Pelagic population dynamics of Aurelia sp in French Mediterranean lagoons

The pelagic dynamics of the cosmopolitan scyphozoan Aurelia sp. was investigated in three French Mediterranean lagoons, Thau, Berre and Bages-Sigean, which harbour resident populations. The annual cycles showed a common univoltine pattern in all lagoons where the presence of pelagic stages in the water column lasted similar to 8 months. Field observations showed a release of ephyrae in winter time followed by pronounced growth between April and July, when individuals reached the largest sizes, before disappearing from the water column. Maximum abundance of ephyrae and medusae were registered in Thau. Medusae abundance attained a maximum of 331 ind 100 m(-3) in Thau, 18 ind 100 m(-3) in Berre and 7 ind 100 m(-3) in Bages-Sigean lagoons. Temperature and zooplankton abundance appeared as leading factors of growth, where Bages-Sigean showed the population with higher growth rates (2.66 mm day(-1)) and maximum size (32 cm), followed by Thau (0.57-2.56 mm day(-1); 22.4 cm) and Berre (1.57-2.22 mm day(-1); 17 cm). The quantification of environmental windows used by the species showed wider ranges than previously reported in the Mediterranean Sea, which suggests a wide ecological plasticity of Aurelia spp. populations in north-western Mediterranean lagoons.GELAMED project; Total foundation [189 - "Recherche" 18902 C]; EC2CO "Ecosphere Continentale et Cotiere" programme through the DYNAMO project; OSU-OREM

Un modèle économique et social pour la conservation de la biodiversité : des filières oléagineuses durables issues de produits forestiers non ligneux (PFNL) pour préserver la Réserve de Faune du Dja (RFD) au Cameroun

Cet article présente un modèle socioéconomique innovant mis en place en périphérie d’une zone à haute biodiversité : la Réserve de Faune du Dja (RFD), au Cameroun. Les produits forestiers non ligneux (PFNL) de la RFD sont depuis toujours utilisés par les populations locales pour des mets ou remèdes traditionnels. L’objectif de ce projet collaboratif associatif/privé a été de structurer les filières PFNL, afin que les populations bénéficiaires, en particulier les femmes, puissent en tirer les revenus nécessaires à leur développement. Grâce à cette alternative au braconnage, les communautés locales trouvent un intérêt économique à protéger et gérer durablement la forêt

Inflammatory control in AIDS-resistant non human primates

International audienceAfrican non human primates are natural hosts of SIV. The infection is non-pathogenic despite plasma viral load levels similar to those in HIV-1 infected humans and SIVmac-infected macaques (MAC) progressing towards AIDS. The most striking difference between non-pathogenic SIV and pathogenic HIV-1/SIVmac infections is the lack of chronic T cell activation in natural hosts. In HIV and SIVmac infections, chronic T cell activation is known to drive CD4+T cell depletion. Intense research efforts are worldwide put on the search of the mechanisms that can control chronic T cell activation in HIV/SIV infections. Innate immune responses play a determinant role in the regulation of T cell activation profiles. Type I interferons (IFN-I) are part of the first-wave response of the innate immune system in viral infections. We compared the IFN-I responses between pathogenic (MAC) and non-pathogenic SIV infections (African Green monkey, AGM) at the level of blood and lymph nodes (LN) during the early and chronic stage of infection. During the acute SIVagm infection, we detected high amounts of IFN-α in the plasma of AGMs, although the mean levels at the peak were three times lower than in MAC. The microarray data revealed a rapid and strong up-regulation of type I Interferon-Stimulated Genes (ISG) in AGMs during acute SIVagm infection. ISGs denote the in vivo activity of IFN-I. Using a functional assay, we demonstrated that low IFN-α concentrations (50 times lower than the IFN-α levels in plasma at the peak) were sufficient to induce strong ISG responses in AGM and MAC cells. Surprisingly, our direct comparison of blood and LNs showed that ISG induction was broader in blood of AGMs than in MAC, while in LN, it was the contrary. Thus, in AGMs, less ISG were induced in LNs as compared to MAC already during the acute phase of infection. Moreover, our tight kinetic analysis showed that this ISG expression was efficiently controlled after day 28 post-infection in AGMs, while in MAC the ISGs expression remained uncontrolled. Finally, we identified genes that were differentially expressed between the two species and which might be involved in the discriminating responses. Altogether, this shows that AGMs are capable to mount a well coordinated and efficient regulative response to innate immune activation

Study of the factors influencing the sugar beet conservation, and of physiological changes during storage links to the industrial quality

