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Microscopie OPTIR : application à la microspectroscopie des microorganismes.
No full textInternational audienceLa spectroscopie OPTIR (Optical PhotoThermal InfraRed spectroscopy) est une technique de spectroscopie vibrationnelle utilisant un laser à cascade quantique (QCL) moyen-IR accordable qui induit un effet photothermique à la surface de l’échantillon, lorsque la longueur d'onde IR correspond à l’énergie d’un mode de vibration. Cet effet photothermique est mesuré à l'aide d'un laser de sonde, de longueur d’onde dans le visible, focalisé à la surface de l'échantillon [1]. Il s’agit d’une technologie qui permet des mesures de spectroscopie IR ainsi que la réalisation d'images chimiques d'absorption infrarouge, avec une résolution spatiale submicronique identique à celle de l'imagerie photonique et indépendante de la longueur d'onde d’absorption. L'OPTIR offre ainsi une mesure d'absorption IR de qualité, sans contact avec la surface. Adossé à l’UMR PAM, le site imagerie spectroscopique de la plateforme Dimacell met à disposition de la communauté scientifique un microscope basé sur cette technologie avec un équipement permettant également de faire une analyse Raman en simultané et en développe les applications dans le domaine de la microbiologie. L’objectif de cette présentation est de présenter en détails la mise en œuvre de cette technique d'imagerie spectroscopique émergente et de ses potentialités, ainsi que son application pour la caractérisation et l’identification de microorganismes (bactéries, levures, spores)
Être étudiant à l'ère de l'intelligence artificielle générative : renseigner et comprendre les usages d'étudiants en formation d'ingénieurs
No full textInternational audienc
Monitoring of lipid oxidation using a fluorescent sol-gel functionalized material
No full textInternational audienceThe food industry lacks rapid, easy-to-use and non-toxic analytical methods to assess the oxidation level of lipid-rich products. A new fluorescent sol-gel sensing material was developed for the fast and simple monitoring of carbonyls secondary products of lipid oxidation. This paper defines the sensor's range of applicability, specifically examining the impact of the nature and structure of the detected carbonyl compounds, as well as the effects of pH and the nature of the food-simulating medium on its response. The material exhibited high fluorescence intensity, which was quenched upon interaction with carbonyls. The size and hydrophobicity of the analyte (propanal, hexanal, nonanal, 1-penten-3-one and 1-octen-3-one) impacted the kinetics and the percentage of fluorescence quenching as well as the limit of detection and the saturation limit of the sensor. Additionally, the solvent nature had a significant impact on fluorescence: fluorescence intensity was higher in ethanol compared to the more polar ethanol/water (10/90, v/v) mixture used as a food simulant. Finally, the optimal pH range to operate the sensor was determined to be from 7 to 9. This study thus validated the feasibility of using this new sensor for the fast (less than 5 min) and simple (no sample preparation) monitoring of food oxidation level without using any toxic reagent compared to conventional methods. The sensor enables global carbonyl content determination within an operative pH range and a range of detection that would cover the entire shelf-life of lipid-rich food products
Avis relatif à la détermination de la VMAX dans les EDCH pour le métabolite de pesticide 1,2,4-triazole et les substances actives chlordécone et glyphosate
No full textAnses. (2025). Avis de l’Anses relatif à la détermination de valeurs sanitaires maximales (VMAX), pour le métabolite de pesticide 1,2,4-triazole et les substances actives chlordécone et glyphosate, dans les eaux destinées à la consommation humaine (EDCH). (saisine 2023-SA0041-c). Maisons-Alfort : Anses, 21 p.CONTEXTE ET OBJET DE LA SAISINEPour garantir la qualité des EDCH, la Directive (UE) 2020/2184 [1], transposée en droit français, fixe des valeurs paramétriques pour les concentrations en pesticides et leurs métabolites pertinents (0,1 µg.L-1 par substance individuelle [2] et 0,5 µg.L-1 pour la somme des pesticides et de leurs métabolites pertinents), sans définir les critères ou les modalités d’évaluation de cette pertinence. L’arrêté du 11 janvier 2007 modifié [3] reprend ces valeurs en tant que limites de qualité (LQ) dans les EDCH pour les pesticides et leurs métabolites pertinents.