bluuebunny/crossref_metadata_2025_split huggingface dataset:
Correlated effects of acetylcholine and cyclic guanosine monophosphate on membrane properties of mammalian neocortical neurons
Authors: Swartz B. E. , Woody C. D. 
Published: January 2005

AbstractThe effects of successive extracellular iontophoresis of acetylcholine (ACh) and atropine, and intracellular hyperpolarizing iontophoresis of cyclic GMP (cGMP) were studied in single neurons of the coronal‐pericruciate cortex of awake cats. (a) Fifty‐seven percent of the neurons that were tested responded to ACh with an increase in neuronal input resistance (Rm) and 50% responded to ACh with an increase in firing rate; 65% responded to cGMP with an increase in Rm and 60% responded to cGMP with an increase in firing rate. (b) After application of atropine, increases in Rm and firing rate associated with iontophoresis of ACh failed to recur. (c) Persistent increases in Rm following application of ACh accompanied by current‐induced neuronal discharge were not diminished by subsequent application of atropine. (d) Atropine did not prevent increases in Rm and firing rate associated with intracellular iontophoresis of cGMP. (e) All cells tested with both ACh and cGMP that were shown initially to respond to extracellular ACh with increases in Rm were later shown to have comparable responses to cGMP.
Interganglionic axonal transport of neural peptides within the nervous system of Aplysia
Authors: Berry Robert W. , Geinisman Yuri 
Published: January 2005

AbstractNeurons of the circumesophageal ganglia of Aplysia synthesize 1‐2000 dalton peptides and subject them to axonal transport in large quantities in the pleuro‐visceral connective and pedal nerves. Most of the protein transported in the connective nerves accumulates in the abdominal ganglion, although some passes out its peripheral nerves. Autoradiography revealed no evidence for terminations of the transporting axons in possible neurohemal areas of this ganglion. It is suggested that these data reflect the existence of a pathway mediating the “directed delivery” of neural peptides in this nervous system.
Secretion of axonally transported neural peptides from the nervous system of Aplysia
Authors: Berry Robert W. 
Published: January 2005

AbstractThe possibility that proteins reaching the abdominal ganglion of Aplysia by axonal transport from the circumesophageal ganglia might be subject to secretion in that structure was examined. Transported labeled protein was found to be released from the abdominal ganglion; such release was enhanced by exposure to a high K+ medium and by electrical stimulation of the transporting axons. Stimulation of release was inhibited by lowering the Ca2+/Mg2+ ratio of the medium. The released material is predominantly of 1–2000 daltons in molecular weight and appears to have been derived from a group of transported peptides of about the same size. The possibility is raised that these data may reflect the existence of a peptidergic second‐order neurosecretory pathway in this nervous system.
Batrachotoxin inhibits axonal transport without affecting membrane potential in single neurons of Aplysia californica
Authors: Kumara‐Siri M. H. 
Published: January 2005

AbstractIntrasomatic injection of 0.25 ng of batrachotoxin (BTX) caused no depolarization of giant cerebral neurons (GCN) of Aplysia californica within 4 hr at 23° C. The amplitude of action potential and the input resistance were slightly and reversibly decreased. The same dose of BTX caused a 68% inhibition of fast axonal transport.
Mg++‐sensitivity of neuromuscular transmission in two crustaceans: Correlation with blood Mg++ levels
Authors: Lang Fred , Cleveland Mark B. , Atwood Harold L. 
Published: January 2005

AbstractNeuromuscular transmission was measured in muscles of spider crabs (Hyasareneus) and lobsters (Homarus americanus). Solutions containing 40 and 10 mM/1 Mg++, which were approximately the same as those measured in the blood of Hyas and Homarus, respectively, were used to soak the preparations prior to testing. In Homarus, neuromuscular transmission was severely depressed by 40 mM Mg++. In spider crabs, neuromuscular transmission was not severely depressed. Although the amount of transmitter released by nerve impulses was reduced, total membrane depolarization during trains of impulses was not reduced because a compensating increase in muscle fiber membrane resistance occurred in Hyas preparations exposed to 40 mM Mg++. Hyas, but not Homarus, is physiologically adapted to function at relatively high blood Mg++ concentrations.
Properties of a calcium‐activated protease in squid axoplasm which selectively degrades neurofilament proteins
Authors: Pant Harish C. , Gainer Harold 
Published: January 2005

