A questão em torno do aquecimento global vem preocupando a sociedade mundial,sendo que os governantes e ambientalistas têm intensificado estudos e aplicações de medidas para tentar minimizar os efeitos das emissões de gases de efeito estufa na atmosfera. O setor de transporte é o segundo maior consumidor de energia, pois é muito dependente de combustíveis fósseis, que emitem quantidade elevada de CO2. O setor sucroenergético é um importante gerador de divisas para o país, sendo que a receita em 2010 foi de R$ 50 bilhões e as exportações alcançaram US$ 13,8 bilhões. O açúcar é um importante produto da pauta agrícola, o país exporta aproximadamente 70% da sua produção. O etanol é um importante gerador de energia, e consegue minimizar as suas emissões durante seu ciclo produtivo em até 90%, quando comparado a gasolina, seu principal concorrente. Dada a importância do transporte nas emissões de gases de efeito estufa e a possibilidade da mudança de modalidade reduzir essas emissões, o objetivo desta tese é estimar os benefícios da redução das emissões de CO2, a partir da mudança da matriz de transporte,para o setor sucroenergético. Para tanto foi utilizada a metodologia de programação linear, utilizando a otimização para a minimização das emissões e do custo de transporte. O softwar eutilizado foi o GAMS e quatro diferentes cenários para ambos os produtos foi traçado. O primeiro e o segundo foi modelado para a safra 2010/2011 e foi considerada a atual malha de transporte, sendo que a diferença entre os dois foi que no primeiro realizou-se a imposição da quantidade máxima de carga utilizando a intermodalidade com base no que foi escoado no ano 2010 e no segundo liberou-se esse volume. O objetivo é captar qual seria a configuração ideal tanto em termos econômicos como ambiental, caso não houvesse problemas estruturais e de infraestrutura para a utilização mais intensa de mais de um modal de transporte. No terceiro e quarto cenário foi utilizada uma estimativa para a safra 2020/2021, sendo que a diferença entre as duas modelagens foi que no terceiro manteve-se a mesma infraestrutura atualmente observada e no último expandiu-se as rotas intermodais passíveis de serem utilizadas considerando todas as obras de transporte apresentadas pela iniciativa privada, governo federal e as inseridas no Plano de Aceleração do Crescimento I e II. Os resultados apontaram um trade-off entre custo e emissão quando se compara os resultados da minimização das emissões e da minimização dos custos no mesmo cenário. No entanto, quando se confronta os resultados obtidos entre os cenários propostos verifica-se que é possível reduzir tanto os custos quanto as emissões para ambos os produtos. Para a safra 2020/2021, a simples possibilidade de se utilizar mais intensamente modais de transporte diferentes do rodoviário possibilitaria atingir em apenas três anos a redução de 6,6 milhões de toneladas de CO2 e R$ 3,3 bilhões no escoamento do açúcar e etanol. A mitigação através da mudança de modal poderia inserir o setor no mercado de carbono e conquistar mercados preocupados em obter produtos sustentáveis. / Global warming is a major and growing concern around the world, with governments and environmentalists intensifying studies involving measures aimed at minimizing the effects of greenhouse gas emissions into the atmosphere. Among major sectors, transportation is the second largest energy user and it remains highly dependent on fossil fuels that emit high amounts of CO2. The sugarcane industry is an important source of export revenues for Brazil: while total revenues for 2010 reached US$ 25 billion, about US$ 13.8 billion of that was generated by exports. Sugar is a key agricultural product on the Brazilian export agenda, with about 70% of production shipped to other countries. Ethanol, also produced from sugarcane, is a major ingredient of the countrys energy mix, which can also minimize emissions through its lifecycle by up to 90% compared to gasoline, its main competitor at the pump. Given the importance of transportation in greenhouse gas emissions and the possibility of diversifying transportation systems to achieve emission reductions, the goal of this thesis is to estimate the benefits the sugar-energy industry of reducing CO2 emissions through a diversification of transportation methods utilized by the industry. A methodology that relies on linear programming was used, aimed at optimization in order to minimize emissions and transportation costs. GAMS, a widely used software in linear programming, was utilized to construct four different scenarios for both products. Scenarios one and two covered the 2010/2011 harvest and considered the current transportation network, the difference being that scenario one considered a fixed cargo ceiling and various transport modes while scenario two, the cargo ceiling was eliminated. The idea was to arrive at an ideal configuration in both economic and environmental terms, considering no structural or infrastructure obstacles to more intense utilization of different modes of transport. Scenarios three and four relied on a long-range estimate for the 2020/2021 sugarcane harvest, the main difference between the two models being that model three is based on the same infrastructure that currently exists while model four considers an expansion of possible routes involving various transport modes that could be used, considering all transportation-related projects launched by private contractors and the federal government, including those that are a part of the governments Accelerated Growth Plans I and II, also known as PAC. The results point to a tradeoff between costs and emissions, when the results of minimizing emissions and costs within the same scenario are compared. However, when results between the proposed scenarios are pitted against one another, it can be concluded that it is possible to cut costs as well as emissions for both sugar and ethanol. In the 2020/2021 harvest, the simple possibility of utilizing a variety of road transport modes that dont involve road transportation would allow for a 6.6 million ton reduction in CO2 emissions, with a R$3.3 billion savings in cost of shipping sugar and ethanol. Mitigation through change transportation mode changes could finally insert the industry in carbon markets, while conquering markets where a greater concern with sustainability already exists.

