60 research outputs found
Detection of Naphthalene Sulfonates from Highly Saline Brines with High-Performance Liquid Chromatography in Conjunction with Fluorescence Detection and Solid-Phase Extraction
No full textGerman Federal Ministry of Environment (BMU) [FKZ: 0327579
Bilateral organization of the vocal control pathway in the budgerigar, Melopsittacus undulatus
No full textAnatomical and electrophysiological methods were used to map the vocal control nuclei of the budgerigar, Melopsittacus undulatus. Beginning with the motor nucleus of the syrinx, nuclei were located using antidromic stimulation and then injected with horseradish peroxidase (HRP). Retrogradely transported HRP labeled afferents to the injected nucleus. This procedure was repeated at successively higher levels along the vocal pathway. Connections found using this strategy then were confirmed using anterograde transport of HRP and/or tritiated proline and orthodromic electrical stimulation. We found that the primary vocal control pathway consisted of (1) the motor nucleus innervating the trachea and syrinx, nXIIts; (2) an archistriatal nucleus, RA; and (3) a neostriatal nucleus, “HVc.” These nuclei correspond to similar, possibly homologous, nuclei in the vocal control pathway of the canary (Nottebohm, F., T. M. Stokes, and C. M. Leonard (1976) J. Comp. Neurol. 165: 457–486) but, because of differences in gross brain morphology, are displaced considerably in absolute position. Furthermore, the projection from RA to the motor nucleus is bilateral in the budgerigar, whereas the same connection is strictly ipsilateral in the canary. The projection of the motor nucleus to muscles of the vocal organ is also bilateral in the budgerigar (Manogue, K. R., and F. Nottebohm (1981) J. Compl. Neurol., in press) but ipsilateral in the canary. the possible significance of these species differences for lateralization of motor control is discussed.</jats:p
Mapping of radial glia and of a new cell type in adult canary brain
No full textFrontal and coronal sections of adult male and female canary brain were stained with a monoclonal antibody to vimentin using an immunoperoxidase technique; some sections were counterstained with cresyl violet. The position of radial glia cells was mapped using a computer-linked microscope. The telencephalon was found to have a rich set of radial glia. The long processes of these radial glia showed a mediolateral orientation, and were much more abundant in some parts of the telencephalon (e.g., hyperstriatum, caudal neostriatum, and lobus parolfactorius) than in others (e.g., anterior neostriatum, archistriatum, and septum), which had few or no radial glia fibers. A small, elongated cell type not previously described in adult avian brain was frequently seen to be associated with the long processes of the radial glia, oriented in the same direction and often in close apposition. The position of these cells was also systematically mapped, and they were found to be virtually absent outside of the telencephalon. The relation between radial glia fibers and the small, elongated cells was most commonly seen close to the lateral ventricle of the forebrain, where the radial glia cells have their cell bodies. The above observations suggest that there may be a functional relation between radial glia and the small, elongated cells. We hypothesize that the latter cells are young migrating neurons. This hypothesis is tested in a separate publication (A. Alvarez-Buylla and F. Nottebohm, unpublished observations).</jats:p
A comparison between the dispute settlement procedures in the international court of justice and the world trade organisation
No full textThis thesis was submitted for the degree of Master of Philosophy and awarded by Brunel University.The International Court of Justice (ICJ) came into being due to a perceived need for international judicial settlement, whereas the World Trade Organisation (WTO) was created for the purpose of specifically promoting international trade by reducing tariffs and other barriers to trade. Alternative structures for each institution are also considered, as is the older dispute settlement process of arbitration, by means of cases. It is a voluntary submission by both parties to a dispute, when they have agreed on the issues, but need external assistance to proceed further. As a type of judicial settlement, it is binding, can permit third party or non-state involvement, and is a precursor of international tribunals.
In the WTO, one aim is to use cases to test conceptual points. The specific aspects of dispute settlement including the application of rules and procedures, and implementation and processes, will be discussed. The working procedures of the Appellate Body (AB) will be analysed in detail. Another aim is to compare with the ICJ, wherever possible. Legal concepts such as jurisdiction, judicial aspects of reasoning, the burden of proof, and the standard of proof will be discussed. The Appellate Body’s (AB’s) standard of review of panel recommendations and rulings will be analysed. Compliance and enforcement are compared between the two organisations. Economic and political considerations will also be touched on when relevant to this study.