AbstractAxoplasm extruded from the giant axon of the squid contains Ca2+‐activated proteases. The protease in the 100,000X g of supernatant of axoplasm is very specific and degrades only the 200,000 MW, neurofilament protein (NF200), whereas the protease(s) in the pellet has a much wider range of substrate specificity. The activation of the supernatant protease is restricted to the Ca2+ ion, and no other divalent cation will substitute. The protease requires Ca2+ at a higher concentration than 0.5 mM for activation, and has a pH optimum of about 7.5. Degradation of the NF200 appears to proceed through a 100,000 MW and possibly a 47,000–50,000‐MW intermediate form before degradation to TCA‐soluble peptides. Activity of the protease is inhibited by divalent cation chelators, Cu2+ and Fe2+, sulphydryl inhibitors, and leupeptin. This specific Ca2+‐activated protease in squid axoplasm has identical properties to Ca2+‐activated proteases found in various non‐neural tissues. Despite its narrow protein substrate specificity, Ca2+‐activated protease purified from human platelets effectively degrades squid NF200, suggesting a possible structural relationship between platelet and muscle actin‐binding proteins and neurofilament proteins.
Innervation, synaptic physiology, and ultrastructure of three muscles of the second maxilla in crayfish
Authors: Moody‐Corbett F. , Pasztor V. M. 
Published: January 2005

AbstractInnervation patterns, synaptic properties, and fiber ultrastructure were studied in three muscles of the second maxilla of Procambarus clarkii and Orconectes virilus. All three muscles, ASDM (anterior scaphognathite depressor muscle), CFM (coxopodite flexor muscle), and SFM (scaphognathite flexor muscle), were polyneuronally innervated, receiving two, three, and four excitors, respectively. Two of the four excitors innervating SFM were branches of the two excitors supplying ASDM. No muscle received inhibitor axons. Synapses tended to be low output and show a high degree of facilitation as measured by the facilitation index of Atwood and Bittner. Ranges of EPSP amplitudes and facilitation indices were common to all excitors. Muscle fibers uniformly showed short sarcomere lengths and low thin‐to‐thick filament ratios. These physiological and ultrastructural peripheral features are consistent with the nature of the motor score from the central rhythm generator.
Fine structural analysis of membrane changes during reaggregation culture of chick optic tectum
Authors: Wood John G. , McLaughlin Barbara J. , Byrd Frances I. 
Published: January 2005

AbstractThin section and freeze‐fracture electron microscopy have been used to characterize the changes in membrane morphology of reaggregating cultures of chick optic tectum. The cells are rounded and freely dispersed at 0 hr after dissociation. Between 2 and 6 hr the cells become closely apposed on all sides by other cells and form small aggregates. At this time punta adhaerentia junctions and focal densities are seen along the membranes of neighboring cells. Between 1 and 5 days in vitro (DIV) neurites containing growth cone regions are present. At 5 DIV the first synaptic contacts are observed. Between 7 and 14 DIV, the number of synaptic contacts increase and fewer growth cone regions are observed. As early as 7 DIV profiles are observed which strongly resemble both astrocytic and oligodendroglial cell somata and processes. Freeze‐fracture analysis of aggregates at 0–4 hr reveals a sparse particle distribution on the P and E faces of apposed cells. By 1 DIV small clusters of loosely packed, large sized particles are seen on the P face of apposed cell membranes which may represent junctional contacts. Apparent coated vesicle fusion sites are common on the P face at 1–2 DIV. By 7 DIV, E face particle arrays are seen on cell bodies and neurites which correspond to specializations characteristic of excitatory synaptic junctions. By 8–10 DIV particle arrays are seen on the P face of post‐synaptic membrane which may represent inhibitory synaptic contacts. Other types of particle specializations seen in freeze‐fracture replicas include: specializations characteristic of gap junctions between cells and orthogonal assemblies of particles thought to be characteristic of astrocytes.
A method for controlling body wall turgor during electrophysiological recording from central neurons in ecdysing insects
Authors: Carlson Joseph R. 
Published: January 2005

