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Non-marine Ostracoda (Crustacea) collected from the Camargue, southern France, with four species new to France
No full textInternational audienceWe report on the collection of 21 non-marine Ostracoda (Crustacea) species, mainly in July 2022, in the Rhône delta (Grande Camargue). The material comprises nine species new to the Camargue region (Grand delta du Rhône), of which four are new to France. These four are considered exotic in origin, and we suggest that they have been passively introduced in the Camargue during the second half of the 20 th century: Bradleytriebella spinulosa (Akatova, 1958) nov. comb., Candonocypris novaezelandiae (Baird, 1843), Cypris granulata Daday, 1898, and Ilyodromus viridulus (Brady, 1886). Notes on these four species, and two previously recorded exotic species, i.e. Bradleycypris vittata (Sars, 1903) and Strandesia reticulata (Daday, 1898) from the Camargue are presented. Scanning electron micrographs of the carapaces and/or valves of all the species recorded are given. A checklist of the 44 non-marine ostracod species recorded from the Grand delta du Rhône is presented. A new taxonomic combination is provided: Bradleytriebella spinulosa (Akatova, 1958) nov. comb
Historical bias in palaeontological collections: Stylophora (Echinodermata) as a case study
No full textInternational audienceScientific colonialism (sensu Galtung, 1967) has grown in interest for the last decades in all scientific disciplines, including Palaeontology. In particular, Raja et al. (2022) showed that the Paleobiology Database (PBDB) was mostly based on research investigations from and/or in higher-income countries (i.e., the Global North). This scientific practice, better known as “parachute science”, often implies a transfer of material from their country of origin (in the Global South) to another country of collection (in the Global North). We show that this global pattern can also be observed at a lower taxonomic scale by focusing on Stylophora, an extinct class of echinoderms. Based on a database gathering the 129 stylophoran holotypes including information of their year of description, country of origin, country of collection and author affiliation, we show comparable results to those of Raja et al. (2022). Indeed, 85% of stylophoran species originated from the Global North. Transferred material represents 17% of the holotypes and none of the corresponding publications included local collaboration. We detail the most highlighting example of parachute science, the duo Morocco-France, to understand the consequences of the colonial history between these two countries in the scientific practice of French researchers in Morocco, as well as the solution brought by Moroccan researchers and government. These results, while not surprising, mean that scientific colonialism is indeed observed not only in global databases, but also in our daily work. Researchers from the Global North then can act to decolonize their problematic practice to rebalance knowledge producing to build a true Global Research Community
Design for Strong sustainability (DfSoSy) : une méthodologie pour une approche de circularité forte ?
No full textInternational audienceDepuis le rapport de la Commission mondiale sur l’environnement et ledéveloppement en 1987, deux interprétations du développement durable ont émergé.[1] distingue ainsi la soutenabilité faible et la soutenabilité forte. Selon [2] lasoutenabilité faible repose sur une vision du statu quo, considérant que la croissanceéconomique, l’équité sociale et la préservation écologique peuvent coexister sansconflits majeurs. À l’inverse, une soutenabilité forte implique le respect des limitesplanétaires [3] et intègre pleinement les questions de justice sociale et d’équité [4]
Coordination environments of Pt single-atom catalysts from NMR signatures
No full textInternational audienceSupported metal catalysts that integrate atomically dispersed species with controlled structures lie at the forefront of catalytic materials design, offering exceptional control over reactivity and high metal utilization, approaching the precision of molecular systems. However, accurately resolving the local metal coordination environments remains challenging, hindering the advancement of structure–activity relationships needed to optimize their design for diverse applications. Although electron microscopy reveals atomic dispersion, conventional spectroscopic methods used in heterogeneous catalysis only provide average structural information. Here we demonstrate that 195Pt solid-state nuclear magnetic resonance (NMR) spectroscopy is a powerful tool for characterizing atomically dispersed Pt sites on various supports, so called single-atom catalysts (SACs). Monte Carlo simulations allow the conversion of NMR spectra into SAC signatures that describe coordination environments with molecular precision, enabling quantitative assessment of Pt-site distribution and homogeneity. This methodology can track the influence of synthetic parameters, uncovering the impact of specific steps and support types, and can also monitor changes upon reaction. It offers critical insights for the reproducible developmentof SACs with targeted structures. Beyond SACs, this approach lays the foundation for studying more complex architectures, such as dual-atom or single-cluster catalysts, containing various NMR-active metals
Secular brightness curves of 272 comets
