Dissertationen zum Thema „Effet de position télomérique“
Geben Sie eine Quelle nach APA, MLA, Chicago, Harvard und anderen Zitierweisen an
Machen Sie sich mit Top-20 Dissertationen für die Forschung zum Thema "Effet de position télomérique" bekannt.
Neben jedem Werk im Literaturverzeichnis ist die Option "Zur Bibliographie hinzufügen" verfügbar. Nutzen Sie sie, wird Ihre bibliographische Angabe des gewählten Werkes nach der nötigen Zitierweise (APA, MLA, Harvard, Chicago, Vancouver usw.) automatisch gestaltet.
Sie können auch den vollen Text der wissenschaftlichen Publikation im PDF-Format herunterladen und eine Online-Annotation der Arbeit lesen, wenn die relevanten Parameter in den Metadaten verfügbar sind.
Sehen Sie die Dissertationen für verschiedene Spezialgebieten durch und erstellen Sie Ihre Bibliographie auf korrekte Weise.
Boussouar, Amina. „Effet de position télomérique et criblage moléculaire : vers de nouvelles cibles télomériques“. Lyon, Ecole normale supérieure, 2010. http://www.theses.fr/2010ENSL0597.
Der volle Inhalt der QuelleTelomeres are protective structures present at the ends of linear chromosomes and consist of simple repeated DNA sequences and specialized proteins. They are essential for the stable maintenance of eukaryotic chromosomes and they can regulate the lifespan of cells. In addition to their essential functions, telomeres are, in diverse organisms, specialized sites with regard to gene expression. Indeed, the transcription of genes located next to telomeres is repressed: this phenomenon was termed telomere position effect (TPE). As observed in the yeast, S. Cerevisiae -where TPE is best characterized- TPE in human cells depends of both telomere length and architecture. The treatment of cells with Trichostatin A, an inhibitor of class I and II histone deacetylases antagonizes TPE while treating the cells with 5-aza-2’-deoxycytidin, a demethylating agent, has no apparent effect on telomeric repression. Overall, position effects at human chromosome ends are dependent on a specific higher-order organization of the telomeric chromatin. In order to identify new molecules able to modulate TPE in human cells, we carried out the screening of the «Prestwick Chemical Library », a bank of bioactive molecules, on the CMBA-CEA platform in Grenoble. A total of 15 molecules were identified as anti-TPE factors after primary and secondary screening based on the increase in fluorescence measurement. After testing all of these molecules in our laboratory, two polyphenols, Acacetin and Chrysin, were retained as potent inhibitors of TPE and further characterized as drugs targeting telomeres specifically. We then asked whether TPE reversal was dependent on telomere length. The incubation in the presence of Acacetin and Chrysin affects telomere length suggesting that increased expression of the subtelomeric reporters is associated with a shortening of telomeres. To check whether these molecules revert telomeric silencing, by affecting telomere integrity, we analyzed chromosome stability in cells treated with Acacetin or Chrysin. The two molecules exhibit a rapid increase in the frequency of telomere induced DNA damage foci, suggesting that these drugs trigger telomeric dysfunction. Drug treatment also significantly increases the frequency of telomeric abnormalities observed in metaphase with a significant increase of end-to-end fusions between sisters chromatid. The discovery of these new compounds targeting specifically chromosome ends opens new avenue for the targeted treatment of diseases linked to telomeric pathways such as cancer but also rare diseases such as Facio-Scapulo-Humeral dystrophy for which we investigated the molecular mechanisms
Rey-Millet, Martin. „Les télomères, des éléments de régulation de la transcription dans les cellules sénescentes“. Electronic Thesis or Diss., Université Côte d'Azur, 2021. http://www.theses.fr/2021COAZ6022.
