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Genomic and metabolomic insights into the modes-of-action of bacterial strains to control the grapevine wood pathogen, Fomitiporia mediterranea
No full textInternational audienceGrapevine trunk diseases (GTDs), particularly Esca, represent a major challenge for viticulture worldwide, leading to substantial economic losses. With no effective control treatments available, developing new methods such as biocontrol is crucial for managing GTDs. Our aim was to select biocontrol bacteria effective against the white-rot fungal pathogen Fomitiporia mediterranea (Fmed) and to investigate their mechanisms of action. A stepwise screening of 58 bacterial strains was conducted in vitro to assess their ability to inhibit Fmed growth through volatile and diffusible metabolites production. The screening was also done on wood sawdust from seven different grapevine cultivars. Out of 58 tested strains, 49 inhibited Fmed growth by over 50 % through their volatile organic compounds, only eight achieving this through their agar-diffusible metabolites. Pseudomonas lactis SV9, Pseudomonas paracarnis S45, and Paenibacillus polymyxa SV13 exhibited a strong efficacy in inhibiting Fmed on wood sawdust in a cultivar-dependent manner. We selected these strains for whole genome analysis and metabolomic profiling via LC-MS/MS for diffusible compounds and SPME GC-MS for volatile compounds. P. polymyxa SV13 inhibited Fmed primarily through diffusible metabolites, producing mainly fusaricidin-type compounds. Conversely, Pseudomonas strains acted mainly via their volatile metabolites, producing mainly the antifungal compound dimethyl disulfide. Genome analysis of the three bacterial strains revealed gene clusters responsible for regulating both direct and indirect mechanisms in biocontrol agents (BCAs). Our findings highlight the importance of comprehensive studies that combine in vitro experiments mimicking field conditions, with detailed investigations into modes of action to improve BCAs efficacy
Effects of a plant-based diet from first feeding on the intestinal expression of nutrient sensors in rainbow trout (Oncorhynchus mykiss)
No full textInternational audienceTo promote sustainable aquaculture practices, fishmeal and fish oil in aquafeeds are increasingly being replaced with more sustainable ingredients, primarily sourced from plants. However, for rainbow trout (Oncorhynchus mykiss), a carnivorous species, completely substituting marine-derived ingredients with plant-based ones results in reduced growth and significantly lower survival rates of offspring. These changes occur early in development and primarily relate to alterations in feed intake and feed efficiency. Despite this knowledge, the precise origins of these effects remain unexplored. In this study we investigated the abundance of nutrient sensors in the gastrointestinal tract (GIT) of rainbow trout fed from first feeding to 100 days with either a commercial-like diet (containing fishmeal and fish oil and a partial replacement by plant ingredients) or a completely plant-based diet. Firstly, our data revealed higher ingestion levels for trout fed with the commercial-like diet compared to the plant-based diets, regardless of the size of the feed, from their first meal up to 94 days. This difference in ingestion levels may explain the observed growth differences during this period. At genic level, results showed distinct temporal expression profiles for the mRNAs encoding the studied amino acid and fatty acid sensors in the rainbow trout GIT during the first months of life. For instance, mRNAs encoding certain transporters and receptors, such as the amino acid transporter Pept1 and the fatty acid transporter Fatp4, increased during the duration of the experiment. Conversely, others, like the amino acid transporter Lat4 and the fatty acid transporter Cd36, showed the opposite trend. Some mRNAs (e.g., ffar2a2 and ffar2a1b) were undetectable at very early stages but became detectable by day 5 or 10 post-first feeding. Additionally, the temporal profiles of appetite-regulatory hormones mRNAs generally exhibited increasing levels until days 10 or 30 after the first meal, followed by a subsequent decline. In addition, our results demonstrated slight differences in the expression of nearly all nutrient sensors and appetite-regulatory hormones at early life stages when the trout were fed a plant-based diet. Overall, our study showed that feeding a plant-based diet from first feeding does not significantly alter the gastrointestinal expression of nutrient sensors during early life stages, likely excluding this aspect as responsible for the growth problems associated with vegetable diets.</div
Eco‐Evolutionary Consequences of Selective Exploitation on Metapopulations Illustrated With Atlantic Salmon
