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Rôle de l'Autophagie Médiée par les Chaperonnes dans la régénération du cœur
No full textInternational audienceMyocardial infarction (MI), a coronary heart disease, is a leading cause of death worldwide. Following such an injury, the damaged tissue is replaced by a noncontractile fibrotic scar, causing pathological tissue restructuring and ultimately heart failure. Current medical treatments can delay post-infarction pathophysiological remodeling but fail to re-establish new functional myocardium. Adult zebrafish have the unique ability to regenerate their heart after different insults, including cryoinjury - a method that recapitulates key post-infarction events including tissue death, fibrosis, and scarring in a localized manner. Recent data emphasize the importance of metabolic reprogramming to support regeneration. After cardiac damage, the cellular metabolism switches from oxidative to glycolytic which is critical to support endothelial cell (EC) and cardiomyocyte (CM) regeneration. Late studies show that manipulation of metabolic enzymes to enhance glycolysis is sufficient to promote adult CM proliferation in zebrafish and mice.Chaperone-mediated Autophagy (CMA), a major pathway of lysosomal proteolysis, is critical for cellular homeostasis and metabolism. It targets a specific amino acid sequence within proteins (KFERQ motif), thereby selectively remodeling the proteome. Targets include key carbohydrate and lipid metabolism enzymes. My pioneering PhD work was one of the first to identify CMA in fish, revealing its role in metabolic processes. Here we hypothesize that CMA activation plays a key role during heart regeneration by regulating the cardiac metabolic switch after injuryFirstly, we focused on assessing CMA status in heart regeneration. To this end, we measured lamp2a expression, the rate-limiting factor of CMA, in zebrafish heart at different timepoints after cardiac cryoinjury. Our results indicate a gradual activation of lamp2a, with a peak at 4 days post-cryoinjury. We confirmed this upregulation by high resolution in situ hybridization for lamp2a .Our current efforts are focused on investigating the impact of CMA loss- and gain-of-function on heart regeneration using new genetic models.Overall, this study will help understand the role of CMA in metabolic reprograming during heart regeneration, having the potential to inform new MI therapies
Juveniles at risk: behaviour and colour changes in sole juveniles (Solea solea) after exposure to estuarine ragworms (Hediste diversicolor) contaminated with microplastics
No full textInternational audienceDue to strong anthropogenic pressures and their location at the interface between continental and oceanic environments, estuarine areas are affected by significant diverse pollution and species that live in these areas are particularly exposed. Microplastic (MPs) pollution is a worldwide issue and causes substantiated trouble in estuaries where sometimes the number of MPs equal or exceed the number of fish larvae which suggest a high risk of contamination of biota especially in benthic organisms and demersal fish. There are growing evidence that, beyond intrinsic toxicity, MPs can transfer chemicals (additives or pollutants). In order to get closer to environmental situations, in this study we tackled an issue that is rarely dealt with, namely the trophic transfer of MPs and chemicals through the food chain between a sediment- and a benthic-feeder. To take into account these specificities, we used an emblematic and common species of the European coastlines, the common sole (Solea solea) and its annelid prey.Sole juveniles were fed with estuarine ragworms (Hediste diversicolor) previously exposed to MPs via enriched MPs sediment. The MPs used were either a mixture of micronized plastics collected from the Seine Estuary (eMPs, two environmental concentrations at 1 or 100 mg/kg of sediment, median size range 52-77 μm) or model MPs of PVC particles (at 1 g/kg of sediment, size range 125-250 μm), either uncontaminated or contaminated with Benzo(a)Pyrene (BaP, 11.5 μg/g MPs) or benzophenone-3 (BP3, 66 ng/g MPs). Several indicators of health status such as survival, growth, behaviour, energy metabolism, and histopathology were studied. Sole individuals fed ragworms exposed to eMPs or PVC MPs displayed a change in behaviour (place preference between black/white background). Seine Estuary eMPs lead to an increase in body colour chroma for the highest concentration and behaviour was modified with an increase in time spent on white bottom and transition number for the highest concentration when distance moved increased only at the lowest concentration. Sole exposed to BaP-PVC-MPs displayed the lowest time spent on white background compared to control and BP3-PVC-MPs group. Soles exposed to BP3-PVC MPs displayed a significant skin colour increase in chroma and a wider combination of value/chroma reflecting more diverse skin colours. Finally, lipid content in muscle and DNA damage were significantly higher in BP3-MPs. Although the exact mechanisms underpinning such changes are largely unknown, these observations are indicative of physiological stress which may have a significant impact on survival by increasing predation risks for fish juveniles, hence the ecosystem health and calls for further trophic transfer experimental research
Vingtième anniversaire de la loi n° 2005-102 du 11 février 2005 : « Cuivis potest accidere, quod cuiquam potest », mais encore ?
