bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dividing neuron precursors express neuron‐specific tubulin
Authors: Memberg Stacey P. , Hall Alison K. 
Published: January 2005

AbstractNeuronal differentiation involves specific molecular and morphological changes in precursors and results in mature, postmitotic neurons. The expression of neuron‐specific β tubulin, as detected by the monoclonal antibody TuJ1, begins during the period of neurogenesis. Indeed, TuJ1 expression precedes that of the 160 kD neurofilament protein in both the central and peripheral nervous systems. In the embryonic rat spinal cord, bipolar cells and some mitotic cells in the ventricular zone were TuJ1 immunoreactive (IR). Sensory ganglia also contained cells with TuJ1‐IR mitotic spindles in situ. In embryonic rat sensory and sympathetic ganglion cell cultures pulsed with the thymidine analog bromodeoxyuridine (BrdU), TuJ1 label was detected in the spindle of mitotic cells and in the midbody of cells joined at cytokinesis, indicating that neuron‐specific tubulin expression was initiated during or before the final mitosis of neuronal progenitors. Dorsal root ganglion cultures included TuJ1‐IR cells with several shapes that may reflect morphological transitions, from flattened stellate neural crest‐like cells to differentiated bipolar neurons. Indeed, the presence of flattened TuJ1‐IR cells was correlated with neurogenesis. Some sympathetic neuron precursors possessed long TuJ1‐IR neurites, as well as TuJ1‐IR spindle microtubules and BrdU‐labeled chromosomes, indicating that these precursors can possess long processes during metaphase. These results support the hypothesis that neuron‐specific tubulin expression represents an early molecular event in neuronal differentiation exhibited by a wide range of neuronal precursors. The cessation of proliferation can occur at different points during neuronal differentiation, as TuJ1‐IR was detected in cells undergoing mitosis. Future studies directed toward understanding the molecules that initiate neuron‐specific tubulin expression may lead to the factors that control the initial phases of neuronal differentiation. © 1995 John Wiley & Sons, Inc.
Initial sex differences in neuron growth and survival within an avian song nucleus develop in the absence of afferent input
Authors: Burek Michael. J. , Nordeen K. W. , Nordeen E. J. 
Published: January 2005

AbstractOnly male zebra finches (Poephila guttata) sing, and nuclei implicated in song behavior exhibit marked sex differences in neuron number. In the robust nucleus of the anterior neostriatum (RA), these sex differences develop because more neurons die in young females than in males. However, it is not known whether the sexually dimorphic survival of RA neurons is a primary event in sexual differentiation or a secondary response to sex differences in the number of cells interacting trophically with RA neurons. In particular, since sexual differentiation of the RA parallels the development of dimorphisms in the numbers of neurons providing afferent input from the lateral magnocellular nucleus of the anterior neostriatum (lMAN) and the high vocal center (HVC), it has been hypothesized that sex differences in the size of these afferent populations trigger differential RA neuron survival and growth. To test this hypothesis, we lesioned either the lMAN or both the lMAN and HVC unilaterally in 12‐day‐old male and female zebra finches. Subsequently, RA cell death and RA neuron number and size were measured. Unilateral lMAN lesions increased cell death and decreased neuron number and size within the ipsilateral RA of both sexes. However, even in the lMAN‐lesioned hemisphere, these effects were less pronounced in males than in females, so that by day 25 the volume, number, and size of neurons were sexually dimorphic in both the contralateral and ipsilateral RA. Similarly, the absence of both lMAN and HVC afferents did not prevent the emergence of sex differences in the number and size of RA neurons by 25 day posthatching. We conclude that these sex differences within the RA are not a secondary response to dimorphisms in the numbers of lMAN or HVC neurons providing afferent input. © 1995 John Wiley & Sons, Inc.
Astroglia demonstrate regional differences in their ability to maintain primary dendritic outgrowth from mouse cortical neurons in vitro
Authors: Le Roux Peter D. , Reh Thomas A. 
Published: January 2005

