bluuebunny/crossref_metadata_2025 huggingface dataset:
Examples of Lie and Balinsky-Novikov algebras related to Hamiltonian operators
Authors: Artemovych Orest D. , Prykarpatski Anatolij K. , Blackmore Denis L.
Published: April 2018

We study algebraic properties of Poisson brackets on non-associative non-commutative algebras, compatible with their multiplicative structure. Special attention is paid to the Poisson brackets of the Lie-Poisson type, related with the special Lie-structures on the differential-topological torus and brane algebras, generalizing those studied before by Novikov-Balinsky and Gelfand-Dorfman. Illustrative examples of Lie and Balinsky-Novikov algebras are discussed in detail. The non-associative structures (induced by derivation and endomorphism) of commutative algebras related to Lie and Balinsky-Novikov algebras are described in depth.
The American Dream meets the Chinese Dream: a corpus-driven phraseological analysis of news texts
Authors: Hou Zhide
Published: April 2018

This study is a corpus-driven examination of frequent lexical words and keywords in the news texts related to the American Dream and the Chinese Dream. Based on Sinclair’s (Sinclair, John McHardy. 2004. Trust the Text. Routledge: London) five categories of co-selection as framework, it discusses the patterns of co-selection across the corpora of news texts, with a particular focus on the cumulative effects of the co-construction of situated meanings and establishment of ideological positions associated with the two dreams. The corpus linguistic tool Wordsmith is used to generate frequent words and keywords for detailed concordance analysis along both syntagmatic and paradigmatic relations in order to indicate collocation, colligation, semantic preference, and semantic prosody. The findings demonstrate the individualistic home, work and education associations of the American Dream versus the collectivistic attributions of the Chinese Dream of national rejuvenation. The study not only confirms different cultural practices, but also reveals different social-historical conditions, and political influences associated with media representations of the American Dream and the Chinese Dream.
Mensch / Mikrochip
Authors: Homberg Michael
Published: April 2018

Vorspann

Digitalisierung und Globalisierung haben die Welt in den letzten 50 Jahren ebenso rasant wie tiefgreifend verändert. Beschleunigte Austauschbeziehungen, für die vor allem Errungenschaften der Mikroelektronik Pate stehen, prägen den Alltag und sind aus unserem Leben kaum noch wegzudenken. Die historische Forschung fängt gerade erst an, dieses faszinierende Themenfeld zu vermessen und wissenschaftlich zu erschließen. Michael Homberg verbindet die Geschichte der Computerindustrie mit der Geschichte der Migration und der Geschichte der Arbeit an der Wende vom 20. zum 21. Jahrhundert. Mit seinen Fragen, Perspektiven und Thesen liefert er wichtige Bausteine für eine transnationale Vorgeschichte unserer Gegenwart.
Effects of 6-hydroxydopamine on visual deprivation in the kitten striate cortex
Authors: Daw NW , Rader RK , Robertson TW , Ariel M
Published: April 2018

We tested the effects of 6-hydroxydopamine (6-OHDA) on two forms of visual deprivation--monocular and directional deprivation. In normal kittens monocular deprivation leads to a change in the ocular dominance histogram recorded from the visual cortex, and directional deprivation leads to a change in the percentage of directionally sensitive cells responding to the appropriate direction of movement. 6-OHDA was infused into the occipital cortex prior to the peak of the critical period for the effects of visual deprivation. In agreement with the results of Kasamatsu et al. (Kasamatsu, T., and J. D. Pettigrew (1979) J. Comp. Neurol. 185: 139–162; Kasamatsu, T., J. D. Pettigrew, and M. Ary (1979) J. Comp. Neurol. 185: 163–182), suture of one eye (monocular deprivation) after the 6-OHDA treatment did not lead to a shift in ocular dominance in the area of striate cortex infused. Moreover, rearing kittens in an environment continually moving past them in one direction (directional deprivation) did not lead to a change in the percentage of cells preferring movement in that direction. In both rearing procedures the 6-OHDA did not make the cells in the cortex nonspecific, compared to cells recorded from the cortex of animals reared similarly but without infusion of 6-OHDA. Monocular and directional deprivation are forms of visual deprivation with different critical periods, probably involving different synapses. Therefore, the effect of 6-OHDA on visual deprivation is a general one, involving more than one kind of visual deprivation. In both cases 6-OHDA abolishes the plasticity of the visual cortex.
Neuron-specific enolase as an index of neuronal regeneration and reinnervation
Authors: Kirino T , Brightman MW , Oertel WH , Schmechel DE , Marangos PJ
Published: April 2018

