Nas últimas décadas, a praia de Massaguaçu vem sofrendo processos erosivos intensos, cujos segmentos possuem taxas de recuo acentuadas, denominadas Zonas de Erosão Acentuada (ZEAs). Partindo deste problema este trabalho se propôs a entender a dinâmica sedimentar do arco praial de Massaguaçu e das possíveis causas de formação e manutenção das ZEAs. A coleta de dados se baseou no levantamento batimétrico e do clima de ondas, bem como no levantamento sonográfico de varredura lateral e na coleta de amostras de sedimento de superfície da antepraia de Massaguaçu. Para processar os dados se optou pela aplicação da modelagem numérica utilizando o modelo SWAN (propagação de ondas em águas profundas) e o modelo SMC (módulos OLUCA, COPLA e EROS, que trabalham, respectivamente, com propagação de ondas em águas rasas, simulação de correntes e simulação de transporte sedimentar). Para a formulação da discussão foram selecionados os 6 (seis) casos que apresentaram as condições de ondas mais representativas. Tais casos mostraram que a dinâmica sedimentar e os processos costeiros responsáveis pela formação e manutenção das ZEAs são controlados por dois padrões distintos de ondas incidentes. O primeiro padrão está relacionado às ondas vindas de NE - E, que geram correntes longitudinais para o sul. Suas correntes longitudinais e transversais à costa são de baixa intensidade resultando em um transporte sedimentar e em variações da morfologia praial menos intensos, além de formar células de circulação em vórtices. O segundo padrão, por sua vez, está relacionado às ondas oriundas SSE - SE - ESSE, cujas correntes litorâneas longitudinais rumam ao norte. Tais correntes longitudinais e transversais à costa, apresentam uma intensidade maior, portanto o transporte sedimentar e as variações da morfologia ao longo do arco praial são maiores bem como as células de circulação em vórtices. Partindo desses resultados, percebeu-se que as ZEAs em Massaguaçu estão ligadas a um possível aumento na frequência e na intensidade das tempestades ao longo das últimas décadas e até o presente momento, não há mecanismos naturais que revertam esta retração da linha de costa. / Over the past decades in Massaguaçu beach has happening a strong erosion process with segments that have higher retreat rates, commonly termed as Erosional Hot Spots (EHSs). This research aims the understanding of the sedimentary dynamics along the Massaguaçu embayment and also the possible causes of the formation and maintenance of the EHSs. The methodology was separately on two steps. At first we collected bathymetry, wave and side-scan sonar data, and samples of the surface sediments from the shoreface of Massaguaçu beach. Later, to analyze majority data, we chose to use numerical modeling based on the SWAN model (propagation of waves in deep water) and SMC model (modules OLUCA, COPLA and EROS, that work respectively with the propagation of waves in shallow water, the simulation of currents and finally the simulation of sediment transport). After modeling, we were able to select the 6 (six) most representative wave conditions cases. Those results show that the control of the sediment dynamics and the coastal processes responsible for the formation and the maintenance of ZEA are based on the characteristics of the incident waves. On trying to explain that process, it was possible to recognize two distinct patterns. The first pattern observed is associated with the NE - E waves, generating longshore currents to the south. In this case, both the longshore and the crosshore currents are less intense, forming cells circulation in vortex, resulting in minor variations in sediment transport and beach morphology. The second pattern is related with the SSE - SE - ESE waves, generating longshore currents to the north. In this case both the longshore and the crosshore currents are more intense, although still with occurrence of forming cells circulation in vortex, resulting in a larger sediment transport and morphological changes along the beach. Finally, what we have seem was that the ZEAs in Massaguaçu are possibly linked to a potential increment on storms frequency and intensity over the past decades and unfortunately, at present, there is still no mechanism to recover this natural retreat of the coastline.

