11 research outputs found
Impact des génotypes de blé sur le métabolisme secondaire des Pseudomonas et conséquences sur leurs interactions avec la plante hÎte
The plant root adhering soil houses an important microbial community. Roots exude a wide variety of secondary metabolites able to attract and/or control a large diversity of microbial species. In return, among the root microbiota, some bacteria are able to promote plant development, using plant growth-promotion and plant protection properties. These bacteria are named PGPR for Plant Growth-Promoting Rhizobacteria. Some PGPR belong to the Pseudomonas genus. Pseudomonas are known to produce a wide diversity of secondary metabolites that could have biological activity on the host plant and other soil microorganisms. But yet, the impact of lifetyle and host plant on Pseudomonas secondary metabolism is still poorly understood. The aim of our project is to better understand the impact of plant-bacteria interactions on organisms physiology and highlight chemical mediators of these interactions. For that, a metabolomic approach was developed in order to characterize plant-bacteria interactions between three wheat genotypes and five different fluorescent Pseudomonas strains. Work realized during this thesis allowed to characterize the impact of bacterial lifestyle and plant-bacteria interactions on physiology and plant-beneficial properties of Pseudomonas. Our data highlight specific points that had to be considered for PGPR utilization in agriculture. They also allowed to identify chemical mediators of wheat-Pseudomonas interaction. They constitute a first step and lead to numerous perspectives in order to characterize biological activities of chemical mediators, but also use this approach to study the interaction between other organisms.Le sol adhĂ©rant aux racines des plantes abrite une communautĂ© bactĂ©rienne importante et diversifiĂ©e. La plante libĂšre, en effet, au niveau de ses racines, des exsudats qui vont sĂ©lectionner des bactĂ©ries capables de les utiliser. En retour, certaines bactĂ©ries sont capables dâentretenir des relations de coopĂ©ration avec la plante, en stimulant sa croissance et en la protĂ©geant contre des pathogĂšnes. Ces bactĂ©ries phytobĂ©nĂ©fiques dites PGPR (Plant Growth-Promoting Rhizobacteria) peuvent Ă©galement interagir entre elles au sein de la communautĂ©. Le double objectif de ces travaux de thĂšse, a Ă©tĂ© de dĂ©velopper une approche mĂ©tabolomique pour Ă©tudier lâimpact du mode de vie et des interactions plante-bactĂ©ries sur la physiologie des organismes et mettre en Ă©vidence des mĂ©diateurs chimiques de lâinteraction. Pour rĂ©pondre Ă cet objectif, notre Ă©tude a Ă©tĂ© rĂ©alisĂ©e sur deux organismes modĂšles, le blĂ© tendre (Triticum aestivum L.) et des souches bactĂ©riennes appartenant au groupe des Pseudomonas fluorescents. Les travaux rĂ©alisĂ©s au cours de cette thĂšse ont permis une caractĂ©risation de lâimpact du mode de vie et des interactions sur la physiologie et lâexpression des propriĂ©tĂ©s phytobĂ©nĂ©fiques des Pseudomonas. Ils ont soulevĂ© des points concrets Ă prendre en compte dans lâutilisation appliquĂ©e des PGPR en agriculture et ont Ă©galement mis en Ă©vidence plusieurs mĂ©diateurs dâinteractions entre la plante et les Pseudomonas. Ils forment un point de dĂ©part Ă de nombreuses perspectives Ă la fois pour dĂ©finir lâactivitĂ© biologique des mĂ©diateurs mis en Ă©vidence au cours de lâĂ©tude, mais Ă©galement utiliser cette approche pour Ă©tudier dâautres interactions mettant en jeux dâautres organismes
Wheat root modulation of Pseudomonas secondary metabolism and in turn consequences on the host plant