Neuron-specific enolase (NSE) is a glycolytic isoenzyme which is located in central and peripheral neurons and neuroendocrine cells. Another enolase isoenzyme, non-neuronal enolase (NNE), occurs in glial cells. The purpose of this study was to follow any changes in NSE and/or NNE in cranial motor neurons after separation of their cell bodies from their axon terminals. One hypoglossal nerve in the rat and the cynomolgus monkey was thus crushed or cut and, after a given period, the brains were perfusion fixed. Immunocytochemistry, using anti-rat NSE and NNE or anti-human NSE and NNE, was performed on Vibratome-sectioned specimens of the hypoglossal nuclei. In the rat, NSE immunostaining decreased in the affected neurons 2 to 10 days following axonal injury. The change was greatest on the 10th day. Twenty days following nerve crush. NSE staining began to recover on the operated side and by the 45th day had returned to normal levels. NSE changes in the monkey were similar to those in the rat. In rats, where the nerve was cut and the proximal stump was translocated to a normally innervated muscle to inhibit re-formation of synaptic contacts, the NSE remained low for 60 days after nerve injury. As NSE levels fell during degeneration, there was a slight increase in NNE in some of the monkey specimens but not in others; the NNE alterations were, therefore, equivocal. The results demonstrate that the content of NSE in neurons serves as a molecular marker of axon injury, regeneration, and target reinnervation.
Competence to form electrical connections is restricted to growing neurites in the snail, Helisoma
Authors: Hadley RD , Kater SB
Published: April 2018

Identified neurons of the snail, Helisoma, undergo extensive remodeling in response to axotomy, including the formation of specific sets of novel electrical connections. This communication addresses the question of why, under the conditions employed, some neurons readily form new connections with a single “test” neurons, whereas others do not. The present experiments are a test of the hypothesis that, for these adult neurons, competence to form electrical connections is restricted to pairs of neurons with interacting regions of active outgrowth. Morphological observations demonstrated profuse overlapping outgrowth from neurons which formed electrical connections, whereas neurons which did not connect displayed no simultaneous new outgrowth, although there could be regions of physical overlap or proximity. The causal relationship between growth and the ability to form new connections was tested more directly by two means: (1) Previously nonconnecting neurons were recruited into the connectivity pattern by axotomy-induced growth. (2) Previously connecting neurons did not connect when they were not induced to grow. Thus, growth or lack of growth is an effective discriminator for determining specific sets of interconnected neurons.
Clonal organization of the central nervous system of the frog. III. Clones stemming from individual blastomeres of the 128-, 256-, and 512- cell stages
Authors: Jacobson M
Published: April 2018

Horseradish peroxidase injected into individual blastomeres of 128-, 256-, and 512-cell embyros of Xenopus laevis was identified in cells of the central nervous system (CNS) at early to middle larval stages. Labeled cells were dispersed, mingled with unlabeled cells. Four boundaries in the CNS could be defined by the behavior of clones of labeled cells: in the transverse plane at the level of the isthmus; in the horizontal plane between dorsal and ventral regions extending the entire length of the CNS; in the dorsal midline extending the entire length; and in the ventral midline of rhombencephalon and spinal cord but absent more rostrally. Cells injected with HRP at the 512-cell stage produced clones that, with rare exceptions, did not cross any boundary, whereas labeled clones initiated at earlier stages frequently crossed boundaries. Axons and dendrites were not restricted by these boundaries. These boundaries subdivided the CNS into seven compartments, each of which was occupied exclusively by the descendants of a group of 14 to 26 blastomeres in the 512-cell embryo. These groups of blastomeres formed a bilaterally symmetrical pattern composed of a single anterior median group straddling the dorsal midline near the animal pole and three groups on each side. Because cells mingled in each compartment but not across compartmental boundaries, there was a one-to-one relationship between individual blastomeres and CNS compartments but one-many and many-one relationships between individual blastomeres and neuroanatomical subdivisions smaller than a compartment. There was no constant relationship between phenotypes of nerve cells and their ancestry from individual blastomeres of the 512- cell or earlier stages.
Laminin induces acetylcholine receptor aggregation on cultured myotubes and enhances the receptor aggregation activity of a neuronal factor
Authors: Vogel Z , Christian CN , Vigny M , Bauer HC , Sonderegger P , Daniels MP
Published: April 2018

The effect of several basement membrane components on the aggregation of acetylcholine (ACh) receptors on cultured myotubes was studied. Cultures were incubated for 16 to 24 hr with laminin, a heparan sulfate proteoglycan, collagen types IV and V, or fibronectin, alone, or together with medium conditioned by NG108–15 neuroblastoma X glioma hybrid cells (NCM). The number of ACh receptor aggregates per myotube was assayed by fluorescence microscopy of cultures stained with tetramethylrhodamine-labeled alpha-bungarotoxin. Laminin induced ACh receptor aggregation on primary rat myotubes and on myotubes formed by G8–1 clonal rat muscle cells. Laminin enhanced the receptor-aggregating activity of NCM in a concentration-dependent manner (0.6 to 6.0 micrograms/ml) and the number of aggregates formed in the presence of laminin and NCM together was greater than the sum of the aggregates induced by NCM and laminin separately. The aggregation factor in NCM is probably not laminin, since less than 10 ng/ml of laminin-like immunoreactivity was detected in NCM, and antiserum against laminin blocked the effects of laminin but had little effect on NCM aggregation activity. Collagen type V enhanced the receptor aggregation activity of NCM, but less strongly than laminin, and had little or no effect by itself. The other basement membrane components did not induce receptor aggregation or enhance the effect of NCM. Experiments in which ACh receptors were labeled before exposure of cultures to NCM and laminin indicated that laminin enhanced the rearrangement of receptors at the cell surface. Immunofluorescence microscopy indicated that laminin binds to the myotubes within 30 min and forms patches on the cell surface over a period of hours. Laminin bound to the myotube surface enhanced receptor aggregation as well as laminin continuously present in the culture medium. The results suggest the possibility that laminin could enhance the receptor aggregation activity of a neuronal factor(s) released at the developing neuromuscular junction.
Functional synaptic circuits in the subplate during fetal and early postnatal development of cat visual cortex
Authors: Friauf E , McConnell SK , Shatz CJ
Published: April 2018