Made available in DSpace on 2016-03-15T19:37:43Z (GMT). No. of bitstreams: 1 Luiz Antonio Carraro.pdf: 1226702 bytes, checksum: 3cef29694a4e26f233b0aae16da69cf0 (MD5) Previous issue date: 2012-02-16 / Universidade Presbiteriana Mackenzie / A container is a broadly used solution for the cargo storage to be transported between ports, playing a central role in international trade. Consequently, ships grew in size in order to maximize their container transportation capacity in each trip. Due to increasing demand, container terminals face the challenges of increasing their service capacity and optimizing the loading and unloading time of ships. Optimization problems, such as these, often present features that make it impossible to obtain closed analytical solutions, requiring iterative search procedures in high-dimensional spaces, or subject to a combinatorial explosion of possible solutions. This dissertation presents the proposal of a novel meta-heuristic based on the Clonal Selection Algorithm, named MRC, to minimize the number of reshuffles in operations involving piles of containers. The performance of the proposed model was evaluated through simulations and results comparison with those obtained by algorithms from the literature under the same test conditions. The results obtained show that MRC is competitive in terms of minimizing the need of reshuffles, besides presenting a reduced processing time compared with models of similar performance. / A utilização de contêineres é uma solução amplamente adotada para o armazenamento da carga a ser transportada entre portos, tornando-se de grande importância no comércio internacional e, consequentemente, navios cresceram de tamanho com o objetivo de transportar a maior quantidade possível de contêineres em cada viagem. Devido à crescente demanda, terminais de contêineres enfrentam os desafios de aumentar a sua capacidade de atendimento e otimizar os tempos de carregamento e descarregamento de navios. Problemas de otimização como estes geralmente apresentam características que inviabilizam a obtenção de soluções analíticas fechadas, requerendo processos iterativos de busca em espaços de dimensão muitas vezes elevada, ou ainda sujeitos a explosão combinatória de possíveis soluções. Esta dissertação apresenta a proposta de uma meta-heurística bioinspirada baseada no Algoritmo de Seleção Clonal para a minimização de rearranjos em operações que envolvem pilhas de contêineres, denominado MRC. O desempenho do algoritmo foi avaliado por meio de simulações e comparação dos resultados com os obtidos por algoritmos da literatura sob as mesmas condições de teste. Os resultados obtidos permitem concluir que o MRC possui resultados competitivos em termos de minimização de rearranjos, além de apresentar um tempo de processamento reduzido quando comparado aos modelos tradicionalmente empregados na solução desse tipo de problema.

