Cytosolic acidification and γ-aminobutyric acid synthesis during the oxidative burst in isolated Asparagus sprengeri mesophyll cells

2001 ◽  
Vol 79 (4) ◽  
pp. 438-443
Author(s):  
David J Janzen ◽  
Lisa J Allen ◽  
Kennaway B MacGregor ◽  
Alan W Bown
Keyword(s):  
Oxidative Burst ◽  
Acid Synthesis ◽  
Aminobutyric Acid ◽  
Intracellular Acidification ◽  
Protein Amino Acid ◽  
Mesophyll Cells ◽  
Intracellular Ca ◽  
Gaba Accumulation ◽  
Gaba Synthesis ◽  
The Relationship

The four carbon, non-protein amino acid γ-aminobutyrate (GABA) accumulates rapidly in response to diverse stresses. Its synthesis is stimulated by increases in intracellular Ca2+ or H+ levels. The pathogen-induced oxidative burst is also associated with increases in Ca2+ and H+ levels. This study investigated the relationship between GABA synthesis and the oxidative burst. A Mas-7-induced consumption of oxygen in isolated Asparagus sprengeri Regel mesophyll cells was accompanied by rapid GABA synthesis. At pH 5.0, a 300% increase occurred within 16 min from 6.6 to 26.3 nmol GABA·106 cells–1. At pH 6.0, the increase was from 8.5 to 18.1 nmol GABA·106 cells–1. Mas-7 also stimulated rapid external alkalinization and intracellular acidification. Intracellular pH decreased 0.44 pH units at pH 5.0, and 0.21 pH units at pH 6.0. The Mas-7-induced oxidative burst, GABA synthesis, extracellular alkalinization, and intracellular acidification were all eliminated when lanthanum, a Ca2+ channel blocker, replaced Ca2+ in the incubation medium. The data demonstrate that GABA accumulation is associated with the oxidative burst, and results from the fluxes of H+ and Ca2+, which are known to accompany the oxidative burst. They are discussed in light of emerging data that indicate a role for GABA in plant cell to cell signaling.Key words: γ-aminobutyric acid, GABA, oxidative burst.

Cold-shock-stimulated γ-aminobutyric acid synthesis is mediated by an increase in cytosolic Ca2+, not by an increase in cytosolic H+

1997 ◽  
Vol 75 (3) ◽  
pp. 375-382 ◽  
Author(s):  
Ewa Cholewa ◽  
Alan W. Bown ◽  
Andrzej J. Cholewinski ◽  
Barry J. Shelp ◽  
Wayne A. Snedden
Keyword(s):  
Cold Shock ◽  
Signal Transduction Pathway ◽  
Acid Synthesis ◽  
Aminobutyric Acid ◽  
Decarboxylase Activity ◽  
Mesophyll Cells ◽  
Ph Optimum ◽  
Calmodulin Antagonist ◽  
Nonprotein Amino Acid

Synthesis of the nonprotein amino acid γ-aminobutyric acid is stimulated within minutes by diverse environmental factors. Synthesis (L-Glu + H+ – γ-aminobutyric acid + CO2) is catalysed by L-Glu decarboxylase, a cytosolic enzyme having an acidic pH optimum. This study uses isolated Asparagus sprengeri (Regel) mesophyll cells to investigate the possible role of Ca2+ in stimulated γ-aminobutyric acid synthesis. Abrupt cold shock (20 °C to 1 °C) stimulated γ-aminobutyric acid levels from 2.7 to 5.6 nmol/106 cells within 15 min. This 100% increase was reduced to 28% in the presence of the Ca2+ channel blocker lanthanum, and was significantly reduced by incubation with 1 mM of the calmodulin antagonist N-(6-aminohexyl)-5-chloro-1-naphthalene-sulfonamide. Incubation at 20 °C with 25 μM calcimycin, a Ca2+ ionophore, increased levels by 61% within 15 min. A fluorescent Ca2+ indicator demonstrated that cytosolic Ca2+ increased within 2 s of cold shock, followed by a return to initial levels within 25 s. In contrast, comparable experiments indicate a rapid and prolonged decrease in cytosolic H+. L-Glu decarboxylase isolated from asparagus cladophylls was stimulated 100% by addition of 500 μM Ca2+ and 200 nM calmodulin. This activity was reduced to control values by the calmodulin antagonist. Collectively, the data indicate that cold shock initiates a signal transduction pathway in which increased cytosolic Ca2+ stimulates calmodulin-dependent L-Glu decarboxylase activity and γ-aminobutyric acid synthesis. This mechanism appears independent of increased H+. Key words: cold shock, GABA, Ca2+, H+.