Among the first postmitotic cells of the cerebral cortex is a special population located below the cortical plate: the subplate neurons. These neurons reach a high degree of morphological maturity during fetal life, well before the neurons of the cortical layers have matured, yet nearly all of these cells die after birth in the cat. Subplate neurons are also known to receive synaptic contacts. Here we have investigated whether these contacts are functional by making intracellular recordings from subplate neurons in cortical slices maintained in vitro. Subplate neurons were identified based on their location and morphology by injecting them with biocytin following the intracellular recordings. At all ages studied between embryonic day 50 and postnatal day 9, electrical stimulation of the optic radiations elicited EPSPs and synaptic and antidromic spikes in subplate neurons, indicating that some of the synapses seen at the ultrastructural level are indeed capable of synaptic transmission. The spiking patterns of 39 morphologically identified subplate neurons were examined by injecting depolarizing current, which revealed that a large majority gave only a single spike or a brief train of spikes in response to maintained depolarization, in contrast to the regular spiking pattern found in many neurons of adult cortex. Biocytin injections into subplate neurons revealed that they are a morphologically heterogeneous population with respect to their dendritic branching patterns; roughly half were inverted pyramids, the classic subplate neuron morphology. The axonal processes of subplate neurons were remarkable in that many not only arborized within the subplate, but also entered the cortical plate and terminated in the marginal zone. At early postnatal ages, these axons also gave off collaterals within cortical layer 4. The results of this study indicate that subplate neurons participate in synaptic microcircuits during development. While the presynaptic identity of the input to subplate neurons is not known conclusively, it is likely that geniculocortical axons, which wait in close proximity to subplate neurons, contribute significantly. The pattern of axonal branching of subplate neurons also implies that information conferred to subplate neurons may be relayed, in turn, to the neurons of cortical layer 4. Finally with the death of subplate neurons, the geniculocortical axons leave the subplate and invade the cortical plate to innervate directly the neurons of layer 4. Thus, subplate neurons may function as a crucial, but transient synaptic link between waiting geniculocortical axons and their ultimate target cells in the cortex.
Identification of MARPP-58, a morphine- and cyclic AMP-regulated phosphoprotein of 58 kDa, as tyrosine hydroxylase: evidence for regulation of its expression by chronic morphine in the rat locus coeruleus
Authors: Guitart X , Hayward M , Nisenbaum LK , Beitner-Johnson DB , Haycock JW , Nestler EJ
Published: April 2018

Previously, we have identified a number of morphine- and cyclic AMP- regulated phosphoproteins (MARPPs) in the rat locus coeruleus (LC) and other brain regions. We now show that one of these phosphoproteins, a 58 kDa protein designated MARPP-58, is tyrosine hydroxylase. First, MARPP-58 comigrates with immunolabeled, immunoprecipitated, and purified tyrosine hydroxylase on 1- and 2-dimensional electrophoresis. Second, MARPP-58, immunoprecipitated tyrosine hydroxylase, and purified tyrosine hydroxylase yield identical 1-dimensional phosphopeptide maps. Third, MARPP-58 exhibits a regional and subcellular distribution in brain consistent with tyrosine hydroxylase. Identification of MARPP-58 as tyrosine hydroxylase made it possible to determine whether increases in MARPP-58 phosphorylation induced by chronic morphine in the LC reported previously are associated with alterations in enzyme activity and expression in this brain region. We show that chronic treatment of rats with morphine increases levels of tyrosine hydroxylase activity, immunoreactivity, and mRNA in the LC. Induction of the enzyme by chronic morphine was blocked by concomitant treatment of rats with the opiate receptor antagonist naltrexone, indicating that morphine produces this effect through the activation of opiate receptors. Consistent with previous observations that the chronic morphine-induced change in MARPP-58 phosphorylation is specific to the LC, changes observed in enzyme activity, immunoreactivity, and mRNA were not observed in a number of other brain regions studied. The results indicate that chronic morphine regulates the expression of tyrosine hydroxylase specifically in the LC and suggest that such regulation reflects long-term adaptations of LC neurons to chronic morphine at the level of gene expression.
Neuromuscular junctions shrink and expand as muscle fiber size is manipulated: in vivo observations in the androgen-sensitive bulbocavernosus muscle of mice
Authors: Balice-Gordon RJ , Breedlove SM , Bernstein S , Lichtman JW
Published: April 2018

