Poissons des rivières françaises et changement climatique :impacts sur la distribution des espèces et incertitudes des projections

Les changements climatiques et leurs impacts sur la biodiversité font aujourd'hui l'objet d'une attention croissante de la part de la communauté scientifique et des gestionnaires des écosystèmes naturels. En effet, le climat influence la biologie et l'écologie des espèces animales et végétales, depuis leur physiologie jusqu'à leur répartition. Les modifications climatiques pourraient donc avoir des répercussions importantes sur les espèces et les assemblages. Au sein des écosystèmes aquatiques continentaux, les poissons de rivière sont des organismes incapables de réguler leur température corporelle et soumis à une variabilité hydrologique importante ainsi qu'à de fortes pressions anthropiques. Leur réponse aux modifications du climat actuelles et à venir a pourtant été encore peu abordée. L'objectif de ce travail de thèse est donc d'évaluer les impacts potentiels du changement climatique sur les poissons des rivières françaises, et plus particulièrement sur la distribution des espèces et la structure des assemblages. Des données fournies par l'Office National de l'Eau et des Milieux Aquatiques ainsi qu'une approche de modélisation basée sur les niches écologiques des espèces (i.e., modèles de distribution) ont été utilisées. Différentes sources d'incertitude ont également été testées dans une approche d'ensembles afin de prendre en compte la variabilité entre les impacts projetés et fournir ainsi une évaluation robuste de ces impacts. La première partie de ce travail a consisté en l'identification des principaux déterminants environnementaux qui structurent la répartition spatiale des espèces de poisson au sein des réseaux hydrographiques. Globalement, il apparaît qu'une combinaison de facteurs climatiques et de variables décrivant l'habitat local et la position des habitats au sein des réseaux hydrographiques est importante pour expliquer la distribution actuelle des espèces. De plus, les espèces ont toutes des réponses différentes aux facteurs de l'environnement. Dans un second temps, nous avons mis en évidence que le choix de la méthode statistique de modélisation de la niche écologique est crucial, les patrons actuels et futurs de distribution prédits étant fortement contrastés selon la méthode de modélisation considérée. Cette dernière s'avère même être la principale source d'incertitude dans les projections futures, bien plus encore que les modèles climatiques de circulation générale et les scénarios d'émission de gaz à effet de serre. La variabilité entre les prédictions issues de plusieurs techniques de modélisation peut être prise en compte par une approche de consensus. Un modèle consensuel basé sur la valeur moyenne de l'ensemble de prédictions est capable de prédire correctement la distribution actuelle des espèces et la composition des assemblages. Nous avons donc choisi de retenir cette approche pour évaluer au mieux les impacts potentiels du changement climatique sur les poissons des rivières françaises à la fin du 21ème siècle. Nous avons montré que la majorité des espèces de poisson pourrait être affectée par les futures modifications du climat. Seules quelques espèces d'eau froide (e.g. truite fario, chabot) pourraient restreindre leur distribution aux parties les plus apicales des réseaux hydrographiques. Au contraire, les espèces tolérant des températures plus élevées pourraient coloniser de nouveaux habitats et étendre ainsi leur répartition. Ces modifications de la distribution des espèces pourraient conduire à un réarrangement des assemblages au niveau taxonomique et fonctionnel. Une augmentation de la diversité locale et de la similarité régionale (i.e., homogénéisation) sont ainsi prédites simultanément. L'ensemble de ces résultats apporte donc des éléments sur la compréhension de la distribution des poissons d'eau douce et sur les conséquences du changement climatique qui peuvent être envisagées. Ce travail fournit ainsi une base aux acteurs de la gestion de la biodiversité afin d'initier des mesures de conservation concrètes. De plus, les considérations méthodologiques développées dans cette thèse sont une contribution importante à l'amélioration des projections issues de modèles statistiques de distribution et à la quantification de leur incertitude. ABSTRACT : Climate change and its impact on biodiversity are receiving increasing attention from scientists and people managing natural ecosystems. Indeed, climate has a major influence on the biology and ecology of fauna and flora, from physiology to distribution. Climate change may thus have major consequences on species and assemblages. Among freshwater ecosystems, stream fish have no physiological ability to regulate their body temperature and they have to cope with streams' hydrological variability and strong anthropogenic pressures. Yet their response to current and future climate change has been poorly studied. The aim of this PhD thesis is to assess the potential impact of climate change on fish in French streams, mainly on species distribution and assemblages' structure. Data provided by the Office National de l'Eau et des Milieux Aquatiques combined with a modelling approach based on species' ecological niche (i.e., distribution models) have been used. Several sources of uncertainty have also been considered in an ensemble modeling framework in order to account for the variability between projected impacts and to provide reliable estimates of such impact. First, we have identified the main environmental factors that determine the spatial distribution of fish species within river networks. Overall, it appears that a combination of both climatic variables and variables describing the local habitat and its position within the river network is important to explain the current species distribution. Moreover, each fish species responded differently to the environmental factors. Second, we have highlighted that the choice of the statistical method used to model the fish ecological niche is crucial given that the current and future patterns of distribution predicted by different statistical methods vary significantly. The statistical method appears to be the main source of uncertainty, resulting in more variability in projections than the global circulation models and greenhouse gas emission scenarios. The variability between predictions from several statistical methods can be taken into account by a consensus approach. Consensual predictions based on the computation of the average of the whole predictions ensemble have achieved accurate predictions of the current species distribution and assemblages' composition. We have therefore selected this approach to assess the potential impacts of climate change on fish in French streams at the end of the 21st century with the highest degree of confidence. We have found that most fish species could be sensitive to the future climate modifications. Only a few cold-water species (i.e., brown trout, bullhead) could restrict their distribution to the most upstream parts of river networks. On the contrary, cool- and warm-water fish species could colonize many newly suitable habitats and expand strongly their distribution. These changes of species distribution could lead to a rearrangement of fish assemblages both at the taxonomic and functional levels. An increase in local diversity together with an increase in regional similarity (i.e., homogenization) are therefore expected. All these results bring new insights for the understanding of stream fish species distribution and expected consequences of climate change. This work thus provides biodiversity managers and conservationists with a basis to take efficient preservation measures. In addition, methodological developments considered in this PhD thesis are an important contribution to the improvements of projections by statistical models of species distribution and to the quantification of their uncertainty