Le dimensionnement au crash des structures automobiles en matériaux composites à renforts discontinus tels que les SMC est généralement réalisé sur la base de données expérimentales recueillies sur des matériaux vierges n’ayant subi aucun chargement depuis leur mise en œuvre. Or, les accidents proviennent après quelques années de mise en service durant lesquelles la structure composite est soumise généralement à des sollicitations de type fatigue à plus ou moins grande amplitude. La prise en compte d’un pré-endommagement éventuel en fatigue devient alors essentielle si l’on veut rester réaliste. Par ailleurs, de nouvelles formulations de matériaux composites SMC ont été récemment développées. Leur comportement en fatigue et sous sollicitation rapide étaient jusqu’à lors inexplorés. Cette étude à caractère fortement expérimentale a donc pour but d’apporter la connaissance nécessaire au dimensionnement de structures en matériaux SMC de diverses formulations, notamment le A-SMC et le LD-SMC. Le premier correspond à une matrice vinylester fortement renforcée de mèches de fibres de verre (50%). Le second correspond à une formulation proche de celle d’un SMC standard dans laquelle on a rajouté un fort taux de billes de verre creuse afin de réduire la densité. Une analyse multi-échelle permet de mettre en évidence l’influence de la microstructure sur les phénomènes d’endommagement sous sollicitation quasi-statique, dynamique et fatigue. Des méthodes originales d’analyse expérimentale sont développées afin de corréler ces mécanismes aux comportements macroscopiques observés. Les essais dynamiques rapides optimisés sont réalisés jusqu’à des vitesses de déformation de l’ordre de 80 s-1 et mettent en évidence un comportement visco-endommageable pour les deux matériaux SMC étudiés. Le décalage du seuil d’endommagement et la baisse de la cinétique d’endommagement observés à l’échelle macroscopique sont directement corrélés au seuil et cinétique des mécanismes d’endommagement observés à l’échelle locale telles que la rupture à l’interface fibre-matrice ou bille-matrice, la microfissuration de la matrice et le pseudo-délaminage entre les mèches de fibres de verre. Par ailleurs, une analyse multi-échelle du même type est également réalisée sous sollicitation de type fatigue dans laquelle les fréquences varient de 10 à 100 Hz. Une étude de l’influence des phénomènes d’auto-échauffement sur l’endommagement et le comportement du A-SMC est proposée. Enfin, une analyse originale des propriétés résiduelles sous sollicitation rapide d’échantillons préalablement fatigués à différents niveaux de fraction de durée de vie met en évidence une forte influence de l’histoire du chargement sur la sensibilité du A-SMC à la vitesse de sollicitation. L’ensemble des résultats de cette étude, de par son apport de compréhension des phénomènes mis en jeu, constitue la base expérimentale nécessaire à la construction d’outils de dimensionnement adaptés aux structures SMC sous sollicitations cycliques et dynamiques. / Classically, crash design of automotive composite structures made of discontinuous reinforcements such as SMC is usually based on experimental data obtained from virgin materials without any history of loading. However, crash events always occur after a few years of use during which composite structure is generally subjected to more or less important fatigue loading. Taking into account of a potential pre-damage in fatigue becomes essential if we want to stay realistic. Moreover, new formulations of SMC composites have been developed recently. Up to now, their fatigue and dynamic behavior were never being explored. This study, of a mostly experimental nature, aims to provide the knowledge necessary for design of structures made of various SMC formulations including A-SMC and LD-SMC. The first one is a vinylester matrix reinforced with a high content of glass fibers (50%). The second corresponds to a standard SMC formulation in which we added a high content of hollow glass micro-sphere in order to reduce density. A systematic multi-scale analysis allows to highlight the influence of the microstructure on damage phenomena under quasi-static, dynamic and fatigue loading. Original experimental methods are developed to correlate these mechanisms to the observed macroscopic behavior. Optimized dynamic tests are performed at strain rate up to 80 s-1 and highlight a visco-damageable behavior for the two SMC materials in study. Damage threshold delay and reduction of damage kinetics observed at the macroscopic scale are directly correlated to the threshold and kinetic of damage development observed at the local scale such as fiber-matrix or matrix-microsphere interfaces, matrix micro-cracking and pseudo-delamination between the bundles of glass fiber. Moreover, a similar multi-scale analysis is also performed under fatigue loading in which the frequency ranges from 10 to 100 Hz. A study of the influence of the self-heating phenomenon on the fatigue damage behavior of A-SMC is proposed. Finally, an original analysis of the remaining dynamic properties of samples which were previously submitted to fatigue loading until different levels of lifetime highlights a strong influence of the history of the loading on the strain rate sensitivity of the A-SMC. Considering the high contribution of this study in term of comprehension of the phenomena involved in the mechanical response of SMC materials, all of the experimental findings of this study provide the physical background crucial to build structural design tools for SMC subjected to cyclic and dynamic loading.

