Дисертації з теми "Environnemental stress"
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Houdelet, Camille. "Analyse de l'immunoprotéome de l'abeille en réponse à différents stress environnementaux." Thesis, Université Grenoble Alpes, 2020. http://www.theses.fr/2020GRALV009.
Повний текст джерелаThe loss of honeybee colonies could be explained by multiple stress factors (biotic or abiotic) that could act alone or in synergy to perturb the physiology of the domestic bees. The impact of these stressors on the bee health is widely discussed. In the miscrosporidiosis, an infection due to Nosema, the impact of this stressor on the systemic immune response (haemolymph being the mirror of this response) and the epithelial response (gut tissue as target) remains unsatisfactory documented. In the context of an infection by Nosema spp, the spore multiplication that is occurring at the level of the midgut stimulate the gut epithelial immune response. While at the same time, the stimulation of the systemic immune response remains an opened question. The aim of this thesis is to decipher the cross-talk existing between the host (A. mellifera) and the pathogen (Nosema spp.). We investigated the epithelial (gut tissues) and circulating bee immune response (haemolymph) using complementary mass spectrometry approaches (molecular mass fingerprints by MALDI BeeTyping®, untargeted proteomics and MALDI imaging) in a context of a controlled or natural infection by Nosema spores. We have demonstrated new molecular markers of bee health from hemolymph and bees early infected with Nosema from digestive tract. In addition, we have developed the MALDI Biotyping method on our microsporidia model to identify the species at a lower cost. These different elements constitute the development of new diagnostic and even prognostic tools to assist the beekeeper or the health services in their apiary monitoring
Luna, Acosta Andrea. "Les phénoloxydases chez l'huître creuse Crassostrea gigas : biomarqueurs potentiels de stress environnemental." Phd thesis, Université de La Rochelle, 2010. http://tel.archives-ouvertes.fr/tel-00567216.
Повний текст джерелаLuna, Acosta Andrea. "Les phénoloxydases chez l’huître creuse Crassostrea gigas : biomarqueurs potentiels de stress environnemental." Thesis, La Rochelle, 2010. http://www.theses.fr/2010LAROS313/document.
Повний текст джерелаThe Pacific oyster Crassostrea gigas is the leading aquaculture product at the worldwide level. However, massive summer mortalities affect dramatically cultivated and natural oyster populations, especially at young life stages. These events could be linked to an unbalance between the different actors of the triad host – pathogen agent – environment, which could favour a weakening of defence mechanisms in the host, and consequently, the emergence and/or increase of diseases. Among environmental factors that could contribute to this unbalance, chemical contaminants are known to modulate defence capacities in different aquatic organisms. Phenoloxidases (POs) are the key enzymes of a biochemical cascade responsible for the production of melanin and are implicated in immune defences and in self/non-self recognition in invertebrates.Recently, a PO-like activity was detected in C. gigas, and was suggested as a potential biomarker of chemical contamination. However, little is known on the different PO activities present in C. gigas, and on their implication indefence mechanisms in this species. In this general context, the aims of this work were to 1) identify the different types of PO present in different tissues of C. gigas 2) evaluate their potential as biomarkers in experiments of in vivo exposure to organic contaminants, 3) evaluate their potential as biomarkers in in situ biomonitoring studies. We showed, for the first time in this species, the existence of two PO-type activities: a catecholase activity and a laccase activity. Moreover, we observed an in vitro bactericidal effect associated to PO activities against two oyster pathogens, Vibrio splendidus and V.aesturianus, which have often been associated to massive summer mortalities in oysters. Finally, based on a multiple biomarkeranalysis in different tissues of C. gigas, results suggest that POs could be used as biomarkers of environmental stress, rather than of contamination, for biomonitoring studies in coasts and estuaries
Mopin, Clemence. "Stabilité du développement et stress environnemental : analyse morphométrique du fémur de l’homme." Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0068.
Повний текст джерелаAmong the approaches used to characterize the health status in past populations, the use of fluctuating asymmetry (FA) to evaluate developmental stability (DS) in bone is rare. After more than half a century of research, DS remains relatively unknown in humans. Today, geometric morphometrics techniques offer new perspectives. It is now possible to quantify variations more precisely and approach them by analyzing a new morphological element: shape.The aim of this work was twofold:1-Determine whether the geometric morphometrics analysis of FA in humans can distinguish two populations.2-Determine whether this distinction can be attributed to a difference in health status.The data of two populations of known and distinct health statuses and environmental contexts were compared. Two samples of 70 pairs of adult femurs of comparable age and sex were selected. Two sets of 27 landmarks were placed on the 3D isosurfaces of each femur. FA was analyzed and characterized in terms of range of magnitude and pattern of expression in the femur.Finally, this geometric morphometrics analysis allowed to distinguish two populations that have developed under distinct environmental conditions. The population that experienced higher levels of stress expressed a higher degree of FA. After considering the impact of potential factors of variation, the health stress seems to best explain disturbances of DS. However, given its pattern of expression on the femur, the biomechanical factor seems to play also a relative role. Therefore, in humans, the pattern of expression of FA is directed in part by biomechanical constraints but its magnitude remains mostly influenced by health stress
Soualhi, Hamza. "Optimisation de la viscosité des bétons à faible impact environnemental." Thesis, Cergy-Pontoise, 2014. http://www.theses.fr/2014CERG0712.
Повний текст джерелаIt is possible to modify the composition of conventional concrete used in the building field in order to reduce the emission of CO2 associated with their manufacture, particularly in the production of their constituents. This is can be achieved by significantly reducing the amount of clinker and incorporating alternative materials (mineral and chemical additions), which are generally have a lower reactivity and require a low quantity of water, with an adequate level of mechanical performance and durability. This is the case of concrete with low environmental impact. The use superplasticizer in the production of concrete allows increasing their flowability, despite the using of low content of water, but their plastic viscosity remains high and may cause problems of implementation. Controlling the plastic viscosity of this type of concrete is crucial to ensure the development of these products.Within this objective, a rheometer for concrete was developed. The relevant test protocol used for this apparatus enables to characterize the rheological behavior not only for conventional concrete, but also for concrete with low environmental impact.The use of the developed rheometer within an experimental program permits then to highlight the effect of the parameters of concrete compositions, and in particular the used additions (type and rate of substitution) on their rheological behavior.The obtained results from this program propose and validate a mathematical model for assessing the plastic viscosity, which is applicable for ordinary concrete and concrete with low environmental impact. An optimization method for calculating the plastic viscosity of the concrete has been proposed using this model
Mahjoubi, Habib. "Nouvelle stratégie d'amélioration de la productivité végétale en condition de stress environnemental via un meilleur contrôle du cycle cellulaire." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAJ059/document.
