As restrições impostas a utilização de antibióticos como aditivos alimentares para bovinos têm estimulado a busca por tecnologias alternativas. Nesse sentido, foram conduzidos dois experimentos com o objetivo de avaliar o efeito de diferentes aditivos alimentares orgânicos e antibióticos sobre o desempenho, metabolismo ruminal, características de carcaça e qualidade da carne de bovinos Nelore confinados recebendo dietas com alta proporção de concentrado. As dietas continham 85% de concentrado e 15% de volumoso e os aditivos correspondentes aos tratamentos, sendo eles: 1) Aditivo orgânico (Fator P®) (A0), 2) Aditivo orgânico + Monensina sódica (AO+M), 3) Aditivo orgânico + enzimas amilolíticas (AO+E), 4) Monensina sódica + Virginiamicia (M+V). No experimento 1, 45 tourinhos da raça Nelore com 24 meses de idade e peso médio inicial de 373±32 kg, foram alojados em 4 baias coletivas equipadas com portões eletrônicos, para controle individual da alimentação, em um delineamento em blocos casualizados (peso inicial). Durante o confinamento foram analisadas as características de desempenho e de carcaça por ultrassonografia. Após 88 dias de confinamento os animais foram abatidos e analisadas características de carcaça, qualidade da carne e teste sensorial de aceitação pelo consumidor. No experimento 2 foram utilizados 8 novilhos da raça Nelore, com cânulas ruminais em um delineamento em quadrado latino 4 x 4 duplicado, com quatro tratamentos e 4 períodos de 21 dias, sendo realizadas análises de degradabilidade, pH ruminal e ácidos graxos de cadeia curta (AGCC). As características de desempenho, bem como as variáveis de degradabilidade ruminal não foram influenciadas pelos diferentes aditivos. O tratamento M+V apresentou maior pH ruminal (P<0,05), enquanto os tratamentos AO+M e AO+E apresentaram maiores concentrações de ácido acético e do total de AGCC (P<0,05). Maiores concentrações de ácido butírico foram encontrados nos tratamentos AO e AO+M (P<0,05). Os tratamentos não influenciaram o peso de carcaça quente, rendimento de carcaça, área de olho de lombo, pH da carcaça 24h após o abate, cor e lipídios totais. O tratamento M+V apresentou maior EGSU enquanto o tratamento AO+E apresentou menor EGPU (P<0,05) em relação aos demais. O tratamento AO apresentou menor perda por cocção em relação aos demais (P<0,05), sendo observado maiores escores de suculência para os tratamentos AO, AO+M e AO+E (P<0,05) e maiores escores de textura e qualidade global para os tratamentos AO e AO+M (P<0,05). O uso de aditivos orgânicos pode ser uma alternativa ao uso dos antibióticos tradicionais na terminação de bovinos confinados com dietas com alta proporção de concentrado, sem alterar os níveis produtivos, sugerindo possível melhora na aceitação pelo consumidor. / The restrictions applied for the use of antibiotics with feed additives for cattle have stimulated the search for alternative technologies. In this sense, two experiments were conducted to evaluate the effect of different organic food additives and antibiotics on performance, ruminal metabolism, carcass characteristics and meat quality of feedlot Nellore cattle fed high concentrate diet. The diets contained 85% of concentrate and 15% of corn silage and additives corresponding to each treatment: 1) Organic additive (AO), 2) Organic additive + Monensin sodium (AO+M), 3) Organic additive + amylolytic enzymes (AO+E), 4) Monensin sodium + Virginiamycin (M+V). In the experiment 1, 45 Nellore steers with 24 months of age and initial body weight of 373 ± 32 kg were allotted in four collective pens equipped with electronic gates for individual control of feeding in a randomized complete block design. During the feedlot, animal performance and carcass characteristics were analyzed by ultrasonography. After 88 days of feedlot, the steers were slaughtered and carcass characteristics, meat quality and sensorial acceptance test by the consumer were analyzed. In the experiment 2, eight Nellore steers with ruminal cannulas were used in a 4 x 4 duplicate Latin square design, with four treatments and four periods of 21 days. Degradability, ruminal pH and short chain fatty acids (AGCC) were evaluated. The different additives did not influence the performance characteristics, as well as, the ruminal degradability variables. The M+V treatment had higher ruminal pH (P<0.05), whereas AO+M and AO+E treatments had higher concentrations of acetic acid and total AGCC (P<0.05). Higher concentrations of butyric acid were found in AO and AO + M treatments (P<0.05). The treatments did not influence hot carcass weight, carcass yield, ribeye area, carcass pH 24h after slaughter, color nor total lipids. The M+V treatment showed higher EGSU while the AO + E treatment presented lower EGPU (P <0.05) when compared with others. The AO treatment presented lower cooking loss (P<0.05), with higher succulence scores for AO, AO+M and AO+E treatments (P<0.05), and higher texture and quality scores for AO and AO+M treatments (P<0.05). The use of organic additives can be an alternative to the use of traditional antibiotics in finishing cattle fed high concentrate diets without affecting the production levels, suggesting possible improvement in consumer acceptance.