No full textInternational audienceAims . We investigate the brightening behavior of long-period comets as a function of dynamical age, defined by the original reciprocal semimajor axis, 1/ a 0 . Our goal is to test long-standing claims about comet behavior using a large number of available measurements. Methods . We used a large set of photometric observations to compute and analyze global and local brightening curves for 272 long-period comets. We fit the observed magnitudes with a linear model in log heliocentric distance, from which we derived brightening parameters for each comet. We categorized the sample into dynamically new, intermediate, and old comets, and we compared their brightening behavior. We also examined the relationships between dynamical age and other orbital and physical parameters. Results . Dynamically new comets are seen to brighten more slowly than old comets, particularly within 3 au from the Sun. The brightening rate of new comets appears to vary with heliocentric distance. New comets are intrinsically brighter than old comets and exhibit a tighter correlation between brightening parameters
Ordonnancement de tâches avec un nombre variable de processeurs
No full textEven though it is usually assumed that data centers can always operate at maximum capacity, there have been recent scenarios where the amount of electricity that can be used by data centers evolve over time. Hence, the number of available processors is not a constant anymore. In this work, we assume that jobs can be checkpointed before a resource change. Indeed, in the scenarios that we consider, the resource provider warns the user before a change in the number of processors. It is thus possible to anticipate and take checkpoints before the change happens, such that no work is ever lost. The goal is then to maximize the goodput and/or the minimum yield of jobs within the next section (time between two changes in the number of processors). We model the problem and design greedy solutions and sophisticated dynamic programming algorithms with some optimality results for jobs of infinite duration, and adapt the algorithms to finite jobs. A comprehensive set of simulations, building on real-life job sets, demonstrates the performance of the proposed algorithms. Most algorithms achieve a useful platform utilization (goodput) of over 95%. With infinite jobs, the algorithms also keep fairness by having a relative minimum yield above 0.8, meaning that each job gets a good access to the platform (80% of the time that it would have had if each job had its perfect share of the platform). For finite jobs, the minimum yield can be low since very short new jobs may have to wait until the beginning of the next section to start (and finish), significantly impacting their yield. However, for 75% of the jobs within each workload, the yield ratio between these jobs is at most at a factor two, hence demonstrating the fairness of the proposed algorithms.Même si l'on part généralement du principe que les centres de calcul peuvent toujours fonctionner à leur capacité maximale, des scénarios récents ont montré que la quantité d'électricité pouvant être utilisée par les centres de calcul évolue au fil du temps. Par conséquent, le nombre de processeurs disponibles n'est plus une constante. Dans ce travail, nous supposons que les tâches peuvent être sauvegardées avant un changement de ressources. En effet, dans les scénarios que nous considérons, le fournisseur de ressources avertit l'utilisateur avant un changement du nombre de processeurs. Il est donc possible d'anticiper et d'effectuer une sauvegarde avant que le changement ne se produise, de sorte qu'aucun travail ne soit jamais perdu. L'objectif est alors de maximiser l'utilisation de la plateforme (goodput) et/ou l'avancement minimum (yield) des tâches au cours de la section suivante (temps entre deux changements du nombre de processeurs). Nous modélisons le problème et concevons des solutions gloutonnes et des algorithmes de programmation dynamique sophistiqués avec certains résultats d'optimalité pour les tâches de durée infinie, puis nous adaptons ces algorithmes aux tâches de durée finie. Un ensemble de simulations utilisant des tâches réalistes démontre les performances des algorithmes proposés. En effet, la plupart des algorithmes atteignent une utilisation utile de la plateforme (goodput) supérieure à 95%. Avec des tâches infinies, les algorithmes maintiennent également l'équité en ayant un avancement minimum (yield) relatif supérieur à 0.8, ce qui signifie que chaque tâche bénéficie d'un bon accès à la plateforme (80% du temps dont elle aurait disposé si chaque tâche avait eu sa fraction parfaite de la plateforme). Pour les tâches finies, l'avancement minimum peut être faible, car les nouvelles tâches très courtes peuvent devoir attendre le début de la section suivante pour démarrer (et se terminer), ce qui a un impact significatif sur leur avancement. Cependant, pour 75% des tâches, le rapport de l'avancement entre ces tâches est au maximum de deux, ce qui montre l'équité des algorithmes proposés
La régulation du mécanisme de la réparation de l'ADN par recombinaison homologue par la transcription
No full textHomologous recombination (HR) is a template-dependent mechanism for the repair of DNA double-strand breaks. Unlike replication and transcription, the possible conflicts between transcription and HR have not been thoroughly investigated. Here, we addressed whether transcription carried out by RNA polymerase II interferes with D-loop metabolism and how this interference promotes HR fidelity. Our work shows that transcription of the “donor” molecule causes D-loop disruption and inhibits downstream repair steps. This inhibition occurs acutely and is independent of endogenous transcription factors, RNA/DNA hybrids, or the RNA produced in trans. Instead, the acute disruption of D-loops upon transcription activation is dependent on transcription orientation, suggesting a direct effect of the RNA Pol II motor in disrupting D-loops in cis. Depending on promoter strength, transcription