Portail "HAL-Francophonie Afrique et Océan Indien"
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The hidden side of the co-production of small-scale fishery policy instruments in Madagascar
No full textInternational audienceThe participation of stakeholders in the design of fisheries policy instruments has emerged worldwide as good governance practice. Their participation is expected to ensure that policies are context-specific, address local needs and ecological realities, and foster effective fishery management. We used an interdisciplinary perspective from policy science, institutional economics, and sociology to challenge this common view in least developed countries through a case study of mud crab export small-scale fisheries in Madagascar. In 2021–2023, we conducted semi-structured interviews with representatives of local communities, the fishing sector, environmental non-governmental organizations, research, and administrations to study the co-production process of policy instruments regulating fishing and market activities. The results showed that non-state stakeholders' participation was effective during the design, early development, and implementation phases of instrument production although local communities contributed less than other influencing stakeholders (non-governmental organizations, experts, and exporting companies) due to power asymmetries. However, the final content of most policy instruments was determined with limited participation while the decision-making process remained under the control of the central fisheries administration. The paper highlights the visible and hidden aspects of apparent inclusive governance of the fisheries. To develop sustainable and actionable solutions to wicked resource use problems in small-scale fisheries, efforts should extend beyond opportunistic consultation to ensure meaningful contribution of local and other non-state actors to decision-making through transparent institutions
Effects of temperature variations on aquifer biogeochemistry during high-temperature thermal energy storage operation: flow-through laboratory experiment insights
No full textInternational audienceReducing the carbon footprint of building heating and cooling is essential for reaching climate change mitigation goals. Seasonal High-Temperature Aquifer Thermal Energy Storage (HT-ATES) is a promising method to achieve these goals. However, the injection of high-temperature water may significantly alter aquifer geochemistry and microbiology by influencing redox equilibria and mineral solubility, and by strongly impacting the structure and activity of microbial communities, favouring shifts toward thermophilic microorganisms and changes in metabolisms. Although microbial life is ubiquitous in aquifers, biogeochemical processes occurring under HT-ATES conditions remain poorly understood, raising concerns regarding environmental impacts, system performances and long-term sustainability.We investigated the effects of heating and cooling cycles on the structure and functions of aquifer microbial communities. HT-ATES conditions were simulated in the laboratory using a pressurised (13 bar) flow-through column with the BRGM’s BioREP platform. Groundwater from a monitoring HT-ATES well in TU Delft campus (Netherlands) was injected through the aquifer sediments while the temperature of the experimental device varied cyclically within a range typical of HT-ATES warm wells (30°C to 50°C), before a last phase returning to the natural aquifer temperature (12°C). Geochemical parameters, such as pH, redox potential, conductivity, redox-sensitive elements were monitored in circulating water at the inlet and outlet points of the column. Changes in microbial community composition of sediments and circulating water were assessed through 16S rRNA genes Illumina sequencing.Preliminary results indicate that the aquifer sediments are quartz-rich, with presence of carbonates and clay minerals, and that the groundwater is of reduced brackish Na-Cl type. While intermediate and final sediment mineralogy analysis are still ongoing, groundwater analysis show that the chemistry remained stable throughout the experiment. A gradual clogging of the column (increase of the inlet pressure) was observed. Upon opening the experimental setup, precipitates were observed at the outlet of the column. Their origin, whether chemical or biological, are under investigation.Initial microbial analysis of the groundwater revealed a dominance of bacteria (89%), with major phyla including Firmicutes, Bacteroidota, Proteobacteria, Desulfobacterota, and Spirochaetota along with Halobacterota. Many of these taxa are associated with anaerobic and slightly saline environments and include fermentative microorganisms. Several dominant groups are mesophilic and/or non-spore forming taxa. Higher and fluctuating temperatures may promote alternative, more thermotolerant microbial assemblage. Ongoing metagenomic analyses aim to determine how temperature perturbations under HT-ATES conditions influence microbial communities’ composition and possible functions and assess the implications for associated biogeochemical processes.Acknowledgements: Funded by the European Union under grant agreement 1011096566 (PUSH-IT project). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or CINEA. Neither the European Union nor CINEA can be held responsible for them