No full textInternational audienceAlthough the eco-evolutionary consequences of dispersal and exploitation are increasingly recognised, consideration of these effects and how they interact for management and conservation remains limited. We addressed this gap by examining population exploitation within a metapopulation framework, using Atlantic salmon as a case study. We compared eco-evolutionary consequences of alternative exploitation strategies by incorporating selective exploitation based on life-history traits and spatial dimension of exploitation (i.e., whether populations were net exporters or importers of individuals). We used a demogenetic agent-based model to examine demographic and evolutionary consequences of these strategies across a gradient of population-specific exploitation rates. At the metapopulation scale, we found both lower abundance and earlier sexual maturation with increasing exploitation, particularly when fishing was selective on larger individuals. The spatial selectivity of exploitation had an overall additional detrimental effect on metapopulation performance and fisheries yield, and induced stronger evolutionary changes than when exploitation was evenly spread over all populations. We discuss the implications of metapopulation functioning for species management and how considering dispersal patterns and intensity might change how we apply harvest. Nevertheless, our findings suggest that the safest approach remains to distribute exploitation efforts evenly across all populations, especially in the absence of variation in intrinsic productivity. However, this strategy might not completely prevent negative consequences at the local scale. Therefore, we advise managers to critically assess the relevance of our results and dispersal assumptions in the specific cases they may have to deal with.This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.</div
Configurations organisationnelles en temps de crise. Bricolage organisé et bricolage organisant
No full textInternational audienc
Abondance frugale contre austérité pléthorique : pratiques de subsistance dans les Alpes françaises
No full textInternational audienceThis article looks at the contrast between the political unacceptability and great subjective difficulty of agreeing to even slight reductions in consumption for ecological reasons and the way in which, on the contrary, some populations can implement alternative lifestyle choices that correspond to much more drastic renunciations, without experiencing them as restrictions but as potentially liberating lifestyle choices that enable them to live more fully. It is based on a study of rural alternatives and neo-peasants encountered during ethnographic fieldwork carried out in the Southern French Alps during twenty or so one- to two-week stays at workplaces or food production sites. As well as developing the ways in which these lifestyles are lived and raising the question of assessing their socio-ecological footprint on a wider scale, the aim is to highlight the way in which an ecology rooted in subsistence practices and based on a complete recomposition of relations to wage-earning, work, consumption and the State contrasts with an institutional approach to the rationing necessary against a backdrop of disaster, which aims to impose restrictions without changing the fundamental structures of society. This will involve questioning the moralising approach of restriction and imposed sobriety as it appears in the paradox of a plethoric consumer society in a permanent state of austerity opposed to the possibility of subjective abundance in simplicity.Cet article s’interroge sur l’écart entre, d’une part, l’inacceptabilité politique et la grande difficulté subjective de consentir à des réductions pourtant légères de la consommation pour des raisons écologiques et, d’autre part, la façon dont au contraire certaines personnes peuvent mettre en oeuvre des modes de vie alternatifs qui correspondent à des renoncements bien plus drastiques, sans pour autant les vivre comme des restrictions mais plutôt comme des choix au potentiel libérateur leur permettant de vivre plus pleinement. Il s’appuie sur l’étude de rencontres avec des personnes tentant de mettre en pratique des valeurs d’écologie et de décroissance par leurs pratiques agricoles professionnelles ou vivrières effectuées au cours d’un travail de terrain ethnographique mené dans le Sud des Alpes françaises lors d’une vingtaine de séjours d’une à deux semaines. En plus de développer les modalités régissant ces modes de vie et de poser la question de l’évaluation de leur impact socio-écologique sur une échelle plus large, il s’agit de mettre en évidence la façon dont une écologie ancrée dans les pratiques de subsistance et reposant sur une recomposition complète des relations au salariat, au travail, à la consommation et à l’État s’oppose à une approche institutionnelle du rationnement nécessaire sur fond de catastrophe qui vise à imposer des restrictions sans modifier les structures fondamentales de la société. Il s’agira alors d’interroger l’approche moralisatrice qui impose restriction et sobriété, telle qu’elle apparaît dans le paradoxe d’une société de consommation pléthorique en régime d’austérité permanent, en l’opposant à la possibilité d’une abondance subjective dans la simplicité
