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Neurological signs identified by Ai related to stroke patient recanalization
No full textInternational audienceBackground and Aims: Thrombus dimensions are critical factors influencing early recanalisation following thrombolysis in stroke patients and the Susceptibility Vessel Sign (SVS), a ferromagnetic artefact, reflects the composition of the thrombus [1] (iron content and therefore red blood cell content). However, their manual estimation becomes challenging for distal occlusions, those located beyond the proximal M2 segment of the middle cerebral artery. We present a novel artificial intelligent (AI) tool that segments distal thrombi from MRI images, automatically calculates thrombus dimensions and investigates their relationship with the AOL recanalisation status one hour after treatment. Successful recanalisation is defined as AOL ⩾2b.Methods: Our deep learning model combines key imaging modalities: Diffusion Weighted Imaging (DWI) which highlights the lesion and Susceptibility weighted Imaging (SWAN) where thrombi are visible. Trained on 300 annotated cases, the model recurrently segments clots. Enabling fully automated analysis, thrombus length is calculated using the maximum Feret diameter (greatest distance between the two parallel planes) and thrombus width is derived from its orthogonal dimension. Additionally, the SVS is computed as the ratio of the thrombi width to the minimum width (per artery).Results: Our model achieves 70% thrombus volume accuracy with a mean error of 1.1±0.8mm between actual and estimated lengths. Statistical analysis reveals that thrombi in non-recanalized patients are significantly longer (t-test, p = 0.001). Moreover, a larger SVS is significantly associated with successful recanalization (p = 0.024).Conclusion: The proposed AI tool offers an automated accurate method for thrombus segmentation and dimension estimation that can offer valuable insights for predicting recanalisation success.Disclosure of interest: All authors: nothing to disclos
The late rise of sky-island vegetation in the European Alps
No full textInternational audienceOur understanding of the emergence of mountain floras rests on our ability to infer how orogeny, landscape dynamics and climate change altered their evolutionary trajectories. Here, we reconstruct the assembly of the diverse sky-island flora of the European Alps and test the impact of key geo-climatic events. We use a dated 5,231-species phylogeny, including 96% of the sky-island flora. The assembly of this flora occurred through the colonisation of over a thousand distinct lineages, of which 46% speciated from their lowland ancestor and 6% underwent in situ cladogenesis. The young ages of extant sky-islands lineages show that their accumulation was decoupled from ancient geo-climatic events, but accelerated throughout the Plio-Pleistocene. The sky-island vegetation therefore assembled through recent lineage turnover, which was triggered, rather than impeded, by Pleistocene glacial intensification. This perspective challenges previous assumptions and highlights the complex interplay of geo-climatic factors in shaping the intricate tapestry of alpine floras
Ideas and perspectives: Using meta-omics to unravel biogeochemical changes from cell to planetary scales
No full textIncreased human impacts on Earth systems are radically altering biogeochemical cycles. While long-term environmental observatories and Earth System Models (ESMs) provide valuable insights into the mechanisms of nutrient dynamics, their performance is limited at the fine spatial scales controlled by the functional diversity of plant and microbial communities. This gap in our understanding concerning the roles of microbial diversity and plant-microbial interactions in decomposition and nutrient dynamics extends across many global ecosystems. Recent advances in meta-omics technologies, including metagenomics, metatranscriptomics, metaproteomics, and metabolomics, offer a wide array of tools for assessing metabolic to genetic to evolutionary drivers of ecosystem functioning. Here, we explore the integration of meta-omics with traditional ecological approaches to examine responses to global environmental changes. We present case studies from diverse environments—soils, aquatic systems, clouds, and paleoarchives—demonstrating how meta-omics can unravel the roles of microbial diversity, metabolic pathways, and trait distributions critical to understanding greenhouse gas fluxes, nutrient cycling, and biogeochemistry. Although meta-omics is still beset with challenges including data heterogeneity arising from wide-ranging methods, omics-derived traits, kinetic parameters, and machine learning tools can be used to enhance ESM predictive capability. For example, emerging applications of meta-omics to ancient environmental DNA are extending our capacity to link historical patterns with future projections, offering a long-term perspective on ecosystem dynamics. This review highlights the potential of integrating omics with experimental manipulations alongside existing monitoring and modelling efforts to refine predictions of ecosystem responses to natural and anthropogenic-driven environmental changes. Because omics approaches cross a range of scientific domains, they could be used to foster collaboration and even integration within existing models, thus laying the foundation for informed conservation and ecosystem management strategies from local to global scales
