Rôle de CK2 dans la dynamique de la chromatine et la précision transcriptionnelle

La transcription par l’ARN polymérase II (ARNP II) est un mécanisme promiscuitaire à l’origine d’évènements transcriptionnels hasardeux, qui génèrent continuellement des transcrits aberrants dans la cellule. L’organisation précise du matériel génétique sous forme de chromatine est cruciale pour améliorer la précision de l’ARNP II en orientant sa fonction pour limiter ses erreurs et empêcher cette transcription cryptique. La structure chromatinienne est très dynamique et plusieurs mécanismes moléculaires coopèrent afin de déstabiliser les nucléosomes en amont de l’ARNP II, pour autoriser la lecture de l’ADN, et de les reconstituer dans son sillage, pour maintenir l’organisation chromatinienne du génome. De façon intéressante, une fonction potentielle de la caséine kinase 2 (CK2) dans la dynamique de la chromatine est suggérée dans la littérature. CK2 est une protéine kinase essentielle, conservée chez les eucaryotes, et impliquée dans des processus cellulaires variés. Dans notre étude, nous explorons le rôle de CK2 dans les modulations de la chromatine associées à la transcription. Nous avons démontré que CK2 phosphoryle le chaperon d’histones Spt6, régulant ainsi sa stabilité et sa fonction d’organisateur chromatinien. L’inactivation de cette voie de régulation conduit à l’accumulation considérable de transcrits cryptiques provenant d’initiations opportunistes intragéniques sens et antisens. La phosphorylation de Spt6 par CK2 favorise le recyclage des histones H3/H4 en 3’ des régions codantes et participe ainsi à la conservation de la structure de la chromatine lors de la transcription et à la suppression de la transcription cryptique. Notre étude suggère en outre que les fonctions de CK2 dans la modulation de la chromatine et la précision transcriptionnelle pourraient s’étendre au-delà de la régulation de Spt6, via la modulation de facteurs tels que les complexes PAF ou FACT. Enfin, nous proposons que la suppression de la transcription cryptique par CK2 contribue à optimiser la transcription afin d’améliorer la réponse transcriptionnelle à des stress extérieurs. L’ensemble de notre étude montre que CK2 stimule la précision transcriptionnelle en régulant directement Spt6 et probablement d’autres facteurs impliqués dans le maintien co-transcriptionnel de la chromatine. Ce mécanisme est crucial pour préserver le programme d’expression du génome et favorise la plasticité et l’efficacité de la réponse transcriptionnelle aux signaux de stress, nécessaires à l’adaptation de la cellule à son environnement.Transcription by RNA polymerase II (RNAPII) is pervasive and aberrant transcripts are permanently generated within cells. Precise and controlled genomic organization in chromatin structure is essential to improve RNAPII accuracy and prevent cryptic transcripts accumulation. Chromatin structure is highly dynamic during transcription, unfolded to give access to DNA and refolded back in the wake of RNAPII to prevent spurious transcription. Multiple mechanisms act together to make this process highly efficient. Casein Kinase 2 (CK2) is a protein kinase ubiquitously present among eukaryotes and implicated in various important cellular processes. Interestingly, a potential function of this kinase in chromatin dynamics through the regulation of chromatin factors has previously been suggested. In this study, we address the role of CK2 in chromatin modulations associated with transcription. We found that CK2 depletion from yeast cells results in an increase of histone turnover in 3’ of transcribed regions and spurious transcription from cryptic promoters. Interestingly, we demonstrate that CK2 modulates directly Spt6 histone chaperone stability and function. This regulation promotes histone recycling during transcription elongation and maintain chromatin organization within coding regions, thereby inhibiting cryptic intragenic and antisense transcription. Our study also suggests that CK2 suppression of spurious transcription extend beyond Spt6 regulation. Indeed, we describe that additional role of CK2 with respect to spurious transcription could be related to its regulation of RNAP II activity through CTD Ser2 phosphorylation. Chromatin regulators such as PAF complex and FACT could also be involved in this regulation process. Finally, we propose that CK2 suppression of spurious transcription is essential for transcriptional optimal and efficient responses to environmental signals. Altogether, our data highlights CK2 signaling pathway as a regulator of transcription accuracy by affecting the essential histone chaperone Spt6, and probably other factors directly involved in the transcriptional process. This mechanism is important to the suppression of cryptic transcription in steady state conditions but also seems to contribute to the fitness of an optimal cellular response to stress signals