Le sol adhĂ©rant aux racines des plantes abrite une communautĂ© bactĂ©rienne importante et diversifiĂ©e. La plante libĂšre, en effet, au niveau de ses racines, des exsudats qui vont sĂ©lectionner des bactĂ©ries capables de les utiliser. En retour, certaines bactĂ©ries sont capables dâentretenir des relations de coopĂ©ration avec la plante, en stimulant sa croissance et en la protĂ©geant contre des pathogĂšnes. Ces bactĂ©ries phytobĂ©nĂ©fiques dites PGPR (Plant Growth-Promoting Rhizobacteria) peuvent Ă©galement interagir entre elles au sein de la communautĂ©. Le double objectif de ces travaux de thĂšse, a Ă©tĂ© de dĂ©velopper une approche mĂ©tabolomique pour Ă©tudier lâimpact du mode de vie et des interactions plante-bactĂ©ries sur la physiologie des organismes et mettre en Ă©vidence des mĂ©diateurs chimiques de lâinteraction. Pour rĂ©pondre Ă cet objectif, notre Ă©tude a Ă©tĂ© rĂ©alisĂ©e sur deux organismes modĂšles, le blĂ© tendre (Triticum aestivum L.) et des souches bactĂ©riennes appartenant au groupe des Pseudomonas fluorescents. Les travaux rĂ©alisĂ©s au cours de cette thĂšse ont permis une caractĂ©risation de lâimpact du mode de vie et des interactions sur la physiologie et lâexpression des propriĂ©tĂ©s phytobĂ©nĂ©fiques des Pseudomonas. Ils ont soulevĂ© des points concrets Ă prendre en compte dans lâutilisation appliquĂ©e des PGPR en agriculture et ont Ă©galement mis en Ă©vidence plusieurs mĂ©diateurs dâinteractions entre la plante et les Pseudomonas. Ils forment un point de dĂ©part Ă de nombreuses perspectives Ă la fois pour dĂ©finir lâactivitĂ© biologique des mĂ©diateurs mis en Ă©vidence au cours de lâĂ©tude, mais Ă©galement utiliser cette approche pour Ă©tudier dâautres interactions mettant en jeux dâautres organismes.The plant root adhering soil houses an important microbial community. Roots exude a wide variety of secondary metabolites able to attract and/or control a large diversity of microbial species. In return, among the root microbiota, some bacteria are able to promote plant development, using plant growth-promotion and plant protection properties. These bacteria are named PGPR for Plant Growth-Promoting Rhizobacteria. Some PGPR belong to the Pseudomonas genus. Pseudomonas are known to produce a wide diversity of secondary metabolites that could have biological activity on the host plant and other soil microorganisms. But yet, the impact of lifetyle and host plant on Pseudomonas secondary metabolism is still poorly understood. The aim of our project is to better understand the impact of plant-bacteria interactions on organisms physiology and highlight chemical mediators of these interactions. For that, a metabolomic approach was developed in order to characterize plant-bacteria interactions between three wheat genotypes and five different fluorescent Pseudomonas strains. Work realized during this thesis allowed to characterize the impact of bacterial lifestyle and plant-bacteria interactions on physiology and plant-beneficial properties of Pseudomonas. Our data highlight specific points that had to be considered for PGPR utilization in agriculture. They also allowed to identify chemical mediators of wheat-Pseudomonas interaction. They constitute a first step and lead to numerous perspectives in order to characterize biological activities of chemical mediators, but also use this approach to study the interaction between other organisms
Wheat Metabolite Interferences on Fluorescent Pseudomonas Physiology Modify Wheat Metabolome through an Ecological Feedback
Plant roots exude a wide variety of secondary metabolites able to attract and/or control a large diversity of microbial species. In return, among the root microbiota, some bacteria can promote plant development. Among these, Pseudomonas are known to produce a wide diversity of secondary metabolites that could have biological activity on the host plant and other soil microorganisms. We previously showed that wheat can interfere with Pseudomonas secondary metabolism production through its root metabolites. Interestingly, production of Pseudomonas bioactive metabolites, such as phloroglucinol, phenazines, pyrrolnitrin, or acyl homoserine lactones, are