Á la recherche de solutions innovantes et prometteuses pour I'adaptation à l'abolition des quotas de production, Tereos, coopérative agricole, leader du marché du sucre en France, s'intéresse aux changements physiologiques subis par les racines de betteraves sucrières au cours du stockage. L'étude des facteurs impactant le stockage des racines, I'analyse des modifications physiques et biochimiques, et l'identification d'indicateurs de dégradation ont fait I'objet de cette thèse. Ce travail a été mené en collaboration avec le service industriel. Le lien entre la qualité agronomique et la qualité industrielle des racines est pour la première fois abordé dans un projet commun. En effet, les transformations physiques et biochimiques subies par les racines pendant la conservation en silo induisent la production de nouvelles molécules, dont certaines sont nuisibles à l'extraction du saccharose. Par des tests de résistances physiques et des analyses chromatographiques, certains changements physiologiques des racines sont identifiés, et les pertes en sucre au cours du stockage sont approfondies. Grâce à I'introduction de projets nouveaux, tels que l'étude des composés organiques volatils et les analyses microbiologiques, des indicateurs de dégradation des racines sont suggérés.Searching for innovative and favourable solutions in order to adapt to the abolition of production quotas, Tereos, an agricultural cooperative, leader of the French sugar market, is interested in the physiological changes which occur in the sugar beet roots during storage. The study of factors affecting the storability of roots, the analysis of physical and biochemical changes, and the identification of degradation indicators, are the main objectives of this thesis. This work was carried out in collaboration with the industrial direction. The link between the agronomical quality and the industrial quality is addressed for the first time in a joint project. Indeed, the physical and biochemical transformations suffered by roots during the conservation in piles induce the production of new molecules, and some of them are harmful for the sucrose extraction.With physical resistance tests and chromatographic analysis, some of the physiological changes of the roots are identified, and the sugar losses during storage are extended. Thanks to the introduction of new projects, as the study of volatile organic compounds and microbiological analysis, indicators of root degradation are suggested

Sensationnalisme et désinformation

La presse à sensation réside sur des rhétoriques de captation du lecteur qui jouent sur le registre de l'exclusivité et de la nouveauté. On assiste donc à la construction d'un objet informationnel qui utilise le sensationnalisme comme rhétorique. Mais poussée à son extrême, cette rhétorique aboutit à quelque chose que l'on pourrait appeler désinformation, par défaut, mais qui ne se réduit pas simplement à l'utilisation outrancière du mensonge. En fait, la désinformation en tant que procédure donne lieu à la constitution d'un leurre informationnel. Mais en deçà du contenu des messages, il y a un cadre de lecture ou horizon d'attente de l'information qui se met en place par la répétition des mêmes formes

Étude des facteurs influençant la conservation des racines de betteraves sucrières, et des changements physiologiques au cours du stockage en lien avec la qualité industrielle

Searching for innovative and favourable solutions in order to adapt to the abolition of production quotas, Tereos, an agricultural cooperative, leader of the French sugar market, is interested in the physiological changes which occur in the sugar beet roots during storage. The study of factors affecting the storability of roots, the analysis of physical and biochemical changes, and the identification of degradation indicators, are the main objectives of this thesis. This work was carried out in collaboration with the industrial direction. The link between the agronomical quality and the industrial quality is addressed for the first time in a joint project. Indeed, the physical and biochemical transformations suffered by roots during the conservation in piles induce the production of new molecules, and some of them are harmful for the sucrose extraction.With physical resistance tests and chromatographic analysis, some of the physiological changes of the roots are identified, and the sugar losses during storage are extended. Thanks to the introduction of new projects, as the study of volatile organic compounds and microbiological analysis, indicators of root degradation are suggested.Á la recherche de solutions innovantes et prometteuses pour I'adaptation à l'abolition des quotas de production, Tereos, coopérative agricole, leader du marché du sucre en France, s'intéresse aux changements physiologiques subis par les racines de betteraves sucrières au cours du stockage. L'étude des facteurs impactant le stockage des racines, I'analyse des modifications physiques et biochimiques, et l'identification d'indicateurs de dégradation ont fait I'objet de cette thèse. Ce travail a été mené en collaboration avec le service industriel. Le lien entre la qualité agronomique et la qualité industrielle des racines est pour la première fois abordé dans un projet commun. En effet, les transformations physiques et biochimiques subies par les racines pendant la conservation en silo induisent la production de nouvelles molécules, dont certaines sont nuisibles à l'extraction du saccharose. Par des tests de résistances physiques et des analyses chromatographiques, certains changements physiologiques des racines sont identifiés, et les pertes en sucre au cours du stockage sont approfondies. Grâce à I'introduction de projets nouveaux, tels que l'étude des composés organiques volatils et les analyses microbiologiques, des indicateurs de dégradation des racines sont suggérés