Повний текст джерелаSalt stress is one of the main environmental factors limiting plant growth and yield in cereal crops. It is therefore imperative to develop varieties more tolerant to salt stress in order to increase yield and ensure food security. The signaling pathway linking salt stress perception to cellular response was addressed here by studying RSS1-like proteins in plants. RSS1 (Rice Salt Sensitive 1) protein plays an important role in salt stress tolerance. It acts at the interface of stress perception and developmental control and division in meristems. During this work, the RSS1 counterpart named TdRL1 (Triticum durum RSS-Like 1) was isolated from the durum wheat Tunisian variety "Oum Rabiaa". We have demonstrated that TdRL1 carries the conserved D and DEN-Box motifs involved in the post-translational regulation of the protein. In addition, we show that TdRL1 is the functional homologue of RSS1 since it was able to complement the loss-of-function mutant rss1, hypersensitive to salt stress. In addition, heterologous expression of TdRL1 enhances salt stress tolerance in yeast and in Arabidopsis by increasing germination and reducing the accumulation of reactive oxygen species. Our cytological studies have shown that the TdRL1 protein is cytoplasmic in interphase and is localized at the spindle during mitosis. Remarkably, TdRL1 changes its subcellular localization under salt stress treatment and shows a partial accumulation in the nucleus, highlighting the multifunctional nature of this protein during salt stress response. Our data suggest that under salt stress, TdRL1 plays a role in the regulation of the cell cycle in relation with the microtubule network. Pursuing the study of RSS1-like multifunctional proteins will open up new research areas for the creation of wheat varieties that are more resilient to environmental stresses
Vandenbussche, Pierre. "Otolithes et bioindication : conséquence d’un stress environnemental sur la morphologie des sagittae de Dicentrarchus labrax et Oblada melanura." Thesis, Université Côte d'Azur (ComUE), 2017. http://www.theses.fr/2017AZUR4122/document.
Повний текст джерелаThe aim of our study was to validate the most suitable environmental indicator among three approaches: morphological measurements of fish juveniles; quantification of the fluctuating asymmetry of their otoliths; analysis of their otolith shape. In aquaria, results for Dicentrarchus labrax have shown that mono-contamination by classical pollutants, such as phosphorus or zinc, has no effect for concentrations corresponding to those measured in highly anthropized environments. Nevertheless, higher zinc concentrations induce otolith shape alterations in addition to their negative impact on fish size and weight. On the basis of our three-year in situ Oblada melanura samplings, we have demonstrated that, in a replicable manner, compared to preserved areas and small waterway mouths, mid-size recreational harbours negatively impact juvenile standard length and also alter otolith shape. By comparison with in aquaria results, these alterations are consistent with a synergy of disturbance sources which taken independently do not have any impact. Taking into account all our results, we deduce that size and weight are easy to measure but show response variability. Measurement of fish juvenile otoliths' fluctuating asymmetry does not seem to be suitable for use in bioindication. Conversely, fish juvenile sagittae shape analysis is well-suited to surveys of environmental modifications, for fishes from two different families, Moronidae and Sparidae. This analysis seems to be a promising tool for bioindication, with a practical application for environmental managers
Mella-Flores, Daniella. "Diversité génétique et fonctionnelle des cyanobactéries picoplanctoniques marines et adaptation aux stress environnementaux." Paris 6, 2011. http://www.theses.fr/2011PA066359.
Повний текст джерелаLariviere, Delphine. "Méthodes bioinformatiques d'analyse de l'histoire évolutive des familles de gènes ˸ intégration de données, indices évolutifs, et analyses fonctionnelles appliquées aux familles de gènes impliquées dans la réponse des plantes aux stress environnementaux." Electronic Thesis or Diss., Montpellier, SupAgro, 2016. http://www.theses.fr/2016NSAM0041.
Повний текст джерелаThe study of gene families and their evolutive history brings precious evidences for the functional annotation of families. The functional transfer depends on one hand on the relationship between genes, and on another hand on the sequence divergence. In order to facilitate the comprehension of gene families, the inference of their evolutive history must be correlated to functional evidences and annotations. This inference is possible through the integration of several heterogeneous data. Evolutive evidences can come from several different data sources and need several tools . It is therefore important to clearly identify both these sources and tools, but also to implement their integration in a common analysis specific to the studied organisms. After studying plant genomes specificities, and their specific mode of evolution, we responded to this problematic through the development of an integrative system containing expertingly chosen data, and implemented tools dedicated to the analysis of gene families. The system also propose a synthetic visualisation analytic tool and an original method to integrate syntenic data for gene family analysis. This system has then been used to study gene family of interest, implied in abiotic stress resistance in plants, that allows us to discuss the intake of the system for gene family analysis
Quéméner, Audrey. "Étude des populations de cellules souches adultes dans le tissu adipeux et le muscle chez le porc en croissance en réponse à un facteur environnemental." Electronic Thesis or Diss., Rennes, Agrocampus Ouest, 2021. http://www.theses.fr/2021NSARI083.
Повний текст джерелаThe work carried out during this PhD thesis made it possible to demonstrate that moderate inflammation, induced by a six-week exposure to sanitary stress in growing pigs, has a different impact on the molecular and cellular features of adipose and muscle tissues. Thus, despite the lack of detection of an inflammatory state in adipose tissue, we demonstrated that perirenal adipose tissue (PRAT) was more sensitive to sanitary stress than subcutaneous adipose tissue (SCAT). Indeed, the decrease in the relative weight of PRAT was associate with a decrease in the expression of genes involved in fatty acid synthesis in pigs housed in poor hygiene conditions compared with pigs housed in good hygiene conditions. With respect to skeletal muscle tissue, the increase in hematopoietic cells in response to sanitary stress suggests the presence of an inflammatory state in this tissue. With the phenotyping strategy we have chosen, we have shown that the longissimus dorsi muscle, compared to SCAT, exhibited a greater diversity of populations of adult mesenchymal stem cells. Among them, the quantity of putative PICs (CD45-CD56+CD34+CD140a+) was increased following an exposure to sanitary stress. The proliferation of this cell population could contribute to muscle regeneration, induced by the inflammatory state due to sanitary stress. In the end, the modulation of adult stem cells opens up new perspectives for modifying the composition of lean and fat tissues in growing animals
Loiseau, Claire. "Réponses au stress environnemental et à la pression parasitaire en populations naturelles : approches physiologique et génétique : Etudes chez le moineau domestique Passer domesticus." Paris 6, 2007. http://www.theses.fr/2007PA066468.
Повний текст джерелаMersch, Marjorie. "Analyse de la méthylation de l'ADN par séquençage haut-débit chez la Poule." Thesis, Toulouse, INPT, 2018. http://www.theses.fr/2018INPT0107/document.
Повний текст джерелаAnticipating the impact of environmental changes (on climate and feed) is a crucial issue for livestock production systems, including poultry. The influence of the environment on phenotypes is partly mediated by epigenetic phenomena, including DNA methylation, which may be involved in the regulation of gene expression. These mechanisms do not affect the DNA sequence but can be inherited by mitosis or meiosis. The interactions between epigenomes and gene expression are increasingly being studied in animal models and in plants. However, the mechanisms of regulation of genome expression through DNA methylation are relatively unknown in birds. This thesis work is based on two experimental devices realized in chicken aiming to characterize the methylome by high-throughput sequencing. The methylation patterns across the genome, and their link with expression, were first established by whole-genome bisulfite sequencing (WGBS) in whole embryos, following a reduced representation bisulfite sequencing (RRBS) from hypothalamus of adults. To date, no specific chicken RRBS study has been published. These two analyses were carried out by developing an optimized bioinformatics pipeline, available for scientific community. Overall, the pattern of methylation in chicken is like those in mammals: CpG islands - dinucleotides CG-rich regions which are often poorly methylated, and which are found mainly in the promoter regions of the genome - are generally poorly methylated in promoters on WGBS and RRBS data. Embryo methylome analyses confirmed the absence of a dose-compensation phenomenon on sex chromosomes, or the presence of a hypermethylated region on the Z chromosome. The analyses of RRBS data revealed an overall hypermethylation of CGs across the genome, suggesting a methylation response to environmental stress. From the analysis of WGBS data, we found that the level of methylation in promoters was negatively correlated with the expression of the associated gene. For the first time, a specific allele methylation was also detected between chicken lines whose frequency is comparable to that observed in humans. On the RRBS data, preliminary results of the methylome response to environmental stresses showed the complex nature of this relationship. The use of a low-energy diet would led to greater mobilization of body fat, while individuals with heat stress had a lighter body weight. Integrating these data with phenotypic measurements would allow to link methylation and environment. Beyond the fundamental aspect of this thesis, the method developed in this work could be applied to livestock systems to breed animals better adapted to a changing environment, by improving production traits
Zalc, Antoine. "Study of Pax3 and Pax7 functions during the development of the mouse embryo." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066220.