AbstractTo determine whether glia from different regions of the central nervous system (CNS) initiate or maintain primary dendritic growth, embryonic day 18 mouse cortical neurons were co‐cultured with rat (postnatal day 4) astroglial cells derived from retina, spinal cord, mesencephalon, striatum, olfactory bulb, retina, and cortex. Axon and dendrite outgrowth from isolated neurons was quantified using morphological and immunohistochemical techniques at 18 h and 1, 3, and 5 days in vitro. Neurons initially extend the same number of neurites, regardless of the source of glial monolayer; however, glial cells differ in their ability to maintain primary dendrites. Homotypic cortical astrocytes maintain the greatest number of primary dendrites. Glia derived from the olfactory bulb and retina maintained intermediate numbers of dendrites, whereas only a small number of primary dendrites were maintained by glia derived from striatum, spinal cord, or mesencephalon. Longer axons were initially observed from neurons grown on glia that did not maintain dendrite number. Axonal length, however, was similar on the various monolayers after 5 days in vitro. Neurons that were grown in media conditioned by either mesencephalic or cortical glia for the first 24 h followed by culture media from glia of the alternate source for 4 days in vitro confirmed that glia maintained, rather than initiated, the outgrowth of the primary dendritic arbor. These results indicate that glial cells derived from various CNS regions differ in their ability to maintain the primary dendritic arbor from mouse cortical neurons in vitro. © 1995 John Wiley & Sons, Inc.
Formation and specification of neurons during the development of the leech central nervous system
Authors: Shankland Marty 
Published: January 2005

AbstractIn the leech embryo, neurogenesis takes place within the context of a stereotyped cell lineage. The prospective germ layers are formed during the early cleavage divisions by the reorganization and segregation of circumscribed domains within the cytoplasm of the fertilized egg. The majority of central neurons arise from the ectoderm, and central neuroblasts are distributed throughout both the length and width of each ectodermal hemisegment. Much of the segmental ganglion arises from medial neuroblasts, but there are also lateral ectodermal neuroblasts and mesodermal neuroblasts that migrate into the nascent ganglion from peripheral sites of origin. Some of these migratory cells are committed to neurogenesis prior to reaching their central destination. In addition, the leech embryo exhibits a secondary phase of neurogenesis that is restricted to the two sex segment ganglia. Secondary neurogenesis requires that a mitogenic or trophic signal be conveyed from the peripherally located male sex organ to a particular set of centrally located neuroblasts, apparently via already differentiated central neurons that innervate the sex organ. The differential specification of neuronal phenotypes within the leech central nervous system occurs in multiple steps. Some aspects of a neuron's identity are already specified at the time of its terminal cell division and would seem to involve the lineal inheritance of developmental commitments made by one of the neuron's progenitors. This lineage‐based identity can then be modified by interactions between the postmitotic neuron and other neurons or non‐neuronal target cells encountered during its terminal differentiation. © 1995 John Wiley & Sons, Inc.
Neuronal control of leech swimming
Authors: Brodfuehrer Peter D. , Debski Elizabeth A. , O'Gara Bruce A. , Friesen W. Otto 
Published: January 2005

AbstractLeech swimming is produced by the antiphasic contractions of dorsal and ventral longitudinal muscles that travel rearward along the animal and propel it forward. Research over the past three decades has focused on identifying the underlying neuronal circuit and mechanisms that produce and control this coordinated movement pattern. Investigations have also tested whether leech swimming is modifiable, both by experience and by neuromodulators. One outcome has been the identification of several functional classes of neurons associated with swimming. Systematic analysis of the interactions between these neurons had led to the elucidation of a neuronal circuit that adequately accounts for the generation of the swim motor program cord. The swim motor program appears to be produced by a chain of coupled segmental oscillators whose intrinsic properties and intersegmental connections ensure the coordinated expression of swimming along the nerve cord. In addition, neurons identified in the head ganglion comprise two parallel, but opposite‐acting, systems that control the initiation of swimming in response to sensory input. Also, the pathway by which body wall stimulation initiates swimming show a simple form of learning, that is habituation. Repeatedly stroking the leech body wall decreases both the probability of initiating swimming and the length of elicited swim episodes. Finally, the biogenic amine serotonin, which is found in the nerve cord, affects leech swimming in a number of ways. Serotonin's modulation of swimming is due, in part, to its effect on the membrane properties of swim‐initiating interneurons and several swim motor neurons. © 1995 John Wiley & Sons, Inc.
Inhibition of formation of filopodia after axotomy by inhibitors of protein tyrosine kinases
Authors: Goldberg Daniel J. , Wu Da‐Yu 
Published: January 2005

