Dissertations / Theses on the topic 'Mécanismes génétiques'
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Omer, Hélène. "Etude de différents mécanismes génétiques associés à l'hyperinvasivité de Neisseria meningitidis." Paris 5, 2011. http://www.theses.fr/2011PA05T003.
Full textNeisseria meningitidis is a commensal of the human nasopharynx which can sometimes cause serious or even deadly diseases. The mechanisms which allow some strains to become hypervirulent are still widely unknown even though various bacterial, human and environmental factors were shown to be involved. For instance a filamentous bacteriophage, the MDA, is significantly associated with strains from hypervirulent complexes. A scientist from the laboratory was accidentally infected with a serogroup A strain isolated from an epidemic in the Gambia in 1983 and cultivated in the laboratory to express the MDA prophage. The genetic and phenotypic differences between the blood culture strain and the infecting strain have been studied. Their genomes have been sequenced, showing the importance of phase and antigenic variations during the infection. This was reflected by heterogeneity in the expressed pili, a modification of the lipooligosaccharide and a variation in the iron acquisition systems from haemoglobin. Even if the amount of bacterial multiplications in the blood was low, the in vivo passage selected genomic modifications directly affecting the bacterial invasivity. This study also showed that the infecting strain contained a second integration of the MDA prophage in its genome. The study of the phage reintegration in the bacterial genome has shown a great variability of expression amongst the different colonies of a same strain. The MDA production depends on stress, a functional piliation machinery and it is regulated by the RecA protein
Lheureux, Fabrice. "Etude des mécanismes génétiques impliqués dans l'expression des séquences EPRVs pathogènes des bananiers au cours des croisements génétiques interspécifiques." Montpellier, ENSA, 2002. http://www.theses.fr/2002ENSA0013.
Full textWu, Yuanfei. "Pathogenèse moléculaire du carcinome hépatocellulaire : rôle de facteurs viraux et mécanismes génétiques." Paris 7, 2003. http://www.theses.fr/2003PA077191.
Full textEngohang, Ndong Jean. "Mécanismes génétiques de l'activation de la pro-drogue éthionamide chez les mycobactéries." Lille 1, 2003. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2003/50376-2003-369.PDF.
Full textAlmahmoud, Iyad. "Étude des mécanismes génétiques de la résistance aux fluoroquinolones chez Legionella pneumophila." Grenoble 1, 2009. http://www.theses.fr/2009GRE10274.
Full textLegionella species cause legionellosis, an acute pneumonia with an 15% mortality rate. Fluoroquinolones are considered as first-line drugs, but treatment failures may occur due to selection of resistant mutants. We studied fluoroquinolone resistance mechanisms in L. Pneumophila by experimental evolution. Eight independent lineages were founded from a common ancestor that was serially propagated in the presence of increasing concentrations of moxifloxacin. We selected resistant mutant strains with low to high levels of resistance to moxifloxacin (2 to 8192 X MIC), due to mutations in the genes encoding type II topoisomerases. High level of resistance was associated to a specific order of mutations, the first one affecting the codon 83 of gyrA. We designed a real-time PCR-based assay to test the presence of this mutation in 385 natural isolates and 78 sputum samples obtained from legionellosis patients at the time of hospital admission and before antibiotic treatment. No mutation was found whatsoever but we can now use this tool to survey the prevalence of fluoroquinolone resistance by using a culture-independent approach, which provides a great advantage for microorganisms with fastidious growth. This will be applied to sputum samples from patients with treatment failures. We tested the impact of the detected resistance mutations on fitness and virulence of L. Pneumophila. Both phenotypes were negatively affected in resistant mutants, but compensation occurred after repeated growth in antibiotic-free medium, thereby suggesting the potential adaptation and maintenance of resistant mutants in natural environments
Roussel, Célia. "Compréhension des mécanismes physiologiques et génétiques impliqués dans l'activité réductrice de Lactococcus lactis." Thesis, Dijon, 2015. http://www.theses.fr/2015DIJOS043/document.
Full textLactic acid bacteria, particularly Lactococcus lactis are used in dairy industry. These bacteria are known to have a reducing activity, indicating their ability to lower the redox potential (Eh) of a medium. L. lactis MG1363 genome encodes several proteins with a CXXC motif, potentially linked with a redox activity. To understand the role of proteins rich in cysteine located at the surface of L. lactis, two approaches were used, one bioinformatics and biochemical another. For bioinformatic approach, interest was focused on two proteins of unknown function and CX2CX10CX2C motif: Llmg_0524 and Llmg_0526. Their corresponding genes form an operon temporarily induces in early growth phase. In these two proteins, the pattern chelate a zinc ion via its cysteine residues. The zinc-cysteine complexe is very stable, it suggests a probable role in protein stability. Data suggest that this operon contributes to the cell wall integrity. The identification of exofacial thiol proteins by a biochemical approach indicates that AhpF is present at the surface of L. lactis. The ahpF gene deletion causes a strong sensitivity to the cumene hydroperoxide, but no sensibility for hydrogen peroxide. In the mutant ahpF incubation with cumene hydroperoxide modified fatty acid proportion, cyclopropanation mechanism thus contributes to the survival in response to oxidative stress. Understanding the lactococci functions involved in the reduction activity allows a better control of redox potentiel in the fermented food production and thus a better control of foodbornes microorganisms in these products. Food-Redox project is financially supported by the French National Research Agency
El, Baidouri Fouad. "Le genre Leishmania : structure génétique et mécanismes d'évolution." Thesis, Montpellier 1, 2012. http://www.theses.fr/2012MON1T028.
Full textParasitic protozoa of the Leishmania genus infect many mammal species throughout the world. Transmitted by insect vectors, these pathogens are endemic in a hundred countries. In humans, the incidence of the disease is estimated at about 2 million new cases each year. Today, multiple issues arise on the modes of reproduction and genetic exchanges among these protozoa. They have implications on evolution, adaptation to new cycles, virulence, specific identification, taxonomy or therapeutic management.In this work, we first aimed at addressing these issues through a comprehensive genetic analysis of all Leishmania species from Eurasia and Africa, using a MLSA (MultiLocus Sequence Analysis)-based approach, from a dataset of more than 220 strains from 43 countries. We then tried to understand the structuration of this controversial group by participating in the isozyme data analysis of more than 2200 strains of viscerotropic Leishmania. Finally, using data from a very small focus of the anthoponotic species Leishmania tropica, we contributed to the analysis of isozyme characterization of this population and to the study of possible transmission cycles.Our results highlight a number of important points. They first show that the different Leishmania species found in Africa and Eurasia are divided into seven distinct groups, partially overlapping the ten species identified so far mainly on biochemical criteria. The multilocus system we developed is more resolutive than that based on isozymes. Implementing a MLST scheme for strain identification could contribute significantly to the therapeutic management of leishmaniases in the Old World. From taxonomic and epidemiological points of view, three viscerotropic species which were separated so far (L. infantum, L. archibaldi, L. donovani) appear to form a genetic continuum (species complex). Our analyzes of isozyme data extended to 2200 strains are in line with this conclusion. Our results also show a remarkable phylogenetic congruence of the seven genomic loci studied by MLSA. This does not support potential genetic exchanges and recombinations between different species, contrary to what was assumed so far. Potentially frequent, inter-specific hybridization would not contribute to the evolution of genotypes and would be a transient and unstable event, unable to settle in genomes. However, it will probably be necessary to explore different models exhaustively before drawing definitive conclusions.Finally, the study of correlations between geographic distance and genetic structuration revealed the focus of many genotypes but also a very high dispersion of some others, even if no convincing hypothesis can be made to explain such differences. In the same way, our analysis of isozyme data of L. tropica strains from the same Palestinian micro-focus seems to show an intra-specific heterogeneity which could be due to differentiated parasitic cycles, despite the geographical proximity
Laribi, Mohamed Amine. "Contribution à la synthèse des mécanismes plans et spatiaux et de robots parallèles par une méthode évolutionnaire." Poitiers, 2005. http://www.theses.fr/2005POIT2342.