Повний текст джерелаThis thesis aims to decipher how Pax3 and Pax7 transcription factors control cell cycle progression of progenitor cells in different tissues.Cell cycle regulation of Pax3+ myogenic progenitors during limb muscle developmentWe showed that cell cycle exit, mediated by the cyclin-dependent kinases inhibitors (CDKI), and muscle differentiation, controlled by the myogenic regulatory factors (MRF), can be genetically uncoupled during development. We dissected a functional interplay between Notch signalling and both MRF and CDKI activities, for maintaining the cycling status of the progenitor cells. Further, we identified a CDKI, muscle-specific DNA regulatory element, activated by the MRF in myoblasts but repressed by Notch signalling in progenitor cells, controlling the equilibrium between amplification of the progenitor pool and the establishment of functional muscle.Control of Pax3+ neural crest derivatives growth, and maintenance during craniofacial developmentAlthough studies showed Pax3 and Pax7 to be essential during early neural crest development, their role during craniofacial formation is unknown. Using Pax3/7 mutant mice displaying facial clefts, we uncovered that these defects are associated with an up-regulation of the Aryl hydrocarbon Receptor (AhR, the receptor to dioxin) signalling pathway. In Pax3/7 mutants, increased AhR activity drives facial mesenchymal cells out of the cell cycle, while inhibiting AhR rescues the cycling status of these cells and the facial closure of Pax3/7 mutants. Our results identify a molecular link between an environmental stress response pathway and a Pax3/7 downstream gene regulatory network during normal craniofacial development
Dutilleul, Morgan. "Réponses microévolutives et coûts adaptatifs de populations de Caenorhabditis elegans exposées à des stress environnementaux." Thèse, Montpellier 1, 2013. http://www.archipel.uqam.ca/5860/1/D2565.pdf.
Повний текст джерелаFiers, Marie. "Origine des altérations superficielles du tubercule de pomme de terre : de la microbiologie du sol à l'environnement pédo-climatique." Phd thesis, Université de Bourgogne, 2010. http://tel.archives-ouvertes.fr/tel-00572491.
Повний текст джерелаDeloux, Estelle. "POLITIQUES DE MAINTENANCE CONDITIONNELLE POUR UN SYSTEME A DEGRADATION CONTINUE SOUMIS A UN ENVIRONNEMENT STRESSANT." Phd thesis, Université de Nantes, 2008. http://tel.archives-ouvertes.fr/tel-00348191.
Повний текст джерелаJamal, Dima. "Influence de stress environnementaux sur les propriétés physicochimiques de jeunes biofilms en cours de formation : étude par spectroscopies vibrationnelles infrarouge-Raman et de force AFM." Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0075/document.
Повний текст джерелаBiofilms are complex communities of microorganisms, embedded in an auto-produced matrix of extracellular polymeric substances or EPS. Biofilms form on the surface of most materials, whether or not they are of biological nature, and cause major economic problems as well as public health concerns. Bacteria within a biofilm also called sessile bacteria, have phenotypic characteristics that distinguish them from their planktonic counterparts, rendering them more resistant to antibiotics and to disinfection strategies. Hence, the prevention of their formation and/ or their elimination requires the use of strategies that are well suited to the sessile mode of life. The development of these strategies begins with a better understanding of the physicochemical contributions that govern the interaction between the sessile community and its environment especially during the first steps of biofilm formation. Two main objectives were defined at the beginning of this thesis, the first was to characterize, in situ, and in real time the development of nascent biofilms. Two bacterial models were studied: a natural and ubiquitous strain of Pseudomonas fluorescens and a model strain of Escherichia coli genetically modified to overexpress one type of EPS. The second objectif was to study their responses towards an environmental or chemical stress; particularly how their development would be affected under extreme conditions of pH. To gain these objectives, different techniques were combined to study from the molecular to the cellular scale the development of biofilms. Fourier Transform Infrared spectroscopy in attenuated total reflection mode was used to evaluate in real time the development of biofilms. We were able to detect changes in the IR-ATR spectral profile along biofilm formation under favorable and non favorable growth conditions. 24 h - old biofilms were characterized using confocal Raman microspectroscopy, which allowed us to gather localized information on their chemical composition. The structure of biofilms was visualized using epifluorescence microscocopy. Finally, physico-chemical properties of EPS were quantified using single molecule force spectroscopy
Sechet, Julien. "Analyse fonctionnelle de gènes impliqués dans la signalisation de l'ABA et la réponse au stress dans les graines d'Arabidopsis thaliana." Electronic Thesis or Diss., Paris, AgroParisTech, 2014. http://www.theses.fr/2014AGPT0004.
Повний текст джерелаAbscisic acid plays an essential role in limiting water loss from plants through the control of stomata aperture and the induction of a range of responses to water-‐‐deficit. During seed development ABA induces dormancy and desiccation tolerance as well as controlling germination, in particular in response to environmental constraints. Two approaches have been used to identify new factors involved in the hormonal control of germination and responses to environmental stimuli. The first consists of the identification of two genes defective in mutants affected in the hormonal control of germination, as well as water-deficit resistance in one mutant. Whole‐genome resequencing was used to identify the mutated genes. The first mutant, named xyl1-4, was isolated by its resistance to an inhibitor of gibberellin synthesis, and demonstrated the implication of xyloglucans (XyG) in germination control. In effect, the XYL1 locus encodes an α-xylosidase required for the maturation of XyG in the cell wall, through the trimming of xylose ramifications. Our results indicate that XYL1 plays a major role in the cell wall remodelling processes that control both embryo growth potential and the resistance of the endosperm during germination. The second mutant, has2, was selected in a screen for suppressor mutants of the excessive evapotranspiration on water deficit observed in the ABA biosynthesis mutant aba3-‐‐1 (Plessis et al., 2011). This mutant exhibits a range of germination phenotypes related to its sensitivity to environmental constraints, indicative of defects in hormone signalling. The HAS2 locus encodes a mitochondrial protein with PPR (pentatrico-peptide repeat) motifs that has previously been termed LOI1/MEF11. has2 mutant analysis showed the importance of mitochondrial respiration in plant tolerance to diverse stress and in germination processes. Finally we used a reverse genetic approach for the analysis of three mitochondrial sHSPs (small heat shock protein) in the response to abiotic stress; the germination phenotypes of single and multiple mutants for the HSP23.5, HSP23.6 and HSP26.5 genes were examined. This study has demonstrated the key role of HSP23.6 in the response to salt stress and the role of all three sHSPs in the control of evapotranspiration during water deficit
Manduzio, Hélène. "Étude des modifications d'expression protéique sous l'effet d'un stress environnemental chez deux bivalves estuariens, la moule zébrée (Dreissena polymorpha) et la moule bleue (Mytilus edulis) : suivi de marqueurs de défense cellulaire et approche protéomique." Le Havre, 2004. http://www.theses.fr/2004LEHA0006.
