The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform
Andrew G Ewing - One of the best experts on this subject based on the ideXlab platform.
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electrochemical detection of reverse transport from Planorbis giant dopamine neuron
Methods in Enzymology, 1998Co-Authors: Brian B Anderson, Andrew G Ewing, David SulzerAbstract:Publisher Summary This chapter highlights how studies of the giant dopamine neuron (GDN) located in the left pedal ganglion of the pond snail Planorbis corneus have provided direct demonstration of reverse transport from a neuron in real time. The GDN is advantageous for these studies because it has nomifensine-sensitive plasma membrane dopamine (DA) uptake, reserpine-sensitive vesicular DA uptake, it metabolizes DA to dihydroxyphenylacetic acid, and lacks ascorbic acid, facilitating the unambiguous amperometric detection of DA. Exocytic quantal release events can easily be distinguished from release by reverse transport using carbon fiber electrodes. The large size of the neuron allows the estimation of cytosolic levels of DA with intracellular carbon electrodes. The large size of the cell, the presence of the DA uptake system, and presence of many synaptic vesicles provides an enormous transmitter pool, proving the means to detect reverse transport from a single cell.
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electrochemical monitoring of bursting exocytotic events from the giant dopamine neuron of Planorbis corneus
Brain Research, 1996Co-Authors: Guangyao Chen, David A Gutman, Susan E Zerby, Andrew G EwingAbstract:We have discovered a neuronal system that fires bursting exocytotic events. In the giant dopamine neuron of the fresh water snail Planorbis corneus, bursting exocytotic events are evoked following in situ stimulation with elevated potassium. Amperometric detection using carbon fiber microelectrodes, which provides high temporal resolution, has been used to record exocytotic events released from the neuron. Evaluation of the time interval between consecutive exocytotic events (inter-spike interval) recorded from about 80% of the neurons reveals the occurrence of distinct bursting patterns defined by transients having an equal interval among them. Statistical analysis of these bursting exocytotic events shows three distinct distributions of inter-spike intervals with mid points occurring at 5, 22 and 45 ms. This bursting release behavior is not observed from cultured pheochromocytoma cells although they show calcium-dependent exocytosis following in situ stimulation with elevated potassium. Our data appear to indicate that the Planorbis dopamine neuron in vivo is actively involved in specific modes of neural communication and may represent an important phenomenon in understanding single cell activities.
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observation and quantitation of exocytosis from the cell body of a fully developed neuron in Planorbis corneus
The Journal of Neuroscience, 1995Co-Authors: Guangyao Chen, Peter F Gavin, Guoan Luo, Andrew G EwingAbstract:We have discovered a neuronal system that releases neurotransmitter via exocytosis from the cell body. In the large dopamine cell of the pond snail Planorbis corneus, depolarization induces rhythmic release of dopamine from the cell body. When a stimulant is applied extracellularly or intracellularly in situ to the cell body, transient dopamine concentration packets that appear in a bursting pattern are observed. Dopamine release is calcium dependent and release is on the time scale expected for exocytosis (2 to 4 msec rise times). Quantitation of individual events reveals an average of 818,000 molecules per exocytotic event. As many as 89,000 individual exocytotic events have been observed following a single stimulation of one cell. Neurotransmitter exocytosis from the neuronal cell body appears to represent an alternative form of neurocommunication to synaptic transmission.
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amphetamine redistributes dopamine from synaptic vesicles to the cytosol and promotes reverse transport
The Journal of Neuroscience, 1995Co-Authors: David Sulzer, Stephen Rayport, Takung Chen, H Kristensen, Andrew G EwingAbstract:Whether amphetamine acts principally at the plasma membrane or at synaptic vesicles is controversial. We find that d-amphetamine injection into the Planorbis giant dopamine neuron causes robust dopamine release, demonstrating that specific amphetamine uptake is not required. Arguing for action at vesicles, whole-cell capillary electrophoresis of single Planorbis dopamine neurons shows that amphetamine reduces vesicular dopamine, while amphetamine reduces quantal dopamine release from PC12 cells by > 50% per vesicle. Intracellular injection of dopamine into the Planorbis dopamine neuron produces rapid nomifensine-sensitive release, showing that an increased substrate concentration gradient is sufficient to induce release. These experiments indicate that amphetamine acts at the vesicular level where it redistributes dopamine to the cytosol, promoting reverse transport, and dopamine release.
David Sulzer - One of the best experts on this subject based on the ideXlab platform.
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electrochemical detection of reverse transport from Planorbis giant dopamine neuron
Methods in Enzymology, 1998Co-Authors: Brian B Anderson, Andrew G Ewing, David SulzerAbstract:Publisher Summary This chapter highlights how studies of the giant dopamine neuron (GDN) located in the left pedal ganglion of the pond snail Planorbis corneus have provided direct demonstration of reverse transport from a neuron in real time. The GDN is advantageous for these studies because it has nomifensine-sensitive plasma membrane dopamine (DA) uptake, reserpine-sensitive vesicular DA uptake, it metabolizes DA to dihydroxyphenylacetic acid, and lacks ascorbic acid, facilitating the unambiguous amperometric detection of DA. Exocytic quantal release events can easily be distinguished from release by reverse transport using carbon fiber electrodes. The large size of the neuron allows the estimation of cytosolic levels of DA with intracellular carbon electrodes. The large size of the cell, the presence of the DA uptake system, and presence of many synaptic vesicles provides an enormous transmitter pool, proving the means to detect reverse transport from a single cell.
