bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regionalization and segmentation of the leech
Authors: Wedeen Cathy J. 
Published: January 2005

AbstractRegionalization and segmentation of the leech body plan have been examined by numerous approaches over the years. A wealth of knowledge has accumulated regarding the normally invariant cell lineages of the leech and the degree of developmental plasticity that is possible in each cell line in early development and in neurogenesis. Homologues of genes that control regionalization and segmentation in Drosophila have been cloned from the leech and the expression patterns reveal conserved features with those in Drosophila and other organisms. Possible developmental functions of the en‐class proteins in spatial and temporal modes of segment formation are discussed in light of leech and Drosophila development. Annelida and Arthropoda cell lineages of engrailed‐class gene expression are compared in leech blast cell clones and crustacean parasegments. In addition, future directions for molecular analysis of segmentation of the leech are summarized. © 1995 John Wiley & Sons, Inc.
Development of midbrain and anterior hindbrain ocular motoneurons in normal and Wnt‐1 knockout mice
Authors: Fritzsch B. , Nichols D. H. , Echelard Y. , McMahon A. P. 
Published: January 2005

AbstractThe effect of homozygotic Wnt‐1−/− mutations on the development of ocular motoneurons was examined with the lipophilic dye DiI and compared to control and phenotypic wild‐type mouse embryos. A piece of DiI‐soaked filter paper was inserted into the orbit, the midbrain, or rhombomere 5 of the hindbrain in six paraformaldehydefixed litters (10.5, 12.5, and 14.5 days postcoitum) containing Wnt‐1, Wnt+/−, and Wnt‐1+/+ individuals and three control litters. We labeled all ocular motoneurons retrogradely and all relevant nerves anterogradely in all control and phenotypic wild‐type animals. In all phenotypically identified Wnt‐1−/− mutants we could always label the abducens nerve and motoneurons and the optic fibers to the thalamus, but we were unable to lable oculomotor or trochlear nerves or motoneurons. In addition to Wnt‐1 knockout mutants, we also labeled mice from the WZT9B transgenic line carrying a lacZ reporter gene driven by the Wnt‐1 gene enhancer. In these embryos we tested for co‐localization of Wnt‐1 expression in biotinylated dextran amine‐labeled ocular motoneurons using a newly developed technique. In younger embryos we obtained evidence for co‐localization of the β‐galactosidase reaction product derived from lacZ gene activity in some retrogradely filled oculomotor motoneurons and adjacent to other oculomotor and the trochlear motoneurons. Acetylcholine esterase, a marker of early differentiating cholinergic neurons, showed a similar topology with respect to the lacZ reaction product. Thus, at least some future oculomotor motoneurons express Wnt‐1, whereas others and the trochlear motoneurons caudal to the ventral midbrain expression of Wnt‐1 may be exposed to the short range diffusion of the Wnt‐1 gene product. Thus, the Wnt‐1−/− mutation precludes formation or survival of midbrain and anterior hindbrain neurons, including oculomotor and trochlear motoneurons. © 1995 John Wiley & Sons, Inc.
Role of local nonspiking interneurons in the generation of rhythmic motor activity in the stick insect
Authors: Büschges Ansgar 
Published: January 2005

AbstractLocal nonspiking interneurons in the thoracic ganglia of insects are important premotor elements in posture control and locomotion. It was investigated whether these interneurons are involved in the central neuronal circuits generating the oscillatory motor output of the leg muscle system during rhythmic motor activity. Intracellular recordings from premotor nonspiking interneurons were made in the isolated and completely deafferented mesothoracic ganglion of the stick insect in preparations exhibiting rhythmic motor activity induced by the muscarinic agonist pilocarpine. All interneurons investigated provided synaptic drive to one or more motoneuron pools supplying the three proximal leg joints, that is, the thoraco‐coxal joint, the coxa‐trochanteral joint and the femur‐tibia joint. During rhythmicity in 83% (n=67) of the recorded interneurons, three different kinds of synaptic oscillations in membrane potential were observed: (1) Oscillations were closely correlated with the activity of motoneuron pools affected; (2) membrane potential oscillations reflected only certain aspects of motoneuronal rhythmicity; and (3) membrane potential oscillations were correlated mainly with the occurrence of spontaneous recurrent patterns (SRP) of activity in the motoneuron pools. In individual interneurons membrane potential oscillations were associated with phase‐dependent changes in the neuron's membrane conductance. Artificial changes in the interneurons' membrane potential strongly influenced motor activity. Injecting current pulses into individual interneurons caused a reset of rhythmicity in motoneurons. Furthermore, current injection into interneurons influenced shape and probability of occurrence for SRPs. Among others, identified nonspiking interneurons that are involved in posture control of leg joints were found to exhibit the above properties. From these results, the following conclusions on the role of nonspiking interneurons in the generation of rhythmic motor activity, and thus potentially also during locomotion, emerge: (1) During rhythmic motor activity most nonspiking interneurons receive strong synaptic drive from central rhythm‐generating networks; and (2) individual nonspiking interneurons some of which underlie sensory‐motor pathways in posture control, are elements of central neuronal networks that generate alternating activity in antagonistic leg motoneuron pools. © 1995 John Wiley & Sons, Inc.
Differential regulation of motor neuron survival and choline acetyltransferase expression following axotomy
Authors: Kou Shi‐Ying , Chiu Arlene Y. , Patterson Paul H. 
Published: January 2005