Mechanical stimulation, 4-aminobutyric acid (GABA) synthesis, and growth inhibition in soybean hypocotyl tissue

2000 ◽  
Vol 78 (1) ◽  
pp. 119-123
Author(s):  
Alan W Bown ◽  
Guijin Zhang
Keyword(s):  
Growth Inhibition ◽  
Mechanical Stimulation ◽  
Growth Increment ◽  
Aminobutyric Acid ◽  
Gaba A ◽  
Nonprotein Amino Acid ◽  
Gaba Accumulation ◽  
Gaba Synthesis ◽  
Hypocotyl Tissue ◽  
First Time

4-Aminobutyric acid (GABA), a ubiquitous four-carbon nonprotein, amino acid, is synthesized via glutamate decarboxylation. It accumulates in response to mechanical stimulation through the Ca2+/calmodulin activation of glutamate decarboxylase. In this study, dark- and light-grown soybean hypocotyl tissues were used to investigate the relationship between mechanical stimulation, GABA synthesis, and growth inhibition. Mechanical stimulation through stroking resulted in a 65% growth inhibition of dark- or light-grown tissue within 1 min. The 24-h growth increment was reduced by 50% or more. Growth inhibition was accompanied by rapid 4- and 10-fold increases in GABA levels in dark- and light-grown tissue, respectively. Treatment of tissue with exogenous GABA raised GABA levels approximately 6-fold, but did not inhibit growth. In addition, lanthanum or blue light treatment of dark-grown tissue reduced growth by over 60% with no increase in GABA levels. The data demonstrate for the first time, that GABA accumulation accompanies growth inhibition occurring in response to mechanical stimulation. However, GABA accumulation alone appears insufficient to cause growth inhibition.Key words: 4-aminobutyric acid, GABA, L-Glu decarboxylase, GAD, thigmomorphogenesis, mechanical stimulation.

scholarly journals Effect of components in homogeneous extraction suspensions of pea and sweet buckwheat on γ-aminobutyric acid synthesis

2019 ◽  
Vol 37 (No. 4) ◽  
pp. 292-300
Author(s):  
Yulong Huang ◽  
Na Chen ◽  
Fengxia Wang ◽  
Shen Song ◽  
Jie Guo ◽  
...  
Keyword(s):  
Raw Materials ◽  
Monosodium Glutamate ◽  
Acid Synthesis ◽  
Aminobutyric Acid ◽  
Homogeneous Fluid ◽  
Maximal Increase ◽  
Mixed Suspension ◽  
Composition Formula ◽  
Gaba Content ◽  
Gaba Synthesis

The effects of calcium chloride (CaCl2), vitamin B6 (VB6), and monosodium glutamate (MSG) on the synthesis of γ-aminobutyric acid (GABA) in the mixed homogeneous suspension of pea and sweet buckwheat (1:1 w/w) were investigated. The composition formula of raw materials in the homogeneous fluid for GABA synthesis was optimized via response surface methodology (RSM). The result showed that the increased content of GABA was dependent on the addition of CaCl2, VB6, and MSG to the mixed suspension. Box-Behnken design indicated that the optimal added components for GABA synthesis were: CaCl2 at a concentration of 0.85 mmol/l, VB6 at a concentration of 2.29 mmol/l, and MSG at a concentration of 2.83 mg/ml. Under optimal conditions, a maximal increase of GABA content (51.29 µg/ml) was obtained. Analysis of variance for the regression model suggested that the model can exactly predict GABA synthesis in the mixed homogeneous suspension.

Exogenous calcium chloride (CaCl2) promotes γ-aminobutyric acid (GABA) accumulation in fresh-cut pears

2021 ◽  
Vol 174 ◽  
pp. 111446
Author(s):  
Zongyu Chi ◽  
Yuqin Dai ◽  
Shifeng Cao ◽  
Yingying Wei ◽  
Xingfeng Shao ◽  
...  
Keyword(s):  
Calcium Chloride ◽  
Aminobutyric Acid ◽  
Gaba Accumulation ◽  
Exogenous Calcium ◽  
Fresh Cut

Excitability of primary afferents in feline spinal cord: taurine, homotaurine, and γ-aminobutyric acid compared

1982 ◽  
Vol 60 (6) ◽  
pp. 850-855 ◽  
Author(s):  
Radan Čapek ◽  
Barbara Esplin
Keyword(s):  
Primary Afferents ◽  
Aminobutyric Acid ◽  
Primary Afferent Depolarization ◽  
Conditioning Stimulation ◽  
Primary Afferent ◽  
Antagonistic Muscle ◽  
Consistent Change ◽  
Muscle Nerve ◽  
Gaba Synthesis ◽  
Stimulation Of