Este estudo tem por objetivo avaliar o nível de desconforto, através da Escala Visual Analógica (EVA), o Mapa de Segmentos Corporais de Corlett e Bishop (MSC) e o Questionário de Fadiga de Chalder (EFC) em operadores de telemarketing. A coleta de dados foi realizada uma vez por semana, ao longo de 2 meses de aplicação do programa de exercícios. A análise estatística sugere diminuição do crescimento do desconforto postural nos dois grupos, sendo mais acentuada no grupo experimental. Foi observada também diminuição significativa dos níveis de EVA e redução da freqüência e da prevalência de segmentos doloridos no MSC, ao se comparar dados da primeira e da última semana do estudo realizado. Quanto à fadiga também houve melhora em todas as variáveis do questionário de Chalder, indicando presença de efeitos significativos na diminuição dos níveis de fadiga. Assim, os programa de exercícios mostraram-se efetivos para diminuir o desconforto músculo-esquelético e a fadiga entre os operadores de telemarketing / The objective of this survey is to assess the telemarketing operators discomfort and mental and physical fatigue at the airway company call center before and after applying an exercise program. The objective of this survey is to assess the telemarketing operators discomfort and mental and physical fatigue at the airway company call center before and after applying an exercise program. The body map of Corlett and Bishop with a visual analogic scale and the Chalder fatigue questionnaire was applied to 84 telemarketing operators from the experimental and control groups. The experimental group has attended a 10 minutes exercise daily session and the control group a 10 minutes daily rest break. The exercise showed that is more effective than a rest break to prevent discomfort development and is important to repetitive strain injuries prevention because discomfort is one of the main predictors of this group of diseases

Abstract In this thesis, bandwidth (BW) enhanced antennas for mobile terminals and multilayer ceramic packages are presented. The thesis is divided into two parts. In the first part, electrically frequency-tunable mobile terminal antennas have been studied. The first three antennas presented were of a dual-band planar inverted-F type (PIFA) and were tuned to operate in frequency bands appropriate to the GSM850 (824–894 MHz), GSM900 (880–960 MHz), GSM1800 (1710–1880 MHz), GSM1900 (1850–1990 MHz) and UMTS (1920–2170 MHz) cellular telecommunication standards with RF PIN diode switches. The first antenna utilized a frequency-tuning method developed in this thesis. The method was based on an integration of the tuning circuitry into the antenna. The tuning of the second antenna was based on a switchable parasitic antenna element. By combining the two frequency-tuning approaches, a third PIFA could be switched to operate in eight frequency bands. The planar monopole antennas researched were varactor-tunable for digital television signal reception (470–702 MHz) and RF PIN diode switchable dual-band antenna for operation at four cellular bands. The key advantage of the former antenna was a compact size (0.7 cm3), while for the latter one, a tuning circuit was implemented without using separate DC wiring for controlling the switch component. The second part of the thesis is devoted to multilayer ceramic package integrated microwave antennas. In the beginning, the use of a laser micro-machined embedded air cavity was proposed to enable antenna size to impedance bandwidth (BW) trade-off for a microwave microstrip in a multilayer monolithic ceramic media. It was shown that the BW of a 10 GHz antenna fabricated on a low temperature co-fired ceramic (LTCC) substrate could be doubled with this technique. Next, the implementation of a compact surface mountable LTCC antenna package operating near 10 GHz was described. The package was composed of a BW optimized stacked patch microstrip antenna and a wide-band vertical ball grid array (BGA)-via interconnection. Along with the electrical performance optimization, an accurate circuit model describing the antenna structure was presented. Finally, the use of low-sintering temperature non-linear dielectric Barium Strontium Titanate (BST) thick films was demonstrated in a folded slot antenna operating at 3 GHz and frequency-tuned with an integrated BST varactor.