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amphetamine redistributes dopamine from synaptic vesicles to the cytosol and promotes reverse transport
The Journal of Neuroscience, 1995Co-Authors: David Sulzer, Stephen Rayport, Takung Chen, H Kristensen, Andrew G EwingAbstract:Whether amphetamine acts principally at the plasma membrane or at synaptic vesicles is controversial. We find that d-amphetamine injection into the Planorbis giant dopamine neuron causes robust dopamine release, demonstrating that specific amphetamine uptake is not required. Arguing for action at vesicles, whole-cell capillary electrophoresis of single Planorbis dopamine neurons shows that amphetamine reduces vesicular dopamine, while amphetamine reduces quantal dopamine release from PC12 cells by > 50% per vesicle. Intracellular injection of dopamine into the Planorbis dopamine neuron produces rapid nomifensine-sensitive release, showing that an increased substrate concentration gradient is sufficient to induce release. These experiments indicate that amphetamine acts at the vesicular level where it redistributes dopamine to the cytosol, promoting reverse transport, and dopamine release.
Yuri I. Arshavsky - One of the best experts on this subject based on the ideXlab platform.
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Defense reaction in the pond snail Planorbis corneus. III. Response to input from statocysts.
Journal of neurophysiology, 1994Co-Authors: Yuri I. Arshavsky, Yu. V. Panchin, T G Deliagina, G N Orlovsky, I. L. Okshtein, Lyudmila B. PopovaAbstract:1. In the intact pond snail Planorbis corneus, a rapid tilt in any plane evoked a defense reaction consisting of a fast movement of the shell towards the head, shortening of the foot, inhibition of locomotion and of rhythmical feeding movements. This reaction was similar to the first phase of the general defense reaction of Planorbis to cutaneous stimulation. 2. A method has been developed for inclination of the isolated CNS in space (up to 90 degrees) and simultaneous intracellular recordings from different neurons. 3. The statocyst receptor cells (SRCs) responded both phasically and tonically to the tilt. The SRCs differ in their spatial zones of sensitivity. 4. Essential manifestations of the defense reaction to the input from statocysts could be observed in the in vitro preparation of the CNS isolated with statocysts. Both tilting of the CNS and electrical stimulation of individual SRCs elicited an excitatory response in numerous neurons from different ganglia, including motor neurons (MNs) of the columellar muscle. This response was of "all-or-none" nature, and could be evoked by electrical stimulation of any SRC. The response was followed by a long (10-20 s) period of refractoriness. 5. Activation of SRCs resulted also in excitation of the giant dopaminergic cell in the left pedal ganglion (related to the control of respiration), in inhibition of the feeding rhythm generator, and in inhibition of the pedal neurons responsible for activation of the ciliary locomotor system. 6. Combined stimulation of two inputs able to evoke a defense reaction, i.e., those from the statocyst and from cutaneous nerve, revealed a strong interdependence of their central effects.(ABSTRACT TRUNCATED AT 250 WORDS)
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defense reaction in the pond snail Planorbis corneus ii central pattern generator
Journal of Neurophysiology, 1994Co-Authors: Yuri I. Arshavsky, Yu. V. Panchin, T G Deliagina, G N Orlovsky, I. L. Okshtein, L B PopovaAbstract:1. In the isolated CNS of the pond snail Planorbis corneus, spontaneous bursts of activity in the motor neurons (MNs) supplying the columellar muscle were occasionally observed. The biphasic pattern of this activity, with a shorter (3-5 s) initial burst and longer (20-40 s) subsequent burst, was similar to that of the motor output during the general ("whole-body") defense reaction. In preparations consisting of the CNS isolated with the columellar muscle or with the lung, spontaneous biphasic contractions of the muscle as well as openings of the pneumostome with a temporal pattern characteristic of the defense reaction were observed. These findings demonstrated that the efferent pattern of the defense reaction in the snail is, to a large extent, produced by a special neuronal mechanism (the central pattern generator, CPG) triggered by the sensory input, rather than generated by ongoing processing of sensory input. The CPG consists of two components responsible for generation of two phases of the defense reaction. A characteristic feature of the CPG is that the magnitude of its response depends in a graded fashion on the strength of the initial stimulus. 2. In the pleural ganglia there are at least two electrically connected interneurons (DRN1s) that play an important role in generation of the first phase of the defense reaction. Processes of the DRN1s form a ring passing through all (except pedal and buccal) ganglia. The DRN1s received an excitatory input when a peripheral nerve was stimulated. They generated action potentials of long (0.2-2 s) duration. The DRN1 from the right ganglion was studied in more detail.(ABSTRACT TRUNCATED AT 250 WORDS)
Christian Selbach - One of the best experts on this subject based on the ideXlab platform.