Der volle Inhalt der QuelleTelomeres, the nucleoprotein structures located at the end of eukaryotic DNA, protect chromosomal integrity. These structures undergo changes during development and aging, including length shortening and alterations in the levels of the proteins associated to them called sheltering, all this affecting genome stability as the cells age. However, telomeres also behave as transcriptional regulators acting not only on genes present at subtelomeres but also on more distantly located genes presented throughout the genome. This process is referred as Telomere Position Effect (TPE) and was initially discovered in budding yeast, but also seen in drosophila, fission yeast, plasmodium and more recently in humans. In all these organisms, genes located in the subtelomeres are repressed by an epigenetic mechanism that is dependent on telomere DNA length, telomere nucleoprotein composition and higher order chromatin organization adopted by telomeres and subtelomeres. The TPE mechanism can be described as the spreading of a heterochromatin-like structure toward the centromere most likely accompanied by the formation of large chromatin loops to further extend the transcriptional regulation emanating from a telomere to genes internally located.In this context, the goal of my thesis is to decipher whether telomeres are involved in the transcriptional remodelling occurring in human cellular senescence. For that, we performed RNA-sequencing in young versus replicative senescent lung fibroblast MRC-5 cells. Interestingly, we found an enrichment of upregulated genes in the subtelomeric regions of senescent cells suggesting a TPE alleviation. This alleviation is not homogeneous in the genome, as only some subtelomeres were enriched in upregulated genes at senescence.Finally, we tested the hypothesis that shelterin proteins may also be part of the TPE regulation. For that, we re-stored the levels of the shelterin protein TRF2 (Telomeric Repeat Binding Factor 2) whose expression is decreased as the cells approach senescence. We found that TRF2 is indeed modulating the expression of subtelomeric genes in senescent cells, and this is in part mediated by a long-range chromatin reorganization of subtelomeres as observed by conformation changes in 3D chromatin conformation by FISH.Overall, this work reveals the contribution of telomeres in the transcriptional program of senescent cells and set the basis for the relevance of TPE in the senescence/aging process
Adamian, Nika. „Predictive position coding : attentional account of motion-induced position shifts“. Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCB164/document.
Der volle Inhalt der QuelleLocalizing objects in space is one of the central functions of the visual system. When an observer or a target is moving, the motion of the eye or the object can be taken into account to compute the current object locations. It has been shown many times that visual motion can strongly influence the perceived position of an object. For example, a stationary patch containing moving texture (De Valois & De Valois, 199; Ramachandran & Anstis, 1990), a flash presented on (Cavanagh & Anstis, 2013) or next to (Whitney & Cavanagh, 2000) a moving texture, and even the onset and offset positions of the moving targets (Fröhlich, 1923) are perceived as shifted in the direction of motion. In this thesis we explore the relationship between these motion-induced position shifts and visual attention in the following forms: 1) transient spatial attention, 2) global and local attention, 3) sustained spatial attention, and 4) object-based attention. In the first series of experiments we looked at whether and how attention modulates the shift in localization of motion onset (Fröhlich effect). In Experiments 1 and 2 we measured Fröhlich effect under different cueing conditions and established that invalid or late cues produced larger perceptual shifts. In Experiment 3 we compare the motion-induced shifts when the subjects attended to a set of moving stimuli as a group and when they attended to an orientation singleton. We showed that the Fröhlich effect was only present when the target was individuated and disappeared when the stimulus was perceived globally. Thus, the Fröhlich effect appeared to be both produced and modulated by focal attention. Having established that temporal delays of attention increase motion-induced position shifts, the next study explored if spatial distribution of attention has a similar effect. In this study we used flash grab - an illusory position shift seen when a target is briefly flashed on top of a moving background that abruptly changes direction (Cavanagh & Anstis, 2013). Trials were presented in blocks and before each block a cue indicated a range of possible target locations. We found that the flash grab was reduced if the spatial distribution of targets was limited to a range of 90° or less. The final study asked whether motion shifts the perceived position of an object as a whole or if separate features of a single object are shifted independently. To test this we used the flash grab paradigm and briefly presented a shape on top of a moving background at the moment it changed direction. The results showed that the features of the target that were orthogonal to the background motion were shifted, whereas the features parallel to the motion were intact. This suggests that motion interacts with the position of the object's features (and focal attention selects them) before they are bound together into an object. In conclusion, we applied a variety of attentional manipulations to motion-induced position shifts, and examined the link between the strength of the illusion and the characteristics of attention used in a particular task. We found that 1) motion-induced position shifts require focused attention and the possibility to track an individual motion trajectory; 2) allowing attention to be allocated more efficiently in space reduces the illusion; and 3) motion-induced shifts operate on the feature-based and not object-based level
Moraine, Jean-Jacques. „Le débit sanguin cérébral dans les affections neurologiques aiguës: effet de la position“. Doctoral thesis, Universite Libre de Bruxelles, 2001. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211594.
