eKhSACIR інституційному репозитарії Харківської державної академії культури
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<em>Clostridium difficile</em> is able to form a heterogeneous biofilm
No full textPrésentation orale - sélection sur résuméNational audienceClostridium difficile is a major entero-pathogen whose ability to form biofilms might be involved in colonization. An original system for biofilm growth in continuous-flow glass micro-fermentors was set up under anaerobiosis. A model virulent strain formed submersed macro-colonies and biofilms. According to a genome-wide analysis of gene expression, in biofilm/planktonic cells, sugar uptake, glycolysis and pyruvate conversion are favored over fermentations, and butyrate fermentation was confirmed to be reduced by CPG. Surface properties seem to be modified through active pathways: i) Type IV pilus biogenesis (e. g. Pil machinery and PilA1 pilin) and the synthesis of a few surface adhesins (e. g. CD2831). One c-di-GMP synthase, DccA, known to positively regulate both biofilm formation and CD2831 and PilA1 production, is produced at a high level in biofilm. pilA1 and CD2831 genes were found to be dispensable for biofilm formation in micro-fermentors. The biofilm architecture was then examined by confocal microscopy. The WT biofilm is high, sparse and heterogeneously composed of at least two cell populations: i) long and thin rods, filaments or chains, and ii) large aggregates. A strain over-expressing dccA formed more of a completely different, homogeneous biofilm, characterized by a unique population of very tightly packed cells, probably contiguous aggregates. Some role for pilA1 on biofilm formation morphology could be evidenced in the context of dccA over-expression, highly suggesting that Type IV pilin PilA1 could participate in cell aggregation in the homogenous biofilm. Finally, all our results show for the first time that C. difficile is able to form an original biofilm characterized by an extensive reprogramming of cell metabolism and surface properties, and by heterogeneity of cell morphologies. This is the first report that C. difficile can form a heterogenous biofilm
Modélisation intégrée du devenir des pesticides dans les paysages agricoles
No full textL'utilisation des pesticides en agriculture entraîne une contamination de la plupart des compartiments des écosystèmes (sol, eau, air) comme en témoignent les différents monitoring mis en place. Pour estimer le risque de contamination de ces compartiments et identifier les moyens de limiter cette contamination, il est nécessaire de développer une approche de modélisation qui décrive complètement les dynamiques et les voies de transfert des pesticides depuis l'échelle de la parcelle jusqu'à l'échelle du paysage, intégrant l'ensemble des compartiments. Jusque-là, le plus souvent, les approches de modélisation sont partielles car se focalisant chacune sur des dynamiques et compartiments spécifiques comme la dispersion atmosphérique d'une part, le transport par ruissellement de surface d'autre part ou encore la percolation vers les nappes souterraines. Cette communication présente un projet collaboratif pour la modélisation du devenir des pesticides qui rassemble six unités de recherche, soit une vingtaine de chercheurs et ingénieurs, pour développer un modèle intégré du devenir des pesticides à l'échelle du paysage. Ce modèle intégré permettra de prédire les concentrations en pesticides dans le sol, l'eau et l'air ainsi que les échanges dans et entre les différents compartiments sous l'influence conjointe de l'organisation spatio-temporelle des paysages et des pratiques agricoles à l'échelle d'un bassin versant. Le principe fondamental de cette démarche collaborative n'est pas de développer un nouveau modèle mais de réutiliser les approches de modélisation déjà développées dans chaque groupe de recherche et de les coupler via des plateformes de modélisation et simulation conçues pour faciliter la modélisation des agroenvironnements (plateformes OpenFLUID, SolVirtuel et RECORD). Cette communication présente alors les principes de la modélisation intégrée des pesticides à l'échelle du paysage qui est actuellement en cours de développement, et plus particulièrement les choix retenus pour i) la représentation spatiale des paysages agricoles (objets spatiaux, propriétés et connectivité spatiale), ii) les principaux processus considérés (distribution entre sol, culture et atmosphère ; transferts dans le sol et à la surface ; équilibres physico-chimiques ; émission vers l'atmosphère par volatilisation et dérive ; dispersion atmosphérique de la fraction volatile ; déposition gazeuse ; …) et iii) leur couplage spatio-temporel. Un des enjeux clés est de réussir le couplage à l'échelle du paysage de la modélisation de la dispersion atmosphérique avec la modélisation mise en oeuvre pour la modélisation des processus hydrologiques, et de représenter les échanges à l'interface surface/atmosphère à cette échelle. Les premiers résultats obtenus sur un bassin-versant viticole seront présentés