Les trois complexes SMC Cohésine, Condensine et SMC5/6 sont principalement étudiés pour leurs rôles mitotiques, cependant tous trois sont localisés à proximité des fourches de réplication en condition de stress réplicatif. Au cours de cette thèse, nous nous sommes particulièrement intéressés aux complexes Cohésine et Condensine. Dans une première partie, nous décrivons un nouveau rôle des condensines dans la progression des fourches de réplication en condition de stress réplicatif à l’hydroxyurée (HU) et au Méthyl-Méthane-Sulfonate (MMS). Nos données montrent que dans ces conditions, les condensines limitent l’accumulation de la protéine de liaison à l’ADN simple-brin RPA (Replication Protein A) à proximité des fourches de réplication. Ces résultats révèlent que les condensines limitent l’exposition d’ADN simple brin et pourraient ainsi protéger l’intégrité des fourches de réplication et la stabilité du génome. Dans une seconde partie nous décrivons le mécanisme de recrutement du complexe Cohésine aux fourches de réplication en condition de stress réplicatif. Dans ces conditions, les cohésines renforcent la cohésion des chromatides sœurs afin de faciliter le redémarrage des fourches de réplication par recombinaison homologue. Nous montrons que le complexe SMC-like MRX (Mre11-Rad50-Xrs2), l’histone méthyle-transférase Set1 et l’histone acétyle-transférase Gcn5 sont requis pour le recrutement des cohésines aux fourches de réplication. Nos données révèlent qu’en réponse au stress réplicatif, Gcn5, Set1 et MRX modifient la dynamique des histones. Gcn5 et MRX réduisent la densité d’histone sur l’ADN répliqué alors que Set1 maintient la mobilité des nucléosomes. La modification de la dynamique des histones semble importante pour une réponse cellulaire efficace au stress réplicatif et pour le chargement de complexes SMC aux fourches de réplication. / The three SMC complexes Cohesin, Condensin and SMC5/6 are mainly studied for their role in mitosis, nevertheless they all localize at replication forks in replicative stress conditions. During this thesis, we focused on Cohesin and Condensin. In the first part we describe a new role for the condensin complex in response to replicative stress. In the presence of Hydroxyurea (HU) and Methyl-Methan-Sulfonate (MMS), condensin is required for cell growth and replication fork progression. Moreover, our results show that condensin limits the accumulation of the specific single-strand DNA (ssDNA) binding protein RPA (Replication Protein A) in the vicinity of replication forks under HU treatment, revealing that condensin limits ssDNA accumulation during replicative stress. In this way, Condensin could protect replication fork integrity and genome stability in response to replicative stress. In the second part, we decipher the cohesin recruitment mechanisms at replication fork under replicative stress. In that context, cohesin reinforces sister chromatid cohesion and facilitates homologous recombination (HR) dependent replication fork restart pathways. We show here that the SMC-like MRX complex, the histone methyl transferase Set1 and the histone acetyl transferase Gcn5 are required for cohesin recruitment at stalled replication forks. Our results show that these three proteins affect histone H3 dynamics on replicated DNA in response to replicative stress. Gcn5 and MRX reduce H3 density whereas Set1 maintains nucleosome mobility. These two parameters seem to be important for efficient response to replicative stress and for SMC complexes loading close to stressed replication forks.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-04-13T12:35:48Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação_Mestrado_Gabriel_Dannunzio_Gomes_Junior.pdf: 5445671 bytes, checksum: 0fbfa28afa66b0dd5cc8217c1d6c2418 (MD5) / Made available in DSpace on 2016-04-13T12:35:48Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação_Mestrado_Gabriel_Dannunzio_Gomes_Junior.pdf: 5445671 bytes, checksum: 0fbfa28afa66b0dd5cc8217c1d6c2418 (MD5) Previous issue date: 2015-08-26 / Existe uma crescente atenção voltada para o tema erosão costeira, devido principalmente à mudança climática de causas antrópicas, que está induzindo ao lento e gradual aumento do nível dos oceanos de forma irreversível a curto