Etching suspended superconducting hybrid junctions from a multilayer

A novel method to fabricate large-area superconducting hybrid tunnel junctions with a suspended central normal metal part is presented. The samples are fabricated by combining photo-lithography and chemical etch of a superconductor - insulator - normal metal multilayer. The process involves few fabrication steps, is reliable and produces extremely high-quality tunnel junctions. Under an appropriate voltage bias, a significant electronic cooling is demonstrated

A multi-faceted framework of diversity for prioritizing the conservation of fish assemblages

Floodplain waterbodies and their biodiversity are increasingly threatened by human activities. Given the limited resources available to protect them, methods to identify the most valuable areas for biodiversity conservation are urgently needed. In this study, we used freshwater fish assemblages in floodplainwaterbodies to propose an innovative method for selecting priority areas based on four aspects of their diversity: taxonomic (i.e. according to species classification), functional (i.e. relationship between speciesand ecosystem processes), natural heritage (i.e. species threat level), and socio-economic (i.e. species interest to anglers and fishermen) diversity. To quantitatively evaluate those aspects, we selected nine indices derived either from metrics computed at the species level and then combined for each assemblage (species rarity, origin, biodiversity conservation concern, functional uniqueness, functional originality, fishing interest), or from metrics directly computed at the assemblage level (species richness, assemblage rarity, diversity of biological traits). Each of these indices belongs to one of the four aspects of diversity. A synthetic index defined as the sum of the standardized aspects of diversity was used to assess the multifaceted diversity of fish assemblages. We also investigated whether the two main environmental gradients at the catchment (distance from the sea) and at the floodplain (lateral connectivity of the waterbodies) scales influenced the diversity of fish assemblages, and consequently their potential conservation value. Finally, we propose that the floodplain waterbodies that should be conserved as a priority are those located in the downstream part of the catchment and which have a substantial lateral connectivity with the main channel