AbstractThe activity of motile protrusions of the growth cone—filopodia, veils, and lamellipodia—is essential for directed growth of a neuronal process. The regulation of the formation of these protrusions is not well understood. Numerous filopodia and veils or lamellipodia form within minutes of transection of an Aplysia axon in culture, as the initial components of growth cones of regenerating neurites. Axotomy, therefore, provides a robust and reliable protocol for analyzing the formation of these protrusions. We evaluated the involvement of protein phosphorylation in the regulation of protrusive activity. Of the inhibitors of protein kinases assayed, only the inhibitors of protein tyrosine kinases—genistein, lavendustin A, herbimycin A, and erbstatin analogue—suppressed the formation of protrusions, as assessed by high magnification video microscopy. These drugs did not work by preventing resealing of the axon, as evident from visual inspection and by the unimpaired effectiveness of genistein or lavendustin in preventing formation of filopodia when applied after resealing. Inhibition of protein tyrosine kinases not only prevented the formation of actinbased protrusions, but also caused deterioration of the actin network underlying the protrusive area of preexisting growth cones. Consistent with an involvement of protein tyrosine phosphorylation in the generation of protrusive structures, immunocytochemistry revealed that aggregates of phosphotyrosine appeared at the margins of the axon, from which protrusions emerge shortly after axotomy. These results suggest a role for protein tyrosine phosphorylation in the formation and maintenance of actin‐based protrusive structures. © 1995 John Wiley & Sons, Inc.
Ca2+ responses to acetylcholine and adenosine triphosphate in the otocyst of chick embryo
Authors: Nakaoka Yoshikazu , Yamashita Masayuki 
Published: January 2005

AbstractThe action of acetylcholine and adenosine triphosphate (ATP) on cytoplasmic Ca2+ concentration ([Ca2+]i) was studied in the otocyst epithelium of embryonic day 3 chicks with Ca2+‐sensitive fluorescence measurements. Increases in [Ca2+]i were evoked by the bath application of acetylcholine (1 μM or higher). The rise in [Ca2+]i was due to the release of Ca2+ from intracellular Ca2+ stores, since the Ca2+ response occurred even in a Ca2+‐free medium. The Ca2+ response to acetylcholine was mediated by muscarinic receptors. Atropine of 1 μM abolisehd the response to 10 μM acetylcholine; muscarine and carbamylcholine (100 μM each) evoked Ca2+ rises. Increases in [Ca2+]i were also evoked by the bath application of ATP (10 μM or higher). The Ca2+ rise by ATP was evoked even in a Ca2+‐free medium. Adenosine (500 μM) did not cause any Ca2+ response. Suramin and reactive blue 2 (200 μM each) completely blocked the Ca2+ response to 500μM ATP. Uridine triphosphate (500 μM) caused comparable Ca2+ responses with those to 500 μM ATP. These results suggested the involvement of P2U purinoceptors. The potentiation of Ca2+ rise was observed when acetylcholine and ATP were co‐applied at submaximal concentrations (10 μM and 100 μM, respectively). We conclude that undifferentiated cells in the otocyst epithelium have CaCa2+ mobilizing systems activated by acetylcholine and ATP. © 1995 John Wiley & Sons, Inc.
Overlapping and differential expression of BIG‐2, BIG‐1, TAG‐1, and F3: Four members of an axon‐associated cell adhesion molecule subgroup of the immunoglobulin superfamily
Authors: Yoshihara Yoshihiro , Kawasaki Miwa , Tamada Atsushi , Nagata Shigekazu , Kagamiyama Hiroyuki , Mori Kensaku 
Published: January 2005

AbstractAxon‐associated cell adhesion molecules (AxCAMs) play crucial roles in the formation, maintenance, and plasticity of functional neuronal networks. We report here a molecular cloning of a novel AxCAM, BIG‐2. BIG‐2 is a member of TAG‐1/F3 subgroup of the immunoglobulin (Ig) superfamily, with six Ig‐like domains, four fibronectin type III‐like repeats, and a glycosyl phosphatidylinositol‐anchoring domain. Recombinant BIG‐2 protein had a neurite outgrowth‐promoting activity when used as a substrate for neurons in vitro. To survey the spatial expression pattern of BIG‐2 in comparison with other TAG‐1/F3 subgroup members, an in situ hybridization analysis was performed in adult and developing rat brain sections with riboprobes specific for BIG‐2, BIG‐1, TAG‐1, and F3. The four AxCAM transcripts displayed cell type‐specific expression patterns with overlapping and distinct profiles. In adult hippocampus, for example, we observed BIG‐1 mRNA specifically in granule cells of the dentate gyrus, BIG‐2 mRNA highly in the CA1 pyramidal cells, TAG‐1 mRNA predominantly in the CA3 pyramidal cells, and F3 mRNA in neurons in all of these fields. These results suggest that BIG‐2, BIG‐1, TAG‐1, and F3 may play important roles in the formation and maintenance of specific neuronal networks in the brain. © 1995 John Wiley & Sons, Inc.
20‐hydroxyecdysone stimulates proliferation of glial cells in the developing brain of the moth Manduca sexta
Authors: Kirschenbaum Sheila R. , Higgins Mark R. , Tveten Michael , Tolbert Leslie P. 
Published: January 2005

