This report explores a novel application of the initial state radiation (radiative return) method in an electron-positron collider, to measure the electron-positron annihilation into a neutral pion and a photon  reaction cross section at low energies. The challenge of using ISR events for analysis is due to the combinatorics issue presented by the extra photon(s) in the final state. Through measuring the cross section, access is gained to the time-like electromagnetic transition form factor (TFF) of the neutral pion. This can be used to constrain theoretical models of the hadronic light-by-light scattering contribution to the anomalous magnetic moment of the muon (AMM). The aim of this project was to determine if existing, or expected, data samples at the experiments KLOE-2 in Frascati and BES-III in Beijing could provide competitive results for the time-like TFF slope parameter. The analysis was performed through the construction of an event generator, where events were generated for three different reaction models. Considering the amount of data available at low energies, this study indicates that the ISR approach could be a viable option to enhance the data sample in the low energy region. The most promising experiment for further analysis is here indicated to be KLOE-2. Compared to tabulated values for the form factor slope parameter, the uncertainty retrieved here is roughly on the same order of magnitude or smaller. / I denna rapport behandlas en ny metod för analys av ISR-data från experiment vid elektron-positron-kolliderare, så som KLOE-2 och BES-III. Strålning i form av en eller flera fotoner som strålats ut från elektronen eller positronen innan kollision kallas ISR. Då en foton strålas ut  från initialtillståndet sänks reaktionens nominella energi. Detta möjliggör analys av reaktioner över ett kontinuerligt energispektrum. Utmaningen med ISR analys ligger i kombinatoriken som uppstår då det återfinns ytterligare fotoner i sluttillståndet för reaktionen.I rapporen beskrivs processen elektron-positron-annihilation till en neutral pion och en foton. Denna reaktion är intressant då kunskap om dess reaktionstvärsnitt ger tillgång till den elektromagnetiska formfaktorn för den neutrala pionen. Formfaktorn beskriver hur reaktionen i fråga avviker från en punkt-lik elektromagnetisk växelverkan. Den elektromagnetiska fromfaktorn för den neutrala pionen är i sin tur en viktig del i beräkningarna för det hadroniska bidraget till myonens anomala magnetiska moment (AMM). Eftersom AMM är experimentellt uppmätt till mycket god noggrannhet kan jämförelser med teoretiska modeller göras med hög precision.  Vid låg reaktionsenergi kan formfaktorn beskrivas med endast en parameter, lutningsparametern. Från Monte Carlo genererad ISR-data har i denna rapport lutningsparametern bestämts med noggrannhet som är likvärdig eller bättre än tabulerade värden, beroende på mängd analyserad data samt val av analysmetod.

Dans un contexte de crise économique et financière, de crise sociale via le dumping social renforcé par la mondialisation, et de crise environnementale engendrée par la raréfaction des ressources naturelles et la pollution de l’environnement, l’essor du développement durable et de la Responsabilité Sociale d’Entreprise (RSE) ainsi que de l’analyse extra-financière devraient participer à un processus de création d’innovations au sens de Schumpeter avec l’émergence de technologiques environnementales (Green Tech), et de nouveaux modèles économiques sociaux (Base of the Pyramid et Social Business,) et environnementaux (Économie circulaire, Cradle-to-cradle et Économie de fonctionnalité), sources de compétitivité selon Michael Porter. Ce processus de création d’innovation génère, selon la théorie Schumpetérienne, une destruction des situations préétablies. Au-delà du débat sur la performance des fonds ISR, les Investissements Socialement Responsables jouent un rôle variable dans le développement d’un nouveau cycle économique, selon que la gestion des fonds ISR relève d’une démarche active ou passive. Le renforcement de l’analyse environnementale, sociale et de gouvernance (ESG) participe au développement et à l’enrichissement de l’information extra-financière, ainsi qu’à la valorisation d’un choix social, environnemental et de gouvernance d’entreprise par les investisseurs. / In a context of economic, financial, social crisis through social dumping reinforced by globalization and environmental crisis by the scarcity of natural resources and pollution of the environment, the boom of sustainable development, corporate social responsibility (CSR) and extra-financial analysis should be involved in a process of creating innovations according to Schumpeter theory with the emergence of environmental technology (green tech), and new social models (Buddhist economy, base of the pyramid and social business) and environmental models (circular Economy, cradle-to-cradle and functional economy), source of competitiveness according to Michael Porter. This process of creating innovations generates a destruction of established situations according to the Schumpeterian theory. Beyond the debate on the performance of SRI funds, socially responsible investments have a varying role in the development of this new economic wave according to the management of SRI funds is active or passive. Therefore, the strengthening of the ESG analyses helps the development and enrichment of extra-financial information, as well as the promotion of a social choice, environmental and corporate governance by investors.

