bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemoreception in gastropod molluscs: Electron microscopy of putative receptor cells
Authors: Davis W. J. , Matera Eugene M. 
Published: January 2005

AbstractScanning and transmission electron microscopy of the external surface of the gastropod mollusc Pleurobranchaea californica has revealed a new exteroreceptor, characterized by dense cilia (ca. 200/cell) that project from an intraepithelial soma and exhibit dilated, discoid‐shaped tips. The exteroreceptor is found in high densities (up to 5000/mm2) in areas of the body determined by behavioral assay to be chemosensitive, but nowhere else, suggesting that it is a chemoreceptor.
The effect of single giant interneuron lesions on wind‐evoked motor responses in the cockroach, Periplaneta americana
Authors: Westin Joanne , Ritzmann Roy E. 
Published: January 2005

AbstractIn order to determine the contribution of individual giant interneurons (GIs) to wind‐evoked motor outputs, responses were recorded from depressor and levator motor neurons in the cockroach Periplaneta americana to wind puffs of different directions. The depressor response was generally stronger to wind from the ipsilateral rear than to wind from the contralateral rear. The levator response was more variable but was more often stronger to wind from the contralateral rear than to wind from the ipsilateral rear. These results are as expected based on behavioral responses to wind puffs. (Camhi and Tom, 1978). The depressor response was nearly or totally abolished by severing the ipsilateral connective of the nerve cord but was little affected by severing the contralateral connective. The levator reponse was greatly reduced for some angles by severing the ipsilateral connective and for other angles by severing the contralateral connective. Blocking conduction in the ipsilateral GI 5 nearly or completely abolished the depressor response to wind from the ipsilateral rear. This is the first time that a GI has been shown to be necessary, not just sufficient, for a given motor output.
The identification and localization of a catecholamine in the motor neurons of the lobster cardiac ganglion
Authors: Ocorr Karen A. , Berlind Allan 
Published: January 2005

AbstractThe cardiac ganglion from Homarus americanus was investigated for the purpose of providing biochemical and histochemical information as to the identity of the neurotransmitter(s) utilized by this system. Three techniques were employed in this study: (1) the glyoxylic acid histofluorescence staining technique (GA), which showed fluorescence characteristic of catecholamines localized in the five motor neurons; (2) high‐voltage electrophoresis (HVE) in one dimension followed by ascending chromatography in the second dimension, which indicated incorporation of label from tritiated tyrosine into norepinephrine (NE) and small amounts of dopamine (DA); (3) high‐pressure liquid chromatography with electrochemical detection (HPLC/EC), which indicated the presence of endogenous norepinephrine.
Pure population of viable neurons from rabbit dorsal root ganglia, using gradients of percoll
Authors: Goldenberg S. S. S. , De Boni U. 
Published: January 2005

AbstractNonneuronal cells complicate the study of neurons in vitro. A pure population of viable neurons can be obtained easily using gradients of Percoll. For each experiment, 20 dorsal root ganglia (DRG) are minced, then sequentially dissociated in collagenase and trypsin, which digest all the intercellular connections. The dissociated tissue is separated first on the basis of density, creating an interphase fraction enriched in neurons and satellite cells, which are then further separated on the basis of size. The neurons, obtained in the final pellet, number approximately 50,000 (2500 per DRG), routinely exhibit a viability of over 80% initially and are of a purity of over 90%. The viability of the neurons is confirmed by the occurrence of neurite outgrowth in culture. Thus, a pure and viable neuronal population is obtained by a simple and rapid method.
Serotonin immunoreactive neurons in the central nervous system of an insect (Periplaneta americana)
Authors: Bishop Cynthia A. , O'shea Michael 
Published: January 2005