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Small but diverse: larval trematode communities in the small freshwater planorbids Gyraulus albus and Segmentina nitida (Gastropoda: Pulmonata) from the Ruhr River, Germany
Parasitology Research, 2018Co-Authors: J. Schwelm, Miroslava Soldánová, Bernd Sures, T. Vyhlídalová, Christian SelbachAbstract:In contrast to the well-studied trematode fauna of lymnaeid snails, only little is known about the role of small planorbid snails as first intermediate hosts for trematodes in temperate freshwater systems. This study aims at closing this gap by assessing the diversity and composition of larval trematode communities in Gyraulus albus and Segmentina nitida in a Central European reservoir system, and by providing an updated comprehensive review of the published trematode records of these snail hosts. A total of 3691 planorbid snails (3270 G. albus ; 421 S. nitida ) was collected in three consecutive years from four reservoirs of the River Ruhr catchment area in Germany. Gyraulus albus showed a higher overall trematode prevalence (11.7%) and more diverse trematode fauna (12 species) compared to S. nitida , which harboured three species and showed a lower trematode prevalence (1.7%). Altogether, 13 trematode species belonging to four families were identified in both hosts. Seven trematode species encountered in this study represent novel records for these hosts, and/or constitute first records of these larval stages from Germany. Trematode component communities in G. albus were stable across seasons and years, indicating excellent conditions for trematodes in this snail host and the continuous presence of the final hosts of the most dominant trematode species. Overall, this study reveals the importance of small planorbid snails, in particular G. albus , as first intermediate hosts for a species-rich trematode fauna in European freshwater systems, and highlights the parasites’ contribution to the ecosystem’s biodiversity.
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morphological and molecular data for larval stages of four species of petasiger dietz 1909 digenea echinostomatidae with an updated key to the known cercariae from the palaearctic
Systematic Parasitology, 2014Co-Authors: Christian Selbach, Miroslava Soldánová, Simona Georgieva, Aneta Kostadinova, Martin Kalbe, Bernd SuresAbstract:Large-tailed echinostomatid cercariae of the genus Petasiger Dietz, 1909 (Digenea: Echinostomatidae) from the planorbid snails Gyraulus albus (Muller) and Planorbis Planorbis (L.) collected in Germany and the Czech Republic and metacercariae from Gasterosteus aculeatus L. (Gasterosteiformes: Gasterosteidae) collected in Canada are characterised morphologically and molecularly. The rediae, cercariae and metacercariae are described in detail and compared with the existing data on the larval stages of Petasiger spp. Comparative molecular analyses using 28S rDNA and nad1 mitochondrial sequences supported the distinct status of four species of Petasiger. Molecular and morphological evidence for their distinction and an updated key to the known large-tailed cercariae of Petasiger from the Palaearctic are provided.
Guangyao Chen - One of the best experts on this subject based on the ideXlab platform.
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electrochemical monitoring of bursting exocytotic events from the giant dopamine neuron of Planorbis corneus
Brain Research, 1996Co-Authors: Guangyao Chen, David A Gutman, Susan E Zerby, Andrew G EwingAbstract:We have discovered a neuronal system that fires bursting exocytotic events. In the giant dopamine neuron of the fresh water snail Planorbis corneus, bursting exocytotic events are evoked following in situ stimulation with elevated potassium. Amperometric detection using carbon fiber microelectrodes, which provides high temporal resolution, has been used to record exocytotic events released from the neuron. Evaluation of the time interval between consecutive exocytotic events (inter-spike interval) recorded from about 80% of the neurons reveals the occurrence of distinct bursting patterns defined by transients having an equal interval among them. Statistical analysis of these bursting exocytotic events shows three distinct distributions of inter-spike intervals with mid points occurring at 5, 22 and 45 ms. This bursting release behavior is not observed from cultured pheochromocytoma cells although they show calcium-dependent exocytosis following in situ stimulation with elevated potassium. Our data appear to indicate that the Planorbis dopamine neuron in vivo is actively involved in specific modes of neural communication and may represent an important phenomenon in understanding single cell activities.
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observation and quantitation of exocytosis from the cell body of a fully developed neuron in Planorbis corneus
The Journal of Neuroscience, 1995Co-Authors: Guangyao Chen, Peter F Gavin, Guoan Luo, Andrew G EwingAbstract:We have discovered a neuronal system that releases neurotransmitter via exocytosis from the cell body. In the large dopamine cell of the pond snail Planorbis corneus, depolarization induces rhythmic release of dopamine from the cell body. When a stimulant is applied extracellularly or intracellularly in situ to the cell body, transient dopamine concentration packets that appear in a bursting pattern are observed. Dopamine release is calcium dependent and release is on the time scale expected for exocytosis (2 to 4 msec rise times). Quantitation of individual events reveals an average of 818,000 molecules per exocytotic event. As many as 89,000 individual exocytotic events have been observed following a single stimulation of one cell. Neurotransmitter exocytosis from the neuronal cell body appears to represent an alternative form of neurocommunication to synaptic transmission.