bluuebunny/crossref_metadata_2025_split huggingface dataset:
The history of the discovery of the nerve growth factor
Authors: Hamburger Viktor 
Published: January 2005

AbstractThe Nerve Growth Factor (NGF) is the progenitor of a family of growth factors which is still expanding. The history of its discovery is very colorful; it is a rare combination of scientific reasoning, intuition, fortuities, and good luck. In addition, I believe that the collaboration of three scientists with very different backgrounds contributed to the success: I had grown up in a laboratory of experimental embryology, Dr. Levi‐Montalcini came from neurology, and Dr. Stanley Cohen was from biochemistry.The decision where to begin the history of a discovery is always arbitrary. I shall give my reasons why I begin this story with my wing bud extirpations on chick embryos and the analysis of the effects of the operation on the development of spinal nerve centers, published in 1934. Of course, I am aware of the fact that the analysis of neurogenesis had been pioneered by Dr. R. G. Harrison and his students at Yale University since the beginning of this century. It should be mentioned that their experiments had been done on amphibian embryos. My own interest in problems of neurogenesis dates back to my Ph.D. thesis in the Zoology Department of Professor H. Spemann at the University of Freiburg in (the Federal Republic of) Germany; it dealt with the influence of the nervous system on the development of limbs in frog embryos. After I had obtained some inconclusive results I did the crucial experiment of producing nerveless legs. I removed the lumbar part of the spinal cord and the spinal ganglia before the outgrowth of nerve fibers. The nerveless legs developed normally in every respect, but the muscles atrophied eventually.
Axial level‐dependent differences in size of avian dorsal root ganglia are present from gangliogenesis
Authors: Goldstein Ronald S. 
Published: January 2005

AbstractDorsal root ganglia (DRG) form from neural crest cells that colonize the rostral sclerotomes of the somites of the trunk of higher vertebrates. Differences in sensory field size and innervation density are reflected by the size of the ganglia at different axial levels. Some of the position‐dependent differences in ganglionic size derives from asymmetry in embryonic programmed cell death, when more DRG neurons die at non‐limb‐innervating levels than at the levels that innervate the limbs. I have now examined early chick embryos determine whether there is asymmetry in DRG size at the time of their condensation at stage 20 [embryonic day (E) 3], before the onset of cell death. Ganglia in brachial segments 14 and 15 are more than 80% larger on average than those in cervical segments 5 and 6 at this stage of development. This difference in volume is due to increased numbers of cells in the brachial sensory ganglia. Several other morphometric parameters of the DRG and sclerotomes were then determined. The rostro‐caudal length was found to be significantly greater for brachial ganglia. The greater length of the brachial ganglia was found to be correlated with (1) a greater length of brachial than cervical sclerotomes and (2) the occupation by brachial ganglia of a larger proportion of the rostro‐caudal extent of the sclerotome. These results demonstrate that the mature pattern of axial differences in ganglionic size are foreshadowed by a pattern set during the period of gangliogenesis, which is then further sculpted by apoptosis. This initial axial asymmetry in size preceding cell death parallels that recently shown for the development of the ventral motor column. Thus the sensory ganglia, like the somites, have distinct axial‐position‐dependent characteristics from their outset, characteristics that are not dependent on cell death resulting from competition for target‐derived survival factors as was previously thought. DRG positional identities, like their segmentation, may be imposed by the paraxial mesoderm or may alternatively be intrinsically determined as is the case for the rhombomeres of the hindbrain. © 1993 John Wiley & Sons, Inc.
Planar and vertical induction of anteroposterior pattern during the development of the amphibian central nervous system
Authors: Doniach Tabitha 
Published: January 2005