Redox behavior of Cu onto Magnetite Nanoparticles
No full textInternational audienceCopper (Cu) oxidation state distribution controls its toxicity and mobility in natural systems, and is affected by its interaction with redox-reactive minerals surfaces such as magnetite.By combining aqueous chemical analysis, X-ray absorption spectroscopy and aqueous speciation modeling, this study provides detailed mechanistic insights regarding Cu redox speciation in solution and at the surface of 10 nm-sized magnetite nanoparticles with varying stoichiometries (0.1 ≤ R = Fe(II)/Fe(III) ≤ 0.5), versus pH (4 to 9) and initial Cu(II) concentration ([Cu(II)]ini = 25 and 500 μM), with 10 mM NaCl. Cu(II) generally prevailed at the magnetite surface, with cooccurring Cu(I) from a smaller to an equal extent. Conversely, in the aqueous solution (i.e. after filtration), Cu(I) prevailed at pH > 5, hence evidencing that solution and surface redox speciation may differ. Reduction to Cu(0) was only partial and detected under the most reducing condition (for R = 0.5) at high [Cu(II)]ini, because it was limited by Cu(II)-and Cu(I)-magnetite binding.Significant oxidation Fe(II) to Fe(III) was shown responsible for this partial reduction process, which could be overcome by adding Fe(II) ions to recharge the magnetite surface, hence promoting further copper reduction to Cu(0). This study provides fundamental insights into copper-magnetite interactions and enables improved predictions of copper speciation and fate in environmental systems.</p
Impact de la restructuration des entreprises publiques sur la rentabilité post-reforme en République Démocratique du Congo : analyses et perspectives Impact of the restructuring of public enterprises on post-reform profitability in the Democratic Republic of Congo: analyses and perspectives
No full textInternational audienceAbstractThis article analyzes the impact of the restructuring of Congolese public enterprises on their post-reform profitability, using REGIDESO S.A. as a case study. The methodology combines a univariate analysis of financial indicators over the period from 2014 to 2023 and a confirmatory qualitative study with a senior manager of the company. Restructuring, understood as a reorganization process aimed at adapting structures to practical requirements and improving profitability, falls within the framework of Law No. 08/007 of 2008 in the Democratic Republic of Congo, which provides for the transformation of public enterprises into commercial companies in order to strengthen their efficiency and reduce bureaucratic inefficiencies. However, empirical results reveal an overall loss of profitability after the reform (on average ROA -0.0129, ROE -0.0173 and ROS -0.139), reflecting REGIDESO's continued inability to generate value from its assets, to remunerate its equity, and to convert its sales into profit. The study also shows that the reform, although based on clear profitability and governance objectives, did not produce the expected results: profitability remained low, deficits persisted, and the organization was marked by structural, managerial, and financial weaknesses. This was compounded by governance characterized by a lack of transparency and oversight, political pressures, and intermittent funding, further exacerbating the situation. By comparing it with similar experiences (Algeria, Morocco, and the DRC), the study emphasizes that the success of reforms depends on prerequisites such as macroeconomic consolidation, financial stabilization, and strong leadership. Thus, reform cannot be reduced to a purely technical or formal operation, but must instead be integrated into an institutional and strategic framework, a prerequisite for the sustainable improvement of the profitability of restructured public enterprises.Résumé Cet article analyse l’impact de la restructuration des entreprises publiques congolaises sur leur rentabilité post réforme, en prenant pour étude le cas de la REGIDESO. S.A. La méthodologie combine une analyse univariée des indicateurs financiers sur la période allant de 2014 à 2023 et d’une étude qualitative confirmatoire auprès d’un des hauts cadres de l’entreprise. La restructuration, entendue comme un processus de réorganisation visant à adapter les structures aux exigences pratiques et à améliorer la rentabilité, s’inscrit dans le cadre de la loi n° 08/007 de 2008 en République démocratique du Congo qui prévoit la transformation des entreprises publiques en sociétés commerciales en vue de renforcer leur efficacité et de réduire les inefficiences bureaucratiques. Cependant, les résultats empiriques révèlent une rentabilité globalement déficitaire après la réforme (en moyenne ROA -0,0129, ROE -0,0173 et ROS -0,139), traduisant l’incapacité persistante de la REGIDESO à générer de la valeur à partir de ses actifs, à rémunérer ses capitaux propres et à convertir ses ventes en bénéfice. L’étude montre également que la réforme, bien que fondée sur des objectifs clairs de rentabilité et de gouvernance, n’a pas produit les résultats attendus : la rentabilité est restée faible, les déficits persistent et une organisation marquée par des faiblesses structurelles, managériales et financières. A cela s’ajoutent une gouvernance marquée par un manque de transparence et de contrôle, des pressions politiques et un financement intermittent aggravant la situation. En comparant avec des expériences similaires (Algérie, Maroc et RDC), l’étude souligne que la réussite des réformes dépend de conditions préalables telles que l’assainissement macroéconomique, la stabilisation financière et un leadership fort. Ainsi, la réforme ne saurait être réduite à une opération purement technique ou formelle, mais elle doit plutôt s’inscrire dans une perspective institutionnelle et stratégique, condition sine qua non de l’amélioration durable de la rentabilité des entreprises publiques restructurées
A new ceramide and sterols with moderate antibiofilm activity from the underexplored polypore Mushroom <i>Lenzites acuta</i>
No full textInternational audienceLenzites acuta Berk. is a wood-decaying polypore mushroom from tropical forests that remains chemotaxonomically unexplored. In this study, the chemical constituents from the methanolic extract of its fruiting bodies yielded a new ceramide, polyporamide (1), together with three sterols: stellasterol (2), ergosterol (3), and ergosterol peroxide (4). Acetylation of the new ceramide (1) afforded a new hemi-synthetic derivative, polyporamide tetraacetate (1a). Structural elucidation was achieved by 1D and 2D NMR, ESI-MS, and comparison with literature data. The antibacterial activity of the extract and isolated compounds was assessed against Pseudomonas aeruginosa and Staphylococcus aureus. Compound 1a displayed the strongest antibacterial effect, with MIC values of 128 µg/mL (P. aeruginosa) and 64 µg/mL (S. aureus). Antibiofilm activity was evaluated using a microtiter plate assay with safranine staining at sub-MIC concentrations. Compound 4 exhibited the highest inhibition of biofilm formation, with 69.35 % inhibition against P. aeruginosa and 51.59 % against S. aureus at 128 µg/mL. Although less active than the reference drug gentamicin, compounds 1a and 4 appear as potential scaffolds for the development of antibacterial and antibiofilm agents. This study constitutes the first report on the chemical constituents of L. acuta and highlights its potential as a source of bioactive natural products
Splenic accumulation of intact Plasmodium ovale sensu lato-infected red blood cells in a patient presenting with splenic rupture
No full textInternational audienceA 35-year-old man had splenic rupture just after starting antimalarial treatment with atovaquone-proguanil followed by artesunate for acute Plasmodium ovale sensu lato infection. Spleen histology showed a 10-fold accumulation of intact P. ovale s.l. -infected erythrocytes in the spleen parenchyma compared to the general circulation. Infected erythrocytes also accumulated in small extra-splenic blood vessels, suggesting cytoadherence
Sulfur-Driven Cadmium Isotope Fractionation by Low-Molecular Weight Organic Ligands: Experimental Evidence from the Donnan Membrane Technique
No full textInternational audienceOrganic ligands have been suggested to play a key role in controlling the root-to-shoot transport and isotope fractionation of cadmium (Cd) in crops. In this work, we used the Donnan membrane technique to determine the Cd equilibrium isotope fractionation that is induced by the chelation of Cd with low-molecular weight organic ligands. While a model ligand with oxygen and nitrogen functional groups (EDTA, R-OH, R-NH) induced no significant isotope fractionation between complexed and free Cd 2+ (Δ 114/110 CdCdEDTA -freeCd = -0.08 ± 0.12‰, n = 4), the model ligand with sulfur donor groups (DMPS, R-SH) induced a strong isotope fractionation (Δ 114/110 CdCdDMPS -freeCd = -0.66 ± 0.20‰, n = 4). These experimental results indicate that binding of Cd to thiols plays a major role in retaining light Cd isotopes in roots and shoots, thereby minimizing transfer to cereal grains.Il a été suggéré que les ligands organiques jouent un rôle clé dans le contrôle du transport racine-pousse et du fractionnement isotopique du cadmium (Cd) dans les cultures. Dans le cadre de ces travaux, nous avons utilisé la technique de la membrane de Donnan pour déterminer le fractionnement isotopique à l'équilibre du Cd induit par la chélation du Cd avec des ligands organiques de faible poids moléculaire. Alors qu'un ligand modèle comportant des groupes fonctionnels oxygène et azote (EDTA, R-OH, R-NH) n'a induit aucun fractionnement isotopique significatif entre le Cd 2+ complexé et le Cd 2+ libre (Δ 114/110 CdCdEDTA -Cd libre = -0,08 ± 0,12 ‰, n = 4), le ligand modèle avec des groupes donneurs de soufre (DMPS, R-SH) a induit un fort fractionnement isotopique (Δ 114/110 CdCdDMPS -Cd libre = -0,66 ± 0,20 ‰, n = 4). Ces résultats expérimentaux indiquent que la liaison du Cd aux thiols joue un rôle majeur dans la rétention des isotopes légers du Cd dans les racines et les pousses, minimisant ainsi leur transfert vers les grains céréaliers
