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Volcano-tectonic interaction at Santorini. The crisis of February 2025. Constraints from geodesy
No full textInternational audienceIn February 2025, a strong seismic crisis occurred 35 km nor theast of Santorini, an active volcano located in South Cyclades, Greece, a region of distributed extensional active faulting. The Global Navigation Satellite System (GNSS) data shows an inflation of the volcano since August 2024. We model it with a magma source of 7.7 × 10 6 m 3 located 3.1 km under the north-central floor of the caldera, near the inflation centre of 2011-2012. After 2025 January 24, the seismic activity, until then localized within the caldera, shifted offshore Santorini and increased with eight M w ≥ 5 events and ground motion exceeding 5 mm at Syros at 110 km from the epicentres. The GNSS data is consistent with a model of dislocation involving a south-east dipping normal fault located between the Kolumbo submarine volcano and the Anydros islet, 18 km long, 12 km wide, with a tip at 7.5 km depth and ∼3 m of slip. The ∼17.5 × 10 18 Nm corresponding seismic moment, much greater than the ∼1.5 × 10 18 Nm of the recorded earthquakes, reveals the probable occurrence of a slow-slip earthquake of equi v alent magnitude 6.8. This event might have been triggered by a small dyke injected from the inferred source beneath Santorini. Ho wever , the subsidence recorded at Santorini and Anydros is incompatible with the hypothesis of a large dyke injected beneath Kolumbo-Anydros
First identification of rhabdoviruses coinfecting tilapia (Oreochromis niloticus) in central-western Gabon
No full textThe genomic sequences of viruses TiRV1 and TiRV2 have been deposited in the GenBank database under the accession numbers PV656402 and PV656403International audienceTilapia are susceptible to a number of viral diseases that have a severe economic impact in many countries. During a mass mortality event in lakes in central-western Gabon in 2019, the first rhabdoviruses infecting tilapia were identified. Two distinct and nearly complete viral genome sequences were obtained by combining whole-genome sequencing (WGS) and Sanger sequencing of amplicons. The two viruses, which we have named "tilapia rhabdovirus 1" (TiRV1) and "tilapia rhabdovirus 2" (TiRV2), were found coinfecting a single fish. These viruses are related to, but clearly distinct from, members of the subfamily Alpharhabdovirinae. The respective roles of TiRV1 and TiRV2 in the present disease outbreak remain to be clarified. Further studies are needed to evaluate whether these viruses pose a threat to the health of this fish species throughout the region
Description phénotypique et génotypique de la leucodystrophie métachromatique dans la population pédiatrique réunionnaise. Variation du gène ARSA : identification d'un possible effet fondateur
No full textBackground: Metachromatic leukodystrophy (MLD) is a rare autosomal recessive neurodegenerative disorder that is often underrecognized and misdiagnosed. Four main phenotypes, defined by age at onset, have been described. Currently, a curative treatment through gene therapy is available, but it can only be offered to presymptomatic or early symptomatic patients. Early diagnosis is therefore crucial. In the population of La Réunion Island, we have identified specific molecular variants associated with the disease that have not been reported elsewhere. This may be explained by a founder effect, as La Réunion represents a relatively isolated genetic pool. The aim of this study was to describe the natural history and clinical presentation of MLD in La Réunion Island, and to investigate the diagnostic pathway in affected patients. Method: We conducted a monocentric, retrospective study based on the clinical data of pediatric MLD patients followed at the University Hospital of La Réunion. Between 1994 and 2024. Results: Fifteen patients were included for epidemiological analysis. Among them, ten carried the same variant, ARSA p.Arg246His (c.737G>A). All fifteen patients were analyzed for their initial medical presentation leading to diagnosis, as well as for their clinical evolution. Notably, all patients, who have been sreened, carried molecular variants specific to La Réunion and not previously reported elsewhere.Conclusion: This study provides new insights into the natural history and initial clinical presentation of MLD in the La Réunion population. It highlights the urgent need to raise awareness of the disease and to recognize its early warning signs. We further propose that preconception genetic screening should be considered for individuals from La Réunion Island.Introduction : La leucodystrophie métachromatique (LDM) est une maladie de surcharge lysosomale rare, neurodégénérative de transmission autosomique récessive, le plus souvent en lien avec des mutations du gène ARSA. Sur l’île de La Réunion, l’ensemble des patients sont porteurs de la même mutation récurrente soit à l’état homozygote soit à l’état hétérozygote composite, suggérant un possible effet fondateur. L’histoire naturelle de la maladie semble en corrélation avec le génotype. Le but étant de mettre en évidence l’existence d’une mutation récurrente dans la population réunionnaise avec un possible effet fondateur. Description de l’histoire naturelle de la maladie et établir une corrélation génotype phénotype.Méthode : Étude rétrospective, monocentrique, descriptive incluant tous les cas de LDM diagnostiqués entre 1994 et 2024 sur l’île de la Réunion.Résultats : Sur 15 patients, 10 présentaient la même mutation dans ARSA, p.Arg246His (c.737G>A), dont 2 à l’état hétérozygote composite. Ils sont tous originaires de l’île de La Réunion. On observe, en l’absence de traitement, une histoire naturelle superposable, avec une entrée dans la maladie prédominant sur l’atteinte motrice avec des chutes à répétition. L’évolution vers la grabatisation est rapide et le décès se fait généralement avant l’âge de 10 ans.La ségrégation familiale a permis le diagnostic précoce à la phase pré symptomatique d’un jeune frère qui a pu bénéficier d’une thérapie génique. Conclusion : Cette étude suggère la présence d’un effet fondateur à La Réunion en lien avec la variation dans ARSA, p.Arg246His (c.737G>A). La forme clinique est intermédiaire entre la forme infantile tardive, pour sa rapidité d’évolution, et la forme juvénile précoce, pour son mode d’entrée dans la maladie. Avec l’émergence de nouveaux traitements, notamment la thérapie génique, il est primordial que ces enfants soient diagnostiqués en pré symptomatique ou early symptomatique. La LDM pourrait être éligible au programme de dépistage néonatal
Behavior and fate of ITER-like tungsten nanoparticles in freshwater ecosystems produced during operation and maintenance
No full textInternational audienceWithin the ITER project (International Thermonuclear Experimental Reactor) an international project building a magnetic confinement device to achieve fusion as a sustainable energy source, tungsten (W) is planned to serve as a plasma-facing component (PFC) in the tokamak, a magnetic confinement device used to produce controlled thermonuclear fusion power. Post plasma-W interactions, submicron tungsten particles can be released. This study investigated the exposure of lentic freshwater ecosystems to ITER-like tungsten nanoparticles in indoor aquatic mesocosms. Monitoring included tungsten (bio)distribution, (bio)transformation, speciation, and impacts following a relevant exposure scenario (chronic, medium-term, low-dose contamination). Additionally, mechanistic studies using a combination of microfluidic cells and X-ray Absorption Spectroscopy (XAS) provided a time-resolved understanding of tungsten's oxidative dissolution in freshwater. Following contamination, tungsten persisted in the water column (over 90%), showing significant (~40%) and rapid (7 days) oxidation-dissolution and polymerization. This led to significant exposure of planktonic niches, strong affinity of polymeric tungsten species for aquatic vegetation, and potential transfer to higher trophic levels like aquatic snails. Over five weeks, the bio-physicochemical parameters of the mesocosms remained stable, and no acute impacts were observed on micro- and macro-organisms
La Gastronomie de Berchoux : le festin fondateur d’une poésie réactionnaire
No full textInternational audienc
Plant tolerance is explained by resource-based plant--nematode interactions
No full textPlant--parasitic nematodes are responsible for significant economic losses worldwide, affecting a wide range of crops. They infect and divert resources and impair plant growth. While resistance aims to limit parasite burden, tolerance is the ability of a plant to maintain its yield despite infection, which offers a complementary and potentially more sustainable strategy. Understanding how tolerance arises and operates requires mechanistic insights into host--parasite interactions and the constraints that shape them. In this study, we develop a mathematical model describing the coupled dynamics of plant growth, internal resource allocation, and nematode population processes. The model incorporates key biological mechanisms, including resource-dependent plant development, nematode infection, reproduction and feedbacks between resource limitation and parasitism. We