À la demande de la Direction générale de la santé (DGS), l’Anses a proposé en janvier 2019 (Anses, 2019a) une méthodologie permettant l’évaluation de la pertinence des métabolites de pesticides dans les EDCH au vu des connaissances scientifiques disponibles. Elle est destinée à être mise en œuvre dans le cadre d’une expertise collective de l’Anses, en s’appuyant sur les données disponibles (principalement issues des dossiers de demande d’approbation des substances actives et de la littérature scientifique à disposition). Sur la base du résultat d’une telle évaluation, et de tout autre élément qu’elle considérerait approprié, la DGS désigne les métabolites pertinents et fixe les modalités de leur surveillance. En l’absence d’évaluation, un métabolite est considéré comme pertinent par défaut.En situation de dépassement d’une LQ, la réglementation française prévoit un dispositif dérogatoire et gradué de gestion du risque. La LQ de 0,1 µg.L-1 pour les pesticides et les métabolites pertinents ne reposant pas sur des fondements toxicologiques, le dispositif de gestion des risques liés à des dépassements de cette LQ s’appuie notamment depuis 2007 sur l’élaboration de valeurs sanitaires maximales (VMAX) proposées par l’Anses pour des SA de pesticides et des métabolites pertinents. La référence à ces VMAX a vocation à être utilisée pour une période limitée dans le temps d’une durée maximale de six ans pendant laquelle des actions de remédiation (amélioration de la qualité de l’eau de la ressource, mise en place de traitements pour l’EDCH, interconnexions, etc.) doivent être mises en œuvre.La méthode de détermination des VMAX de pesticides a été actualisée dans l’avis du 17 décembre 2019 (Anses, 2019b). La liste des VMAX de pesticides dans l’EDCH établies pour les SA ou les métabolites pertinents de pesticides est disponible sur le site de l’Agence [4].Dans la perspective de gestion sanitaire de situations de non-conformité (dépassement des LQ) vis-à-vis de pesticides et de métabolites de pesticides dans les EDCH relevées dans le cadre du contrôle sanitaire ou de la campagne nationale exploratoire menée par le Laboratoire d’hydrologie de Nancy (LHN) entre 2020 et 2022 (Anses, 2023), la DGS a saisi l’Anses le 15 février 2023 pour déterminer les VMAX pour 13 pesticides et métabolites de pesticides et, pour certains des métabolites, évaluer le classement de la pertinence au préalable. Ainsi, plusieurs livrables échelonnés dans le temps sont prévus en réponse à cette saisine. Les VMAX déjà déterminées dans le cadre de cette saisine ont fait l’objet d’un avis du 25 juillet 2024 (Anses, 2024).Le présent avis concerne la détermination de VMAX pour les substances actives chlordécone et glyphosate ainsi que pour le métabolite 1,2,4-triazole. [1] Directive (UE) 2020/2184 du Parlement européen et du Conseil du 16 décembre 2020 relative à la qualité des eaux destinées à la consommation humaine[2] À l’exception de l’aldrine, dieldrine, heptachlore et heptachlore époxyde pour lesquels la valeur est de 0,03 µg.L-1[3] Arrêté du 11 janvier 2007 relatif aux limites et références de qualité des eaux brutes et des eaux destinées à la consommation humaine mentionnées aux articles R. 1321-2, R. 1321-3, R. 1321-7 et R. 1321-38 du code de la santé publique[4] Consulter la page Internet consacrée aux travaux de l’Anses sur les pesticides dans les EDCH et en particulier le tableau recensant les VMAX établies par l’Anses : https://www.anses.fr/fr/content/detecter-et-surveiller-les-pesticides-dans-leau-du-robine
Microbial transfers in dairy systems under changing climate and farming practices
