The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform
N. Himmelreich - One of the best experts on this subject based on the ideXlab platform.
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α-Latrotoxin affects mitochondrial potential and synaptic vesicle Proton Gradient of nerve terminals
Neurochemistry international, 2007Co-Authors: A. S. Tarasenko, L. G. Storchak, N. HimmelreichAbstract:Abstract Ca 2+ -independent [ 3 H]GABA release induced by α-latrotoxin was found to consist of two sequential processes: a fast initial release realized via exocytosis and more delayed outflow through the plasma membrane GABA transporters [Linetska, M.V., Storchak, L.G., Tarasenko, A.S., Himmelreich, N.H., 2004. Involvement of membrane GABA transporters in α-latrotoxin-stimulated [ 3 H]GABA release. Neurochem. Int. 44, 303–312]. To characterize the toxin-stimulated events attributable to the transporter-mediated [ 3 H]GABA release from rat brain synaptosomes we studied the effect of α-latrotoxin on membrane potentials and generation of the synaptic vesicles Proton Gradient, using fluorescent dyes: potential-sensitive rhodamine 6G and pH-sensitive acridine orange. We revealed that α-latrotoxin induced a progressive dose-dependent depolarization of mitochondrial membrane potential and an irreversible run-down of the synaptic vesicle Proton Gradient. Both processes were insensitive to the presence of cadmium, a potent blocker of toxin-formed transmembrane pores, indicating that α-latrotoxin-induced disturbance of the plasma membrane permeability was not responsible to these effects. A gradual dissipation of the synaptic vesicle Proton Gradient closely coupled with lowering the vesicular GABA transporter activity results in a leakage of the neurotransmitter from synaptic vesicles to cytoplasm. As a consequence, there is an essential increase in GABA concentration in a soluble cytosolic pool that appears to be critical parameter for altering the mode of the plasma membrane GABA transporter operation from inward to outward. Thus, our data allow clarifying what cell processes underlain a recruitment of the plasma membrane transporter-mediated pathway in α-LTX-stimulated secretion.
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Effectiveness of extracellular lactate/pyruvate for sustaining synaptic vesicle Proton Gradient generation and vesicular accumulation of GABA.
Journal of neurochemistry, 2006Co-Authors: A. S. Tarasenko, L. G. Storchak, M. V. Linetska, N. HimmelreichAbstract:The effects of extracellular monocarboxylates pyruvate and lactate on membrane potentials, acidification and neurotransmitter filling of synaptic vesicles were investigated in experiments with rat brain synaptosomes using [3H]GABA and fluorescent dyes, potential-sensitive rhodamine 6G and pH-sensitive acridine orange. In experiments investigating accumulation of acridine orange in synaptic vesicles within the synaptosomes, monocarboxylates, similarly to glucose, ensured generation of the vesicle Proton Gradient by available and recycled vesicles, and pyruvate demonstrated the highest efficacy. An increase in the level of Proton Gradient correlated with enhanced accumulation of [3H]GABA in synaptic vesicles and resulted in enlarged exocytosis and attenuated the transporter-mediated [3H]GABA release. Pyruvate added to glucose-contained medium caused more active binding of rhodamine 6G by synaptosomes that reflected mitochondrial membrane hyperpolarization, and this intensification of nerve terminal energy metabolism resulted in an increase in total ATP content by ∼25%. Pyruvate also prolonged the state of metabolic competence of nerve terminal preparations, keeping the mitochondrial potential and synaptic vesicle Proton Gradient at steady levels over a long period of time. Thus, besides glucose, the extracellular monocarboxylates pyruvate and lactate can provide sufficient support of energy-dependent processes in isolated nerve terminals, allowing effective functioning of neurotransmitter release and reuptake systems.
Johann Lavaud - One of the best experts on this subject based on the ideXlab platform.