Neuromuscular synapses in an androgen-sensitive muscle of sexually mature male mice were repeatedly observed over several-month intervals in normal animals and in animals in which testosterone levels were manipulated. In normal bulbocavernosus muscles, pre- and postsynaptic regions of neuromuscular junctions enlarge as muscle fibers grow. After castration, junctional area decreased in parallel with muscle fiber atrophy. When testosterone was resupplied to castrated animals, junctions that previously decreased in size then enlarged in parallel with muscle fiber hypertrophy. Surprisingly, these size changes occurred without loss or addition of motor nerve terminal branches or acetylcholine (ACh) receptor regions. Rather, each nerve terminal branch and underlying receptor region became smaller following castration and reenlarged following testosterone treatment. Several lines of evidence argued that the size changes observed after castration and testosterone treatment were secondary to shrinkage and stretching of the postsynaptic muscle fiber membrane. Following castration, the spaces between synaptic regions decreased in size at the same time and to a similar extent as the regions themselves. Following testosterone replacement, the spaces between synaptic regions expanded and each existing ACh receptor region enlarged. Ultrastructural analysis showed that there was no loss or addition of postsynaptic secondary junctional folds in the muscle fiber membrane (where ACh receptors are located) as junctions shrank and expanded. Rather, folds became more densely packed as muscle fibers atrophied following castration and less densely packed as muscle fibers hypertrophied following testosterone replacement. From these studies of the bulbocavernosus muscle, as from our previous studies of the sternomastoid muscle, we conclude that neuromuscular junction size is directly coupled to muscle fiber size. Androgens modulate muscle fiber volume directly, leading to a change in the surface area of the muscle fiber membrane, which in turn causes the postsynaptic specializations to shrink or expand. The concomitant shrinkage and stretching of motor nerve terminals that we observed can only be accounted for by their adhesion to postsynaptic specializations that are also changing size. Thus adhesion, rather than an interchange of diffusible factors, trophic or otherwise, is likely to be the primary determinant of coordinated pre- and postsynaptic enlargement in growing mammalian skeletal muscles.
Endogenous modulation of ACh release by somatostatin and the differential roles of Ca2+ channels
Authors: Gray DB , Zelazny D , Manthay N , Pilar G
Published: April 2018

In cats, spinal and medullary input to the thalamic nucleus submedius (Sm) arises almost exclusively from neurons in the marginal zone. As a result, it has been proposed that Sm may be specifically involved in nociception. In the present study, we determined the locations of neurons in the spinal cord and caudal medulla that project to Sm in rats. Iontophoretic injections of Fluoro-Gold or pressure injections of Fast blue were made into Sm. In each of the 6 rats that received small injections of Fluoro-Gold into Sm, only a small number (mean = 90) of retrogradely labeled neurons were found throughout the 18 segments of the spinal cord examined. Surprisingly, almost no labeled neurons (less than 1%) were counted in the marginal zone of the spinal cord. The majority were located in the deep dorsal horn and intermediate zone/ventral horn. In contrast, many neurons were labeled in the marginal zone of nucleus caudalis. Injections of Fluoro-Gold into any of a number of nuclei near Sm also labeled only a small number of neurons in the spinal cord and almost no neurons in the marginal zone. Using identical injection parameters, we injected Fluoro-Gold into the ventrobasal complex or posterior thalamic group. Hundreds of neurons in the spinal cord, including many in the marginal zone, were labeled following these injections. These results indicate that the techniques used to inject Fluoro-Gold into Sm were capable of labeling many projection neurons, including those in the marginal zone. Larger pressure injections of Fast blue were also made into Sm of 3 rats. The distribution of labeled neurons in nucleus caudalis and the spinal cord was similar to that following iontophoretic injections of Fluoro-Gold. Again, few marginal zone neurons were labeled in the spinal cord in any of these rats. Therefore, our results indicate that few spinothalamic tract neurons appear to project to Sm or any of several adjacent nuclei, and virtually no marginal zone neurons in the spinal cord project to these areas.
Axon guidance in muscleless chick wings: the role of muscle cells in motoneuronal pathway selection and muscle nerve formation
Authors: Phelan KA , Hollyday M
Published: April 2018

The role of myogenic cells in accurate pathway selection and muscle nerve formation was studied in chick embryos. Myotubes were eliminated from the forelimb of the chick embryo by extirpating the somites, which give rise to myogenic cells. Other elements of the wing tissue, connective tissue, and cartilagenous elements derived from the somatopleure, were left intact. Injections of WGA-HRP were made into either dorsal or ventral nerve trunks in the wing and the positions of retrogradely labeled motoneurons determined. The positions of the motoneurons within the brachial lateral motor column were appropriate for the injection made. Thus, the accuracy of the motoneuronal projections was unaffected by the absence of muscle cells. The absence of myotubes was not correlated with the absence of muscle nerves. Muscle nerves were consistently observed in muscleless wings until stage 36, the oldest stage examined. Muscle nerves in muscleless wings differed from those in normal wings in that they were smooth and stubby, and lacked the normal pattern of intramuscular nerve branches. From these studies we conclude that muscle cells are not necessary for accurate motor axon guidance into the periphery along the routes of major nerve trunks, nor for the formation of muscle nerves. By inference, somatopleural derivatives provide sufficient cues for selection of specific axonal pathways and for patterning of muscle nerves within the chick limb.
Dynamic alterations in the cutaneous mechanoreceptive fields of dorsal horn neurons in the rat spinal cord
Authors: Woolf CJ , King AE
Published: April 2018