prazo, de acordo com a grande maioria dos cientistas do clima. Outro fator que influencia no aumento do risco de erosão costeira é a ocupação antrópica desordenada da área de pós-praia, que serve como proteção natural, bem como reserva de sedimentos para a área de praia, e que está constantemente sendo modificada pela ação das ondas e da corrente costeira. Este trabalho possui dois focos principais que estão interconectados. O primeiro trata do estudo de um caso de intervenção antrópica numa área de praia altamente suscetível à erosão costeira, numa zona urbana densamente povoada no litoral da zona metropolitana do Recife. Esta intervenção consiste na construção de um quebra-mar, com a intenção de proteger esta área de praia resultou na transferência da problemática da erosão costeira para a praia ao Norte. Numa segunda tentativa de resolver o problema, foi adotada uma terceira configuração que aparentemente teve um impacto positivo na prevenção da erosão costeira. Estudou-se os três cenários de configuração deste quebra-mar, utilizando-se de um pacote de software de simulação de ondas, correntes costeiras e transporte de sedimento, com o objetivo específico de se estudar, testar e encontrar soluções que possam eliminar a erosão costeira. O segundo foco deste trabalho trata-se de estudar o clima de ondas da região, através de medições feitas por um ondógrafo direcional durante um período de três anos. Para esta finalidade, desenvolveu-se uma metodologia de classificação das ondas a partir do espectro direcional, obtido através das medições, de forma a se distinguir com mais clareza as características de cada sistema de ondas que fazia parte deste espectro. Após esta etapa foi feita uma comparação entre o clima de ondas obtido através das medições, com o clima de ondas que faz parte da base de dados que acompanha o pacote de software utilizado na primeira etapa deste trabalho, de forma a validar o uso do software como uma ferramenta confiável no estudo do impacto da erosão. O resultado da comparação foi que o software possui uma base de dados confiável, mas que precisa de alguns ajustes para obter uma melhor descrição do clima de ondas da região. / There is increasing attention on the coastal erosion issue, mainly due to anthropogenic causes, first on the climate change, which led to the slow and gradual sea level rise, and also by the irregular occupation of the post-beach area, which serves as a natural protection and a sediment reserve to the beach area, which is constantly being modified by wave action and coastal currents. This work has two main focuses which are interconnected. The first is the study of a human intervention case in a beach area highly susceptible to coastal erosion in a densely populated urban area on the coast of the metropolitan area of Recife. This intervention , made by installing a breakwater with the intention to protect this beach area, but resulted in the transfer of the coastal erosion problem to the northern beach. In a second attempt to solve this problem, it was adopted a third configuration that apparently had a positive impact on the prevention of the coastal erosion. These three different breakwater configuration scenarios were studied, using a software package that simulates waves, coastal currents and sediment transport, with the specific objectives of studying, testing and finding solutions in order to eliminate the coastal erosion. The second focus of this work is to study the wave climate of the region, through the measurements of a directional wave buoy over a period of three years. For this purpose it was developed a practical wave partitioning method to be applied on the measured directional spectra, in order to more clearly distinguish the characteristics of each wave system that is part of the spectrum. After this step, a comparison was made between the wave climate obtained through the buoy measurements, and the wave climate obtained through the software package, used in the first stage of this work, in order to validate the use of this software as a reliable tool in the study of the coastal erosion impact. The result of this comparison is that the software has a reliable database, but it needs some tweaking to get a better description of the region wave climate.