Les besoins conflictuels optiques et mécaniques déterminent l'évolution de l'épaisseur de la membrane de l'aile chez les papillons transparents ithomiines
No full textTransparent animals are often thin, which raises the question of their fragility. In clearwing Lepidoptera, the wing thickness is the evolutionary result of conflicting optical and mechanical needs. All else being equal, a thinner membrane lets light better go through, can still sustain the reduced scales it often bears, it has a low stiffness advantageous for flight but it resists less to fatigue and failure, a crucial point. An evolutionary way out of these conflicting needs can be spatial heterogeneity in stiffness, with thicker opaque patches compensating for thinner transparent ones, especially when transparency covers a great wing surface proportion. We tested these predictions in Ithomiine butterflies, a tribe comprising closely-related opaque and transparent unpalatable species. We found that species with partially transparent wings have a thinner membrane in the transparent zone than in the opaque one, which likely helps light getting through and agrees with the lighter weight wings have to support in the transparent zone. Surprisingly, more transparent species have a thicker membrane in their transparent zone. We find no relationship between membrane thickness and scale density, ruling out a predominant role of membrane thickness as a mechanical support for scales. Finally, species with a higher wing proportion occupied by transparency have thicker membranes on their transparent patch, and a greater ratio in thickness between opaque and transparent zones. These latter two results support the hypothesis that clearwing butterflies with larger transparent patches are potentially more fragile and that this frailty is offset by thicker surrounding opaque patches offering higher mechanical resistance, like tubules framing a kite sail. In clearwing butterflies, wing membrane thickness has likely evolved under optical and mechanical selective pressures and further research should experimentally measure the costs, if any, of thinner transparent membranes.Les animaux transparents sont souvent minces, ce qui soulève la question de leur fragilité. Chez les Lépidoptères à ailes transparentes, l’épaisseur de l’aile est le résultat évolutif de besoins optiques et mécaniques contradictoires. Toutes choses égales par ailleurs, une membrane plus fine laisse mieux passer la lumière, et peut pourtant supporter les écailles réduites qu’on trouve souvent dans les zones transparentes. Elle présente une faible rigidité avantageuse pour le vol, mais résiste moins bien mécaniquement à la rupture, un point crucial. Une solution évolutive à ces contraintes opposées peut passer par une hétérogénéité spatiale de la rigidité, avec des zones opaques plus épaisses compensant les zones transparentes plus fines, en particulier lorsque la transparence occupe une grande proportion de la surface alaire.Nous avons testé ces prédictions chez les papillons ithomiines, une tribu comprenant des espèces toxiques étroitement apparentées, à ailes opaques ou transparentes. Nous avons constaté que les espèces partiellement transparentes possèdent une membrane plus fine en zone transparente qu’en zone opaque, ce qui favorise le passage de la lumière et peut quand même soutenir la masse plus faible que les ailes doivent supporter en zone transparente. De manière surprenante, les espèces les plus transparentes présentent une membrane plus épaisse dans leur zone transparente. Nous ne trouvons aucune relation entre l’épaisseur de la membrane et la densité des écailles, ce qui exclut un rôle prédominant de l’épaisseur membranaire comme support mécanique des écailles.Enfin, les espèces dont une plus grande proportion de l’aile est occupée par des zones transparentes présentent des membranes plus épaisses en zone transparente, et un ratio d’épaisseur plus élevé entre les zones opaques et transparentes. Ces deux derniers résultats soutiennent l’hypothèse selon laquelle les papillons à ailes transparentes dotés de larges zones transparentes sont potentiellement plus fragiles, et que cette fragilité est compensée par des zones opaques environnantes plus épaisses, offrant une plus grande résistance mécanique, à la manière de tubulures encadrant la voile d’un cerf-volant. Chez les papillons à ailes transparentes, l’épaisseur de la membrane alaire a probablement évolué sous l’effet de pressions de sélection à la fois optiques et mécaniques, et des recherches futures devraient mesurer expérimentalement les coûts éventuels de membranes transparentes plus fines