AbstractAlthough it is well known that motor neuron survival following axotomy is enhanced with maturation, the ability of surviving neurons to express the cholinergic enzyme choline acetyltransferase (ChAT) following axotomy has not been closely examined. Moreover, the utility of the facial nucleus in studies of motoneuron response to injury and to trophic factors, coupled with the increasing importance of the mouse in gene targeting, compelled us to investigate the age dependence of neuronal survival and ChAT expression in the mouse facial nucleus following axotomy. We cut the facial nerve at postnatal day (P)4, 7, 14, 21, and 28 or in the adult and used Nissl staining and ChAT immunocytochemistry to quantitate survival and ChAT expression, respectively, following 1, 2, or 3 weeks' survival at each age. We confirm in this model that the rate and extent of motor neuron death following axotomy is reduced with increasing maturity. The surviving neurons maintain a high ChAT content through P21; however, axotomy from P28 through adulthood results in a striking reduction in ChAT immunoreactivity. That is, although axotomy at P21 results in 61% motor neuron survival, with virtually all of the surviving neurons being ChAT positive, axotomy in the adult results in 72% survival but only 9% of the neurons are ChAT positive. Thus, surviving motor neurons in the adult animals are only weakly cholinergic. These results indicate that a change in the regulation of ChAT expression occurs following P21 so that cell survival and enzyme levels are uncoupled. We suggest that the putative factor or factors that enhances motor neuron survival in maturity is not capable of maintaining ChAT expression. © 1995 John Wiley & Sons, Inc.
Evidence for glutamate‐mediated activation of hippocampal neurons by glial calcium waves
Authors: Hassinger Tim D. , Atkinson Paul B. , Strecker George J. , Whalen L. Ray , Dudek F. Edward , Kossel Albrecht H. , Kater S. B. 
Published: January 2005

AbstractCommunication from astrocytes to neurons has recently been reported by two laboratories, but different mechanisms were thought to underlie glial calcium wave activation of associated neurons. Neuronal calcium elevation by glia observed in the present report is similar to that reported previously, where an increase in neuronal calcium was demonstrated in response to glial stimulation. In the present study hippocampal neurons plated on a confluent glial monolayer displayed a transient increase in intracellular calcium following a short delay after the passage of a wave of increased calcium in underlying glia. Activated cells displayed action potentials in response to glial waves and showed antineurofilament immunoreactivity. Finally, the N‐methyl‐D‐aspartate glutamate receptor antagonist DL‐2‐amino‐5‐phosphonovaleric acid and the non‐NMDA glutamate receptor antagonist 6,7‐dinitroquinoxaline‐2,3‐dione significantly reduced the responsiveness of neurons to glial calcium waves. Our results indicate that hippocampal neurons growing on hippocampal or cortical astrocytes respond to glial calcium waves with elevations in calcium and increased electrical activity. Furthermore, we show that in most cases this communication appears to be mediated by ionotropic glutamate receptor channels. © 1995 John Wiley & Sons, Inc.
Neurotrophin‐4/5, brain‐derived neurotrophic factor, and neurotrophin‐3 promote survival of cultured vestibular ganglion neurons and protect them against neurotoxicity of ototoxins
Authors: Lisa Zheng J. , Stewart Randall R. , Gao Wei‐Qiang 
Published: January 2005