Au moment de la division cellulaire, l’ADN contenu dans les chromosomes doit être transmis de la cellule mère à chacune des cellules filles. Pour cela l’ADN est d’abord copié (réplication de l’ADN) puis séparé (ségrégation des chromosomes) dans chacune des cellules filles. Chez les eucaryotes, cette séparation se fait au moment de la mitose c’est à dire après que les chromosomes soient complètement répliqués. Chez les bactéries qui en général possède un unique chromosome circulaire, cette ségrégation des chromosome se fait au fur et à mesure de la réplication et deux grands types d’acteurs sont souvent impliqués dans ce processus : Les condensines bactériennes (de type SMC) et les systèmes de partition (ParABS).Les systèmes de partitions sont composés de deux protéines ParA et ParB et de séquences spécifiquement reconnues par ParB nommées parS. Ces séquences sont en nombres variables selon les espèces et sont souvent localisées proche de l’origine de réplication (oriC) sur le chromosome. Pendant ma thèse, je me suis interessée à l’importance de ces séquences et à l’importance de leur positionnement sur le chromosome chez Pseudomonas aeruginosa. J’ai pu montrer qu’un seul site parS suffit pour une ségrégation correcte des chromosomes s’il est situé dans une région s’étendant de -200 à + 450 kb autour d’oriC. Les limites de cette région appelée « zone de compétence » serait liées à la distance oriC-parS et son asymétrie serait due à la présence de l’opéron ribosomique rrnD à 220 kb à gauche d’oriC. En plus de donner une meilleur compréhension de la ségrégation chez P. aeruginosa, cette partie du projet à permis de mettre en evidence un lien entre oriC et sites parS qui pourrait expliquer leurs localisation proches sur le chromosome.Je me suis également interéssée au complexe SMC-ScpAB et à son rôle dans la ségrégtion du chromosome chez P. aeruginosa. J’ai montré que si SMC n’a pas un rôle majeur dans la ségrégation des chromosomes, il est important pour le positionnement du chromosome dans la cellule. J’ai aussi mis en evidence un lien entre SMC et le système ParABS en étudiant l’effet du déplacement d’un site parS sur l’organisation et la ségrégation des chromosomes. / When a mother cell is dividing, DNA inside chromosomes needs to be transmitted to daughter cells. For that, the DNA is copied (replication) and the two copies are separated in each daughter cell (segregation). In eukaryotes this separation occurs during mitosis after complete replication of DNA. In a bacterium, which in general has a unique and circular chromosome, segregation occurs concomitantly with replication and two mains actors are often involved in this segregation: SMC complexes and partition systems (ParABS).A partition system contains 3 elements: two proteins ParA and ParB and DNA sequences named parS. These sequences are highly conserved and are found in variable numbers depending on bacteria. Their chromosomal localization is almost always close to oriC. During my thesis I worked on the importance of these sequences and on the importance of their chromosomal localization for the functioning of ParABS in Pseudomonas aeruginosa.I have shown that one parS site is enough for correct chromosome segregation if it is located between -200 and +450 kb around oriC. Limits of this region called “zone de competence” are probably linked with the distance between oriC-parS. The asymmetry of the “competence zone” is probably due to the presence of a ribosomal operon (rrnD) at -220kb. This part of the project allow us to understand better chromosome segregation in Pseudomonas aeruginosa but also to highlight a fonctionnal link between oriC and parS which can explain why this sequences are located close from each other on the chromosome in lots of bacteria.I also studied the SMC-ScpAB complex and its role in chromosome segregation. For that I analyzed the conformation and segregation of a ∆smc mutant. I highlighted a link between SMC-ScpAB and ParABS system by characterization of mutants with parS displaced on the chromosome.

