1,720,968 research outputs found
Rôle de l’inoculation mycorhizienne dans la modulation du transcriptome foliaire du blé et l’induction d’une résistance contre Zymoseptoria tritici
No full textThis thesis project takes place in the context of the transition from conventional agriculture to more sustainable practices, which requires the development of new farming methods that are more respectful of human health and the environment. The reduction in the use of chemical inputs is accompanied by the development of biosolutions, some of which involve the use of beneficial microorganisms, such as arbuscular mycorrhizal fungi (AMF), to improve plant growth and health. These AMF have shown the ability to induce resistance in plants against certain fungal pathogens, known as Mycorrhizal-Induced Resistance (MIR). Thus, this research aims to evaluate the ability of the AMF Funneliformis mosseae to protect wheat against Septoria tritici blotch (STB), a major foliar disease in wheat caused by the hemibiotrophic fungus Zymoseptoria tritici. This thesis work revolves around three main objectives : (i) to analyze the transcriptomic modifications induced by F.mosseae at the foliar tissues during the establishment of mycorrhizal symbiosis in the roots ; (ii) to understand the foliar molecular mechanisms involved in the protection of bread wheat against STB, induced by F.mosseae ; and (iii) to characterize the microbial communities associated with the roots and rhizosphere of three plant species, including wheat, cultivated on soil from organic wheat fields in the Hauts-de-France region. The analysis of the co-occurrence networks of these microbial communities will help design microbial inocula enriched with AMF, better adapted to local pedoclimatic conditions. Our results showed that, alongside the increase in root colonization by F.mosseae, a systemic response was observed in wheat leaves as early as the 19th day of cultivation, with a marked activation of numerous leaf gene expressionsstarting from the 42nd day of co-culture. Although plant biomass was not affected by root mycorrhization, several metabolic pathways were simulated, including proteolysis, carbon metabolism, photorespiration (accompanied by stoamatal closure), antioxidant mechanisms, as well as hormonal signaling pathways involving abscisic acid, jasmonic acid, and ethylene, along the activation of defense-related genes. Surprisingly, an upregulation of a large number of these same genes is similarly observed in wheat leaves in response to inoculation by the pathogenic fungus, Z.tritici. Moreover, in mycorrhizal plants subsequently inoculated with Z.tritici, genes coding for proteins involved in photosynthesis are repressed, which could play a role in the plant's ability to limit the development of Z.tritici during its biotrophic phase. Indeed, a 35% reduction in STB symptoms was observed in mycorrhizal plants compared to non-mycorrhizal plants. Furthermore, to optimize the benefits of mycorrhization, the choice of inoculum if crucial. For this reason, a study was carried out to characterize the microbial communities associated with the roots and rhizophere of wheat. This analysis was conducted in comparison with two other mycotrophic plant species (leek and clover) to better understand the wheat-associated microbiota and its possible specificities. Our results showed that microbial diversity (bacteria, total fungi and AMF) was consistenly higher in the rhizosphere than within the roots, regardless of the plant species. In wheat, interactions between AMF and other microorganisms are fewer and different from those observed in leek and clover, where AMF showed strong interactions with nitrogen-fixing, phosphorus-solubilizing, and growth-promoting bacteria. These results underscore the importance of gaining a deeper understanding of wheat-associated microbiota to design more effective AMF-based microbial inocula, providing a more efficient biocontrol strategy against Z.tritici.Cette thèse s’inscrit dans un contexte de transition vers une agriculture plus durable nécessitant le développement de pratiques agricoles respectueuses de la santé humaine et de l’environnement, notamment en réduisant l’usage des pesticides chimiques. L’utilisation des champignons mycorhiziens à arbuscules (CMA), comme potentiels agents de biocontrôle, représente une alternative prometteuse aux fongicides chimiques. Ainsi, ce travail a pour objectif d’évaluer la capacité du CMA Funneliformis mosseae à induire une protection systémique chez le blé contre Zymoseptoria tritici, champignon hémibiotrophe, responsable de la septoriose, maladie foliaire majeure en région Hauts-de-France. Cette thèse vise, notamment à : (i) analyser les modifications transcriptomiques induites par F. mosseae au niveau foliaire, au cours de l’établissement de la symbiose mycorhizienne dans les racines ; (ii) comprendre les mécanismes moléculaires foliaires impliqués dans la protection du blé contre la septoriose, induits par F. mosseae; et (iii) caractériser les communautés microbiennes associées aux racines et à la rhizosphère de 3 plantes, dont le blé, cultivés sur un sol issu de champs de blé de notre région. Nos résultats ont montré que parallèlement à l’augmentation de la colonisation racinaire, une réponse systémique est observée dans les feuilles de blé dès le 19e jour de culture, avec une activation marquée de l’expression de nombreux gènes des tissus foliaires à partir du 42e jour de co-culture. Bien que la biomasse des plantes ne soit pas affectée par la mycorhization des racines de blé, plusieurs voies métaboliques sont stimulées (mobilisation des phosphates, protéolyse, métabolisme du C, photorespiration, mécanismes antioxydants, voies hormonales de signalisation liées à l’ABA, l’AJ et l’ET, activation de gènes de défense). Un grand nombre de ces mêmes gènes est également induit dans les feuilles de blé en réponse à l’inoculation par Z. tritici. Par ailleurs, une répression des gènes codant des protéines impliquées dans la photosynthèse observée chez les plantes mycorhizées pourrait jouer un rôle dans la capacité de la plante à limiter le développement de Z. tritici lors de sa phase biotrophe. En effet, une réduction de 35 % des symptômes de la septoriose a été observée chez les plantes mycorhizées par rapport aux non-mycorhizées. Par ailleurs, ce travail a été complété par une étude de caractérisation des communautés microbiennes associées au blé, en comparaison avec 2 autres plantes mycotrophes (poireau et trèfle), pour mieux appréhender le microbiote du blé et ses éventuelles spécificités. Nos résultats ont révélé que la diversité microbienne (bactéries, champignons totaux et CMA) était plus élevée au niveau de la rhizosphère qu'au sein des racines, et ce quelle que soit l’espèce végétale étudiée. De plus, il a été observé que le blé présente une diversité microbienne plus importante que celle du trèfle et du poireau. En comparaison au blé, ces dernières espèces montrent une diversité plus spécifique en CMA et sont enrichies en NFB et PGPR. L’analyse des réseaux de co-occurrence a mis en évidence des interactions microbiennes majoritairement positives, impliquant principalement des bactéries dans les racines, et des champignons dans la rhizosphère, quelle que soit la plante. Les CMA appartenant aux ordres des Glomerales et Diversisporales interagissent fortement avec les autres communautés microbiennes; certaines sont généralistes, d’autres spécifiques à certaines espèces végétales. Chez le blé, les interactions entre les CMA et les autres microorganismes sont moins nombreuses et différent de celles observées chez le poireau et le trèfle, où les CMA interagissent fortement avec des NFB, des PSB et PGPR. Ces résultats mettent en évidence l’intérêt d’approfondir la connaissance du microbiote du blé, afin de concevoir des inoculums mycorhiziens optimisés, pouvant constituer une stratégie de biocontrôle plus efficace contre Z. tritici
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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