Indiana University-Purdue University Indianapolis (IUPUI) / The unfolded protein response (UPR) is important for cell adaptation to accumulation of unfolded proteins in the endoplasmic reticulum (ER). A central UPR sensor of ER stress is PKR- like ER Kinase (PERK), which phosphorylates eIF2 to reduce global translation and help mitigate ER stress. While this is a survival mechanism that serves to save the cell from catastrophic events during ER stress, PERK can also be activated in cancer cells due to genetic changes and exposure to stresses inherent in the tumor micro-environment. Published reports have indicated that PERK is activated in cancer cells in response to hypoxia, nutrient deprivation, matrix detachment, and increased protein load by oncogene activation to facilitate cell survival. The UPR features PERK and another ER stress sensory protein, IRE1α, which also regulates the dynamic assembly of the actin cytoskeleton; loss of either PERK or IRE1α functions decrease cell migration activity. We hypothesized that PERK is required for anchorage-independent survival of the cancer cell line HCT116 and that PERK is essential for cell migration. Consistent with these premises, inhibition of PERK using pharmacological inhibitors GSK2656157 and LY-4 in suspended cells showed reduced growth. Furthermore, PERK-deficient cells showed reduced migration in transwell migration assays as compared to their wild type counterpart. These results suggest that PERK facilitates anchorage-independent growth of cancer cells and cell migration.

In the so-called induced systemic resistance phenomenon (ISR), some non pathogenic rhizobacteria are able to stimulate defence mechanisms in the host plant thereby rendering it less susceptible to subsequent phytopathogen attack. This immunization process is initiated into the plant following the perception of elicitors (or determinants) produced by the beneficial microorganism. Previous studies performed in our laboratory have demonstrated the ability of Pseudomonas putida strain BTP1 and Bacillus subtilis strain S499 (or M4) at triggering ISR. By using these two rhizobacteria, the global objective of this thesis is to contribute to a better understanding of this molecular dialogue between ISR-inducing bacteria and plant cells. Our first researches with BTP1 led to the isolation, as an elicitor, of a new compound produced by Pseudomonas. It was purified from bacterial culture supernatant and identified as a benzylamine core alkylated with two methyl and one tetradecyl groups, conferring its hydrophobic properties. On the basis of this structure, the BTP1 determinant was called NABD, for N-Alkylated Benzylamine Derivative. By testing the pure molecule or mutant strains altered in its production, we have shown that NABD was mainly responsible for ISR-activity of the BTP1 strain on bean and cucumber while in tomato, another unidentified compound could also be involved. In the case of Bacillus subtilis S499, we used similar approaches to demonstrate for the first time that the lipopeptides surfactin and fengycin may act as elicitors to stimulate systemic resistance, thereby attributing them a new role in the biocontrol of plant diseases. Structure/activity studies have revealed the implication of the benzylamine aromatic core in the biological activity of NABD. In the case of surfactin, reduced activity of some homologues indicates that its perception is dictated by structural clues such as the length of the acyl moiety and the presence of charges in the cyclic peptide part. Also in support to their involvement in ISR triggering, significant quantities of NABD and lipopeptides were recovered from the rhizosphere of bacterized plants. The influence of some physiological and physico-chemical factors on NABD production by BTP1 was further investigated in in vitro experiments. Our results show that the molecule is more efficiently produced at low cell growth rate and in the presence of amino acids in the medium but is negatively iron-regulated. Other abiotic factors, such as low oxygen concentration or low pH do not have drastic effects on NABD biosynthesis by the strain. Globally, with regard to specific conditions that the strain undergoes in the rhizosphere environment, it supposes that the nutritional/physiological state of BTP1 cells growing on plant roots is compatible with an effective production of the elicitor. Plant responses induced following root treatment with Bacillus subtilis S499 have also been investigated. Working on whole plants, it first revealed an increase in enzyme activities of the oxylipin pathway (lipoxygenase (LOX) and lipid-hydroperoxydase) after