Maintenance of an intact genome and proper regulation of the genes within are crucial aspects for life. The work of this dissertation has implicated the Drosophila condensin II complex in both processes. Condensin II's ability to reconfigure chromosomes into spatially separated and discrete units is necessary to ensure proper meiotic segregation. When this "individualization" activity fails in a condensin II mutant, chromosomes remain entangled, and either cosegregate or become lost during cell division. This leads to the creation of aneuploid sperm. We have also implicated condensin II as a factor necessary to individualize interphase somatic chromosomes from one another. This is relevant in Drosophila because the association of homologous chromosomes is thought to facilitate gene regulation activity in trans. We speculate that condensin II individualization spatially distances aligned chromosomes from one another and prevents this trans-communication between allelic loci. This is supported first by an increase of homologous chromosome pairing in a condensin II mutant background. Secondly, loss of condensin II leads to elevated production from alleles that are known to depend on pairing for transcriptional activation. These meiotic and interphase condensin II roles support its necessity to Drosophila genome integrity and transcriptional regulation. Given the conservation of condensin from bacteria to humans, it is likely that equivalent or related roles exist in a variety of species.

Un croisement intra-spécifique entre deux accessions d'Arabidopsis thaliana (Sha et Mr-0) a donné 100% d'individus mâles stériles dans la descendance F1 lorsque Sha est utilisé comme parent maternel et Mr-0 comme parent mâle (Sha x Mr-0). Dans le croisement réciproque (Mr-0 x Sha), les individus F1 sont mâles fertiles. Étant donné que l'hérédité du cytoplasme chez Arabidopsis thaliana est maternelle (non Mendélienne), cela indique que cette stérilité mâle résulte d'une interaction entre le cytoplasme de Sha et les allèles nucléaires de Mr-0. Une cartographie génétique d'une population en ségrégation a permis, au cours d’un travail préliminaire à cette thèse (Cezar Sophie Hiard et Cezary Waszczak), de localiser les locus nucléaires sur les chromosomes 1 et 3 ; de plus, la présence des allèles Mr-0 au deux locus est nécessaire pour observer le phénotype de stérilité mâle. Les objectifs de thèse étaient de décrire le phénotype de stérilité mâle, d'identifier les facteurs cytoplasmique(s) et nucléaires, et de commencer l'étude des mécanismes moléculaires sous-jacents à l'origine de cette stérilité mâle. Le clonage positionnel, stratégie adoptée pour identifier les facteurs nucléaires, a permis de diminuer les intervalles aux deux locus et, pour l’un d’entre eux, de pouvoir proposer une approche « gènes candidats ». En parallèle, des croisements réciproques supplémentaires, entre Mr-0 et d'autres accessions que Sha, ont été réalisés et ont permis d’identifier d’autres accessions inductrice de stérilité qui proviennent de la même région géographique que Sha (Asie Centrale) ; la détermination des cytotypes chez les nouvelles accessions testées a montré que la stérilité mâle en F1 apparaît lorsque le parent maternel possède un cytoplasme du même groupe que celui de Sha. Concernant le facteur cytoplasmique inducteur de stérilité, nous avons identifié un seul candidat, l’orf117Sha mitochondrial, qui est spécifique des accessions inductrices de stérilité comme Sha et qui présente beaucoup de similarités avec des facteurs inducteurs de stérilité identifiés dans d’autres systèmes de stérilité mâle cytoplasmique chez les Angiospermes. La caractérisation du phénotype de stérilité mâle par une approche cytologique classique a été réalisée sur des génotypes où les allèles Mr-0 aux locus mainteneurs sont introgressés dans un fond génétique Sha ; selon les génotypes, les allèles mainteneurs Mr-0 sont présents simultanément ou uniquement à l’un des deux locus identifiés, afin de pouvoir observer indépendamment l'influence des allèles Mr-0. Des observations d’anthères prélevées sur ces génotypes et colorées à l’Alexander ont permis de confirmer l’effet des allèles Mr-0 aux locus mainteneurs (introgressés dans un fond génétique homogène) sur la viabilité des grains de pollen, ainsi que le déclenchement tardif de la stérilité mâle nucléo-cytoplasmique au cours du développement pollinique. L’effet, sur la viabilité des grains de pollen, d’autres locus que les locus mainteneurs, appelés locus