Terminaison de la transcription. Rho se fixe aux transcrits naissants au niveau d’un site Rut (Rhoutilization) libre à partir duquel il transloque le long de l’ARN (5’→3’) de façon ATP-dépendante pour rattraper le complexe d’élongation de la transcription et induire la dissociation de celui-ci. Il est généralement admis que les sites de fixation de Rho présentent une richesse en Cytosines et une pauvreté en Guanines, ainsi qu’une relative pauvreté en structures secondaires. Les études génomiques ou transcriptomiques n’ont pas dégagé d’éléments consensus ou de règles permettant de prédire les sites de terminaison Rho-dépendants. En combinant approches biochimiques et bioinformatiques, j’ai tenté de comprendre les mécanismes par lesquels Rho reconnait les transcrits.J’ai identifié un ensemble de déterminants de séquence qui, pris ensemble, possèdent un bon pouvoir prédictif et que j’ai utilisé pour construire le premier modèle computationnel capable de prédire la terminaison Rho-dépendante à l’échelle des génomes d’E. coli et Salmonella. J’ai caractérisé in vitro certains de ces terminateurs, en particulier dans les régions 5’UTR, avec l’espoir qu’ils soient impliqués dans des mécanismes de régulation conditionnelle. J’ai identifié des candidats dont l’activité pourrait être sous le contrôle de facteurs comme des petits ARN non codants (sRNA) ou latempérature. J’ai également développé une méthode fluorogénique pour détecter facilement la terminaison Rho-dépendante in vitro et ai commencé à adapter l’approche CLIP-seq à l’étude du transcriptome Rho-dépendant chez Salmonella. Collectivement, mes travaux offrent de nouveaux outils d’analyse et de prédiction de la terminaison Rho-dépendante, une meilleure cartographie des sites d’action de Rho chez E. coli et Salmonella, ainsi que de nouvelles pistes d’étude du rôle de Rhodans l’expression conditionnelle du génome. / Transcripts at a free Rut (Rho-utilization) site from which Rho moves along the RNA in an ATP dependentfashion to catch up with and dissociate the transcription elongation complex. It is generally believed that the Rut sites are, respectively, rich and poor in Cytosines and Guanines as well as relatively poor in secondary structures. Studies at the genomic or transcriptomic scale have notrevealed any stronger consensus features or rules for predicting potential Rho-dependent termination sites. By combining biochemical and bioinformatics approaches, I have explored the mechanisms by which Rho recognizes transcripts to induce transcription termination. I have identified a complex set of sequence determinants which, taken together, have good predictive power and which I used to build the first computational model able to predict Rho-dependent termination at the scale of Escherichiacoli and Salmonella genomes. I have characterized in vitro some of these terminators, particularly in 5'UTRs, with the hope that they will be involved in conditional regulatory mechanisms. I have identified several candidates whose activity may be under the control of factors such as small non-coding RNAs(sRNA) or temperature. I have also developed a fluorogenic method to easily detect Rho-dependent termination in vitro and have begun to adapt the CLIP-seq approach to the study of the Rhodependent transcriptome in Salmonella. Collectively, my work offers new tools for the analysis and prediction of Rho-dependent termination, a better mapping of the sites of probable Rho action in E.coli and Salmonella, as well as several lines of investigation of the role of Rho in the conditional expression of bacterial genomes.

Translation is the process by which proteins are synthesized from the instructions in the genetic code. Translation is mediated by the ribosome, a large ribonucleoprotein complex, in concert with messenger RNA (mRNA), transfer RNA (tRNA), and a variety of proteins. The canonical mechanism of translation, introduced in Part I of my thesis, is divided into four distinct phases: initiation, elongation, termination, and recycling. Under unusual circumstances, each phase of translation can also proceed via a number of noncanonical mechanisms, many of which are vitally important for cellular growth or viral infectivity. My thesis describes structural insights into two such noncanonical mechanisms. The aim of the first project, described in Part II, was to structurally characterize a noncanonical mechanism of translational termination in bacteria. In the absence of a stop codon, ribosomes arrest at the 3′ end of an mRNA and are unable to terminate. In bacteria, the primary mechanism for rescuing such nonstop complexes is known as trans-translation. In the absence of a functional trans-translation system, however, the small protein ArfA recognizes the empty mRNA channel and recruits the release factor RF2 to the ribosome, enabling termination to occur. Using single-particle electron cryomicroscopy (cryo-EM), I obtained four high-resolution structures of nonstop complexes that reveal the mechanism of ArfA-mediated ribosome rescue and have wider implications for understanding canonical termination in bacteria. The aim of the second project, described in Part III, was to gain structural insights into a noncanonical mechanism of translational initiation in eukaryotes known as internal ribosome entry. Instead of a 5′ cap, many viruses contain intricately structured, cis-acting internal-ribosome-entry sites (IRESs) within their genomes that direct end-independent initiation. The IRES of hepatitis-C virus (HCV), for example, interacts directly with the mammalian ribosome and functionally replaces many of the canonical initiation factors. However, the mechanism by which the HCV IRES coordinates assembly of an initiation complex and progresses through the initiation phase remains poorly understood. I developed a method for purifying native ribosomal complexes from cell lysate that enabled me to obtain multiple cryo-EM maps of the HCV IRES in complex with the 80S ribosome, including a previously unseen conformation of the IRES induced by rotation of the ribosomal small subunit, and to make progress towards capturing earlier steps in the initiation pathway.