La promotion du transport ferroviaire de marchandises permet d’améliorer l’impact environnemental du transport de marchandises, à travers la réduction de la part modale de la route, qui est responsable d’environ un quart des émissions européennes de CO2. L’objet de cette thèse est d’analyser les flux de marchandises afin de proposer des solutions opérationnelles qui permettraient d’augmenter la part de marché du transport de fret ferroviaire, notamment grâce à une meilleure utilisation des terminaux intermodaux. La première partie de la thèse fournit une synthèse des principales modèles théoriques concernant l’analyse de la demande et de l’offre de transport de marchandises, afin d’analyser le lien entre activité économique et transport de marchandises. Une analyse détaillée des sources statistiques disponibles au niveau européen, national et régional, est aussi fournie. Dans la deuxième partie, une application au cas des chantiers de transbordement rail-route en France est présentée, et une comparaison avec d’autres pays européens est réalisée. L’objectif de cette analyse est d’estimer la demande potentielle de transport combiné, d’évaluer la productivité des terminaux intermodaux et d’étudier l’impact socio-économique et financier des investissements dans les terminaux intermodaux, en évaluant également la possibilité des nouveaux montages financiers (PPP). Les résultats de l’analyse montrent un large potentiel pour le transport combiné, en particulier en lien avec l’activité des ports maritimes, et une productivité faible dans les terminaux existants. En conséquence, cette analyse suggèrerait de concentrer les investissements sur un nombre limité de sites à haut potentiel, afin d’attirer des investissements privés et optimiser l’utilisation des fonds publics. Les implications politiques de cette analyse sont multiples : elles concernent d’abord le gestionnaire d’infrastructure et les opérateurs ferroviaires, qui doivent mieux planifier les investissements en fonction de la demande commerciale. Elles concernent aussi l’Etat et les collectivités locales, qui doivent optimiser l’utilisation des fonds publics en favorisant les localisations à haut potentiel. / The promotion of railway modal share has large benefits on the environment by reducing the modal share of road transport, which is responsible for about one-fourth of European CO2 emissions. The aim of this dissertation is to analyse freight transport flows in order to provide operational solutions to increase the modal share of railways transport through a better use of intermodal terminals. In the first part of the dissertation a theoretical survey of freight transport models is provided, in order to show the linkage between freight transport and economic activities. A comprehensive analysis of data sources at European, national and regional levels is also provided. In the second part of the dissertation an application to the case of railway intermodal terminals in France is provided, with some comparisons to other European countries. The scope of the analysis is to estimate the potential demand of combined transport, to assess the productivity of intermodal terminals and to evaluate the socio-economic and financial impact of new investments in terminals, also through new project financing schemes (PPPs). The results show a large potential for railway intermodal transport, especially in connection with maritime ports, and low productivity in existing terminals. As a consequence it’s fundamental to concentrate new investments in a few high potential locations, in order to attract private investments and to provide a better use of public funds. The policy implications of this analysis are multiple: it concerns first the railway companies and the infrastructure managers, which should better plan their investments according to commercial needs. It concerns also governments and regional authorities which should better concentrate public funds on optimal terminal locations.

Le montant annuel de la fraude européenne à la carte de paiement se monte à plus d’1,5 milliard d’euros. Cette manne aiguise l’appétit des groupes criminels qui exploitent la moindre faille de la monétique (écosystème de la carte de paiement). Les cinq principaux acteurs de la monétique (porteurs, émetteurs, accepteurs, acquéreurs et systèmes de paiement) s’appuient pourtant sur des systèmes et réseaux normalisés dont la sécurité est encadrée par des standards internationaux contraignants. Néanmoins, la fraude monétique ne cesse de progresser alors que les moyens de lutte (étatiques, collaboratifs ou individuels) restent limités.Après étude de la fraude monétique, cette thèse propose différentes actions (passives,réactives et proactives) visant à améliorer la lutte contre la fraude monétique. D’abord,il convient de mieux connaître la fraude en étudiant la provenance des données volées et plus seulement leur usage. Ensuite l’expertise de ces fraudes doit être améliorée, en développant par exemple une captation du progrès scientifique. Une expertise qui doit être en partie transmise aux enquêteurs afin qu’ils puissent conduire leurs enquêtes. Enquêtes qui peuvent être dynamisées par des opérations réactives associant investigateurs et sachants techniques. Enfin, de manière proactive, les enquêtes et analyses de demain doivent être facilitées par les technologies monétiques conçues aujourd’hui. / Every year, payment card fraud exceeds 1.5 billion euros in Europe. Organised crime groups are exploiting any vulnerability possible to take a piece of this lucrative activity. Even though the five principal entities in the payment card industry (cardholders, issuers,acceptors, acquirers and payment system providers) are implementing binding security measures through out standardized systems and networks, fraud continues to increase. Efforts by the state, industry collaboration, and individuals have been unsuccessful in decreasing criminal advances. Having analysed the elements of payment card fraud, this thesis proposes several actions (passive, reactive and proactive) to help improve the fight against this fraud. First, itis relevant to gain knowledge of the source of the card details and not to focus only on its reuse. Next, forensic assessment has to be improved, for example by developing an increased scientific understanding of the technology. Such an expertise should then be passed on to investigators through effective training and knowledge transfer. Investigations should also be made more dynamic with reactive operations conducted in concert by investigators and technicians. Finally, in an ideal proactive spirit, future investigations and assessments should be oriented and facilitated by studying and influencing current payment card technology developments.