Der volle Inhalt der QuellePeltier, Jean-David. „Isomères de position d’indacénodithiophènes : synthèse, propriétés et applications en transistors organiques à effet de champ“. Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1S138/document.
Der volle Inhalt der QuelleOrganic Field Effect Transistors (OFETs), in which the charge transport is carried through a thin film made of organic molecules represent a transformation of the FET technology regarding that based on Silicon. They offer in particular the possibility to manufacture low cost flexible electronics. This work is focused on the synthesis, the study and the use as active layer in n-type OFETs of novel, electron poor, couples of para- and meta-indacenodithiophenes isomers (para- and meta-IDT). First of all, an introduction to the field of n-type OFETs is presented, followed by the presentation of the synthesis of the IDT derivatives and the comparative analysis of their properties. Finally, the fabrication of the OFETs, their characterization and the optimization of their architecture is described. The performances recorded attest that these derivatives are of great interest for the n-type OFETs. Different 3π-2spiro IDT derivatives are also presented in order to study the IDTs intrinsic properties and to envisage their incorporation as host in phosphorescent organic light-emitting diodes
Haddad, Darine. „Mesure et contrôle de position et de vitesse à l'échelle nanométrique : application à la balance du watt“. Versailles-St Quentin en Yvelines, 2004. http://www.theses.fr/2004VERS0018.
Der volle Inhalt der QuelleThe aim of this work is to control the position and the velocity of a moving mass with a nanometric accuracy on a translation range of 80 mm. For the velocity, the objective is to obtain a stability of 10-9 in relative value. The essential application is the watt balance of the Bureau National de Métrologie. A novel method was developed and implemented, based on the use of both a heterodyne Michelson's interferometer and a home made electronic circuit. The interferometric system is associated to a mechanical system of double translation stages made up of a linear stage and a piezoelectric actuator. Displacement of 4. 945 nm was controlled and measured with repeatabilities and accuracies less than the nanometer. Results show that relative uncertainty of 10-9 on velocity can be reached
Lecomte, Vincent. „Préparation d'androst-5-ènes modifiés en position 11 via l'étude de la réactivité de cétones énolisables et d'alcools tertiaires en série encombrée“. Phd thesis, Paris 6, 2004. http://pastel.archives-ouvertes.fr/pastel-00001108.
Der volle Inhalt der QuelleBarbot, Willy. „Variation circadienne et induction avec l'âge de l'expression d'un rétrotransposon IAP de souris : caractérisation du site d'insertion proviral et "effet de position"“. Paris 6, 2002. http://www.theses.fr/2002PA066022.
Der volle Inhalt der QuelleIannuzzi, Stéphanie. „Les effets lexicaux dans l'identification de la lettre : étude en potentiels évoqués chez des enfants normo-lecteurs et dyslexiques“. Toulouse 3, 2010. http://thesesups.ups-tlse.fr/1276/.