AbstractA method for obtaining intracellular recordings from central neurons of insects during the performance of ecdysial behaviors is described. Body wall turgor must be restored to high levels in order to provide the CNS with appropriate sensory feedback required for the generation of motor output. This is accomplished by installing the insect in a decompression chamber so that an opening in the animal's ventral surface communicates with the atmosphere. Reduction of chamber pressure causes expansion of the insect's body, and access to thoracic ganglia is provided by the ventral opening in the animal's body wall. It is suggested that adaptations of this technique to invertebrates with hydrostatic skeletons is possible and would permit electrophysiological studies of behaviors which normally require high blood pressures for their performance.
Synthesis of the myelin proteolipid protein in the developing mouse brain
Authors: Campagnoni Anthony T. , Hunkeler Markus J. 
Published: January 2005

AbstractMice ranging in age from 16 to 44 days were injected intracerebrally with 3H‐leucine, and incorporation into total brain proteolipids and the myelin proteolipid protein was measured. All proteolipids were isolated from whole brain by ether precipitation and separated into their individual components by SDS polyacrylamide gel electrophoresis. Two major proteolipids with apparent molecular weights of 20,700 and 25,400 were observed in these preparations, and their proportion increased over the developmental period examined. A Ferguson plot analysis comparing these proteins with those of isolated myelin showed that the 25,400‐dalton proteolipid component from whole brain was the myelin proteolipid protein. Rates of incorporation of 3H‐leucine into total brain proteolipids peaked at 22 days of age. Synthesis of the myelin proteolipid protein increased rapidly to a maximum value at 22 days and decreased rather slowly until at 44 days it was about 83% of its maximum rate of synthesis. The data indicate that the developmental pattern of synthesis of the myelin proteolipid protein is unlike that of the myelin basic proteins. Synthesis of the major myelin proteins is developmentally asynchronous in that peak synthesis of the myelin proteolipid appears to occur several days later than the basic proteins. In addition, it maintains its maximum rate of synthesis over a longer period of time than do the basic proteins.
Pineal cells enhance choline acetyltransferase activity in sympathetic neurons
Authors: Rowe Vernon , Parr James 
Published: January 2005

AbstractCells derived from the neonatal rat pineal gland were cocultured with cells derived from neonatal rat superior cervical ganglia (SCG) in an attempt to determine whether a sympathetic target organ with only adrenergic properties could enhance the development of adrenergic transmitter properties in sympathetic neurons in tissue culture. Choline acetyltransferase was measured as an index of cholinergic differentiation, and tyrosine hydroxylase was measured as an index of adrenergic differentiation. As indices of total cell number and cellular volume, DNA and protein, respectively, were also measured. We found that the pineal‐SCG cocultures contained ten times greater choline acetyltransferase activity than sister neuronal cultures cultured without pineal cells, thus indicating that the pineal cells enhanced cholinergic properties in the sympathetic neurons. This cholinergic enhancement was dependent upon the presence of nerve growth factor and could not be obtained with pineal‐conditioned medium. Tyrosine hydroxylase activity, measured on cultures sister to those mentioned above, was low in all cultures and decreased somewhat in SCGs cultured alone. TH activity in the pineal‐SCG cocultures, however, increased slightly. Some tyrosine hydroxylating activity developed in pineals cultured alone, however, and may have been responsible for the small increase in tyrosine hydroxylase activity noted in the pineal‐SCG cocultures. The implications of these results for a determination of the role that target organ plays in the development of the transmitter properties of sympathetic neurons are discussed.
Biochemistry and ultrastructure of serotonergic nerve endings in the lobster: Serotonin and octopamine are contained in different nerve endings
Authors: Livingstone Margaret S. , Schaeffer Susan F. , Kravitz Edward A. 
Published: January 2005