La terminaison de la traduction se produit lorsqu’un codon stop entre au site A du ribosome où il est reconnu par le facteur de terminaison eRF1 accompagné du facteur eRF3. Cette étape de la traduction est encore mal comprise chez les eucaryotes. Au cours de ma thèse je me suis intéressée à l’étude de la fidélité de la terminaison de la traduction afin de mieux comprendre et caractériser les mécanismes moléculaires mis en jeu lors du décodage du codon stop.L’un de mes projets consistait à mieux caractériser une région du domaine N-terminal d’eRF1, la cavité P1, identifiée comme étant impliquée dans l’efficacité de terminaison. Grâce à une quantification de l’efficacité de translecture de mutants de la cavité P1, j’ai pu mettre en évidence le rôle de résidus clés comme les serines 33 et 70, impliquées dans le décodage spécifique du codon UGA probablement via une interaction directe entre les deux résidus, ou encore l’arginine 65 et la lysine 109, essentielles pour une terminaison efficace sur les trois codons stop. L’analyse par RMN de ces mutants a également permis de montrer que ces résidus étaient importants pour la conformation correcte de la cavité et potentiellement impliqués dans une interaction directe avec l’ARNm. La combinaison des données génétiques et structurales nous a permis de proposer un modèle d’interaction entre l’ARNm et le facteur de terminaison eRF1 dans lequel le codon stop serait reconnu en partie par l’intermédiaire de la cavité P1. Dans la cellule, la terminaison est toujours en compétition avec la translecture, qui correspond à l’incorporation d’un ARNt proche-cognat au niveau du codon stop. Afin d’identifier les acides aminés incorporés par translecture au niveau du codon stop, j’ai mis au point un système basé sur l’expression et la purification de protéines issues de la translecture qui sont ensuite analysées par spectrométrie de masse. J’ai pu mettre en évidence que la glutamine, la tyrosine et la lysine s’incorporent au niveau des codons UAA et UAG, alors que le tryptophane, la cystéine et l’arginine sont retrouvés au niveau du codon UGA. J’ai également pu montrer que le contexte en 5’ n’influençait pas l’incorporation des acides aminés au codon stop mais qu’en revanche, la présence de la paromomycine avait un impact sur la sélection des ARNt suppresseurs naturels. Ce projet permet d’apporter de nouvelles informations sur les règles de décodage grâce à l’analyse des appariements entre codons stop et anticodons des ARNt naturels suppresseurs. Il permet également d’envisager des perspectives thérapeutiques dans le cadre des maladies liées à la présence d’un codon stop prématuré et pour lesquelles le traitement repose sur l’utilisation de la translecture afin de ré-exprimer des protéines entières. / Translation termination occurs when a stop codon enters the A site of the ribosome where it is recognized by eRF1 (eukaryotic release factor 1), associated with eRF3. This step of translation is not yet understood in eukaryotes. During my PhD, I was interested in studying translation termination accuracy to better understand and characterize the molecular mechanisms involved in stop codon decoding.One of my project consisted in characterizing a region in eRF1 N-terminal domain, pocket P1, identified to be involved in termination efficiency. Through a quantification of readthrough efficiency of pocket P1 mutants, I have highlighted the role of key residues, like serine 33 and serine 70, implicated in specific recognition of UGA stop codon, probably through a direct interaction between the two amino acids, and also arginine 65 and lysine 109, essential for efficient termination on the three stop codons. The analysis of the mutants by NMR revealed that these residues are also important for proper conformation of the cavity and potentially involved in a direct interaction with mRNA. The combination of our genetic data and structural analysis allowed us to propose a model of interaction between termination factor eRF1 and the mRNA, in which the stop codon would be recognized partially through pocket P1.In cells, termination always competes with readthrough which corresponds to the incorporation of near-cognate tRNAs at the stop codon. To identify the amino acids inserted by readthrough at the stop codon, I have developed a reporter system based on the expression and purification of readthrough proteins that are analyzed by mass spectrometry. I found that glutamine, tyrosine and lysine are inserted at UAA and UAG stop codons, whereas tryptophan, cysteine and arginine are inserted at UGA stop codon. I also showed that the 5’ nucleotide context does not influence the incorporation of amino acids at the stop codons by readthrough, but that, in contrast, the presence of paromomycin impacted the selection of natural suppressors tRNAs incorporated by readthrough. This project gives us new insights into the decoding rules by analyzing the base pairings between stop codon and near-cognates anticodons. It also allows us to consider therapeutic prospects for the treatment of premature stop codon diseases which uses readthrough as a tool to re-express full-length proteins from mRNAs that are interrupted by the presence of a premature stop codon.