Full textThe traditional techniques of synthesis of mechanisms are still limited from application and performances point of view. The experiment of the designer still the essential talent to solve this kind of problem. For this purpose, we propose to develop tools for synthesis of plane and spatial mechanisms and parallel robots by an evolutionary method. The first part is interested in the synthesis of the plane and spatial mechanisms. The new suggested modeling uses the Denavit-Hartenberg parameter. This parameter setting makes easily and possible the study of the four families of mechanisms that we identified. They are solved by an optimization technique based on a combine between a genetic algorithm and a fuzzy logic controller. An application of a spatial mechanism is also developed, which we proposed, like anti pressure ulcers device. The second part is dedicated to the analysis and the dimensional synthesis of the DELTA robot for a prescribed workspace. We introduce the concept of power of a point compared to a surface, used in the formulation of the problem of synthesis. In fact, this approach rests on a process of optimization genetic adapting to the various criteria of synthesis
Rhoné, Bénédicte. "Etude de mécanismes génétiques impliqués dans l'adaptation climatique de populations expérimentales de blé tendre." Phd thesis, AgroParisTech, 2008. http://pastel.archives-ouvertes.fr/pastel-00003822.
Full textBébéar, Cécile. "Mécanismes génétiques de la résistance aux fluoroquinolones liée à la cible chez Mycoplasma Hominis." Bordeaux 2, 1998. http://www.theses.fr/1998BOR28553.
Full textDenoyelle, Laure. "Mécanismes génétiques et épigénétiques sous-jacents aux relations phénotype - environnement chez les petits ruminants." Thesis, Université Grenoble Alpes, 2020. http://www.theses.fr/2020GRALV045.
Full textOrganisms can be confronted with more or less important variations in their environment (climate, health, etc...). In response to these variations, three types of mechanisms can be put in place to adjust their phenotype with the environment: choice of a favorable habitat, adaptation and acclimatization. In the case of domestic animals, the choice of habitat is not possible, but the last two mechanisms can be revealed by studying the presence of respectively genetic and epigenetic markers in the genome of individuals. The aim of this thesis was to highlight these two types of mechanisms in small ruminants (sheep and goats) in relation to the breeds history and their environment.First, we analyzed whole genome data to search selection signatures in 11 French goat breeds. On one hand, this analysis allowed us to explore their histories, to understand possible crossbreeding between them and to compare these results with the historical data collected. On the other hand, selected genes related to agronomic traits of interest such as milk production (21 genes), reproduction (14 genes), immunity (11 genes), as well as morphological traits specific to the breeds studied (28 genes) were highlighted.In a second step, we studied the two types of mechanisms in Moroccan goats and sheep which were chosen to form two groups at each end of a temperature variation gradient. The analysis of genetic differences between the two groups, for each species, allowed to locate selected regions in relation to genes involved in environmental perception (5 genes), immunity (4 genes), reproduction (8 genes) and production (11 genes). We have also sequenced regions of the genome bearing methyl groups in these same animals. Analysis of the differentially methylated regions (DMRs) between the two groups allowed to find 2 DMRs (one in each species) in relation, among other things, to milk quality and production. This study of adaptation and acclimatization mechanisms in Moroccan small ruminants is the first to look for epigenetic marks in relation to the environment in farm animals and to compare them with genetic marks present in these same animals. Based on our results, we hypothesize that temperature variation could have two types of effects on animals that could impact the biological pathways we detected. A first effect, direct, which would influence the thermoregulation mechanisms, and a second effect, indirect, in relation to the quantity and quality of available food resources. The comparison between the two mechanisms, and the two species, allowed to find similar impacted biological pathways, but no gene in common.These results show the role of genetic and epigenetic mechanisms in the adjustment of phenotypes to the environment. In a context of climate change, it seems important to take them into account to develop breeding strategies related to these variations
Niyitegeka, David. "Composition de mécanismes cryptographiques et de tatouage pour la protection de données génétiques externalisées." Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2020. http://www.theses.fr/2020IMTA0225.
Full textNowadays, cloud computing allows researchers and health professionals to flexibly store and process large amounts of genetic data remotely, without a need to purchase and to maintain their own infrastructures. These data are especially used in genome-wide association studies (GWAS) in order to conduct the identification of genetic variants that are associated with some diseases. However, genetic data outsourcing or sharing in the cloud induces many security issues. In addition, a human genome is very sensitive by nature and represents the unique biological identity of its owner. The objective of this thesis work is to protect genetic data during their sharing, storage and processing. We have developped new security tools that are based on watermarking and cryptographic mechanisms, as well as on the combination of them. First, we have proposed a privacy-preserving method that allows to compute the secure collapsing method based on the logistic regression model using homomorphic encryption (HE). To overcome the computational and storage overhead of HE-based solutions, we have developed a framework that allows secure performing of GWAS for rare variants without increasing complexity compared to its nonsecure version. It is based on several security mechanisms including encryption. In parallel of these works, we have exploited the semantic security of some HE schemes so as to develop a dynamic watermarking method that allows integrity control for encrypted data. At last, we have developed a robust watermarking tool for GWAS data for traitor tracing purposes
Tran, Ngoc Phuong. "Mécanismes génétiques et biochimiques impliqués dans la réponse au stress acides phénols chez Bacillus subtilis." Dijon, 2008. http://www.theses.fr/2008DIJOS016.
Full textThe aim of this work was to characterize the genetical and biochemical mechanisms involved in the PASR, the phenolic acid stress response induced by phenolic acids in the two Gram(+) bacteria Bacillus subtilis and Lactobacillus plantarum. It also focused on identifying and characterizing PadR, the negative transcriptional regulator involved in this response. Several strategies and techniques of molecular and cellular biology, including random transposon mutagenesis and gene deletion/complementation, were performed to elucidate the mechanisms. Qualitative and quantitative characterizations of the DNA locus involved in the regulation the padC gene expression, a key of the PASR, were achieved by quantification of qRT-PCR, by site-directed mutagenesis of the PadR regulated padC gene promoter to identify the operating sequence, and by error-prone PCR mutagenesis on the padR gene to identify essential amino acid residues. This work coupled with heterologous expressions of the PASR genes in Escherichia coli and in-vitro binding assay (EMSA) and DNAseI foot printing allowed us to elucidate the main component of the PASR
Hautefort, Aurélie. "Etude des mécanismes inflammatoires, génétiques et épigénétiques impliqués dans la physiopathologie de l'hypertension artérielle pulmonaire." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS278.
Full textPulmonary arterial hypertension (PAH) is characterized by a progressive pulmonary arterial obstruction due to pulmonary vascular remodeling of distal arterioles as well as abnormal vasoconstriction. This project allowed to study three biological process clearly establish to be implicated in physiopathology of PAH.The first project demonstrated a dendritic cells dysfunction and a Th17 immune polarization of idiopathic PAH patients.The objective of the second project was to study the epigenetic variations in pulmonary endothelial cells (PEC) through a specific pattern of DNA methylation. We identified clusters of probes that discriminates controls and PAH patients. During bioinformatics study, ABCA1 (ATP binding cassette 1) gene was emphasized. Alteration of ABCA1 expression predicted during bioinformatics study has been validated in human and in monocrotaline rat model.The last project described the validation of a new PAH model by a hemodynamic, histological, vascular, molecular and electrophysiological characterization of heterozygous rat mutated to Bmpr2 gene. Whole functional and molecular dysregulation define this animal model like a useful tool in the study of BMPRII signaling alteration in PAH physiopathology
Lainé, Régis. "Contribution à la conception de cellules robotisées : une approche basée sur les algorithmes génétiques." Poitiers, 2004. http://www.theses.fr/2004POIT2323.