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in diatoms the transthylakoid Proton Gradient regulates the photoprotective non photochemical fluorescence quenching beyond its control on the xanthophyll cycle
Plant and Cell Physiology, 2006Co-Authors: Johann Lavaud, Peter G. KrothAbstract:In diatoms, the non-photochemical fluorescence quenching (NPQ) regulates photosynthesis during light fluctuations. NPQ is associated with an enzymatic xanthophyll cycle (XC) which is controlled by the light-driven transthylakoid Proton Gradient (delta pH). In this report, special illumination conditions and chemicals were used to perturb the kinetics of the delta pH build-up, of the XC and of NPQ. We found that the delta pH-related acidification of the lumen is also needed for NPQ to develop by switching the xanthophylls to an 'activated' state, probably via the Protonation of light-harvesting antenna proteins. It confirms the NPQ model previously proposed for diatoms.
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In Diatoms, the Transthylakoid Proton Gradient Regulates the Photoprotective Non-photochemical Fluorescence Quenching Beyond its Control on the Xanthophyll Cycle
Plant and Cell Physiology, 2006Co-Authors: Johann Lavaud, Peter G. KrothAbstract:In diatoms, the non-photochemical fluorescence quenching (NPQ) regulates photosynthesis during light fluctuations. NPQ is associated with an enzymatic xanthophyll cycle (XC) which is controlled by the light-driven transthylakoid Proton Gradient (ΔpH). In this report, special illumination conditions and chemicals were used to perturb the kinetics of the ΔpH build-up, of the XC and of NPQ. We found that the ΔpH-related acidification of the lumen is also needed for NPQ to develop by switching the xanthophylls to an ‘activated’ state, probably via the Protonation of light-harvesting antenna proteins. It confirms the NPQ model previously proposed for diatoms.
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In diatoms, a transthylakoid Proton Gradient alone is not sufficient to induce a non-photochemical fluorescence quenching.
FEBS Letters, 2002Co-Authors: Johann Lavaud, Bernard Rousseau, Anne-lise EtienneAbstract:Non-photochemical fluorescence quenching (NPQ) in diatoms is associated with a xanthophyll cycle involving diadinoxanthin (DD) and its de-epoxidized form, diatoxanthin (DT). In higher plants, an obligatory role of de-epoxidized xanthophylls in NPQ remains controversial and the presence of a transthylakoid Proton Gradient (ΔpH) alone may induce NPQ. We used inhibitors to alter the amplitude of ΔpH and/or DD de-epoxidation, and coupled NPQ. No ΔpH-dependent quenching was detected in the absence of DT. In diatoms, both ΔpH and DT are required for NPQ. The binding of DT to Protonated antenna sites could be obligatory for energy dissipation.
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In diatoms, a transthylakoid Proton Gradient alone is not sufficient to induce a non-photochemical fluorescence quenching.
FEBS letters, 2002Co-Authors: Johann Lavaud, Bernard Rousseau, Anne-lise EtienneAbstract:Non-photochemical fluorescence quenching (NPQ) in diatoms is associated with a xanthophyll cycle involving diadinoxanthin (DD) and its de-epoxidized form, diatoxanthin (DT). In higher plants, an obligatory role of de-epoxidized xanthophylls in NPQ remains controversial and the presence of a transthylakoid Proton Gradient (DeltapH) alone may induce NPQ. We used inhibitors to alter the amplitude of DeltapH and/or DD de-epoxidation, and coupled NPQ. No DeltapH-dependent quenching was detected in the absence of DT. In diatoms, both DeltapH and DT are required for NPQ. The binding of DT to Protonated antenna sites could be obligatory for energy dissipation.