In the ICJ, the application of concepts such as judicial restraint and activism will be assessed, including the degree of inconsistency found in different cases. The implications of the different types of agreements between states that can lead to or have led to the ICJ’s jurisdiction will be examined, and the impacts assessed. The ambiguity involving provisional measures will be studied in detail. The ICJ’s relationship to the UN Security Council will also be assessed. The lack of monitoring or enforcement, and of no stated compliance timeframe are considered. The thesis will end with various future recommendations
FnTm2, a novel transcript dynamically expressed in the song learning circuit of the zebra finch
No full textSeasonal changes in patterns of gene expression in avian song control brain regions
No full textPhotoperiod and hormonal cues drive dramatic seasonal changes in structure and function of the avian song control system. Little is known, however, about the patterns of gene expression associated with seasonal changes. Here we address this issue by altering the hormonal and photoperiodic conditions in seasonally-breeding Gambel's white-crowned sparrows and extracting RNA from the telencephalic song control nuclei HVC and RA across multiple time points that capture different stages of growth and regression. We chose HVC and RA because while both nuclei change in volume across seasons, the cellular mechanisms underlying these changes differ. We thus hypothesized that different genes would be expressed between HVC and RA. We tested this by using the extracted RNA to perform a cDNA microarray hybridization developed by the SoNG initiative. We then validated these results using qRT-PCR. We found that 363 genes varied by more than 1.5 fold (>log(2) 0.585) in expression in HVC and/or RA. Supporting our hypothesis, only 59 of these 363 genes were found to vary in both nuclei, while 132 gene expression changes were HVC specific and 172 were RA specific. We then assigned many of these genes to functional categories relevant to the different mechanisms underlying seasonal change in HVC and RA, including neurogenesis, apoptosis, cell growth, dendrite arborization and axonal growth, angiogenesis, endocrinology, growth factors, and electrophysiology. This revealed categorical differences in the kinds of genes regulated in HVC and RA. These results show that different molecular programs underlie seasonal changes in HVC and RA, and that gene expression is time specific across different reproductive conditions. Our results provide insights into the complex molecular pathways that underlie adult neural plasticity
Computational inference of neural information flow networks
No full textThis research was supported by a Packard Foundation grant and a US National Science Foundation (NSF) Waterman Award to EDJ, an NSF CAREER grant and an Alfred P. Sloan Fellowship to AJH, and a US National Institutes of Health R01 DC7996 grant from National Institute on Deafness and Other Communication Disorders to support the collaboration between AJH and EDJ. The original collaboration between AJH and EDJ was supported by a Duke University Bioinformatics grant.Determining how information flows along anatomical brain pathways is a fundamental requirement for understanding how animals perceive their environments, learn, and behave. Attempts to reveal such neural information flow have been made using linear computational methods, but neural interactions are known to be nonlinear. Here, we demonstrate that a dynamic Bayesian network (DBN) inference algorithm we originally developed to infer nonlinear transcriptional regulatory networks from gene expression data collected with microarrays is also successful at inferring nonlinear neural information flow networks from electrophysiology data collected with microelectrode arrays. The inferred networks we recover from the songbird auditory pathway are correctly restricted to a subset of known anatomical paths, are consistent with timing of the system, and reveal both the importance of reciprocal feedback in auditory processing and greater information flow to higher-order auditory areas when birds hear natural as opposed to synthetic sounds. A linear method applied to the same data incorrectly produces networks with information flow to non-neural tissue and over paths known not to exist. To our knowledge, this study represents the first biologically validated demonstration of an algorithm to successfully infer neural information flow networks.Peer reviewe
ZENK activation in the nidopallium of black-capped chickadees in response to both conspecific and heterospecific calls
No full textNeuronal populations in the songbird nidopallium increase in activity the most to conspecific vocalizations relative to heterospecific songbird vocalizations or artificial stimuli such as tones. Here, we tested whether the difference in neural activity between conspecific and heterospecific vocalizations is due to acoustic differences or to the degree of phylogenetic relatedness of the species producing the vocalizations. To compare differences in neural responses of black-capped chickadees, Poecile atricapillus, to playback conditions we used a known marker for neural activity, ZENK, in the caudal medial nidopallium and caudomedial mesopallium. We used the acoustically complex ‘dee’ notes from chick-a-dee calls, and vocalizations from other heterospecific species similar in duration and spectral features. We tested the vocalizations from three heterospecific species (chestnut-backed chickadees, tufted titmice, and zebra finches), the vocalizations from conspecific individuals (black-capped chickadees), and reversed versions of the latter. There were no significant differences in the amount of expression between any of the groups except in the control condition, which resulted in significantly less neuronal activation. Our results suggest that, in certain cases, neuronal activity is not higher in response to conspecific than in response to heterospecific vocalizations for songbirds, but rather is sensitive to the acoustic features of the signal. Both acoustic features of the calls and the phylogenetic relationship between of the signaler and the receiver interact in the response of the nidopallium.Peer reviewe
Distribuição da imunorreatividade à doublecortina no prosencéfalo de pombos adultos (Columba livia): avaliação dos efeitos de diferentes condições de alojamento
No full textTCC(graduação) - Universidade Federal de Santa Catarina. Centro de Ciências Biológicas. Biologia.A doublecortina (DCX) é uma proteína associada a microtúbulos crítica para a migração radial e tangencial de neurônios imaturos, tanto no cérebro em desenvolvimento quanto no adulto. No cérebro de mamíferos adultos neurônios recém formados no hipocampo e da zona subventricular (SVZ) são imurreativos à DCX (DCX+). Oito pombos (Columba livia, Columbiformes), entre 8 e 10 meses de idade e peso corporal de 380 a 420g, foram alojados em duas diferentes condições ambientais (enriquecida, n=4 e nãoenriquecida, n=4). Após um período de 40 dias os animais foram perfundidos (com solução sacarose 9,25% seguida de de 4% paraformaldeído em PBS 0,01 M) sob overdose de anestesia (Cetamina e Xilazina). Os cérebros foram removidos e seccionados em criótomo a uma expessura de 50um. Essas secções foram então submetidas a reações imunohistoquímicas (anticorpo policlonal de coelho Anit-DCX, Abcam, secundário anti-coelho biotinilado revelado pelo método ABC, Vector, reação colorimétrica com DAB, Sigma) para marcação da DCX. As secções telencefálicas de quatro animais do ambiente não-enriquecido foram observadas sob microscópio óptico e fotografadas para a descrição da distribuição total de células e fibras imunorreativas à DCX. Secções contendo o hipocampo de todos os animais dos dois grupos experimentais foram, da mesma forma, observadas e fotografadas e as células DCX+ hipocampais foram contadas. Constatamos que doublecortina é amplamente distribuída no telencéfalo de pombos adultos. Observamos células e fibras DCX+ na SVZ, hipocampo, estriado, hyperpallium apicale, arcopallium, mesopallium, nidopallium, área septal e bulbo olfativo. Pudemos descrever também as vias principais de migração celular no prosencéfalo desse animais. Além disso nossos dados indicam que, como em roedores, existe diferença estatisticamente significante no número de células DCX+ hipocampais entre os dois grupos experimentais
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