AbstractIn this article we report that the distribution of serotonin in the lobster nervous system parallels the distribution of octopamine and that the same tissues that contain endogenous serotonin can synthesize it from tryptophan. Octopamine and serotonin are highly concentrated in a neurosecretory region of the second thoracic roots in association with a group of neurosecretory cells. The roots possess separate high‐affinity uptake systems for both serotonin and tryptophan. Radioactive serotonin, accumulated in tissues during incubations with either tritiated serotonin or tritiated tryptophan, can be released, in a calcium‐dependent manner, by depolarization with potassium. A detailed morphological examination of the second thoracic roots shows four distinct categories of nerve endings in the vicinity of the neurosecretory cells. Octopamine is synthesized in one of these types of endings and serotonin in another. The high‐affinity uptake systems for serotonin and tryptophan are found only in association with the endings that make serotonin. These endings and all the biochemical parameters of serotonin metabolism in the roots are selectively destroyed by previous injection of animals with the neurotoxin 5,7‐dihydroxytryptamine.
Unique, identifiable local nonspiking interneurons in the locust mesothoracic ganglion
Authors: Wilson John A. 
Published: January 2005

AbstractThe hypothesis that local nonspiking interneurons are unique and identifiable has been tested rigorously for a neuron in the mesothoracic ganglion of the locust. Neurons were physiologically characterized and subsequently stained with cobalt ions. The resulting preparations were examined in whole mounts and serial sections. It is concluded that at least three neurons are unique, based upon a combination of their function, gross morphology, and the location and size of their main processes relative to other neurons. It is strongly suggested that there are other local nonspiking interneurons that are unique and identifiable. A classification system for local nonspiking interneurons is proposed. The implications of this finding for future neuroethological studies are discussed.
Studies on the localization of newly added membrane in growing neurites
Authors: Feldman E. L. , Axelrod D. , Schwartz M. , Heacock A. M. , Agranoff B. W. 
Published: January 2005

AbstractExplant culture of the adult goldfish retina results in vigorous neuritic growth, provided that the optic nerve has been previously crushed in vivo. The site of new membrane addition in these growing neurites was studied with a membrane‐binding lectin Concanavalin A (Con A) in conjunction with a fluorescent indirect antibody method. Explant cultures were labeled with Con A, followed by rabbit antibodies to Con A. This treatment was shown to immobilize Con A receptors while permitting growth. Twenty‐four hours later, the washed preparation was treated with fluorescent goat antirabbit antibodies. The bound fluorescent antibodies appeared as a pattern of contiguous fluorescent speckles confined to the area of old growth while regions near the distal end of the neurite were not fluorescent. These results are compatible with the hypothesis that new membrane is added in the region of the growing tip of the neurite.
Extent of multiple innervation of purkinje cells by climbing fibers in the olivocerebellar system of weaver, reeler, and staggerer mutant mice
Authors: Mariani Jean 
Published: January 2005

AbstractMultiple innervation of cerebellar Purkinje cells (PCs) by climbing fibers (CFs) has been described recently in adult weaver, reeler, and staggerer mutant mice, instead of the monoinnervation found in normal adults. In the present study, the extent of this multiple innervation was estimated by two methods, using both evoked and spontaneous activity of the olivocerebellar system. Concordant values were obtained: the mean number of CF collaterals per PC was between 3.5 and 4 in weaver and staggerer and close to 3.2 for the multiply innervated PCs of reeler mice. These values are of the same order of magnitude as those for the transient multiple innervation in developing rats (Mariani and Changeux, 1981a, b).
Evidence for peptide‐mediated neurotransmission in a molluskan brain
Authors: Snow Robert W. 
Published: January 2005

AbstractThe previous report (Snow, 1982) characterized the monosynaptic actions of an identified cerebral interneuron (C2) in the marine mollusk Tritonia. The C2 neurons produce four types of postsynaptic potentials in an identified pedal neuron (Pd5). A high‐molecular‐weight (≈︁1400 daltons by Sephadex G‐15 gel filtration) compound, which could mimic the four postsynaptic responses in Pd5, was isolated from C2 somata. The C2 somata had the ultrastructural characteristics of peptide‐secreting cells, including profuse rough endoplasmic reticulum and large (170 nm average diameter) dense secretory vesicles. These data are consistent with the hypothesis that the synaptic transmitter of C2 neurons is a peptide(s).
Attenuation of catecholamine‐coupled adenylate cyclase following surgical isolation of rat caudate
Authors: Pajer Kathleen A. , Palmer Gene C. , Chronister Robert B. , Marco Luis A. 
Published: January 2005