Extracellular vesicles from early pregnant uterine fluids promote expression of implantation-related markers in ovine endometrium
No full textTheme: Early Development and PregnancyTheme: Early Development and PregnancyExtracellular vesicles (EVs) are crucial for intercellular communications and they may play important role in the delivery of molecular messages during the pre-implantation period of pregnancy. EVs have been isolated from uterine luminal fluid (ULF) in human and sheep. Recent data have provided evidence that EVs contained in ovine ULF can penetrate endometrial epithelial cells after a 6-days infusion in vivo. Nevertheless, embryo implantation involves rapid and dynamic changes in molecular interactions with the endometrium. Our present work aims to determine whether EVs collected from ULF interact with endometrial epithelial cells and modify cell physiology after a short time of in vitro and in vivo incubation conditions.Primary cultures of endometrial epithelial cells were derived from ovine uteri on day 12 post-oestrus. EVs were purified from ovine ULFs on Day 14 of pregnancy (2 days before conceptus implantation). The presence of EVs in ULF was confirmed by transmission electron microscopic observation. ULF EVs were labeled with lipophilic PKH26 fluorescent dye and then incubated with primary cultures of epithelial cells during 30 min to 24h. Confocal microscopy analyses revealed an uptake of EVs as early as 30 minutes after incubation, followed by a progressive increase of intracellular fluorescence up to 6 hours.For the in vivo study, ovine ULF EVs isolated on Day 14 of pregnancy were labeled with PKH26 fluorescent dye and infused into the uterine lumen of cyclic ewes on Day 12 post-oestrus. After 24h, numerous epithelial cells from the luminal layer and superficial glands exhibited an intensive fluorescence signal, whereas deep endometrial glands displayed few fluorescent cells. No signal was detectable in the stroma. The impact of EVs on endometrial function was investigated by quantifying transcript expression of a selection of endometrial genes. First data pointed out that expression of two genes, including the Myxovirus-Resistance Protein (MX1) was up-regulated following EVs uptake by the endometrial epithelium. This work provides first evidence that ovine EVs from pregnant ULF can (i) enter in endometrial epithelial cells within 30 min in vitro or 24h in vivo (ii) modulate expression of endometrial gene expression known to be critical for embryo implantation. These results suggest a critical role for EVs in the preparation of endometrium when implantation iniates
4 D (x, y, z, t) imaging of digestive lipases during simulated neonatal gastro-intestinal digestion of milk fat globules or biomimetic emulsions using synchrotron SOLEIL DISCO beamline
No full textInternational audienceIn their native state, milk lipids are present in the form of dispersed droplets called Milk Fat Globules (MFG, average diameter of 4 µm in human and bovine milks), which have been recently pointed out as key elements of early nutritional programming. Understanding the specific digestive fate of MFG is thus a priority in neonatal nutrition. The MFG are unique biophysical elements differing from other lipoproteic objects by their external trilayered membrane inherited from their secretory past. To play their major biological function, i.e. deliver energy to the newborn, the MFG have to be hydrolyzed in the gastro-intestinal tract by lipases. This hydrolysis is typically a heterogeneous phase reaction, in which the lipase has to diffuse and get adsorbed onto the lipid phase before the formation of the enzyme-substrate complex, and the onset of the proper catalytic action. Very few techniques allow assessing the mechanisms involved in the enzymatic hydrolysis of complex supramolecular substrates such as MFG. To get a better insight of these mechanisms, 4-D imaging of gastric and pancreatic lipases enzymes using synchrotron SOLEIL UV fluorescence microscopy was applied during simulated static in vitro newborn digestion. This methodology allowed mapping the adsorption and diffusion of lipases onto/within human or bovine MFG or biomimetic droplets devoid of membrane proteins. These data were completed with simultaneous transmission light imaging of MFG disintegration during hydrolysis. The high sensitivity of the DISCO beamline allowing the detection of digestive lipases auto-fluorescence, is a unique tool to unravel their mechanisms of adsorption onto complex substrate using free-label imaging and has generated useful data for infant formula optimization