AbstractSerotonin‐like immunoreactivity was mapped in the central nervous system (CNS) of the cockroach, Periplaneta americana. Immunoreactive staining occured in every ganglion of the CNS. The largest numbers of immunoreactive somata were detected in the optic lobes and the brain, and lowest numbers in the first and second toracic ganglia. Dense stained fibers, ramifications, and varicosities were found in all ganglia, and numerous axon like processes occurred in all interganglionic connectives. Immunoreactive processes were not, however, detected in most of the peripherally projecting nerve roots. Processes were found only in roots of the suboesophageal ganglion and the tritocerebral lobes of the brain. A comparison of the map for serotonin immunoreactivity with one generated for the pentapeptide transmitter proctolin suggests that the two systems overlap only in the suboesophageal ganglion and the tritocerebrum. The amine and peptide may co‐occur in neurons in these regions. The serotonin immunoreactive system appeared significantly different from the octopaminergic system of the ventral nerve cord. Seventy‐two potentially identifiable immunoreactive cells were located in the cockroach CNS. Some of these may be suitable for physiological study of the functional role of serotonin.
Spiral waves of spreading depression in the isolated chicken retina
Authors: Gorelova N. A. , Bureš J. 
Published: January 2005

AbstractExistence of the theoretically predicted spiral waves of excitation in intact two‐dimensional networks of excitable elements has been experimentally confirmed in the isolated chicken retina. The preparation supports the waves of Leão's spreading depression (SD) the concentric propagation of which from the point of origin can be directly observed as a change of the optical properties of the retinal tissue. The propagation rate of 3.7 mm/min (35°C) decreased to 1.5 mm/min for SD waves elicited during relative refractory period. When a several‐mm long segment of the SD wave had been blocked by anodal polarization, the laterally opened ends of the wavefront started to spread after termination of polarization into the previously blocked tissue, gradually turning around and penetrating into the region recovering from the original SD. One or two simultaneously generated spiral waves of SD continued to rotate for several cycles. Spiral SD could also be elicited by punctiform cathodal polarization (1 mA) applied to the SD wave‐rear. Since the new SD wave could only spread into the recovering tissue it formed a laterally open wavefront, the free ends of which eventually turned around and started spiral SD. With continued reverberation the nucleus of the spiral SD wave gradually migrated across the retina until it approached an obstacle (e.g., pecten) which stopped further spiral propagation. Spiral SD waves were elicited in 31 retinal preparations and lasted for 4.5 cycles on the average. Average cycle duration was 4.7 min. Spontaneous spiral SD waves were observed in preparations incubated in Mg2+‐free media. The spiral SD waves in retina are compared with mathematical models of analogous phenomena. It is argued that spiral SD waves probably exist in the cerebral cortex of rats and account for generation of repetitive SD waves sometimes elicited by overlapping stimulation of two cortical regions.
Postsynaptic mechanism of withdrawal reflex sensitization in the snail
Authors: Balaban P. M. 
Published: January 2005

AbstractRepeated tactile stimulation of the skin evoked sensitization and subsequent habituation of a behavioral avoidance reaction of pneumstome closure in the land snail, Helix lucorum L. Spike responses in putative command neurons for avoidance behavior increased and subsequently decreased parallel to behavioral events. Decrease of spike responses in command neurons was due to decreased synaptic input evoked by repeated tactile stimulation. Intracellular investigation of the increase in the spike response in command neurons for pneumostome closure, which underlies behavioral sensitization, revealed a synpatically‐evoked, long‐lasting depolarization. No conductance changes during this depolarization were found, but neuronal excitability was altered.
Maintained depolarization of synaptic terminals facilitates nerve‐evoked transmitter release at a crayfish neuromuscular junction
Authors: Wojtowicz J. M. , Atwood H. L. 
Published: January 2005