Effects of taurine and homotaurine (3-aminopropancsuIfonic acid), on excitability of primary afferents were compared with effects of γ-aminobutyric acid (GABA) in spinal unanaesthesized cats. Homotaurine and GABA, administered intravenously or topically, produced a marked increase in afferent excitability. Homotaurine was about 10 times more potent than GABA. Taurine (up to 2 mmol/kg i.v., or 10 mM topically) did not produce a consistent change in afferent excitability. The effect of homotaurine was antagonized by bicuculline or picrotoxin in doses which suppressed the primary afferent depolarization, as indicated by an increase of afferent excitability, evoked by conditioning stimulation of an antagonistic muscle nerve. Semicarbazidc, an inhibitor of GABA synthesis, did not attenuate the homotaurine-induced excitability changes of afferents while suppressing entirely the primary afferent depolarization. These findings suggest that homotaurine exerts a direct GABA-like action on feline primary afferents.

Oxidative burst and NO generation as initial response to ischemia in flow-adapted endothelial cells

2001 ◽  
Vol 280 (5) ◽  
pp. H2126-H2135 ◽  
Author(s):  
Yefim Manevich ◽  
Abu Al-Mehdi ◽  
Vladimir Muzykantov ◽  
Aron B. Fisher
Keyword(s):  
Endothelial Cells ◽  
Plasma Membrane ◽  
Oxidative Burst ◽  
Initial Response ◽  
Membrane Depolarization ◽  
No Synthase ◽  
Potential Production ◽  
Perfusion Chamber ◽  
Intracellular Ca ◽  
Static Conditions

Shear stress modulates endothelial physiology, yet the effect(s) of flow cessation is poorly understood. The initial metabolic responses of flow-adapted bovine pulmonary artery endothelial cells to the abrupt cessation of flow (simulated ischemia) was evaluated using a perfusion chamber designed for continuous spectroscopy. Plasma membrane potential, production of reactive O2 species (ROS), and intracellular Ca2+ and nitric oxide (NO) levels were measured with fluorescent probes. Within 15 s after flow cessation, flow-adapted cells, but not cells cultured under static conditions, showed plasma membrane depolarization and an oxidative burst with generation of ROS that was inhibited by diphenyleneiodonium. EGTA-inhibitable elevation of intracellular Ca2+ and NO were observed at ∼30 and 60 s after flow cessation, respectively. NO generation was decreased in the presence of inhibitors of NO synthase and calmodulin. Thus flow-adapted endothelial cells sense the altered hemodynamics associated with flow cessation and respond by plasma membrane depolarization, activation of NADPH oxidase, Ca2+ influx, and activation of Ca2+/calmodulin-dependent NO synthase. This signaling response is unrelated to cellular anoxia.

scholarly journals Accumulation γ-Aminobutyric Acid and Biogenic Amines in a Traditional Raw Milk Ewe’s Cheese

Foods ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 401 ◽  
Author(s):  
Rosanna Tofalo ◽  
Giorgia Perpetuini ◽  
Noemi Battistelli ◽  
Alessia Pepe ◽  
Andrea Ianni ◽  
...  
Keyword(s):  
Biogenic Amines ◽  
Raw Milk ◽  
Starter Cultures ◽  
Aminobutyric Acid ◽  
Microbial Composition ◽  
Qrt Pcr ◽  
A Value ◽  
Gaba Content ◽  
Gaba Accumulation ◽  
Polymerase Chain

The influence of calf (R1), kid (R2) and pig (R3) rennets on microbiota, biogenic amines (BAs) and γ-aminobutyric acid (GABA) accumulation in raw milk ewe’s cheeses was evaluated. Cheeses were investigated at different ripening times for their microbial composition, free amino acids (FAAs), BAs and GABA content. Moreover, the expression of tyrosine (tdc) and histidine (hdc) decarboxylases genes was evaluated by quantitative Real Time–Polymerase Chain Reaction (qRT-PCR). Microbial counts showed similar values in all samples. Pig rennet were cheeses were characterized by higher proteolysis and the highest values of BAs. The BAs detected were putrescine, cadaverine and tyramine, while histamine was absent. qRT-PCR confirmed this data, in fact hdc gene was not upregulated, while tdc gene expression increased over time in agreement with the increasing content of tyramine and the highest fold changes were detected in R3 cheeses. GABA showed the highest concentration in R2 cheeses reaching a value of 672 mg/kg. These results showed that the accumulation of BAs and GABA in Pecorino di Farindola is influenced by ripening time and type of coagulant. Further studies are required to develop starter cultures to reduce BAs content and improve health characteristics of raw milk ewe’s cheeses.

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