infection. Further investigations were conducted on cultured tobacco cells and we have shown the induction of some early events, such as extracellular pH alkalinization, reactive oxygen species production, defence enzyme stimulation (LOX and phenylalanine ammonia lyase (PAL), and accumulation of some phenolics from the phenylpropanoid pathway. These experimentations performed with Bacillus lipopeptides are the first conducted with ISR-specific elicitors and led to the characterization of early events that can also be triggered by pathogen associated molecules. It is still not clear whether bacterial LPs are recognized by plant cells via specific receptors but the amphiphilic and detergent properties of surfactin strongly suggest that these LPs can interact via a less specific mechanism based on some limited destabilization of the membrane structure. In conclusion, NABD and lipopeptides studied in this thesis enlarge the range of elicitors from non pathogenic bacteria isolated to date, and may be considered as members of a new class of ISR-inducing compounds of amphiphilic nature./ Lors du phénomène appelé « résistance systémique induite » (ISR), des rhizobactéries non pathogènes peuvent conférer à la plante un certain degré de protection à des attaques ultérieures par un phytopathogène via la stimulation de mécanismes de défense systémiques. Cette « immunité » sinitie suite à la perception par la plante de molécules dites élicitrices produites par le microorganisme bénéfique. Lobjectif de cette thèse est de contribuer à la caractérisation de ce dialogue moléculaire en se basant sur des études antérieures poursuivies au laboratoire qui ont mis en évidence la capacité des souches Pseudomonas putida BTP1 et Bacillus subtilis S499 (aussi dénommée M4) à induire lISR chez leur hôte végétal. La première partie des recherches sur BTP1 a permis disoler en tant quéliciteur un nouveau type de composé produit par les Pseudomonas. Cet éliciteur a été isolé à partir de surnageant de culture de la bactérie et est constitué dun noyau benzylamine dont lazote est alkylé par deux groupements méthyle et un groupement tétradécyle, responsables de lhydrophobicité relative de la molécule. Sur cette base, ce métabolite a été dénommé NABD (N-alkylated benzylamine derivative). Grâce au traitement des plantes avec le composé purifié ou via lutilisation de mutants altérés dans sa production, nous avons démontré que le NABD était responsable de lessentiel de lactivité ISR de BTP1 sur le haricot et le concombre. Dans le cas de la tomate par contre, il semble quil ne soit pas le seul éliciteur impliqué. En ce qui concerne Bacillus subtilis S499, en utilisant des approches similaires, nous avons pour la première fois montré limplication de deux lipopeptides, la surfactine et la fengycine, comme agents stimulateurs de lISR, permettant ainsi de leur attribuer un nouveau rôle dans le contrôle biologique des maladies des plantes par Bacillus. Une étude de la relation structure/activité a été entamée et a révélé un rôle du noyau aromatique dans létablissement de la résistance systémique par le NABD. Pour la surfactine, limportance de la longueur de la chaîne alkylée ainsi que la présence des charges sur les acides aminés suggèrent que son activité élicitrice soit liée à ses propriétés amphiphiles. La détection en quantités significatives des deux types déliciteurs dans la rhizosphère des plants traités par les bactéries est également en faveur de leur rôle biologique. Dans le cas de BTP1, nous avons étudié linfluence de certains paramètres physiologiques, nutritionnels et physico-chimiques sur la production du NABD. Les résultats montrent que la production du NABD est dépendante de la présence dacides aminés dans le milieu, quelle est effective à un taux de croissance faible du microorganisme, quelle est négativement influencée par le fer mais quelle nest pas inhibée par une restriction en oxygène dissous disponible ou par une acidification du milieu. Globalement, ces données suggèrent que les conditions physico-chimiques dictant létat physiologique des cellules bactériennes in situ peuvent être propices à une synthèse effective de léliciteur au niveau des racines. Des recherches sur les réponses induites chez lhôte lors de son interaction avec S499 ont été initiées et montrent une nette augmentation dactivités enzymatiques de la voie des oxylipines (activités lipoxygénase (LOX) et lipide hydroperoxydase) dans les feuilles après infection. Une exploration plus approfondie sur suspensions de cellules de tabac en culture avec la surfactine a montré linduction de plusieurs autres mécanismes précoces de défenses, comme une alcalinisation du milieu