AbstractPresynaptic and postsynaptic potentials were examined by intracellular recording at a crayfish neuromuscular junction. During normal synaptic transmission, the action potentials were recorded in the terminal region of the excitatory axon and postsynaptic responses were obtained in the muscle fibers. We found that it was possible to modify the synaptic transmission by applying depolarizing or hyperpolarizing currents through the presynaptic intracellular electrode. Typically, a 7 15 mV depolarization lasting longer than 50 msec leads to a large (500%) enhancement of transmitter release, even though the preterminal action potential is reduced in amplitude. Hyperpolarization increases the amplitude of the action potential, but slightly reduces the transmitter release. These results are different from those reported for other neuromuscular synapses and the squid giant synapse, but are similar in many respects to the results reported for several invertebrate central synapses. We conclude, first, that different synapses may have markedly different responses to conditioning by membrane polarization and, secondly, that maintained low‐level depolarization may induce a potentiated state in the nerve terminal, perhaps brought about by slow entry of calcium.
Influence of walking on swimmeret beating in the lobster Homarus gammarus
Authors: Cattaert D. , Clarac F. 
Published: January 2005

AbstractInfluence of walking on swimmeret beating in intact lobsters, Homarus gammarus, has been analyzed using a treadmill experimental device. Belt movement activates both leg stepping and swimmeret beating. The simultaneity of the onset of the two motor systems in this situation is demonstrated to be the result of a startle response initiated when the belt begins to move. This reaction consists of a non‐specific motor activity involving several antagonist postural and dynamic muscles. Abdominal extension and vigorous swimmeret beating are the main featurs of this reaction. The main characteristics of the swimmeret beating as defined by Davis (1969) has been observed here in sequences without walking. However during long walking sequences a very different swimmeret beating pattern occurs. It is suggested that this slow swimmeret beating is completely subordinate to the walking rhythm during sequences of absolute coordination. In more rapid swimmeret beating a relative coordination with leg stepping is very common. The functional meaning of this linkage between legs and swimmerets is discussed.
Axonal transport of [3H] GABA and [3H] glutamate in excitatory and inhibitory neurons innervating lobster exoskeletal musculature
Authors: Woodward William R. 
Published: January 2005

AbstractThis paper describes the results of intracellular injections of radiolabelled neurotransmitters and transmitter precursor substances, including glutamate, GABA, aspartate, octopamine, tyramine, tryptophan, and choline, into cell bodies of identified excitatory and inhibitory neurons innervating lobster extensor musculature. The distributions and identities of radioactive substances appearing in axons were examined at various times following injection and in vitro incubation. Injected GABA and glutamate were found in appreciable quantities in both excitatory and inhibitory axons and migrated down axons at an estimated rate of between 16 and 22 mm/day at 12° C, whereas the other substances tested were present in substantially smaller quantities and migrated at an estimated rate of less than 7.5 mm/day at 12° C. Injected GABA, D‐glutamate and L‐glutamate accumulated proximal to ligatures tied around nerves, whereas neither octopamine nor aspartate accumulated proximal to ligatures. Since GABA is the transmitter substance released by inhibitory neurons and L‐glutamate is thought to be released from excitatory nerve terminals, these results are consistent with the suggestion that amino acids serving as neurotransmitters are axonally transported. The specificity of axonal transport does not appear to be restricted to the cognate neurotransmitter, as indicated by the movement of L‐glutamate in inhibitory axons and GABA in excitatory axons and of D‐glutamate in both excitatory and inhibitory axons, but rather may be relaxed to include substances closely related to the neurotransmitter. Some restrictions, however, are apparently placed on axonal transport of small chaged molecules in these neurons in that other substances tested migrated down nerves at a considerably slower rate.
The possible role of “sibling neurite bias” in the coordination of neurite extension, branching, and survival
Authors: Smalheiser Neil R. , Crain Stanley M. 
Published: January 2005

AbstractIn this review we consider a novel mechanism, “sibling neurite bias,” which may explain aspects of the coordination of elongation, branching, and resorption among different neurites growing from the same neuronal cell body. In this model, growing neurites which incorporate structural precursors at higher rates would deplete the cellular pool of precursors available to their “sibling” neurites; neurites would compete for survival, but in addition they would bias each other's behavior during active growth. Evidence is reviewed that “sibling neurite bias” may contribute to the establishment and stabilization of specific neural connections. Specific examples examined include the loss of polyinnervation at the developing neuromuscular junction, contextual mapping in the retino‐tectal system, and selective neurite growth patterns and synaptic connections in nerve tissue culture model systems.
Central generation of swimming activity in the hydrozoan jellyfish Aequorea aequorea
Authors: Satterlie Richard A. 
Published: January 2005

