bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diurnal rhythms in cyclic nucleotide metabolism in Helix nervous system
Authors: Levitan Irwin B. , Treistman Steven N. 
Published: January 2005

AbstractConcentrations of cAMP (cyclic adenosine 3′,5′‐monophosphate) and cGMP (cyclic guanosine 3′,5′‐monophosphate), in ganglia from the garden snail Helix pomatia, vary considerably over the course of the day. There is a maximum in the concentration of both cyclic nucleotides between 08:00 and 12:00 (lights on 06:00 to 18:00), with the cAMP maximum occurring slightly later than that in cGMP. In addition there can be several smaller maxima in cAMP and cGMP levels; the timing of these can be markedly different from experiment to experiment, with cAMP and cGMP sometimes in and sometimes out of phase with each other. This pattern is observed in Helix which had been activated from the dormant state 4–6 days earlier, but is not present in dormant or in long‐active animals. The cyclic nucleotide rhythm can be seen in ganglia maintained in organ culture, and persists for at least 24 hours after removal of the tissue from the animal. There appears to be little change in the level of basal or Na Fstimulated adenylate cyclase activity in Helix ganglia over the course of the day. On the other hand, both cAMP and cGMP phosphodiesterase activities exhibit rhythms which are consistent with the rhythms in cAMP and cGMP concentrations.
Adult mouse dorsal root ganglia neurons in cell culture
Authors: Scott Brian S. 
Published: January 2005

AbstractA method has been developed for the long‐term culture of dissociated adult mouse dorsal root ganglia (DRG). Of critical importance to the success of this technique was a three‐hour incubation in collagenase which softened the DRG and permitted gentle dissociation. The morphological and electrophysiological features of the dissociated adult DRG were similar to those observed in previous studies of immature (i.e., embryonic and newborn) DRG in culture and also to those of adult DRG in situ.With regard to electrophysiological work, the adult DRG neurons are superior to embryonic and newborn neurons because of their larger size and greatly increased survival in culture (no degeneration for first six days, and thereafter a relatively slow decrease). The adult neurons regenerated nerve fibers to an extent comparable to that of immature neurons. Therefore, the adult DRG cultures might be useful to study factors influencing regeneration in the adult mammalian nervous system. The adult cultures might also be useful to investigate factors influencing the aging process.
The dorsal, unpaired, median neurons of the locust metathoracic ganglion
Authors: Hoyle Graham 
Published: January 2005

AbstractNeurons having large cell bodies in the anterior dorsal median cluster in the metathoracic ganglion of the locust Schistocerca gregaria and the grasshopper Romalea microptera were studied by direct dye injection and reverse filling combined with electrical stimulation and recording. Eight, possibly nine, are of the unpaired type, with a T branch leading into left and right axons that leave the ganglion to terminate in muscles. Another six are probably paired, and may be interneurons. Five of the 8 or 9 unpaired neurons have one axonal branch in both N4 and N5, on both sides: the others have but a single branch. One of the nine, DUMETi, has left and right axons exclusively innervating the jumping muscles, and another, DUMDL, has left and right axons exclusively innervating the dorsal longitudinal flight muscles. Neither the locations, sizes or numbers of somata, nor their locations were as constant as is the case for ordinary ventral motorneurons.
Membrane‐potential‐sensitive dyes for optical monitoring of activity in Aplysia neurons
Authors: Woolum John C. , Strumwasser Felix 
Published: January 2005

AbstractTwo membrane‐associated dyes (WW375 and NK2367) which change their absorption of light when the membrane potential changes have been studied using several preparations from Aplysia. Action potentials are easily observed in nerve trunks (from a number of axons), in bag cell clusters, in some of the larger single cells of the parietovisceral ganglion, and in the optic nerve. Physiological effects of the dyes on the circadian rhythm of activity in the eye are described.
A biochemical comparison of Xenopus laevis and mammalian myelin from the central and peripheral nervous systems
Authors: Quarles R. H. , Sakuragawa N. , Everly J. L. , Pasnak C. F. , Webster H. deF. , Trapp B. D. 
Published: January 2005