Повний текст джерелаThis research was initiated in order to study the modifications of protein expression induced in sentinel organisms exposed to various conditions of environmental stress. The main goal was to identify molecular actors involved in the response of bivalves to contaminants and to better understand the cellular and molecular mechanisms activated being either alterations related to the toxicity of xenobiotics or adaptive answer of the organisms. Two bivalve models were chosen, the zebra mussel Dreissena polymorpha, a freshwater species, and the blue mussel Mytilus edulis, a marine water species. The first approach was targeted on the study of oxidative stress by measuring the activity levels of the antioxidant enzymes glutathione reductase, glutathione peroxidase and superoxide dismutase, and of the detoxification enzyme, glutathione S-transferase. The second approach was open-framed and consisted in a proteomic study carried out on blue mussels submitted to various environmental conditions
Moser, Gabriel. "Stress environnementaux et comportements urbains." Paris 5, 1990. http://www.theses.fr/1990PA05H056.
Повний текст джерелаUrban life is stressful. The literature on urban stress and how it influences social behavior is heterogenious and often inaccurate, and the existing models, essentially based on laboratory research, are insufficient to explain the behavior of urbanites in a complex environment characterized by the simultaneity of a multitude of acute and chronic stresses. Considering stress as an interac1tional process and analyzing its effects in terms of mechanisms, leads to propose a model of the effects of stress in urban environments. The urbanite is exposed as well to specific urban conditions which are stressful by themselves, as to occasionally emerging stimulations (noise, density, etc. ) which add themselves to the general urban conditions, and he perceives, evaluates and reacts to the acute stimulus with respect to his usual exposition. His behavioral reactions are either automatic either mediated by cognitive processes. The intervention of one or another of these mechanisms depends on the intensity of the environmental stimulations and on the resulting activation. Only a mean level of activation, and evaluated as such by the subject, leads to cognitive control behavior in order to cope efficiently with the situation
Ducret, Stéphane. "Contribution de la physiologie et de la mécanique dans l'étude des sports de glisse : rôle de l'usure des matériaux et de la fatigue de l'athlète dans la performance." Lyon 1, 2003. http://www.theses.fr/2003LYO10192.
Повний текст джерелаWild, Michael. "Functional characterization of the DELLA RGA-LIKE 3 in Arabidopsis thaliana." Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAJ051.
Повний текст джерелаThe phytohormones gibberellins (GA) regulate major aspects of plant growth in response to endogenous and environmental signals. Upon the perception of stress, the levels of bioactive GA are adjusted, hence allowing a flexible growth response to environmental variability. At a molecular level, GA promote growth by stimulating the degradation of the growth repressing DELLA proteins. DELLAs are versatile nuclear proteins with several remarkable features, such as transactivation activity and protein–protein interaction capacities. Thus DELLAs interact with a series of highly divergent proteins, including different transcription factor families, but also the Jasmonate (JA) ZIM-domain (JAZ) proteins, repressors of JA signaling. The aim of this thesis work consisted in the characterization of the biological function of the DELLA RGA-LIKE3. I could show that RGL3 modulates plant defense responses against biotic stresses
Clergué, Boris. "Évaluation de l'impact des pratiques agricoles sur les fonctions de la biodiversité à l'aide d'indicateurs agri-environnementaux : approche globale et développement d'un indicateur de "résistance aux stress biotiques"." Thesis, Vandoeuvre-les-Nancy, INPL, 2008. http://www.theses.fr/2008INPL048N/document.
Повний текст джерелаRelevant tools for assessment are necessary to evaluate the impact of agricultural pratices on the functions provided by biodiversity at the plot scale to the landscape scale. The goal and the innovation of this work has been to explore a new method of creation of an assessment tool of the biodiversity functions. We have chosen like assessment method the agri-environmental indicators, which make it possible to evaluate the impact of agricultural practices on environment compartments (water, soil, air, fauna and flora) and help to decision-making. We thus propose a general architecture of an indicator of functional biodiversity and the detail of an agronomic function indicator of importance: resistance to the biotic stresses. Within this indicator, an under-indicator is: the « role of the terrestrial auxiliaries ». Carabids will be used as model auxiliary for the construction of this under-indicator. Two building methods of indicators are compared: a method with expert saying and a method with data mining, this second method representing an innovation of the thesis. The results of these methods are then compared with field datas leads on the Vittel territory. Field datas related to the follow-up of the carabid populations and the organization of the agricultural landscape. A treatment by a geographical information system allowed the validation of the indicators obtained
Torterotot-Immel, Françoise. "Apports de la biochimie et de la protéomique dans l'étude de modifications du métabolisme cellulaire à travers deux exemples : l'amyloïdogénèse de différentes protéïnes de champignons ascomycètes et la caractérisation du protéome d'une plante invasive résistante à un stress environnemental." Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0297.
Повний текст джерелаA number of neurodegenerative illnesses such as Creutzfeld-Jacob disease in humans or the disease known as mad cow disease in bovine, are due to misfolding of a cellular protein called prion. These proteins are not pathogenic for human and can form amyloid fibers like mammalian prion. They are therefore a useful tool to study molecular events responsible for the emergence and propagation of prions. In S. cerevisiae, the Ure2p protein is associated with [URE3] prion phenotype and is aggregated in this cell. Initially, I developed the conditions to characterize Ure2p amyloid fibers by proteolysis and we showed that [URE3] aggregates obtained in vivo were different than amyloid fibers produced in vitro. In a second phase, the technicity acquired during the biochemical study of Ure2p allowed me to approach the study of an ortholog, Saccharomyces paradoxus Ure2p (Ure2p-Sp), which is not an "in vivo" prion. After showing that soluble forms of the two proteins have the same biochemical characteristics, I show that they have the same propensity to form amyloid fibers. In this study we show that these fibers are infectious in vivo, suggesting that the incapacity of Ure2p-Sp protein to switch into a prion form is rather due to a failure in prion propagation mechanism rather than differences in amyloid structure itself.Then using all technologies that I introduced in the laboratory, I studied the relationship between amyloid structure and toxicity in S. cerevisiae. We showed that it was possible to transform a non-toxic amyloid protein in a toxic form by changing only a few numbers of amino acids. An in vitro study has also shown that the toxic protein was organized into short amyloid fibers that could mimic the intermediates responsible for toxicity in neurodegenerative diseases.The last chapter of this manuscript focuses on research that I developed in the Laboratory of Ecotoxicology Interactions,Biodiversity, Ecosystems, Metz. Within this laboratory, we aim at identifying effects of disturbances and physico-chemical analysis of the mechanisms involved at different scales of observation, from organisms to ecosystems.Progress in genomes sequencing allows an exceptional development in post-genomic biochemistry and can highlight new proteins through functional studies. In order to better understand molecular events responsible for these responses, I introduce a differential technique of proteomics: a DiGE two-dimensional electrophoresis (Differential In-Gel Electrophoresis). I developed this technics in a proteome study of an invasive plant, the goldenrod Solidago canadensis, under metal stress. This proteomic study supplements a phyto-sociological study of plants competent in colonizing a very poor soil but also of biodiversity data, growth and measures of the antioxidant response of these plants. This analysis revealed that in polluted soils, the goldenrod achieves not only to produce energy for its growth but it also achieves to biosynthesize intermediates of glutathion and phytochelatins. Thus, the goldenrod is able to adapt to its environment, which allows it to be tolerant to pollution. My first results of post-genomic biochemistry provide new bases for understanding the molecular mechanisms behind environmental tolerances. These studies may help us to identify the most adapted plants to these environments and why they are. They may help us to understand the effects of these pollutants and allow the development of innovative technologies for phytoremediation to restore polluted soils
Pigneret, Mathilde. "Réponses écophysiologiques à une pollution d’origine anthropique chez un organisme sentinelle et conséquences sur le fonctionnement des bassins d’infiltration." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1031/document.