can be the major D-loop disruption pathway, acting independently of previously characterized trans-D-loop disruption activities mediated by Sgs1-Top3-Rmi1BLM-TOPO3-RMI1/2, Mph1FANCM, and Srs2. This cis-acting layer of HR regulation inhibits the formation of chromosomal rearrangements induced upon endonucleolytic processing of multi-invasion DNA joint molecules. Consequently, transcription mediated by RNA Polymerase II is a novel cis-acting negative regulator of HR at the D-loop level that unevenly protects the genome against repeat-mediated chromosomal rearrangements.La régulation des processus dépendants de l'ADN en compétition dans les cellules, reste mal défini. La recombinaison homologue (RH) est un mécanisme de haute-fidélité pour la réparation des cassures double-brin de l'ADN (DSB) qui utilise une molécule d'ADN double brin homologue intacte comme modèle de réparation, par la formation d'une molécule d'ADN conjointe appelée D-loop. Ici, nous explorons si la transcription, un processus moléculaire compétiteur dépendant de l'ADN, réalisé par l'ARN polymérase II (PolII), pourrait interférer avec la recombinaison. En utilisant de nouvelles méthodes moléculaires pour détecter l'intermédiaire, D-loop, nous montrons que la transcription de la molécule homologue « le donneur» par l'ARN pol II déstabilise les structures d'ADN conjointes D-loop et inhibe les étapes de réparation en aval. Cette inhibition est importante et indépendante des facteurs de transcription endogènes, des hybrides ARN: ADN, ou de l'ARN produit en trans, suggérant un effet direct du moteur de l'ARN Pol II dans la perturbation des D-loops en cis. La transcription peut être la principale voie de déstabilisation de la D-loop, qui agit indépendamment des activités de déstabilisation en trans, précédemment caractérisées, médiées par Sgs1-Top3-Rmi1(BLM-TOPO3-RMI1/2), Mph1(FANCM), Srs2, Rdh54(RAD54B). Enfin, la transcription du donneur inhibe la formation de réarrangements chromosomiques induits par la résolution endonucléolytique des molécules d'ADN conjointes à la multi-invasion. Par conséquent, la transcription médiée par l'ARN pol II est un régulateur négatif en cis de la RH au niveau de la D-loop qui protège de manière efficace le génome contre les réarrangements chromosomiques médiés par les séquences répétées
Nuclear auxin signalling induces autophagy for developmental reprogramming
No full textThe phytohormone auxin is a central regulator of plant growth and development, traditionally known for mediating transcriptional reprogramming through the canonical TIR1/AFB-Aux/IAA signalling pathway. In this study, we reveal that auxin rapidly induces macroautophagy, a catabolic process critical for the removal and recycling of superfluous macromolecules. We demonstrate that natural auxin (IAA) triggers autophagy at physiological concentrations. Genetic and pharmacological analyses show that TIR1/AFB receptors and their adenylate cyclase activity are indispensable for autophagy induction. Furthermore, auxin-induced autophagy depends on transcription, highlighting its integration with the broader gene regulatory networks. Functionally, we show that auxin-induced autophagy is required for efficient developmental reprogramming and organogenesis in both root and shoots. Autophagy is induced at places of local auxin maxima and autophagy-deficient mutants exhibit delayed differentiation and retarded organ primordia progression at the meristematic zones. Together, our findings uncover a dual role for auxin in coordinating gene expression and autophagic clearance, thereby facilitating rapid and effective developmental transitions
Organelle-Specific Thiochromenocarbazole Imide Derivative as a Heavy-Atom-Free Type I Photosensitizer for Biomolecule-Triggered Image-Guided Photodynamic Therapy
No full textInternational audienceModern photodynamic therapy (PDT) demands next-generation photosensitizers (PSs) that overcome heavy-atom dependency and enhance efficacy beyond traditional, highly oxygen-dependent type II mechanisms. We introduce herein TCI-NH, as a thiochromenocarbazole imide derivative designed for type I photodynamic action. Upon light activation, TCI-NH efficiently favors superoxide (O 2•-) and PS-centered radical formation instead of singlet oxygen ( 1 O 2 ) generation. Its high luminescence efficiency and selective localization in both the endoplasmic reticulum and mitochondria enable precise, image-guided PDT. Notably, interactions with biomolecules, such as serum albumin or DNA, enhance TCI-NH's emission by up to 40-fold and amplify radical generation by up to 5-fold. With negligible dark toxicity, this results in ∼120 nM photocytotoxicity along with an impressive phototherapeutic index exceeding 200. Real-time live-cell imaging revealed rapid, light-triggered cytotoxicity characterized by apoptotic body formation and extensive cellular damage. With its small size, heavy-atom-free structure, exceptional, organelle specificity, and therapeutic efficacy, TCI-NH sets a new benchmark for anticancer type I PDT.</p
Table ronde inter-active. Penser le travail depuis la danse
No full textInternational audienceInitiée par des membres ergonomes de l’Atelier de recherche-création Transitions Sensibles(https://www.imera.fr/transitions-sensibles/), l’objectif de cette table ronde est de proposer une discussion pour "penser le travail depuis la danse" (Baudin, 2024). Notre intention et notre invitation à la communauté des ergonomes est d’ouvrir et d’interroger les conceptions et approches de l’activité de travail depuis l’expérience incarnée, située et expressive des danses au travail, des corps en mouvement et en gestes. En ce sens, la pensée du corps en danse,comme corps en geste, est une pensée féconde pour l’approche ergonomique