their survival strategies and demonstrating certain pathogenicity factors. Actinobacteria of the genus Rhodococcus, typical soil and aquatic biotope inhabitants, are characterized by high ecological plasticity and a wide range of oxidized organic substrates, including hydrocarbons and their derivatives. Their cell adaptations, such as the ability of adhering and colonizing surfaces, a complex life cycle, formation of resting cells and capsule-like structures, diauxotrophy, and a rigid cell wall, developed against the negative effects of anthropogenic pollutants are discussed and the risks of possible pathogenization of free-living saprotrophic Rhodococcus species are proposed. Due to universal adaptation features, Rhodococcus species are among the candidates, if further anthropogenic pressure increases, to move into the group of potentially pathogenic organisms with “unprofessional” parasitism, and to join an expanding list of infectious agents as facultative or occasional parasites.

Two-Color Probe to Monitor a Wide Range of pH Values in Cells

2013 ◽  
Vol 52 (24) ◽  
pp. 6206-6209 ◽  
Author(s):  
Min Hee Lee ◽  
Ji Hye Han ◽  
Jae Hong Lee ◽  
Nayoung Park ◽  
Rajesh Kumar ◽  
...  
Keyword(s):  
Ph Values ◽  
Wide Range ◽  
In Cells

A novel electrochemical conducting polymer sensor for the rapid, selective and sensitive detection of biothiols

2021 ◽  
Author(s):  
Bicheng Zhu ◽  
Devon Bryant ◽  
Alireza Akbarinejad ◽  
Jadranka Travas-Sejdic ◽  
Lisa I Pilkington
Keyword(s):  
Conducting Polymer ◽  
Sensitive Detection ◽  
Bodily Fluids ◽  
Wide Range ◽  
In Cells

Biological thiols (biothiols) in cells and bodily fluids are intrinsically linked to the functioning of important enzymes, deficiency in which can lead to a wide range of physiological and pathological...

Elicitor Recognition and Signal Transduction in Plant Defense Gene Activation

1990 ◽  
Vol 45 (6) ◽  
pp. 569-575 ◽  
Author(s):  
Dierk Scheel ◽  
Jane E. Parker
Keyword(s):  
Signal Transduction ◽  
Plant Defense ◽  
Transcriptional Activation ◽  
Molecular Mechanisms ◽  
Plant Protection ◽  
Plant Cells ◽  
Defense Responses ◽  
Plant Defense Responses ◽  
Defense Genes ◽  
Plant Defense Genes

Abstract Plants defend themselves against pathogen attack by activating a whole set of defense responses, most of them relying on transcriptional activation of plant defense genes. The same responses are induced by treatment of plant cells with elicitors released from the pathogen or from the plant surface. Several plant/elicitor combinations have been used successfully as experimental systems to investigate the molecular basis of plant defense responses. Receptor-like structures on the plasma membrane of plant cells appear to bind the elicitors. Thereby, intracellular signal transduction chains are initiated which finally result in the activation of plant defense genes. A better understanding of the molecular mechanisms of early processes in plant defense responses, as provided by these studies, may in the long term help to develop environmentally safe plant protection methods for agriculture.

Two-Color Probe to Monitor a Wide Range of pH Values in Cells

2013 ◽  
Vol 125 (24) ◽  
pp. 6326-6329 ◽  
Author(s):  
Min Hee Lee ◽  
Ji Hye Han ◽  
Jae Hong Lee ◽  
Nayoung Park ◽  
Rajesh Kumar ◽  
...  
Keyword(s):  
Ph Values ◽  
Wide Range ◽  
In Cells

Histidine kinases in signal transduction pathways of eukaryotes

1997 ◽  
Vol 110 (10) ◽  
pp. 1141-1145 ◽  
Author(s):  
W.F. Loomis ◽  
G. Shaulsky ◽  
N. Wang
Keyword(s):  
Signal Transduction ◽  
Response Regulator ◽  
Signal Transduction Pathways ◽  
Response Regulators ◽  
Histidine Kinases ◽  
Camp Phosphodiesterase ◽  
Wide Range ◽  
Two Component ◽  
Two Component Signal Transduction ◽  
Dependent Protein