Single and cumulative effects of whole-vine heat events on Shiraz berry composition

Aim: The aim of the study was to test the effect of a single heat event (HE), and the additive effects of repeated HEs at whole-vine level, on Shiraz berry composition, including detailed tannins. Methods and results: In a UV-transparent glasshouse, a system was developed to individually heat the above-ground parts of well-irrigated potted Shiraz vines without changing fruit and canopy light exposure. At the end of fruit set, and again prior to véraison, selected vines were heated to + 6 °C above ambient temperature for three consecutive days and nights in a combination of treatments to test the effect of a single HE and the additive effects of repeated HEs. A factorial design was used with four treatments (n=6): Control (C), heated at E-L 31 (HW1), heated at E-L 32 (HW2) and heated twice (HW1&2). Berries were sampled from fruit set until maturity at regular intervals, and primary and secondary metabolites, including detailed tannin composition, were analysed by GC-MS and LC-MS/MS, respectively. Temperatures (mean and maximum) inside the glasshouse were influenced by outside weather conditions and the 1st HE (HE1) was more intense than the 2nd (HE2). Photosynthesis was significantly decreased for the heated vines during HE1 where maximum temperature reached 45 °C, affecting both berry weight and titratable acidity (TA). HE2 was less intense with maximum temperature only reaching 40 °C, and had no effect on photosynthesis and less direct impact on composition. A few primary metabolites were affected by either HE1 or HE2 such as valine, leucine, pyruvic and lactic acids. Interactions between the two HEs were found for TA, malic acid and glucose at harvest. Skin tannin composition was significantly impacted by HE1, applied during the main biosynthesis period, but not by HE2. Epicatechin gallate terminal subunit concentration was the most impacted by heat. Seed physiology was also affected by HE1 and HE2 as well as seed tannin composition right after HE1. A small decrease in both total anthocyanins and total soluble solids at the end of véraison suggested that ripening was slightly delayed for HW1&2. Conclusions: Shiraz grapevines showed an elastic response to short heat stress between fruit set and véraison, with most impacts on physiology and composition observed during early post-treatment no longer evident by harvest. Significance and impact of the study: Increasing climate variability, with more frequent heatwaves, is a threat for viticulture in Australia where a large proportion of vineyards are located in already warm and hot regions. As grapevines may be exposed to abnormal high temperatures prior to véraison, knowledge on the effect of heat on metabolite biosynthesis occurring during this phase, such as tannins, is needed

Early Deformation of Deep Brain Stimulation Electrodes Following Surgical Implantation: Intracranial, Brain, and Electrode Mechanics

IntroductionAlthough deep brain stimulation is nowadays performed worldwide, the biomechanical aspects of electrode implantation received little attention, mainly as physicians focused on the medical aspects, such as the optimal indication of the surgical procedure, the positive and adverse effects, and the long-term follow-up. We aimed to describe electrode deformations and brain shift immediately after implantation, as it may highlight our comprehension of intracranial and intracerebral mechanics.Materials and MethodsSixty electrodes of 30 patients suffering from severe symptoms of Parkinson’s disease and essential tremor were studied. They consisted of 30 non-directional electrodes and 30 directional electrodes, implanted 42 times in the subthalamus and 18 times in the ventrolateral thalamus. We computed the x (transversal), y (anteroposterior), z (depth), torsion, and curvature deformations, along the electrodes from the entrance point in the braincase. The electrodes were modelized from the immediate postoperative CT scan using automatic voxel thresholding segmentation, manual subtraction of artifacts, and automatic skeletonization. The deformation parameters were computed from the curve of electrodes using a third-order polynomial regression. We studied these deformations according to the type of electrodes, the clinical parameters, the surgical-related accuracy, the brain shift, the hemisphere and three tissue layers, the gyration layer, the white matter stem layer, and the deep brain layer (type I error set at 5%).ResultsWe found that the implanted first hemisphere coupled to the brain shift and the stiffness of the type of electrode impacted on the electrode deformations. The deformations were also different according to the tissue layers, to the electrode type, and to the first-hemisphere-brain-shift effect.ConclusionOur findings provide information on the intracranial and brain biomechanics and should help further developments on intracerebral electrode design and surgical issues

Conception d’un dispositif neurochirurgical robotisé à base de matériaux actifs pour le suivi de trajectoire courbe

