Calcium and the generation of plant form

1995 ◽  
Vol 350 (1331) ◽  
pp. 83-86 ◽  
Keyword(s):  
Plant Development ◽  
Calcium Concentration ◽  
Cytosolic Calcium ◽  
Hypocotyl Growth ◽  
Mechanical Signals ◽  
Tension And Compression ◽  
Plant Form ◽  
Living Organisms ◽  
Exciting Possibility

The involvement of mechanical signals (tension and compression) in the determination of the form of living organisms has been speculated upon for many years. These mechanical signals (both environmental and those generated within the plant itself) have significant effects on plant development and thus morphology. Plants respond to externally applied mechanical signals (touch and wind) by an immediate elevation of cytosolic calcium concentration ([Ca 2+ ] eyt ) in stimulated cells. This response requires the movement of plant tissues to cause tension and compression. Some of the more longer-term responses to mechanical signals, e.g. TCH gene expression and reduction in hypocotyl growth, show a calcium-dependency. It seems likely, therefore, that the effects of mechanical signals on plant development are mediated by the second messenger, calcium. This raises the exciting possibility that this simple ion plays a central role in the determination of plant form itself.

Hypersensitivity to Thromboxane A2 in Cholesterol-Rich Human Platelets

1990 ◽  
Vol 64 (04) ◽  
pp. 594-599 ◽  
Author(s):  
Takuya Tomizuka ◽  
Kyohei Yamamoto ◽  
Aizan Hirai ◽  
Yasushi Tamura ◽  
Sho Yoshida
Keyword(s):  
Calcium Concentration ◽  
Binding Capacity ◽  
Thromboxane A2 ◽  
Cytosolic Calcium ◽  
Cholesterol Content ◽  
Human Platelets ◽  
Dissociation Rate ◽  
Platelet Membrane ◽  
Maximal Concentration ◽  
Equilibrium Dissociation

SummaryThe effect of changes in platelet membrane cholesterol content on thromboxane A2 (TXA2)-induced platelet activation was studied. Concentrations of 9,ll-epithio-ll,12-methano-TXA2 (STA2), a stable analogue of TXA2 which can cause half-maximal aggregation and release of [14C]serotonin in cholesterol-rich platelets were significantly lower than those in cholesterol-normal platelets. STA2-induced increase in cytosolic calcium concentration and [32P]phosphatidic acid formation in cholesterol-rich platelets were significantly greater than those in cholesterol-normal platelets. The maximal concentration of binding site (Bmax) for SQ29548 was significantly increased in cholesterol-rich platelets compared with cholesterol-normal platelets, while the equilibrium dissociation rate constant (Kd) for SQ29548 did not differ between cholesterol-rich and cholesterol-normal platelets. The present study suggested that sensitivity to TXA2 was increased by the incorporation of cholesterol into platelet membrane and that the cause of hypersensitivity to TXA2 in cholesterol-rich platelets may be partly explained by an increase in binding capacity for TXA2.

scholarly journals Synthetic lipopeptide Pam3CysSer(Lys)4 is an effective activator of human platelets

1994 ◽  
Vol 266 (6) ◽  
pp. C1684-C1691 ◽  
Author(s):  
M. Berg ◽  
S. Offermanns ◽  
R. Seifert ◽  
G. Schultz
Keyword(s):  
Calcium Concentration ◽  
Cytosolic Calcium ◽  
Human Platelets ◽  
Cellular Effects ◽  
Prostacyclin Receptor ◽  
Serotonin Secretion ◽  
Peptide Moiety ◽  
Lipid Moiety ◽  
Molecular Masses ◽  
Aggregation Of Platelets

Lipopeptide analogues of the NH2-terminus of bacterial lipoprotein are known to induce activation of macrophages, neutrophils, and lymphocytes. We studied the effect of the lipopeptide N-palmitoyl-S-[2,3-bis(palmitoyloxy)-(2RS)-propyl]-(R)-cysteinyl-( S)-seryl-(S)-lysyl-(S)-lysyl-(S)-lysyl-(S)-lysine [Pam3CysSer(Lys)4] on several functions of human platelets. Pam3CysSer(Lys)4 led to the aggregation of platelets and induced the secretion of serotonin with an effectiveness similar to thrombin. These cellular effects of Pam3CysSer(Lys)4 were concentration dependent, being half maximal at 2-3 microM and maximal at 10-30 microM. Another lipopeptide also induced platelet aggregation and serotonin secretion but was less potent and less effective than Pam3CysSer(Lys)4. The lipid moiety and the peptide moiety of Pam3CysSer(Lys)4 alone were without any effect. Lipopeptides also stimulated tyrosine phosphorylation of several proteins with molecular masses similar to those found to be tyrosine phosphorylated in response to thrombin, and Pam3CysSer(Lys)4 led to an increase in the cytosolic calcium concentration. All studied responses of platelets to lipopeptides were inhibited by the prostacyclin receptor agonist cicaprost. Taken together, our data show that lipopeptides are effective activators of human platelets and that this activation is susceptible to the action of physiological platelet inhibitors.