Le droit de veto, "arme communautaire" des populistes
No full textInternational audienceDepuis un certain nombre d’années, l’Union européenne est confrontée à la menace populiste. Si cette menace tend très largement à s’opérer par le truchement des droits constitutionnels nationaux, les récents exemples de la Hongrie et de la Pologne tendent à suggérer que les populistes ont également trouvé une « arme » au sein du droit de l’Union : le droit de veto de l’Etat membre. En effet, les dirigeants populistes au pouvoir dans ces deux Etats n’hésitent pas à faire un usage répété de ce droit afin d’entraver l’action de l’Union. Toutefois, son efficacité se révèle relativement nuancée, ce dont ne peuvent que se réjouir des institutions européennes sensiblement limitées quant aux solutions à apporter face à cette « arme communautaire »
"Le vilain qui vit un autre home od sa feme" de Marie de France - Édition, traduction et notes d'après le manuscrit BnF fr. 1593
No full textÉdition, traduction et notes du "Vilain qui vit un autre home od sa feme" de Marie de France d'après le manuscrit BnF fr. 159
Highly compressible polyacrylamide/cellulose-g-poly(methacrylic acid) hydrogels
No full textInternational audienceComposite hydrogel of cross-linked polyacrylamide (PAAm) containing cellulose-g-poly(methacrylic acid) molecular brushes (MB) as a “soft” filler was prepared by thermoinitiated radical polymerization of acrylamide in the presence of MB. Interaction between linear PAAm and MB results in decrease in PAAm viscosity at high shear rates and increase in storage modulus of mixed solution. Even low amount of MB results in increasing of ultimate compression of PAAm hydrogel, while concentration of MB in semidilute solution regime results in significant increase of hydrogel strength from 2.3 to 6.0 MPa. The use of permeable “soft” filler also allows to preserve high conductivity of hydrogel combined with improved mechanical propertie
Is reducing phosphorus inputs sufficient to reduce hypoxia in estuaries? The example of the Loire estuary
No full textInternational audienceCoastal deoxygenation is mainly attributed to excessive nutrient and organic matter inputs from anthropogenic activities. However, although mitigation strategies have been implemented to reduce nutrient inputs, the recovery of estuarine systems has often been limited. By examining long-term data from the turbid Loire estuary, which is prone to summer hypoxia, we aimed to understand the influence of these initiatives on nutrient and dissolved oxygen levels. The data showed that despite the reduction of dissolved phosphorus in the inner estuary, summer hypoxia persisted. By integrating high spatial resolution datasets, we identified nutrient sources, particularly ammonium, in the estuarine turbidity maximum zone. Nutrient recycling is likely to maintain summer hypoxia and hinder ecosystem recovery from hypoxia. A comprehensive understanding of estuarine geochemistry and internal nutrient cycling is essential to develop targeted remediation strategies and mitigate the ongoing threat of hypoxia
Efficient Lignin Precipitation from Softwood Black Liquor Using Organic Acids for Sustainable Valorization
No full textInternational audienceThe chemical industry’s transition towards sustainability necessitates the development of eco-friendly processes that can replace petrochemical derivatives. Lignin, the second most abundant plant polymer, has potential as a renewable alternative to phenolic compounds. This study investigates lignin precipitation from softwood black liquor using five organic acids (acetic, citric, lactic, malic, and oxalic) as a sustainable alternative to sulfuric acid. The precipitated lignins were subjected to comprehensive chemical and thermal characterization, revealing higher total phenolic content and enhanced reactivity when organic acids were employed. Notably, organic acid-precipitated lignins demonstrated comparable or superior purity, with ash contents below 0.50%, compared to 3.28% observed for sulfuric acid-precipitated lignin. These findings suggest that organic acids are a viable and greener alternative for lignin precipitation, promoting higher purity and yield, thus supporting lignin valorization efforts