AbstractIn amphibians and other vertebrates, neural development is induced in the ectoderm by signals coming from the dorsal mesoderm during gastrulation. Classical embryological results indicated that these signals follow a “vertical” path, from the involuted dorsal mesoderm to the overlying ectoderm. Recent work with the frog Xenopus laevis, however, has revealed the existence of “planar” neural‐inducing signals, which pass within the continuous sheet or plane of tissue formed by the dorsal mesoderm and presumptive neurectoderm. Much of this work has made use of Keller explants, in which dorsal mesoderm and ectoderm are cultured in a planar configuration with contact along only a single edge, and vertical contact is prevented. Planar signals can induce the full anteroposterior (A‐P) extent of neural pattern, as evidenced in Keller explants by the expression of genes that mark specific positions along the A‐P axis. In this review, classical and modern molecular work on vertical and planar inductionwill be discussed. This will be followed by a discussion of various models for vertical induction and planar induction. It has been proposed that the A‐P pattern in the nervous system is derived from a parallel pattern of inducers in the dorsal mesoderm which is “imprinted” vertically onto the overlying ectoderm. Since it is now known that planar signals can also induce A‐P neural pattern, this kind of model must be reassessed. The study of planar induction of A‐P pattern in Xenopus embryos provides a simple, manipulable, two‐dimensional system in which to investigate pattern formation. © 1993 John Wiley & Sons, Inc.
Sexual differences in the numerical density of synaptic profiles of developing rat visual cortex
Authors: Muñoz‐Cueto José Antonia , Ruiz‐Marcos Antonio 
Published: January 2005

AbstractAxo‐dendritic synaptic profiles were quantified along the whole depth of the visual cortex of 10‐day‐old male and female rats. In both sexes the numerical density of synaptic profiles on spine‐like structures was greater than the numerical density of synapses on dendritic shafts. Females had a significantly greater numerical density of synaptic profiles on spine‐like structures, than did males at a distance of 200–400 and 500–600 μm from the pia surface, which corresponds to layers II–III and IV of the cortex, respectively. A small percentage (2%–4%) of spine‐like structures received two presynaptic terminals. This type of double synapses was three times more abundant in females. No sex differences were found in the numerical density of synapses on dendritic shafts in any cortical layer. 1994 John Wiley & Sons, Inc.
Identification of a 70 kD protein with sequence homology to squid neurofilament protein in glial cells of the leech CNS
Authors: Lüthi Theres E. , Brodbeck Daniela L. , Jenö Paul 
Published: January 2005

AbstractA monoclonal antibody G39, generated against a protein extract of leech central nervous system, labels specific cell types in adult, embryonic, and regenerating preparations. The antibody stained glial cells, microglial cells, and connective tissue cells, but nor neurons or muscle on cryosections. The staining pattern resembled that of an intracellular network. Affinity purification of the antigen revealed a 70 kD protein. Peptide sequencing showed significant homology of a stretch of 15 amino acids to squid neural filament protein. The same mAb G39 delineated glial cells as they formed during development of the CNS and showed that the giant neuropil glial cells appear before those in the packets. The antigen recognized by mAb G39 represents a nonneuronal intermediate filament of the leech Hirudo medicinalis found in various cell‐types such as glia, microglia, and some cells of the connective tissue. 1994 John Wiley & Sons, Inc.
OS9: A novel olfactory gene of Drosophila expressed in two olfactory organs
Authors: Raha Debasish , Carlson John 
Published: January 2005

AbstractA novel olfactory gene, OS9, has been identified in Drosophila by subtractive hybridization. OS9 transcripts have been detected in the third antennal segment, the primary olfactory organ in Drosophila, and in the maxillary palp, which has recently been shown to have olfactory function. The OS9 gene thus represents a molecular link between two distinct olfactory tissues in Drosophila. Little if any OS9 expression has been detected in other segments of the antenna or in other tissues examined. The gene is located in region, 38AB on the cytogenetic map. OS9 encodes a protein of 159 amino acids, which contains a putative leucine zipper. Polyclonal antibodies raised against the C‐terminal half of the encoded protein react with a 24 kD antennal protein. Antisera raised against both C‐terminal and N‐terminal halves of the OS9 protein appear to react with cell nuclei in both the third antennal segment and the maxillary palp; interestingly, both antisera also stain cells in the head, including photoreceptor nuclei, as if OS9 were an olfactory‐specific member of a family of nuclear proteins, possibly transcription factors. 1994 John Wiley & Sons, Inc.
Female marsh wrens do not provide evidence of anatomical specializations of song nuclei for perception of male song
Authors: Brenowitz Eliot A. , Nalls Belinda , Kroodsma Donald E. , Horning Cynthia 
Published: January 2005