AbstractThe ability of neurotrophin‐4/5 (NT‐4/5), brain‐derived neurotrophic factor (BDNF), neurotrophin‐3 (NT‐3), and nerve growth factor (NGF) to promote survival of postnatal rat vestibular ganglion neurons (VGNs) was examined in dissociated cell cultures. Of the four neurotrophins, NT‐4/5 and BDNF were equally effective but more potent than NT‐3 in promoting the survival of VGNs. In contrast, NGF showed no detectable effects. As expected, TrkB‐IgG (a fusion protein of extracellular domain of TrkB and Fc domain of human immunoglobulin G) specifically inhibited the survival‐promoting effects by NT‐4/5 or BDNF and TrkC‐IgG fusion protein completely blocked that of NT‐3. Immunohistochemistry with TrkB, TrkA, and p75 antisera revealed that VGNs made TrkB and p75 proteins, but not TrkA protein. Ototoxic therapeutic drugs such as cisplatin and gentamicin often induce degeneration of hair cells and ganglion neurons in both auditory and vestibular systems that leads to impairment of hearing and balance. When cisplatin and gentamicin were added to the dissociated VGN culture in which the hair cells were absent, additional cell death of VGNs was induced, suggesting that the two ototoxins may have a direct neurotoxic effect on ganglion neurons in addition to their known toxicity on hair cells. However, if the cultures were co‐treated with neurotrophins, NT‐4/5, BDNF, and NT‐3, but not NGF, prevented or reduced the neurotoxicity of the two ototoxins. Thus, the three neurotrophins are survival factors for VGNs and are implicated in the therapeutic prevention of VGN loss caused by injury and ototoxins. © 1995 John Wiley & Sons, Inc.
Tenascin‐C mRNA is expressed in cranial neural crest cells, in some placodal derivatives, and in discrete domains of the embryonic zebrafish brain
Authors: Tongiorgi Enrico , Bernhardt Robert R. , Zinn Kai , Schachner Melitta 
Published: January 2005

AbstractA partial zebrafish tenascin‐C cDNA clone was isolated from an embryonic zebrafish cDNA library on the basis of homology to mouse tenascin‐C. The expression pattern in the head of embryonic zebrafish was analyzed by in situ hybridization. Tenascin‐C mRNA was detected in neural crest cells during the period of their migration and differentiation. Expression also occurred in differentiating placodal tissues and in mesodermal cells. In the developing brain, tenascin‐C mRNA was expressed in specific domains. In the hindbrain the pattern of the domains was dynamic. At 18 to 22 h postfertilization, expression was widespread in rhombomeres 3, 5, and 6, confined to periventricular cells in rhombomere 2, and not detectable in rhombomere 4. At 32 h postfertilization, tenascin‐C was expressed at the rhombomere boundaries. In contrast to the hindbrain, the pattern in the forebrain and midbrain did not show any major changes between 22 and 32 h postfertilization. Domains expressing tenascin‐C alternated with regions devoid of it. The most anterior domain of expression was observed at the telencephalic‐diencephalic border, surrounding the optic recess. A second domain, at the border between the diencephalon and the midbrain, and a third domain, in the caudal midbrain tegmentum, appeared restricted to the basal plate. Additionally, expression of tenascin‐C mRNA was detected in the hypothalamus and in the developing epiphysis. These expression patterns suggest that tenascin‐C may play a role in neural crest cell migration and during the differentiation of neural crest, placodal, and mesodermal derivatives. In the developing brain, tenascin‐C may be involved in the consolidation of different regional identities. © 1995 John Wiley & Sons, Inc.
Comprehensive analysis of the extracellular proteins from Xanthomonas campestris pv. campestris B100
Authors: Watt Steven Alexander , Wilke Andreas , Patschkowski Thomas , Niehaus Karsten 
Published: January 2005

AbstractThe extracellular proteome of Xanthomonas campestris pv. campestris (Xcc) cultivated in minimal medium was isolated from the cell‐free culture supernatant and separated by two‐dimensional gel electrophoresis. This technique resolved 97 clearly visible protein spots, which were excised, digested with trypsin and identified on the basis of their peptide mass fingerprints generated by matrix assisted laser desorption/ionisation‐time of flight‐mass spectrometry. Using this approach 87 different proteins could be distinguished. The Signal P software predicted putative signal peptides for 53% of the extracellular proteins. These proteins are probably transported over the inner membrane and are localized in the periplasm, the outer membrane or secreted into the extracellular space. Among the secreted proteins are 11 degradative enzymes, which are involved in pathogenesis of Xcc. The proteins without obvious secretion signals are known to serve functions in the cytosol. How the cytosolic proteins are delivered to the extracellular space remains unclear.
Kinetics and mechanism of reaction of benzyl bromide with copper in dimethylacetamide
Authors: Egorov Anatoly M. , Matyukhova Svetlana A. , Anisimov Alexander V. 
Published: January 2005