Full textThis thesis deals with the kinematic synthesis problem of industrial robots. It presents an optimization method based on a genetic algorithm, which led to the implementation of a design module, in the CAD-Robotics SMAR system developed at the Laboratoire de Mécanique des Solides. This method determines automatically well adapted geometrical parameters of a robot (kinematic architecture, dimensions and the robot placement) for a given task and an objective function. The function depends on three homogenized coefficients which measure: the distance between the joint values and the joint limits of the robot, the necessary volume of the configuration space to achieve the task and the robot size. The geometrical parameters are determined so that the task is accessible continuously without collision with the environment. As illustration, several examples present the proposed method of kinematic synthesis. The results show that the method is effective, robust and fast
Sutera, Vivien. "Francisella et antibio-resistance : aspects génétiques, phénotypiques et cliniques." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAV064/document.
Full textFrancisella tularensis is a gram-negative facultative intracellular bacterium, causing tularemia. This zoonosis is mainly related to two subspecies: F. tularensis subsp. tularensis (type A) and F. tularensis subsp. holarctica (type B) in North America and throughout the Northern Hemisphere, respectively. Infections with this second subspecies, less virulent than the first one, predominantly induce glandular clinical forms of mild to moderate severity. Their treatment is based on antibiotherapy using a fluoroquinolone or a tetracycline. The use of aminoglycosides is reserved for severe clinical forms. The lymph nodes infection, however, often become chronic (20 to 40% of cases), despite administration of an appropriate antibiotic treatment.The aim of this study was to verify the hypothesis of the emergence of bacterial resistance in Francisella, which could explain treatment failures. It is based on the development and study of an in vitro evolutionary experiment of the bacterium in the presence of ciprofloxacin, a fluoroquinolone. Our work confirmed the bacterium's ability to evolve towards a high-level of resistance to fluoroquinolones, this evolution being correlated with the accumulation of mutations in the genes encoding for type II topoisomerases. In addition, we observed in all strains of F. tularensis subsp. holarctica resistant to fluoroquinolones at a clinically significant level, the presence of mutations altering the GyrA subunit of DNA gyrase at amino acids positions 83 and 87. The research of this marker in clinical samples from patients with treatment failure following appropriate antibiotic treatment was however unsuccessful.After checking the action of antibiotics on bacteria internalized in the intracellular compartment in fibroblast cells, we looked for other mutations induced during the evolution of Francisella to resistance to fluoroquinolones. This study unveiled the involvement of several transmembrane transport systems in antibiotic resistance. We also revealed the existence of a second major target involved in Francisella iron metabolism. The alteration of this target (FupA/B), in addition to being associated with an increase in fluoroquinolone resistance, is correlated with a sharp decrease in the ability of the bacteria to multiply in phagocytic cells
Hussein, Mourad. "Caractérisation des mécanismes cellulaires, génétiques et épigénétiques de la différenciation terminale des lymphocytes B chez l’homme." Thesis, Rennes 1, 2013. http://www.theses.fr/2013REN1S198.
Full textWithin the past few years there has been a significant increase in the knowledge of B cell physiology in vivo and their differentiation into plasma cells through the implementation of murine models and intravital imaging. However, the transposition of this knowledge from mouse to man raises difficulties such as the lack of tools available to visualize the ongoing events in human lymphoid organs. In order to overcome this issue, we have developed in our laboratory, a two-step in vitro model allowing naive B cell differentiation into plasma cells. This model is particularly suitable for studying the induction of signaling pathways, transcription factors and major cellular processes such as proliferation or programmed cell death. Using this model, we conducted two studies on B cell differentiation in the germinal center: (i) phenotypic and functional characterization of cell populations generated in vitro. This study involved a transcriptomic approach which identified and compared the expression profile of specific genes and their biological functions within each of these differentiated populations. Specifically, we focused on the expression and activity of the AID enzyme through the measurement of somatic hypermutation frequency at each stage of differentiation. (ii) The study of cellular (cell cycle, apoptosis), genetic and epigenetic mechanisms leading to the transition of the germinal center B cells into plasmablasts. This study allowed us to characterize a founder cell population of the in vitro generated plasmablasts. In addition, we have highlighted the importance of DNA methylation, in particular 5- hydroxymethylation in controlling terminal B cell differentiation
Sorin, Céline. "Approches génétiques et physiologiques de la rhizogenèse adventive chez Arabidopsis : vers une meilleure compréhension des mécanismes régulateurs." Paris 11, 2004. http://www.theses.fr/2004PA112098.
Full textAdventitious rooting is essential for propagation of woody species and for adaptation to particular environmental conditions. It is a complex process affected by multiple factors like auxin and light. It is also genetically controlled but the molecular mechanisms involved are unknown. To obtain insight into those mechanisms, a. Thaliana mutants were utilised for a series of genetic and physiological experiments. The importance of auxin and light in the regulation of adventitious rooting was demonstrated by the characterisation of superroot (sur1 and sur2) mutants that spontaneously make adventitious roots, and argonaute 1 (ago1) mutants that are barely able to make adventitious roots. We have shown that a mutation in ago1 disrupt auxin homeostasis and light transduction pathways in the apical part. This is correlated to adventitious rooting defect. Proteomics and gene expression analysis at the transcriptional level allowed us to propose candidates genes potentially involved in adventitious rooting or in the control of auxin homeostasis
Pons, Marine. "Identification de facteurs génétiques impliqués dans les mécanismes d'autorégulation de la protéine TDP-43 dans la drosophile." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMR040.
Full textTDP-43 is a DNA/RNA binding protein that plays an important role in RNA metabolism. In the physiological state, strict control of its expression levels is critical for cell function and survival. TDP-43 expression is tightly regulated through an autoregulatory negative feedback loop. This protein has been identified as the principal component of the inclusions observed in a majority of patients with Amyotrophic Lateral Sclerosis (ALS) or FrontoTemporal Lobar Degeneration (FTLD). To date, more than 50 missense mutations of the TARDBP / TDP-43 gene have been described in FTLD / ALS patients, demonstrating the key role of TDP-43 in these neurodegenerative pathologies. However, the functional consequences of TDP-43 mutations are not completely determined. Several studies suggest that high accumulation levels of TDP-43 may participate in pathophysiological mechanisms. The modulation of the production cycle of TDP-43 may therefore provide a new therapeutic strategy. The main goal of this research project was to identify genetic modulators of TDP-43 production by using a novel transgenic Drosophila model mimicking main steps of TDP-43 the autoregulatory mechanism. We identified several splicing factors, including SF2, Rbp1 and Sf3b1, as genetic modulators of TDP-43 production. We have also shown that modulation of TCERG1 expression levels affect TDP-43 production levels in flies. Finally, we found that FTLD/ALSlinked TDP-43 mutations do not alter TDP-43’s ability to self-regulate its expression and consequently of the homeostasis of TDP-43 protein levels
Reinhardt, Anita. "Résistance aux fluoroquinolones liée à la cible chez mycoplasma gallisepticum : : sélection de mutants et analyse des mécanismes génétiques." Rennes 1, 2002. http://www.theses.fr/2002REN1A002.
Full textGuilloteau, Bruno. "Étude des mécanismes de l'inflammation au travers de manipulations génétiques de NFKB dans l'endothélium vasculaire de la souris." Nantes, 2002. http://www.theses.fr/2002NANT25VS.