A. S. Tarasenko - One of the best experts on this subject based on the ideXlab platform.
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α-Latrotoxin affects mitochondrial potential and synaptic vesicle Proton Gradient of nerve terminals
Neurochemistry international, 2007Co-Authors: A. S. Tarasenko, L. G. Storchak, N. HimmelreichAbstract:Abstract Ca 2+ -independent [ 3 H]GABA release induced by α-latrotoxin was found to consist of two sequential processes: a fast initial release realized via exocytosis and more delayed outflow through the plasma membrane GABA transporters [Linetska, M.V., Storchak, L.G., Tarasenko, A.S., Himmelreich, N.H., 2004. Involvement of membrane GABA transporters in α-latrotoxin-stimulated [ 3 H]GABA release. Neurochem. Int. 44, 303–312]. To characterize the toxin-stimulated events attributable to the transporter-mediated [ 3 H]GABA release from rat brain synaptosomes we studied the effect of α-latrotoxin on membrane potentials and generation of the synaptic vesicles Proton Gradient, using fluorescent dyes: potential-sensitive rhodamine 6G and pH-sensitive acridine orange. We revealed that α-latrotoxin induced a progressive dose-dependent depolarization of mitochondrial membrane potential and an irreversible run-down of the synaptic vesicle Proton Gradient. Both processes were insensitive to the presence of cadmium, a potent blocker of toxin-formed transmembrane pores, indicating that α-latrotoxin-induced disturbance of the plasma membrane permeability was not responsible to these effects. A gradual dissipation of the synaptic vesicle Proton Gradient closely coupled with lowering the vesicular GABA transporter activity results in a leakage of the neurotransmitter from synaptic vesicles to cytoplasm. As a consequence, there is an essential increase in GABA concentration in a soluble cytosolic pool that appears to be critical parameter for altering the mode of the plasma membrane GABA transporter operation from inward to outward. Thus, our data allow clarifying what cell processes underlain a recruitment of the plasma membrane transporter-mediated pathway in α-LTX-stimulated secretion.
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Effectiveness of extracellular lactate/pyruvate for sustaining synaptic vesicle Proton Gradient generation and vesicular accumulation of GABA.
Journal of neurochemistry, 2006Co-Authors: A. S. Tarasenko, L. G. Storchak, M. V. Linetska, N. HimmelreichAbstract:The effects of extracellular monocarboxylates pyruvate and lactate on membrane potentials, acidification and neurotransmitter filling of synaptic vesicles were investigated in experiments with rat brain synaptosomes using [3H]GABA and fluorescent dyes, potential-sensitive rhodamine 6G and pH-sensitive acridine orange. In experiments investigating accumulation of acridine orange in synaptic vesicles within the synaptosomes, monocarboxylates, similarly to glucose, ensured generation of the vesicle Proton Gradient by available and recycled vesicles, and pyruvate demonstrated the highest efficacy. An increase in the level of Proton Gradient correlated with enhanced accumulation of [3H]GABA in synaptic vesicles and resulted in enlarged exocytosis and attenuated the transporter-mediated [3H]GABA release. Pyruvate added to glucose-contained medium caused more active binding of rhodamine 6G by synaptosomes that reflected mitochondrial membrane hyperpolarization, and this intensification of nerve terminal energy metabolism resulted in an increase in total ATP content by ∼25%. Pyruvate also prolonged the state of metabolic competence of nerve terminal preparations, keeping the mitochondrial potential and synaptic vesicle Proton Gradient at steady levels over a long period of time. Thus, besides glucose, the extracellular monocarboxylates pyruvate and lactate can provide sufficient support of energy-dependent processes in isolated nerve terminals, allowing effective functioning of neurotransmitter release and reuptake systems.
Peter G. Kroth - One of the best experts on this subject based on the ideXlab platform.
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in diatoms the transthylakoid Proton Gradient regulates the photoprotective non photochemical fluorescence quenching beyond its control on the xanthophyll cycle
Plant and Cell Physiology, 2006Co-Authors: Johann Lavaud, Peter G. KrothAbstract:In diatoms, the non-photochemical fluorescence quenching (NPQ) regulates photosynthesis during light fluctuations. NPQ is associated with an enzymatic xanthophyll cycle (XC) which is controlled by the light-driven transthylakoid Proton Gradient (delta pH). In this report, special illumination conditions and chemicals were used to perturb the kinetics of the delta pH build-up, of the XC and of NPQ. We found that the delta pH-related acidification of the lumen is also needed for NPQ to develop by switching the xanthophylls to an 'activated' state, probably via the Protonation of light-harvesting antenna proteins. It confirms the NPQ model previously proposed for diatoms.