AbstractThe reaction of copper with various benzyl bromides in dimethylacetamide was studied. In the absence of atmospheric oxygen, oxidative dissolution of copper occurred by the mechanism of single electron transfer with the formation of 1,2‐diphenylethane and copper(I) complexes. The kinetic and thermodynamic parameters of the reaction have been obtained and the reaction mechanism is discussed. Copyright © 2004 John Wiley & Sons, Ltd.
Changes in neurotransmitter uptake in the spinal cord following peripheral nerve injury
Authors: Somps Christopher J. , Boyajian Christine L. , Luttges Marvin W. 
Published: January 2005

AbstractChanges in neurotransmitter systems of the spinal cord were studied in response to peripheral nerve injury. The uptake and compartmentalization of radiolabeled spinal cord neurotransmitters and transmitter precursors were examined as a function of time following unilateral sciatic nerve crush in adult mice. Accumulation of transmitter was measured within synaptosomally enriched fractions prepared using combinations of differential and density gradient centrifugations. The amount of transmitter substance recovered from these fractions was strongly depedent upon the amount of time following nerve injury and on the specific transmitter or precursor being examined (GABA, glutamate, glycine, and choline chloride). However, for each of these substances, uptake values returned to control levels within nine to twelve days after nerve crush. Localization of GABA changes postcrush revealed reciprocal differences between ipsilateral and contralateral sides of the spinal cord, as well as differences between segmental levels. Altered GABA uptake may reflect changes in the postcrush microchemical environment present during tissue processing, but may also be related to direct changes in the synaptic binding, transport, and compartmentalization of transmitter substance. The time course, magnitude, and direction of these neurochemical changes follow those observed neurophysiologically, and may thus underlie injury‐induced short‐term (days) alterations reported in primary afferent depolarizations, cross cord responses, and other spinal mechanisms.
Cerebellin and related postsynaptic peptides in the brain of normal and neurodevelopmentally mutant vertebrates
Authors: Morgan J. I. , Slemmon J. R. , Danho W. , Hempstead J. , Berrebi A. S. , Mugnaini E. 
Published: January 2005

AbstractThe rat cerebellum was previously shown to contain two polypeptides, a hexadecapeptide termed cerebellin and an apparent metabolite des‐Ser1‐cerebellin. The cerebellins have a high degree of sequence homology with residues 625–641 of the polyimmunoglobulin (polyIg)‐receptor adjacent to its membrane‐spanning domain. Since the cerebellins are localized in Purkinje cells and enriched in synaptosomes, this might indicate that cerebellin is a specific proteolytic cleavage fragment of a synaptic protein involved in the transcytosis of an unknown ligand. Using a specific cerebellin radioimmunoassay described here combined with high‐performance liquid chromatography, cerebellin immunoreactivity could be demonstrated in the cerebella of all vertebrates examined from man to chicken. Cerebellin immunoreactivity is localized to Purkinje cells in the rat, mouse, and chicken. Furthermore, cerebellin expression is under developmental regulation in both the chicken and mouse. In addition, neurodevelopmental mutations of mice that eliminate granule cells cause a large deficit in cerebellin levels, suggesting some form of transneuronal regulation.
Reduction of postjunctional fold density and depth in dystrophic mice
Authors: Tremblay Jacques P. , Grégoire Laurent , Sasseville Rachelle , Guay Gabrielle , Belhumeur Céline 
Published: January 2005