Ribonucléases et contrôle qualité du transcriptome chloroplastique : prévalence des ARN doubles brins et fonction de la RNase J
No full textChloroplast are descendants of free-living photosynthetic bacteria and maintain a small but essential genome that is fully transcribed. This complex primary transcriptome is then heavily processed by a combination of RNA-binding proteins and ribonucleases to produce the functional RNA population. Among this stringent RNA quality control (QC) mechanism, one poorly understood aspect is the functions of antisense RNAs and more globally double-stranded RNA-related processes. The aim of my PhD was to further explore these RNA QC mechanisms with a particular focus on RNase J and PNPase.I first used full-length transcript sequencing via Nanopore technology to identify the complete set of transcript isoforms present in the chloroplast. This work revealed the coexistence of two RNA degradation pathways, operating in both the 3'-to-5' and 5'-to-3' directions, as well as the widespread presence of antisense RNAs. These antisense RNAs accumulate particularly in PNPase mutants, as this ribonuclease is responsible for 3'-to-5' RNA degradation. Given their potential to form RNA duplexes, I then developed a methodology to identify, characterize, and quantify these RNA-RNA duplexes. My results show a high abundance of such duplexes in the PNPase mutant, where they accumulate as granules at the immediate periphery of the nucleoid.The identification of the 5'-to-3' degradation activity also led me to investigate RNase J, the only known chloroplast RNase capable of degrading RNA in this direction. Using knockout lines complemented with modified versions of the enzyme, I demonstrated its involvement in ribosomal RNA maturation. A key finding is that the GT-1 domain, located at the C-terminal region of the enzyme, binds double-stranded RNAs in vivo and prevents their accumulation by directing the enzyme's catalytic activity. As observed with the PNPase mutant, these double-stranded RNAs also accumulate as granules at the vicinity of the nucleoid. Taken together, my results suggest that a major component of the chloroplast RNA QC may involve the sequestration of RNA molecules and protein factors within functional subcompartments.Le chloroplaste a gardé de son origine endosymbiotique un petit génome dont l'expression est essentielle à la photosynthèse. Ce génome est entièrement transcrit sous forme de polycistrons et les ARN matures et fonctionnels sont ensuite spécifiquement sélectionnés au sein du transcriptome primaire grâce à un contrôle qualité (QC) rigoureux assuré par un ensemble de protéines de liaison à l'ARN et des ribonucléases. Parmi tous ces mécanismes de QC, le rôle des ARN antisens et plus largement des processus impliquant les ARN double brin sont les plus mal connus. Ma thèse a donc pour but d'approfondir la compréhension de ces mécanismes qui façonnent le transcriptome chloroplastique, avec une attention particulière pour la RNase J et la PNPase.J'ai dans un premier temps exploité le séquençage des transcrits pleine longueur grâce à la technologie Nanopore afin d'identifier l'ensemble des isoformes ARN présents dans le chloroplaste. Ce travail a mis en évidence la coexistence de deux mécanismes de dégradation des transcrits 3'-5' et 5'-3' ainsi que la présence abondante d'ARN antisens. Ces ARN s'accumulent particulièrement dans les plantes mutantes pour la PNPase, ribonucléase en charge de la dégradation 3'-5'. Ces ARN ayant la capacité de former des ARN double brins j'ai ensuite développé une méthodologie permettant d'identifier, caractériser et quantifier ces duplex ARN-ARN. Mes résultats montent une grande abondance de ces duplex dans le mutant de la PNPase et qu'ils s'accumulent sous forme de granules dans la périphérie immédiate du nucléoïde.La mise en évidence de l'activité de dégradation 5'-3' m'a également conduit à étudier plus spécifiquement la RNase J, seule RNase capable de dégrader dans cette direction. Grâce à des lignées KO complémentées par des versions modifiées, j'ai pu montrer qu'elle est notamment impliquée dans la maturation des ARN ribosomaux. Un résultat important est la démonstration que le domaine GT-1 situé dans la partie C terminale de l'enzyme lie les ARN double brins in vivo et empêche leur accumulation en guidant l'activité de l'enzyme. Là encore, les ARN double brins identifiés s'accumulent sous forme de granules à la périphérie du nucléoïde. L'ensemble de mes résultats suggèrent qu'une des composantes du QC des ARN chloroplastiques pourrait être la séquestration des acteurs protéiques et ARN dans des sous compartiments fonctionnels
Rejuvenating cooperative governance: the case of an anarchist cooperative