Flare-IBD: development and validation of a questionnaire based on patients’ messages on an internet forum for early detection of flare in inflammatory bowel disease: study protocol

International audienceIntroduction: Crohn’s disease and ulcerative colitis, the two major forms of inflammatory bowel disease (IBD), are chronic disabling conditions characterised by flares followed by periods of remission. However, patients with IBD are seen every 3–6 months in the outpatient clinic, and the occurrence of a flare between two outpatient visits is not captured. To our knowledge, there is no validated patient-reported outcome (PRO) tool to measure the phenomenon of flare in IBD. This study aimed to use an innovative methodology to collect messages posted by patients in an internet forum for developing and validating a PRO measuring flare in IBD.Methods and analysis: The design involves (1) computer engineering sciences for scraping extraction of messages posted in an internet forum and for identification of messages related to flare; (2) qualitative methods for thematic content analyse of the messages posted, for candidate items generation, for items selection (Delphi process) and for items adjustment (‘think-aloud’ interviews) and (3) quantitative methods for psychometricvalidation of the PRO.Ethics and dissemination: Ethical approval was obtained from the Comité de Protection des Personnes (CPP) CPP Nord-Ouest I (19.07.15.44139) in November 2019. The project aims to provide a tool to evaluate IBD flare in current medical practice that is constructed with patients’ perspectives. Items generation from a source corresponding to exchanges in an internet forum is an innovative method in this field and provides awider coverage of qualitative data. If such a forum can result in interesting material, then this could be a new methodological perspective for generating items for questionnaires. Findings will be reported and disseminated widely through international peer-reviewed journal publications, oral and poster presentations at scientific conference

NMDA receptor dysfunction contributes to impaired brain-derived neurotrophic factor-induced facilitation of hippocampal synaptic transmission in a Tau transgenic model.

While the spatiotemporal development of Tau pathology has been correlated with occurrence of cognitive deficits in Alzheimer's patients, mechanisms underlying these deficits remain unclear. Both brain-derived neurotrophic factor (BDNF) and its tyrosine kinase receptor TrkB play a critical role in hippocampus-dependent synaptic plasticity and memory. When applied on hippocampal slices, BDNF is able to enhance AMPA receptor-dependent hippocampal basal synaptic transmission through a mechanism involving TrkB and N-methyl-d-Aspartate receptors (NMDAR). Using THY-Tau22 transgenic mice, we demonstrated that hippocampal Tau pathology is associated with loss of synaptic enhancement normally induced by exogenous BDNF. This defective response was concomitant to significant memory impairments. We show here that loss of BDNF response was due to impaired NMDAR function. Indeed, we observed a significant reduction of NMDA-induced field excitatory postsynaptic potential depression in the hippocampus of Tau mice together with a reduced phosphorylation of NR2B at the Y1472, known to be critical for NMDAR function. Interestingly, we found that both NR2B and Src, one of the NR2B main kinases, interact with Tau and are mislocalized to the insoluble protein fraction rich in pathological Tau species. Defective response to BDNF was thus likely related to abnormal interaction of Src and NR2B with Tau in THY-Tau22 animals. These are the first data demonstrating a relationship between Tau pathology and synaptic effects of BDNF and supporting a contribution of defective BDNF response and impaired NMDAR function to the cognitive deficits associated with Tauopathies