Повний текст джерелаHuman populations are exposed to numerous pollutants. It is now necessary to evaluate the toxicity of urban contaminants in receptor ecosystems. In anthropized areas, many pollutants (mainly hydrocarbons and heavy metals) accumulate on the impervious surfaces (roads, parks, buildings, rooftops…). During a rainfall event, these compounds are re-suspended and drained up to stormwater infiltration basins. These structures were built to detoxify and to infiltrate runoff water to underlying groundwater. Toxic compounds are captured and accumulated in the fine sediment layer of the infiltration basins, where their concentrations may achieve important concentrations. Despite this harsh constraint, a few invertebrates inhabit stormwater basin sediments and have developed specific metabolic, physiological and/or behavioural adaptations. One of the most spread is the oligochaeta Limnodrilus hoffmeisteri. This tubificid worm burrows galleries (bioturbation activity) in sediments where it enhances the organic matter mineralization and the nutrients recycling. This species has an essential role in the infiltration basin functioning and on groundwater quality. L. hoffmeisteri is considered both as a sentinel species of ecosystem health and an engineer species. The first aim of this work was to highlight the ecophysiological responses that allow L. hoffmeisteri to survive in these harsh conditions. We exposed this organism during 1, 3 or 6 months to polluted sediments (from 3 infiltration basins), under laboratory conditions. Then, we measured the survival, the oxygen consumption, the energy body stores, the oxidative stress induced by urban pollutants (through the lipid peroxidation level), and the antioxidant defence mechanisms (the activity of the antioxidant enzymes) in L. hoffmeisteri. The same analyses were realized on worms incubated 1 to 6 months in a sediment from a non-urbanized environment (considered as a low-polluted/control sediment). The second objective of the present work was to determine the impact of urban pollutants on aerobic and anaerobic metabolisms in L. hoffmeisteri. We measured several mitochondrial parameters (the mitochondrial respiratory chain activity and the ATP production rate) and anaerobic end product concentrations in worms exposed to the 4 same sediments (polluted or not). This study demonstrated that urban pollutants induced a shift from aerobic to the anaerobic metabolism, linked to a mitochondrial dysfunctioning. Moreover, this study also showed that two anaerobic end products (succinate and propionate) constitute relevant biomarkers of urban pollution. Lastly, the third goal of this thesis was to evaluate the impact of an anthropic pollution on the engineering activity of L. hoffmeisteri (i.e. its role in the infiltration basin functioning). To this end, we measured during 1 month the burrowing activity of this tubificid worm using X-ray tomography, in microcosms containing slightly or highly polluted sediments. We measured nutrients fluxes, dissolved oxygen, CO2 and CH4 concentrations during the experiment to determine the influence of the pollution rate on nutrients recycling. These measurements were also realized in microcosms with or without worms, to quantify the functional role of engineer organisms
Vanhoenacker, Eloïse. "The evolution of sex : theoretical study based on quantitative genetics models ad experimental approach using the facultatively sexual rotifer Brachionus plicatilis." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS347.
Повний текст джерелаThis thesis aimed at investigating some of the possible evolutionary benefits of sexual reproduction using both a theoretical and an experimental approach. The first approach consisted in developing evolutionary quantitative genetic models for the evolution of sex. A first model (based on Fisher’s geometrical model) considers an arbitrary number of phenotypic traits under stabilizing selection around a fixed optimum, and explores the effect of mutational bias acting on the traits. A second model represents a phenotypic trait under both stabilizing and directional selection (modeled by a linear, cyclical or stochastic change in the phenotypic optimum). Individual-based simulations showed that in the absence of mutational bias or environmental change, the population evolves towards asexuality. However, with mutational bias, intermediate rates of sex are maintained in the population even when the cost of sex is strong. Higher rates of sex evolve when the phenotypic optimum changes over time. The second part of the thesis consisted in developing an experimental model to test theoretical predictions on the possible benefits of sex, using the facultatively sexual rotifer Brachionus plicatilis. The results demonstrate genetic variation for investment in sex between strains from the same natural population, and the existence of transgenerational maternal effects affecting the rate of sex. Finally, the results from an evolution experiment suggest that sex facilitates adaptation to a stressful environment
Alfonso, Sébastien. "Interactions entre traits de personnalité des téléostéens, environnement et polluants." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTG083/document.
Повний текст джерелаIn the frame of this thesis, we first studied the establishment of personality in teleost, the consistency across context and different life stages as well as the associated physiological mechanisms. Personality appeared consistent across contexts over a short time period but it was no longer the case over a long period of time, especially between different life stages. Physiological mechanisms of stress regulation, as well as activity and neural plasticity, differed according to individual boldness. Then, we studied the physiological and behavioural responses of teleost fish chronically exposed to an environmentally relevant mixture of POP (PCBs and PBDEs), as well as those of their unexposed offspring. Different behavioural alterations in larval photomotor response, boldness and a behavioural syndrome linked to anxiety have been observed between generations up to the F2 or F4 generations. Alterations in the expression of enzymes responsible of DNA methylation were also observed suggesting that epigenetic mechanisms are involved in the transmission of these behavioural alterations in unexposed offspring. Behaviour was also studied under stressful water quality conditions in order to set behavioural welfare indicators. Results showed that individuals cope with these alterations in oxygen levels or NH3 concentration by decreasing their swimming activity and group cohesion. In addition, we observed that the normal thigmotaxis behaviour was inhibited during exposure to degraded water quality. It suggests a hierarchy of behavioural adaptations depending on stress severity. Finally, we studied the behavioural responses to a decrease in oxygen level according to personality: bold individuals decreased their activity and swimming cohesion with greater amplitude than shy individuals which decreased with higher amplitude thigmotaxis behaviour. These abilities to cope with stress, depending on the personality of teleost fish, bring new perspectives to face both ecological and aquaculture issues
Plantivaux, Amandine. "Implication du stress oxydant en réponse à des perturbations environnementales." Nice, 2006. http://www.theses.fr/2006NICE4035.
Повний текст джерелаOxidative stress occurs when the physiological balance between pro-oxidants and antioxidants is disrupted and the oxidants favored, with possible cellular damages. This imbalance can be caused by environmental modifications. The marine invertebrate Anemonia viridis (sea anemone) is an appropriate model to study the oxidative stress. This animal harbors photosynthetic symbionts in its cells. By their photosynthetic activity, the symbionts create daily hyperoxia in the host tissues. In order to understand how the animal can deal with such an hyperoxia, their superoxide dismutases (SOD), key enzymes of detoxication, were characterized. The symbiotic association between the sea anemone and the zooxanthellae also faces environmental modifications. Many stresses (temperature, UV) can disrupt the symbiosis, leading to the bleaching of the animal host. The damages caused by a rise in temperature were studied, especially the protein carbonylation. Exposure to UV rays is another example of environmental alteration, which increases the production of oxidative molecules. Skin being the first protection of the organism against UV, it is submitted to oxidative stress. In collaboration with the cosmetic firm Vincience, assays to measure the antioxidant activity of a molecule were developed on cultured human skin cells
Fourçans, Aude. "Dynamique des communautés bactériennes de tapis microbiens soumis aux stress environnementaux." Pau, 2004. http://www.theses.fr/2004PAUU3007.