AbstractSwimming in Aequorea is controlled by a network of electrically coupled neurons (swim motorneurons) located in the inner nerve ring. The network is made up of the largest neurons in the ring, up to 22 μm in diameter. Intracellular recordings from swim motorneurons reveal slow membrane potential oscillations and a superimposed barrage of synaptic “noise.” The synaptic noise, but not the slow oscillations, is eliminated in seawater containing an elevated Mg++ concentration. The swim motorneurons produce a rapid burst of two to eight action potentials preceding each contraction of the subumbrella. Spontaneous bursting persists in high‐Mg++ seawater. Injected ramp currents indicated a “bursty” character of the swim motorneurons as suprathreshold depolarizations produced repetitive bursting with an increasing burst frequency with increased depolarization. Hyperpolarizing currents locally blocked spiking in swim motorneurons.Intercellular coupling was demonstrated with Lucifer Yellow injection and dual electrode recordings. In dye fills, only the large neurons of the inner nerve ring were dye‐coupled.Two pieces of evidence suggest that swim motorneurons activate the overlying epithelial cells via chemical synapses. First, direct synaptic connections have been noted in ultrastructural examination of the inner nerve ring region. Second, dual recordings from a swim motorneuron and an epithelial cell reveal a 1:1 correspondence between neuron spikes and epithelial synaptic potentials. The synaptic potentials occur with a latency as short as 3 ms which is constant in any one recording session. The results suggest that the swim motorneuron network of Aequorea not only performs a motorneuron function, but also serves as the pattern generator for swimming activity.
Quantification of ultrastructural symmetry at molluscan chemical synapses
Authors: McCarrager Gary , Chase Ronald 
Published: January 2005

AbstractTwo criteria were developed to identify symmetrical synapses in the tentacle ganglion of the snail Achatina fulica. First, the concentration of electron lucent vesicles within 20 nm of one membrane had to be less than three times the concentration at the opposed membrane. Second, paramembranous densities had to be present in both cells, as unanimously judged by three independent observers. Nine synapses (27% of sample) satisfied both criteria. It is suggested that these synapses transmit chemically in two directions.
Neuromuscular relationships in the abdomen of the Californian shore crab Pachygrapsus crassipes
Authors: Stephens Philip J. , Leferovich John M. , Klainer Peter 
Published: January 2005

AbstractThere are two pairs of muscles in each abdominal segment of the crab; one pair of flexors and one pair of extensors. In the early larval stages the muscles have short sarcomeres—a property of fast fibers—and high thin to thick filament ratios—a property of slow fibers. In the adult the abdominal muscles are intermediate and slow, since they have fibers with intermediate and long sarcomeres, high thin to thick filament ratios, low myofibrillar ATPase activity, and high NADH diaphorase activity. The different fiber types are regionally distributed within the flexor muscle.Microelectrode recordings from single flexor muscle fibers in the adult showed that most fibers are supplied by three excitatory motor axons, although some are supplied by as many as five efferents. One axon supplies all of the flexor muscle fibers in its own hemisegment, and the evoked junctional potentials exhibit depression. This feature together with the innervation patterns of the fibers are similar to those reported for the deep flexor muscles of crayfish and lobsters. Therefore, in the adult crab, the abdominal flexor muscles have some features in common with the slow superficial flexors of crayfish and other features in common with the fast deep flexor muscles.
Central connections of Limulus ventral photoreceptors revealed by intracellular staining
Authors: Batra Ranjan , Chamberlain Steven C. 
Published: January 2005

