bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neurotrophic control of 16S acetylcholinesterase at the vertebrate neuromuscular junction
Authors: Fernandez Hugo L. , Duell Myron J. , Festoff Barry W. 
Published: January 2005

AbstractEndplate 16S acetylcholinesterase (16S‐AChE) from rat anterior gracilis muscle was assessed, 6 hr to 10 days after denervation, by velocity sedimentation analysis on linear sucrose gradients. The innervating obturator nerve was transected either close (1‐2 mm, short stump) or far (35‐40 mm, long stump) from the muscle. In both instances, the activity of 16S‐AChE gradually decreased and reached approximately the same level (10%‐20% of control) by 6 days after denervation. However, enzymatic decay started considerably earlier in short stump (12‐24 hr) as compared to long stump (4‐5 days) preparations, i.e., the time of onset of 16S‐AChE loss depended on the length of nerve that remained attached to the muscle. Whether this result extended to other AChE molecular forms (10S, 4S) in muscle endplates could not be determined because, in contrast to 16S‐AChE, these forms were also detected in red blood cells (4S) and plasma (10S). Only small amounts of 16S‐AChE were found in intact obturator nerves (1/100 of that in gracilis endplate regions). Thus a faster depletion of enzyme from shorter nerve stumps after axotomy could not entirely account for the substantial effect of nerve stump length on 16S‐AChE. Since muscle contraction ceases immediately following nerve transection, regardless of nerve stump length, the results can be ascribed to the lack of some neural influence other than nerve‐evoked muscle activity. The present findings are consistent with the view that maintenance of 16S‐AChE at neuromuscular junctions primarily depends on regulatory substances which are conveyed by axonal transport and released from nerve terminals.
Photomechanical migrations of pigment granules along the retinula cells of the crayfish
Authors: Frixione Eugenio , Aréchiga Hugo , Tsutsumi Victor 
Published: January 2005

AbstractThe light‐dependent migrations of proximal pigment granules along the photoreceptors of the crayfish compound‐eye were studied in isolated retinas and eyestalks. The extent and kinetics of movement in each direction were found quantitatively equivalnt to those observed in the organ in situ. These and other features make these cells to appear as intrinsically independent pigmentary effectors, directly responsive to light. During dark adaptation (DA) the pigment migrates away from the cell nucleus and accumulates along the axon in two distinct steps. Each step constitutes half of the total distance of about 180 μm and proceeds at 0.30 μm/sec. Only prolonged metabolic impairment inhibited the first phase, while the second was blocked by hypoxia, cyanide, colchicine, and D2O. The maintenance of a full DA position was also shown to be highly dependent upon metabolism. Light incidence on DA eyes is followed by an apparently monophasic expansion of the pigment from the axon towards the perikaryal region at 0.38 μm/sec. This movement was not affected by any of the foregoing agents and seems to be a passive relaxation process. Cytochalasin B had no effect on either motion. The migration in either direction has an exponential time course and is temperature dependent. Electron microscopy revealed two separate patterns of cytoplasmic organization corresponding to the cell areas where the two phases of DA occur. In the region close to the nucleus the pigment appears irregularly scattered, whereas in the axon the granules are situated around a thick longitudinal bundle of microtubules. These results suggest the existence of two different mechanisms of pigment granule translocation operating in two separate regions of the retinula cell.
Subcellular particles involved in the translocation of proteins in rat brain
Authors: White Fredric P. 
Published: January 2005

AbstractProtein translocation systems which are inhibited by vinblastine, colchicine, and low calcium concentrations have been found in the cells of the brain slice. The early steps in the translocation pathways of newly synthesized protein have been studied by use of a double‐label experiment in conjunction with subcellular fractionation. Certain subcellular particles have been positioned on the pathways with reference to vinblastine‐sensitive translocation steps. There appears to be many subcellular organelles that are located downstream from a vinblastine‐sensitive translocation step and which receive significant quantities of translocated protein within an hour of its synthesis. Some of these organelles co‐enrich with the enzyme marker 5′‐AMPase. Myelinated axons, Golgi derived vesicles, and smooth and rough endoplasmic reticulum all are enriched in fractions which contain a net vinblastine‐sensitive importation of protein. The major particles, which lie upstream from a vinblastine‐sensitive translocation step and are net exporters of protein on this system, are found in a brain capillary fraction. It is suggested that the most likely exporter present in these capillaries are the end feet of astrocyte glial cells.
Bidirectional axonal transport of 16S acetylcholinesterase in rat sciatic nerve
Authors: Fernandez Hugo L. , Duell Myron J. , Festoff Barry W. 
Published: January 2005