modified in the presence of wheat root extracts. A new cross metabolomic approach was then performed to evaluate if wheat metabolic interferences on Pseudomonas secondary metabolites production have consequences on wheat metabolome itself. Two different Pseudomonas strains were conditioned by wheat root extracts from two genotypes, leading to modification of bacterial secondary metabolites production. Bacterial cells were then inoculated on each wheat genotypes. Then, wheat root metabolomes were analyzed by untargeted metabolomic, and metabolites from the Adular genotype were characterized by molecular network. This allows us to evaluate if wheat differently recognizes the bacterial cells that have already been into contact with plants and highlights bioactive metabolites involved in wheat—Pseudomonas interaction
Exploiting rhizosphere microbial cooperation for developing sustainable agriculture strategies
International audienc
A Cross-Metabolomic Approach Shows that Wheat Interferes with Fluorescent Pseudomonas Physiology through Its Root Metabolites
International audienceRoots contain a wide variety of secondary metabolites. Some of them are exudated in the rhizosphere, where they are able to attract and/or control a large diversity of microbial species. In return, the rhizomicrobiota can promote plant health and development. Some rhizobacteria belonging to the Pseudomonas genus are known to produce a wide diversity of secondary metabolites that can exert a biological activity on the host plant and on other soil microorganisms. Nevertheless, the impact of the host plant on the production of bioactive metabolites by Pseudomonas is still poorly understood. To characterize the impact of plants on the secondary metabolism of Pseudomonas, a cross-metabolomic approach has been developed. Five different fluorescent Pseudomonas strains were thus cultivated in the presence of a low concentration of wheat root extracts recovered from three wheat genotypes. Analysis of our metabolomic workflow revealed that the production of several Pseudomonas secondary metabolites was significantly modulated when bacteria were cultivated with root extracts, including metabolites involved in plant-beneficial properties
Profiling of ob/ob mice skeletal muscle exosome-like vesicles demonstrates combined action of miRNAs, proteins and lipids to modulate lipid homeostasis in recipient cells
We have determined the lipid, protein and miRNA composition of skeletal muscle (SkM)-released extracellular vesicles (ELVs) from Ob/ob (OB) vs wild-type (WT) mice. The results showed that atrophic insulin-resistant OB-SkM released less ELVs than WT-SkM, highlighted by a RAB35 decrease and an increase in intramuscular cholesterol content. Proteomic analyses of OB-ELVs revealed a group of 37 proteins functionally connected, involved in lipid oxidation and with catalytic activities. OB-ELVs had modified contents for phosphatidylcholine (PC 34-4, PC 40-3 and PC 34-0), sphingomyelin (Sm d18:1/18:1) and ceramides (Cer d18:1/18:0) and were enriched in cholesterol, likely to alleviated intracellular accumulation. Surprisingly many ELV miRNAs had a nuclear addressing sequence, and targeted genes encoding proteins with nuclear activities. Interestingly, SkM-ELV miRNA did not target mitochondria. The most significant function targeted by the 7 miRNAs altered in OB-ELVs was lipid metabolism. In agreement, OB-ELVs induced lipid storage in recipient adipocytes and increased lipid up-take and fatty acid oxidation in recipient muscle cells. In addition, OB-ELVs altered insulin-sensitivity and induced atrophy in muscle cells, reproducing the phenotype of the releasing OB muscles. These data suggest for the first time, a cross-talk between muscle cells and adipocytes, through the SkM-ELV route, in favor of adipose tissue expansion
ĂCRITURES EN LIGNE: PRATIQUES ET COMMUNAUTĂS. Sous la dir de Brigitte Chapelain. (485 p.)