Epilepsy with migrating focal seizures

To report new sporadic cases and 1 family with epilepsy of infancy with migrating focal seizures (EIMFSs) due to KCNT1 gain-of-function and to assess therapies' efficacy including quinidine. We reviewed the clinical, EEG, and molecular data of 17 new patients with EIMFS and KCNT1 mutations, in collaboration with the network of the French reference center for rare epilepsies. The mean seizure onset age was 1 month (range: 1 hour to 4 months), and all children had focal motor seizures with autonomic signs and migrating ictal pattern on EEG. Three children also had infantile spasms and hypsarrhythmia. The identified KCNT1 variants clustered as "hot spots" on the C-terminal domain, and all mutations occurred de novo except the p.R398Q mutation inherited from the father with nocturnal frontal lobe epilepsy, present in 2 paternal uncles, one being asymptomatic and the other with single tonic-clonic seizure. In 1 patient with EIMFS, we identified the p.R1106Q mutation associated with Brugada syndrome and saw no abnormality in cardiac rhythm. Quinidine was well tolerated when administered to 2 and 4-year-old patients but did not reduce seizure frequency. The majority of the KCNT1 mutations appear to cluster in hot spots essential for the channel activity. A same mutation can be linked to a spectrum of conditions ranging from EMFSI to asymptomatic carrier, even in the same family. None of the antiepileptic therapies displayed clinical efficacy, including quinidine in 2 patients

Mutations in TUBG1, DYNC1H1, KIF5C and KIF2A cause malformations of cortical development and microcephaly.

International audienceThe genetic causes of malformations of cortical development (MCD) remain largely unknown. Here we report the discovery of multiple pathogenic missense mutations in TUBG1, DYNC1H1 and KIF2A, as well as a single germline mosaic mutation in KIF5C, in subjects with MCD. We found a frequent recurrence of mutations in DYNC1H1, implying that this gene is a major locus for unexplained MCD. We further show that the mutations in KIF5C, KIF2A and DYNC1H1 affect ATP hydrolysis, productive protein folding and microtubule binding, respectively. In addition, we show that suppression of mouse Tubg1 expression in vivo interferes with proper neuronal migration, whereas expression of altered γ-tubulin proteins in Saccharomyces cerevisiae disrupts normal microtubule behavior. Our data reinforce the importance of centrosomal and microtubule-related proteins in cortical development and strongly suggest that microtubule-dependent mitotic and postmitotic processes are major contributors to the pathogenesis of MCD

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Poissons des rivières françaises et changement climatique (impacts sur la distribution des espèces et incertitudes des projections)