AbstractSix weeks following complete unilateral surgical isolation of the rat caudate nucleus, activation of adenylate cyclase was reduced in response to dopamine (DA), norepinephrine (NE), 5′‐guanylyl‐imidodiphosphate [Gpp(NH)p], DA + Gpp(NH)p, and NaF. The low Km form of cyclic AMP phosphodiesterase was elevated in the isolated side when compared to the intact caudate. No changes in activities of guanylate cyclase or in high Km cyclic AMP phosphodiesterase (with or without the calcium‐dependent regulator protein, calmodulin or CDR) were observed between the control and isolated caudate. Histologically, the neural damage to the isolated caudate was principally confined to reduced numbers of dendritic spines of the remaining intrinsic caudate neurons.
All‐or‐none control of the bursting properties of the pacemaker neurons of the labster pyloric pattern generator
Authors: Moulins Maurice , Cournil Isabelle 
Published: January 2005

AbstractIn Crustacea the central pattern generator for the pyloric motor rhythm (filtration to the midgut) is known to be located within the stomatogastric ganglion (STG); its cycling activity is known to be organized by three endogenous burster neurons acting as pacemakers and driving 11 follower neurons. In Homarus, recordings from the isolated stomatogastric nervous system (Fig. 1) indicate that (1) the pyloric output can be generated only when the STG is afferented (i.e., connected to the more rostral oesophageal and commissural ganglia) (Fig. 2) and (2) the deafferntation of the STG results in a complete loss of the bursting properties of the pacemaker neurons (Fig. 4). Manipulation of the STG inputs responsible for unmasking the properties of the pacemakers strongly suggests that (1) they are not phasic inputs (Fig. 5) and (2) they are long‐term acting inputs (Fig. 6). These results provide evidence for a neural all‐or‐none control of the bursting properties of the pacemaker neurons of a motor pattern generator.
Ultrastructure of the water‐movement‐sensitive sensilla in the medicinal leech
Authors: Phillips Christine E. , Friesen W. Otto 
Published: January 2005

AbstractBehavioral and physiological experiments have shown that medicinal leeches are able to detect low amplitude surface waves, and further, that the transduction of this stimulus modality occurs primarily, if not exclusively, at the annular sensilla (Young, Dedwylder, and Friesen, 1981; Friesen, 1981). Here we examine the morphology of these specialized sensory structures using light, scanning electron, and transmission electron microscopes. We found that three types of ciliated sensory cells occur at the sensilla: (1) a uniciliate cell, with an axial cilium that projects at least 12 μm beyond the cuticle; (2) a multiciliate cell with from two to four grouped cilia that extend 1–3 μm beyond the cuticle; and (3) a second multiciliate cell, whose cilia project parallel to the body surface but remain within the cuticle. The cilia of all three cell types arise from the cuplike depressions which form the apices of slender, elongated cells (approximately 2 μm diameter × 50 μm length). A complexly interconnected ring of microvilli surrounds the cilium of the uniciliate cells. The morphology of the uniciliate cells closely resembles the structure of vibration‐sensitive sensory neurons found in other species. We propose, based on previous results and our new findings, that the uniciliate receptor cells are the sensillar movement receptors which mediate leech sensitivity to water movements.
Malice's wonderland: Research funding and peer review
Authors: Osmond D. H. 
Published: January 2005

AbstractThe players all played at once, without waiting for turns, quarreling all the while and fighting for the hedgehogs; and in a very short time the queen was in a furious passion and went stamping about, and shouting “off with his head” or “off with her head,” about once a minute.Alice began to feel very uneasy: to be sure she had not as yet had any dispute with the queen, but she knew that it might happen any minute, “and then” thought she, “what would become of me? They're dreadfully fond of beheading people here: the great wonder is, that there's any one left alive”.