Повний текст джерелаThis thesis relates to the study of the bacterial communities dynamics of microbial mats in order to understand their adaptive mechanisms face to environmental stresses. The bacterial biodiversity was analyzed by T-RFLP, molecular approach of microbial ecology. This work concerned, firstly, the description of two photosynthetic microbial mats of distinct salinity, marine (Orkneys Islands), and hypersaline (Camargue Salterns). The spatio-temporal distribution of communities in Camargue mat during a nycthemeral cycle was then studied. Adaptive behaviors in phototrophic and sulfate-reducing bacteria could be revealed, of which migration. Thirdly, the analysis of the hydrocarbon impact on the Guérande and Camargue mats finally showed a real influence, with the successive development of communities having capacities of adaptation to hydrocarbons
Nguyen, Thi Thuy An. "Étude des réponses des insectes aux stress environnementaux par une approche protéomique." Thesis, Université Laval, 2008. http://www.theses.ulaval.ca/2008/25379/25379.pdf.
Повний текст джерелаTagourti, Jihen. "Caractérisation d'une kinase et d'un chaperon de stress environnementaux chez Escherichia coli." Paris 7, 2009. http://www.theses.fr/2009PA077113.
Повний текст джерелаIn this memory, we are investigated to study the acid stress chaperone HdeB and a stress kinase YeaG from Escherichia coli. HdeB, acid stress chaperone: Many neurodegenerative diseases are caused by protein aggregation and the incapacity of the cells to degrade these aggregates. We have characterized the HdeB protein as a periplasmic acid stress chaperone, which belongs to the hdeAB operon. A periplasmic chaperone, HdeA, which plays a role in acid stress résistance, was discovered (Gajiwala & Burley, 2000; Hong et a/. , 2005). HdeA and HdeB are required for protein solubilization at acîd pH. Thus, Escherichia coli possess two acid stress chaperones that prevent periplasmic protein aggregation. We show that, both HdeA and HdeB are required for protein solubilization at acid pH. HdeA is more efficient than HdeB at pH 2 and HdeB is rnore efficient than HdeA at pH 3. YeaG, stress kinase: Protein phosphorylation is an important mechanism to translate extracellular signals into cellular responses and is carried out by coupled protein kinases and phosphates. In this context, we have focused on the study of YeaG. E. Coli YeaG is more than 20-fold overexpressed during both stationary phase, acid and salt stress suggesting that it plays important role in cellular protection against environmental stresses. We cloned, expressed, purified and characterized YeaG as an autokinase, endowed with protein kinase activity towards casein, a substrate of serine protein kinases. Also, we detect an YeaG-dependent substrate from E. Coli extract (MW= 65 kDa; pHi= 6,8)whose phosphorylation increase
Vidal-Dupiol, Jérémie. "Stress environnementaux chez le corail scléractiniaire Pocillopora damicornis : du modèle expérimental à l'identification de marqueurs fonctionnels du stress." Phd thesis, Ecole pratique des hautes études - EPHE PARIS, 2011. http://tel.archives-ouvertes.fr/tel-00608572.
Повний текст джерелаFerrat, Lila. "Bioindicateurs des variations environnementales chez les végétaux." Habilitation à diriger des recherches, Université Pascal Paoli, 2010. http://tel.archives-ouvertes.fr/tel-00593175.
Повний текст джерелаVila, Gilbert. "Etats de stress post traumatiques chez l'enfant et l'adolescent : Réalité et Environnement." Paris 7, 2002. http://www.theses.fr/2002PA070014.
Повний текст джерелаOur first Hypothesis was that psychopathological effects of stress and trauma are different, on the qualitative level and not on the quantitative level. We have drawn a parallel between personal studies on various populations suffering from stress or trauma : children exposed to trauma or stress, particularly pediatric diseases. Our methods were based on standardized data recording and statistical analyses (path analysis and multivariate methods). We have shown that Post-Traumatic Stress Disorder (PTSD) is characteristic of Trauma and is not observed when it is a matter of stress. PTSD does exist in children, in our culture and in the way the international classifications have described it. Before 5 years of age, it is necessary to correct the diagnostic criteria. Trauma exposure is indeed the major etiologic factor and the etiopathogeny may not amount to the parent reaction and the disorders they induce or reinforce in their children, even if parents can act a modulating or reinforcing role and be themselves victim of the agression or victimized in a second time. .
Lebègue, Nathalie. "Radicaux libres dérivés de l'oxygène et antioxydants : méthodes de détection, approche biologique et environnementale." Paris 5, 1999. http://www.theses.fr/1999PA05P109.
Повний текст джерелаFerrat, Lila. "Réactions de la Magnoliophyta Marine Posidonia Oceanica en réponse à des stress environnementaux." Corte, 2001. http://www.theses.fr/2001CORT3063.
Повний текст джерелаMary, Isabelle. "Mécanismes moléculaires de la réponse aux stress environnementaux chez la cyanobactérie marine prochlorococcus." Rennes 1, 2003. http://hal.upmc.fr/tel-01117616.
Повний текст джерелаBouffier, Bruno. "Genetic and ecophysiological dissection of tolerance to drought and heat stress in bread wheat : from environmental characterization to QTL detection." Thesis, Clermont-Ferrand 2, 2014. http://www.theses.fr/2014CLF22532/document.
Повний текст джерелаA stagnation of wheat yield was reported in France and other countries worldwide since the 1990’s, which incriminated mainly drought and heat stress. Improving the European wheat tolerance to them is of first importance. This study aimed to investigate the genetic determinism of the tolerance to such stresses. Three CIMMYT bread wheat populations combining complementary heat and drought adaptive habits were grown in Northern Mexico under irrigated, drought and heat-irrigated treatments from 2011 to 2013. The trial network comprised 15 trials and both physiological and agronomic traits were scored. First, an environmental characterization methodology was developed and resulted in the identification of six main environmental scenarios in the network. A representative environmental covariate was extracted from each of them. Then, a factorial regression model leaded to the dissection of the genotype-by-environment interaction and highlighted differential stress sensitivity of the germplasm. Finally, a multi-environmental QTL detection resulted in the discovery of genomic regions involved in the control of both physiological and agronomic traits and the study of their sensitivity to the environment. From the environmental characterization to the QTL detection, this study resulted in the development of a tool for breeders which may enable the evaluation of the potential of any genotypes in front of a range of environment, but also the identification of genomic regions involved in the control of the tolerance to drought and heat stress in bread wheat. This may help in improving the tolerance of the European bread wheat germplasm to drought and heat stress
Nguyen, Dang Dan. "Revêtements polymères sous contraintes environnementales couplées." Phd thesis, Université de La Rochelle, 2012. http://tel.archives-ouvertes.fr/tel-01065519.
Повний текст джерелаZahalca, Cristina-Anca. "Fiabilité de systèmes en environnement aléatoire stressant." Grenoble INPG, 1999. http://www.theses.fr/1999INPG0140.
Повний текст джерелаMohamadi, Fahoullia. "La métabolomique appliquée à l'étude de l'impact de stress environnementaux sur les coraux scléractiniaires." Perpignan, 2014. http://www.theses.fr/2014PERP1241.
Повний текст джерелаDuring the past three decades, nearly 30 % of the word’s coral reefs have been severely affected by bleaching and has resulted in significant losses of live coral in many parts of the world. Coral bleaching is the consequence of the loss of corals’algal symbiont (zooxanthellae), or the deficiency/degradation of symbiont’s photosynthetic pigments. Understanding the mechanisms of bleaching is a real challenge as corals bleach under a broad range of external stimuli that may occur sequentially or simultaneously. Despite the numerousscientific progresses achieved recently, the mechanisms of coral bleaching are not fully understood. In this project, an untargeted approach based on metabolomic study was developed to highlight coral’s health status. Metabolites, as the end products of metabolism, are good indicators of the organism physiological status because under stresses, change in metabolites profiling represents the functional response of the organism. To this end a methodology has been developed for comparing the metabolome of coral from stressed and non stressed environments. We combined extraction of polar and nonpolar metabolites with three fundamental and complementary analytical techniques, GC-MS, LC-MS and NMR, to provide maximal coverage of the metabolome. We carried out bleaching experiments in controlled conditions on two scleractinian species by increasing the temperature or light irradiance. The methodology was tested in feasibility and validated and then used for the investigation of the coral metabolome from stress experience. After fingerprints acquisition and data preprocessing, multivariate statistical analyses (PCA, PLS-DA,…. ) were processed on the data to detect compounds that discriminate stressed and healthy corals
KERN, THIERRY. "Les effets extra-auditifs du bruit sur la sante : etat des connaissances en 1994." Strasbourg 1, 1994. http://www.theses.fr/1994STR15098.