Full textVascular endothelium is an anticoagulant and anti-inflammatory barrier that can modify its phenotype to evoke an inflammatory environment in response to pathophysiological stimuli such as endotoxin, cytokines, and immunological insults. Endothelial cell (EC) activation implicates de novo expression of genes such as those encoding adhesion molecules, chemokines and procoagulant factors. NFkB regulates the induction of most of these gene s and specific inhibition of this transcriptional factor in vivo would provide a useful approach for a study of its role in gene expression in EC during endothelial cell activation. We then have generated Tie2 IkBa transgenic mice to over-express a mutant mIkBa protein (Ser32/36 mutated) in the vascular endotheliurn. However, the lethal character observed in RelA and IKK2 knock-out mice led us to create an inducible expression system for mIkBa using the Cre/loxP recombination system. The Cre recombinase protein is known to excise DNA, which is flanked by loxP sequences. The fusion of this enzyme to a mutated ligand-binding domain of the human progesterone receptor (PR) results in a RU486-dependent Cre-recombinase Cre-PR, which is activated by RU486 but not by endogenous progesterone. Generated Tie2 CrePR transgenic mice will be crossed with a second mouse strain transgenic for mIkBa in which the expression is disrupted by the insertion of a loxP-flanked-S TOP sequence. The excision of the insertion can be induced by administration of RU486 to these double transgenic mice, therefore inducing activation of mIkBa. This inducible system will be used if any lethal character is observed during reactivation of mIkBa by using a Cre deleter. The expression of the mIkBa protein is observed specifically after Cre-mediated recombination in all vascular tissues tested. Transgenic mice for mIkBa show an Endothelial cell-specific inactivation of NFkB and present a hypersensitivity to TNF, which leads to hemorrhage-mediated death
El, Halmouch Yasser H. "Recherche de mécanismes de résistance à l'Orobanche chez des génotypes de tomate : aspects histologiques, physiologiques, moléculaires et génétiques." Nantes, 2004. http://www.theses.fr/2004NANT2045.
Full textIn the Mediterranean area and the Nile Valley broomrape, a parasitic plant, causes severe yield losses in tomato fields. In order to find broomrape resistant tomato genotypes a screening of numerous wild, varieties and introgression lines was carried out, first under greenhouse conditions, then in an in vitro co-culture. One of the most interesting genotype, Lycopersicon pennellii, produces root exudates which inhibit broomrape germination and induce necrosis of the parasitic tubercles. Host responses involved cell wall thickening lignin deposition and xylem vessel occlusion. The expression of some genes from the lignin biosynthesis pathway was shown to be rapidly induced in L. Pennellii infested by broomrape
Jourdy, Yohann. "Détermination des mécanismes physiopathologiques d'anomalies rares de la coagulation à l'aide de modèles in vitro et d'approches génétiques innovantes." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1316/document.
Full textInherited coagulation disorders are caused by a large number of genetic abnormalities. However, the determination of the clinical impact for some of these genetic variations is challenging for the molecular biologist.In a first part, we characterized large genomic rearrangements in haemophilia patients using cytogentic microarray analysis. In a first study, we delineated six F9 complete deletions in order to investigate genotype/phenotype correlations. We identified SOX3 as a candidate gene for intellectual disability (ID) found Haemophilia B patients. In a second study, we described five complex Xq28 rearrangements in Haemophilia A (HA) patients. We showed that several F8 neighbouring genes are involved in these rearrangements and some of these genes are involved in other pathologies such as ID, physical abnormalities and cardiovascular disease. Such investigations would be particularly useful for genetic counseling in female carriers to assess the risk of transmitting haemophilia associated with other diseases.In a second, we developed a minigene assay to characterise putative splice site mutations in F8 and we showed that 21 out of the 26 variations studied are associated with splicing defect.In the third part, we described two original molecular mechanisms leading to coagulation disorders. In a first case, we reported a recurrent deep intronic deletion in mild HA. We gave some evidences that this deletion promoted AluY exonization in F8 transcrits. Due to its high prevalence (6.1%), this deletion must be investigated in all patients with mild HA in whom no mutation has been detected by standard genetic analysis. In the second study we investigated the mechanism responsible for bleeding tendency in patient carrying the THBD c.1611C>A and having high levels of soluble thrombomoduline (TM). We showed that a higher sensitivity of the mutated TM to the proteolysis by metalloproteases and a defect of TM synthesis seemed responsible for TM shedding
Malgorzata, Rak. "Modélisation chez la levure de déficiences en ATP synthase responsables de maladies chez l'homme : mécanismes moléculaires et suppresseurs génétiques." Bordeaux 2, 2007. http://www.theses.fr/2007BOR21430.
Full textBoudsocq-Silvestre, Anne. "Résistance aux benzimidazoles des communautés de nématodes parasites du tractus digestif des petits ruminants : mécanismes génétiques et facteurs environnementaux." Tours, 2000. http://www.theses.fr/2000TOUR3805.
Full textDumontet, Typhanie. "Rôle de la signalisation PKA dans la zonation de la glande surrénale : modèles génétiques murins et mécanismes post-traductionnels." Thesis, Université Clermont Auvergne (2017-2020), 2017. http://www.theses.fr/2017CLFAC030.
Full textPrimary Pigmented Nodular Adrenal Disease (PPNAD) is the most frequent endocrine manifestation of a rare, dominantly inherited multiple endocrine neoplasia syndrome, the Carney Complex. These bilateral hyperplasia are associated with inactivating mutations of PRKAR1A, the gene encoding the R1 regulatory subunit of cAMP-dependent protein kinase (PKA). These benign tumors lead to constitutive activation of PKA, responsible for an ACTH-independent hypertcortisolism (Cushing's syndrome), associating various comorbidities such as central obesity, diabetes, osteoporosis, mood disorders or cardiovascular complications. However, the mechanisms of tumorigenesis remain poorly understood. In order to evaluate the consequences of activation of PKA signaling on tumor induction and endocrine activity, the team previously generated a model of transgenic mice reproducing the inactivation of Prkar1a in the adrenal cortex. These mice develop bilateral hyperplasia composed of cells with fetal characteristics naturally absent from an adult adrenal gland.The general objective of this thesis was to identify the origin of the cells constituting this hyperplasia found in the internal cortex of the mutant mice. We used a genetic approach of cell lineage to trace the origin of these tumors after deletion of Prkar1a in the precursors of the adult or fetal cortex.The results show that activation of PKA signaling in the adult cortex is sufficient to promote the development of adrenal hyperplasia associated with Cushing's syndrome. The ablation of Prkar1a in the precursors of the fetal cortex does not lead to any endocrine or tumor abnormalities. On the contrary, activation of PKA signaling in the adult cortex promotes centripetal cell renewal, fasciculata identity and its conversion into reticularis identity in the internal part of the gland. The activation of PKA signaling, together with cortical growth, therefore appears to be a possible motor of adrenarche, normally restricted to human and some primates.Transcriptomic analysis of the adrenals and cell lineage experiments show that female predisposition to Cushing's syndrome and development of "pseudo-reticularis" hyperplasia may be based on sexual dimorphism of progenitor cell recruitment capacities and on metabolism of cholesterol.In parallel, the exploration of the mechanisms leading to the inappropriate presence of "pseudo-reticularis" cells led us to test the involvement of SUMOylation in the observed zonation defects. Our results show that the activation of PKA signaling in vitro and in vivo exerts a global hypoSUMOylation, of transcriptional origin. In agreement with this effect, the nodules present in patients with PPNAD are hypoSUMOylated. Finally, we show in both species a regionalized SUMOylation gradient in the cortex that suggests the implication of this modification in the zonation of the adrenal gland
Maupetit, Mehouas Stéphanie. "La pseudohypoparathyroïdie de type 1b, un modèle d’étude des mécanismes d’empreinte au locus GNAS." Paris 5, 2011. http://www.theses.fr/2011PA05T025.