A city's intersections are places or voids where the trajectories, paths and commuter routes of a cities citizens collide. They are points of momentary stasis. At intersections the agents of speed and haste characteristic of the flow of the city are brought to a collective pause. The challenge of this thesis was to bring about an architectural representation of this negotiation between flow and pause. There was a desire to see the commuterscape of Vancouver as a way of allowing different publics and contrasting programmes the opportunity for chance encounters and collisions. This desire led to the design of a building which served as an intersection, sometimes carefully controlled while at others free and open to the random flows of urbanism. The site at the corner of Main and Terminal streets in Vancouver was chosen because it is a place where the di verse social, economic and historical fabrics of the city are intersecting. This site is the busiest at grade intersection in Vancouver where skytrain and bus passengers, car drivers and pedestrians are variously pushed together and pulled apart. Commuter space and commuter movement through that space are generally assumed to be unproductive, uninfected movement through vacuous and empty space. This thesis challenges that view by inserting a building into this commuter space to utilize the potentials for exchange, negotiation and encounter offered by such a space. The building is made up of two very different programs - one containing a series of small performing arts theatres, the other commercial and rentable office space. In between the two, the inbound and outbound skytrain tracks and a public walkway create varying perceptual experiences which mediate between the two different typologies. The public zones of the building are used to link the varied programs together and to create connections to the surrounding park and buildings. / Applied Science, Faculty of / Architecture and Landscape Architecture (SALA), School of / Graduate

<div><p>Parkinson’s disease (PD) is a devastating neurodegenerative disorder that affects 10 million people worldwide and is characterized by pronounced motor symptoms. Dementia with Lewy Bodies (DLB) involves both cognitive and motor deficits and affects ~1 million people in the United States. To date there is no cure for PD or DLB, and current treatments address only a subset of the symptoms that define these diseases. PD and DLB are ‘synucleinopathies’, defined as disorders involving the accumulation in patients’ brains of Lewy bodies. Lewy bodies are cellular inclusions that consist largely of aggregated species of alpha-synuclein (aSyn), a presynaptic protein that exists as both cytosolic and membrane-bound forms. Pathophysiological findings suggest that aggregated aSyn is involved in neurodegeneration in PD and DLB. However, mechanisms by which aSyn forms neurotoxic aggregates, and neurotoxic processes that distinguish different synucleinopathies such as PD and DLB, are poorly understood. To address these gaps, we have (i) designed a protocol to establish a primary cell culture model that can recapitulate key neuropathological features of PD, (ii) examined effects of expressing aSyn variants in a rat model of PD, and (iii) examined the expression profiles of neuroprotective genes in PD and DLB brain specimens.</p><p> </p><p>In the first part of my thesis, I describe the development of an optimized protocol to prepare primary midbrain and cortical cultures from rat embryonic brains for the study of PD and other synucleinopathies. The establishment of cellular models that simulate specific aspects of neuropathology can enable the characterization of molecular perturbations that lead to dopaminergic (DA) neuronal death. Our primary midbrain mixed culture model provides an outstanding opportunity to explore therapeutic strategies to rescue DA neurons from toxicity elicited by a range of PD-related insults. In addition, our primary cortical mixed cultures can be used to model cortical neuropathology in various CNS disorders including synucleinopathies.</p><p> </p><p>A number of mutations in the gene that codes for aSyn are associated with familial, early-onset forms of PD. A major goal of my thesis research is to characterize neurotoxic effects of a recently discovered familial substitution, A53E. This mutant was chosen based on the rationale that the introduction of a negatively charged residue at position 53 could potentially interfere with aSyn-membrane interactions and favor A53E aggregation, as we described for other familial aSyn mutants. For the first time, we have reproduced the neurotoxicity of A53E seen in human patients by expressing the mutant protein in rat midbrain. Rats injected unilaterally in the substantia nigra (SN) with rAAV encoding A53E and another familial mutant, A53T, but not rAAV encoding WT aSyn or a vector-control (‘stuffer’) virus, exhibited a significant motor impairment. Immunohistochemical analysis at 14 weeks after the viral injection revealed that brain sections from aSyn-expressing rats exhibit key features reminiscent of neuropathology in human PD, including nigral dopaminergic neuron loss (confirmed by unbiased stereology), striatal terminal depletion, and aSyn inclusion formation. In addition, it was