1,721,010 research outputs found
Enhancing drought resistance in perennial ryegrass (Lolium perenne) using seaweed extract compounds : development of a bioassay and investigation of underlying mechanisms.
No full textFace au dérèglement climatique et aux limites des pratiques agricoles, les biostimulants apparaissent comme des leviers durables pour renforcer la résilience des cultures. Les extraits d'algues suscitent un intérêt croissant pour leur capacité à améliorer les rendements, la qualité et la tolérance aux stress des plantes. Cette thèse explore l’effet biostimulant d’un extrait de Laminaria digitata sur le ray-grass anglais (Lolium perenne), espèce dominante des prairies normandes. Les objectifs étaient (i) d’étudier les mécanismes de résistance à la sécheresse chez L. perenne, dont le rôle des glucides solubles dans la protection des méristèmes foliaires, (ii) d’évaluer le potentiel biostimulant sur la résistance à la sécheresse d’un extrait de L. digitata en lien avec ses composés glucidiques (alginates, fucoïdanes, laminaranes et mannitol), et (iii) d’identifier les modes d’action des extraits d’algues par une analyse transcriptomique des méristèmes foliaires des plantes traitées. Les travaux ont montré que l’accumulation de glucides solubles et en particulier de fructanes de haut degré de polymérisation, dans les méristèmes foliaires lors de la sécheresse, s’accompagne d’une augmentation de leurs teneurs dans le fluide apoplastique. Leur immunolocalisation par fluorescence et marquage à l’or indique qu’ils migrent de la vacuole vers l’apoplaste dans le mésophylle des méristèmes foliaires. De plus, les fructanes de L. perenne ont montré une forte activité de piégeage du radical hydroxyle, et qu’ils sont connus pour stabiliser les membranes en interagissant avec les phospholipides membranaires, les résultats indiquent que les fructanes jouent un rôle crucial dans la protection des méristèmes foliaires au cours de la déshydratation et contribuent à la protection du tonoplaste et du plasmalemme. Le traitement foliaire 7 jours avant le début de la sécheresse avec un extrait de L. digitata a conduit à l’amélioration de la résistance à la sécheresse via la protection du méristème foliaire et de la résilience. De plus un effet dose de type hormésis a été mis en évidence. La dose de 2 L.ha-1 a présenté les effets les plus bénéfiques et la dose la plus forte (15 L.ha-1) a conduit à des effets délétères. Au champ, le traitement avec la dose de 2 L.ha-1 a conduit à une amélioration de la repousse après défoliation. L’évaluation des effets de solutions contenant des concentrations différentes en alginates, fucoïdanes, laminaranes et mannitol a mis en évidence que leurs effets sur la protection des méristèmes foliaires pendant la sécheresse et sur la croissance et l’absorption d’azote après la récupération dépendent de leur contenu en fucoïdanes, laminaranes et mannitol. Les résultats indiquent aussi que les mécanismes impliqués dans la protection des méristèmes diffèrent selon la composition de l’extrait, les solutions contenant une proportion plus importante de fucoïdanes sont associées à une accumulation de fructanes pendant la sécheresse. Les résultats préliminaires de l’analyse des données transcriptomiques ont permis de mettre en évidence que le nombre de DEGs varie selon la composition des extraits pulvérisés. Les analyses préliminaires d’enrichissement des GO terms associés à des processus biologiques indiquent que le traitement avec une solution contenant une proportion importante de laminaranes module l’expression de gènes associés à la réplication de l'ADN et à la division cellulaire, tandis que le traitement avec une solution contenant une proportion importante de mannitol module l’expression de gènes associés aux réponses aux stimuli abiotiques ainsi que ceux liés au métabolisme des glucides et à la photosynthèse. Afin de mieux comprendre les mécanismes sous-jacents impliqués dans les réponses physiologiques observées suite aux traitements avec les extraits d’algues, l’analyse des données transcriptomiques doit être poursuivie et complétée par des mesures ciblées du niveau d’expression par qPCR des gènes d’intérêts.In the context of climate change and the limitations of conventional agricultural practices, biostimulants are emerging as sustainable tools for improving crop resistance. Seaweed extracts are receiving increasing attention for their ability to improve plant yield, quality and stress tolerance. This thesis investigates the biostimulant effect of a Laminaria digitata extract on perennial ryegrass (Lolium perenne), a dominant grass species in Normandy pastures. The main objectives were (i) to explore the mechanisms of drought resistance in L. perenne, focusing on the role of soluble carbohydrates in protecting leaf meristems, (ii) to assess the potential for promoting drought tolerance of an extract of L. digitata extract as a function of its carbohydrate content (alginates, fucoidans, laminarans, and mannitol), and (iii) to identify the molecular underlying mechanisms of the algal extract by transcriptomic analysis of leaf meristems in treated plants.The results highlight that the accumulation of soluble carbohydrates, particularly high DP fructans, in leaf meristems during drought stress coincides with increased concentrations in the apoplastic fluid. Fluorescence immunolocalization and gold labeling revealed a migration of these fructans from the vacuole to the apoplast in mesophyll cells of the leaf meristem. Given that L. perenne fructans have demonstrated strong hydroxyl radical scavenging activity and are known to stabilize membranes through interaction with phospholipids, these results suggest a key role for fructans in meristems protection during dehydration by protecting both the tonoplast and plasma membrane.Foliar application of L. digitata extract seven days before drought significantly improved drought resistance through meristems protection (maintenance of water content and membrane stability, partly linked to fructan accumulation), as well as post-drought resilience through increased nitrogen uptake. A dose-dependent hormetic effect was observed, with 2 L.ha-1 being the most effective dose, while the highest dose (15 L.ha-1) induced adverse effects. Field trials confirmed that treatment with the 2 L.ha-1 dose improved regrowth after defoliation in L. perenne. Testing of various solutions with different concentrations of alginates, fucoidans, laminarans and mannitol revealed that the protective effects on meristems during drought and the stimulation of growth and nitrogen uptake on rehydration were dependent on fucoidans, laminarans and mannitol content. The results also suggest that protective mechanisms differ according to extract composition, with fucoidans- rich solutions correlating with increased fructan accumulation under drought stress.Preliminary analysis of transcriptomic data has shown that the number of differentially expressed genes (DEGs) varies according to the composition of the seaweed extracts applied. Initial Gene Ontology (GO) enrichment analyses of biological processes suggest that treatment with laminarans -enriched solutions modulates the expression of genes involved in DNA replication and cell division, while mannitol-enriched treatments affect the expression of genes related to responses to abiotic stress, carbohydrate metabolism and photosynthesis. To further elucidate the molecular mechanisms underlying physiological responses to algal extracts, ongoing transcriptomic analyses will be complemented by targeted qPCR-based gene expression profiling
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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