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Les Outre-mer face à la bifurcation écologique. Des territoires pionniers ?
No full textInternational audienceLes Outre-mer, « fers de lance de la transition écologique » ? Depuis quelques années, la République française s’attache à lier le destin de ses territoires ultramarins à celui de la question écologique. Qu’il s’agisse de protection de la biodiversité, de gestion des risques, d’économie circulaire ou d’autonomie énergétique, cet appel à l’exemplarité s’appuie souvent sur la métaphore du « laboratoire », qui se prête bien à la quête d’un remède aux nombreux maux que connaissent ces territoires : chômage, violence, cherté de la vie, etc.Cet ouvrage propose une mise en perspective de la situation des Outre-mer atlantiques, à travers l’exploration des principaux domaines d’action publique dont relèvent les enjeux environnementaux aux Antilles et en Guyane. À l’heure des grandes transitions sociétales, la promotion des anciennes colonies départementalisées en « laboratoires du développement durable » révèle une vision expérimentale attachée de longue date à ces territoires. Appeler ces derniers à montrer l’exemple en matière d’écologie, après qu’ils ont été successivement soumis à la brutalité de l’extractivisme colonial et nourris à l’idéologie du progrès modernisateur, n’a pourtant rien d’évident.Sous ces diverses empreintes de la « colonialité » émergent des revendications d’acteurs et de pouvoirs locaux en quête de sens et d’émancipation, qui s’avèrent inséparables de l’expression d’une subjectivité environnementale propre, bien qu’encore incertaine et fragile. En sondant la crise écologique actuelle à l’aune des « laboratoires créoles », cette enquête inédite entre alors en résonance avec de nombreuses autres questions (institutionnelle, scientifique, autochtone, etc.), au cœur de la France des Suds, qu’elle contribue à éclairer différemment.Cet ouvrage s’adresse en priorité aux étudiants, chercheurs et enseignants-chercheurs, ainsi qu’à tous les praticiens de l’action publique, intéressés par les changements environnementaux globaux et les rapports Nords-Suds
Using species ranges and macroeconomic data to fill the gap in costs of biological invasions
No full textInternational audienceBiological invasions threaten global biodiversity, human well-being and economies. Many regional and taxonomic syntheses of monetary costs have been produced recently but with important knowledge gaps owing to uneven geographic and taxonomic research intensity. Here we combine species distribution models, macroeconomic data and the InvaCost database to produce the highest resolution spatio-temporal cost estimates currently available to bridge these gaps. From a subset of 162 invasive species with ‘highly reliable’ documented costs at the national level, our interpolation focuses on countries that have not reported any costs despite the known presence of invasive species. This analysis demonstrates a substantial underestimation, with global costs potentially estimated to be 1,646% higher for these species than previously recorded. This discrepancy was uneven geographically and taxonomically, respectively peaking in Europe and for plants. Our results showed that damage costs were primarily driven by gross domestic product, human population size, agricultural area and environmental suitability, whereas management expenditure correlated with gross domestic product and agriculture areas. We also found a lag time for damage costs of 46 years, but management spending was not delayed. The methodological predictive approach of this study provides a more complete view of the economic dimensions of biological invasions and narrows the global disparity in invasion cost reporting
Colorless Dye Sensitized Solar Cells for Building Integration
No full textInternational audienceTransparent photovoltaics (TPV) is an emerging and disruptive technology in which the solar cells selectively transmit the visible light to human eyes harvesting UV and/or NIR photons. [1] TPV is attractive as it widens the deployment of PV into new sectors, like building integrated photovoltaics (BIPV), greenhouses, car windows and sunglasses, thus providing an immense potential to generate solar electricity beyond the conventional rooftops and solar power plants. One possible approach to TPV is based on wavelength-selective absorbers where the dye requires an absorption far from the photopic response of the human eye.Limited classes of dyes possess energetic levels that can ensure an efficient injection while having a bandgap sufficiently narrow to selectively absorb the NIR region. [2] Among these classes, polymethine dyes (cyanines and squaraines) are promising for their high molar extinction coefficient and easily tunable properties through modification of central core or lateral units. Cyanines in particular have already been investigated for dye sensitized solar cell (DSSC) devices with promising results in terms of transparency and performance. Fully transparent and colorless DSSC were built reaching 80 % transmittance in complete devices. [3,4]The synthesis of new series of cyanines and squaraines have been performed in a one-step reaction under microwave heating, saving time and money in the process, and even increasing yields and purity. A simple crystallization of the crude products yielded very low cost and industrially scalable products.These new sensitizers have been deeply characterized in terms of their optical, photophysical and electrochemical properties, showing interesting structure/property relationships. Finally, photovoltaic performances have been evaluated in lab-scale DSSCs and optimized by different anode modifications and electrolyte formulations
Thermal tolerance and vulnerability to climate warming in the freshwater shrimp Atyaephyra desmarestii and Caridina multidentata