AbstractMyelin purified from the central nervous system of Xenopus laevis contained the same major lipid and protein components as human myelin. However, some minor differences in the myelin proteins were noted. The Xenopus basic protein had a higher apparent mol wt. on sodium dodecyl sulfate gels than the corresponding mammalian protein. The absolute specific activity of 2′,3′‐cyclic nucleotide 3′‐phosphohydrolase in the Xenopus myelin was considerably higher than in mammals. There were differences in the high mol wt. proteins, and the glycoproteins in Xenopus myelin were more heterogeneous than those in mammals. Peripheral myelin from Xenopus sciatic nerve was compared with that from the rat. The lipids in the two types of myelin were similar. There was a major glycoprotein in the Xenopus myelin corresponding to the P0 protein and a basic protein of slightly larger mol wt. than the P1 protein of rat myelin.
Calcium‐dependent increase in spike duration during repetitive firing of Aplysia axon in the presence of TEA
Authors: Horn Richard , Miller Jeffrey J. 
Published: January 2005

AbstractRepetitive stimulation was studied in the axon of the giant neuron, R2, of Aplysia in the presence of TEA. In 25 or 50 mM extracellular TEA, a plateau develops on the axon spike during repetitive stimulation at frequencies greater than 3/sec. The plateau in extracellular TEA is inhibited by 30 mM CoCl2 or 1 mM CdCl2, and is enhanced by raising the Ca concentration. Intracellular TEA induces a plateau on the axon spike at frequencies less than 1/30sec. This plateau increases in duration with repetitive stimulation at higher frequencies and is inhibited by 30 mM CoCl2 or 1 mM CdCl2. The increase in spike duration during repetitive firing in the presence of TEA is indicative of an increased entry of Ca during the spike train.
Hyperpolarizing potentials induced by Ca‐mediated K‐conductance increase in hamster submandibular ganglion cells
Authors: Suzuki Takashi , Kusano Kiyoshi 
Published: January 2005

AbstractThe mechanisms of three types of hyperpolarizing electrogenesis in hamster submandibular ganglion cells were analyzed with intracellular microelectrodes. These included (1) spike‐induced hyperpolarizing afterpotential (S‐HAP), (2) spontaneous transient hyperpolarizing potential (HP), and (3) the hyperpolarizing (H) phase of postsynaptic potential (PSP). Most of these hyperpolarizing potentials were due to conductance increases and reversed polarity at membrane potential (Em) between −70 and −85 mV, which was close to the K‐equilibrium potential. The average resting potential of ganglion cells was −53 mV. Action potential overshoot increased slightly in high [Ca2+]0 and decreased in low [Ca2+]0. In most neurons action potentials were completely suppressed by 10−7 M tetrodotoxin (TTX). The S‐HAP has an initial component due to delayed rectification and a late component. The late component is enhanced by increasing [Ca2+]0, or by applying Ca‐ionophore (A23187), TEA, caffeine, or dibutyryl cyclic (DBc‐) AMP; it is suppressed by decreasing [Ca2+]0, or by applying Mn2+. Perfusion with Cl−‐free saline reduced membrane potential slightly but did not modify the S‐HAP. Depolarizing pulses also induced hyperpolarizing afterpotential (D‐HAP), similar to the S‐HAP. Spontaneous transient HPs occurred in some neurons at irregular intervals. HPs were insensitive to TTX but were suppressed by Mn2+. Caffeine induced low frequency rhythmic HPs in many neurons, often alternating with periods of repetitive spiking. The PSP was a monophasic depolarizing (D‐) potential in some neurons, but in others the D‐phase was followed by a small H‐phase. Perfusion with A23187, caffeine or DBc‐AMP increased the H‐phase of the PSP. Perfusion with K+‐free saline or treatment with 10−5M ouabain did not abolish the H‐phase of PSPs. These membrane potential‐dependent phenomena appear to be induced mainly by Ca‐mediated K‐conductance increases. This mechanism contributes to the regulation of low‐frequency repetitive firing in submandibular ganglion cells.
Autophosphorylation of chick brain synaptic polypeptides. Phosphorylation of proteins during incubation of intact synaptosomes with 32PO4
Authors: Breithaupt Thomas B. , Babitch Joseph A. 
Published: January 2005