The effect of the application to the skin of the chemical irritant mustard oil on the size and responsiveness of the cutaneous mechanoreceptive fields of 32 lumbar dorsal horn neurons has been examined in the adult decerebrate, spinal rat. Mustard oil placed on a small region of skin outside the mechanoreceptive firing zone produced a brief (185 +/- 35 sec, SEM) discharge of action potentials in 17 neurons and, in 23 cells, a prolonged increase of the response to a standard low- or high-intensity mechanical stimulus applied to the firing zone of the receptive field. This increase was shown, in 6 intracellularly recorded cells, to be due to a significantly increased depolarization in response to the stimuli. An expansion of the mechanoreceptive firing zones that peaked at 26 +/- 3.7 min was seen in 21 cells. While 6 of 8 nociceptive-specific neurons and 11 of 18 multireceptive neurons showed such an expansion, it did not occur in the 6 cells with low-threshold-only receptive fields. The expansion of the firing zones in 4 intracellularly recorded cells was found to be due to an increased amplitude of the EPSPs evoked by stimuli applied to what had initially been low probability firing fringes (Woolf and King, 1989) outside the firing zones, so that subthreshold responses became suprathreshold after application of the mustard oil. In 4 of 8 nociceptive-specific cells, the mechanical threshold in the firing zone became reduced to innocuous levels after application of the mustard oil. The demonstration of the capacity of a relatively brief afferent barrage of chemosensitive nociceptors to produce an increase in the spatial extent of the cutaneous receptive fields of dorsal horn neurons, amplify their responsiveness, and reduce their thresholds has implications both for the pathogenesis of postinjury pain hypersensitivity phenomena and for receptive field plasticity in the somatosensory system.
Circadian fluctuations of period protein immunoreactivity in the CNS and the visual system of Drosophila
Authors: Zerr DM , Hall JC , Rosbash M , Siwicki KK
Published: April 2018

When the protein encoded by the period (per) gene, which influences circadian rhythms in Drosophila melanogaster, was labeled with an anti- per antibody in adult flies sectioned at different times of day, regular fluctuations in the intensity of immunoreactivity were observed in cells of the visual system and central brain. These fluctuations persisted in constant darkness. Time courses of the changing levels of staining were altered in the per-short mutant: in light/dark cycles, the phase was earlier than in wild-type, and in constant darkness the period was shorter. In a per-long mutant and in behaviorally subnormal germline transformants (involving transduced per DNA), staining intensities were much fainter than in wild-type. Factors involved in initiating or maintaining the per protein cycling were investigated by examining the immunoreactivity in visual system mutants and by exposing wild-type flies to altered light/dark regimes. These genetic and environmental manipulations affected the expression of the per protein in ways that usually parallelled their effects on circadian behaviors.
Novel localization of a G protein, Gz-alpha, in neurons of brain and retina
Authors: Hinton DR , Blanks JC , Fong HK , Casey PJ , Hildebrandt E , Simons MI
Published: April 2018

Recently, a cDNA coding for a novel G protein alpha-subunit, Gz-alpha, was isolated from a human retinal cDNA library and shown by Northern blot analysis to be expressed at high levels in neural tissues. We have prepared affinity-purified antibodies specifically directed against synthetic Gz-alpha peptides and employed immunohistochemical methods to map the localization of Gz-alpha in human, bovine, and murine retina and brain. By light microscopy, Gz-alpha was localized to the cytoplasm of neurons, with predominant reactivity in ganglion cells of the retina, Purkinje cells of the cerebellum, and most neurons of the hippocampus and cerebral cortex. Reactivity was confined to perikaryon, dendrites, and a very short segment of proximal axons, except for the retinal ganglion cells, in which the axons in the nerve fiber layer showed intense Gz-alpha immunoreactivity proximal to the lamina cribrosa. Pre-embedding immunoelectron microscopy demonstrated the presence of focal Gz-alpha immunoreactivity on the nuclear membranes, endoplasmic reticulum, and plasma membranes of Purkinje cell perikarya and in association with microtubules in their proximal dendrites. Subcellular fractionation studies confirmed the association of Gz-alpha with plasma and intracellular membranes. The localization of Gz-alpha and its unique amino acid sequence suggest that it may have a specialized function in neural tissues.
Expression of functional mouse muscle acetylcholine receptors in Chinese hamster ovary cells
Authors: Forsayeth JR , Franco A , Rossi AB , Lansman JB , Hall ZW
Published: April 2018