extracellulaire, la production despèces oxydantes, lactivation denzymes de défense telles que LOX et phenylalanine ammonia lyase (PAL), et une possible réorientation de la voie des phénylpropanoïdes. Ces expérimentations menées avec les lipopeptides de Bacillus sont parmi les premières à être réalisées avec des éliciteurs spécifiques de lISR. Elles ont abouti à la caractérisation de plusieurs réponses précoces dont certaines sont aussi induites par des molécules isolées dagents pathogènes. Les lipopeptides pourraient ainsi agir en stressant les cellules de lhôte via une perturbation temporaire de la membrane externe facilitée par leur propriété amphiphile. Limplication de récepteurs dans la reconnaissance des éliciteurs de BTP1 et S499 ne peut cependant pas être exclue. En conclusion, les lipopeptides et le NABD élargissent la gamme des éliciteurs bactériens de lISR isolés jusquà présent et peuvent être considérés comme appartenant à une nouvelle classe dimmuno-stimulateurs des plantes comprenant des molécules amphiphiles.

Pour lutter contre les nuisibles des cultures (herbivores et pathogènes), de nouvelles voies ont été explorées et en particulier la lutte biologique. Utilisé la nature et ses organismes pour réguler les populations de pathogènes, tel est le but de la lutte biologique aussi appelé biocontrôle. Parmi les organismes couramment retrouvés dans le biocontrôle se trouve les micro-organismes, que cela soit des champignons ou des bactéries. Ces micro-organismes possèdent des capacités très intéressante pour des agriculteurs et agronomes. En effet, des études ont montré qu’ils étaient capables d’interagir avec les plantes pour permettre une meilleure croissance et santé de celle-ci. Alors, dans cette thèse, nous nous sommes intéressés aux bactéries pour trouver des méthodes de luttes alternatives à Fusarium graminearum, un pathogène des céréales responsables de fortes pertes de rendements, en particulier grâce à la production de mycotoxines qui va rendre les grains impropres à la consommation humaine et animales. Par l’intermédiaire d’une approche original consistant à garder des souches non-inhibitrice in vitro pour des tests in planta, nous avons pu montrer les limites de la sélection in vitro. Grâce à l’exploration métaboliques d’une souche particulièrement efficace, nous avons aussi pu mettre en évidence de potentiels nouvelles molécules antifongiques. Par l’intermédiaire d’une souche modèle, nous avons explorer les mécanismes de la mise en place d’une résistance systémique chez le blé induite par les bactéries. Et enfin, nous avons exploré le potentiel des combinaisons de bactéries dans la protection du blé qui semble représenter un vrai futur dans le monde du biocontrôle. Les travaux effectués s’inscrivent dans les besoins de nouvelles ressources pour limiter l’utilisation des pesticides, mais aussi dans un besoin de mieux comprendre les interactions tripartite entre blé, pathogène et bactéries bénéfiques / To combat pests of crops (herbivores and pathogens) new pathways have been explored, in particular biological control. Used the nature and its organisms to regulate the populations of pathogens, that is the goal of the biological fight also called biocontrol. Among the organisms commonly found in biocontrol are micro-organisms, be they fungi or bacteria. These microorganisms have very interesting capabilities for farmers and agronomists. Indeed, studies have shown that they are able to interact with plants to allow a better growth and health of it.Then, in this thesis, we were interested in bacteria to find alternative methods of struggle with Fusarium graminearum, a pathogen of cereals responsible for high yield losses, especially thanks to the production of mycotoxins that will make the seeds unfit for human and animal consumption.Through an original approach of keeping noninhibitory strains in vitro for in planta tests, we have been able to show the limitations of in vitro selection. Thanks to the metabolic exploration of a particularly efficient strain, we have also been able to highlight potential new antifungal molecules. Through a model strain, we explored the mechanisms of the establishment of systemic resistance in wheat induced by bacteria. And finally, we have explored the potential of bacterial combinations in wheat protection that seems to represent a real future in the world of biocontrol.The work done is in line with the needs of new resources to limit the use of pesticides, but also in a need to better understand the tripartite interactions between wheat, pathogen and beneficial bacteria