AbstractChick brain synaptosomes incorporated phosphate into proteins when incubated in physiological buffer containing energy sources. Sodium dodecyl sulfate polyacrylamide gel electrophoresis indicated that three synaptosomal polypeptides were significantly phosphorylated after 15 sec incubation while at least fifteen polypeptides were active kinase substrates after 15 min incubation. Labeled synaptosomes were hypotonically lysed and separated by centrifugation into soluble, membrane, and mitochondrial fractions. Every fraction exhibited significant phosphate incorporation. Electrophoresis revealed that each fraction had several unique phosphorylated polypeptides and a distinctive phosphorylation pattern. The same polypeptides appear to be labeled whether MgATP was added to synaptic plasma membranes or synaptic plasma membranes were isolated after synaptosomal autophosphorylation.
An endogenous motor program for sand crab uropods
Authors: Paul Dorothy Hayman 
Published: January 2005

AbstractA stereotyped pattern of spontaneous, rhythmic bursting in motoneurons of three prinicipal uropod muscles in the sand crab Emerita analoga has been recorded from a deafferented chain of the foru most‐posterior abdominal ganglia. This endogenous motor program resembles the electromyogram pattern recorded from return‐stroke and power‐stroke muscles in swimming crabs in that (1) latencies of power‐stroke bursts and burst periods are positively correlated with each other and (2) durations of power‐stroke bursts are brief and mearly invarient. The endogenous program differs from the electromyogram pattern in having longer periods and return‐stroke bursts which are brief and sporadic. The neural oscillator underlying the endogenous motor program, therefore, appears to drive the power stroke. Circumstantial evidence suggests that it may also inhibit return‐stroke motoneurons concurrently with excitation of the power‐stroke excitor.
Primitive nervous systems: Action of aminergic drugs and blocking agents on activity in the ventral nerve cord of the flatworm Notoplana acticola
Authors: Keenan Larry , Koopowitz Harold , Bernardo Kerry 
Published: January 2005

AbstractElectrically evoked activity in the submuscular ventral longitudinal nerve cords of Notoplana acticola is depressed by GABA and glycine in the presence of high magnesium concentrations. This inhibition occurs with 0.001–0.01 millimolar concentrations of these putative aminergic neurotransmitters and is reversible when washed out. The action of GABA and glycine was reversed nonspecifically by picrotoxin, bucuculline, and strychnine. PTZ (Pentylenetetrazole) was shown to mimic the effects that these blocking agents had on evoked activity when they were tested alone. The release of inhibition by these blocking agents is similar to that of decerebration. Three possible mechanisms responsible for synaptic activity in high Mg2+ concentrations are discussed and the possibility that the effector site of interaction may be the chloride ionophore is explored.
Plasticity of feeding behavior in the opisthobranch mollusc Navanax
Authors: Susswein A. J. , Bennett M. V. L. 
Published: January 2005

AbstractSeveral forms of plasticity of feeding behavior were investigated in Navanax. Navanax is a gastropod mollusc which lacks a radula, and ingests prey with suction caused by rapid pharyngeal expansion. Feeding is little affected by handling or posture and is resistant to the noxious stimulus of cutting through the body wall. Feeding is affected by arousal, as shown by a decrease in latency following initial exposure to food. The feeding response also habituates, as shown by an increase in latency when feeding responses are elicited without allowing animals to engulf food. The latency increase is not likely to be due to motor fatigue, since it can be partially reversed by dishabituation with an alternate prey species. Continued feeding causes satiation, as shown by increased feeding latencies and eventual cessation of feeding after a mean weight gain of 42.0% of initial animal weight (N = 12). Another form of plasticity occurs when Navanax are presented with food too large to swallow whole. Navanax either cease to respond after a few presentations, perhaps due to habituation, or maintain suction on the partially swallowed prey for an extended period of time. During extended sucks, the more deeply ingested portions are digested.
Fine structure of an octopaminergic neuron and its terminals
Authors: Hoyle G. , Colquhoun W. , Williams M. 
Published: January 2005