La terminaison de la transcription est essentielle, aussi bien pour assurer la formation de l’extrémité 3’ de transcrits fonctionnels que pour éviter les phénomènes d’interférence transcriptionnelle entre des régions transcrites adjacentes. Ceci est particulièrement important dans un génome compact comme celui de S. cerevisiae. La terminaison est aussi l’une des stratégies principales que la cellule emploie pour contrôler et limiter la transcription dite envahissante ou cachée. Chez S. cerevisiae, l’ARN polymérase II est responsable de la transcription des ARNm et de nombreuses classes d’ARN non codants tels que les sn(o)ARN et les CUT (Cryptic Unstable Transcripts). Ces derniers représentent une fraction importante des transcrits issus de la transcription cachée. Il existe deux voies canoniques de terminaison de la transcription par cette polymérase. Elles font intervenir le complexe de clivage et de polyadénylation, CPF-CF, notamment pour la terminaison des ARNm ou le complexe NNS pour la terminaison des sn(o)ARN et des CUT. Au cours de ma thèse j’ai étudié deux aspects de la terminaison de la transcription : 1) l’étude des motifs de recrutement du complexe NNS et 2) l’identification et la caractérisation d’une nouvelle voie de terminaison par le facteur Rap1. Les complexes CPF-CF et NNS agissent tous les deux en liant le transcrit naissant et l’ARN pol II. Le complexe NNS lie l’ARN naissant grâce à ses sous-unités Nrd1 et Nab3 qui reconnaissent des motifs spécifiques. Cependant, bien que la séquence de ces motifs soit maintenant connue, leur présence ne permet pas de définir de façon certaine un terminateur. En effet, le nombre de ces motifs varie beaucoup d’un terminateur à l’autre. Afin de mieux comprendre la structure des terminateurs ciblés par le complexe NNS et l’organisation des motifs liés par Nrd1 et Nab3, j’ai recherché les séquences impliquées dans la terminaison d’un CUT modèle en réalisant une mutagenèse aléatoire et j’ai identifié par SELEX des motifs de fixation optimale du dimère Nrd1-Nab3. Un second volet de ma thèse porte sur la caractérisation d’une nouvelle voie de terminaison de la transcription dépendante du facteur Rap1. Rap1 est important pour la structure des télomères et c’est aussi un facteur de transcription ciblant des centaines de promoteurs. Il active ou réprime l’initiation de la transcription notamment en recrutant des complexes de remodelage de la chromatine sur les promoteurs ciblés. De façon surprenante, le motif de fixation de ce facteur a été identifié dans des séquences capables de terminer la transcription isolées au laboratoire. Mes travaux ont permis de caractériser le mécanisme de terminaison par Rap1 et de distinguer cette voie des voies de terminaison canoniques. Ce facteur, lié à l’ADN, agit comme une barrière en bloquant la progression de l’ARN polymérase II par un mécanisme de « road-block ». Les polymérases ainsi arrêtées sont ciblées par une voie qui permet leur élimination lorsqu’elles sont bloquées par des dégâts sur l’ADN, impliquant leur ubiquitination et vraisemblablement leur dégradation par le protéasome. Les ARN libérés sont polyadénylés par la poly(A)-polymérase Trf4 et dégradés par l’exosome nucléaire. Ce mécanisme de terminaison est utilisé dans un contexte naturel puisque j’ai identifié des transcrits endogènes de S. cerevisiae terminés par cette voie. Nous proposons que la terminaison par Rap1 contribue au contrôle de la transcription envahissante. Ce facteur assurerait ainsi au niveau des promoteurs qu’il lie une double fonction de facteur de transcription et de protection de ces promoteurs contre l’interférence transcriptionnelle. / Transcription termination is essential, both for the 3’ end formation of functional transcripts and to avoid transcriptional interference between adjacent transcription units. This is particularly important in a compact genome such as S. cerevisiae. Termination is also one of the main strategies used by the cell to control and limit the “pervasive” or “hidden” transcription. In S. cerevisiae, RNA pol II is responsible for the transcription of the mRNAs and numerous non-coding RNA families such as the sn(o)RNAs and the CUTs (Cryptic Unstable Transcripts). CUTs represent a large fraction of the “pervasive” or “hidden” transcription. There are two canonical transcription termination pathways for this RNA polymerase. They involve the cleavage and polyadenylation complex (CPF-CF), in particular for the mRNAs termination, or the NNS complex for sn(o)RNAs and CUTs termination. During my thesis I studied two aspects or the transcription termination: 1) the motifs involved in the NNS complex recruitment on RNA and 2) the identification and the characterization of a new termination pathway by Rap1. CPF-CF and NNS complex are both recruited on the nascent transcript and on the RNA pol II. The NNS complex binds the RNA through its subunits Nrd1 and Nab3 which recognize specific