No full textInternational audienceFreshwater shrimp play crucial roles in aquatic ecosystems, yet their vulnerability to climate change remains poorly understood. This study investigates the thermal tolerance and vulnerability to climate warming of two important freshwater shrimp species with contrasting ecological preferences, Atyaephyra desmarestii and Caridina multidentata. Critical thermal maximum (CTMax) was assessed for different acclimation temperatures that cover the current summer range for both species, as well as for populations from different geographical origins for A. desmarestii. Both species demonstrated an excess of thermal tolerance in all conditions, as calculated with the thermal safety margins (TSM). However, the decrease of TSM with increasing acclimation temperatures suggested potential limitations in their ability to cope with future warming, particularly for the southern populations of A. desmarestii. Furthermore, while C. multidentata showed a high tolerance to extreme temperature fluctuations, it may face challenges in maintaining viable populations under projected climate change scenarios.The present study also provides a survey of the thermal limits of Caridea, thereby highlighting the necessity for further research on the thermal tolerance of shrimp to inform effective conservation strategies and mitigate the impacts of climate change
Plateforme frugale à ondes acoustiques pour la détection biochimique in situ
No full textLa Commune de Sinnamary en Guyane Française porte le projet de Centre d’Interprétation de l’Eau et des Milieux Aquatiques (CIEMA) de Guyane.Il consiste à faire évoluer la structure actuelle de la Maison de la nature des marais de Yiyi. Ses objectifs stratégiques sont :La préservation de l’écosystème,L’étude des impacts du changement climatique sur les zones humides,La découverte de l’eau et des milieux aquatiques,Le développement de l’éducation à l’Environnement et la citoyenneté pour l’eau,La mise en tourisme du site.Un séminaire de travail avec toutes les parties prenantes réunies, se tiendra les 30 et 31 octobre 2023, dans le but de structurer et de finaliser le projet.International audienc
Implications évolutives à court terme d'un supergène introgressé déterminant la taille dans une population vulnérable
No full textInternational audienceThe Thorny Skate (Amblyraja radiata) is a vulnerable species displaying a discrete size-polymorphism in the northwest Atlantic Ocean (NWA). We conducted whole genome sequencing of samples collected across its range. Genetic diversity was similar at all sampled sites, but we discovered a ~31 megabase bi-allelic supergene associated with the size polymorphism, with the larger size allele having introgressed in the last ~160,000 years B.P. While both Gulf of Maine (GoM) and Canadian (CAN) populations exhibit the size polymorphism, we detected a significant deficit of heterozygotes at the supergene and longer stretches of homozygosity in GoM population. This suggests inbreeding driven by assortative mating for size in GoM but not in CAN. Coalescent-based demographic modelling reveals strong migration between regions maintaining genetic variability in the recombining genome, preventing speciation between morphs. This study highlights short-term context-dependent evolutionary consequences of a size-determining supergene providing new insights for the management of vulnerable species.Chromosomal inversions prevent recombination, thereby maintaining the specific allelic arrangement within the genes they encompass, leading to enhanced fitness 1-5 . Suites of genes in inversions are often referred to as supergenes, as they can lead to the Mendelian inheritance of complex phenotypes 6,7 . While the existence of supergene systems has long been acknowledged 8 , the accessibility of whole genome sequencing (WGS) data has significantly amplified their detection. The presence of supergene-associated traits has been shown in several systems including sociality in ants 9-13 , migratory behavior and adaptation to salinity and temperature in Atlantic cod 14-16 , and wing morphology and pattern coloration in butterflies 17,18 . Supergenes are maintained in populations by an interplay between demographic and selective processes 6 , the relative contributions of which can be difficult to disentangle without careful reconstruction of the demographic history of populations based on neutral markers. Varying selection in space and time is often invoked as one of the mechanisms to explain the long-term persistence of supergenes 1 . Yet, the limited variability resulting from recombination suppression alongside complex phenotypes may impede swift adaptative responses to rapid environmental shifts. This could critically impact survival.</p
Les molécules extractibles des bois tropicaux: Activités et potentiel de valorisation pour améliorer les propriétés des matériaux
No full textInternational audiencetransformation: at a given developmental stage, molecules with various functionalities, such as those with biocidalor repellent activities against biological aggressions, are synthesized and impregnate the various cells of theirwood. The produced metabolites, whose nature and quantity vary widely from one species to another, but alsowithin the same species depending on the growth conditions of the individuals, can be extracted by variousprocesses. These chemical compounds can be used in a variety of ways, notably in the development of additivesand protective agents for functionalizing materials and improve their technological properties. These extractionprocesses could gradually replace conventional petroleum products. The study of the unique biodiversity of thetropical forest could enable the identification of new molecules of interest in the context of such valorization. Inthis respect, the study of Guiana’s forest species represents