AbstractA total of 769 neuromuscular junction profiles (on 221 muscle fibers) from 21 normal (C57BL/6J +/+), 6 heterozygous (C57BL/6J dy2J/+) and 22 homozygous dystrophic (C57BL/6J dy2 J/dy2J) gastrocnemius were photographed in electron microscopy. The fast and slow twitch muscle fibers were differentiated by the width of the Z lines. The number of secondary postjunctional folds per unit length of synaptic cleft was lower in dystrophic than in normal animals. Intermediate values were obtained in heterozygous animals. The length of the postsynaptic membrane was measured and normalized by dividing it by the length of the cross‐section through the synaptic cleft. This normalized length of postjunctional membrane was significantly reduced by 45% in dystrophic animals relative to normals animals and by 41% relative to heterozygous animals. The depth of the secondary folds was also significantly reduced in dystrophic animals relative to normal animals in both fast and slow twitch fibers. These morphometric changes of the postjunctional membrane were observed on NMJs whose nerve terminals were not significantly modified by the dystrophic process and were sometimes observed on apparently normal muscle fibers.
Control of feeding and sexual behaviors by neuropeptide Y: Physiological implications
Authors: Kalra Satya P. , Clark John T. , Sahu Abhiram , Dube Michael G. , Kalra Pushpa S. 
Published: January 2005

AbstractRecent evidence suggests that a variety of hypothalamic neuropeptides may mediate interneuronal communication to coordinate diverse neuroendocrine and behavioral functions. In this work, we describe the effects of neuropeptide Y (NPY) on feeding and sexual behaviors. We observed that central administration of bolus NPY stimulated a robust, dose‐related feeding response in satiated male and female rats. Continuous NPY receptor activation also evoked dose‐related, intermittent feeding in a manner normally observed during nocturnal feeding. It appears that the paraventricular nucleus in the hypothalamus may be the primary site of NPY action because the anticipated reciprocal changes in NPY concentrations, in response to food deprivation followed by ad libitum food intake, occurred only in this site. Additional findings revealed that NPY‐induced feeding may follow either substantial reduction or complete restraint of an inhibitory influence on feeding mediated by α2‐adrenoreceptor systems in satiated rats. Further, NPY was found to suppress male and female sexual behaviors. The suppressive effects on sexual behavior were apparent prior to or at the time of the onset of feeding after NPY administration. These observations may provide a neurochemical basis for clinical and animal studies on disorders of feeding associated with diminished reproductive functions.
Norepinephrine throughout the spinal cord of the cat: I. Normal quantitative laminar and segmental distribution
Authors: Massari V. John , Park Chan H. , Suyderhoud Johan P. , Tizabi Yousef 
Published: January 2005

AbstractNorepinephrine (NE) concentrations were measured by radioenzymatic assay in microdissected individual laminae of each segment of the cat spinal cord. Norepinephrine was detected in all areas of the spinal gray matter and showed more than a 7‐fold difference in concentration between the laminae with the highest and lowest NE. The cervical, thoracic, and lumbosacral spinal regions showed significant interlaminar differences in NE. Intersegmental changes in NE were seen within single laminae of the thoracic and lumbosacral spinal cord, but not in the cervical spinal cord. A significant rostral to caudal, increasing regional gradient of NE was observed from the cervical to lumbosacral spinal cord in laminae I‐III, V, VI, VII, and IX. In the intermediolateral cell column (IML), epinephrine concentrations were 2 to 5% of NE. Neither neurotransmitter showed a significant intersegmental variation in the IML. These data should prove useful in further defining the precise role of NE in specific regions of the spinal cord that mediate sensory, motor, autonomic, or propriospinal functions.
α‐Melanocyte‐stimulating hormone structure‐activity studies: Comparative analysis of melanotropic and CNS bioactivities
Authors: Sawyer Tomi K. , Hadley Mac E. , Hruby Victor J. , de Lauro Castrucci Ana Maria , Staples Douglas J. , Farah John , L. O'donohue Thomas 
Published: January 2005

AbstractThe structure‐activity relationships in vitro of α‐MSH (α‐melanocyte‐stimulating hormone, α‐melanotropin) analogs as determined on normal and transformed (melanoma cell) melanocyte bioassays are summarized. Specifically, the characterization of potent and metabolically stable melanotropic agonist analogs and a newly discovered antagonist of α‐MSH are highlighted. Comparison of these data versus the known structure‐activity relationships of α‐MSH related to CNS bioactivities suggests the existence of nonclassical α‐MSH receptor‐mediated pathways or, perhaps, a yet undefined endogenous neuropeptidergic pathway(s) having different selectivities for α‐MSH analogs. In summary, several of the α‐MSH analogs reported here may be useful molecular probes in future strategies aimed at the identification and systematic characterization of both peripheral and central α‐MSH receptors.