Étude des facteurs influençant la conservation des racines de betteraves sucrières, et des changements physiologiques au cours du stockage en lien avec la qualité industrielle

Searching for innovative and favourable solutions in order to adapt to the abolition of production quotas, Tereos, an agricultural cooperative, leader of the French sugar market, is interested in the physiological changes which occur in the sugar beet roots during storage. The study of factors affecting the storability of roots, the analysis of physical and biochemical changes, and the identification of degradation indicators, are the main objectives of this thesis. This work was carried out in collaboration with the industrial direction. The link between the agronomical quality and the industrial quality is addressed for the first time in a joint project. Indeed, the physical and biochemical transformations suffered by roots during the conservation in piles induce the production of new molecules, and some of them are harmful for the sucrose extraction.With physical resistance tests and chromatographic analysis, some of the physiological changes of the roots are identified, and the sugar losses during storage are extended. Thanks to the introduction of new projects, as the study of volatile organic compounds and microbiological analysis, indicators of root degradation are suggested.Á la recherche de solutions innovantes et prometteuses pour I'adaptation à l'abolition des quotas de production, Tereos, coopérative agricole, leader du marché du sucre en France, s'intéresse aux changements physiologiques subis par les racines de betteraves sucrières au cours du stockage. L'étude des facteurs impactant le stockage des racines, I'analyse des modifications physiques et biochimiques, et l'identification d'indicateurs de dégradation ont fait I'objet de cette thèse. Ce travail a été mené en collaboration avec le service industriel. Le lien entre la qualité agronomique et la qualité industrielle des racines est pour la première fois abordé dans un projet commun. En effet, les transformations physiques et biochimiques subies par les racines pendant la conservation en silo induisent la production de nouvelles molécules, dont certaines sont nuisibles à l'extraction du saccharose. Par des tests de résistances physiques et des analyses chromatographiques, certains changements physiologiques des racines sont identifiés, et les pertes en sucre au cours du stockage sont approfondies. Grâce à I'introduction de projets nouveaux, tels que l'étude des composés organiques volatils et les analyses microbiologiques, des indicateurs de dégradation des racines sont suggérés

Neon diffusion in goethite, α-FeO(OH): a theoretical multi-scale study

International audienceThe neon diffusion behavior in goethite has been investigated for the purpose of geological (U-Th)/Ne dating, as Ne produced in goethite by nucleogenic reactions related to natural U and Th alpha decay can diffuse out of the crystal. According to previous works, a multi-scale computational approach combining Density Functional Theory studies at the atomic scale and Kinetic Monte Carlo simulations at the macroscopic scale has been used to determine Ne diffusion behavior in goethite. Periodic-DFT calculations have been performed to study the structural, electronic, and magnetic properties of goethite, and therefore to identify the Ne insertion sites in pure defect-free goethite as well as in goethite containing iron-aluminum substitution and goethite containing crystallographic defects, to obtain a crystal structure closest to a natural goethite crystal. The Nudged Elastic Band method was used to define the minimum energy pathway for Ne migration, between neighboring interstitial sites. The Climbing Image Nudged Elastic Band method was adopted to obtain more accuracy on the transition state. The 3-dimensional random walk of Ne jumps between interstitial sites was simulated using the Kinetic Monte Carlo method. We found that a Ne atom diffuses in pure defect-free goethite following a zig-zag pathway along the unoccupied channel of goethite, with an effective activation energy of E-a = 0.50 eV and a pre-exponential factor of D-0 = 6.38 x 10(-4) cm(2) s(-1). Moreover, the iron-aluminum substitution induces a small volume contraction of the unoccupied channel, which increases the energy barrier of Ne diffusion to 0.66 eV. Nevertheless, this energy barrier remains insufficient to retain Ne atom in the goethite structure at surface temperature. However, crystallographic defects impact strongly Ne diffusivity in goethite. In the case of a Schottky defect, i.e. a large vacancy, the Ne atom is retained in the new stable site generated by the vacancy. In the case of a hydrated Fe vacancy, steric constraints remain a barrier that inhibit the Ne jumping between two adjacent unoccupied channels

Marine Microbial Food Web Networks During Phytoplankton Bloom and Non-bloom Periods: Warming Favors Smaller Organism Interactions and Intensifies Trophic Cascade