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In Diatoms, the Transthylakoid Proton Gradient Regulates the Photoprotective Non-photochemical Fluorescence Quenching Beyond its Control on the Xanthophyll Cycle
Plant and Cell Physiology, 2006Co-Authors: Johann Lavaud, Peter G. KrothAbstract:In diatoms, the non-photochemical fluorescence quenching (NPQ) regulates photosynthesis during light fluctuations. NPQ is associated with an enzymatic xanthophyll cycle (XC) which is controlled by the light-driven transthylakoid Proton Gradient (ΔpH). In this report, special illumination conditions and chemicals were used to perturb the kinetics of the ΔpH build-up, of the XC and of NPQ. We found that the ΔpH-related acidification of the lumen is also needed for NPQ to develop by switching the xanthophylls to an ‘activated’ state, probably via the Protonation of light-harvesting antenna proteins. It confirms the NPQ model previously proposed for diatoms.
L. G. Storchak - One of the best experts on this subject based on the ideXlab platform.
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α-Latrotoxin affects mitochondrial potential and synaptic vesicle Proton Gradient of nerve terminals
Neurochemistry international, 2007Co-Authors: A. S. Tarasenko, L. G. Storchak, N. HimmelreichAbstract:Abstract Ca 2+ -independent [ 3 H]GABA release induced by α-latrotoxin was found to consist of two sequential processes: a fast initial release realized via exocytosis and more delayed outflow through the plasma membrane GABA transporters [Linetska, M.V., Storchak, L.G., Tarasenko, A.S., Himmelreich, N.H., 2004. Involvement of membrane GABA transporters in α-latrotoxin-stimulated [ 3 H]GABA release. Neurochem. Int. 44, 303–312]. To characterize the toxin-stimulated events attributable to the transporter-mediated [ 3 H]GABA release from rat brain synaptosomes we studied the effect of α-latrotoxin on membrane potentials and generation of the synaptic vesicles Proton Gradient, using fluorescent dyes: potential-sensitive rhodamine 6G and pH-sensitive acridine orange. We revealed that α-latrotoxin induced a progressive dose-dependent depolarization of mitochondrial membrane potential and an irreversible run-down of the synaptic vesicle Proton Gradient. Both processes were insensitive to the presence of cadmium, a potent blocker of toxin-formed transmembrane pores, indicating that α-latrotoxin-induced disturbance of the plasma membrane permeability was not responsible to these effects. A gradual dissipation of the synaptic vesicle Proton Gradient closely coupled with lowering the vesicular GABA transporter activity results in a leakage of the neurotransmitter from synaptic vesicles to cytoplasm. As a consequence, there is an essential increase in GABA concentration in a soluble cytosolic pool that appears to be critical parameter for altering the mode of the plasma membrane GABA transporter operation from inward to outward. Thus, our data allow clarifying what cell processes underlain a recruitment of the plasma membrane transporter-mediated pathway in α-LTX-stimulated secretion.
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Effectiveness of extracellular lactate/pyruvate for sustaining synaptic vesicle Proton Gradient generation and vesicular accumulation of GABA.
Journal of neurochemistry, 2006Co-Authors: A. S. Tarasenko, L. G. Storchak, M. V. Linetska, N. HimmelreichAbstract:The effects of extracellular monocarboxylates pyruvate and lactate on membrane potentials, acidification and neurotransmitter filling of synaptic vesicles were investigated in experiments with rat brain synaptosomes using [3H]GABA and fluorescent dyes, potential-sensitive rhodamine 6G and pH-sensitive acridine orange. In experiments investigating accumulation of acridine orange in synaptic vesicles within the synaptosomes, monocarboxylates, similarly to glucose, ensured generation of the vesicle Proton Gradient by available and recycled vesicles, and pyruvate demonstrated the highest efficacy. An increase in the level of Proton Gradient correlated with enhanced accumulation of [3H]GABA in synaptic vesicles and resulted in enlarged exocytosis and attenuated the transporter-mediated [3H]GABA release. Pyruvate added to glucose-contained medium caused more active binding of rhodamine 6G by synaptosomes that reflected mitochondrial membrane hyperpolarization, and this intensification of nerve terminal energy metabolism resulted in an increase in total ATP content by ∼25%. Pyruvate also prolonged the state of metabolic competence of nerve terminal preparations, keeping the mitochondrial potential and synaptic vesicle Proton Gradient at steady levels over a long period of time. Thus, besides glucose, the extracellular monocarboxylates pyruvate and lactate can provide sufficient support of energy-dependent processes in isolated nerve terminals, allowing effective functioning of neurotransmitter release and reuptake systems.
