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Cobalt induces the set-up of new structural networks in river biofilms: Impairment of autotrophic-heterotrophic coupling
No full textInternational audienceBiofilms are integral to the biogeochemical cycles of aquatic ecosystems, primarily through complex interactions among microorganism that mediate the transformation and movement of key elements. In a previous study, we reported that Cyanobacteria within biofilms grown in outdoor mesocosms exhibited sensitivity to cobalt (Co) when exposed to increasing Co concentrations (background concentrations, 0.1, 0.5, and 1 μM). Under exposure to Co, biofilms were found to adopt alternative carbon fixation pathways via non-photosynthetic prokaryotes, suggesting a disruption in phototrophic activity and raising questions about broader autotroph–heterotroph interactions that drive biofilm functions. In the present study, we extended this investigation to assess the impact of Co on microeukaryotes (primarily microalgae) and their interactions with prokaryotes, thereby encompassing the entire biofilm community. Eukaryotic abundance and diversity were quantified using qPCR and DNA metabarcoding, while microbial interactions were inferred through co-occurrence network analysis based on operational taxonomic units (OTUs). Our findings indicate that Co exposure significantly altered the composition of the microalgal and meiofaunal communities, with Bacillariophycea exhibiting pronounced sensitivity. At 1 μM Co, microbial networks were characterized by reduced OTU richness and fewer interactions, yet displayed stronger structural centrality around a limited number of taxa. Notably, in control conditions, 40 % of keystone taxa were affiliated with microalgae, whereas at 1 μM Co, keystone taxa were predominantly prokaryotic. These results indicate that Co disrupts autotroph-heterotroph coupling, driving a shift toward prokaryotic dominance in microbial interactions. The study highlights adaptive strategies employed by biofilms to mitigate metal-induced stress and maintain functional integrity in contaminated environments
Sur les conditions de ‘littérarisation’ du journal personnel en France : notes pour une poétique
No full textInternational audiencePour reprendre une formule de Roland Barthes, le journal intime ou personnel demeure un « défi à la littérature » : son statut littéraire n’est ni manifeste ni stable. Je pose l’hypothèse que cette ‘littérarisation’ incomplète s’explique par l’origine du genre et le maintien d’une pratique ordinaire, par ses caractères propres, et aujourd’hui par une transformation de « l’idée de littérature ». Après avoir rappelé comment le genre s’est partiellement intégré à la littérature au long des XIXe et XXe siècles, je m’attache à identifier ce qui limite encore sa pleine reconnaissance aujourd’hui et ce que cela dit de la littérature aujourd’hui
Assessment of the Association Constant of the CO 2 @CB[6] Complex Combining 1 H and 13 C NMR Spectroscopic Titrations
No full textInternational audienceA methodology for assessing the association constants of a molecular host binding a 13 C‐enriched gaseous guest, that is, 13 CO 2 , using NMR spectroscopic titrations is described. The method relies on injecting the gaseous guest into the headspace of a gas‐tight NMR tube filled with the host's solution. The fraction of the gas dissolved in the liquid solution is quantified via 13 C NMR spectroscopy using the Electronic Reference To Access In Vivo Concentrations technique without requiring assumptions based on Henry's law. By subsequently recording the 1 H NMR spectrum of the solution mixture, the relationship between the chemical shift changes experienced by the proton signals of the host and the precise concentration of the added gaseous guest can be established. Repeating the process over a range of incremental gas concentrations allows for generating the binding isotherm curve. The nonlinear computer fit of the data to a suitable theoretical binding model returns the values of the association constant and the complexation‐induced shift for the protons in the complex. The method is applied to the assessment of the association constant values of the complexes formed from the interaction of 13 CO 2 with two macrocyclic receptors
Figurer l'indicible: la fonction du récit de cas chez Ambroise Paré
No full textInternational audienceLes récits de cas qui émaillent les Œuvres d’Ambroise Paré ne viennent pas seulement rendre son enseignement plus concret ; leur fonction ne se borne pas non plus à asseoir sa réputation de chirurgien ou à légitimer son statut d’auteur. Ces histoires installent la figure du « chirurgien rationel », maitrisant un savoir théorique qu’il applique ou conteste, selon son jugement, fort aussi de sa longue expérience clinique. Affranchi de la tutelle des médecins, il se montre capable de prendre en charge seul ses patients, depuis le tout premier diagnostic jusqu’à la guérison. A travers ces « histoires mémorables », Réorganisant la hiérarchie des corporations, Paré modifie également la déontologie concernant les cas désespérés ou les mourants. Somme toute, loin d’être des compléments dispensables du texte théorique, des « ornements » du discours médical, ils en constituent la part la plus audacieuse, la plus subversive
The Evolution of the IR and Raman Spectra When the Symmetry Reduces-The Case of the LaCoO 3 Perovskite
