Search results for "Reaction"
showing 10 items of 6134 documents
Medicago species affect the community composition of arbuscular mycorrhizal fungi associated with roots
2007
National audience; The symbiosis between plants and arbuscular mycorrhizal fungi (AMF) is ancient and involves 80% of terrestrial plant families. The symbiotic association between AMF and plants was described to be non specific. However, AMF were reported to influence plant community diversity and productivity. On the other way, the effect of plant genotypes belonging to closely related species on AMF diversity has not been explored so far. The aim of this work was to assess the impact of four different Medicago species, M. laciniata, M. murex, M. polymorpha and M. truncatula cv. Jemalong J5, on the composition of AM fungal community, when cultivated in a silty-thin clay soil (Mas d’Imbert,…
Relationships between Staphylococcus aureus genetic background, virulence factors, agr groups (alleles), and human disease
2002
ABSTRACT The expression of most Staphylococcus aureus virulence factors is controlled by the agr locus, which encodes a two-component signaling pathway whose activating ligand is an agr -encoded autoinducing peptide (AIP). A polymorphism in the amino acid sequence of the AIP and of its corresponding receptor divides S. aureus strains into four major groups. Within a given group, each strain produces a peptide that can activate the agr response in the other member strains, whereas the AIPs belonging to different groups are usually mutually inhibitory. We investigated a possible relationship between agr groups and human S. aureus disease by studying 198 S. aureus strains isolated from 14 asym…
Dynamiques de populations en milieu hétérogène : modèles et estimation de paramètres
2017
Prod 2017-344i SPE équipe EA GESTAD INRA; National audience; Cet exposé traite de (i) la modélisation de dynamiques de populations dans des paysages hétérogènes, (ii) la modélisation des paysages eux-mêmes, (iii) l'estimation des paramètres de ces modèles à partir de données d'abondance ou de données génétiques. Nous nous concentrerons sur deux grandes classes de modèles de dynamique des populations : les modèles individu-centrés basés sur des équations différentielles stochastiques, et les modèles de réaction-diffusion. Après une introduction du lien entre ces approches, 5 illustrations issues des projets sont présentées: - modélisation de paysages hétérogènes fragmentés, via l’outil MULTI…
PTR-SRI-ToF-MS analysis of aroma compounds: influence of drift tube E/N ratio on sensitivity and fragmentattion
2013
Livre ISBN-13 : 978-3-902811-91-2; International audience; The aim of this work was to compare detection and fragmentation patterns of aroma compounds obtained with three different precursor ions and several E/N source parameter values with the proton transfer reaction (PTR-MS) methodology. The reactant ions H3O+, NO+ and O2+. were generated in a Switchable Reagent Ions (SRI) source of a PTR-ToF-MS (Ionicon 8000, Innsbruck, Austria). Precursor ions plasmas were characterized at different E/N ratio in the drift tube. For proton transfer reaction, the hydronium primary ion was the most abundant ion (> 80%) for all E/N ratios above 120 Td, but the sensitivity decreased quickly with the highest…
In vivo aroma release by APCI-MS and PTR-MS: impact of water content of exhaled air and evidence for competition between aroma compounds
2013
Livre ISBN-13 : 978-3-902811-91-2; International audience; Atmospheric pressure chemical ionization mass spectrometry (APCI-MS) or proton transfer reaction mass spectrometry (PTR-MS) has been in use frequently for in vivo aroma release studies. In APCI-MS, protonated water clusters formed from moisture in the expired air are used as reagent ions. Yet the influence of a change in relative water content in the ionization gas on the data collected have been rarely studied and conflicting results were obtained. In this context our first objective was to study the impact of water content of the expired air on the level of aroma release measured by APCI-MS and to compare with the results obtained…
Structure-function analysis of peroxisomal ATP-binding cassette transporters using chimeric dimers
2014
Background: Peroxisomal ABC transporters are predicted to function as homodimers in mammals. [br/] Results: ABCD1 interacts with ABCD2. Chimeric proteins mimicking full-length dimers represent novel tools for functional study. Artificial homodimers and heterodimers are functional. [br/] Conclusion: Interchangeability between ABCD1 and ABCD2 is confirmed, but PUFA transport depends on ABCD2. [br/] Significance: For the first time, heterodimers in mammals are proven to be functional.[br/] ABCD1 and ABCD2 are two closely related ATP-binding cassette half-transporters predicted to homodimerize and form peroxisomal importers for fatty acyl-CoAs. Available evidence has shown that ABCD1 and ABCD2 …
Rapid odorant release in mammalian odour binding proteins facilitates their temporal coupling to odorant signals.
2010
; We have measured the effect of rat odorant-binding protein 1 on the rates of ligand uptake and liquid-to-air transfer rates with a set of defined odorous compounds. Comparison of observed rate constants (k(obs)) with data simulated over a wide range of different kinetic and thermodynamic regimes shows that the data do not agree with the previously held view of a slow off-rate regime (k(off) <0.0004 s(-1)). We propose that a rapid koff would be a necessary requirement for such a system, since slow odorant-release rates would result in significant decorrelation between the olfactory world and odour perception. (c) 2010 Elsevier Ltd. All rights reserved.
Modular Assembly of Multimodal Imaging Agents through an Inverse Electron Demand Diels–Alder Reaction
2019
International audience; The combination of two imaging probes on a same biomolecule gives access to targeted bimodal imaging agents that can provide more accurate diagnosis, complementary information, or that may be used in different applications, such as PET imaging and fluorescence imagingassisted surgery. In this study, we demonstrate that dichlorotetrazine, a small, commercially available compound, can be used as a modular platform to easily assemble various imaging probes. Doubly-labeled tetrazines can then be conjugated to a protein through a biorthogonal IEDDA reaction. A series of difunctionalized tetrazine compounds containing various chelating agents and fluorescent dyes was synth…
Ecological role of mycotoxins produced by Fusarium graminearum : consequences of the presence of deoxynivalenol (DON) in crop residues on the soil mi…
2012
Fusarium graminearum is a plant pathogenic fungus, causing devastating disease “Fusarium head blight” (FHB) in cereals including wheat and maize. It also contaminates the grains with mycotoxins including deoxynivalenol (DON) which are toxic to human and animals. This disease has resulted in the serious losses in grain yield and quality. We established through a first bibliographic review that during off season fungus survives saprophytically on the crop residues (ecological habitat) and serves as primary inoculum for the next season crop. However, we noticed also that the literature was poor about the role mycotoxins could play in the establishment of F. graminearum in such a habitat. The m…
Clathrin-mediated endocytosis: an early event triggered by an elicitor of defence reaction in tobacco
2007
International audience