Der volle Inhalt der QuelleOrthographic processes that take place during visual recognition of letter sequences can be dissociated into three different stages activated in an interactive and parallel manner : visual feature analysis, letter processing and letter sequence processing. The lexical influences on letter identification have often been observed with the well-known Word Superiority Effect : a letter is better identified when presented in words than in non-words or in isolation. One aim of this study was to understand which processing stages are influenced by lexical knowledge during reading acquisition. To do this, we performed an Event-Related Potential study with dyslexic children and typically achieving ones. The task consists in identifying a letter presented in a word or a non-word. Furthermore, it is well accepted that, in alphabetic and left-to-right languages, words are better identified when fixated slightly left of the center. Our task was designed in such a way that we were able to study this Optimal Viewing Position. The aim was to analyse if the lexical influences intervene in the same manner for all position in the word. Our behavioral results show a Word Superiority Effect only for typically achieving children suggesting influences of the lexical knowledge for them. We hypothesise that dyslexics present a deficit on these "top-down" lexical influences. Analyses based on the position do not show the Optimal Viewing Position expected. The results are similar in both groups with a diminution of the performance between the first and the last position. It suggests a serial and automatic processing of the stimuli from left to right whatever the fixation point. The firsts ERPs differences between words and non-words appears on the N2 reflecting the lexical processing and the same effect is shown in both groups. The lack of effect on the N170 is in disagreement with the hypothesis of lexical influences on letter identification at a pre-lexical level
Guillemot, Laurent. „Les processus de captures électroniques multiples par des ions multichargés lors de collisions sur des cibles atomiques neutres : étude critique du modèle moléculaire de la barrière coulombienne“. Paris 11, 1989. http://www.theses.fr/1989PA112380.
Der volle Inhalt der QuelleAndersson, Frédéric. „Effet de la position oculaire sur l’activité de l’aire visuelle primaire sur l’Homme : étude en Potentiels Evoqués Visuels et en imagerie par résonance magnétique fonctionnelle“. Caen, 2005. http://www.theses.fr/2005CAEN2004.
Der volle Inhalt der QuelleLevi, Loïc. „Comportements d'investissement et performances des exploitations agricoles selon la position dans le cycle de vie“. Thesis, Rennes, Agrocampus Ouest, 2018. http://www.theses.fr/2018NSARE053/document.
Der volle Inhalt der Quelle: Investment and innovation play an important role in the agricultural sector, allowing farms to adapt to policy changes and market condition changes. In the last decades, farms in the European Union (EU) have faced substantial changes in the Common Agricultural Policy (CAP). This is particularly the case of the dairy sector, which has seen the end of milk quota regime and increased price volatility. Such changes could affect farm productivity and efficiency, the dairy sector’s competitiveness and structural change. Understanding the mechanisms underlying farms’ investment behaviour could allow identifying key drivers that influence the observed trends. This could help anticipate future structural changes, predict farms’ needs and help policy makers and other stakeholders in farming to adapt their policy. The thesis contributes to this objective by analysing for dairy farms in a sub-region of Brittany (Ille-et-Vilaine) in France, (i) the impact of the termination of the milk quota onfarmers’ investment decisions and the heterogeneity of farm investment behaviour, (ii) the link between farm performance and farmers’ investment decisions, (iii) the role of social interactions related to neighbourhood effects on farmers' investment decision. Findings show that the termination of the dairy quota policy increased farmers’ incentive to invest, contributing to the trend towards larger, more capital intensive and more specialised dairy farms. In addition, the thesis underlines the need to take into account farmers’ heterogeneity in modelling investment behaviour. Doing so allows
Lapointe, Julie. „Effet d'interaction entre les facteurs de risque posturaux et psychosociaux de l'environnement de travail sur la survenue des symptômes musculosquelettiques chez les utilisateurs de poste informatique“. Thesis, Université Laval, 2008. http://www.theses.ulaval.ca/2008/25661/25661.pdf.
Der volle Inhalt der QuelleOBJECTIVE: To investigate interaction between psychosocial and postural work factors on the incidence of self-reported musculoskeletal symptoms among a group of white-collar workers. METHODS: Psychosocial and postural work factors were assessed in a cohort of 2,431 white-collar workers (baseline participation: 76%, follow up participation: 91%). The job strain (Karasek’s) model and the effort-reward (Siegrist’s) model were used to characterize the psychosocial work environment. Postural factors related to Visual Display Unit work were assessed using a self-report questionnaire. Three years later, the incidence proportion of musculoskeletal symptoms at three different anatomical sites (shoulder-neck, lower back, and upper limbs) was estimated with a modified version of the Nordic questionnaire. Analyses were stratified for gender. Interaction was defined as a departure from the addition of individual risk factors and its importance was estimated with the attributable proportion due to interaction and its 95% interval. RESULTS: A significant interaction between job strain and postural factors was observed for men for the lower back. Two significant interactions between effort-reward and postural factors were observed for women in the shoulder-neck and the upper limbs regions. Several indications of interaction between psychosocial and postural work factors were observed. CONCLUSION: The simultaneous presence of postural and psychosocial risk factors seems to increase the individual pathogenic effect of each risk factor on the incidence of musculoskeletal symptoms. This interaction effect is of primary importance for work intervention practices as it means that succeeding to reduce anyone of these two risk factors will likely have the additional benefit to reduce the interaction effect of the incidence proportion of musculoskeletal symptoms.