analytically derive the basic reproduction number and identify equilibrium states, including the system extinction, healthy plantation and coexistence. Our analysis shows that coexistence strongly depends on plant resources at the time of infection, shedding light on conditions under which tolerance can emerge. Numerical simulations further explore how variations in both plant and nematode parameters influence the tolerance over a cropping season. We highlight the dual role of resource production: high production rates not only boost plant growth but also enhance nematode proliferation. There is hence a compromise to be found between favoring bigger and more productive plants, versus limiting yield losses in case of nematode infestation. This compromise is shaped by the nematode virulence and plant quantitative resistance
Seizing the FAIR-EASE project interdisciplinary opportunity to investigate the Ocean Biogeochemical data in the vicinity of the 2022 record breaking Hunga Tonga Eruption
No full textInternational audienceUnder the umbrella of the EOSC ecosystem, the FAIR-EASE project funded under HORIZON-INFRA-2021-EOSC-01-04 aims to facilitate access to interoperable data and services for earth and environmental multi-disciplinary use cases, demonstrating the capabilities to support open science (https://fairease.eu/). Based on three of its pilots more specifically: the Volcano Space Observatory pilot, the Ocean Biogeochemical Observations pilot and the Coastal Dynamic pilot, the FAIR-EASE partners would like to highlight both the synergy and the new emerging interdisciplinary collaborations and progresses that can be achieved in the framework of such a European project promoting FAIR principles. Indeed,* The Volcano Space Observatory Pilot supports the implementation of innovative web services (notably here the open access VOLCPLUME web platform) displaying a broad range of satellite and ground-based data relevant to the characterization of volcanic gas and particle properties for the near real-time monitoring of volcanic activity and atmospheric hazards.* The Ocean Biogeochemical (BGC) Observations aims to provide a common QA/QC (Quality Assessment /Quality Control) platform to the whole BGC community to enhance the BGC data quality and address fundamental scientific questions. * The webODV software, part of the Coastal Water Dynamic pilot tools, allows to display and superimpose very heterogeneous datasets (i.e. satellite surface data vs. in situ profiles data, climatology vs. in situ profiles data, observations vs. model simulations in general).Taking as a starting point, the eruption of the Hunga Tonga-Hunga Ha’apai volcano on January 15, 2022, and the availability of various satellite observations of volcanic plumes and ocean surface properties together with in situ Argo (Argo is an international program that collects information from inside the ocean using a fleet of robotic instruments that drift with the ocean currents) floats measuring BGC variables such as the chlorophyll-a and suspended particles in the eruption area, FAIR-EASE partners aim to investigate the potential impacts of such a major stratospheric eruptions a record breaking eruption in the satellite era, on the marine ecosystem. Volcano and BGC community expertise as well as tools developed and pooled on Galaxy Europe platform (Galaxy is an open-source Virtual Research Environment) during the FAIR-EASE project support scientists in their investigation
Acceptance of chikungunya vaccination: a rapid survey in Reunion island during an epidemic
No full textInternational audienceDuring the 2025 chikungunya outbreak in Réunion Island, two vaccines-IXCHIQ (live-attenuated) and VIM-KUNYA (virus-like particle)-received European Union authorization; a local campaign began in April 2025 and was temporarily adjusted for older adults after safety concerns. We assessed vaccine acceptability at the outbreak onset among residents, focusing on people with comorbidities. In January 2025, a cross-sectional web survey yielded 918 complete responses (mean age 44.5 years; 13.1 % prior chikungunya; 53.4 % healthcare workers). Acceptability was highest in the hypothetical full-reimbursement scenario (60.5 %) and was lower among women and those with prior chikungunya; healthcare workers were more likely to accept vaccination. In the hypothetical clinical-trial and self-financed scenarios, acceptability declined to 35.5 % and 20.1 %, respectively, with the same pattern of predictors. Comorbidities showed no significant association. Financing and implementation context, together with gender differences, were key drivers of uptake at the beginning of 2025 outbreak