The goal of this thesis is to answer the following problem: To follow curved trajectories in the brain, in order to perform various neurosurgical operations. To answer this question, it is necessary to develop a robotic device able to progress in the brain, while meeting the constraints of neurosurgery.The first step is to define the constraints related to neurosurgery, as well as the objectives to be achieved. This leads to the definition of a list of requirements. To complete this list, it is necessary to answer another problem, that of defining the notion of curved trajectory in neurosurgery and to characterize a desired typical trajectory.An algorithm of generation of curved trajectories for neurosurgery, based on the use of Bézier curves, by integrating the operator and his knowledge is developed. Once the typical trajectory is created and validated by the surgeon, it is defined, thanks to the presetend criteria that we have established. These criteria were then transferred to the list of requirements to complete it.A bibliographical study about the materials qualified as active or intelligent materials is presented. The reflection allowing to choose the material allowing to answer in the best to the problematic and to the requirements.A second bibliographical study concerning the manufacturing of IPMCs is exposed, and leads to the design and the implementation of the manufacturing process. This manufacturing process is divided into two main steps, the shaping of the polymer by 3D printing and the creation of electrodes by electroless plating method. This process has allowed the production of several actuators of cylindrical shape. Locks remain to be solved to allow the actuation of the IPMCs manufactured.Even if some locks are still present, the preliminary results obtained are promising. A collaboration with specialists, in particular in chemistry, should lead to the production of functional actuators and so of the designed prototype.L’objectif de ces travaux de thèse est de répondre à la problématique suivante : Suivre des trajectoires courbes dans le cerveau, dans l’objectif de réaliser diverses opérations de neurochirurgie. Pour répondre à cela il est nécessaire de développer un dispositif robotisé capable de progresser dans le cerveau, tout en respectant les contraintes de la neurochirurgie.La première étape consiste à définir les contraintes liées à la neurochirurgie, ainsi que les objectifs à atteindre. Cela amène à la définition d’une liste des exigences. Pour compléter cette liste, il est nécessaire de répondre à une autre problématique, celle de définir la notion de trajectoire courbe en neurochirurgie et de caractériser une trajectoire type désirée.Un algorithme de génération de trajectoire courbe pour la neurochirurgie, basé sur l’utilisation de courbes de Bézier, en intégrant l’opérateur et son savoir dans le tracé, est développé. Une fois la trajectoire type créée et validée par le chirurgien, elle est définie, grâce à des critères que nous avons établis. Ces critères ont ensuite été reportés dans la liste des exigences afin de la compléter.Une étude bibliographique sur les matériaux dits actifs ou intelligents est présentée. La réflexion permettant de choisir le matériau permettant de répondre au mieux à la problématique et aux exigences posées.Une deuxième étude bibliographique sur la fabrication des IPMCs est exposée, et aboutit à la création ainsi qu’à la mise en place du procédé de fabrication. Ce procédé de fabrication se divisent en deux grandes étapes, la mise en forme du polymère par impression 3D et la création des électrodes par electroless plating method. Ce procédé a permis la production de plusieurs actionneurs de formes cylindrique. Des verrous restent à résoudre pour débloquer l’actionnement des IPMCs produits.Même si des verrous sont encore présents, les résultats obtenus sont prometteurs. Une collaboration avec des spécialistes, notamment en chimie, devrait conduire à la production d’actionneurs fonctionnelles et donc du prototype conçu

Design of a robotic neurosurgical device based on active materials for curved trajectory tracking