Inscrite au Tableau d'honneur de la Faculté des études supérieures
Julien, Maxime. „Détermination des effets isotopiques position-spécifiques (PSIA) par RMN quantitative isotopique du carbone-13 et modélisation de la remédiation du méthyl tert-butyl éther (MTBE)“. Nantes, 2015. https://archive.bu.univ-nantes.fr/pollux/show/show?id=6e36186b-c859-42f3-87dc-30b7bfcff8b7.
Der volle Inhalt der QuelleBetter methodologies appear to be necessary for detecting the origins of given pollutants, and for understanding the natural processes involved in their migration routes, biodegradation and eventual disappearance. In addition, it is essential to check whether treatment leads to complete mineralization or if cleaning of the polluted area is effective. Isotopic measurement is a fundamental tool that can be used in the management of a pollution to provide indicators as to containment, spread and bioremediation possibilities is proposed in the ISOTO-POL project. As a complete illustration of this principle, MTBE, which is frequently detected in surface and ground water, is given as an example. Stable isotopes have been used successfully to demonstrate the natural or enhanced biodegradation of petroleum hydrocarbons, solvents, and gasoline additives in soil and groundwater. So far, overall isotopic fractionation in 13C has been exploited, the isotope content being measured by isotope ratio mass spectrometry (irm-MS), but this leads to the loss of valuable position-related information. In contrast, NMR spectrometry offers the capability to measure position-specific 13C/12C ratios, giving new information. Isotopic NMR methodology will allow to determine position-specific isotope effects involved in physical transformations (volatilization and migration), chemical (hydrolysis and oxidation) as well as degradation by microorganisms. The construction of a model will provide a unique means to allow detailed detection and tracing of a given pollutant and the determination of its origin as well
Aliakbari, khoei Mina. „Une approche computationnelle de la dépendance au mouvement du codage de la position dans la système visuel“. Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4041/document.
Der volle Inhalt der QuelleCoding the position of moving objects is an essential ability of the visual system in fulfilling precise and robust tracking tasks. This thesis is focalized upon this question: How does the visual system efficiently encode the position of moving objects, despite various sources of uncertainty? This study deploys the hypothesis that the visual systems uses prior knowledge on the temporal coherency of motion (Burgi et al 2000; Yuille and Grzywacz 1989). We implemented this prior by extending the modeling framework previously proposed to explain the aperture problem (Perrinet and Masson, 2012), so-called motion-based prediction (MBP). This model is a Bayesian motion estimation framework implemented by particle filtering. Based on that, we have introduced a theory on motion-based position coding, to investigate how neural mechanisms encoding the instantaneous position of moving objects might be affected by motion. Results of this thesis suggest that motion-based position coding might be a generic neural computation among all stages of the visual system. This mechanism might partially compensate the accumulative and restrictive effects of neural delays in position coding. Also it may account for motion-based position shifts as the flash lag effect. As a specific case, results of diagonal MBP model reproduced the anticipatory response of neural populations in the primary visual cortex of macaque monkey. Our results imply that an efficient and robust position coding might be highly dependent on trajectory integration and that it constitutes a key neural signature to study the more general problem of predictive coding in sensory areas
Schneider, Anne. „Contribution à l'étude des propriétés du phosphate de vanadyle“. Phd thesis, Bordeaux 1, 1987. https://tel.archives-ouvertes.fr/tel-00374010.
Der volle Inhalt der QuelleBlanco, Oscar. „Dynamique des faisceaux dans la section finale de focalisation du futur collisionneur linéaire“. Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112108/document.