CHO cells were transfected with cDNAs for all 4 subunits of the mouse muscle acetylcholine receptor (AChR) to obtain a stable cell line (CHO- AR) expressing the AChR on its surface. Immunoprecipitation experiments established that the AChR contained alpha- and beta-subunits assembled with gamma- and/or delta-subunits. In addition, one of the toxin- binding sites of the AChR was blocked by a myasthenic serum that specifically recognizes AChR containing the gamma-subunit. AChR from the CHO-AR cells had the same sedimentation rate, association rate constant for the binding of alpha-bungarotoxin (alpha BTX), and the same metabolic half-life as the AChR in myotubes of the mouse muscle cell line C2C12. Electrophysiological assay of CHO-AR cells by single- channel recording showed the presence of ACh-responsive ion channels with the characteristics of the embryonic AChR (gamma = 40 pS, tau = 5.6 msec). In some patches a smaller conductance channel was also seen that may represent partially assembled receptor. Fluorescence microscopy of fixed, permeabilized cells stained with rhodamine-alpha- BTX demonstrated both perinuclear and diffuse surface staining. The expression of fully assembled, functional mammalian muscle AChR in nonmuscle cells will allow detailed investigation of its properties and interactions with other cellular components.
Functional organization of input from areas 17 and 18 to an extrastriate area in the cat
Authors: Sherk H
Published: April 2018

In the cat, areas 17 and 18 have 2 main cortical targets: area 19 and a large region of suprasylvian cortex, referred to here as the Clare- Bishop area (Hubel and Wiesel, 1969). The functional organization of the latter area is not well understood. It seems likely that its organization reflects, in part, the organization of its inputs from areas 17 and 18, and I therefore studied the functional organization of these inputs. Responses were recorded directly from afferents terminating in the Clare-Bishop area after silencing its cells by local injections of kainic acid. Afferents were precisely ordered according to preferred orientation in a fashion resembling the columnar organization of area 17. Preferred direction was also an important organizing parameter. Within sizable regions of cortex, directional preference changed gradually or not at all, while at these regions' boundaries, preferred direction reversed by 180 degrees. Except for a loose grouping according to eye dominance, afferents were not ordered according to other response properties. It is possible that the afferent array is also compartmentalized according to the area of origin of each afferent. Inputs from areas 17 and 18, for example, might end in separate territories in the Clare-Bishop area. However, physiological recording, as well as anatomical experiments, failed to show a clear segregation. This study provides the first direct demonstration that a cortico-cortical pathway can be organized according to particular response properties. While the existence of an organization according to preferred orientation was not surprising, the high degree of order was unexpected. It is also interesting that afferents were well ordered according to 1 parameter, directional preference, that is weakly organized, at best, in area 17.
Functional organization in the ferret visual cortex: a double-label 2- deoxyglucose study
Authors: Redies C , Diksic M , Riml H
Published: April 2018

The functional organization of visual cortical area 17/18 of the ferret was studied using a double-label 2-deoxyglucose (2-DG) method. Animals were stimulated sequentially with moving gratings of 2 different orientations. Elongated orientational patches running roughly at a right angle into the area 17/18 border were seen. The orientation maps were similar in areas 17 and 18. When animals were stimulated with 2 orthogonally oriented gratings, activation patterns were not fully complementary but did not overlap. A complex pattern of partial overlap was observed, with orientations differing by 45 degrees. More gradual and more abrupt changes alternated frequently on a scale smaller than the average periodicity in the patterns. A cortical patch representing a given orientation was regularly surrounded by both neighboring and orthogonal orientations. The direction of the orientational changes reversed frequently in the immediate vicinity of any orientational patch. Orientation maps were compared with complete maps of retino- cortical projections obtained by transneuronal labeling with intravitreally injected tritiated proline. Ocular dominance in the binocular segment of both areas 17 and 18 was found to be organized into elongated ipsilateral islands in an almost contiguous contralateral projection. In area 18, the patches were wider than in area 17, and the ipsilateral islands were smaller in the regions representing the upper and central visual field than in those representing the lower visual field.
Selective impairment of slow axonal transport after optic nerve injury in adult rats
Authors: McKerracher L , Vidal-Sanz M , Essagian C , Aguayo AJ
Published: April 2018

To investigate cellular responses of injured mammalian CNS neurons, we examined the slow transport of cytoskeletal proteins in rat retinal ganglion cell (RGC) axons within the ocular stump of optic nerves that were crushed intracranially. RGC proteins were labeled by an intravitreal injection of 35S-methionine, and optic nerves were examined by SDS PAGE at different times after injury. In one group of rats, the RGC proteins were labeled 1 week after crushing. From 14 to 67 d after axotomy, the labeling of tubulin and neurofilaments was reduced in relation to other labeled proteins and to the labeling of tubulin and neurofilaments in the intact optic nerve of controls. To determine whether this reduction in labeling was due to an alteration in axonal transport after axotomy, we prelabeled RGC proteins 1 week before crushing. In such experiments, the rate of slow axonal transport of tubulin and neurofilaments decreased approximately 10-fold from 6 to 60 d after injury. Our results cannot be due only to the retrograde degeneration of RGCs and injured axons caused by axotomy in the optic nerve, because fast axonal protein transport and the fluorescent labeling of many axons were preserved in the ocular stumps of these optic nerves. This selective failure of the slow axonal transport of tubulin and neurofilaments may affect the renewal of the cytoskeleton and contribute to the gradual degeneration of RGCs that is observed after axotomy. The alterations in slow transport we document here differ from the enhanced rates we previously reported when injured RGC axons regenerated along peripheral nerve segments grafted to the ocular stump of transected optic nerves (McKerracher et al., 1990).
Carboxypeptidase E (enkephalin convertase): mRNA distribution in rat brain by in situ hybridization
Authors: MacCumber MW , Snyder SH , Ross CA
Published: April 2018