AbstractThe steroid hormone 20‐hydroxyecdysone (20‐HE) controls diverse aspects of neuronal differentiation during metamorphosis in the hawkmoth Manduca sexta. In the present study we have examined the effect of 20‐HE on glial cells of the brain during the metamorphic period. The antennal (olfactory) lobe of Manduca provides an ideal system in which to study effects of hormones on glial cells, since three known classes of glial cells participate in its development, and at least one type is critically important for establishment of normal neuronal morphology. These glial cells, associated with the neuropil, form boundaries for developing olfactory glomeruli as a result of proliferation and migration. We determined whether glial cells proliferate in response to 20‐HE by injecting a pulse of 20‐HE into the hemolymph at different stages of development and monitoring proliferation of all three types of glial cells. Hormone injections at the beginning and end of metamorphic development, when hormone titers are normally low, did not stimulate proliferation of neuropil‐associated glial cells. Injections during the period when hormone titers are normally rising produced significant increases in their proliferation. Injections when hormone titers are normally high were ineffective at enhancing their proliferation. One other class of glial cells, the perineurial cells, also proliferate in response to 20‐HE. Thus, glial proliferation in the brain is under the control of steroid hormones during metamorphic development. © 1995 John Wiley & Sons, Inc.
Profiling of abundant proteins associated with dichlorodiphenyltrichloroethane resistance in Drosophila melanogaster
Authors: Pedra Joao H. F. , Festucci‐Buselli Reginaldo A. , Sun Weilin , Muir William M. , Scharf Michael E. , Pittendrigh Barry R. 
Published: January 2005

AbstractDichlorodiphenyltrichloroethane (DDT) metabolism‐based resistance in Drosophila melanogaster is a complex metabolic system associated with the transcription of detoxification related genes, ion transport, lipid and sugar metabolism pathways. However, little is known about the differences regarding the proteome of field‐ and laboratory‐selected resistant Drosophila genotypes. We investigated the impact of DDT resistance in the abundant proteome of field‐ and laboratory‐ selected resistant Drosophila using a two‐dimensional gel electrophoresis DDT reference map. Proteomic profiling was performed in two DDT susceptible genotypes (Canton‐S and 91‐C) and three DDT resistant lines (Rst(2)DDT91‐R, Rst(2)DDTWisconsin and Rst(2)DDTHikone‐R). Protein spots were stained with Coomassie blue and compared using PDQuest software. Selected protein spots were cut out and analyzed using matrix assisted laser desorption‐time of flight mass spectrometry. Querying the NCBInr. 10.21.2003 database with mass spectrometric data yielded the identity of 21 differentially translated proteins in Rst(2)DDT91‐R, Rst(2)DDTWisconsin and Canton‐S representing proteins putatively involved in biochemical pathways such as glycolysis and gluconeogenesis, the pentose phosphate pathway, the Krebs cycle and fatty acid oxidation. We hypothesize that both strategies are aimed to use of the pentose phosphate pathway to increase glucose utilization while Rst(2)DDT91‐R relies primarily on glycolysis to produce reduced NADP and increase DDT detoxification. DDT exposure in Canton‐S induced six proteins, while four proteins were repressed in Rst(2)DDTHikone‐R. Our data suggest that insecticide resistance appears to impact different metabolic pathways in Drosophila genotypes selected with the same pesticide (DDT).
The membrane proteome of Halobacterium salinarum
Authors: Klein Christian , Garcia‐Rizo Carolina , Bisle Birgit , Scheffer Beatrix , Zischka Hans , Pfeiffer Friedhelm , Siedler Frank , Oesterhelt Dieter 
Published: January 2005