AbstractIn songbirds the forebrain nuclei HVC (high vocal center) and RA (robust nucleus of the archistriatum) are larger in individuals or species that produce larger song repertoires, but the extent to which the size of these nuclei reflects a need for either producing or perceiving large repertoires is unknown. We, therefore, tested the hypothesis that species differences in the size of song nuclei reflect a commitment of “brain space” to the perceptual processing of conspecific song. The two species of marsh wren (Cistothorus palustris western and eastern) provide a good test case. Western males produce larger song repertoires, and have larger HVC and RA than do eastern males. Female marsh wrens do not sing, and if they use their song nuclei to assess conspecific male song repertoires, then we predicted that measurable cellular and nuclear parameters of HVC and RA would be greater in western than eastern female wrens. For males we confirmed that the volumes of HVC and RA, and cellular parameters of HVC, are greater in western than in eastern birds. These nuclei were also considerably larger in males than in conspecific females. Western and eastern female wrens, however, did not differ in any measured parameters of HVC or RA. Females of these wren species thus do not provide any direct evidence of anatomical specializations of song nuclei for the perceptual processing of conspecific male song. 1994 John Wiley & Sons, Inc.
Spontaneous Ca2+ transients in developing hippocampal pyramidal cells
Authors: Dailey Michael E. , Smith Stephen J. 
Published: January 2005

AbstractTo determine the spatiotemporal pattern of hippocampal pyramidal cell activity during development, we examined cytosolic Ca2+ dynamics in tissue slices derived from early postnatal rats. After a brief (12–60 h) culture period, slices were stained with a calcium‐sensitive dye, Fluo‐3. Fluorescence imaging of the Fluo‐3‐stained slices with a scanning laser confocal microscope afforded simultaneous observation of many cells at high spatial resolution. Time‐lapse imaging revealed spontaneous Ca2+ transients in the somata and dendrites of many pyramidal cells in areas CA1 and CA3. For the most part, Ca2+ activity in neighboring pyramidal cells appeared to be uncorrelated, although we occasionally observed synchronous Ca2+ transients in adjacent cells. The transients were blocked by both tetrodotoxin (1 μM) and a mixture of the glutamate receptor antagonists, APV (50 μM) + CNQX (10 μM). Thus, spontaneous Ca2+ transients appear to be a consequence of activity‐dependent release of glutamate acting postsynaptically through ionotropic glutamate receptors. Although γ‐aminobutyric acid (GABA) is thought to be an excitatory neurotransmitter during hippocampal development (Cherubini et al., 1991, Trends Neurosci. 14(12):515–519), the spontaneous Ca2+ transients were not blocked by the GABAA receptor antagonist picrotoxin (100 μM). Furthermore, application of GABA (50 μM) abolished the spontaneous Ca2+ events, possibly via GABAB receptor‐mediated inhibition of postsynaptic cells. The present results join other recent observations suggesting that isolated neural tissues support spontaneous activity, although the patterns and mechanisms of the activity reported here appear to differ from those of previous studies. Differences in the patterns of spontaneous activity during development may contribute to variations in the functional organization of different regions of CNS tissue. 1994 John Wiley & Sons, Inc.
Intracellular calcium mobilization and neurite outgrowth in mammalian neurons
Authors: Kocsis Jeffery D. , Rand Mark N. , Lankford Karen L. , Waxman Stephen G. 
Published: January 2005