Повний текст джерелаAmazirh, Abdelhakim. "Monitoring crops water needs at high spatio-temporal resolution by synergy of optical/thermal and radar observations." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30101.
Повний текст джерелаOptimizing water management in agriculture is essential over semi-arid areas in order to preserve water resources which are already low and erratic due to human actions and climate change. This thesis aims to use the synergy of multispectral remote sensing observations (radar, optical and thermal data) for high spatio-temporal resolution monitoring of crops water needs. In this context, different approaches using various sensors (Landsat-7/8, Sentinel-1 and MODIS) have been developed to provide information on the crop Soil Moisture (SM) and water stress at a spatio-temporal scale relevant to irrigation management. This work fits well the REC "Root zone soil moisture Estimates at the daily and agricultural parcel scales for Crop irrigation management and water use impact: a multi-sensor remote sensing approach" (http://rec.isardsat.com/) project objectives, which aim to estimate the Root Zone Soil Moisture (RZSM) for optimizing the management of irrigation water. Innovative and promising approaches are set up to estimate evapotranspiration (ET), RZSM, land surface temperature (LST) and vegetation water stress through SM indices derived from multispectral observations with high spatio-temporal resolution. The proposed methodologies rely on image-based methods, radiative transfer modelling and water and energy balance modelling and are applied in a semi-arid climate region (central Morocco). In the frame of my PhD thesis, three axes have been investigated. In the first axis, a Landsat LST-derived RZSM index is used to estimate the ET over wheat parcels and bare soil. The ET modelling estimation is explored using a modified Penman-Monteith equation obtained by introducing a simple empirical relationship between surface resistance (rc) and a RZSM index. The later is estimated from Landsat-derived land surface temperature (LST) combined with the LST endmembers (in wet and dry conditions) simulated by a surface energy balance model driven by meteorological forcing and Landsat-derived fractional vegetation cover. The investigated method is calibrated and validated over two wheat parcels located in the same area near Marrakech City in Morocco. In the next axis, a method to retrieve near surface (0-5 cm) SM at high spatial and temporal resolution is developed from a synergy between radar (Sentinel-1) and thermal (Landsat) data and by using a soil energy balance model. The developed approach is validated over bare soil agricultural fields and gives an accurate estimates of near surface SM with a root mean square difference compared to in situ SM equal to 0.03 m3 m-3. In the final axis a new method is developed to disaggregate the 1 km resolution MODIS LST at 100 m resolution by integrating the near surface SM derived from Sentinel-1 radar data and the optical-vegetation index derived from Landsat observations. The new algorithm including the S-1 backscatter as input to the disaggregation, produces more stable and robust results during the selected year. Where, 3.35 °C and 0.75 were the lowest RMSE and the highest correlation coefficient assessed using the new algorithm
Moch, Annie. "Aspects psychosociologiques des stress de l'environnement." Paris 8, 1987. http://www.theses.fr/1987PA080120.
Повний текст джерелаOur research belongs to the recent field of environmental psychology which studies inter-relational reactions between man and his environment. In the first three chapters, the link between environmental perception and stress in demonstrated. We suggest an acting model of stressor which shows that perceptive analysis is the first step in information processing mecanisms, from which disturbance and stress reactions can result afterward. We emphasize the significance of cognitive factors which mediate the perception of the environment, such as subjective factors (personality, motivation, intellectual resources,. . . ) or situational factors (controlability, social atmosphere,. . . ). Having synthesized the lastest researches on a specific stress i. E. : noise, our experiments have shown the valuable contribution of the behavioral patterns a and b to categorise individual's responses to noise nuisance. Other researches have demonstrated that spontaneous or induced adaptating strategies were developed. We have also observed the effect of noise on perception and on attitudes of the help to others. Finally, we have shown that social atmosphere acts upon noise-related stress
Marty, Vincent. "Adaptation de l'Archaea halophile halobacterium salinarum aux stress environnementaux : mécanismes de survie et rôle de la protéolyse intracellulaire." Thesis, Grenoble, 2011. http://www.theses.fr/2011GRENV087/document.
Повний текст джерелаMolecular systems described for Archaea show primitive and simple characteristics, compared to their homologous eukaryotes. In addition, extremophilic characteristic results in an hyper-robust which makes in vitro manipulation and structural studies much easier. Thus, Archaea represent good models for understanding complex cellular functions, particularly those that involve large molecular machines, such as those involved in proteolysis. My thesis consisted in understanding the resistance mechanisms and the importance of proteolytic systems in the adaptation of halophilic Archaea to environmental stresses. Halophilic Archaea accumulate multi-molar concentrations of KCl / NaCl in their cytosol (3.4M KCl / NaCl 1.1M for Halobacterium Salinarum). This requires a very special biochemistry that allows operation in solvents where free water is scarce. Thus, the proteins of these organisms are themselves halophilic and are soluble and folded only in extreme salinity conditions (2 to 5 M). This particular biochemistry partly explain the extraordinary ability of halophilic Archaea to resist physical and chemical stress (temperature, radiation, dehydration). We study the response of the halophilic Archaea strict H. salinarum at low-salinity stress. Indeed, beyond the osmotic shock, the fall of the environment salt concentration causes a decrease in the intracellular KCl concentration, which should have a direct effect on the folding state of intracellular protein, as in case of heat stress. In the first part of this thesis, a study was conduct to determine viability limits and cytosolic modifications, associated with a salinity decrease. These studies involve intracellular salt dosages, viability studies (microscopic counts, color live / dead), induction of chaperone proteins linked to stress response and biophysical neutron experiments, to evaluate the effect of stress on proteins folding. In this work, a phenomenon of survival at low salinity linked to morphological changes was revealed. To describe this phenomenon, this second study involves confocal microscopy experiences, fluorescence microscopy, viability tests, counting on box, scanning electron microscopy, electron microscopy by negative staining, salt intracellular dosages and proteins separation experiments, to study the overall proteome composition during low salinity stress. In this study, a fall of the intracellular K $^+$ concentration and the proteome clarification during stress was revealed. Low salt concentrations causes halophiles proteins denaturation, the accumulation of misfolded proteins in the cytoplasm involves chaperones systems and intracellular proteolysis machinery. In this context, another objective of my thesis was to contribute to the understanding of the intracellular proteolysis role in the PAN-proteasome system and in the aminopeptidase TET complex, in stress conditions established in previous studies. This part of the thesis involves experiments of endopeptidase activity assay, aminopeptidase activity assay, quantification of mRNA genic expression by Northern blot, immunoprecipitation, proteins separation by sucrose gradient and proteasome chemical inhibition (drug). We show the role of the PAN-proteasome system in stress response and we deepen our understanding of the aminopeptidase TET role in vivo. This protease appears to have an independent role of the proteasome complex. The protease TET seems to participate at the amino acids treatment in cells to maintain the metabolic activities in nutritional deficiencies
Adt, Isabelle. "Influence de facteurs environnementaux sur la physiologie et le métabolisme de SINORHIZOBIUM MELILOTI M5N1." Compiègne, 2002. http://www.theses.fr/2002COMP1421.