No full textInternational audienceThis paper explores how anarchist principles can rejuvenate cooperative governance. Building on a qualitative case study of a self-managed grocery collective in northern suburb of Paris grounded in anarchist ideals—we examine how the absence of formal structures, reliance on voluntary participation, and commitment to direct democracy challenge conventional cooperative governance models. . Our findings show that anarchist culture fosters autonomy, mutual aid, and horizontal decision-making, offering insights to revitalize cooperative organizations. We argue that hybrid models combining formal and informal governance may strengthen cooperatives' democratic resilience and adaptability in the face of socio-ecological transitions
Human-Inspired Pre-Design Optimization for Humanoid Robots in Dynamic Interaction Tasks
No full textInternational audienceThis study presents a novel pre-design optimization framework for humanoid robots, enabling precise alignment of robotic kinematics with human motion patterns for dynamic tasks. The aim is to reduce prototyping costs and support task-specific designs. Leveraging mechatronics expertise, the framework features an interactive interface for real-time parameter tuning, guided by metrics such as workspace coverage and inverse kinematics (IK) success rate. The predesign tool is applied on a 3-DOF arm, part of an upper-body humanoid robot under development, achieves 100% workspace coverage and an 85.51% IK success rate across four experiments for jabs and hooks. Motion similarity metrics were used to validate human-like performance and smoothness
Development of a Multi-Modal Control Architecture for a Cable-Actuated Ankle Exoskeleton
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Mechanical characterization of femoral popliteal artery: experiments, histology, and model comparison
No full textInternational audiencePeripheral artery disease (PAD) has a high mortality rate and can bring various cardiovascular disease risks, making it an extremely serious type of disease. The porcine femoral popliteal artery (FPA) was selected as research objects to obtain detailed mechanical behavior and arterial structure information of lower limb arteries through biaxial tensile experiments and histopathological analysis. The results showed that the FPA exhibits higher compliance in the longitudinal direction than in the circumferential direction and greater stiffness in the circumferential direction. Histopathological analysis revealed the microstructural changes in the arterial samples after stretching, including partial rupture of elastic fibers, rearrangement and distribution of collagen fibers, and morphological changes in smooth muscle cells (SMCs). The experiment found that tissue damage begins to accumulate when FPA strain exceeds 30%. Both the polyconvex quadratic polynomial SEF (Strain Energy Function) and the exponential SEF effectively captured the mechanical response of these arteries. This study advances the understanding of the mechanical properties and injury mechanisms of the FPA, evaluates the applicability of SEFs, and provides a foundation for future computer modeling research
Un flux de travail guidé par l'IA pour une accélération de l'optimisation d'un système acellulaire de synthèse de protéines
No full textInternational audienceCell-free protein synthesis (CFPS) is a versatile tool for rapid biological prototyping. However, exploring the large number of component combinations is a very time-consuming process. Active learning (AL) is known to reduce the number of experiments required, but is rarely integrated into routine laboratory workflows. To address this, we developed a fully automated Design-Build-Test-Learn (DBTL) pipeline that streamlines this optimization process with an improved AL strategy that selects informative and diverse experimental conditions. The Design phase was created entirely using ChatGPT-4 without manual code revisions, dramatically reducing coding time. This pipeline was implemented in a modular way within the Galaxy platform, following the Findable-Accessible-Interoperable-Reusable (FAIR) principles. When applied to the optimization of colicin M and E1 in both Escherichia coli and HeLa-based CFPS systems, a 2- to 9-fold increase in yield was achieved in just four cycles. This framework enables reliable, automated workflows for routine synthetic biology
How to differentiate truly stochastic gene expression from structured gene expression variability ?
No full textInternational audienceGene expression is classically assessed using RNA-seq quantification. The aim of such experiments is often to compare gene expression levels across different biological conditions. Each condition is typically represented by multiple samples (replicates), which are often composed of pools of biological individuals to better estimate average gene expression levels.Pooling biological individuals can mask inter-individual variations that may nevertheless have biological significance such as observed in bethedging responses. In the case of bet-hedging, a diversified response can be observed between individuals at integrated phenotypic levels, underpinned by molecular regulations that also varies between individuals. However, molecular regulations should remain coherent and structured at the scale of the individual.</div