determined that WT aSyn and the A53E and A53T mutants invaded the non-injected substantia nigra, implying that expressed aSyn protein can spread throughout the brain in the rat rAAV-aSyn model. These results yield insights into the molecular basis for the neurotoxicity of A53E and shed light on a potential role for membrane-induced aSyn aggregation in PD pathogenesis in vivo, thus setting the stage for developing therapies to slow neurodegeneration in the brains of familial and idiopathic PD patients. </p><p> </p><p>aSyn neurotoxicity varies with the expression of neuroprotective proteins, and misfolded aSyn affects cellular functions and gene expression. These observations suggest that differential gene expression patterns can inform us about similarities and differences in pathogenic mechanisms of different synucleinopathy disorders. A third phase of my thesis research was aimed at determining the expression levels of a panel of candidate neuroprotective genes in post-mortem brain samples from DLB and PD patients and age-matched controls (5 individuals in each group). mRNAs encoding the following proteins were quantified via qRT-PCR in homogenates prepared from the frontal cortex and the BA24 region encompassing the cingulate gyrus: DJ-1, a protein with antioxidant and chaperone activities; PGC1α, a master regulator of mitochondrial biogenesis and oxidative metabolism; MsrA, an antioxidant enzyme responsible for repairing oxidatively damaged proteins; and ATP13A2, a lysosomal protein involved in autophagy. In addition to yielding new insights into differential gene expression patterns in cortex versus cingulate gyrus, the data revealed differences in mRNA expression levels in DLB versus non-DLB cortical tissue. Although levels of all four neuroprotective mRNAs were increased (or showed a trend towards being increased) in DLB cortex, Western blot analysis revealed that only the DJ-1 and PGC1α proteins showed a trend towards being up-regulated, whereas levels of ATP13A2 and MsrA were unchanged. These findings suggest that there is a failure to induce cellular antioxidant responses and lysosomal autophagy at the protein level in DLB cortex, and in turn this failure could contribute to neuropathology. Interestingly, analysis of the same panel of neuroprotective genes in PD cortical samples did not show significant differences in mRNA or protein levels compared to control samples, suggesting that different neuroprotective mechanisms are induced in DLB versus PD cortex. These studies shed light on brain-region specific changes in gene expression associated with different synucleinopathy disorders, and they set the stage for developing new diagnostic tests and therapeutic strategies.</p></div><br>

Emerging evidence in both vertebrates and invertebrates is redefining glia as active players in the development and integrity of the nervous system. The formation of functional neuronal circuits requires the precise addition of new synapses. Mounting evidence implicates glial function in synapse remodeling and formation. However, the precise molecular mechanisms governing these functions are poorly understood. My thesis work begins to define the molecular mechanisms by which glia communicate with neurons at the Drosophila neuromuscular junction (NMJ). During development glia play a critical role in remodeling neuronal circuits in the CNS. In order to understand how glia remodel synapses, I manipulated a key component of the glial engulfment machinery, Draper. I found that during normal NMJ growth presynaptic boutons constantly shed membranes or debris. However, a loss of Draper resulted in an accumulation of debris and ghost boutons, which inhibited synaptic growth. I found that glia use the Draper pathway to engulf these excess membranes to sculpt synapses. Surprisingly, I found that muscle cells function as phagocytic cells as well by eliminating immature synaptic ghost boutons. This demonstrates that the combined efforts of glia and muscle are required for the addition of synapses and proper growth. My work establishes that glia play a crucial role in synapse development at the NMJ and suggests that there are other glial-derived molecules that regulate synapse function. I identified one glial derived molecule critical for the development of the NMJ, a TGF-β ligand called Maverick. Presynaptically, Maverick regulates the activation of BMP pathway confirmed by reducing the transcription of the known target gene Trio. Postsynaptically, it regulates the transcription of Glass bottom boat (Gbb) in the muscle suggesting that glia modulate the function of Gbb and consequently the activation of the BMP retrograde pathway at NMJ. Surprisingly, I also found that glial Maverick regulates the transcription of Shaker potassium channel, suggesting that glia potentially could regulate muscle excitability and consequently modulate synaptic transmission. Future work will elucidate such hypothesis. My work has demonstrated two novel roles for glia at the NMJ. First is that glia engulfing activity is important for proper synaptic growth. Second is that the secretion of glial-derived molecules are required to orchestrate synaptic development. This further supports that glia are critical active players in maintaining a functional nervous system.