Effet d’extraits de cannelle et de marc de raisin riches en polyphénols sur le métabolisme, le microbiote intestinal et la barrière intestinale de la souris
No full textNational audienc
Phylogenetic Insights into the History of Tunisian and Iberian Cattle Using the Illumina BovineSNP50 BeadChip
No full textInternational audienceIn the present study, we used medium density SNP chips and comparisons with worldwide cattle to explore the phylogenetic history of Tunisian and Iberian cattle. We have pointed out an admixed origin of Tunisian populations and low African taurine proportions in the Iberian cattle genome. Our results suggest that iberian and Tunisian cattle derived from different origins and that a past admixture occurred between the
The new standards of economics applied to animal health - first results of a French research network
No full textInternational audienceEconomics of animal health (EAH) is of high interest for stakeholders and decision makers in agriculture (see NEAT project). Up to now, efforts in this growing scientific domain emerged form scattered initiatives, with a weak coordination between the society questions and the research developments, and also between the various research sciences involved. To improve this, an interdisciplinary research network entitled Economic reasoning for improved animal health was created in 2016 by INRA to help co-build a shared and interdisciplinary vision of EAH. This ongoing network is organized around regular workshops, open to researchers and representatives of the sectors. First findings and outcomes are reported here. First discussions revealed a high heterogeneity of stakeholders demand, including disease cost approaches and better understanding of actor behaviors. They also highlighted the need for promoting mutual understanding between scientific domains on the basis of existing advances in economics. This point serves as red line for the following sessions. The first workshop dealt with concepts in economics of production. This field was considered to be founder for EAH and to provide huge improvements for the understanding of the dynamics in the production decisions, including the determinants and consequences of health disorders and decisions. The economics of production is seen as of interest for questions around animal health ranging from farm level to chain level, providing answers for disease costs, best strategies to be retained and assessment of financial incentives for animal health management. Environmental economics is at the core of the 2nd workshop. This domain can be applied to externalities such as (i) antimicrobial use in animal production and (ii) strategic behaviors in the case of infectious diseases when private actions are dependent on neighborhood decisions. The 3rd topic is planned to focus on parallels with the economics of human health
Multi-objective evolutionary algorithms for influence maximization in social networks
No full textInternational audienceAs the pervasiveness of social networks increases, new NP-hard related problems become interesting for the optimization community. The objective of influence maximization is to contact the largest possible number of nodes in a network, starting from a small set of seed nodes, and assuming a model for information propagation. This problem is of utmost practical importance for applications ranging from social studies to marketing. The influence maximization problem is typically formulated assuming that the number of the seed nodes is a parameter. Differently, in this paper, we choose to formulate it in a multi-objective fashion, considering the minimization of the number of seed nodes among the goals, and we tackle it with an evolutionary approach. As a result, we are able to identify sets of seed nodes of different size that spread influence the best, providing factual data to trade-off costs with quality of the result. The methodology is tested on two real-world case studies, using two different influence propagation models, and compared against state-of-the-art heuristic algorithms. The results show that the proposed approach is almost always able to outperform the heuristics