distorteurs de ségrégation et non liés à la SMNC, a également été observé. De nombreuses incompatibilités génétiques s’expriment dans la F1 Sha x Mr-0 ; elles créent une barrière reproductive post-zygotique en affectant la production de pollen dans la descendance. Le croisement Sha x Mr-0 pourrait révéler un processus évolutif en cours pouvant aboutir à terme à des événements de spéciation au sein d’Arabidopsis thaliana. / The genome of plants is compartmentalized between nucleus and organelles (chloroplasts and mitochondria). These compartments have different inheritance patterns (nuclear genes have Mendelian inheritance; organelles genes are maternally inherited) and this has consequences for their co-adaptation, which is under the influence of two forces: on the one hand, a functional co-adaption whose failure leads to Bateson-Dobzhanski-Muller incompatibilities, on a second hand a genomic conflict, sometimes revealed by nucleo-cytoplasmic male sterility. The wealth of genetic resources at our disposal for Arabidopsis thaliana makes it an interesting model to study the co-evolution between genetic compartments. As part of this problem, this thesis is devoted to a male sterility presenting a nucleo-cytoplasmic determinism and which emerged as a result of a cross between two accessions (Sha x Mr-0) while the reciprocal cross (Mr-0 x Sha) produced male fertile F1 individuals. Results preliminary to this thesis have shown that male sterility results from an interaction between the cytoplasm of Sha and dominant alleles carried by chromosomes 1 and 3. The objectives of this thesis were to describe the phenotype of the male sterility, as well as to identify both cytoplasmic and nuclear factors, and also to start the study of the underlying molecular mechanisms, which are responsible of this male sterility. I followed a strategy of genetic mapping to identify involved nuclear factors by positional cloning. I localized the maintainer locus on chromosome 3 in an interval of 53 kb and began a molecular analysis of this region in the two parental accessions. This now allows a candidate gene approach for this maintainer. I also showed that the maintainer locus on chromosome 1 probably consists of two closely linked loci, whose alleles Mr-0 are both required for the expression of the male sterility. In parallel, reciprocal crosses involving either Mr-0 or Sha with accessions of the collection allowed us to identify at least one other accession with maintainer alleles (Etna-2), and a dozen accessions carrying the male sterility-inducing cytoplasm (all from Central Asia). A comparative analysis of cytoplasmic genomes of Sha and Kz-9, which has a cytoplasm very close to Sha but not inducing sterility, revealed a mitochondrial gene, candidate for male sterility and called orf117Sha. It is specific to accessions inducing sterility and its putative product shows 57% identity and 71% similarity with orf108, a gene involved in cytoplasmic male sterility in alloplasmic Brassicas (Ashutosh et al, 2008 ; Kumar et al, 2012).During the mapping and cytological observations, I have highlighted genetic incompatibilities that cause distortions of segregation through the male descent in the progeny of heterozygous plants. These incompatibilities, probably independent of the cytoplasm, create genetic barriers between the two parental accessions of the cross that I studied. I propose that the cross Sha x Mr-0 reveals an ongoing evolutionary process that can eventually lead to speciation events in Arabidopsis thaliana.

MUC4 is a heterodimeric mucin glycoprotein expressed in the epithelia of tissues. Previous studies in our laboratory demonstrated that MUC4 protein expression is regulated by exogenous growth factors and that MUC4 is found in complex with the receptor tyrosine kinase ErbB2. MUC4 protein expression in airway epithelia was evaluated using molecular biology techniques. The impact of the protein on ErbB2 activation was evaluated post mechanical wounding of airway epithelia, and upon MUC4 RNA silencing. MUC4 levels were increased with exposure to the differentiating agent retinoic acid and decreased upon exposure to epidermal growth factor, a proliferative agent. In the absence of MUC4, ErbB2 phosphorylation was diminished. These results support the hypothesis that MUC4 expression is enhanced during differentiation of epithelia. Furthermore these findings provide evidence for an additional level of ErbB regulation in airway injury and subsequent epithelial wound healing.