Full textGNAS is a complex locus submitted to genomic imprinting: the expression of transcripts is restricted to one allele in a parent of origin manner depending of the methylation status of their promoter. A rare disease, pseudohypoparathyroidism type 1b (PHP1b) is characterized by a loss of genomic imprinting, characterized by methylation abnormalities of the locus and leading to abnormal expression of transcrits. The objectives of my work was: i) to characterized the epigenetic defect at the GNAS locus in a cohort of patients affected with PHP1b. Three sub-‐clusters of PHP1b have been identified on the basis of their methylation pattern at the GNAS locus, leading to the hypothesis that distinct molecular mechanisms lead to distinct methylation pattern in PHP1b patients. Ii) to studied molecular mechanisms, which control the methylation at the GNAS locus. We tested the hypotheses that PHP1b could be due at least in some cases, to an epigenetic mosaic. The confirmation of this epigenetic mosaicism is demonstrated by the analysis of the methylation pattern at the GNAS locus in clonal cells obtained from cultured fibroblasts of a patient affected with Spor-‐PHP1b. Furthemore, we hypothesized that a putative global imprint disorder could be involved in some PHP1b patients. We investigate the methylation pattern of 6 imprinted loci in Spor-‐PHP1b patients. In collaboration with Irene Netchine’s team (Inserm UMR-‐S938 Team 4), we found 5 out of 63 PHP1b patients present with an incomplete loss of imprinting at several imprinted loci. A trans acting factor may be responsible of these incomplete losses of imprinting at several imprinted loci
Da, Rosa Rafael. "Mécanismes moléculaires et bases génétiques de la capacité de survie des huîtres Crassostrea gigas à des vibrioses : une exploration transcriptomique." Thesis, Montpellier 2, 2011. http://www.theses.fr/2011MON20101/document.
Full textThe objectives of this thesis were to explore the molecular mechanisms and genetic bases involved in Crassostrea gigas oyster survival to infectious diseases, considering two Vibrio strains (V. splendidus LGP32 and V. aestuarianus LPi 02/41) pathogenic for oysters which have been shown to be involved in C. gigas mass mortalities in France. By the Digital Gene Expression transcriptomic approach, we have identified some genetic components implicated in a successful response and survival to virulent Vibrio infections. Oyster survival capacity is reflected by the basal expression of a selected combination of hemocyte genes, a 14-gene survival signature, and by the induction of some cellular functions during the oyster immune response. A detailed transcriptomic analysis at individual level revealed an extraordinary interindividual polymorphism in basal gene expression, including cases where some transcripts are fully absent. In order to understand this striking variability in gene expression, we have focused on the characterization of a novel family of antimicrobial peptides (AMP) in C. gigas oysters, the big defensins (Cg-BigDef). We have shown that Cg-BigDef is an AMP family, composed of three members, and diversified in terms of sequences but also in terms of genomic organization and regulation of gene expression. Each Cg-BigDef form is encoded by a distinct gene that follows different patterns of gene regulation upon Vibrio infection. Interestingly, some oysters were shown do not express simultaneously the three Cg-BigDef forms or any Cg-BigDef. We demonstrated that the absence of Cg-BigDef basal gene expression is likely due to the absence of the Cg-bigdef gene in oyster genome. This is the first evidence in an invertebrate of a presence/absence variation (PAV) of genes, a phenomenon that could be associated to a susceptibility to infectious diseases
Sarnowski, Chloé. "Etudes d'association prenant en compte des mécanismes complexes : application à l'asthme." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS232.
Full textAsthma is a chronic airway inflammatory disease. It is a complex and heterogeneous disease with a wide spectrum of clinical manifestations in which the age of onset plays an important role. Asthma results from many genetic and environmental factors and from interactions between these factors.To identify new susceptibility genes to asthma and allergic diseases, we performed genome-wide association studies and positional cloning studies, while taking into account complex mechanisms: 1) parental imprinting, 2) heterogeneity of the disease and 3) gene-by-environment interactions.We first conducted a positional cloning study for asthma-plus-rhinitis in European families of four independent studies (770 families ascertained through an asthmatic and including 3200 subjects) while taking into account parent-of-origin effects. The integration of genetic and epigenetic data enabled us to identify that the effect of a paternally inherited genetic variant on the combined phenotype asthma-plus-rhinitis was mediated by a differentially methylated CpG site within MTNR1A gene. We then took into account the variability of age-of-asthma onset in the disease modeling using survival analysis methods and conducted a meta-analysis of genome-wide association studies of time-to-asthma onset in nine European populations (5,462 asthmatics and 8,424 non-asthmatics). We identified a new asthma susceptibility locus in 16q12. We also showed that genetic variants of 9p24 and 17q12-q21 regions were associated with early-onset asthma while 16q12 variants were associated with later-onset asthma. Finally, we performed a meta-analysis of five genome-wide interaction studies of time-to-asthma onset with early-life tobacco smoke exposure (3,643 exposed and 5,275 unexposed). We showed that the effect of genetic variants of 9p24 and 17q12-q21 regions on time-to-asthma onset was increased by early-life tobacco smoke exposure.Studying complex mechanisms in genetic studies led to identify new asthma susceptibility genes and to better understand the pathophysiological mechanisms underlying asthma and its variable expression throughout life
Bonneau, Manon. "Bases génétiques et mécanismes cytologiques à l'origine de la diversité de l'incompatibilité cytoplasmique induite par Wolbachia chez le moustique Culex pipiens." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTG053/document.
Full textWolbachia are intracellular alpha-proteobacteria vertically transmitted from mothers to their offspring through oocytes. As a consequence of this transmission mode, reproductive manipulation strategies that promote bacteria spread in host populations have been selected. The most common manipulation used by Wolbachia is called cytoplasmic incompatibility (CI). CI occurs when infected males mate with uninfected or incompatible Wolbachia-infected females and results in the death of offspring before hatching. CI is generally conceptualized as a mod/resc or toxin/antidote model in which paternal Wolbachia would introduce a toxin (mod function) in sperms which would, after fertilization, induce embryonic death unless an antidote produced by maternal Wolbachia in the egg counteracts its effect (resc function). A to date unique diversity of CI phenotypes has been described in the mosquito species Culex pipiens. This diversity is based solely on the diversity of Wolbachia strains hosted by C. pipiens. In this PhD, we conducted, in C. pipiens, the first study of the cytological mechanism behind embryonic mortality in CI crosses. We showed that paternal chromatin condensation and segregation defects during the first embryonic division were responsible for embryonic death in all CI crosses. These CI defects were the only ones observed indicating that the diversity of CI phenotypes in C. pipiens is not based on a diversity of cellular mechanisms. We then studied the cidA/cidB operon in several wPip strains as the functional involvement of this operon in CI was recently demonstrated in Drosophila. We showed that this operon is amplified and polymorphic in all genomes of sequenced wPip. Investigation of cidA/cidB variants in Wolbachia genomes infecting natural populations of C. pipiens, using more than 250 isofemale lines, enabled us to reveal a robust association between cidB variations and change in mod phenotype. In addition, the presence of an ubiquitous cidA variant supports the role of this gene in the resc function. In C. pipiens, the cidA/cidB operon, through its amplification and diversification, is involved in the CI phenotypes diversity and would operate as a toxin-mod / antidote-resc system: cidB being involved in the mod function and cidA in the resc function
Burin, des Roziers Cyril. "Nouveaux mécanismes génétiques expliquant les vitréorétinopathies héréditaires et génération d’un modèle murin de la maladie de Wagner par approche CRISPR/Cas9." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCB162/document.