AbstractAxonal transport of the 16S molecular form of acetylcholinesterase (16S‐AChE) in doubly ligated rat sciatic nerves was studied by means of velocity sedimentation analysis on sucrose gradients. This form of AChE was selectively confined to motor, and not to sensory, fibers in the sciatic nerve, where it represented 3–4% of total AChE. Its activity increased linearly with time (4–20 hr) in nerve segments (7 mm) proximal to the central ligature (4.5 mU/24 hr) and distal to the peripheral ligature (2.0 mU/24 hr). From the linear rates of accumulation of 16S‐AChE, we conclude that the enzyme is conveyed by anterograde and retrograde axonal transport at velocities close to those previously defined for the movement of total AChE (410 mm/day, anterograde; 220 mm/day, retrograde). The transport of AChE molecular forms, other than the 16S form, could not be resolved presumably due to their presence in blood as well as at extraaxonal sites. The present findings are consistent with the view that in rat sciatic nerve most, if not all, of the small portion of total AChE (approximately 3%) which is transported may be accounted for by 16S‐AChE.
Intensity and motion responses of giant vertical neurons of the fly eye
Authors: Soohoo Spencer L. , Bishop Lewis G. 
Published: January 2005

AbstractThere are nine “giant vertical” neurons in the lobula plate of the fly optic lobe. Intracellular recordings were obtained from the three most peripheral of these cells. These cells respond to a light flash with graded changes in the membrane potential. The response consists of an “on” transient, a sustained depolarization, an increase in membrane potential fluctuations, and an “off” transient. Signal averaging showed that only the “on” and “off” transients are correlated to the stimulus. A pattern of horizontally oriented stripes moving in the vertical direction evokes a response larger than the response to a stationary pattern. The response is most sensitive to vertical movement; motion in the downward direction evokes a net membrane potential depolarization, and upward motion results in a net hyperpolarization. We conclude that the giant vertical cells function primarily as vertical motion detectors and that the direction of the motion is encoded in the polarity of the shift in the membrane potential.
Cholesterol is a component of the rapid phase of axonal transport
Authors: Blaker William D. , Toews Arrel D. , Morell Pierre 
Published: January 2005

AbstractTwenty‐two‐day‐old rats were injected intraocularly with [3H]acetate and killed between 1 hr and 35 days later. Cholesterol was isolated from the retinas, optic tracts, lateral geniculate bodies, and superior colliculi. Within the retina, radioactivity was rapidly incorporated into cholesterol with maximal labeling present one hour after injection. Transported labeled cholesterol (contralaterally corrected for systemic background labeling) was present in the superior colliculus by three hours. Radioactive cholesterol accumulated in all visual strctures throughout the 35‐day period, but the rate of accumulation was maximal at about the time of arrival of the initial pulse of radioactivity. Colchicine treatment of the retina blocked transport of cholesterol but not its synthesis by the retina. The results indicate that cholesterol is rapidly transported in the visual system and also released from the retina for a prolonged period after its synthesis.
Block of axoplasmic transport in vitro by vinca alkaloids
Authors: Chan S. Y. , Worth R. , Ochs S. 
Published: January 2005

AbstractThe three potent antimitotic vinca alkaloids: vincristine (VCR), vinblastine (VLB), and vindesine (VDS) were compared for their effect in blocking axoplasmic transport in vitro using a desheathed preparation of the peroneal branch of cat sciatic nerve. A range of vinca alkaloid concentrations from 1–100μM was examined. The relative order of potency in blocking axoplasmic transport was VCR > VLB > VDS at a concentration of 25μM. At the higher concentrations block occurred so rapidly that a statistically significant difference between these agents could not be obtained. The relation of vinca block ot the transport mechanism is discussed.
Dynamic properties of cockroach cercal “bristlelike” hair sensilla
Authors: Buño W. , Monti‐Bloch L. , Crispino L. 
Published: January 2005