International audienceMicrobial food web organisms are at the base of the functioning of pelagic ecosystems and support the whole marine food web. They are very reactive to environmental changes and their interactions are modified in response to different productive periods such as phytoplankton bloom and non-bloom as well as contrasted climatic years. To study ecological associations, identify potential interactions between microorganismsand study the structure of the microbial food web in coastal waters, a weekly monitoring was carried out in the Thau Lagoon on the French Mediterranean coast. The monitoring lasted from winter to late spring during two contrasting climatic years, a typical Mediterranean (2015) and a year with an extreme warm winter (2016). Correlation networks comprising 110 groups/taxa/species were constructed to characterize potential possible interactions between the microorganisms during bloom and non-bloom periods. Complex correlation networks during the bloom anddominated by negative intraguild correlations and positive correlations of phytoplankton with bacteria. Such pattern can be interpreted as a dominance of competition and mutualism. In contrast, correlation networks during the non-bloom period were less complex and mostly dominated by tintinnids associations with bacteria mostly referring to potential feeding on bacteria, which suggests a shift of biomass transfer from phytoplankton-dominated food webs during bloom to more bacterioplankton-based food webs during non-bloom. Inter-annual climatic conditions significantly modified the structure of microbial food webs. The warmer year favored relationships among smaller group/taxa/species at the expense of large phytoplankton and ciliates, possibly due to an intensification of the trophic cascade with a potential shift in energy circulation through microbial food web. Our study compares a typical Mediterranean spring with another mimicking the prospected intensification of global warming; if such consideration holds true, the dominance of future coastal marine ecosystems will be shifted from the highly productive herbivorous food web to the less productive microbial food web.Microbial food web organisms are at the base of the functioning of pelagic ecosystems and support the whole marine food web. They are very reactive to environmental changes and their interactions are modified in response to different productive periods such as phytoplankton bloom and non-bloom as well as contrasted climatic years. To study ecological associations, identify potential interactions between microorganismsand study the structure of the microbial food web in coastal waters, a weekly monitoring was carried out in the Thau Lagoon on the French Mediterranean coast. The monitoring lasted from winter to late spring during two contrasting climatic years, a typical Mediterranean (2015) and a year with an extreme warm winter (2016). Correlation networks comprising 110 groups/taxa/species were constructed to characterize potential possible interactions between the microorganisms during bloom and non-bloom periods. Complex correlation networks during the bloom anddominated by negative intraguild correlations and positive correlations of phytoplankton with bacteria. Such pattern can be interpreted as a dominance of competition and mutualism. In contrast, correlation networks during the non-bloom period were less complex and mostly dominated by tintinnids associations with bacteria mostly referring to potential feeding on bacteria, which suggests a shift of biomass transfer from phytoplankton-dominated food webs during bloom to more bacterioplankton-based food webs during non-bloom. Inter-annual climatic conditions significantly modified the structure of microbial food webs. The warmer year favored relationships among smaller group/taxa/species at the expense of large phytoplankton and ciliates, possibly due to an intensification of the trophic cascade with a potential shift in energy circulation through microbial food web. Our study compares a typical Mediterranean spring with another mimicking the prospected intensification of global warming; if such consideration holds true, the dominance of future coastal marine ecosystems will be shifted from the highly productive herbivorous food web to the less productive microbial food web

Co-occurrence networks reveal the central role of temperature in structuring the plankton community of the Thau Lagoon

To identify the environmental factors that drive plankton community composition and structure in coastal waters, a shallow northwestern Mediterranean lagoon was monitored from winter to spring in two contrasting years. The campaign was based on high-frequency recordings of hydrological and meteorological parameters and weekly samplings of nutrients and the plankton community. The collected data allowed the construction of correlation networks, which revealed that water temperature was the most important factor governing community composition, structure and succession at different trophic levels, suggesting its ubiquitous food web control. Temperature favoured phytoplanktonic flagellates (Cryptophyceae, Chrysophyceae, and Chlorophyceae) and ciliates during winter and early spring. In contrast, it favoured Bacillariophyceae, dinoflagellates, phytoplankton < 6 µm and aloricate Choreotrichida during spring. The secondary factors were light, which influenced phytoplankton, and wind, which may regulate turbidity and the nutrient supply from land or sediment, thus affecting benthic species such as Nitzschia sp. and Uronema sp. or salinity-tolerant species such as Prorocentrum sp. The central role of temperature in structuring the co-occurrence network suggests that future global warming could deeply modify plankton communities in shallow coastal zones, affecting whole-food web functioning