No full textInternational audienceEvolving agricultural practices aimed at mitigating the effects of climate change raise questions about their impact on the microbial characteristics of the food matrix, which is particularly relevant for raw milk cheese production. To address these issues, we explored microbial transfers across cheese production from farm environments to raw milk cheese and rat microbiota consuming these cheeses in four farming systems with varying grazing proportions in cow diet for 3 months. 736 samples were collected in 12 ecosystems (air, soil, grass, cow rumen and feces, teats, bedding material, milk, milk filter, cheese curd and rind, and rat feces) and at three sampling dates (only one for cheeses and rats). The bacterial and fungal communities were characterized by 16S V3-V4 and ITS sequencing and data were processed with rAnomaly package [1] (dada2 [2], taxonomic assignation 16S: SILVA database and DairyDB, ITS: UNITE and UTOPIA).We first describe the twelve ecosystems in terms of community composition and diversity and analyze the impact of farming systems and sampling date on ecosystem diversity. We then focus on microbial transfers between ecosystems, identify shared ASVs across the farm to fork agri-food chain, and determine diversity hotspots and bottlenecks impacting downstream microbiota, such as bedding material or cow rumens. We finally study how the microbial transfers differ between the four farming systems and evolve in time.</p
Ultra-processed foods are of poor nutritional quality in French consumers' representations; a categorization study of images of food products without information
No full textInternational audienceThis study investigated how consumers categorize food according to its nutritional quality and degree of processing through two online questionnaires. Two hundred French consumers used a directed sorting task to categorize 21 images of food products by nutritional quality and degree of processing. The images contained no information about these two characteristics or any other properties. Two multinomial logit regression analyses revealed that (1) without any access to established values for degree of processing or nutritional quality, participants' categorizations of food images closely mirrored these established values; (2) participants' categorization of food products by nutritional quality was also influenced by non-nutritional properties; (3) participants linked nutritional quality to degree of processing in their categorizations. Possible reasons are proposed for this link and the cognitive mechanisms involved, such as a learned association resulting from the overly simple messages conveyed by dietary guidelines, the use of heuristics to overcome the difficulty of estimating the nutritional quality of food products in the absence of information, and the health halo effect
How to conciliate nutritional and environmental targets of adult diet in France while halving current meat consumption?
No full textInternational audienceTo contribute to the ecological transition, several scenarios recommend reducing by 50% or more the current meat consumption in France. The aim of the present study was to identify which minimum dietary changes would be necessary, in addition to halving meat consumption (including poultry and deli meat), to reduce the carbon impact of diet (CI-d) without worsening other environmental impacts, while satisfying a set of nutrient intake recommendations (nutritional adequacy). Based on the average consumption of adults from the INCA3 survey, 10 diets were modeled under different assumptions. The results show that it is possible to achieve nutritional adequacy with 2 times less meat than today (62g/d vs. 124g/d), without supplements or fortified foods, while significantly reducing CI-d (by up to 50%). The modeled diet that was the closest to current consumption, which had CI-d reduced by 35%, contained meat (excluding deli meat), fish or eggs around 1 time per day, 3 dairy products per day, an abundance of minimally processed and unrefined plant-based foods (70% of solid weight, including 65g/d of pulses and 30g/d of nuts), 2.5 times fewer fatty, sweet and/or salty products. Such a diet, that conciliates nutritional and environmental targets, would also cost less (10% cost reduction)
Pathogen-induced root glutamine concentration is a determinant of the outcome of the Medicago truncatula-Aphanomyces euteiches interaction