Les neurones dopaminergiques (DAergiques) de l’aire tegmentaire ventrale (ATV) et de la substance noire compacte (SNc) sont impliqués dans de nombreuses fonctions physiologiques telles que la motivation, la récompense, l’apprentissage ou encore le contrôle du mouvement volontaire. Ces neurones sont également connus pour être perturbés dans plusieurs grandes maladies du cerveau telles que la schizophrénie, les maladies associées aux drogues d’abus ou dans la maladie de Parkinson. Des études in vivo ont démontré que la structure des terminaisons axonales DAergiques pouvait être de type « synaptique » et « non-synaptique ». Ces terminaisons dites « non-synaptiques », dépourvues de toute apposition avec un domaine membranaire postsynaptique, semblent représenter la grande majorité des terminaisons axonales établies par les neurones DAergiques. De façon intéressante, certaines des terminaisons synaptiques ont quant à elles, la capacité de co-libérer du glutamate ou du GABA. D’une façon générale, la formation et le maintien des synapses fait intervenir des protéines d’adhésion cellulaire dont les plus courantes sont les neurexines (Nrxn) et les neuroligines (Nlgn). Au niveau présynaptique, ces molécules d’adhésion interagissent avec des protéines de la zone active qui sont impliquées dans la régulation de l’exocytose. Parmi elles, on retrouve RIM1/2, Piccolo/Bassoon, ELKS ou encore Munc-13. Du côté postsynaptique, ces protéines d’adhésion cellulaire interagissent directement avec les protéines d’échafaudages telles que PSD95 ou Géphyrine. Mes travaux de doctorat ont consisté dans un premier temps à caractériser de façon exhaustive les terminaisons axonales établies par les neurones DAergiques. La proportion et la structure moléculaire des terminaisons synaptiques et non-synaptiques ont ainsi été évaluées. Dans un premier article, via l’utilisation d’un système in vitro, nous avons démontré qu’une minorité des terminaisons DAergiques (20%) était de nature synaptique, une proportion totalement différente lorsque comparée avec les neurones glutamatergique ou GABAergiques, dont les terminaisons synaptiques sont très fortement majoritaires (80%). De façon intéressante, la protéine de ZA Bassoon a été retrouvée majoritairement au sein des terminaisons synaptiques suggérant une différence de structure avec les terminaisons non-synaptiques. Finalement, au niveau du mécanisme de formation des synapses, nous avons mis en évidence que la surexpression de la protéine présynaptique Nrxn-1SS4- dans les neurones DAergiques permet d’augmenter la proportion de terminaisons synaptiques alors que la surexpression de la Nlgn-1AB est, quant à elle, capable d’induire une différentiation présynaptique DAergique. Dans un second article, nous avons voulu investiguer plus en détails le rôle des Nrxn dans la synaptogénèse DAergique. Pour ce faire, nous avons pris avantage d’un modèle animal totalement inédit mais absolument fascinant où nous avons évalué l’impact d’une délétion conditionnelle de l’ensemble des Nrxn sur la connectivité DAergique. Dans cette étude nous avons démontré que la densité de synapses excitatrices et inhibitrices établies par les neurones DAergiques n’était pas affectée chez les souris DAT::NrxnsKO et ce en comparaison des animaux de souche sauvage. Dans un deuxième temps, via des enregistrements électrophysiologiques, nous avons évalué la neurotransmission excitatrice et inhibitrice établie par les neurones DAergiques. Les résultats n’ont pas révélé de changement dans la neurotransmission excitatrice mais ont curieusement révélé un renforcement de l’activité synaptique inhibitrice chez les animaux Nrxn DAT::NrxnsKO et ce par rapport aux animaux du groupe contrôle. Finalement, via la mise en place de tests comportementaux, nous avons pu observer que les animaux DAT::NrxnsKO avaient une capacité d’apprentissage et de locomotion identique aux animaux de souche sauvage, cependant, une stimulation pharmacologique du système DAergique par l’amphétamine a révélé d’une diminution significative de la locomotion chez les souris DAT::NrxnsKO, pouvant refléter une baisse de la neurotransmission DAergique en condition non physiologique. Ces travaux de doctorat amènent pour la première fois une nouvelle vision sur la capacité des neurones DAergiques à établir une arborisation axonale majoritairement non-synaptique. Cette thèse démontre que les neurones DA du mésencéphale ont un programme intrinsèque de développement de leur arborisation axonale qui est différent des neurones GABAergiques du striatum et glutamatergiques