Carboxypeptidase E (CPE), also referred to as enkephalin convertase or carboxypeptidase H (EC 3.4.17.10), is present in neurotransmitter secretory granules and can remove C-terminal basic residues following endopeptidase cleavage during peptide processing. Using in situ hybridization with 35S-labeled oligonucleotide probes, we have mapped the localization of CPE mRNA in the rat brain. Specificity for CPE was confirmed by control experiments, which included production of identical patterns hybridization with 3 different antisense oligonucleotide probes, loss of label with RNase pretreatment of sections or co-incubation with excess unlabeled probe, and lack of labeling with sense orientation probes. In addition, the regional distribution of CPE mRNA by Northern blot analysis corresponded with distribution of labeling by in situ hybridization. The highest levels of CPE mRNA were found to be present in the pyramidal cells of the hippocampus, the pituitary anterior and intermediate lobes, the ependymal cells of the lateral ventricle, the endopiriform nucleus, the basolateral amygdala, the supraoptic nucleus, and the paraventricular nucleus. Intermediate levels were present in the thalamus, medial geniculate nucleus, lateral septal nucleus, piriform and entorhinal cortex, nucleus of the tractus solitarius, cerebellar cortex, pontine nuclei, and inferior olive. The lowest levels were found in the hippocampal granule cell layer, lateral hypothalamus, globus pallidus, and brain stem reticular formation. Ibotenic acid lesions of the hippocampus eliminated the majority of the label, which had been present over pyramidal cells, though labeling was increased over areas of reactive gliosis, suggesting that activated astrocytes can also synthesize CPE mRNA. In general, the localization of CPE mRNA in the rat brain corresponded to the distribution of enkephalin and other peptide neurotransmitter-synthesizing neurons, though CPE mRNA was also present in neurons that do not secrete known peptides and in reactive glia. The widespread yet specific localization of CPE mRNA in the rat brain suggests it may be an excellent marker for peptide synthesizing cells in the CNS.
Voltage-sensitive potassium channels in Drosophila photoreceptors
Authors: Hardie RC
Published: April 2018

A preparation of dissociated Drosophila ommatidia is described that allows single-channel and whole-cell patch-clamp analysis of currents in identified sensory neurons. Three distinct classes of voltage- sensitive potassium conductances are characterized; all were detected in distal parts of ommatidia from sevenless mutants and hence in one cell class (R1-6 photoreceptors). Rapidly inactivating A-channels (IA), coded by the Shaker gene, were isolated in multichannel patches from adult flies. While showing similar kinetics to muscle A-channels, they differ from previously characterized wild-type Shaker channels in having a much more negative voltage operating range, being half- inactivated at approximately -70 mV. Two delayed rectifier conductances were characterized in whole-cell recordings from pupal photoreceptors. The most commonly encountered class (IKs) is similar to previously reported delayed rectifier conductances in Drosophila. It inactivates slowly (time constant, approximately 500 msec) and is half-inactivated at approximately -40 mV. A more rapidly inactivating delayed rectifier (IKf) was detected in approximately 30% of cells; it is half- inactivated at approximately -80 mV. Both IKs and IKf are blocked by 100 microM quinidine. Neither are greatly affected by 4-aminopyridine, which blocks IA at 1-5 mM. None of the three conductances was calcium dependent, nor were they obviously affected by the eag mutation, which affects K channels in muscle. The developmental profile of the channels is the inverse of that described in muscle. Both IKs and IKf are present at the earliest pupal stages examined (approximately 60 hr), but IA was only first detected at approximately 76 hr.(ABSTRACT TRUNCATED AT 250 WORDS)
Behavioral sensitization to kainic acid and quisqualic acid in mice: comparison to NMDA and substance P responses
Authors: Sun XF , Larson AA
Published: April 2018

Substance P (SP) and the excitatory amino acid (EAA) agonists NMDA, kainic acid (KA), or quisqualic acid (Quis) each produce a transient, caudally directed biting and scratching response (CBS) in mice after their intrathecal injection. We have previously shown that repeated injections of SP result in a decrease in the intensity of CBS, or desensitization. The goals of the present study were (1) to determine whether desensitization also develops to the CBS behavior produced by EAAs in the spinal cord, (2) to characterize the role of interneurons in desensitization, and (3) to examine possible interactions between EAAs and SP. While injection of NMDA at 2 min intervals resulted in desensitization to its CBS behavioral effect, behavioral responses to repeated injections of KA or Quis increased in intensity, exhibiting sensitization. The NMDA antagonist DL-2-amino-5-phosphonovaleric acid failed to alter sensitization to either KA or Quis but inhibited behaviors produced by SP and NMDA, suggesting an NMDA-mediated component in SP-induced behavior. Concanavalin A, which is reported to block desensitization to the electrophysiologic effect of Quis, blocked sensitization to the behavioral effects of both Quis and KA. Strychnine, bicuculline, and 5-aminovaleric acid each inhibited desensitization to SP and NMDA, supporting the notion of recruitment of inhibitory transmitters in the attenuation of NMDA and SP activity. Pretreatment with capsaicin selectively inhibited the development of behavioral sensitization to KA, suggesting an involvement of small- diameter C-fibers in the enhancement of responsivity to KA. Consistent with this, pretreatment with SP selectively potentiated the CBS response to KA. The potentiation of KA effects by SP and dependence of KA behavioral sensitization on C-fiber activity suggest a possible mechanism by which EAAs and SP may be involved in the mediation of pain.
Effects of locus coeruleus activation on electroencephalographic activity in neocortex and hippocampus
Authors: Berridge CW , Foote SL
Published: April 2018