AbstractThe large octopaminergic dorsal unpaired median neuron of the locust that innervates the extensor tibiae muscle, DUMETi, was examined electronmicroscopically. Its soma contains many Golgi complexes apparently making dense‐core vesicles similar to those found in peripheral branches and terminals. There are also larger stores of the dense material in the soma, especially near the exit of the principal neurite, that are not in vesicular form. Since the neurons can readily be penetrated and stimulated by microelectrodes, they form favorable subjects for direct studies of the control of neurosecretion. Preterminal fine branches of the neuron were located in proximal outer bundles of muscle fibers into which they had been traced electrophysiologically. They contain numerous large dense‐core vesicles arrayed in rows near microtubules. These fine branches have a thick layer of collagenous connective tissue between the axon and the muscle fiber. Final terminals have varicosities containing many vesicles, lying inside the outer layers of the sarcolemmal complex of muscle fibers. They do not form synaptic structures. Terminals of another DUM neuron, one that innervates the dorsal longitudinal flight muscles (DUMDL), were similar in detail to those of DUMETi. DUMETi swelled about 20‐fold in cross‐sectional area above a ligature, in a 12‐hr period, indicating that there is an extensive centrifugal flow of material in it, and sprouted a branch.
Axonal transport in rats rendered paraplegic following a single subarachnoid injection of either batrachotoxin or 6‐aminonicotinamide into the spinal cord
Authors: Boegman R. J. Boegman , Albuquerque E. X. 
Published: January 2005

AbstractBatrachotoxin (BTX) or 6‐aminonicotinamide (6‐AN) when injected into the subarachnoidal space of the lumbar spinal cord block fast axonal transport of 3H‐protein in motor nerves. Axonal transport recovers partially within one day after administering BTX while the effect of 6‐AN lasts for more than 21 days. These observations are discussed in relation to the onset and recovery of membrane depolarization observed in the extensor muscle.
Drosophila clock mutations affect the morphology of a brain neurosecretory cell group
Authors: Konopka Ronald J. , Wells Steven 
Published: January 2005

AbstractMutations that eliminate circadian rhythmicity in two species of Drosophila affect the location of cells in a neurosecretory cell group. This is the first example of mutations which affect the morphology of an identifiable cell group in the Drosophila brain.
Control of gill reflex habituation and the rate of EPSP decrement of L7 by a common source in the CNS of Aplysia
Authors: Lukowiak Ken , Peretz Bertram 
Published: January 2005

AbstractIt was found in older Aplysia that the rate of decrement of the EPSP evoked in L7 by repeated tactile stimulation of the gill was dependent on the strength of the applied stimulus and that the rate of decrement paralleled the rate of gill reflex habituation. As the stimulus intensity was increased both rates slowed. In contrast, it was found in young Aplysia that the rate of EPSP decrement and the rate of gill reflex habituation were independent of the strength of the stimulus applied to the gill. Neither rate changed as the stimulus intensity was changed. Moreover, L7's of young animals are more responsive to tactile stimuli applied to the gill than are L7's of older animals and the difference in excitability is not due to any differences in passive membrane properties between the L7's in young and older Aplysia. These findings are fully consistent with and supportive of the proposal that a common neuronal source in the parieto‐visceral ganglion of Aplysia controls the rate of gill reflex habituation, the synaptic input to L7, and the rate of decrement of this input, evoked by repeated tactile stimulation of the gill. Additinally, it was proposed that this common source is developed in completely in the young. As a consequence of this incomplete development, young Aplysia exhibit less adaptability to changing stimulus conditions and, in general, less ability to suppress their behavior. It may thus be possible to study directly developmental changes in the nervous system which act to transform juvenile behavior to adult behavior.
Changes in the composition of labeled protein transported in motor axons during their regeneration
Authors: Bisby M. A. 
Published: January 2005

AbstractLabeled proteins transported in rat sciatic nerve axons after application of L‐(35S) methionine to motoneuron cell bodies were characterized by SDS‐polyacrylamide gel electrophoresis. During nerve regeneration following a crush injury, changes were observed in the composition of the fast‐transported proteins. The major change was an increase in relative amount of a 18,000‐dalton polypeptide (S2). Less dramatic changes occurred in a 66,000‐dalton polypeptide (N) which also increased, and in a 13,000‐dalton polypeptide (T) which decreased. The increase in S2 and N was significant by three days after injury and all changes were maximal between 7 and 14 days. A return to normal proportions was reached between 21 and 42 days. It is concluded that axonal injury produces, among its other effects, an alteration in the proportions of proteins transported into the axon. It remains to be determined whether these changes are prerequisites for axonal regeneration, or facilitate regeneration, or are incidental to it.
Interommatidial sensilla of the praying mantis: Their central neural projections and role in head‐cleaning behavior
Authors: Zack Sheldon , Bacon Jon 
Published: January 2005