scholarly journals Orientia tsutsugamushi Inhibits Apoptosis of Macrophages by Retarding Intracellular Calcium Release

2002 ◽  
Vol 70 (8) ◽  
pp. 4692-4696 ◽  
Author(s):  
Mee-Kyung Kim ◽  
Seung-Yong Seong ◽  
Ju-Young Seoh ◽  
Tae-Hee Han ◽  
Hyeon-Je Song ◽  
...  
Keyword(s):  
Intracellular Calcium ◽  
Calcium Concentration ◽  
Calcium Release ◽  
Cytosolic Calcium ◽  
Orientia Tsutsugamushi ◽  
Cytosolic Calcium Concentration ◽  
Infected Cells ◽  
Intracellular Calcium Release ◽  
Calcium Redistribution ◽  
In Cells

ABSTRACT Orientia tsutsugamushi shows both pro- and antiapoptotic activities in infected vertebrate cells. Apoptosis of THP-1 cells induced by beauvericin was inhibited by O. tsutsugamushi infection. Beauvericin-induced calcium redistribution was significantly reduced and retarded in cells infected with O. tsutsugamushi. Antiapoptotic activities of O. tsutsugamushi in infected cells are most probably due to inhibition of the increase in the cytosolic calcium concentration.

Fast determination of calcium concentration in the internal tissues of a single seed using laser-induced breakdown spectroscopy

2016 ◽  
Vol 8 (37) ◽  
pp. 6705-6710 ◽  
Author(s):  
Pengcheng Han ◽  
Daming Dong ◽  
Xiaofan Du ◽  
Leizi Jiao ◽  
Xiande Zhao
Keyword(s):  
High Precision ◽  
Calcium Concentration ◽  
Seed Vigor ◽  
Laser Induced Breakdown Spectroscopy ◽  
Fast Determination ◽  
Breakdown Spectroscopy ◽  
Single Seed ◽  
Small Influence ◽  
Laser Induced Breakdown

Laser-induced breakdown spectroscopy was used for the fast determination of calcium concentration in the internal tissues of a single seed. Compared with conventional methods, LIBS had obvious advantages, such as a little analysis spot, little ablation, high precision, and small influence on the seed vigor.

scholarly journals Protection against hydrogen peroxide cytotoxicity in Rat-1 fibroblasts provided by the oncoprotein Bcl-2: maintenance of calcium homoeostasis is secondary to the effect of Bcl-2 on cellular glutathione

1999 ◽  
Vol 340 (1) ◽  
pp. 291-297 ◽  
Author(s):  
Matthäus M. RIMPLER ◽  
Ursula RAUEN ◽  
Thorsten SCHMIDT ◽  
Tarik MÖRÖY ◽  
Herbert DE GROOT
Keyword(s):  
Cell Death ◽  
Calcium Concentration ◽  
Cell Injury ◽  
Cytosolic Calcium ◽  
Glutathione Metabolism ◽  
Transfected Cells ◽  
Cytosolic Calcium Concentration ◽  
Glutathione Status ◽  
Calcium Elevation ◽  
Reduced State

The oncoprotein Bcl-2 protects cells against apoptosis, but the exact molecular mechanism that underlies this function has not yet been identified. Studying H2O2-induced cell injury in Rat-1 fibroblast cells, we observed that Bcl-2 had a protective effect against the increase in cytosolic calcium concentration and subsequent cell death. Furthermore, overexpression of Bcl-2 resulted in an alteration of cellular glutathione status: the total amount of cellular glutathione was increased by about 60% and the redox potential of the cellular glutathione pool was maintained in a more reduced state during H2O2 exposure compared with non-Bcl-2-expressing controls. In our cytotoxicity model, disruption of cellular glutathione homoeostasis closely correlated with the pathological elevation of cytosolic calcium concentration. Stabilization of the glutathione pool by Bcl-2, N-acetylcysteine or glucose delayed the cytosolic calcium increase and subsequent cell death, whereas depletion of glutathione by DL-buthionine-(S,R)-sulphoximine, sensitized Bcl-2-transfected cells towards cytosolic calcium increase and cell death. We therefore suggest that the protection exerted by Bcl-2 against H2O2-induced cytosolic calcium elevation and subsequent cell death is secondary to its effect on the cellular glutathione metabolism.

TRAVELLING CALCIUM WAVES IN SYSTEMS WITH NON-DIFFUSING BUFFERS

2008 ◽  
Vol 18 (06) ◽  
pp. 883-912 ◽  
Author(s):  
BOGDAN KAZMIERCZAK ◽  
VITALY VOLPERT
Keyword(s):  
Structural Stability ◽  
Diffusion Coefficients ◽  
Calcium Concentration ◽  
Travelling Waves ◽  
Cytosolic Calcium ◽  
Calcium Waves ◽  
Cytosolic Calcium Concentration

The existence and structural stability of travelling waves of systems of the free cytosolic calcium concentration in the presence of immobile buffers are studied. The proof is carried out by passing to zero with the diffusion coefficients of buffers. Thus, its method is different from Ref. 13 where the existence is proved straightforwardly.

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