No full textData : Metabolomics data are included in the supplementary files. RNAseq data are available at the National Center for Biotechnology Information (NCBI) | Gene Expression Omnibus (GEO) (https://www.ncbi.nlm.nih.gov/geo/) under accession number [GEO: GSE281426].International audienceMain conclusion. Our work highlights that glutamine plays a central role in contributing to the outcome of disease in the Medicago truncatula-Aphanomyces euteiches interaction when modulating plant N supply.Abstract. Nitrogen (N) is essential for the growth of plants and microorganisms. The quantity and quality of N supply can impact plant development but also its interaction with pathogens. Our previous work showed that N modulated Medicago truncatula (Mt) susceptibility to the oomycete pathogen Aphanomyces euteiches (Ae) when plants were grown in vitro and glutamine (Gln) was proposed to mediate this effect of N on plant disease. Using more than 30 lines representative of Mt diversity, we show here that pathogen-induced root Gln concentrations are correlated with higher susceptibility to Ae. N modulation of the response to Ae of the partially resistant Mt A17 genotype was associated with changes in the expression of MtGS1 genes encoding cytosolic glutamine synthetases (GSs). This raises the question of the importance of Gln during Mt/Ae interaction and a possible role of cytosolic GS in mediating Mt susceptibility to Ae. Interestingly, exogenous Gln induced a higher susceptibility of the A17 line to Ae and induced a metabolic profile of inoculated A17 roots similar to that of a susceptible genotype. RNAseq experiments highlighted a higher expression of numerous plant defense genes in non-inoculated roots on Gln. On the pathogen side, a higher expression of genes encoding proteases and a lower expression of genes encoding elicitins as well as a better growth of Ae on Gln could explain the higher susceptibility of Mt on Gln. Altogether our results highlight the delicate balance between plant immunity, pathogen growth and virulence in contributing to the outcome of disease when modulating N supply and that Gln plays a central role in this process
Can MDS rival with t-SNE by using the symmetric Kullback-Leibler divergence across neighborhoods as a pseudo-distance?
No full textInternational audienceLocal methods of dimensionality reduction like neighborhood embedding (NE) and t-SNE in particular outperform older global approaches such as stress-based multi-dimensional scaling (MDS). Stochastic neighborhoods are less sensitive than distances to statistical variations between spaces with strongly different dimensionalities, making a match across them very difficult. Here, we take inspiration from those stochastic neighborhoods in order to devise a pseudo-distance that is less prone to concentration than the Euclidean distance. For two points in the high-dimensional data space, it is defined as the symmetrized Kullback-Leibler divergence across the (stochastic) neighborhoods of the two points (SKLAN). Plugging the SKLAN in a method of stress-based MDS, we compare quantitatively t-SNE, MDS with all Euclidean distances, and MDS with SKLAN & Euclidean distances on several data sets. The results show that SKLAN allows MDS to perform competitively with t-SNE
Assessing crop water deficiency for regional adaptation to climate change
No full textInternational audienceThe increase in crop water stress is one of the most critical effects of climate change and threatens farm production and food security both locally and globally. The adaptation process of the entire food system must be grounded in a local quantitative assessment of future water requirements and the consequences for production losses if those requirements are not met. Thus, we developed a high-resolution crop water requirement model which integrates climate, soil and crop characteristics at a daily timestep. Our prospective study for 2100 (using the RCP8.5 climate scenario) at the regional scale (Bourgogne–Franche–Comté, BFC, in Eastern France) reveals a projected 8 % decrease in average grain production and a 14 % reduction in forage production. However, crop response to climate change vary both spatially and temporally. Summer crops are expected to bear a more marked impact from water stress, with an increase in variability over the years, amplifying the risk for human and animal food security. Other aspects of climate change, such as heat stress, late-spring frost, or an increase in pest pressure, could further impact yields. We emphasize the necessity of addressing climate change adaptation at the regional system level through multi-actor collaboration. Our reproducible approach serves as a rational starting point for designing new strategies based on a combination of adaptive responses at different scales, spanning from the field to the regional scale