Portail HAL Um (Université de Montpellier)
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Bulletin de veille du réseau d'écotoxicologie terrestre et aquatique N°83
No full textINRAE, réseau ECOTOX → A paraîtreBulletin de veill
Bulletin de veille du réseau d'écotoxicologie terrestre et aquatique N°79
No full textINRAE, réseau ECOTOX → A paraîtreBulletin de veill
Interacting drivers of Holocene climate change in southwestern Africa: the influence of insolation, rainbelt dynamics and upwelling
No full textInternational audienceUnderstanding regional-scale patterns of long-term climate variability is essential for identifying the drivers of past environmental change. In southern Africa, the continent is often divided into three rainfall zones-summer, winter, and aseasonal-but this framework fails to capture the finer dynamics of transitional areas where tropical, subtropical, and temperate systems converge. This study examines Holocene climate variability along the western margin of the southern African monsoon region using a new 7300-year nitrogen isotope record from rock hyrax middens at Omanyne-4 in northern Namibia. Unlike other Namib Desert records that indicate progressive aridification through the Holocene, the Omanyne-4 sequence shows a long-term trend toward increasing humidity, consistent with insolation-driven enhancement of tropical and Indian Ocean moisture advection. Comparisons with records from northern Namibia, Botswana, and western Zambia reveal a coherent pattern of mid-to late Holocene humidification across the northwestern interior, in contrast to coastal aridification. Periods of both in-phase and antiphase variability with other regional records highlight the role of the Angola-Benguela Front and associated upwelling dynamics in modulating Namibian hydroclimate. These results delineate distinct Holocene climate response regions in northern Namibia and Botswana and demonstrate the non-linear nature of regional responses to insolation forcing and underscore the importance of coastal-inland atmospheric interactions in shaping long-term hydroclimate variability in southwestern Africa.</div
Mineralogical constraints on carbon deportment in phosphate ores: Implications for decarbonizing ore processing
No full textInternational audienceThe release of CO2 from carbon-bearing minerals during phosphate ore processing contributes to industrial emissions but remains poorly quantified. This study examines the Bouchane phosphate deposit, part of the Gantour Basin in Morocco, which consists of Upper Cretaceous–Paleogene sedimentary phosphates. The objective is to constrain the proportions and deportment of carbon within its mineral phases and assess their contribution to CO2 release during beneficiation and acidulation. For this purpose, 20 representative samples from a stratigraphic section of the deposit were analyzed for petrographic composition, bulk mineralogy by X-ray diffraction, bulk geochemistry by inductively coupled plasma optical emission spectroscopy (ICP-OES), and total carbon by induction furnace, complemented by in-situ microanalyses using an electron probe micro-analyzer (EPMA) and quantitative automated mineralogy with a TESCAN Integrated Mineral Analyzer (TIMA). Moreover, the modal composition of the studied samples was determined using various approaches such as quantitative X-ray diffraction (QXRD), quantitative automated mineralogy (QAM), element-to-mineral conversion (EMC), and total inversion (TI). The studied samples were predominantly composed of phosphatic coated grains, peloids, coprolites, and skeletal particles. The chemistry of these sediments varied along the stratigraphic section, marked by a dominance of inorganic carbon compared to organic carbon, with a mean content of 11.38 ± 4.58 wt% and 0.68 ± 0.03 wt%, respectively. The developed calculated mineralogy techniques (EMC, TI) proved successful in accurate quantification of the modal composition of the phosphate sediments. Automated mineralogy by TIMA provided a quantification of the percentage of problematic locked carbonates within phosphatic grains, with values below 3 %. These grains were predicted to hold 11 % of the CO2 in carbonate fluorapatite (CFA), and 0.3 % and 0.1 % in calcite and dolomite, respectively. The remaining carbonate phases are removed during washing and flotation. This study shows that adopting holistic approaches in phosphate mining is efficient for developing rapid, low-cost techniques for mineralogical characterization (EMC, TI) and indicates that phosphate rock processing results in limited in situ CO2 release from carbonate minerals
Structure and dynamics of a precarious entrepreneurial sub-ecosystem in a developed country
No full textInternational audienceEntrepreneurial ecosystem research increasingly recognizes the importance of sub-ecosystems, yet their dynamics in contexts of precarity remain underexplored. This article introduces the concept of precarious entrepreneurial sub-ecosystems and examines how entrepreneurship unfolds under conditions of resource scarcity and social vulnerability in Montpellier, France. By mobilizing a complex adaptive systems perspective, we develop a multilevel model of a entrepreneurial sub-ecosystem. The analysis shows how such sub-ecosystems build solidarity-based coordination and navigate spatial, social and institutional boundaries to support precarious entrepreneurs. In doing so, the study extends entrepreneurial ecosystem theory to more fragile settings and refines the sub-ecosystem construct as a nested, adaptive, context-dependent system. It shows that even in constrained, marginalized contexts, entrepreneurial activity can be sustained through continuous adaptation, resource mobilization, and inclusive institutional frameworks
Biofouling in milli-labyrinth channels of drip irrigation systems using reclaimed wastewater: A review of optical methods and numerical modelling