AbstractResponses of cercal “bristlelike” hair sensilla (BHS) on Periplaneta americana L. to movement were investigated by recording generator (GP) and spike potentials with an extracellular pipette electrode which held the bristle by its tip. BHSs had no resting discharge, were purely phasic, with sensitivity only to stimulus transitions. They were directionally sensitive. Sinusoidal analysis suggested, to a first approximation because of the important nonlinearities, the behavior of a first‐order lead system with corner frequencies distributed between 8 and 20 Hz. Responses elicited by step‐ and ramplike displacements were roughly in accord with the above behavior. Nonlinearities occurred both at GP level and at the level of spike generation. The phasic and the nonlinear behaviors at GP level may have a mechanical origin. The lack of spontaneous activity and the threshold nature of the spike generator account for other nonlinearities. The operation of BHS could be separated conceptually into a linear element followed by nonlinear elements. A computer simulation based on these concepts showed a close fit to the biological responses.
Dynamic properties of cockroach cercal “threadlike” hair sensilla
Authors: Buño W. , Monti‐Bloch L. , Mateos A. , Handler P. 
Published: January 2005

AbstractInput‐output (I‐O) relationships were studied in cercal “thread‐hair” sensilla (THS) on Periplaneta americana L. by recording from individual axons of THS while displacing the corresponding hair with a galvanometric device. Sinusoidal analysis was attempted and pulse‐ and ramplike displacements were then tested. The effects of stimulus orientation were also investigated. THS were spontaneously active and purely phasic and did not respond to sustained displacements. With small sinusoidal displacements (<30°) they behaved as a linear, secondorder lead system sensitive to velocity. With larger amplitudes, however, they exhibited prominent nonlinear features with minimal consequences of displacements at the extremes. Responses to other waveforms indicated secondorder response components. THS were directionally sensitive. Phasic behavior and the nonlinearities may be due to mechanical properties at the base of the hair. The spike‐firing threshold may also contribute. Resting activity appears to be due to neuronal factors since it was not abolished by preventing hair movements. Transducer operations were simulated in a digital computer.
Pineal glands of immature rats: Rise and fall in N‐Acetyltransferase activity in vitro
Authors: Brammer Mildred , Binkley Sue 
Published: January 2005

AbstractN‐acetyltransferase activity in the pineal glands of immature rats (12‐14 days old) shows a spontaneous rise and fall when the glands are placed in organ culture. The peak of the 28‐fold change occurs 5–16 hr after the cultures are initiated. This observation can be interpreted in two ways: (1) the pup pineal gland is responding to norepinephrine released when nerve endings degenerate in culture, or (2) the pup pineal gland has an innate ability which is responsible. Whatever the mechanism, the phenomenon is associated with the development of pineal gland function since pineal glands of adult rats do not show a spontaneous rise and fall in identical experiments.
Interneurons of the crayfish brain: The relationship between dendrite location and afferent input
Authors: Glantz Raymon M. , Kirk Mark , Viancour Terry 
Published: January 2005

AbstractThis study was undertaken to examine the relationship between the structure and function of the descending interneurons of the crayfish brain. In particular, the dendritic fields were examined to ascertain if the location of an interneuronal dendrite in any of the six cerebral hemineuromeres (which subserve specific sensory modalities) is a necessary or sufficient condition to determine the functional and/or synaptic input to the interneuron. If a neuron projects a dendrite to a hemineuromere of the deutocerebrum or tritocerebrum, the neuron derives sensory input from the corresponding afferent root in 95% of our observations. Most of these inputs (86%) contain at the least a monosynaptic component. Conversely, if a cell derives monosynaptic input from any one of three of the four deutocerebral and tritocerebral roots tested, it has a corresponding dendrite (in 98% of our observations) in the appropriate hemineuromere. Input from the contrlateral antennal nerve is an exception to this rule. The presence of a dendrite in the protocerebrum is not sufficient for predicting detectable visual input, but every instance of detectable visual input is associated with a protocerebral dendrite. Polysynaptic inputs are frequently (42%) not associated with corresponding dendrites. In neurons that were repeatedly dye filled in different animals, we observed significant variation only in the number and precise location of the smaller secondary and tertiary neurites. This variation rarely influenced the subset of sensory lobes innervated by the neuron.
In vivo electrical stimulation alters sensitivity of the brain (Na+ + K+)ATPase toward inhibition by vanadate
Authors: Křivánek Jiři 
Published: January 2005