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Comuce, Maguy. "Caractérisation expérimentale et détermination des paramètres cinétiques de la décomposition thermique du polyméthracrylate de méthyle." Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2010. http://www.theses.fr/2010ESMA0020.
Full textThe achieved work is part of the project "Compfeu" of the National Research Agency, which aims to provide models for simulating of the thermal decomposition of the main materials of the housing environment in case of fire. The present study aims to develop a pyrolysis model of the polymethylmethacrylate (PMMA). Our working approach is innovative in the international community, because it relies on a multi-scale approach, taking into account the evolution of the thermal, physical and chemical properties during the decomposition of the material. Our work was to know the physicochemical properties of our material. The study of the thermal decomposition of the PMMA under inert and oxidizing atmospheres was performed on the scale of the particle by means of differential scanning calorimetry, through thermogravimetric analysis coupled with various analytical devices for different heating rates. The thermal decomposition of PMMA was completed by a study on the scale of the material using the cone calorimeter, coupled with an analytical chain. The study, on the scale of the particle, has allowed us to propose a mechanism of thermal decomposition of PMMA in an inert atmosphere and under oxidizing atmosphere. The rate of each reaction mechanism is described by the Arrhenius law. The determination of these kinetics parameters and stoichiometric coefficient was performed by the optimization method of genetic algorithms
Verrier, Eloi. "Bases génétiques de la résistance aux rhabdovirus et réponse cellulaire chez la truite arc-en-ciel : importance des mécanismes de défense innés." Phd thesis, AgroParisTech, 2013. http://pastel.archives-ouvertes.fr/pastel-00914894.
Full textBouvenot, Typhanie. "Nouvelles perspectives sur les mécanismes génétiques impliqués dans la propagation de la peste par les puces grâce à l’utilisation de la bioluminescence." Thesis, Lille 2, 2020. http://www.theses.fr/2020LIL2S020.
Full textThe agent of the plague, Yersinia pestis, obstructs the flea's digestive tract to be transmitted byfleas. Here, we sought to identify and study the role of new Y. pestis genes involved in theproduction of a transmissible infection in fleas. To this end, we developed a bioluminescencebasedapproach and employed it to investigate the mechanisms of pathogenesis at anunprecedented level of detail. Notably, we used our method to screen a library of mutants (eachlacking one or more of the genes previously identified as over-expressed in fleas) that wegenerated. Our screening listed several new and potentially important factors needed for fleabornetransmission of Y. pestis. Among them is LipB that catalyzes the first step of lipoatesynthesis (a cofactor covalently attached to at least three central metabolism enzymes). Oursubsequent studies have also revealed that the second and last enzyme of the lipoate biosynthesispathway, LipA, but also the lipoate ligase LplA (attaching lipoate scavenged from the environmentto apoenzymes) are also required to produce a transmissible infection in fleas. Thanks tobacteriological, microscopic and biochemical approaches carried out in vitro, ex-vivo and in vivo,we have revealed that bot the lipoate biosynthesis pathway and the lipoate scavenge pathway areinvolved in the colonization of the insect's proventriculus and midgut. Interestingly, we alsorevealed the salvage pathway’s enzyme LplA enhances the first step in lipoate biosynthesis duringforegut colonization but not during midgut colonization thanks to its octanoate activity. Lastly, wefound that Y. pestis primarily uses lipoate provided by digestive proteolysis (presumably as lipoylpeptides) rather than free lipoate in blood, which is quickly depleted by the vector. Thus, spatialand temporal factors dictate the bacterium’s lipoylation strategies during an infection, andreplenishment of lipoate by digestive proteolysis in the vector might constitute an Achilles’ heel thatis exploited by pathogens
Delaroque, Aurélie. "Élaboration d’un outil numérique pour la réduction et l’optimisation des mécanismes cinétiques pour les systèmes de combustion." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS417.
Full textIn the modeling of a combustion process, obtention of global data such as flame speed can, under certain circumstances, be achieved through extremely reduced mechanisms. On the contrary, prediction of detailed data such as polluant species requires the use of detailed kinetic mechanisms involving many chemical species. Due to the size and to the presence of many differents time scales, the integration of those models to complex numerical simulations is a non trivial task. A reduction tool based on Directed Relation Graph and sensitivity analysis methods is proposed to tackle this issue. Reduced mechanisms fitting user defined tolerances for quantities of interest such as global (flame speed, ignition delay, etc) and detailed data (concentration profiles) are automatically generated. The reduction process is paired up with an optimisation of reaction rates through a genetic algorithm to make up for the error induced by the loss of information. This process can use both numerical and experimental reference entries. The complete numerical tool has been tested on several canonical configurations for several fuels (methane, ethane and n-heptane) and reduction rates up to 90% have been observed
Cuisset, Thomas. "Variabilité de réponse au clopidogrel : bases biologiques, mécanismes, conséquences cliniques et alternatives thérapeutiques." Thesis, Aix-Marseille 2, 2010. http://www.theses.fr/2010AIX20694/document.
Full textAntiplatelet therapy is the cornerstone therapy for patients admitted for acute coronary syndrome and/or undergoing percutaneous coronary intervention. Dual antiplatelet therapy with aspirin and clopidogrel is now the gold standard therapy for these patients. In spite of this effective association, recurrent events still occur and low response to clopidogrel has been proposed as one of the responsible factors. Indeed, numerous biological studies have described a broad interindividual variability of platelet response to clopidogrel, assessed with various platelet function tests such as light transmittance aggregometry, VASP phosphorylation index and the bed-side Verify Now assay. Mechanisms underlying this variability of response remain unclear and probably multifactorial, but factors have been clearly identified: genetic polymorphisms, medications interactions and clinical factors (diabetes, weight…). More recently, the clinical impact of this biological entity has been described with worse clinical outcome in patients non responder to clopidogrel, presenting a higher rate of recurrent ischemic events, including stent thrombosis. Meanwhile, a higher rate of bleeding complications have been found in patients with the highest on-treatment platelet inhibition, suggesting a ‘soft’ therapeutic window to avoid both types of recurrent events. Thus, several strategies have been proposed to overcome this poor response to the drug such as higher clopidogrel doses or additional GPIIbIIIa inhibitors in non responders. However, benefit of tailored therapy has been yet established in properly sized, prospective, randomized trial, which are currently ongoing. New comers in the class of P2Y12 inhibitors, prasugrel and ticagrelor, might represent a good alternative for these high-risk patients
Laribi, Med Amine. "CONTRIBUTION À LA SYNTHÈSE DES MÉCANISMES PLANS ET SPATIAUX ET DE ROBOTS PARALLÈLES PAR UNE MÉTHODE ÉVOLUTIONNAIRE." Phd thesis, Université de Poitiers, 2005. http://tel.archives-ouvertes.fr/tel-00706309.
Full textDesaint, Henri. "Identification des bases génétiques de mécanismes de résistance à Ralstonia solanacearum et leur caractérisation chez Arabidopsis thaliana et la tomate dans un contexte de réchauffement climatique." Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30199.