motifs. Nonetheless, even if these motif sequences are now known, their presence does not elicit the certain identification of NNS dependent terminators. To clarify the NNS dependent terminator structure and the organization of the motifs bound by Nrd1 and Nab3 I looked for the sequences involved in a specific CUT termination doing a random mutagenesis experiment and I identified by SELEX the Nrd1-Nab3 dimer optimal binding motifs. A second part of my thesis concerns the characterization of a new transcription termination pathway dependent on the Rap1 factor. Rap1 is important for the telomere structure and it is also a transcription factor that targets hundred of promoters. It activates or represses transcription initiation recruiting chromatin remodeling complexes on the targeted promoters. Surprisingly, the Rap1 binding motifs have been identified among sequences eliciting termination isolated in the laboratory. My work has led to the characterization of the termination mechanism by Rap1 and distinguished this pathway from the two canonical pathways. This factor, bound to DNA, acts as a barrier blocking the RNA pol II progression by a road-block mechanism. These arrested polymerases are targeted by a pathway responsible for the elimination of RNA pol II blocked by DNA damages, implying their ubiquitination and probably their degradation by the proteasome. The released RNAs are polyadenylated by the poly(A) polymerase Trf4 and degraded by the nuclear exosome. This termination mechanism is used in a natural context since I identified S. cerevisiae endogenous transcripts terminated by this pathway. We propose that the Rap1 termination contributes to the pervasive transcription control. This factor could elicit, on its bound promoters, a double function of both transcription factor and protection of these promoters against transcriptional interference.

Eles protagonizaram o apogeu do basquetebol brasileiro nos anos 50 e 60. Representaram o país vitoriosamente em diversas competições, sendo as conquistas dos títulos mundiais em 1959 e 1963, e as medalhas de bronze olímpicas em 1960 e 1964, os feitos mais emblemáticos. Mas embora desfrutassem de certa notoriedade por estes feitos, não foram isentos das implicações do amadorismo esportivo. A profissionalização da carreira atlética ainda era uma realidade distante para eles, e a dedicação ao esporte, para que pudesse ser legítima, tinha que ser majoritariamente voluntária e gratuita. Essas e outras configurações influenciaram decisivamente a forma como os bicampeões mundiais de basquetebol geriram suas carreiras e passaram pela transição respectivamente. O objetivo desta pesquisa foi trazer elementos para a reflexão e compreensão do fenômeno transição de carreira no esporte, analisando os significados e características deste processo por meio das narrativas biográficas dos bicampeões mundiais Wlamir Marques, Amaury Pasos, Rosa Branca, Antônio Sucar, Carlos Massoni, Luiz Claudio Menon, Jatyr Schall, Waldyr Boccardo, Friedrich Fritz e Vitor Mirshawka. Analisadas a luz do modelo de adaptação humana à transição de Schlossberg e das considerações teóricas sobre a transição de carreira no esporte, as narrativas sugeriram que a saída do papel de atleta, bem como o processo de mudança para outras esferas da vida, foram experiências decisivamente marcadas pelo momento histórico ao qual os bicampeões pertenciam. Nos tempos de amadorismo o apoio financeiro à carreira atlética era escasso, condição que requereu dos atletas a adoção de uma estratégia de gestão de carreira atlética que conjugasse prática esportiva com formação acadêmica e emprego remunerado. Esse trânsito contínuo entre carreira atlética e outros interesses estreitou a relação dos bicampeões com a vida cotidiana de maneira que seus términos e transições de carreira puderam ocorrer sem maiores dificuldades. As situações estruturantes dessa qualidade de transição caracterizam-se pela concorrência de atividades determinando a tomada de decisão pela priorização de interesses; pela possibilidade de mover-se para dentro ou dar continuidade à vida profissional dentro do contexto esportivo como professor, técnico ou gestor; pela possibilidade de realização em outras esferas da vida, e, por fim, pela presença de sistemas de suporte informais (família e amigos). As narrativas biográficas alertaram ainda para a dificuldade enfrentada pelos bicampeões no que se refere à conciliação da carreira atlética com a vida para além do esporte, bem como para a ausência de sistemas de suporte formais (apoio institucional, especializado, previdência social para atletas) para a transição e vida pós-atleta / They played leading roles in the heyday of Brazilian basketball in the 50s and 60s. They represented the country triumphantly in a range of competitions, the most emblematic of their achievements being victories at the world championships in 1959 and 1963, and the Olympic bronze medals in 1960 and 