Experiments were conducted to examine the hypothesis that increased neuronal discharge activity of noradrenergic neurons of the locus coeruleus (LC) above resting discharge rates can alter forebrain electroencephalographic (EEG) activity. Small infusions (70-135 nl) of the cholinergic agonist bethanechol within 500 microns of the LC were used to activate this nucleus reversibly in halothane-anesthetized rats. A combined recording-infusion probe allowed verification of this electrophysiological activation. Simultaneously, EEG activity was recorded from sites in the frontal cortex and hippocampus and subjected to power-spectrum analyses. The findings were (1) LC activation was consistently followed, within 5 to 30 sec, by a shift from low- frequency, high-amplitude to high-frequency, low-amplitude EEG activity in frontal neocortex and by the appearance of intense theta-rhythm in the hippocampus; (2) forebrain EEG changes followed LC activation with similar latencies whether infusions were made lateral or medial to the LC; (3) infusions placed outside the immediate vicinity of the LC were not followed by these forebrain EEG effects; (4) following infusion- induced activation, forebrain EEG returned to preinfusion patterns with about the same time course as the recovery of LC activity (10-20 min for complete recovery). These infusion-induced effects on EEG activity were blocked or severely attenuated by pretreatment with the alpha 2- agonist clonidine, which inhibits LC discharge and norepinephrine release, or the beta-antagonist propranolol. These observations indicate that enhanced LC discharge activity is the crucial mediating event for the infusion-induced changes in forebrain EEG activity observed under these conditions and suggest that LC activation may be sufficient to induce EEG signs of cortical and hippocampal activation.
Identification and localization of muscarinic acetylcholine receptor proteins in brain with subtype-specific antibodies
Authors: Levey AI , Kitt CA , Simonds WF , Price DL , Brann MR
Published: April 2018

mRNAs encoding five genetically distinct muscarinic ACh receptors are present in the CNS. Because of their pharmacological similarities, it has not been possible to detect the individual encoded proteins; thus, their physiological functions are not well defined. To characterize the family of proteins, a panel of subtype-selective antibodies was generated against recombinant muscarinic receptor proteins and shown to bind specifically to each of the cloned receptors. Using immunoprecipitation, three receptor proteins (m1, m2, and m4) accounted for the vast majority of the total solubilized muscarinic binding sites in rat brain. These receptor subtypes had marked differences in regional and cellular localization as shown by immunocytochemistry. The m1-protein was present in cortex and striatum and was localized to cell bodies and neurites, consistent with its role as a major postsynaptic muscarinic receptor. The m2-receptor protein was abundant in basal forebrain, scattered striatal neurons, mesopontine tegmentum, and cranial motor nuclei; this distribution is similar to that of cholinergic neurons and suggests that m2 is an autoreceptor. However, m2 was also present in noncholinergic cortical and subcortical structures, providing evidence that this subtype may presynaptically modulate release of other neurotransmitters and/or function postsynaptically. The m4-receptor was enriched in neostriatum, olfactory tubercle, and islands of Calleja, indicating an important role in extrapyramidal function. These results clarify the roles of these genetically defined receptor proteins in cholinergic transmission in brain.(ABSTRACT TRUNCATED AT 250 WORDS)
Growth cone behavior underlying the development of stereotypic synaptic connections in Drosophila embryos
Authors: Halpern ME , Chiba A , Johansen J , Keshishian H
Published: April 2018

Each muscle fiber in the segmented body wall of Drosophila larvae is innervated by anatomically stereotyped neuromuscular junctions. These synapses arise through the selective choices of motoneuronal growth cones at their peripheral targets. Using digital optical microscopy of staged intracellular dye fills, we have singly identified embryonic motoneurons and have examined individual growth cones when they contact and differentiate at the target cells. There is a precise connectivity between motoneuron and muscle fiber, which is the direct consequence of growth cone behavior. We have also found that Drosophila muscle fibers possess molecularly heterogeneous cell surfaces that may be involved in growth cone recognition of appropriate targets. Fasciclin III, a homophilic adhesion molecule, is coexpressed by several of the efferent growth cones and in a site-specific fashion by the target muscle fiber's membrane. The fasciclin III expression is transient, corresponding to the period in embryogenesis when the first neuromuscular contacts are made. Upon encountering the target cell surface, the growth cones can sprout stereotypically arrayed filopodial processes, orient along the anterior-posterior axis, and turn in predictable directions. Subsequently, terminal branches are established in a nonrandom order. These phenomena were found to occur in two motoneurons that innervate adjacent muscle fiber targets, and may be general features of neuromuscular synaptogenesis in Drosophila.