L’objectif de ces travaux de thèse est de répondre à la problématique suivante : Suivre des trajectoires courbes dans le cerveau, dans l’objectif de réaliser diverses opérations de neurochirurgie. Pour répondre à cela il est nécessaire de développer un dispositif robotisé capable de progresser dans le cerveau, tout en respectant les contraintes de la neurochirurgie.La première étape consiste à définir les contraintes liées à la neurochirurgie, ainsi que les objectifs à atteindre. Cela amène à la définition d’une liste des exigences. Pour compléter cette liste, il est nécessaire de répondre à une autre problématique, celle de définir la notion de trajectoire courbe en neurochirurgie et de caractériser une trajectoire type désirée.Un algorithme de génération de trajectoire courbe pour la neurochirurgie, basé sur l’utilisation de courbes de Bézier, en intégrant l’opérateur et son savoir dans le tracé, est développé. Une fois la trajectoire type créée et validée par le chirurgien, elle est définie, grâce à des critères que nous avons établis. Ces critères ont ensuite été reportés dans la liste des exigences afin de la compléter.Une étude bibliographique sur les matériaux dits actifs ou intelligents est présentée. La réflexion permettant de choisir le matériau permettant de répondre au mieux à la problématique et aux exigences posées.Une deuxième étude bibliographique sur la fabrication des IPMCs est exposée, et aboutit à la création ainsi qu’à la mise en place du procédé de fabrication. Ce procédé de fabrication se divisent en deux grandes étapes, la mise en forme du polymère par impression 3D et la création des électrodes par electroless plating method. Ce procédé a permis la production de plusieurs actionneurs de formes cylindrique. Des verrous restent à résoudre pour débloquer l’actionnement des IPMCs produits.Même si des verrous sont encore présents, les résultats obtenus sont prometteurs. Une collaboration avec des spécialistes, notamment en chimie, devrait conduire à la production d’actionneurs fonctionnelles et donc du prototype conçu.The goal of this thesis is to answer the following problem: To follow curved trajectories in the brain, in order to perform various neurosurgical operations. To answer this question, it is necessary to develop a robotic device able to progress in the brain, while meeting the constraints of neurosurgery.The first step is to define the constraints related to neurosurgery, as well as the objectives to be achieved. This leads to the definition of a list of requirements. To complete this list, it is necessary to answer another problem, that of defining the notion of curved trajectory in neurosurgery and to characterize a desired typical trajectory.An algorithm of generation of curved trajectories for neurosurgery, based on the use of Bézier curves, by integrating the operator and his knowledge is developed. Once the typical trajectory is created and validated by the surgeon, it is defined, thanks to the presetend criteria that we have established. These criteria were then transferred to the list of requirements to complete it.A bibliographical study about the materials qualified as active or intelligent materials is presented. The reflection allowing to choose the material allowing to answer in the best to the problematic and to the requirements.A second bibliographical study concerning the manufacturing of IPMCs is exposed, and leads to the design and the implementation of the manufacturing process. This manufacturing process is divided into two main steps, the shaping of the polymer by 3D printing and the creation of electrodes by electroless plating method. This process has allowed the production of several actuators of cylindrical shape. Locks remain to be solved to allow the actuation of the IPMCs manufactured.Even if some locks are still present, the preliminary results obtained are promising. A collaboration with specialists, in particular in chemistry, should lead to the production of functional actuators and so of the designed prototype

Conception d’un dispositif neurochirurgical robotisé à base de matériaux actifs pour le suivi de trajectoire courbe

The goal of this thesis is to answer the following problem: To follow curved trajectories in the brain, in order to perform various neurosurgical operations. To answer this question, it is necessary to develop a robotic device able to progress in the brain, while meeting the constraints of neurosurgery.The first step is to define the constraints related to neurosurgery, as well as the objectives to be achieved. This leads to the definition of a list of requirements. To complete this list, it is necessary to answer another problem, that of defining the notion of curved trajectory in neurosurgery and to characterize a desired typical trajectory.An algorithm of generation of curved trajectories for neurosurgery, based on the use of Bézier curves, by integrating the operator and his knowledge is developed. Once the typical trajectory is created and validated by the surgeon, it is defined, thanks to the presetend criteria that we have established. These criteria were then transferred to the list of requirements to complete it.A bibliographical study about the materials qualified as active or intelligent materials is presented. The reflection allowing to choose the material allowing to answer in the best to the problematic and to the requirements.A second bibliographical study concerning the manufacturing of IPMCs is exposed, and leads to the design and the implementation of the manufacturing process. This manufacturing process is divided into two main steps, the shaping of the polymer by 3D printing and the creation of electrodes by electroless plating method. This process has allowed the production of several actuators of cylindrical shape. Locks remain to be solved to allow the actuation of the IPMCs manufactured.Even if some locks are still present, the preliminary results obtained are promising. A collaboration with specialists, in particular in chemistry, should lead to the production of functional actuators and so of the designed prototype.L’objectif de ces travaux de thèse est de répondre à la problématique suivante : Suivre des trajectoires courbes dans le cerveau, dans l’objectif de réaliser diverses opérations de neurochirurgie. Pour répondre à cela il est nécessaire de développer un dispositif robotisé capable de progresser dans le cerveau, tout en respectant les contraintes de la neurochirurgie.La première étape consiste à définir les contraintes liées à la neurochirurgie, ainsi que les objectifs à atteindre. Cela amène à la définition d’une liste des exigences. Pour compléter cette liste, il est nécessaire de répondre à une autre problématique, celle de définir la notion de trajectoire courbe en neurochirurgie et de caractériser une trajectoire type désirée.Un algorithme de génération de trajectoire courbe pour la neurochirurgie, basé sur l’utilisation de courbes de Bézier, en intégrant l’opérateur et son savoir dans le tracé, est développé. Une fois la trajectoire type créée et validée par le chirurgien, elle est définie, grâce à des critères que nous avons établis. Ces critères ont ensuite été reportés dans la liste des exigences afin de la compléter.Une étude bibliographique sur les matériaux dits actifs ou intelligents est présentée. La réflexion permettant de choisir le matériau permettant de répondre au mieux à la problématique et aux exigences posées.Une deuxième étude bibliographique sur la fabrication des IPMCs est exposée, et aboutit à la création ainsi qu’à la mise en place du procédé de fabrication. Ce procédé de fabrication se divisent en deux grandes étapes, la mise en forme du polymère par impression 3D et la création des électrodes par electroless plating method. Ce procédé a permis la production de plusieurs actionneurs de formes cylindrique. Des verrous restent à résoudre pour débloquer l’actionnement des IPMCs produits.Même si des verrous sont encore présents, les résultats obtenus sont prometteurs. Une collaboration avec des spécialistes, notamment en chimie, devrait conduire à la production d’actionneurs fonctionnelles et donc du prototype conçu