1964. But although they enjoyed a certain level of notoriety as a result of these achievements, they weren\'t exempt from the implications of being amateur sportsmen. The athletic career as a profession was still a distant reality for them, and in order to be legitimate, their dedication to the sport had to be overwhelmingly voluntary and unpaid. These and other aspects decisively influenced both the way in which the two-time basketball champions managed their careers, and how they went through transitions, respectively. The objective of this research was to provide elements for the reflection and understanding of the phenomenon of career transition in sport, analyzing the significance and characteristics of this process through the narrative biographies of the two-time world champions Wlamir Marques, Amaury Pasos, Rosa Branca, Antônio Sucar, Carlos Massoni, Luiz Claudio Menon, Jatyr Schall, Waldyr Boccardo, Friedrich Fritz and Vitor Mirshawka. Analyzed in the light of Schlossberg\'s model of human adaptation and transition, and the theoretical reflections on career transition in sport, the narratives suggested that withdrawal from the role of an athlete, as well as the process of shifting to other spheres of life, were experiences decisively marked by the historical moment to which the two-time champions belonged. In this period where sport was an amateur affair, financial support for their athletic careers was scarce, a condition which required the athletes to adopt a strategy for managing their career which would unite sport training with education and gainful employment. This continuous compromise between athletic career and other interests gave the two-time champions such a close relationship with everyday life that the terminations and transitions of their careers were able to occur without great difficulties. The situations that give rise to this aspect of the transition are characterized by a multitude of activities making it necessary to prioritize interests; by the possibility of staying within or continuing with professional life within a sporting context as an instructor, coach or manager; by the possibility of success in other spheres of life, and, lastly, by the presence of informal support systems (family and friends). The narrative biographies brought further to light the difficulty faced by the two-time champions with regard to the reconciliation of their athletic careers with the world outside of sport, as well as the absence of formal support systems (institutional, specialized support, welfare for athletes) for the transition and life after sport

Au cours de mon travail de thèse j’ai étudié la relation entre les facteurs participant à la terminaison de la traduction et ceux participant à la dégradation des ARNm chez S. cerevisiae.D’une part, je me suis intéressée au facteur Tpa1, caractérisé pour son rôle dans la terminaison de la traduction et la stabilité des ARNm chez S. cerevisiae et dont l’homologue chez S. pombe, Ofd1, participe au contrôle de la réponse hypoxique. Je me suis basée sur la structure de ce facteur, établie par nos collaborateurs pour comprendre plus précisément la fonction moléculaire de Tpa1 et rechercher des similitudes avec sa fonction chez S. pombe.Tpa1 est composée de deux domaines de type DSBH dont le premier, contenant le site catalytique, présente des homologies structurales avec la famille des prolyl-hydroxylases.Nous avons reproduit l’effet de la protéine Tpa1 sur la translecture in vivo et montré que son site catalytique prédit, ainsi que la présence des deux domaines étaient nécessaires pour cette activité. Nous avons aussi observé que Tpa1 inhibait par un mécanisme inconnu le facteur de transcription Hap1, qui régule des gènes en fonction de la quantité d’oxygène. Basé sur l’existence d’un inhibiteur d’Ofd1 chez S. pombe, nous avons ensuite montré qu’Ett1 (l’homologue de cet inhibiteur chez S. cerevisiae) avait un rôle similaire à Tpa1 dans la translecture. Une étude structurale collaborative d’Ett1 a mis en évidence une région conservée, se liant à une molécule de sulfate et à un ligand inconnu. Cette région est importante pour la translecture. Cependant, le substrat de Tpa1 reste pour l’instant inconnu comme les rôles précis de Tpa1 et Ett1 dans la terminaison de la traduction et dans la réponse à l’hypoxie.D’autre part, j’ai étudié le processus de NMD, particulièrement en me focalisant sur le mécanisme de discrimination entre un codon stop précoce (PTC) et un codon stop normal, et en analysant également la modification post-traductionnelle d’un facteur central du NMD, Upf1. Nous avons mis en évidence, qu’en plus de la région aval, la région en amont du PTCparticipait à sa reconnaissance. Nous avons testé plusieurs hypothèses sur le rôle de cette région, qui ont confirmé son rôle sans permettre de démontrer un mécanisme définitif. En parallèle, l’étude de la protéine Upf1 s’est concentrée sur ses modifications