AbstractThe identification of 114 integral membrane proteins from Halobacterium salinarum was achieved using liquid chromatography/tandem mass spectrometric (LC/MS/MS) techniques, representing 20% of the predicted alpha‐helical transmembrane proteins of the genome. For this experiment, a membrane preparation with only minor contamination by soluble proteins was prepared. From this membrane preparation a number of peripheral membrane proteins were identified by the classical two dimensional gel electrophoresis (2‐DE) approach, but identification of integral membrane proteins largely failed with only a very few being identified. By use of a fluorescently labeled membrane preparation, we document that this is caused by an irreversible precipitation of the membrane proteins upon isoelectric focusing (IEF). Attempts to overcome this problem by using alternative IEF methods and IEF strip solubilisation techniques were not successful, and we conclude that the classical 2‐DE approach is not suited for the identification of integral membrane proteins. Computational analysis showed that the identification of integral membrane proteins is further complicated by the generation of tryptic peptides, which are unfavorable for matrix assisted laser desorption/ionization time of flight mass spectrometric peptide mass fingerprint analysis. Together with the result from the analysis of the cytosolic proteome (see preceding paper), we could identify 34% (943) of all gene products in H. salinarum which can be theoretically expressed. This is a cautious estimate as very stringent criteria were applied for identification. These results are available under www.halolex.mpg.de.
Modification of nicotinic ganglionic transmission by muscarinic slow postsynaptic potentials in the in vitro rabbit superior cervical ganglion
Authors: Yarosh C. A. , Acosta C. G. , Ashe John H. 
Published: January 2005

AbstractThe influence of slow muscarinic postsynaptic potentials, i.e., the s‐IPSP and s‐EPSP, on synaptic transmission mediated through nicotinic receptors was studied in the superior cervical ganglion of the rabbit. Postganglionic spikes and synaptic potentials were elicited by delivery of conditioning and test stimulus pulses to afferent fibers. When paired stimulus volleys were separated by brief intervals (20–100 msec) or long intervals (1,000–8,000 msec), the population spike elicited by the test stimulus was larger in amplitude than that elicited by the conditioning volley. When paired stimulus volleys were separated by 250–500 msec, the amplitude of the population spike elicited by the test volley was smaller than that elicited by the conditioning stimulus. Gallamine, which selectively blocks the s‐IPSP, reduced the suppression of the test spike which occurred when stimulus IPIs ranged between 250–500 msec. Pirenzepine, which selectively blocks the s‐EPSP, reduced the late facilitation of test postganglionic spikes which occurred with stimulus IPIs greater than 1,000 msec. The non‐selective muscarinic antagonist QNB, produced changes in postganglionic spike amplitude that were similar to the combined effects of gallamine and pirenzepine. The evidence indicates that the s‐IPSP and s‐EPSP modified the excitability state of the ganglionic neurons and subsequent synaptic transmission that was mediated through nicotinic receptors.
Biochemical and behavioral effects of sigma and PCP ligands
Authors: Contreras Patricia C. , Contreras Margarita L. , L. O'donohue Thomas , Lair Cecelia C. 
Published: January 2005

AbstractThe purpose of this study was to examine the binding and behavioral effects mediated by PCP and sigma receptors in the rat. From the radioreceptor assays, it was possible to characterize two binding sites that interact with PCP and sigma ligands. The two sites, a PCP and sigma receptor, could be differentiated based on drug selectivity and potency. In the behavioral assays, MK‐801, which bound preferentially to the PCP receptor, and 1,3‐di‐O‐tolylguanidine, which bound preferentially to the sigma receptor, induced sniffing, rearing, circling, backpedaling, and weaving behavior. These results indicate that there are distinct PCP and sigma receptors that are both involved in mediating stereotyped behavior and ataxia in the rat.
Nuclear protein kinase substrates in AtT‐20 cells: Translocation of a 14 kDa phosphoprotein
Authors: Bishop John F. , Chronwall Bibie M. , Farah John M. , Gehlert Donald R. 
Published: January 2005

AbstractIn this work we characterize some acidic nuclear substrates of protein kinase C (PKC) and cyclic AMP‐dependent protein kinase (PKA), using intact anterior pituitary corticotrophic tumor cells (AtT‐20/D16‐16). It was found that, as in the cytosolic fraction, substrates for both PKC and PKA exist in the nucleus and that changes in the phosphorylation states of a few of these phosphoproteins are mediated by both kinases. One of the phosphoproteins examined, a 14 kDa phosphoprotein (pp14) described previously, exhibited a phorbol‐ester induced translocation from nucleus to cytosol in pulsechase experiments utilizing 35S‐methionine labeling. These results suggest that pp14 may be involved in signal transduction in AtT‐20 cells. Although its identity remains to be determined, a 14 kDa DNA‐binding protein was also seen in nuclear extracts of AtT‐20 cells.