Search results for "MICROORGANISME"
showing 10 items of 107 documents
Réponses des cellules de Nicotiana tabacum à des molécules microbiennes : évènements de signalisation précoce, influence de la dynamique membranaire …
2018
In their natural environment plants are in close interaction with beneficial, neutral, or pathogenic microbes, which are highly dependent on carbon resources exuded by plant roots. Sugar transport, which is a key process of plant physiology, is essential to support the fate of plant-microbe interactions. During evolution, plants have acquired the ability to perceive microbial molecules, initiating specific signal transduction cascades and leading to adapted response for microbe lifestyles (avirulent, virulent, or benefic). Plant survival will depend on the nature of the induced mechanisms. My PhD work, carried out on a simplified experimental system, contributes to the understanding of mech…
L’agroforesterie, le futur de la viticulture ?
2020
L’agroforesterie est l’association sur une même parcelle d’une végétation arborée et/ou arbustive, et d’une production végétale, animale ou mixte. Les espèces ligneuses peuvent être réparties uniformément, inégalement ou en bordure de parcelle. Les systèmes agroforestiers fournissent des services écosystémiques et des produits et ce à différentes échelles ; parcelle, exploitation agricole, unité paysagère » (RRAF, 2018). La productivité de ces systèmes dépend de la différence nette entre les avantages et les coûts, entre les utilisations et les composantes biophysiques de l’agroenvironnement. Dans les systèmes de cultures intercalaires, les avantages des arbres sont à la fois économiques et…
Direct seeding mulch-based cropping increases both the activity and the abundance of denitrifier communities in a tropical soil
2009
International audience; This study evaluated the impact of direct seeding mulch-based cropping (DMC), as an alternative to conventional tilling (CT), on a functional community involved in N cycling and emission of greenhouse gas nitrous oxide (N2O). The study was carried out for annual soybean/rice crop rotation in the Highlands of Madagascar. The differences between the two soil management strategies (direct seeding with mulched crop residues versus tillage without incorporation of crop residues) were studied along a fertilization gradient (no fertilizer, organic fertilizer, organic plus mineral fertilizers). The activity and size of the denitrifier community were determined by denitrifica…
Conservation of type III secretion system genes inBradyrhizobiumisolated from soybean
2006
International audience; The distribution of rhcRST genes encoding the type III secretion system (T3SS) in a collection of Bradyrhizobium strains was characterized by PCR and Southern blot hybridization. The polymorphism of the corresponding sequences amplified by PCR was characterized by RFLP and sequencing together with those available in the databank. Genomic group I is characterized by the presence of Bradyrhizobium elkanii strains and group II by the presence of B. japonicum and B. liaoningense strains. Highly conserved T3SS-like genes were detected by PCR in all Bradyrhizobium strains isolated from soybean belonging to genomic group II, and in none of the strains belonging to genomic g…
Identification of bacterial groups preferentially associated with mycorrhizal roots of Medicago truncatula
2007
ABSTRACT The genetic structures of bacterial communities associated with Medicago truncatula Gaertn. cv. Jemalong line J5 (Myc + Nod + ) and its symbiosis-defective mutants TRV48 (Myc + Nod − ) and TRV25 (Myc − Nod − ) were compared. Plants were cultivated in a fertile soil (Châteaurenard, France) and in soil from the Mediterranean basin showing a low fertility (Mas d'Imbert, France). Plant growth, root architecture, and the efficiency of root symbiosis of the three plant genotypes were characterized in the two soils. Structures of the bacterial communities were assessed by automated-ribosomal intergenic spacer analysis (A-RISA) fingerprinting from DNA extracted from the rhizosphere soil an…
La microbiologie moléculaire environnementale : historique, limites et potentialités
2017
prod 2017-237c INRA EA BIOmE; Résumé de la brochure : Dans une société où il devient urgent de réduire l'empreinte environnementale des activités humaines, la première étape est de pouvoir faire un diagnostic de la qualité de notre environnement et des différentes matrices le constituant (eau, sol, atmosphère, déchets). Les microorganismes, de par leur petite taille, leur énorme diversité taxonomique et génétique, leur réactivité aux perturbations ainsi que par leur forte implication dans les cycles biogéochimiques gérant les flux de matière et d'énergie, sont des candidats incontournables pour élaborer ce diagnostic. Ceci est d'autant plus vrai que depuis une vingtaine d'années les fortes …
Extracellular histones trigger oxidative stress-dependent induction of the NF-kB/CAM pathway via TLR4 in endothelial cells.
2022
Abstract Extracellular histones have been reported to aggravate different pathophysiological processes by increasing vascular permeability, coagulopathy, and inflammation. In the present study, we elucidate how extracellular histones (10–100 µg/mL) concentration dependently increase cytosolic reactive oxygen species (ROS) production using human umbilical vein endothelial cells (HUVECs). Furthermore, we identify cyclooxygenase (COX) and NADPH oxidase (NOX) activity as sources of ROS production in extracellular histone-treated HUVEC. This COX/NOX-mediated ROS production is also involved in enhanced NF-kB activity and cell adhesion molecules (VCAM1 and ICAM1) expression in histone-treated HUVE…
Optimising an outdoor membrane photobioreactor for tertiary sewage treatment
2019
[EN] The operation of an outdoor membrane photobioreactor plant which treated the effluent of an anaerobic membrane bioreactor was optimised. Biomass retention times of 4.5, 6, and 9 days were tested. At a biomass retention time of 4.5 days, maximum nitrogen recovery rate:light irradiance ratios, photosynthetic efficiencies and carbon biofixations of 51.7¿±¿14.3¿mg¿N·mol¿1, 4.4¿±¿1.6% and 0.50¿±¿0.05¿kg CO2·m3influent, respectively, were attained. Minimum membrane fouling rates were achieved when operating at the shortest biomass retention time because of the lower solid concentration and the negligible amount of cyanobacteria and protozoa. Hydraulic retention times of 3.5, 2, and 1.5 days …
Response of soil bacterial community structure to successive perturbations of different types and intensities
2008
SummaryIn soil, genetic structure modifications of indigenousbacterial community consecutively to a severe stress(mercury contamination) were delayed when thecommunity was pre-exposed to various minor per-turbations (heat, copper and atrazine). Such minorperturbations induced transitory community struc-ture modifications leading to an increase of commu-nity stability towards a severe mercury stress. Theseresults illustrated well the short-term pre-adaptationprocess for bacterial community hypothesizing thatcommunity submitted to perturbations become moreresistant to withstand another stress. Compared with other environmental matrices of the bio-sphere, soils are considered as the main reservo…
Effect of primary mild stresses on resilience and resistance of the nitrate reducer community to a subsequent severe stress
2008
International audience; The factors regulating soil microbial stability (e.g. resistance and resilience) are poorly understood, even though microorganisms are essential for ecosystem functioning. In this study, we tested whether a functional microbial community subjected to different primary mild stresses was equally resistant or resilient to a subsequent severe stress. The nitrate reducers were selected as model community and analysed in terms of nitrate reduction rates and genetic structure by narG PCR-restriction fragment length polymorphism fingerprinting. Heat, copper and atrazine were used as primary stresses and mercury at a high concentration as a severe stress. None of the primary …