AbstractThe compound eye of the praying mantis is covered with approximately 600 bristles and campaniform sensilla. Their afferents project to the brain, and to the suboesophageal and prothoracic ganglia. Cutting the eye branch of the dorsal tegumentary nerve (DTN), the peripheral nerve innervating the corneal sensilla, makes it impossible to initiate head grooming by tactile stimulation of the eye. This stimulus is a strong releaser of grooming behavior in normal animals. Head grooming can be initiated, after cutting the eye branch of the DTN, by stimulation of the frons (the operation leaves the sensory innervation of this part of the cuticle intact). Frame‐by‐frame analysis of films of head grooming after cutting the nerve reveals a reduction of the speed at which the forelimb is brushed across the surface of the head and eye. The significance of this finding is discussed in terms of a putative feedback loop from the corneal sensilla to the motor neurons controlling the grooming movements.
Action of colchicine on membrane currents and synaptic transmission in Aplysia ganglion cells
Authors: Baux G. , Simonneau M. , Tauc L. 
Published: January 2005

AbstractThe action of colchicine, a drug known to disrupt microtubules, on synaptic transmission and voltage‐dependent phenomena was studied. Colchicine depressed transmission in both cholinergic and noncholinergic Aplysia ganglionic synapses. In some synapses, this effect was partly due to the curare like properties of the alkaloid. Ca2+ currents, analyzed by voltage clamp techniques, were rapidly depressed by intracellular injection of colchicine and more slowly depressed by external application. Injected colchicine acted at much lower concentrations than required extracellularly. The implication of the reduced calcium influx in synaptic transmission is discussed. Colchicine caused a shift in the reversal potential of acetylcholine‐activated chloride channels in a direction consistent with an increased intracellular chloride activity. It was concluded that the wide range of actions of colchicine on membrane properties should be taken into account when this drug is used in biological research.
Vertical motion detectors and their synaptic relations in the third optic lobe of the fly
Authors: Bishop Cynthia A. , Bishop Lewis G. 
Published: January 2005

AbstractThe synaptic relations of the giant vertical cells in the lobula plate of the fly were investigated using electron microscopical procedures and Lucifer yellow dye backfill and injection techniques. Histological features of the giant vertical cells are described. The giant vertical cells are exclusively postsynaptic in the lobula plate. They function to integrate input from dense arrays of chemical synapses and have a wide spatial input from the lobula plate. The giant vertical cells are postsynaptic to perpendicularly occurring cells. There are two classes of cells presynaptic to the vertical cells, one of which contains large dense‐core vesicles. The giant vertical cells are not the only cells postsynaptic to these two classes of perpendicualr cells. A second group of smaller tangential cells, the twin vertical cells, were also found postsynaptic to many of the same cells that synapsed with the giant vertical cells. The twin vertical cells and the giant vertical cells are therefore integrating some of the same information in the lobula plate.
Cyclic AMP, 5‐HT, and the modulation of transmitter release at the crayfish neuromuscular junction
Authors: Enyeart John 
Published: January 2005

AbstractIn this study it was found that several agents which elevate cAMP levels in cells also increase dramatically the quantity of transmitter released from crayfish excitatory nerve terminals in response to a stimulus. With respect to time course and magnitude, the increase produced by one of these agents, the cyclic nucleotide phosphodiesterase inhibitor Squibb 20,009 (SQ 20,009), is unlike any reported for such a drug at a synapse. Additionally, SQ 20,009 potentiated the facilitation of transmitter release produced by serotonin (5‐HT) at this synapse. These results establish a possible role for cAMP in the control and modulation of transmitter release at the crayfish neuromuscular junction (NMJ). They further suggest that 5‐HT functions here by activation of a presynaptically located adenylate cyclase.