No full textInternational audienceTwenty years after the promulgation of Law 2005-102 of 11 February 2005 on equal rights and opportunities, participation and citizenship for people with disabilities, it would appear that its application has been mixed, to say the least. While a number of institutional provisions have been implemented, a significant proportion of its requirements have still not been met, particularly in terms of accessibility and school inclusion. This article, in the form of an editorial, takes advantage of this twentieth anniversary to take stock of the application of the law, identify the current state of public policy on disability and suggest ways forward.Veinte años después de la promulgación de la Ley 2005-102, de 11 de febrero de 2005, de igualdad de derechos y oportunidades, participación y ciudadanía de las personas con discapacidad, parece que su aplicación ha sido, cuando menos, desigual. Si bien se han puesto en práctica algunas disposiciones institucionales, una parte importante de sus exigencias siguen sin cumplirse, sobre todo en materia de accesibilidad e inclusión escolar. Este artículo, en forma de editorial, aprovecha este vigésimo aniversario para hacer balance de la aplicación de la ley, identificar el estado actual de las políticas públicas en materia de discapacidad y sugerir pistas para el futuro.Vingt ans après la promulgation de la loi n° 2005–102 du 11 février 2005 pour l'égalité des droits et des chances, la participation et la citoyenneté des personnes handicapées, il apparaît que son application est pour le moins contrastée. Si un certain nombre de dispositions institutionnelles a bien été mis en oeuvre, pour autant une part importante de ses prescription n'est toujours pas suivi d'effets, notamment en matière d'accessibilité ou encore d'inclusion scolaire. Cet article, sous forme d'éditorial, profite de ce vingtième anniversaire pour faire le bilan de l'application de la loi, identifier l'état actuel de la politique publique en matière de handicap et proposer des perspectives d'amélioration
Evaluation of the Potential of Natural Mining By-Products as Constituents of Stabilized Rammed Earth Building Materials
No full textInternational audienceIn this investigation, different natural by-products were used to modify the Particle Size Distribution (PSD) of a soil to evaluate their potential in Stabilized Rammed Earth (SRE) building. Three different mixes were manufactured: (i) a mix composed entirely of a clayey soil, (ii) a mix consisting of mining by-products and clayey soil and (iii) a mix entirely based on mining by-products. Unstabilized and stabilized samples of the mixes were manufactured using two cement dosages (2.5% and 5%), and the samples were tested for Unconfined Compressive Strength (UCS), soaked UCS, and wetting and drying tests. Mining by-products demonstrated significant potential in SRE building, as their addition to the clayey soil resulted in higher UCS values compared to the UCS obtained from clayey soil alone. Unstabilized samples lost their integrity during exposure to water. The inclusion of mining by-products also showed potential as, although the mixes did not fully meet the requirements for soaked UCS and the wetting and drying tests, the mix containing both mining by-products and clayey soil retained its integrity in water, unlike the samples composed solely of clayey soil. M3C5 successfully met the requirements for soaked UCS and the wetting and drying tests, further highlighting the great potential of mining by-products in SRE building
Deciphering Degassing Mechanisms of He and H2 at the Sedimentary Basin‐Basement Interface by Surface Geophysics and Gas Geochemistry
No full textInternational audienceWith the increasing importance of the carbon footprint of transport, new sources, closer to consumers, of and He are explored. Within this context, we present a combined near‐surface geophysical imaging, soil gas sampling, and bubbling well gas sampling approach to study fluid and gas pathways near a fault system in the Morvan massif, part of the French Massif Central, in the south‐east of the Paris Basin. Electrical resistivity and seismic refraction tomography profiles allowed identifying a fault network. The co‐located soil gas sampling shows a He hot‐spot clearly linked to a section of one fault, suggesting a preferential pathway via water advection. Very high He concentrations, are also measured in ‐dominated free gas from two bubbling wells very close to the soil He hot‐spot. Evidence for a water reservoir with high ‐He gas bubbles in the very shallow basement‐sediment cover interface is obtained through our geophysical data. In contrast, spreads more widely, pointing to biological production and consumption coupled to soil aeration, as well as a possible geological seep with diffusion processes controlled by clay/marls. The very distinct spatial variability observed for He and results from these different transport processes. A simple geochemical model is proposed to explain the geochemical signature of bubble gas, rich in and He, through exsolution of air dissolved at recharge, where radiogenic He originates from the granitic basement
Face à la métropolisation : repenser l’enseignement de la pratique du projet au prisme des transitions
No full textInternational audienc
Carbon and hydrogen isotope fractionation during aqueous diffusion of benzene