posttraductionnelles, particulièrement par phosphorylation. En effet, une telle modification est importante chez son homologue humain. Nous avons pu confirmer l’existence d’une forme modifiée et démontrer que celle-ci était localisée entre les acides aminés 153 et 971. Cette modification s’est avérée être très labile ce qui n’a pas permis de confirmer qu’il s’agissait d’une phosphorylation, ni de la cartographier plus précisément. / During my PhD thesis, I analyzed the relation between factors that participate intranslation termination and those participating in mRNA decay in yeast S. cerevisiae.First, I focused on Tpa1, that had been proposed to participate in translationtermination and mRNA decay in S. cerevisiae, and whose homologue in S. pombe, Ofd1,participates to the control of hypoxic response. Based on the structure of Tpa1, established byour collaborators, I performed functional analysis to understand more precisely the molecularfunction of Tpa1 and similarities with its role in S. pombe. Tpa1 is composed of two DSBHdomains; the first, which contains the catalytic site, has structural homologies with the familyof prolyl-hydroxylase. We could reproduce the effect of Tpa1 on stop codon readthrough invivo and we showed that the predicted catalytic site and the presence of the two domains ofTpa1 were necessary for its activity. We also showed that Tpa1 inhibited one factor, Hap1,implicated in regulation of gene expression by oxygen. The existence of an inhibitor of Ofd1in S. pombe, allowed the identification of Ett1 (its homologue in S. cerevisiae). We showedthat Ett1 has a role similar to the one of Tpa1 in translational readthrough. A collaborativestructural and functional study of Ett1 revealed a conserved region, which binds a sulfate ion,and an unknown ligand. This region is important for the readthrough. However, thesubstrate(s) of Tpa1 remain(s) for the moment unknown, and the precise roles of Tpa1 andEtt1 in translation termination and in response to hypoxia remain to be deciphered.I also analyzed the NMD process by focusing more particularly on the mechanism thatallows the discrimination between a normal stop and a PTC (premature termination codon)and on the analysis of the post-translational modification of an important factor for the NMD,Upf1. This study revealed that, not only the region downstream of the PTC but also theupstream region participates to its recognition. We have tested several hypotheses on the roleof this upstream region, which confirmed its implication but did not reveal a definitivemechanism. In parallel, we started the study of the post-translational modifications of Upf1,and more particularly by phosphorylation. Indeed, the phosphorylation of Upf1 in human isvery important for the NMD process. We could confirm the presence of a modified form ofyeast Upf1 and we have demonstrated that it was localized between amino acids 153 and 971.This modification appeared to be highly labile. This prevented us to confirm definitively thatit was really a phosphorylation and to cartography precisely its location.

Thesis (MPH.) -- University of Limpopo, 2014 / Legalising Termination of Pregnancy (TOP) in South Africa has given women the choice to decide to terminate an unwanted pregnancy. The implementation of the Choice on Termination of Pregnancy (CTOP) Act No. 92 of 1996 which was promulgated in 1997 engendered many challenges for the registered midwives performing TOP. A qualitative phenomenological study was conducted to explore and describe the experiences of registered midwives performing TOP at Polokwane / Mankweng Hospital Complex, which is one of the public hospitals in Limpopo Province. Registered midwives with 12 months or more experience in the TOP clinics participated in this study. Interviews were conducted with the participants. The audiotaped interviews and observational notes were transcribed and coded using Tesch’s qualitative and systematic approach of analysing textual data. The major themes that emerged from the data analysis include lack of resources, emotional and psychological trauma, lack of support, religious and cultural beliefs, blaming and coping mechanisms. Several sub-themes were identified that reflected the themes in greater detail. These were shortage of human and material resources, stress and frustration of midwives, rejection and labelling of midwives performing TOP, conscientious objection, cultural beliefs, lack of support by colleagues and management, failure by the community to use contraceptives, self-blaming, debriefing to assist registered midwives and self-acceptance. Guidelines based on contextualisation of these themes and sub-themes to improve identified challenges included retention of personnel through recognition and incentives, increase budgeting for essential equipment, planned debriefing sessions, promotion of positive attitudes by colleagues and intense training on reproductive health, including TOP.