Submitted by PPG Biologia Celular e Molecular (bcm@pucrs.br) on 2018-03-15T13:05:33Z No. of bitstreams: 1 PATRICIA_FERNANDA_DASILVA_VILCHES_DIS.pdf: 1829625 bytes, checksum: d4b53df7fed69d5202d5bafec96aaa13 (MD5) / Approved for entry into archive by Tatiana Lopes (tatiana.lopes@pucrs.br) on 2018-03-23T12:17:26Z (GMT) No. of bitstreams: 1 PATRICIA_FERNANDA_DASILVA_VILCHES_DIS.pdf: 1829625 bytes, checksum: d4b53df7fed69d5202d5bafec96aaa13 (MD5) / Made available in DSpace on 2018-03-23T12:22:01Z (GMT). No. of bitstreams: 1 PATRICIA_FERNANDA_DASILVA_VILCHES_DIS.pdf: 1829625 bytes, checksum: d4b53df7fed69d5202d5bafec96aaa13 (MD5) Previous issue date: 2017-03-30 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Potatoes (Solanum tuberosum L.) are the third most consumed crop in the world, after rice and wheat. Among the diseases affecting potato, the blackleg and tuber soft rot, caused by phytobacteria Pectobacterium spp., lead to significant losses in the yield crop. Several studies have been exploring the use of plant defense inducers as a strategy to control plant diseases. The use of plant growth-promoting rhizobacteria (PGPR) in agriculture can lead to plant growth and enhancement of plant defense through the promotion of induced systemic resistance (ISR). However, the mechanisms involved in promoting ISR are still poorly understood. This study aimed to screen rhizobacteria of the genus Streptomyces with capacity to promote plant growth and induce Solanum tuberosum innate immunity. To achieve these objectives, we evaluated: i) the ability of Streptomyces isolates to produce auxin (3-indoleacetic acid), ACC deaminase (1-aminocyclopropane-1-carboxylic acid deaminase) and siderophores; ii) their capacity to promote the growth of potato plants; iii) the induction of resistance in potato plants challenged with Pectobacterium carotovorum subsp. brasiliensis and iv) the expression of genes related to defense pathways in S. tuberosum, promoted by Streptomyces and P. carotovorum. Results indicated that the CLV163 isolate presents PGPR features, such as high auxin and siderophores production, and promoted plant defense against P. carotovorum. Although CLV145 showed the highest auxin and siderophores production, it reduced the shoot dry mass and was inefficient in promoting plant defense. Moreover, the ability of Streptomyces in producing ACC deaminase was not critical for promoting plant growth. The CLV163 isolate induced a priming state in potato plants that has occurred through the activation of the AS and ET pathways, and its interaction with S. tuberosum plants did not impair the plant growth. / A batata (Solanum tuberosum L.) ? a terceira cultura agr?cola mais consumida no mundo, ficando atr?s somente do arroz e do trigo. Dentre as diversas doen?as que afetam esta cultura, a canela-preta e a podrid?o-mole, causadas pela fitobact?ria Pectobacterium spp., levam a importantes perdas na produ??o. Neste contexto, v?rios trabalhos v?m explorando o uso de indutores da defesa vegetal como estrat?gia para o controle de doen?as. O uso de rizobact?rias promotoras do crescimento vegetal (PGPR) na agricultura pode promover tanto o crescimento quanto o aumento da defesa das plantas atrav?s da indu??o da resist?ncia sist?mica induzida (ISR). Contudo, ainda s?o pouco conhecidos os mecanismos envolvidos na promo??o da ISR. Este estudo visou selecionar rizobact?rias do g?nero Streptomyces com caracter?sticas de promotoras de crescimento e indutoras da imunidade inata de Solanum tuberosum. Para tanto, foram avaliadas: i) a capacidade de isolados de Streptomyces produzirem auxina (?cido 3- indolac?tico), ACC desaminase (?cido 1-aminociclopropano-1-carbox?lico desaminase) e sider?foros; ii) a capacidade destas rizobact?rias em promover o crescimento das plantas; iii) a promo??o da resist?ncia em plantas de batata desafiadas com Pectobacterium carotovorum subsp. brasiliensis e iv) a express?o de genes relacionados a vias de sinaliza??o de respostas de defesa em S. tuberosum, promovida por Streptomyces sp e a fitobact?ria P. carotovorum. Os resultados indicam que o isolado CLV163 apresenta caracter?sticas de PGPR, sendo capaz de produzir auxina e sider?foros, al?m de promover o aumento da resist?ncia das plantas contra P. carotovorum. Contudo, a rizobact?ria CLV145, com a maior produ??o de auxina e sider?foros, causou a diminui??o da mat?ria seca de parte a?rea e n?o promoveu a defesa das plantas. A capacidade dos Streptomyces em produzirem ACC desaminase n?o foi determinante para a promo??o de crescimento vegetal. O isolado CLV163 induziu um estado de priming nas plantas de S. tuberosum L. atrav?s da ativa??o das vias do AS e ET e a sua intera??o com as plantas de batata n?o comprometeu o crescimento vegetal.