du cortex. Aussi, au travers de ces travaux, nous montrons clairement que des protéines aussi fondamentales que les Nrxn et les Nlgn ont un impact limité dans la formation, le maintien et le fonctionnement des synapses établies par les neurones DAergiques. / Dopamine (DA) neurons from the substantia nigra compacta (SNc) and ventral tegmental area (VTA) are key players of the neuronal circuitry regulating movement initiation, reward and learning. Their functioning and survival are also perturbed in diseases such as schizophrenia, drug abuse and Parkinson’s. The axonal connectivity of DA neurons is particularly intriguing due to the hyperdense nature of the axonal arbor of these neurons, containing a very large number of neurotransmitter release sites. Ultrastructural examination of the axon terminals established by DA neurons failed to identify a tight pre- and postsynaptic coupling at most of release sites, giving rise to the concept of non-synaptic terminals and “diffuse” or volume transmission. Furthermore, it is now well established that a subset of terminals established by DA terminals has the capacity to release other neurotransmitters such a glutamate and GABA. A large literature implicates trans-synaptic proteins including neurexins (Nrxns) and neuroligins (Nlgns) in the development of synaptic contacts. In the presynaptic compartment, these cell adhesion molecules interact with active zone proteins like RIM1/2, Bassoon, ELKS and Munc-13 involved in regulating exocytosis. In the postsynaptic compartment, these cell adhesion molecules closely interact with scaffolding proteins like PSD95 or Gephyrin. In this thesis work, we first performed an exhaustive characterization of axon terminals established by DA neurons in primary co-culture system. We evaluated the proportion and the molecular structure of synaptic and non-synaptic terminals established by VTA and SNc DA neurons. In our first article, using and efficient in vitro system, we demonstrated that DA neurons develop a small proportion of synaptic terminals that is strikingly lower compared to glutamatergic and GABAergic neurons. Interestingly, we discovered that the active zone protein Bassoon is mainly expressed in DA terminals that are in contact or in close proximity to a target cell, and less expressed in non-synaptic DA terminals. Finally, we found that overexpression of Nrxn-1SS4- in DA neurons leads to an increase in the proportion of synapses whereas, overexpression of Nlgn-1A+B is able to trigger a DA presynaptic differentiation of DA neurons, suggesting a key role for these transsynaptic proteins in synapse formation by DA neurons. In a second article, we studied more globally the role of Nrxns proteins in the formation of synapses by DA neurons. We took advantage of a recently introduced triple conditional Nrxn mouse line to selectively delete Nrxns in DA neurons and examine the impact of this gene inactivation on the connectivity of DA neurons. In this part we demonstrated that the density of excitatory and inhibitory synapses density established by DA neurons is not affected by the deletion of all Nrxns, in comparison to the wild type group and does not impair the basic development and axonal connectivity of DA neurons at least, in vitro. In a second set of experiments, using patch-clamp recordings, we evaluated the function of excitatory and inhibitory synapses established by DA neurons in the striatum. GABA and glutamate synaptic currents evoked in the striatal medium spiny neurons by optogenetic stimulation of DA neuron axons revealed that glutamate release was unchanged, but identified a strong tendency for enhanced GABA co-release. Furthermore, using fast scan cyclic voltammetry, we found that the loss of Nrxns was associated with impaired DA transmission in the brain of adult mice, revealed by a reduced rate of DA reuptake after electrically-evoked DA release and with impaired amphetamine-induced locomotion. With this thesis, we bring a new perspective on the capacity of DA neurons to develop an axonal arborization that is mainly non-synaptic. With this work, we provide strong evidence arguing that mesencephalic DA neurons are endowed with an intrinsic developmental program leading them to develop an axonal connectivity that is very different from striatal GABA neurons or cortical glutamate neurons. Ours findings suggest that although Nrxns and Nlgns are unlikely to be the main determinants of on the formation of synapses by DA neurons, that are likely to act as key regulators of DA and GABA signaling by these.