Les changements climatiques et leurs impacts sur la biodiversité font aujourd'hui l'objet d'une attention croissante de la part de la communauté scientifique et des gestionnaires des écosystèmes naturels. En effet, le climat influence la biologie et l'écologie des espèces animales et végétales, depuis leur physiologie jusqu'à leur répartition. Les modifications climatiques pourraient donc avoir des répercussions importantes sur les espèces et les assemblages. Au sein des écosystèmes aquatiques continentaux, les poissons de rivière sont des organismes incapables de réguler leur température corporelle et soumis à une variabilité hydrologique importante ainsi qu'à de fortes pressions anthropiques. Leur réponse aux modifications du climat actuelles et à venir a pourtant été encore peu abordée. L'objectif de ce travail de thèse est donc d'évaluer les impacts potentiels du changement climatique sur les poissons des rivières françaises, et plus particulièrement sur la distribution des espèces et la structure des assemblages. Des données fournies par l'Office National de l'Eau et des Milieux Aquatiques ainsi qu'une approche de modélisation basée sur les niches écologiques des espèces (i.e., modèles de distribution) ont été utilisées. Différentes sources d'incertitude ont également été testées dans une approche d'ensembles afin de prendre en compte la variabilité entre les impacts projetés et fournir ainsi une évaluation robuste de ces impacts. La première partie de ce travail a consisté en l'identification des principaux déterminants environnementaux qui structurent la répartition spatiale des espèces de poisson au sein des réseaux hydrographiques. Globalement, il apparaît qu'une combinaison de facteurs climatiques et de variables décrivant l'habitat local et la position des habitats au sein des réseaux hydrographiques est importante pour expliquer la distribution actuelle des espèces. De plus, les espèces ont toutes des réponses différentes aux facteurs de l'environnement. Dans un second temps, nous avons mis en évidence que le choix de la méthode statistique de modélisation de la niche écologique est crucial, les patrons actuels et futurs de distribution prédits étant fortement contrastés selon la méthode de modélisation considérée. Cette dernière s'avère même être la principale source d'incertitude dans les projections futures, bien plus encore que les modèles climatiques de circulation générale et les scénarios d'émission de gaz à effet de serre. La variabilité entre les prédictions issues de plusieurs techniques de modélisation peut être prise en compte par une approche de consensus. Un modèle consensuel basé sur la valeur moyenne de l'ensemble de prédictions est capable de prédire correctement la distribution actuelle des espèces et la composition des assemblages. Nous avons donc choisi de retenir cette approche pour évaluer au mieux les impacts potentiels du changement climatique sur les poissons des rivières françaises à la fin du 21ème siècle. Nous avons montré que la majorité des espèces de poisson pourrait être affectée par les futures modifications du climat. Seules quelques espèces d'eau froide (e.g. truite fario, chabot) pourraient restreindre leur distribution aux parties les plus apicales des réseaux hydrographiques. Au contraire, les espèces tolérant des températures plus élevées pourraient coloniser de nouveaux habitats et étendre ainsi leur répartition. Ces modifications de la distribution des espèces pourraient conduire à un réarrangement des assemblages au niveau taxonomique et fonctionnel. Une augmentation de la diversité locale et de la similarité régionale (i.e., homogénéisation) sont ainsi prédites simultanément. L'ensemble de ces résultats apporte donc des éléments sur la compréhension de la distribution des poissons d'eau douce et sur les conséquences du changement climatique qui peuvent être envisagées. Ce travail fournit ainsi une base aux acteurs de la gestion de la biodiversité afin d'initier des mesures de conservation concrètes. De plus, les considérations méthodologiques développées dans cette thèse sont une contribution importante à l'amélioration des projections issues de modèles statistiques de distribution et à la quantification de leur incertitude.Climate change and its impact on biodiversity are receiving increasing attention from scientists and people managing natural ecosystems. Indeed, climate has a major influence on the biology and ecology of fauna and flora, from physiology to distribution. Climate change may thus have major consequences on species and assemblages. Among freshwater ecosystems, stream fish have no physiological ability to regulate their body temperature and they have to cope with streams' hydrological variability and strong anthropogenic pressures. Yet their response to current and future climate change has been poorly studied. The aim of this PhD thesis is to assess the potential impact of climate change on fish in French streams, mainly on species distribution and assemblages' structure. Data provided by the Office National de l'Eau et des Milieux Aquatiques combined with a modelling approach based on species' ecological niche (i.e., distribution models) have been used. Several sources of uncertainty have also been considered in an ensemble modeling framework in order to account for the variability between projected impacts and to provide reliable estimates of such impact. First, we have identified the main environmental factors that determine the spatial distribution of fish species within river networks. Overall, it appears that a combination of both climatic variables and variables describing the local habitat and its position within the river network is important to explain the current species distribution. Moreover, each fish species responded differently to the environmental factors. Second, we have highlighted that the choice of the statistical method used to model the fish ecological niche is crucial given that the current and future patterns of distribution predicted by different statistical methods vary significantly. The statistical method appears to be the main source of uncertainty, resulting in more variability in projections than the global circulation models and greenhouse gas emission scenarios. The variability between predictions from several statistical methods can be taken into account by a consensus approach. Consensual predictions based on the computation of the average of the whole predictions ensemble have achieved accurate predictions of the current species distribution and assemblages' composition. We have therefore selected this approach to assess the potential impacts of climate change on fish in French streams at the end of the 21st century with the highest degree of confidence. We have found that most fish species could be sensitive to the future climate modifications. Only a few cold-water species (i.e., brown trout, bullhead) could restrict their distribution to the most upstream parts of river networks. On the contrary, cool- and warm-water fish species could colonize many newly suitable habitats and expand strongly their distribution. These changes of species distribution could lead to a rearrangement of fish assemblages both at the taxonomic and functional levels. An increase in local diversity together with an increase in regional similarity (i.e., homogenization) are therefore expected. All these results bring new insights for the understanding of stream fish species distribution and expected consequences of climate change. This work thus provides biodiversity managers and conservationists with a basis to take efficient preservation measures. In addition, methodological developments considered in this PhD thesis are an important contribution to the improvements of projections by statistical models of species distribution and to the quantification of their uncertainty.TOULOUSE-INP (315552154) / SudocSudocFranceF