Full textGlobal population is expected to reach nine billion people in 2050. leading to an increased demand for agricultural production from 60 to 110% by 2050. While these global changes have been predicted for several decades, their consequences on global agricultural production have now been reported. Part of this effect is due to altered disease occurrence, driven among others by changes in average surface temperature distribution. Indeed, in addition to more frequent extreme temperature episodes, temperature is one of the climatic parameters of global changes predicted to fluctuate the most, with increases between 2.0 and 4.9°C by 2100. Because of their sessile lifestyle, plants must constantly adapt and respond to diverse environmental conditions, activating specific molecular and physiological changes to minimize damage. However, in the field they are exposed to a variety of concurrent stresses. Reviewing the recent studies specifically investigating the plant-pathogen-heat stress interactions, it overall appears that the mechanism occurring on the plant side are unique and complex, leading to an alteration of a majority of the defense response studied, whatever the pathosystem considered. It is therefore crucial to identify sources of resistance resilient to temperature elevations. The pathosystems chosen for this study are Ralstonia solanacearum/Arabidopsis thaliana and R. solanacearum/Tomato. R. solanacearum is one of the most harmful phytopathogenic bacteria causing tremendous yield losses in crop in tropical, subtropical and warm temperate areas worldwide. Host resistance to R. solanacearum remains the most efficient strategy of disease control. In A. thaliana, the major molecular resistance mechanisms involving the RPS4/RRS1- R pair of immune receptors was recently demonstrated to be inhibited by an elevation in temperature of 3°C. In tomato, two major resistance QTLs have been identified, Bwr-6 and Bwr-12 as well as a tolerant cultivar ‘Hawaii 7996’. Moderately elevated temperature increases susceptibility of the ‘Hawaii 7996’ cultivar to R. solanacearum, and so far, no cultivar performing better under heat stress has been identified. To date, few genes implicated in robust plant defense response under elevated temperature conditions were identified, some of which in the team. Indeed, exploring the natural diversity of response to R. solanacearum at 27°C and 30°C of a worldwide population of wild A. thaliana accessions through Genome-Wide Association (GWA) mapping, two genes were identified and validated, SLL4 and SLL5, involved in QDR to R. solanacearum at 30°C. In an independent GWA experiment, another major QTL corresponding to the CESA3 locus was detected at 30°C. The first objective of my PhD project was therefore to functionally validate other candidate genes in A. thaliana and characterize the role of CESA3 in early plant defense response to R. solanacearum at 30°C. We demonstrated through a reverse genetic approach that CESA3 was involved in QDR to R. solanacearum at 30°C, but also 27°C, acting as a susceptibility gene necessary for the bacterium pathogenicity and infection of A. thaliana. These results hinted at a role of the primary cell- wall in plant immunity, as a passive barrier or as an induced defense and recognition mechanism possibly specifically targeted by the bacteria. The second axis of my PhD was conducted as part of the BURNED project, a public-private research partnership between SYNGENTA and the LIPM. The overall objective of this axis was to develop a GWA mapping approach on a diversity panel mostly composed of wild tomatoes sampled in South America. This panel was phenotyped for its response to R. solanacearum at 28°C and 32°C in controlled conditions, mimicking the predicted elevation of average surface temperature. The GWA mapping analysis was set up and implemented, yielding numerous promising QTLs putatively involved in tomato resistance responses to R. solanacearum at elevated temperature
Augui, Sandrine. "Interactions chromosomiques et inactivation du chromosome X : éléments génétiques et mécanismes impliqués dans la reconnaissance du nombre de chromosomes X et dans la coordination des centres d'inactivation." Paris 11, 2009. http://www.theses.fr/2009PA112373.
Full textIn mammals, dosage compensation is achieved by the inactivation of one of the two X-chromosome during early development in females. X inactivation process is controlled by a complex locus, the X-inactivation centre (Xic), which includes the Xist gene and its antisense transcription unit Tsix/Xite. The Xic senses X chromosome number and initiates inactivation by triggering mono-allelic up-regulation of Xist RNA, and reciprocally, down-regulation of Tsix from one of the two X chromosomes in females. However, the mechanisms underlying sensing and reciprocal Xist/Tsix regulation remain obscure. We recently showed that a previously untested segment of the Xic, lying several hundred kilobases upstream of Xist and enriched in histone H3K27me3 and H3K9me2 marks, brings the two Xic's together prior to the onset of X inactivation (Augui et al, Science 318:1362, 2007). This X-pairing-region (Xpr) can autonomously drive Xic trans-interactions even as an ectopic single copy transgene. Furthermore its presence in male ES cells is selected against, suggesting that it may have a role in triggering Xist up regulation. We proposed that the pairwise interactions driven by this novel X-pairing-region (Xpr) of the Xic might enable a cell to sense that more than one X-chromosome is present in an XX cell, by activating biallelic Xist expression. Furthermore we believe that Xpr pairing then facilitates association between the Tsix/Xite regions, thus rendering biallelic Xist expression monoallelic. Finally, we think that Xpr could be the missing functional region of the Xic since Xpr + Xist/Tsix transgenes seem to recapitulate all Xic function in a male cell line
Dessus-Babus, Sophie. "Chlamydia trachomatis : sensibilité aux antibiotiques et caractérisation moléculaire de souches isolées d'infections génitales récidivantes. Etude des mécanismes génétiques de la résistance aux fluoroquinolones liée à la cible." Bordeaux 2, 1998. http://www.theses.fr/1998BOR28580.
Full textCarpentier, Alban. "Optimisation multi-niveaux de panneaux composites." Toulouse 3, 2008. http://thesesups.ups-tlse.fr/234/.
Full textThe topic of these PhD is to size aeronautical composite panels by optimisation. They are made of stacking of carbon pre-preg plies. The goal is to find the minimal weight for the panel that satisfies strength constraints (damage tolerance, reparability and buckling) but also stacking sequence constraints. To sum-up, the goal is to find all stacking sequences of all different panel areas. This research has allowed to propose a multi-level methodology (4 steps). The first step is the panel thickness law optimisation by using an homogenised material and a gradient-based algorithm. The second step is the research of stacking sequence all over the panel with a fitted genetic algorithm. To perform that, a lay-up table that describes all stacking sequences is used. Then, the third and fourth step allow to adjust thickness law by taking into account the lay-up table issued from step 2. This methodology is applied to an industrial test case (A400M VTP). This application of the methodology allows to underline the performance of the methodology in terms of weight. But, it shows also the modularity of the methodology that is a benefit in industrial context
Marin, Philippe. "Exploration des mécanismes évolutionnaires appliqués à la conception architecturale : mise en oeuvre d'un algorithme génétique guidé par les qualités solaires passives de l'enveloppe." Thesis, Vandoeuvre-les-Nancy, INPL, 2010. http://www.theses.fr/2010INPL022N/document.
Full textThis research tackles the exploration and the qualification of evolutionary mechanisms applied to the architectural design. Here, it is the environmental qualities and more particularly the passive solar qualities of the envelope of the building that will guide the evolutionary process. We become attached more particularly to the initial phases of the conception, and we try to specify a aided digital tool of facilitating and stimulating a creative design. Having established and structured the knowledge on the processes of conception, on the creativity, on the thermal qualities and on the evolutionary methods, we propose a prototypal tool, based on an genetic algorithm and implanted in a modeller software. This one was experimented in the educational environment, and led to us to characterize the modalities of creation and conceptualization of the architectural shape within the framework of an evolutionary instrumentation.So we note the cognitive fall of an implicit thought towards an explicit thought as a main characteristic of the generative tools. Furthermore we insist on the importance of the significant indecision as essential constituent of the creation. Finally we propose the notion of "transform" as characteristic element of a thought of the process and the multiplicity. This "meta-shape" would arise from the description of the conditions of shaping through the parameterisation of the behaviours at the limits and from modalities of emergence
Wong, Jennifer. "Inactivation et activation de régions chromosomiques par des modifications épigénétiques. Mécanismes impliqués et rôle dans la progression tumorale dans les cancers de la vessie." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS484.