"La communication Ă©crite est encore jeune" Ă©crivait R.Escarpit1 en 1973 ajoutant que celle-ci vieillissait moins vite que d'autres moyens de communication. Nous ne pouvons aujourd'hui que constater la pertinence de cette rĂ©flexion . En effet les formes de communication mĂ©diatisĂ©e par les technologies du numĂ©rique et des rĂ©seaux proposent une palette d'outils complĂ©mentaires d'Ă©criture et de lecture, d'annotation, et d'Ă©dition personnelles et collectives qui ont dĂ©veloppĂ© le traitement de texte, l'Ă©criture hypertextuelle, les mails , les chats , et des sites web comme les wikis. Ces derniĂšres annĂ©es Internet et son double pouvoir "numĂ©rique et connectique"2s'est rĂ©vĂ©lĂ©, comme ce fut le cas du livre, ĂȘtre un dispositif scripturaire, "qui condense et organise, qui schĂ©matise et appauvrit parfois"3, revalorisant le rĂŽle informationnel et cognitif de l'Ă©criture dont le dĂ©veloppement relĂšve de nombreux domaines culturels, Ă©ducatifs et professionnels. Le phĂ©nomĂšne blog est sans doute l'exemple4 le plus rĂ©cent de ces outils d'Ă©criture. Les blogs sont notamment utilisĂ©s dans des applications littĂ©raires, pĂ©dagogiques et entrepreneuriales donnant Ă l'Ă©criture en ligne des nouveaux outils moins contraignants et plus maniables. Un colloque organisĂ© Ă l'universitĂ© de Rennes 2, en Septembre 2002, a engagĂ© une rĂ©flexion pluridisciplinaire sur les dispositifs d'Ă©criture en ligne et les pratiques communautaires Ă©mergentes. La littĂ©rature, l'Ă©ducation et l'organisation qui ne sont que rarement rĂ©unies ont retenu particuliĂšrement notre attention. Le carrefour disciplinaire que constituent les sciences de l'information et de la communication permet de mettre Ă l'Ă©preuve cette problĂ©matique commune que reprĂ©sente l'Ă©criture en ligne en s'appuyant sur ces trois champs. Nous avons choisi d'en traiter deux dimensions essentielles :la dimension processuelle et la dimension organisationnelle. C'est ainsi qu'ont Ă©mergĂ© les deux thĂšmes retenus du colloque: les pratiques et les communautĂ©s de l'Ă©criture en ligne. La dimension processuelle porte sur les processus de production de ces Ă©critures: les textes produits, les modes Ă©ditoriaux qui leur sont associĂ©s, les rĂŽles de l'auteur et du lecteur, les genres d'Ă©crits. La dimension organisationnelle s'inscrit dans les structures de travail et de crĂ©ation, la gestion des personnes et des savoirs,et les modes de dĂ©veloppement et de circulation des productions d'Ă©criture. Les travaux du colloque ont tentĂ© de rĂ©pondre Ă deux grandes interrogations portant sur ces dimensions. En quoi les pratiques d'Ă©criture en ligne proposent-elles des procĂ©dures de travail et de crĂ©ation et des modĂšles de communication qui tĂ©moignent d'une rĂ©elle spĂ©cificitĂ© processuelle? Quelles formes organisationnelles et managĂ©riales caractĂ©risent ces pratiques d'Ă©criture? Comment les dĂ©finir? Peut-on parler de communautĂ©s
Functional characterization of cytochrome P450-derived epoxyeicosatrienoic acids in adipogenesis and obesity
Adipogenesis plays a critical role in the initiation and progression of obesity. Although cytochrome P450 (CYP)-derived epoxyeicosatrienoic acids (EETs) have emerged as a potential therapeutic target for cardiometabolic disease, the functional contribution of EETs to adipogenesis and the pathogenesis of obesity remain poorly understood. Our studies demonstrated that induction of adipogenesis in differentiated 3T3-L1 cells (in vitro) and obesity-associated adipose expansion in high-fat diet (HFD)-fed mice (in vivo) significantly dysregulate the CYP epoxygenase pathway and evoke a marked suppression of adipose-derived EET levels. Subsequent in vitro experiments demonstrated that exogenous EET analog administration elicits potent anti-adipogenic effects via inhibition of the early phase of adipogenesis. Furthermore, EET analog administration to mice significantly mitigated HFD-induced weight gain, adipose tissue expansion, pro-adipogenic gene expression, and glucose intolerance. Collectively, these findings suggest that suppression of EET bioavailability in adipose tissue is a key pathological consequence of obesity, and strategies that promote the protective effects of EETs in adipose tissue offer enormous therapeutic potential for obesity and its downstream pathological consequences