Le choc septique est défini par une hypotension persistante malgré un remplissage vasculaire adéquat en présence d’une réponse inflammatoire systémique suite à une infection. Il est responsable de 10% des admissions en réanimation et malgré des progrès thérapeutiques constants, la mortalité liée au sepsis varie entre 30% et 60% dans les cas de choc septique. Dans 50% des cas, le choc septique est associé à une insuffisance surrénale relative ce qui diminue la probabilité de survie des patients. Les patients sont alors traités avec de l’hydrocortisone et de la fludrocortisone, mais ce traitement est très controversé. Pour la première fois, nous avons pu mettre au point et valider une technique de quantification de la fludrocortisone plasmatique après une prise de 50 μg. Cette technique a pu ensuite être utilisée pour l’obtention de l’étude pharmacocinétique/pharmacodynamique de la fludrocortisone chez le volontaire sain et le patient septique avec insuffisance surrénale relative. Enfin, nous avons étudié la distribution et l’élimination de cette molécule chez la souris saine et deux modèles de sepsis. Les paramètres pharmacocinétiques montrent que la demi-vie de la fludrocortisone est d’environ 1 h, avec un délai d’absorption d’environ 50 minutes. Nos travaux ont permis de mettre en évidence qu’il existe deux populations de patients : les absorbants et les non-absorbants la fludrocortisone, qui représentent 30 % des patients testés, ce qui pourrait être à l’origine de la controverse sur les effets bénéfiques de cette molécule sur la survie des patients. Cependant nous n’avons pu mettre en évidence aucun effet hémodynamique de cette molécule sur les patients septiques. / The septic shock is defined by persistent hypotension despite fluid resuscitation with systemic inflammation due to infection. This is the cause of 10% of the admission in intensive care unit. Despite steady progress in therapeutics, the mortality of patients with sepsis varies between 30% to 60% for a septic shock. In 50%, the septic shock is associated to relative adrenal insufficiency which decrease survival probability of the patients. The patients receive hydrocortisone and fludrocortisone but this treatment is still controversial. For the first time, we developped and validated a quantification method of low concentration fludrocortisone in plasma. This method were used for the pharmacokinetic/pharmacodynamic study of fludrocortisone in healthy volunteers and patients with septic shock associated with relative adrenal insufficiency. Then we studied the distribution and elimination of this molecule in two mice models of sepsis. The pharmacokinetic parameters show that the half-life of fludrocortisone is about 1h and the delay of absorption is about 50min. Our study shows two groups of patients : absorbent patients and non-absorbent patients which have no detectable fludrocortisone concentrations in plasma. This population represents 30% of the population. This could be the reason of the controversial results. No hemodynamic effetc were found in patients with septic shock due to fludrocortisone after low-dosage administration.