No full textInternational audienceThe IR and Raman spectra of the LaCoO3 perovskite (the formal occupancy on Co is d 6 , low spin, t2g 6 ) are computed by imposing space groups (SG) of decreasing symmetry, from the cubic (SG Pm-3m, N. 221, and Fm-3m, N. 225), to the tetragonal (SG 140), rhombohedral (SG 167) and orthorhombic (SG 62) ones. The total energy differences between these structures, computed at the quantum mechanical level by using an all electron Gaussian type basis set and the full range hybrid B3LYP functional, is extremely small: 0.2 mEh between SG 167 and SG 62, 1.2 mEh between SG 140 and SG 62, and 4.5 mEh between the most stable structure and the cubic, ideal aristotype. These minor differences indicate that the experimentally proposed SG might be one of the (many) possible alternatives. The IR and Raman spectra are very rarely used for the identification of the symmetry of the perovskites at different temperatures. Here we investigate the evolution of the two spectra (IR and Raman) through the various competing space groups, exploring the possibility that they might be used for the identification of the low temperature structure (SG and position of the atoms) of the investigated compounds, and of perovskites in particular
Le segretain moine 1 - Édité d'après le ms. BnF fr. 2168
No full textLe segretain moine 1 - Édité d'après le ms. BnF fr. 216
Suppléer le médecin ou l'évincer? Le statut de chirurgien dans le "Livre de la peste" et dans les "Œuvres" d'Ambroise Paré
No full textInternational audienceEn 1564, alors que la peste sévit dans la région lyonnaise où séjourne la cour, Catherine de Médicis demande à Ambroise Paré de rédiger un traité sur la maladie. Fort de cette commande royale, le chirurgien outrepasse les attributions de sa corporation en dissertant, par exemple, sur les causes de la maladie ou sur les fièvres qu’elle provoque. Il installe dans son "Traicté de la Peste" publié en 1568 la figure d’un "docte chirurgien" qui ne sera plus un simple exécutant aux ordres du médecin. Le contexte de l’épidémie, que fuient de nombreux médecins, favorise cette émancipation et confère même aux chirurgiens une mission religieuse : leur dévouement ne peut qu’apaiser la colère divine, première cause du fléau. Paré réorganise ainsi la hiérarchie des corporations médicales, en se fondant sur les nouvelles voies de diffusion du savoir, désormais à la portée de son "chirurgien rationnel", ainsi que sur un renouveau de la déontologie
Time-course of mRNA abundance of appetite-regulatory genes in the brain of rainbow trout fed a plant-based diet from the first feeding
No full textInternational audienceThe early developmental stages of fish are critical for improving feeding strategies and growth performance. Understanding feeding-regulatory mechanisms from the earliest stages of development is crucial, especially in the context of aquaculture, where early nutrition has a significant impact on feeding behaviour, growth and survival. This is particularly relevant in carnivorous species, such as rainbow trout (Oncorhynchus mykiss), where the complete replacement of fishmeal and fish oil with plant-based ingredients has negative effects on growth performance and early stage survival. This study investigates the time-course of mRNA abundance of genes encoding key appetite-regulatory neuropeptides and integrative signalling pathways from first feeding to 100 days post-feeding with either a commercial-like diet containing fishmeal and fish oil or a plant-based diet devoid of these marine-derived ingredients. Results showed that an initial diet based on plants does not notably affect the levels of mRNA for appetite-regulating neuropeptides in the brain of rainbow trout alevins. However, the plant-based diet induced slightly distinct patterns in gene mRNA abundance after the first meal, which may underpin reduced feed intake and growth performance. Some key appetite-regulatory neuropeptides, such as neuropeptide Y (npy) and cocaine-and amphetamine-regulated transcript (cartpt), exhibited progressive higher levels in the brain over time, while agouti-related protein 1 (agrp1) and pro-opiomelanocortin a1 (pomca1) levels decreased following initial feeding. Moreover, the expression of key integrative signalling components, including AMP-activated kinase α2 (pkraa2), mechanistic target of rapamycin (mtor), cAMP response-element binding protein 1 (creb1), and forkhead box O1 (foxo1), increased throughout growth, but their abundance was modulated differently by the dietary treatments. This study underscores the importance of understanding neuroendocrine responses to dietary formulations for optimizing aquafeeds and enhancing sustainability in aquaculture
Journées Scientifiques du Département Sciences de la Vie et Santé - AgroParisTech
No full textThe "AgroParisTech Life Science and Health division scientific symposium " took place on April 25 and 26, 2024, on the AgroParistech's Palaiseau campus. This event aimed to present, share, and discuss the current research conducted by the department’s scientific teams. It provided an opportunity for everyone to explore ongoing scientific work in SVS, discuss its connections to current challenges in life sciences and agronomy, and see how this research enriches the courses offered at the institution.Les "Premières Journées Scientifiques du Département des Sciences de la Vie et de la Santé" on eu lieu les 25 et 26 avril 2024 sur le campus de Palaiseau. Cet événement visait à présenter, partager et discuter des recherches actuellement menées par les équipes scientifiques du département. Afin de permettre à tous et toutes de découvrir les travaux en cours des scientifiques de SVS, à discuter des liens avec les enjeux actuels en sciences du vivant et en agronomie, et à voir comment ces recherches enrichissent les enseignements dispensés dans l’établissement