a rich field of research for exploring the functionalitiesof Amazonian wood extractives. This article provides a non-exhaustive overview of the work carried out in thisfield research units and the recent innovations that have emerged from the activities carried out around thevalorization of extractives to improve the shaping and properties of bio- and geo-sourced materials intended forconstruction in tropical environments.Pour assurer leur longévité, plusieurs espèces d’arbres sont capables de protéger leur bois grâce à un processusde transformation chimique : à un certain stade de leur développement, des molécules aux fonctionnalités variées,comme celles ayant des activités biocides ou répulsives contre les agressions biologiques, sont synthétisées etimprègnent les différentes cellules du bois. Les métabolites alors produits, dont la nature et la quantité varientlargement d’une espèce à l’autre, mais également au sein d’une même espèce selon les conditions de croissancedes individus, peuvent être extraits par différents procédés. Ces composés chimiques trouvent différentes voiesde valorisation, notamment pour le développement d’additifs et de moyens de protection pour fonctionnaliserles matériaux afin d’améliorer leurs propriétés technologiques. Ces procédés d’extraction pourraient permettreune substitution progressive des produits conventionnels pétrosourcés. L’étude de la biodiversité végétale uniquede la forêt tropicale pourrait permettre l’identification de nouvelles molécules d’intérêt dans le cadre d’une tellevalorisation. L’étude des espèces forestières de Guyane représente en cela un champ de recherche riche pourexplorer les fonctionnalités des extractibles des bois amazoniens. Cet article dresse un bilan non exhaustif destravaux développés sur cette thématique et des innovations récentes qui ont émergées des activités menéesautour de la valorisation des extractibles pour améliorer la mise en forme et les propriétés des matériaux bioetgéo-sourcés destinés à la construction en milieu tropical
Characterization of a direct role of GnRHs in the control of spermiogenesis and steroidogenesis in the small-spotted catshark Scyliorhinus canicula
No full textInternational audienceHypothalamic gonadotropin-releasing hormone (GnRH) regulates the production of gonadotropins, which control reproduction. In elasmobranchs, unlike other gnathostomes, GnRH is released into the systemic circulation to stimulate gonadotrope cells located in the ventral lobe of the pituitary. The aim of this study was to investigate the potential role of systemic GnRH in the regulation of the testis in Scyliorhinus canicula. Phylogeny and synteny analyses identified three GnRHs and four GnRH receptor (ScGnRHR-I1, -IIa1, -IIa2 and -IIb2). In vitro functional hormone-receptor interactions using synthetic ScGnRHs showed that all ScGnRHs were effective at receptors, except ScGnRHRIIa2, at femtomolar to nanomolar concentrations, with lower efficiency for ScGnRH1/ScGnRHRIIb2. Real-time PCR analyses in a wide range of tissues, including male and female reproductive tracts, showed that all three gnrh were expressed mainly in the brain and all four gnrhr were expressed in the testis, particularly during spermiogenesis. Testicular explants containing cysts with spermatids were treated with ScGnRHs and their protein content analyzed by NanoLC-ESI-MS/MS, highlighting 1677 significantly differentially expressed proteins. Among them, the growth hormone receptor (GHR) and proteins involved in cholesterol and steroid metabolism, including several HSD17bs, were upregulated. In situ hybridization showed that ghr, hsd17b3 and hsd17b12 transcripts were localized in Sertoli cells, which are the main testicular steroidogenic cells in S. canicula. Fifteen steroids were assayed in the culture media, using LC-ESI-HRMS/MS, and an increase in 17β-estradiol concentrations was observed, consistent with hsd17b expressions. Furthermore, proteins involved in transcription and DNA structure were downregulated in response to GnRHs. In conclusion, this study showed that ScGnRHs may play a direct role in the regulation of elasmobranch testes by promoting spermiogenesis and modulating steroidogenesis
de Rousseau à Moreau de Saint-Méry : discours sur l'origine et les fondements de la musique et de la danse
No full textInternational audienc
Comparison of neuro-psychiatric disorders between older adults living in foster families or nursing homes
No full textInternational audienceProfessional foster families for dependent older adults are a housing model perceived as an alternative to nursing homes in the French West Indies. The clinical profile of older adults in foster families remains to be determined, particularly concerning neuropsychiatric symptoms (NPS) in the presence of major cognitive disorders. In this cross-sectional analysis from twin studies conducted in foster families (n = 107, mean age: 81.8 years, male/female ratio: 38/62) and nursing homes (n = 332; (mean age: 81.3 years, male/female ratio: 51/49), we compare the prevalence and severity of NPS, along with psychotropic drugs prescription, between older adults (≥ 60 years) living in both arrangements. The prevalence of major cognitive disorders and the total number of NPS (3.4 ± 2.7 in foster families vs. 3.4 ± 2.5; p = 0.946) were similar between the two groups. The prevalence of each NPS was similar except for apathy (20.0% in nursing homes vs. 8.5% in foster families, p = 0.006), aberrant motor behavior (22.1% in nursing homes vs. 36.2% in foster families, p = 0.004) and eating disorders and appetite (23.0% vs. 9.3%, respectively, p = 0.002). The use of antipsychotics was more frequent in nursing homes (36.7% vs. 26.2%, p = 0.046). This study suggests that the foster families' environment may be well suited for managing older adults with psycho-behavioral disorders. © 2025. The Author(s)