The Integrated Stress Response (ISR) is a conserved eukaryotic translational and transcriptional program implicated in mammalian metabolism, memory and immunity. Although mainly considered to be a protective mechanism, prolonged and severe ISR can result in cell death. The ISR is activated by diverse stress pathways converged on phosphorylation of the alpha subunit of eukaryotic translation initiation factor 2 (eIF2) that inhibits the guanine nucleotide exchange activity of its partner eIF2B and attenuates overall rates of protein synthesis. Numerous mutations in eIF2B are linked to a fatal neurodegenerative disease of vanishing white matter. A new chemical inhibitor of the ISR (ISRIB), a bis-O-arylglycolamide, can reverse the attenuation of mRNA translation by phosphorylated eIF2 protecting mice from prion-induced neurodegeneration and traumatic brain injury. The work presented in this dissertation describes identification of mammalian eIF2B as a cellular target of ISRIB by implementing biochemical, biophysical, structural and chemogenetic methods. The herein reported cryo-electron microscopy-based structure of eIF2B uncovers a novel allosteric site on the translation factor capturing the ISRIB-binding pocket at the interface between its β and δ regulatory subunits. The extensive CRISPR/ Cas9-based screen for ISRIB-resistant and analogue-sensitive phenotypes revealed residues on the eIF2B dimer interface important for ISRIB binding. Based on the results reported in this dissertation along with the similar findings of others the potential molecular basis of ISRIB action, and its implication for the regulation of eIF2B's activity is broadly discussed. The identification of the ISRIB binding pocket away from the known interaction sites between eIF2B and eIF2 is also put into the context of a possible molecular mechanism of eIF2B's guanine exchange inhibition by phosphorylated eIF2. The work described in this dissertation provides new insight into the translational regulation and points to the importance of fine-tuning the activity of translation factors by small chemical molecules.

Les smectites sont présentent dans de nombreux environnements de surface et sub-surface au sein desquels elles jouent un rôle prépondérant dans la mobilité des cations majeurs et traces de part leurs capacités d’adsorption. En contexte de réhabilitation de sites miniers exploités par lixiviation acide, ces smectites jouent un rôle dans la remontée du pH des eaux ainsi que dans l’immobilisation des éléments solubilisés. La nature des argiles présentent dans les sables non consolidés d’un aquifère exploité a donc été étudié. La présence de smectites du type beidellite (charge tétraédrique) a été mise en évidence. Cependant, il existe peu d’études sur les propriétés de la beidellite, la majorité portant sur la montmorillonite (charge octaédrique). Un modèle d’échange pour 5 cations majeurs des eaux naturelles (Na, K, Ca, Mg, H) et un élément trace (226Ra) a donc été réalisé sur une beidellite de référence. Les vitesses de dissolution et les mécanismes à l’interface solide/solution en milieu acide ont ensuite été étudiés, validant l’application du modèle d’échange à bas pH. Des effets dus à l’organisation des particules en suspension (texture/agrégation) ont aussi été mis en évidence sur les propriétés d’échange et de dissolution. Lors de ces travaux, l’accent a été mis sur l’impact de la cristallochimie sur la réactivité des smectites par comparaison entre les propriétés de la beidellite et de la montmorillonite. Les résultats indiquent que la cristallochimie des smectites a un impact significatif sur leur comportement, ce paramètre pourrait ainsi être utilisé afin d’alimenter les modèles de transport réactif prenant en compte les propriétés des smectites. / Swelling clay minerals, in particular smectites, are present in many surface and subsurface environments in which they have a major impact on the mobility of major cations and trace elements due to their adsorption capacity. In context of remediation of mining environments operated by acid leaching, these smectites can act as pH buffer and play a role in the immobilization of soluble elements. The type of clay minerals present in the poorly consolidated sands of an aquifer leached by acid solutions was studied. The presence of beidellite type smectites (di-octahedral, tetrahedral charge) was evidenced. However, few studies exist on the ion exchange properties or the dissolution of beidellite, as most of them deal with montmorillonite properties (di-octahedral, octahedral charge). Then, an ion-exchange model involving 5 major cations of natural waters (Na, K, Ca, Mg, H) and one trace element (226Ra) was proposed for a reference beidellite. Dissolution rates and interfacial mechanisms in acidic solutions were investigated in order to check for the validity the ion-exchange model at low pH. Moreover, effects due to the texture/aggregation of particles in suspension were evidenced on the ion-exchange and dissolution properties. This study was focused on the impact of the crystal chemistry on reactive property of the smectites, by comparison of the properties of beidellite with those of montmorillonitic minerals. Results indicate that smectites crystal chemistry has a significant impact on their properties, and such parameter could be considered in reactive transport models when they take into account cation exchange and dissolution properties of smectites.