No full textInternational audienceCompound-specific isotope analysis is widely used for evaluating the degradation of organic compounds in aquifers. We investigated the potential of aqueous diffusion of benzene under aquifer conditions (310 K, 70 bars) to cause significant isotope fractionation that might bias the estimates of biodegradation. Diffusion coefficients were computed using external fieldnon-equilibrium molecular dynamics simulations for benzene isotopologues with fictive masses to investigate the influence of molecular mass on aqueous diffusion. Our findings reveal variable power-law relations between molecular masses and diffusion coefficients depending on mass distribution, none of them being consistent with the kinetic theory often used to address isotopic effects on solute diffusion, even in dense solvents. Fictive isotopologues with mass substitutions not affecting the symmetry of the molecule consistently align with a power-law exponent β a = 0.038. In contrast, mass substitutions on a single atom within the benzene molecule (either hydrogen or carbon) result in a smaller mass dependency with βs = 0.021. This result implies that isotopically-labelled molecules such as perdeuterated benzene might not behave similarly to naturally-occurring mono-substituted molecules, an observation that is of importance for the use of these compounds in laboratory experiments. The resulting fractionation factor for mono-substituted benzene isotopologues is -0.3 ‰, and hardly contributes to the variations in benzene isotope composition under aquifer conditions, which validates the use of isotope ratios for evaluating biodegradation of organic compounds in aquifers
Mini-review on the evaluation of thermodynamic parameters for surfactants adsorption onto rock reservoirs: cEOR applications
No full textInternational audienceUnderstanding thermodynamic parameters such as Gibbs free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) is crucial for characterizing surfactant adsorption mechanisms in chemical enhanced oil recovery (cEOR). This paper synthesizes recent studies on the thermodynamics of surfactant adsorption onto various reservoirs rock types, with a focus on quantitative and qualitative parameters critical to optimizing cEOR processes. Generally, surfactant adsorption is exothermic; for example, adsorption of sodium dodecyl sulfate and cetyltrimethylammonium bromide on sandstone and carbonate rocks yields ΔH° values between − 8 and − 20 kJ mol−1 under typical reservoirs conditions. However, adsorption behaviors are influenced by factors such as surfactant type, rock mineralogy, salinity, and temperature, with occasional endothermic interactions observed in high-temperature reservoirs or with specific non-ionic surfactants. A positive linear correlation between ΔH° and ΔS° is commonly observed, indicating that increases in exothermic enthalpy (more negative ΔH°) are associated with increases in entropy (positive ΔS°), suggesting that adsorption processes that promote greater interfacial disorder are energetically favorable. This review not only consolidates key thermodynamic concepts but also provides a comparative analysis of thermodynamic parameters across different rock-surfactant systems, identifying trends and gaps in the literature. By offering insights into the specific conditions that enhance surfactant performance, this study establishes a thermodynamic framework to guide surfactant selection and optimization in cEOR. These contributions aim to deepen understanding of adsorption behavior and inform more effective, tailored cEOR strategie
Stochastic modelling of non-stationary and dependent weather extremes for structural reliability analysis in the changing climate
No full textInternational audienceIn recent times, the safety of infrastructure systems has been challenged by the increasing severity of extreme weather events caused by the effects of climate change. This trend is expected to continue, as shown by the simulations of future climate conditions under high-emission scenarios. The paper presents a general stochastic process, known as the Linear Extension of the Yule Process (LEYP), to model the non-stationary frequency and intensity of extremes. The LEYP model overcomes a major limitation of the classical Poisson process by including the statistical dependence among extreme events.The paper presents a probabilistic framework for non-stationary structural reliability analysis, which includes new results for the return period, waiting time for the next event, correlation coefficient, and the distribution of the maximum load in a given time interval. The examples provided in the paper demonstrate that even a modest degree of dependence can significantly reduce the interval between events and increase the probability of failure with time. Furthermore, the paper illustrates the non-stationary modelling of future precipitation data, as simulated by the Canadian Earth Systems Model (CanESM5). The results of this study are expected to be useful for revising current "stationary" design codes and ensuring structural safety in the changing climate.</p
Simulations des distributions gamma multivariées et des distributions gamma multifacteurs
No full textInternational audienceThis article provides a general expression for infinitely divisible multivariate gamma distributions defined by their Laplace transforms, as well as the conditional Laplace transform of infinitely divisible multivariate gamma distributions.We give algorithms for simulating infinitely divisible gamma distributions and infinitely divisible multifactor gamma distributions in dimension 2,3,4 and for all dimensions greater than 2 in the Markovian case. We give examples of simulations in dimension 2,3,4 and in dimension 5 in the Markovian case.Cet article fournit une expression générale pour les distributions gamma multivariées infiniment divisibles définies par leur transformée de Laplace infiniment divisibles définies par leurs transformées de Laplace, ainsi que la transformée de Laplace conditionnelle des distributions gamma multivariées infiniment divisibles. Nous donnons des algorithmes pour simuler les distributions gamma infiniment divisibles et les distributions gamma multifacteurs indéfiniment divisibles en dimension 2,3,4 et pour toutes les dimensions supérieures à 2 dans le cas markovien. Nous donnons des exemples de simulations en dimension 2,3,4 et en dimension 5 dans le cas markovien