No full textInternational audienceDrip irrigation systems are known for their high water-use efficiency due to the combination of using milli-labyrinth channels to optimise flow distribution and reusing reclaimed wastewater. However, clogging andbiofouling remain significant challenges that affect system performance and lifespan. This review provides acomprehensive overview of biofouling in drip irrigation systems, with a focus on how hydrodynamic conditionsand nutrient availability in reclaimed wastewater influence the attachment, growth, detachment, and decayof biofilm. The ability of advanced optical techniques, including particle tracking velocimetry, industrialcomputed tomography, and optical coherence tomography to visualise, measure, and analyse biofoulingprocesses in drip irrigation systems is discussed, along with their strengths and limitations. Additionally, theability of current biofilm modelling approaches, including both continuum and discrete methods, to simulatenutrient transport, microbial activity, and biofilm–fluid interactions are discussed. By combining insights fromexperimental data and computational models, this review also identifies key research gaps and presents a newframework for applying biofilm modelling to drip irrigation systems. Future research directions are suggestedto improve our understanding of drip irrigation biofouling and to predict it, to optimise emitter design, andincrease the overall reliability and sustainability of drip irrigation system
Morphological variation and genetic diversity of breadfruit [Artocarpus altilis (Parkinson) Fosberg] in Vanuatu
No full textSource Agritrop Cirad (https://agritrop.cirad.fr/616069/) * Autres projets (id;sigle;titre): 2271;;(FRA) Indications Géographiques pour le Pacifique// ;NAAP;(FRA) Nexus agriculture-alimentation dans le Pacifique insulaire//International audienceBreadfruit, Artocarpus altilis (Parkinson) Fosberg, is a versatile tree crop widely distributed in Oceania and tropical regions. It produces starchy fruits that contribute to food security in Pacific Island countries. In Vanuatu, where it is considered as a secondary food crop, a better understanding of the diversity of this species is a prerequisite for setting up a genetic improvement strategy. A diversity study of 123 accessions collected in 27 villages on eleven islands across Vanuatu and conserved in an ex-situ field gene bank was conducted in 2023–24. Eighteen morphological descriptors of fruits and leaves were utilized and genotyping was performed using 15 single sequence repeat (SSR) markers. The results showed that Vanuatu cultivars exhibit important morphological variation. Most of them (except two) are diploid and seeded. Analysis of SSR profiles revealed four genetic groups and 99 unique multilocus genotypes. Cultivars collected in the northern and north-central regions of Vanuatu appeared to be more genetically diverse than those collected further south. A total of 152 alleles were detected across the 15 loci, with an average number of 10.13 alleles per locus. For comparison, SSR analysis of triploid seedless cultivars from Eastern Polynesia and the Indian Ocean showed that these cultivars, although morphologically different, share a very narrow genetic base and are hardly distinguishable with the set of markers used in this study. These results confirm that Vanuatu is an important centre of breadfruit diversity and that this diversity is dynamic due to the diploid nature of cultivars with a high percentage of seed propagated trees
SpeckSeq enables high-throughput functional stratification of MEFV variants in autoinflammatory diseases
No full textInternational audienceVariants of uncertain significance (VUS) are a major obstacle in genetic diagnosis, particularly when involving gain-of-function (GoF) mutations that are poorly predicted in silico. MEFV, which encodes the inflammasome sensor pyrin, is mutated in two autoinflammatory diseases, familial Mediterranean fever (FMF) and pyrin-associated autoinflammation with neutrophilic dermatosis (PAAND). Here, we developed SpeckSeq, a method that combines DNA bar-coding, ASC speck–based single-cell sorting and next-generation sequencing to systematically identify hypermorphic MEFV variants in response to different stimuli. SpeckSeq identified 49 GoF mutations separated into two distinct groups containing either PAAND variants or FMF variants. SpeckSeq was validated using patients’ cells and supported a reclassification of MEFV variant pathogenicity, leading to novel diagnoses. As a large-scale mutagenesis approach, using human genetics as a guide, SpeckSeq revealed structural and functional pyrin features, including a putative ligand-accommodating cavity in the B30.2 domain. Altogether, SpeckSeq classifies VUS to refine molecular diagnostics and improve our knowledge on the pyrin inflammasome
A WAS promoter variant underlying Wiskott-Aldrich syndrome in two kindreds
No full textInternational audienceWe report the same ultra-rare pathogenic noncoding single-nucleotide variant in the promoter of WAS in four male patients from two unrelated kindreds with features of Wiskott-Aldrich syndrome
Crucial Role of Oxidation for the Prebiotic Peptide Elongation Promoted by Carbonyl Sulfide
No full textInternational audienceBoth the emergence and sustainability of dissipative chemical systems, such as protometabolisms, require a constant flow of free energy, which can, among other possibilities, be provided by chemical activating agents. Several prebiotically plausible candidates have been identified, but none are flawless or even sufficiently efficient to consider this question resolved. This study revisits and extends previous work on amino acid activation and peptide elongation promoted by carbonyl sulfide in aqueous medium which proceeds via the formation of N ‐carboxyanhydrides (NCAs). Through an approach aimed at providing new mechanistic insights, it demonstrates that oxidation of the thiocarbamate adduct is mandatory for subsequent NCA and peptide bond formation and that ferricyanide, as an oxidizing agent example, efficiently promotes the reaction even at mild pH. However, side reactions, such as urea/hydantoin formation, were confirmed to strongly limit the prebiotic scope of this N‐terminal peptide elongation route