AbstractWe stained the central terminations of Limulus ventral photoreceptors by intracellular injection of cobalt chloride into the cell bodies. Axons of these photreceptors enter the protocerebrum via the ventral optic nerve and pass to the medulla. As they reach the surface of the medullar neuropil they branch profusely in fine processes with intermittent varicosities. Each axonal arborization covers about 0.01–0.02 mm2 of this surface immediately adjacent to the medullar ganglion cell layer. Each point on the surface of the medullar neuropil receives, on the average, input from about 6 ventral photoreceptor axons.
Adenosine in cerebral homeostatic role: Appraisal through actions of homocysteine, colchicine, and dipyridamole
Authors: McIlwain Henry , Poll Janet D. 
Published: January 2005

AbstractMammalian neocortical tissues were incubated in [14C] adenine‐containing fluids and their newly‐synthesized adenine derivatives examined after periods of superfusion. Increased [K+] released adenine derivatives from the tissues, a release diminished by homocysteine. Homocysteine acted also to diminish the tissue content of adenosine plus its metabolites hypoxanthine and inosine, while increasing that of S‐adenosylhomocysteine. Hypoxia also increased the tissue content and the output of adenosine plus its metabolites, and again homocysteine augmented the S‐adenosylhomocysteine. Glutamic acid also increased tissue content and output of adenosine and derivatives, an action diminished by homocysteine and associated with augmented S‐adenosylhomocysteine. Colchicine or dipyridamole did not prevent augmentation of S‐adenosylhomocysteine by the reagents described; the sequence from adenosine phosphates to S‐adenosylhomocysteine is concluded to be intracellular and not to involve extracellular formation of precursor adenosine. Adenosine displayed properties consistent with its being involved in two distinct categories of homeostasis, and also with its exerting an inhibitory tone in normal cerebral systems.
Morphology and physiology of a hair plate sensory organ located on the antenna of the rock lobster Palinurus vulgaris
Authors: Vedel J. P. 
Published: January 2005

AbstractAt the level of the J1 joint of each antenna of the rock lobster Palinurus vulgaris a hair plate sensory organ (hp) similar to those described in insects has been observed. The hp is located on the internal side of the S2 segment of the antenna, close to the soft articulating membrane of the J1 joint. It is formed by a triangular surface of cuticle about 3mm2 in area, covered with numerous hairs of different lengths (Figs. 1 and 2). Details of the hp were studied by scanning electron microscopy (Fig. 2). Physiological stimulation of the hp hairs occurs during medial movement of the J1 joint. Under this condition the soft articulating membrane rolls over the hairs and bends them progressively back onto the cuticle. Flexion of all the hairs corresponds to a medial movement of the J1 through 40°. During this type of movement, the number of successively flexed hairs increases linearly (Fig. 3). Electrophysiological recordings of the hp sensory nerve correlated with selective mechanical stimulation of individual hairs demonstrated that each hair is innervated by a single sensory fiber. This sensory neurone responds phasically when the hair is flexed back onto the cuticle (as during an S2 medial movement) and when it returns to its resting position (as during an S2 lateral movement). Most of the sensory neurones are sensitive to the movement velocity of the hairs (Figs. 4 and 5). When the hair is maintained flexed its sensory neurone discharges tonically (Fig. 4). Electrical stimulation of the hp sensory nerve induced reflex actions in the external and internal rotator muscles of the segment S1. These effects were found to selectively activate the tonic motor command of these muscles (Fig. 6).
Tubulin synthesis in the regenerating rat superior cervical ganglion: A biphasic response
Authors: Quesada Marilee H. , Millar David B. , Smejkal Ruthann 
Published: January 2005

AbstractAxotomy of a major cranial post ganglionic branch of the superior cervical ganglion of an adult rat resulted in increased radiolabeling of tubulin and microtubule‐associated proteins after an in vitro 5‐h incubation with [14C]‐methionine. The increased incorporation of the radiolabel began at day 1 postoperatively and exhibited a biphasic response, peaking at days 3 and 8.