Повний текст джерелаRezaïki, Lahcen. "Métabolisme respiratoire chez Lactococcus lactis dans un environnement oxydant et identification de composants de la chaîne respiratoire." Paris 11, 2004. http://www.theses.fr/2004PA112133.
Повний текст джерелаLactococcus lactis is mainly used in the food industry, and has been mainly studied for its capacities to ferment sugar sources. Recently our laboratory discovered that l. Lactis are capable of a respiration metabolism when exogenous heme and oxygen are present in the medium. Respiration growth results in improved biomass, higher ph and a striking increased long term survival compared to fermentation metabolism. My thesis project was focused on the respiratory metabolism of l. Lactis, and principally addressed two objectives : the identification of respiratory chain components, and clarification of the factors that associate improved survival with respiration growth. We showed by mutagenesis that menaquinones function to assure electron transfer to cytochrome oxidase. We also demonstrate a role of menaquinones in generating superoxyde species, and in extracellular iron reduction. Our results suggest that nadh dehydrogenase noxa and noxb may be acting as electron donors for the respiration chain. The role of cytochrome bd oxidase, already known for its function as the only terminal oxidase in l. Lactis, was confirmed by our mutants cyda and cydb obtained by a random mutagenesis approach. Our results indicate that greater l. Lactis survival after respiration metabolism (compared to aeration growth in the absence of hème) is associated with, and likely due to a decrease in cytoplasmic oxidative stress and an increase of ph. The environment created by respiratory chain activity also improve the long term survival of fermenting bacteria present in the same medium
Rouan, Alice. "Étude des variations de la taille des télomères chez le corail Stylophora pistillata et dans les populations sauvages des genres Pocillopora sp., Porites sp., et Millepora sp. récoltés sur 32 systèmes insulaires de l’Océan Pacifique au cours de l’expédition TARA-Pacifique." Electronic Thesis or Diss., Université Côte d'Azur, 2020. http://theses.univ-cotedazur.fr/2020COAZ6050.
Повний текст джерелаThe linearity of eukaryotic chromosomes requires the presence of a particular terminal chromatin structure, named telomere, to control the stability and function of genomes. Changes in telomere structure during life can determine longevity, stress resistance and disease susceptibility. Our knowledge on the contribution of environmental factors on telomere length (TL) variability remains at its infancy, as well as the diversity of telomere maintenance mechanisms and ageing strategies existing in the tree of life. In this regard reef building corals are an interesting but yet poorly investigated model to tackle the question of telomere response to environment. Indeed those long lived animals cannot escape external environmental stressors due to their fixed life mode nor internal ones due to the symbiosis, within their gastrodermal cells, with a photosynthetic microalgae. Here I combined an extensive field case study on 3 coral genera (two scleractinians, Pocillopora sp. and Porites sp. and the hydrozoan Millepora sp.) as well as controlled conditions test on the coral model Stylophora pistillata to unravel the possible links between telomere DNA length variation and environmental stress. I found that an absence of TL shortening with age and size in all the investigated corals. I observed a possible impact of dark induced bleaching on TL and different TL dynamics in wild populations. Pocillopora sp. mean TL is constrained both by genetic and environment while Porites sp. has a remarkable ability to maintain its TL regardless of size, genetic and some environment disturbance. Yet both of genera TLs were negatively correlated with seasonal deviations, identifying this environmental parameter as a factor overcoming TL maintenance in genera with different TL dynamics and life-history strategies
Meillère, Alizée. "Influence de l’environnement urbain sur les passereaux : une approche éco-physiologique et éco-toxicologique." Thesis, La Rochelle, 2015. http://www.theses.fr/2015LAROS015/document.
Повний текст джерелаConsistent expanding urbanization is certainly among the most important human-induced environmental changes facing our planet today, and thus raises important questions regarding the consequences of such environmental disturbance on biodiversity. Urban life is often characterized by constraining environmental conditions (e.g., fragmentation, degradation and loss of habitats, increased noise, light, and chemical pollutions) that can have detrimental effects on wild vertebrates. However, the mechanisms through which urbanization affects wildlife are still poorly understood. In this context, the main objective of this doctoral research is to improve our understanding of the influence of urbanization on vertebrate species that are able to live in urban environments. To this end, we explored both the global influence of urbanization and the impact of specific factors associated with urban life (heavy metals and noise pollutions) on passerine birds, using a mechanistic approach including eco-physiological and eco-toxicological studies. We demonstrated that urban passerines are not energetically constrained by their environment during their adult life, but conversely, that the altered environmental conditions of urban environments could constrain individuals during their development. Furthermore, we showed that urbanization is indeed associated with an increased heavy metal contamination, and most importantly, that higher levels of these contaminants are related to higher corticosterone levels (i.e., elevated stress levels). Finally, using an experimental approach to study the impact of noise pollution on several parameters that have often been overlooked (development, physiology, anti-predator behaviour), we showed that anthropogenic noise can have particularly complex effects on vertebrate’s development, with possible life-long consequences for developing birds. Overall, our results emphasize the importance of investigating the impact of human-induced environmental changes on the phenotypic development of individuals to better understand the influence of urban environments on vertebrate populations
Vignaud, Timothée. "Production de forces par le cytosquelette d'actine : mécanismes et régulation par le micro-environnement." Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENY056/document.
Повний текст джерелаOur work has been focused on the regulation of the forces generated by the actin cytoskeleton. We have more precisely studied the role of the cellular microenvironment in this process. It was necessary to overcome some technical challenges to study these mechanisms. We developed two new techniques. The first one allows for the dynamic control of cell shape. A pulsed UV laser is used to modify the adhesive microenvironment around the cell and to create new area available for cell spreading. The second technique is an improvement of an existing technique from the laboratory. It consists in producing ECM protein islands on a elastic acrylamide substrate. This substrate provides the control of cell shape and internal organization. Plus, the elasticity of the substrate is compatible with traction forces measurements. The last technique combines acrylamide micropatterning and laser ablation of intracellular actin structures. Thus, the forces produced by a particular intracellular structure can be estimated. Two keys mechanisms of force regulation were shown. The use of mass spectrometry, traction force microscopy and molecular biology made it possible to study the interaction between different integrins in the adhesion complex. Cooperation was shown. It allows for the coupling between the architecture of the cytoskeleton and the amount of molecular motors in action. This process is necessary for the adaptation of cell forces to substrate stiffness. Actin structures are the one responsible for force production. This force can then be transmitted to the environment through adhesions.. The link between the length of actin fibers and the force produced was more precisely studied. The results showed a correlation between stress fibers length and the force generated inside it. This was true only above a certain critical value. After that, the force was rather decreasing with increasing fiber length. This critical length corresponds to the maximal length of cell axis on infinite 2D substrate. Our main hypothesis is that a too high myosin/actin ratio will block the proper force production/transmission within the fiber. Disassembly of actin by myosin or limited pool of actin are the two explanations we are currently following. The combination of these two-regulation process put brakes on force production by the cell. Above a certain length, the force produced is decreasing. This decreases in turn the strength of the adhesions anchored to these fibers. This will destabilize the adhesions and causes cell retraction The interplay between the regulation by the adhesion and the production of forces within the fiber set some limits on the level of forces produced by the cell. These processes are likely to be modified in a pathological context and can lead to tumor formation. They also protect the cell from being destroyed by stretching. If the length/stretch is too high, the cell will decrease its forces and detach from neighboring cells. This provide a system protecting the cell from being destroyed by massive deformations within the body