AbstractIt has recently been shown that electrical stimulation of the brain cortex in vivo blocks invasion of cortical spreading depression (SD) into the stimulated area. The effect has been interpreted as a result of activating a K+ pumping mechanism that prevents the accumulation of this ion in the extracellular space to the high levels required for SD propagation. In the present experiments (Na+ + K+)ATPase activity was determined in the electrically stimulated region of the rat brain cortex. When ATP preparations containing vanadate were used as substrate, elevation of K concentration in the assay medium from 2 to 20 μM inhibited enzyme activity in homogenates from the normal cortex but not that from homogenates of the electrically stimulated cortical region. With vana‐date‐free ATP (Boehringer) as a substrate, slight stimulation by 20 μM K+ has been observed in both cases. Vanadate (0.25 μM) added to the assay medium containing Boehringer ATP and 20 μM K+ inhibited ATPase activity from the normal cortex but not that from the stimulated cortical area. Electrical stimulation may activate (Na+ + K+)ATPase at least partly by diminution of its susceptibility toward the inhibitory action of vanadate.
Axonal branching pattern and coupling mechanisms of the cerebral giant neurones in the snail, lymnaea stagnalis
Authors: Goldschmeding J. T. , van Duivenboden Yvonne A. , Lodder J. C. 
Published: January 2005

AbstractThe axonal branching pattern of the two cerebral giant neurones (CGCs) of Lymnaea stagnalis was studied with intrasomatically applied horseradish peroxidase. The cells are symmetrical. Each CGC projects to the ipsilateral n. labialis medius and n. arteriae labialis, the subcerebral commissure, and to all ipsi‐ and contralateral buccal nerves. The contralateral buccal nerves are reached via the ipsilateral cerebro‐buccal connective and the buccal commissure. The CGC fire action potentials 1:1 in a driver‐follower relationship. Each cell is capable of both driving and following. The relationship depends on the membrane potentials of the somata. In driving CGC spikes are initiated in a cerebral spike trigger zone located near the soma. In following cells spikes are initiated in a distal zone located in the buccal ganglia. The buccal zone is only affected by the partner CGC. CGC are synchronized by three coupling mechanisms: mutual excitatory chemical synapses, electrotonic coupling, and common input. The chemical and electrotonic connections are located in the buccal ganglia. All spikes are relayed to the partner cell via the chemical synapses. The electrotonic coupling improves the efficiency of the chemical synapses. The dual connection selectively synchronizes the CGC‐axonal spikes from each side of the buccal mass. Common excitatory input affects the cerebral spike trigger zones and can initiate simultaneous spikes in both cells. This results in bilateral synchrony of spikes in the CGC‐axons in both the buccal and the lip nerves.
Serotonergic inhibition of afterdischarge in peptidergic bag cells
Authors: Jennings K. R. , Host J. J. , Kaczmarek L. K. , Strumwasser F. 
Published: January 2005