Full textIn cancers, gene transcription can be altered by genetic or epigenetic mechanisms. In 2011, my laboratory showed that the progression of bladder cancer could be linked to an epigenetic mechanism called MRES ("Mutiple Regional Epigenetic Silencing"). Tumors with this phenotype exhibit simultaneous inactivation of neighboring genes in 7 regions of the genome. Using a new bioinformatics approach: "SegCorr", we have identified more than 400 genomic regions in which gene expression is correlated. These regions fall into 7 groups and are associated with 6 phenotypes of bladder cancer. In addition, the extinction of gene expression from a small proportion of regions is associated with DNA methylation and / or loss of histone marks associated with active transcription: H3K9ac and H3K4me3 or gains of histone marks associated with transcription repression: H3K27me3 and H3K9me3. Using a new algorithm “Musette”, I have shown that the MRES phenotype is probably not due to genetic alterations. Finally, to understand at which stage of tumor progression of bladder cancer the MRES phenotype might appear, I have shown that bladder cancer tumors induced in mice by ingestion of a carcinogen (N-butyl-N-(4-hydroxybutyl) nitrosamine) could be a good model
Sanka, Michel. "Compréhension des mécanismes moléculaires et des facteurs génétiques impliqués dans le paludisme sévère : analyse des profils transcriptomiques et processus biologiques caractéristiques du neuropaludisme et méta-analyse sur des gènes associés à la résistance au paludisme." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0615/document.
Full textMalaria is one of the most devastating infectious diseases that has affected an estimated 214 million people worldwide and caused nearly 600,000 deaths in 2015. It is caused by infection with the plasmodium parasite, P. falciparum and P. vivax are the most represented. The asexual development of the parasite in the blood causes the pathophysiology of the disease which can evolve from mild malaria to severe malaria, including cerebral malaria. Our work first focused on the analysis of the microarray transcriptome of blood cells of a cohort composed in Senegal. The analysis of the results allow to identify a set of genes whose expression permit to distinguish the transcriptomic profile of cerebral malaria from those of mild malaria and other forms of severe malaria. These genes are enriched in biological pathways involved in the activation of B and T lymphocyte receptors also TLRs and Fcgamma receptors. These genes also include several candidate proteins that have already been tested for resistance to malaria, including RNASE3 and IL1RN
Salah, Bousbia. "Proposition d'une architecture logique d'un système de pilotage hétérarchique évolutif par apprentissage." Phd thesis, Université de Valenciennes et du Hainaut-Cambresis, 2006. http://tel.archives-ouvertes.fr/tel-00355165.
Full textD'une part, dans un contexte fortement concurrentiel, l'agilité devient une caractéristique clef de la prospérité d'un SPBS et symbolise l'actuel objet de compétition entre les SPBS. D'autre part, la mise en place d'un système de pilotage représente un moyen adéquat pour garantir l'agilité d'un SPBS. En effet, la fonction pilotage consiste à décider dynamiquement des commandes pertinentes à donner à un système soumis à des perturbations pour atteindre un objectif donné décrit en termes de maîtrise de performances. La notion de maîtrise intègre non seulement celle de maintien d'un niveau de performance donné, mais également celle de progrès (évolution vers un niveau de performance souhaité ou amélioration continue). C'est sur cet objectif d'amélioration continue des performances des SPBS que nous nous focalisons dans cette thèse.
Cependant, les systèmes de pilotage actuels ne répondent pas efficacement à cette évolution permanente du contexte des SPBS et par conséquent l'objectif d'amélioration continue des performances reste difficilement atteignable. Plus précisément, les systèmes de pilotage sont généralement conçus pour répondre à un besoin spécifique et ce manque de généricité réduit fortement les propriétés d'agilité d'un SPBS. Nos travaux de recherche s'inscrivent dans un cadre qui porte sur le développement d'un système de pilotage pour l'amélioration continue des performances des SPBS. En ce sens, grâce aux Technologies de l'Information et de la Communication (TIC), l'accès aux informations est de plus en plus simple et efficace. Cet accès offre l'opportunité de concevoir des systèmes de pilotage hétérarchiques qui favorisent la décentralisation des capacités décisionnelles.
L'objectif de ce mémoire est de proposer une caractérisation du paradigme d'agilité des systèmes de production de biens et de services, un cadre de modélisation générique des systèmes de production de biens et de services et un système de pilotage hétérarchique évolutif par apprentissage pour l'amélioration continue des performances des SPBS.
Sallé, Damien. "Conception optimale d'instruments robotisés à haute mobilité pour la chirurgie mini-invasive." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2004. http://tel.archives-ouvertes.fr/tel-00762265.
Full textMohamed, Ali Souand. "Le virus Chikungunya : mécanismes évolutifs et outils de génétique inverse." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0665/document.
Full textEmergence of some pathogenic arboviruses is a major public health concern. The Chikungunya virus (CHIKV) is a typical example of re-emerging pathogen since it recently caused large outbreaks in human population, adapted to a new vector and spread to new areas. This emergence is the consequence of phenomena related to the high genomic plasticity of CHIKV. Understanding the mechanisms of adaptation of arboviruses could help to better control these viral pathogens. The first part of this thesis presents a study of the mutations associated with long-term replication of CHIKV in mammalian and mosquito cells. Our results revealed different evolutionary patterns in mammalian and mosquito cells highlighting the difficulties encountered by arboviruses related to host alternation during their natural cycle. The second part of this thesis deals with the homologous recombination, an important process that play a role in the evolution of RNA viruses. Working with the CHIKV, we did not detect any recombination events between attenuated infectious viruses. However, we detected viruses harboring large genomic deletion that could help an attenuated virus by trans-complementation. The last part of this thesis focused on reverse genetic methods that give the possibility to rescue viruses and can be used to study mutations associated with emergence phenomena. Using the CHIKV as a model, we compared the genotype and the phenotype of viruses generated using different reverse genetic methods in cellulo and in vivo using Aedes mosquitos. Our results showed that the choice of the method influenced the genetic diversity of viral populations but whatever the method used, the phenotype was similar
Pasta, Franck. "Etude des mécanismes de l'hyper-recombinaison chez streptococcus pneumoniae." Toulouse 3, 1992. http://www.theses.fr/1992TOU30124.
Full textCormier, Laëtitia. "Mécanismes d’activation transcriptionnelle du régulon Met4 chez Saccharomyces cerevisiae." Paris 11, 2008. http://www.theses.fr/2008PA112288.
Full textMet4 is the transcriptional activator which controls the MET gene network responsible for the biosynthesis of sulfur-containing amino acids. It is actif under conditions of limitation in sulfur and also upon exposure to cadmium (Cd2+) and, therefore, leading to synthesis of the cystein required to formation of glutathione, a thiol tripeptide necessary to complex and detoxify Cd2+. We showed that Met4 recruits at least three coactivators in response to these two conditions: the Mediator, SAGA and TAF. However, some of the subunits of these three complexes seem to be required in only one of the two induction conditions, suggesting a differential activation mechanism by Met4 according to the signal. Within the framework of the global sulfur sparing response in answer to Cd2+, we focused on the molecular mechanisms that govern the switch in expression between Pdc1 and Pdc6, two isoforms of pyruvate decarboxylase with differents contents of sulfur-containing amino acids. We showed that (1) transcriptional activation of PDC6 depends directly on Met4 and its cofactors but involves on atypical DNA binding site, (2) recruitment of the transcriptional machinery at PDC6 promoter and accumulation of PDC6 transcripts are delayed compared to MET genes and (3) PDC6 activation requires high concentrations of Cd2+. In addition, we showed involvement of the corepressor complexe Ssn6/Tup1 in the PDC1 repression, this probably through changes in chromatin structure via the histone deacetylase Rpd3. Finally, this transcriptional switch was also observed under condition of limitation in sulfur
Gomez, Marisa Anahi. "Diversité génétique des Bradyrhizobia nodulant le soja et mécanismes potentiellement impliqués." Dijon, 2001. http://www.theses.fr/2001DIJOS017.
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