Der volle Inhalt der QuelleThe exploration of new physics in the “Tera electron-Volt” (TeV) scale with precision measurements requires lepton colliders providing high luminosities to obtain enough statistics for the particle interaction analysis. In order to achieve design luminosity values, linear colliders feature nanometer beam spot sizes at the Interaction Point (IP).Three main issues to achieve the beam size demagnification in the Final Focus Section (FFS) of the accelerator are the chromaticity correction, the synchrotron radiation effects and the correction of the lattice errors.This thesis considers two aspects for linear colliders: push the limits of linear colliders design, in particular the chromaticity correction and the radiation effects at 3 TeV, and the instrumentation and experimental work on beam stabilization in a test facility.A new chromaticity correction scheme, called non-interleaved, is proposed to the local and non-local chromaticity corrections for CLIC. This lattice is designed and diagnosed, where the main issue in the current state of lattice design is the non-zero second order dispersion in the Final Doublet (FD) region where a strong sextupole is used to correct the remaining geometrical components.The radiation effect can be evaluated by tracking particles through the lattice or by analytical approximations during the design stage of the lattices. In order to include both, radiation and optic parameters, during the design optimization process, two particular radiation phenomena are reviewed: the Oide effect and the radiation caused by bending magnets .The analytical result of the radiation in bending magnets in was generalized to the case with non-zero alpha and non-zero dispersion at the IP, required during the design and luminosity optimization process. The closed solution for one dipole and one dipole with a drift is compared with the tracking code PLACET, resulting in the improvement of the tracking code results.The Oide effect sets a limit on the vertical beamsize due to the radiation in the final quadrupole. Only for CLIC 3 TeV this limit is significant, therefore two possibilities are explored to mitigate its contribution to beam size: double the length and reduce the QD0 gradient, or the integration of a pair of octupoles before and after QD0.Part of the requirements of the FFS for new linear accelerators are tested in The Accelerator Test Facility (ATF). The beam size reduction using the local chromaticity correction is explored by an extension of the original design, called ATF2 with two goals: achieve 37 nm of vertical beam size at the IP, and the stabilization of the IP beam position at the level of few nanometres. Since 2014 beam size of 44 nm are achieved as a regular basis at charges of about 0.1 × 10^10 particules per bunch.A set of three cavities (IPA, IPB and IPC), two upstream and one downstream of the nominal IP and on top of separate blocks of piezo-electric movers, were installed and are used to measure the beam trajectory in the IP region, thus providing enough information to reconstruct the bunch position and angle at the IP. These will be used to for beam stabilization and could detect beam drift/jitter beyond the tolerable margin and undetected optics mismatch affecting the beam size measurements. The specifications required of 1 nm resolution over 10 μm dynamic range at 1.0 × 10 10 particules per bunch with the ATF2 nominal optics have not been yet achieved.The minimum resolution achieved is just below 50 nm at 0.4 × 10^10 particules per bunch with a set of electronics impossing a noise limit on resolution of 10 nm per cavity. The dynamic range is 10 μm at 10 dB attenuation and 0.4 × 10^10 particules per bunch, indicating the need to upgrade theelectronics. The integration to the ATF tuning instruments is ongoing. Nonetheless, feedback has been tested resulting in reduction of beam jitterdown to 67 nm, compatible with resolution
Senécal, Julie. „Effet des variétés de position de la tête du foetus sur le travail obstétrical chez les nullipares sous analgésie péridurale /“. 2004. http://proquest.umi.com/pqdweb?did=766835901&sid=10&Fmt=2&clientId=9268&RQT=309&VName=PQD.
Der volle Inhalt der QuelleLemelin, Jean-François. „Évaluation du rôle de p53 dans la régulation de la recombinaison homologue et la stabilité génomique“. Thèse, 2004. http://hdl.handle.net/1866/15560.
Der volle Inhalt der QuelleVillandré, Luc. „Effet de l'échantillonnage non proportionnel de cas et de témoins sur une méthode de vraisemblance maximale pour l'estimation de la position d'une mutation sous sélection“. Thèse, 2008. http://hdl.handle.net/1866/8196.
Der volle Inhalt der Quelle