AbstractThe neuroendocrine bag cells of Aplysia generate a long‐lasting afterdischarge causing the release of the peptide egg‐laying hormone (ELH) into the hemolymph (Stuart and Strumwasser, 1980). This afterdischarge activity can be elicited in vitro by electrical stimulation of a pleurovisceral connective (PVC) nerve. It has been shown previously that bag cell afterdischarge and egg‐laying behavior can also be induced by a purified neuroactive peptide isolated from the atrial gland in the reproductive tract (Heller et al., 1980). The authors find that the afterdischarge can be inhibited in a dose‐dependent manner by the extracellular application of low concentrations of serotonin (5 × 10−7 M). This inhibitory action of serotonin is blocked by the serotonin antagonist D‐butaclamol. Serotonin has been found to prevent egg laying (and associated behaviors) induced by injection of this atrial gland peptide in vivo but not that induced by injection of ELH. Afterdischarge activity in bag cells consists of a short initial phase during which the spike frequency is high and a longer, secondary phase in which the spike frequency is much lower (Kupfermann and Kandel, 1970). Intracellular recordings during serotonin inhibition of afterdischarge indicate significant decreases in spike amplitude (15%) and duration (18%) compared with controls. In addition, the latency and threshold of directly elicited spikes, in the absence of afterdischarge, were increased considerably as a result of serotonin. Arguments are presented from these data that serotonin may be preventing the conductance decrease associated with the long‐lasting second phase of afterdischarge and that this effect of serotonin can be overcome by application of the potassium channel blocker tetraethylammonium (TEA). Although a serotonergic input to the bag cell neurons has not yet been described, the pleurovisceral connective nerves, known to contain bag cell process, have the highest concentration of serotonin receptors of any nervous tissue in Aplysia (Drummond, Bucher, and Levitan, 1980). It remains to be determined whether these represent serotonergic synapses on bag cell processes. The authors speculate that serotonin, considered a transmitter mediating sensitization (arousal) in other systems in Aplysia, may act to suppress an ongoing peptide hormone release, which would have triggered a behavior program in the freely behaving animal, thus allowing some degree of behavioral plasticity as a result of changed conditions in the external environment.
Nickel chloride for intracellular staining of neurons in insects
Authors: Delcomyn Fred 
Published: January 2005

AbstractThe advantages of nickel chloride (NiCl2) for intracellular staining of insect neurons are described. Nickel shares with cobalt the features of rapid migration, easy precipitation, and the capability of being silver‐intensified. But, nickelfilled electrodes also have lower average resistances and pass current more readily than comparable electrodes filled with cobalt, making it the ion of choice for intracellular marking in many instances.
Neuritic growth and neuroma formation by an isolated molluscan ganglion
Authors: Stamler J. F. , Kater S. B. , Murphy A. D. , Bulloch A. G. M. 
Published: January 2005

AbstractThe isolated, paired buccal ganglia of the snail Helisoma trivolvis were cultured in vivo (i.e., in host snails) for periods up to 377 days. Such ganglia typically become enveloped in a white mass of fibrous tissue which reaches a maximum plateau of size within four weeks. The scanning electron microscope revealed the newly formed tissue to be composed of fine fibers which also pervaded the neuropil. Injection of individual neurons with Lucifer Yellow CH filled many new neurites within the tissue mass. It is concluded that these masses are largely of neuronal origin and they are therefore designated as neuromas. The maximum size of neuromas may be limited by intrinsic mechanisms which limit neuronal volume.
Age‐diminished motor neuronal function of central neuron L7 in Aplysia
Authors: Peretz Bertram , Ringham Gary , Wilson Randall 
Published: January 2005

AbstractThe efficacy of central neuron L7 to elicit gill pinnule contractions was tested in mature and old Aplysia. The difference in age between groups was no less than 70 days and as much as 150 days. Spike trains in L7 were necessary to elicit pinnule contractions in both age groups. Spike rates of 8 spikes per second and higher elicited pinnule contractions that were significantly smaller in old than in mature animals. Synaptic acitivity in the pinnule muscles innervated by L7 was recorded extracellularly during contractions, and it was significantly less facilitated by spike trains in old as compared to that in mature Aplysia. This suggests that the reduction of facilitated synaptic transmission between L7 and pinnule muscles results in diminished motor neuron function.
Testosterone increases acetylcholine receptor number in the “levator ani” muscle of the rat
Authors: Bleisch William V. , Harrelson Allan L. , Luine Victoria N. 
Published: January 2005

AbstractThe “levator ani” muscle of male rats provides a neuromuscular system in which both the muscle and its motoneurons have high levels of androgen receptors. Two weeks of castration caused a 48% loss of acetylcholine receptors in this muscle. One week of testosterone propionate injections initiated one week after castration increased receptor number by 27% over untreated castrate levels. These changes paralleled changes in muscle protein content. In contrast, castration and testosterone treatments of castrates had no effect on total, Triton X‐100‐extractable acetylcholinesterase activity. This system may provide a useful model of synaptic plasticity.