Grape Berry Flavonoid Responses to High Bunch Temperatures Post Véraison: Effect of Intensity and Duration of Exposure

Climate models predict an increase in the frequency and duration of heatwaves with an increase in intensity already strongly evident worldwide. The aim of this work was to evaluate the effect of two heatwave-related parameters (intensity and duration) during berry ripening and identify a threshold for berry survival and flavonoid accumulation. A Doehlert experimental design was used to test three temperature intensities (maxima of 35, 46, and 54 °C) and five durations (3 to 39 h), with treatments applied at the bunch level shortly after véraison. Berry skin and seeds were analysed by liquid chromatography-triple quadrupole-mass spectrometry (LC-QqQ-MS) for flavonoids (flavonols, anthocyanins, free flavan-3-ols, and tannins). Berries exposed to 46 °C showed little difference compared to 35 °C. However, berries reaching temperatures around 54 °C were completely desiccated, and all flavonoids were significantly decreased except for skin flavonols on a per berry basis and seed tannins in most cases. Some compounds, such as dihydroxylated flavonoids and galloylated flavan-3-ols (free and polymerised), were in higher proportion in damaged berries suggesting they were less degraded or more synthesised upon heating. Overall, irreversible berry damages and substantial compositional changes were observed and the berry survival threshold was estimated at around 50–53 °C for mid-ripe Shiraz berries, regardless of the duration of exposure

Addictions et médecine générale (bases théoriques du travail relationnel et des psychothérapies)

TOURS-BU Médecine (372612103) / SudocSudocFranceF

Acta Hortic.

Optimisation of nitrogen (N) supply and other nutrients in vineyards is critical to quality and quantity of fruit and wine production. However, there are major challenges to balance N availability for canopy growth in spring, reproductive development, fruit maturity rates and optimum grape composition at harvest. Therefore, frequent monitoring of nutrient status is essential to better predict and target inputs and consequentially maximise profitability. Rapid and convenient assessment of grapevine N status in the field can help identify N requirements during the season. A replicated experiment was undertaken in a glasshouse using two-year-old ‘Shiraz’ vines from dormancy to veraison that were pruned back to four two-bud spurs. The vines were previously water stressed, re-potted in washed river sand and then placed into a cool room at approximately 5-6°C for 14 days. From the end of dormancy, different nutrient solutions were applied to create a range of leaf nutrient levels for N, supplying approximately 100, 50 and 0% of N required for the bud burst to veraison period. Spectrometer measurements (reflectance) and leaf samplings were conducted at three times (at flowering, four weeks before and after) and three locations along the shoots (opposite the basal bunch, and two and four nodes above the basal bunch). The leaves were washed, separated into blades and petioles, ground and analysed for N concentration. The reflectance, particularly around 550 nm, showed considerable difference between N treatments, and these were more pronounced on the older leaves and later in the season. Leaf and petiole N concentrations were closely related, allowing the calibration of the indirect measurements with a spectrometer to establish petiole standards for flowering. Better understanding of changes in leaf N concentrations during vine development will allow for more accurate predictions of N requirements throughout the growing season