AbstractCultured adult rat dorsal root ganglion (DRG) neurons were used to study depolarization‐induced Ca2+ mobilization and the effects of intracellular Ca2+ depletion on neurite outgrowth. Cytoplasmic and nuclear Ca2+ signals were visualized in dissociated DRG neurons using confocal scanning laser microspcopy and the Ca2+ indicator dye fluo‐3. The depolarization‐induced Ca2+ signals were highest in neurons during the first few days in culture, prior to neurite extension; during this time nuclear signals exceeded those of the cytoplasm severalfold. After several days in culture, neurons began to arborize, depolarization‐induced Ca2+ signals became attenuated, and nuclear signals no longer exceeded those of the cytoplasm. Elevated Ca2+ signals were dependent upon both Ca2+ influx and intact intracellular Ca2+ stores, indicating that the signals are generated by calcuim‐induced calcium release (CICR). Thapsigargin, an endoplasmic reticulum Ca2+ ATPase inhibitor, depleted intracellular Ca2+ stores and blocked the induction of the large nuclear Ca2+ signals. Treating DRG neurons briefly with thapsigargin (200 nM for 20 min) shortly after plating reduced subsequent neuritogenesis, impyling that intact Ca2+ stores are necessery for initiating neurite outgrowth. Immunostaining of DRG neurons with antibodies to Ca2+ /calmodulin‐dependent kinase II (CaM kinase II) demonstrated that this enzyme is present in the nucleus at early times in culture. These observations are consistent with the idea that CICR triggered by Ca2+ entry subsequent to depolarization may elicit neurite outgrowth by activating nuclear enzymes appropriate for such outgrowth. © 1994 John Wile & Sons, Inc.
Resonant activation of calcium signal transduction in neurons
Authors: Fields R. Douglas , Nelson Phillip G. 
Published: January 2005

AbstractThe relevant parameters of calcium fluxes mediating activation of immediate‐early genes and the collapse of growth cones in mouse DRG neurons in response to action potentials delivered in different temporal patterns were measured in a multicompartment cell culture preparation using digital flourescence videomicroscopy. Growth cone collapse was produced by trains of action potentials causing a large rise in [Ca2+]i, but after chronic exposure to patterned stimulation growth cones regenerated and became insensitive to the stimulus‐induced increase in [Ca2+]i. Calcium reached similar peak concentrations, but the [Ca2+]i increased more slowly than in naive growth cones (time constant of 6.0 s versus 1.4 s in naive growth cones). Semiquantitative PCR measurements of gene expression showed that pulsed stimulation delivered at 1‐min intervals for 30 min induced expression of c‐fos, but the same total number of action potentials delivered at 2‐min intervals failed to induce c‐fos expression, even though this stimulus induces a larger peak [Ca2+]i than the effective stimulus pattern. The experiments suggest that the kinetics of calcium fluxes produced by different patterns of stimulation, and changes in the kinetics of calcium flux in neurons under different states of activation, are critical in determining the effects of action potentials on growth cone motility or expression of IE genes during development of neuronal circuits. We propose that differences in kinetics of individual reactions in the stimulus–response pathway may lead to resonance of activation in the neuron, such that certain processes will be selectively activated by particular temporal patterns of stimulation. 1994 John Wiley & Sons, Inc.
The plasma membrane calcium pump: Functional domains, regulation of the activity, and tissue specificity of isoform expression
Authors: Carafoli Ernesto , Stauffer Thomas 
Published: January 2005

AbstractThe plasma membrane Ca2+ pump is responsible for the fine regulation of the intracellular Ca2+ level and is thus involved in the control of several cellular processes. The activity of the pump is regulated by a multiplicity of mechanisms, among which are calmodulin, acidic phospholipids, kinase‐mediated phosphorylation, or an oligomerizatin process. The C‐terminal part of the molecule interacts with the region of the pump close to the active site, leading to the decrease of the activity in the resting state. Four genes coding for different isoforms of the plasma membrane Ca2+ ATPase are known in humans. Isoform 1 and 4 represent housekeeping isoforms, whereas isoforms 2 and 3 are only present in specialized tissues. The variability of the protein in further increased by alternative RNA slicing at two sites (A, C). Alternative splicing occurs within (splice site C) or near (splice site A) regions coding for regulatory domains of the protein. In all isoforms a corresponding splice form exists at both splice sites. These common splice forms are present in all tissues, whereas isoform unique splice forms are normally only present in specialized tissues. In neuronal tissues all isoforms and almost the complete set of splice forms are found. The transcripts of the different isoforms are distributed in a region‐specific manner in neuronal tissues. 1994 John Wiley & Sons, Inc.
Acceleration by NMDA treatment of visually induced map reorganization in juvenile Xenopus after larval eye rotation
Authors: Bandarchi Jafar , Scherer Warren J. , Udin Susan B. 
Published: January 2005