O tema desenvolvido na presente pesquisa refere-se ao contrato de agência, no qual se identifica a inerência da situação de dependência econômica do agente, parte normalmente mais frágil em relação ao proponente. Esta situação de dependência econômica, apesar de não ser vedada a priori pelo ordenamento jurídico, pode dar ensejo ao seu abuso por parte do proponente, mediante a imposição de condições ao agente, às quais este deve anuir por não possuir alternativa viável. Dentre as possibilidades de abuso de dependência econômica pelo proponente, concentrou-se naquela manifestada na resilição unilateral abusiva do contrato, especialmente quando existem investimentos específicos, exigidos do agente, que ainda não foram amortizados ou recuperados pela duração do contrato. Tomando-se como premissa o fato de que tanto a Lei nº 4.886/1965 quanto o Código Civil de 2002 disciplinam especificamente a relação de agência, pode-se verificar que ambos os diplomas normativos possuem dispositivos legais que visam à proteção do agente, mitigando os efeitos da posição de supremacia do proponente no contrato e diminuindo a possibilidade de exercício abusivo da dependência econômica do agente. Esses mecanismos protetivos, no entanto, por estarem previstos em dois diplomas legais diversos, que não possuem qualquer referência expressa um ao outro, não se encontram adequadamente sistematizados, causando dúvidas sobre a sua correta interpretação e aplicação. Dessa forma, após a identificação e estudo de cada uma das ferramentas protetivas consagradas pela legislação específica, foi proposta uma sistematização que se entende a mais adequada para conferir proteção ao agente, conforme pretendido tanto pela Lei nº 4.886/1965 quanto pelo Código Civil, assim como segurança e certeza às partes, servindo como estímulo para as contratações de longo prazo e para a realização de investimentos, de modo a contribuir para a eficiente utilização do contrato de agência, que é importante ferramenta para a promoção do desenvolvimento econômico e social. / The theme developed in the present research refers to the agency agreement, in which exists a inherent economic dependence of the agent, usually the more fragile part in relation to the principal. This situation of economic dependence, although not prohibited by the legal system, can give rise to its abuse by the principal, by imposing conditions on the agent, which the agent must accept because he has no viable alternative. Among the possibilities of abuse of economic dependence by the principal, this research focused on the unilateral termination of the contract especially when there are specific investments made by the agent that have not yet been amortized or recovered during the contract. Taking as a premise that both the Lei nº 4.886/1965 and the Civil Code of 2002 specifically regulate the agency agreement, it can be verified that both normative documents have legal provisions that aim at the protection of the agent, mitigating the effects of the principal supremacy position in the contract and reducing the possibility of abusive exercise of the agent\'s economic dependence. These protective mechanisms, however, because they are in two different legal texts, which do not have any express reference to each other, are not adequately systematized, causing doubts about their correct interpretation and application. Thus, after the identification and study of each of the protection tools provided by the specific legislation, a systematization was proposed that is considered the most appropriate to grant protection to the agent, as intended by the Lei nº 4.886/1965 and by the Civil Code, and to provide security and certainty to the parties, serving as a stimulus for long-term contracting and for the realization of investments, in order to contribute to the efficient use of the agency contract, which is an important tool for the promotion of economic and social development.

Le contentieux contractuel éclate lorsque l'une des parties n'exécute plus ou pas ses obligations. La préoccupation essentielle en matière contractuelle, consiste à lutter contre une rupture abusive et arbitraire du contrat. La particularité du droit civil français en matière de rupture du contrat, est la place très importante qu'occupe le juge judiciaire. L'assurance de la protection des intérêts des parties et la garantie d'une sanction juste et équitable, reposent en effet, sur les épaules du juge. Il est par conséquent inconcevable que le juge soit écarté du jeu de la rupture contractuelle. L'orientation traditionnelle a toujours fait du juge un pilier dans le domaine de la séparation contractuelle, mais cette tendance commence quelque peu à se dissiper. Le juge doit toujours jouer un rôle très important en droit des contrats en général et dans sa rupture en particulier. Une protection efficace des parties donnerait à l'intervention du juge une utilité plus importante. Il est primordial, que le juge soit un acteur, en matière de rupture contractuelle, dont le rôle serait la garantie du respect des lois et la protection complète des parties ; le cas contraire, pourrait réduire alors la portée du code civil actuel à un simple catalogue de lois régissant l'anéantissement du contrat. / Contractual litigation arises when one of the parties fails to fulfill its obligations. Its main concern is to fight against abusive and arbitrary breach of contracts. In the French civil law, the judge occupies a very important place when debating breach of contracts. It is impossible to alienate the judge when it comes down to contract breaches. In fact, he insures that the interests of every concerned party are protected. He also guarantees that fair and equitable sanctions will be applied. Traditionally, the judge was very important when discussing breach of contracts. However, this trend is beginning to dissipate. In general, the judge plays a very important role in contract law, but his role is primordial when disputing contract termination. Effective protection of the parties would give the intervention of the judge a greater utility. It is essential that the judge remains an important actor when it comes to breach of contract as his role is to guarantee that the law is respected and that every party is adequately protected. On the contrary, it could reduce the importance of the current Civil Code to a mere catalog of laws governing the annulment contracts