Autophosphorylating histidine kinases are an ancient conserved family of enzymes that are found in eubacteria, archaebacteria and eukaryotes. They are activated by a wide range of extracellular signals and transfer phosphate moieties to aspartates found in response regulators. Recent studies have shown that such two-component signal transduction pathways mediate osmoregulation in Saccharomyces cerevisiae, Dictyostelium discoideum and Neurospora crassa. Moreover, they play pivotal roles in responses of Arabidopsis thaliana to ethylene and cytokinin. A transmembrane histidine kinase encoded by dhkA accumulates when Dictyostelium cells aggregate during development. Activation of DhkA results in the inhibition of its response regulator, RegA, which is a cAMP phosphodiesterase that regulates the cAMP dependent protein kinase PKA. When PKA is activated late in the differentiation of prespore cells, they encapsulate into spores. There is evidence that this two-component system participates in a feedback loop linked to PKA in prestalk cells such that the signal to initiate encapsulation is rapidly amplified. Such signal transduction pathways can be expected to be found in a variety of eukaryotic differentiations since they are rapidly reversible and can integrate disparate signals.

Are Polyphosphoinositides Involved in Signal Transduction of Elicitor-Induced Phytoalexin Synthesis in Cultured Plant Cells ?

1986 ◽  
Vol 41 (7-8) ◽  
pp. 717-724 ◽  
Author(s):  
Heiner Strasser ◽  
Christina Hoffmann ◽  
Hans Grisebach ◽  
Ulrich Matern
Keyword(s):  
Signal Transduction ◽  
Significant Influence ◽  
Plant Cells ◽  
Two Dimensional ◽  
Phytoalexin Synthesis

Abstract The phospholipids of cultured parsley and soybean cells were labelled with myo-[2-3H]inositol, [2-3H]glycerol or [32P]orthophosphate. By one-and two-dimensional chromatographic comparison of the labelled phospholipids with reference substances, the presence of 1-(3-sn-phosphatidyl)-ᴅ-myo-inositol 4-phosphate and 1-(3-sn-phosphatidyl)-ᴅ-myo-inositol 4,5-bisphosphate was demonstrated in these cultures. These results were corroborated by analysis of the deacylation products. Cells were labelled with either myo-[2-3H]inositol, [2-3H]glycerol or [32P]orthophosphate and subsequently challenged with elicitor for various lengths of time. Radioactivity in individual phosphoinositides from these cells was determined. No significant influence of elicitor-challenge of either soybean or parsley cells on incorporation of 3H or 32P into polyphospho­inositides was found between 0.5 and 20 min after elicitor addition.

scholarly journals Three routine methods for measuring high-density lipoprotein cholesterol compared with the Reference Method

1996 ◽  
Vol 42 (5) ◽  
pp. 738-743 ◽  
Author(s):  
N Harris ◽  
V Galpchian ◽  
N Rifai
Keyword(s):  
High Density Lipoprotein ◽  
High Density Lipoprotein Cholesterol ◽  
Dextran Sulfate ◽  
Direct Method ◽  
Density Lipoprotein ◽  
Reference Method ◽  
High Density ◽  
Lipoprotein Cholesterol ◽  
Direct Assay ◽  
Wide Range

Abstract We compared the performance of three methods for quantifying high-density lipoprotein cholesterol (HDL-C) with the Reference Method for HDL-C, using samples with a wide range of triglyceride (TG) concentrations (290-18000 mg/L). All three comparison assays-- utilizing a magnetic dextran sulfate precipitating reagent, a direct method, and a standard MgCl2-dextran sulfate reagent--were precise, with a run-to-run CV of less than or equal to 4.1%. However, the systematic error of these assays exceeded the National Cholesterol Education Program (NCEP) performance goal of less than or equal to 10% in half of the concentration ranges tested. Nevertheless, the total error of the assays generally meets the current 22% limit set by the NCEP. Although both the magnetic dextran sulfate precipitation reagent and the direct assay can be performed more rapidly than the MgCl2-dextran sulfate assay, the direct assay involves no sample preparation and requires only 4 microL of sample excluding the dead space. Although precipitation is frequently inadequate with the MgCl2-dextran sulfate reagent at TG concentrations &gt;6000 mg/L, both the magnetic and the direct reagent show no interference from high TG concentrations as great as 18 000 mg/L.

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