AbstractEach tectal lobe of Xenopus forgs receives two topographic maps, one via the ipsilateral eye and one via the contralateral eye. The alignment of the ipsilateral map with the contralateral map depends upon bincoular visual input during a critical period that extends from late tadpole to early juvenile stages. Rotation of one eye during the critical period leads to reorganization of the ipsilateral map, which eventually comes back into alignment with the contralateral map despite the abnormal eye position. The ipsilateral eye's map initially develops as if there had been no alteration in eye position; there is a delay of 4–6 weeks before reorganization can be detected by electrophysiological mapping. In this paper, the possible role of the NMDA receptor in the delay in reorganization is addressed. The degree of NMDA receptor activation may need to be above some threshold level to trigger reorganization. If NMDA receptor activation normally is below that level until after the first month postmetamorphosis, then exogenous NMDA might boost the process sufficiently to start the reorganization process sooner than usual. In order to test this possibility, the left eye of tadpoles was rotated and NMDA was applied to the right tectal lobe for 3–5 weeks, starting at 1 week postmetamorphosis. Electrophysiological mapping demonstrated that reorganization takes place more rapidly than in untreated forgs or frogs treated with vehicle only. This result is consistent with the interpretation that the activation of the NMDA receptor is a rate‐limiting step in the activity‐dependent matching of binocular maps in Xenopus tectum. 1994 John Wiley & Sons, Inc.
Cell adhesion molecules in the early developing mouse retina: Retinal neurons show preferential outgrowth in vitro on L1 but not N‐CAM
Authors: Hankin Mark H. , Lagenaur Carl F. 
Published: January 2005

AbstractBoth L1 and N‐CAM are present on optic axons early in the developing mouse retina and optic nerve. In in vitro assays on substrates of purified cell adhesion molecules cells derived from E13 mouse retinae showed vigorous neurite extension on L1 but not on N‐CAM. Although retinal neurons on N‐CAM showed only limited attachment to the substrate, they were able to form lamellipodia immediately around the cell perimeter. In contrast, similarly derived cortical cells showed extensive neurite outgrowth on both substrates. Under these culture conditions, nearly all of the L1 and N‐CAM present in the cell membrane appeared to be sequestered on the lower surface of the growth cones and neurites, indicating that most of these cell adhesion molecules were involved in homophilic interactions. Our results suggest differential roles for L1 and N‐CAM in intitiation and establishment of the optic pathway. © 1994 John Wiley & Sons, Inc.
Influence of interganglionic interactions on steroid‐mediated dendritic reorganization and death of proleg motor neurons during metamorphosis in Manduca sexta
Authors: Weeks Janis C. , Davidson Seana K. 
Published: January 2005

AbstractIn Manduca sexta, the larval abdominal prolegs and their muscles degenerate at pupation. The proleg motor neurons undergo a period of dendritic regression, after which a specific subset of them dies. The surviving motor neurons undergo dendritic outgrowth during pupal‐adult development, and most die after adult emergence. All of these events are regulated hormonally by ecdysteroids and juvenile hormone, but interactions of the motor neurons with other cells may potentially contribute as well. To investigate the possible influence of interganglionic neural interactions, we chronically isolated individual abdominal ganglia by severing the adjacent rostral and caudal connectives in the larval stage. Subsequent metamorphic changes in proleg motor neurons were examined in the isolated ganglia and ganglia adjacent to the isolated ganglia. Two abnormalities were observed: (1) some imprecision in the timing of motor neuron death, both at pupation and after adult emergence, and (2) the growth of ectopic neurites outside the neuropil boundaries during pupal‐adult development (in ganglia with or without neuromas caused by connective transections). Other aspects of proleg motor neuron metamorphosis, including the segment‐specific death of motor neurons at pupation, were the same as that in intact and sham‐operated insects. Thus, interganglionic interactions appear to play a relatively minor role in the steroid‐mediated metamorphic transformation of proleg motor neurons. © 1994 John Wiley & Sons, Inc.