Salicylic Acid, an Ambimobile Molecule Exhibiting a High Ability to Accumulate in the Phloem

International audienceThe ability of exogenous salicylic acid (SA) to accumulate in castor bean (Ricinus communis) phloem was evaluated by HPLC and liquid scintillation spectrometry analyses of phloem sap collected from the severed apical part of seedlings. Time-course experiments indicated that SA was transported to the root system via the phloem and redistributed upward in small amounts via the xylem. This helps to explain the peculiarities of SA distribution within the plant in response to biotic stress and exogenous SA application. Phloem loading of SA at 1, 10, or 100 mM was dependent on the pH of the cotyledon incubating solution, and accumulation in the phloem sap was the highest (about 10-fold) at the most acidic pH values tested (pH 4.6 and 5.0). As in animal cells, SA uptake still occurred at pH values close to neutrality (i.e. when SA is only in its dissociated form according to the calculations made by ACD LogD suite software). The analog 3,5-dichlorosalicylic acid, which is predicted to be nonmobile according to the models of Bromilow and Kleier, also moved in the sieve tubes. These discrepancies and other data may give rise to the hypothesis of a possible involvement of a pH-dependent carrier system translocating aromatic monocarboxylic acids in addition to the ion-trap mechanism

Impaired Embryonic Development in Mice Overexpressing the RNA-Binding Protein TIAR

TIA-1-related (TIAR) protein is a shuttling RNA-binding protein involved in several steps of RNA metabolism. While in the nucleus TIAR participates to alternative splicing events, in the cytoplasm TIAR acts as a translational repressor on specific transcripts such as those containing AU-Rich Elements (AREs). Due to its ability to assemble abortive pre-initiation complexes coalescing into cytoplasmic granules called stress granules, TIAR is also involved in the general translational arrest observed in cells exposed to environmental stress. However, the in vivo role of this protein has not been studied so far mainly due to severe embryonic lethality upon tiar invalidation.Journal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe

Contribution à la lutte contre les maladies <br />du bois de la vigne, en particulier l'esca

Esca is a fungal syndrom found in the grapevine (Vitis vinifera) vascular system. During an initial phase, Phaeoacremonium aleophilum (PA), Phaeomoniella chlamydospora (PC) and, sometimes, Eutypa lata (EL) develop then allowing a latter infection from other fungal species. The recent banning of sodium arsenite left this syndrom out of control. Our work deal with PA, PC and EL properties, and also on the impact of natural molecules and commercial fungicides on the growth of these fungi. These pathogens exhibited different responses to these treatments and one of them (PA) was poorly or not affected. In parallel, we studied the ambimobility properties of salicylic acid (SA) and some of its halogenated derivatives. Our results showed that F 30 (an acidic derivative of fenpiclonil) was mobile into grape cuttings after a foliar treatment. F 30 was partially trapped in the wood and metabolized back to its parent molecule in the root system. 5-Chlorosalicylic acid (5-ClSA) which is known to be more active than SA on plant defense stimulation exhibited a similar phloem mobility. Therefore, F 30 and 5-ClSA have been selected for testing foliar treatments on infected grape cuttings. Such exploratoring research underline the complexity of the subject studied. Chemical treatments (fungicide) which generate several constraining elements, may be included in a wider strategy of disease control.L'esca est un syndrome cryptogamique vasculaire de la vigne (Vitis vinifera). Une phase pionnière, sous la dépendance de Phaeoacremonium aleophilum (PA), Phaeomoniella chlamydospora (PC) et éventuellement de Eutypa lata (EL) permet la mise en place d'autres espèces. Depuis l'interdiction de l'arsénite de sodium, cette maladie n'est plus contrôlée. Nous avons étudié les propriétés de PA, PC et EL, en particulier l'impact sur leur croissance de fongicides commerciaux et de fongicides systémiques synthétisés au laboratoire, ainsi que de molécules naturelles. Ces pathogènes ne présentent pas la même sensibilité à ces molécules et l'un d'eux (PA) est peu affecté par divers traitements. En parallèle, nous avons étudié les propriétés d'ambimobilité de l'acide salicylique (AS) et de quelques-uns de ses dérivés halogénés. Nous avons montré que F 30, un dérivé acide du fenpiclonil, est mobile dans les boutures de vigne après application foliaire. Il est en partie retenu dans le bois et libère la molécule parent dans les racines. L'acide 5-chlorosalicylique (5-ClAS), connu pour être plus actif que AS pour stimuler les défenses naturelles, présente une mobilité voisine de celle de AS. Sur ces bases, F 30 et 5-ClAS ont été retenus pour des tests préliminaires de traitement par voie foliaire de boutures de vigne infectées. Cette recherche exploratoire souligne la complexité de la problématique, une lutte chimique (fongicide), génératrice de contraintes, devant s'intégrer dans une stratégie globale de contrôle

Exploring metabolome with GC/MS

Chapitre 6The rapidly expanding field of metabolomics has been driven by major advances in analytical tools such as mass spectrometry and the corresponding hyphenated methods such as gas chromatography (GC-MS) but also in chemometrics and bioinformatics. The metabolomic field has been mainly developed in plant sciences and GC/MS was applied very early as it allowed determining a large number of metabolites in a wide range of samples. A typical metabolomic experiment includes (i) sample preparation, (ii) derivatization, (iii) metabolic profiling by GC/MS, (iv) treatment of data set, (v) identification of key or discriminatory metabolites and eventually (vi) their quantification. Each of these steps needs to be optimized and technical choices are determined depending on the scientific objective. This chapter gives a review of technologies and methods dedicated to GC/MS-based metabolomics, as well as the description of major advances in this area in recent years and perspectives for the future. Finally, the main application area of plant metabolomics, linked to phytochemistry, gene modifications and environmental disorders, are briefly presented