Made available in DSpace on 2014-08-20T14:07:34Z (GMT). No. of bitstreams: 1 dissertacao_jaqueline_tavares_schafer.pdf: 2389820 bytes, checksum: 6ebde337718d550322c67052472113ac (MD5) Previous issue date: 2011-03-03 / The rice crop is subject to the occurrence of various diseases that cause yield losses of crops. Currently is seeking alternative ways to control these diseases, and biocontrol a viable possibility. The aim of this study was to compare the control of brown spot and leaf scald of rice provided by rhizobacteria isolated and combined, their impact on grain production, as well as the involvement of induced resistance associated with the activity of catalases and peroxidases. We used the DFs185 rhizobacteria (Pseudomonas synxantha) DFs223 (P. fluorescens), DFs306 (not identified), and DFs416 DFs418 (Bacillus sp.). And some combinations of these. Rice seeds of El Paso 144L were immersed in suspensions (A540 = 0.5) for each of the bacterial treatments and agitated for 30'/10°C. Seeds immersed in saline and saline plus fungicide were used as control. The experiment was conducted in a greenhouse, with assessment of disease severity in two separate trials. The first was conducted by the production and second, plants were collected at three different times to check the enzyme activity (0 h before inoculation, 24 and 168 h after). The experimental design was completely randomized. In general, the bacterial treatments were able to control both diseases, except DFs306 not provided effective control of brown spot in the first trial. In plants inoculated with Bipolaris oryzae, no treatment was able to increase production of grains or grains with lower intensity of staining. Already in plants inoculated with Gerlachia oryzae, all treatments resulted in increase of at least one variable related to production. In general, it was possible to associate the participation of enzymes evaluated the control provided by some treatments. Thus, it is believed that the bacterial treatments, individual and combined, have the potential to control brown spot and leaf scald and ability to induce resistance by altering the activity of catalases and peroxidases. / A cultura do arroz irrigado está sujeita à ocorrência de várias doenças que provocam perdas na produtividade das lavouras. Atualmente buscam-se alternativas para o controle destas doenças, sendo o biocontrole uma possibilidade viável. O objetivo deste trabalho foi de comparar o controle da mancha parda e da escaldadura do arroz proporcionado por rizobactérias isoladas e em combinações, seu impacto sobre a produção de grãos, bem como o envolvimento da indução de resistência associado à atividade de catalases e peroxidases. Utilizaram-se as rizobactérias DFs185 (Pseudomonas synxantha), DFs223 (P. fluorescens), DFs306 (não identificado), DFs416 e DFs418 (Bacillus sp.), e algumas combinações destas. Sementes de arroz da cultivar El Paso 144L foram imersas nas suspensões (A540=0,5) de cada um dos tratamentos bacterianos e agitados por 30 /10°C. Sementes imersas somente em solução salina e em salina mais fungicida foram usadas como testemunha. O experimento foi conduzido em casa de vegetação, com avaliação da severidade das doenças, em dois ensaios distintos. O primeiro foi conduzido até a produção e o segundo, as plantas foram coletadas em três diferentes tempos para verificar a atividade enzimática (0 h antes da inoculação, 24 e 168 h após). O delineamento experimental foi inteiramente casualizado. De modo geral, os tratamentos bacterianos foram capazes de controlar ambas as doenças, exceto DFs306 que não proporcionou controle efetivo da mancha parda no primeiro ensaio. Nas plantas inoculadas com Bipolaris oryzae, nenhum tratamento foi capaz de aumentar a produção de grãos ou grãos com menor intensidade de manchas. Já nas plantas inoculadas com Gerlachia oryzae, todos os tratamentos avaliados resultaram em aumento de pelo menos uma variável relacionada à produção. Em geral, foi possível associar a participação das enzimas avaliadas ao controle proporcionado por alguns tratamentos. Assim, acredita-se que os tratamentos bacterianos, individuais e combinados, possuem potencial de controle da mancha parda e da escaldadura e capacidade para induzir resistência pela alteração da atividade de catalases e peroxidases.