Wilting during shelf life is a major cause of postharvest shrink for bedding plants shipped long distances from production greenhouses to retail outlets. The objective of this research was to determine if irrigation at lower, constant substrate moisture content (SMC) during greenhouse production would be a feasible way to acclimate plants for reduced shrinkage during shelf life, while potentially conserving irrigation water. Rooted plugs of Angelonia angustifolia 'Angelface Blue' were grown in greenhouse production until a marketable stage in substrates irrigated at SMC levels of 10, 20, 30, and 40% using a controlled irrigation system. At the end of the greenhouse production stage, plants were irrigated to container capacity and subjected to a simulated shipping environment, in shipping boxes in the dark for two days. After shipping, plants were placed back in the greenhouse and watered minimally to simulate a retail environment. Data was taken at the end of each stage i.e. greenhouse production, simulated shipping, and simulated retail. Parameters measured at the end of the production stage were fresh and senesced flower number, stem number, pre-dawn and mid-day water potential, SPAD meter readings (Experiment 2), and plant height and node number segmented into vegetative, flowering, and bud area. Plant quality was observed and rated. At the end of the simulated retail stage, the same data was taken, along with fresh and dry shoot and root weight. Results indicated that as SMC decreased from 40 to 10%, plants were shorter in height, but had proportional flowering sections (Experiment 1) or more compact flowering sections (Experiment 2). The volume of water received by the 40% SMC plants was three times greater (Experiment 1) and 12 times greater (Experiment 2) than the 20% SMC plants during greenhouse production, and two times greater (Experiment 1) and nine time greater (Experiment 2) during simulated retail. Additionally, the 40% SMC plants used 15 liters (Experiment 1) and 38 liters (Experiment 2) of water during greenhouse production compared to the 20% SMC plants using only three liters in both experiments. During simulated retail the 40% SMC plants used six liters (Experiment 1) and nine liters (Experiment 2) of water while the 20% SMC plants used five liters (Experiment 1) and three liters (Experiment 2) of water. During production, mid-day water potentials decreased as the SMC levels decreased, but at the end of the simulated retail (Experiment 1), the mid-day water potentials were all the same, suggesting plants that were drought stressed during production area were acclimated to lower water levels experienced in retail settings. Overall, the 20% SMC treatment produced the best postharvest quality plant due to reduced plant height without detrimental effects on flowering. The results demonstrate that while conserving water, controlled irrigation at a medium-low SMC can produce high quality plants that have equal shelf life to those that are irrigated at high levels.

Control of mechatronic systems remain an open problem in control theory despite the research work worldwide in the last decade. Uncertainties in mechatronic systems, which includes faults, and disturbance, will often cause undesired behaviours, affecting the systems performances, may lead to the system failure, or even causing safety issues. Control reconfiguration is an active approach in control systems field. However, controller reconfiguration involves changes in its parameters and structure. System stability might not be able to be guaranteed during the parameters tuning, which might cause more damage to system stability, sometimes may cause safety issues. Due the on-line reconfiguration has a scope, during which the system stability can not be guaranteed. This leads that the systems must be turned off during reconfiguration process. In many industrial areas, such as metallurgy, forging, and manufacturing, shutting down the streamline leads to significant levels of lost productivity and unacceptable economic losses. As alternative to control reconfiguration approach, in this thesis two methods are proposed to deal with faults and disturbances. The first method is the fault matrix observer and the second one is the set-point re-planning. The idea of both methods is to compensate the faults and disturbances which affect the system performances without changing the controller structure or controller parameters.