Contribution à la lutte contre les maladies du bois de la vigne, en particulier l'esca

L'esca est un syndrome cryptogamique vasculaire de la vigne (Vitis vinifera). Une phase pionnière, sous la dépendance de Phaeoacremonium aleophilum (PA), Paeomoniella chlamydospora (PC) et éventuellement de Eutypa lata (EL) permet la mise en place d'autres espèces. Depuis l'interdiction de l'arsénite de sodium, cette maladie n'est plus contrôlée. Nous avons étudié les propriétés de PA, PC et EL, en particulier l'impact sur leur croissance de fongicides commerciaux et de fongicides systémiques synthétisés au laboratoire, ainsi que de molécules naturelles. Ces pathogènes ne présentent pas la même sensibilité à ces molécules et l'un d'eux (PA) est peu affecté par divers traitements. En parallèle, nous avons étudié les propriétés d'ambimobilité de l'acide salicylique (AS) et de quelques-uns de ses dérivés halogénés. Nous avons montré que F30, un dérivé acide du fenpiclonil, est mobile dans les boutures de vigne après application foliaire. Il est en partie retenu dans le bois et libère la molécule parent dans les racines. L'acide 5-chlorosalicylique (5-ClAS), connu pour être plus actif que AS pour stimuler les défenses naturelles, présente une mobilité voisine de celle de AS. Sur ces bases, F30 et 5-ClAS ont été retenus pour des tests préliminaires de traitement par voie foliaire de boutures de vigne infectées. Cette recherche exploratoire souligne la complexité de la problématique, une lutte chimique (fongicide), génératrice de contraintes, devant s intégrer dans une stratégie globale de contrôle.Esca is a fungal syndrom found in the grapevine (Vitis vinifera) vascular system. During an initial phase, Phaeoacremonium aleophilum (PA), Phaeomoniella chlamydospora (PC) and, sometimes, Eutypa lata (EL) develop then allowing a latter infection from other fungal species. The recent banning of sodium arsenite left this syndrom out of control. Our work deal with PA, PC and EL properties, and also on the impact of natural molecules and commercial fungicides on the growth of these fungi. These pathogens exhibited different responses to these treatments and one of them (PA) was poorly or not affected. In parallel, we studied the ambimobility properties of salicylic acid (SA) and some of its halogenous derivatives. Our results showed that F30 (an acidic derivative of fenpiclonil) was mobile into grape cuttings after a foliar treatment. F30 was partially trapped in the wood and metabolized back to its parent molecule in the root system. 5-Chlorosalicylic acid (5-ClSA) which is known to be more active than SA on plant defense stimulation exhibited a similar phloem mobility. Therefore, F30 and 5-ClSA have been selected for testing foliar treatments on infected grape cuttings. Such exploratoring research underline the complexity of the subject studied. Chemical treatments (fungicide) which generate several constraining elements, may be included in a wider strategy of disease control .POITIERS-BU Sciences (861942102) / SudocSudocFranceF

Optimization of metabolome extraction procedures and implementation of a PeakForest database for the identification of microorganisms compounds by LC-HRMS

International audienceThe investigation of microbial communities and their interactions with their environments is a field of research that engaged the scientific community for several decades. We study in the laboratory microorganisms isolated from freshwater and atmospheric ecosystems in different conditions. The aim of this internship was to optimize the metabolomic workflows of four microorganisms (Pseudomonas syringae, Rhodococcus rhodococcus, Microcystis aeruginosa, Chlorella spp.) from extraction to annotation of compounds. Objectives: i) Optimize metabolome extraction protocol for each microorganism, ii) Implementation of a PeakForest database with MetaCyc and NPATLAS databases, iii) Annotation of microorganism's metabolomes

A combined LC-MS and NMR approach to reveal metabolic changes in the hemolymph of honeybees infected by the gut parasite Nosema ceranae

International audienceNosema ceranae is an emerging and invasive gut pathogen in Apis mellifera and is considered as a factor contributing to the decline of honeybee populations. Here, we used a combined LC-MS and NMR approach to reveal the metabolomics changes in the hemolymph of honeybees infected by this obligate intracellular parasite. For metabolic profiling, hemolymph samples were collected from both uninfected and N. ceranae-infected bees at two time points, 2 days and 10 days after the experimental infection of emergent bees. Hemolymph samples were individually analyzed by LC-MS, whereas each NMR spectrum was obtained from a pool of three hemolymphs. Multivariate statistical PLS-DA models clearly showed that the age of bees was the parameter with the strongest effect on the metabolite profiles. Interestingly, a total of 15 biomarkers were accurately identified and were assigned as candidate biomarkers representative of infection alone or combined effect of age and infection. These biomarkers included carbohydrates (α/β glucose, α/β fructose and hexosamine), amino acids (histidine and proline), dipeptides (Glu-Thr, Cys-Cys and γ-Glu-Leu/Ile), metabolites involved in lipid metabolism (choline, glycerophosphocholine and O-phosphorylethanolamine) and a polyamine compound (spermidine). Our study demonstrated that this untargeted metabolomics-based approach may be useful for a better understanding of pathophysiological mechanisms of the honeybee infection by N. ceranae

Does the sampling technique alter the urinary metabolome?

National audienc