1,720,961 research outputs found
Architecture génétique des caractères reliés au bois, à la croissance et à la résistance contre la tordeuse des bourgeons de l’épinette chez l’épinette blanche
No full textLes analyses d’association visent à mieux comprendre l’architecture génétique des caractères quantitatifs comme ceux reliés à l’adaptation, la croissance et la structure du bois, et mettre en évidence les gènes qui les contrôlent. Ces connaissances sont utiles pour notamment mieux appréhender le potentiel de résilience dans le contexte de changements climatiques, ainsi que pour la conservation et l’amélioration génétique des arbres forestiers. Cette thèse porte sur l’épinette blanche (Picea glauca [Moench] Voss) avec deux objectifs principaux : 1) développer une compréhension plus intégrée des caractères quantitatifs, et ; 2) développer des stratégies permettant de mieux exploiter les analyses d’association face aux contraintes génétiques et statistiques liées à leur utilisation chez les arbres forestiers. La thèse s’appuie sur deux études d’association qui portent respectivement sur la croissance et les caractéristiques physiques du bois (chapitre 2), et la résistance contre la tordeuse des bourgeons de l’épinette (TBE, Choristoneura fumiferana Clemens) (chapitre 3). Nous avons d’abord analysé les caractéristiques du bois ainsi que la croissance en utilisant un seuil de significativité statistique permissif (P < 0,05; sans correction pour tests multiples) pour maximiser la découverte de gènes comportant des SNPs significatifs. Selon les caractères étudiés, entre 229 et 292 gènes ont été identifiés, qui ont ensuite été soumis à des analyses complémentaires portant sur leurs annotations fonctionnelles et leur expression tissulaire. Les gènes associés aux caractères du bois se sont montrés surreprésentés dans un groupe de co-expression préférentiel au xylème secondaire. Une analyse de réseau de ce groupe de gènes a permis d’identifier certains facteurs de transcription de type MYB et NAC ayant un niveau de connectivité élevé, dont notamment PgNAC-7 qui était le gène ‘hub’ le plus connecté, suggérant un rôle dans la régulation des caractères physiques du bois. L’étude des caractères de défense contre la TBE s’est appuyée sur trois méthodes d’analyse d’association considérant soit un locus à la fois, plusieurs loci, ou encore plusieurs caractères simultanément. Les analyses ont permis d’identifier 33 gènes ayant des fonctions métaboliques variées et expliquant une proportion élevée de la variation phénotypique observée. Des corrélations phénotypiques faiblement positives ont également été observées entre la croissance et les facteurs de résistance contre la TBE, indiquant l’absence d’un compromis métabolique entre ces caractères. Nos résultats indiquent que les stratégies proposées dans la présente thèse pourraient être appliquées à d’autres caractères quantitatifs et permettre de développer des connaissances utiles pour mieux comprendre l’architecture génétique des caractères complexes chez les arbres forestiers.The general aim of association analyses is to decipher the genetic architecture of quantitative traits such as those related to adaptation, growth and wood structure, and to highlight the genes that control them. This knowledge is useful to better understand the potential for resilience toward climate change, and for the genetic conservation and improvement of forest trees. This thesis focuses on white spruce (Picea glauca [Moench] Voss) and has two main objectives: 1) develop a more integrated understanding of quantitative traits, and; 2) develop strategies to better exploit association analyses despite the genetic and statistical constraints related to their use in forest trees. The thesis is based on two association studies, which focus respectively on growth and wood physical traits (Chapter 2), and resistance to spruce budworm (SBW, Choristoneura fumiferana Clemens) (Chapter 3). We first analyzed wood and growth traits using a permissive threshold of statistical significance (P < 0.05, without correction for multiple tests) to maximize the discovery of genes carrying significant SNPs. For each of the traits studied, between 229 and 292 such genes were identified, which were then subjected to further analyses based on their functional annotations and their tissue expression. The genes associated with wood traits were over-represented in a co-expression group that is preferential to secondary xylem. A network analysis of this group of genes allowed identifying certain transcription factors of MYB and NAC types with a high level of connectivity, including PgNAC-7 which was the most connected hub gene, suggesting a role in the regulation of wood physical traits. The study of SBW defence traits was based on three methods of association analysis considering one locus at a time, several loci, or several traits simultaneously. The analyses identified 33 genes with various metabolic functions, which explained a major proportion of the observed phenotypic variation. Weakly positive phenotypic correlations were also observed between growth and resistance traits against SBW, indicating the absence of a metabolic trade-off between these traits. Our results indicate that the strategies proposed in this thesis could be applied to other quantitative traits to develop a better understanding of the genetic architecture of complex traits in forest trees
Analyse comparative de la diversité génétique et de la structure des populations chez l'orge (Hordeum vulgare L.) à l'aide de marqueurs SSR, DArT et du pedigree
No full textLa diversité génétique de 92 cultivars d'orges canadiennes a été mesurée en utilisant deux types des marqueurs moléculaires (SSR et DArT) et le pedigree. Au total, 368 alleles ont été identifiés aux 50 locus SSR et utilisés pour créer une matrice de distance génétique. Le nombre d'allèles par locus variait de 2 à 13 (x = 7,36) et l'indice PIC variait entre 0,34 et 0,86 (x = 0,69). Pour les marqueurs bialléliques DArT, la matrice de distance génétique s'est basée sur 971 marqueurs dont les indices PIC variaient entre 0,06 et 0,50 (x = 0,39). Une troisième matrice de distance a été calculée basée sur le coefficient de parenté. Un groupement des génotypes a été effectué basé sur les trois matrices de distances génétiques et les dendrogrammes obtenus ont montré des relations génétiques parmi les cultivars d'orge. Une comparaison de la similarité topologique des trois dendrogrammes réalisée en utilisant l'indice de congruence a montré une très bonne concordance entre les trois dendrogrammes. Des analyses statistiques ont par ailleurs montré une corrélation fortement significative entre les matrices SSR et DArT (r = 0,80, p< 0,002) mais une plus faible corrélation positive du pedigree avec les deux types de marqueur (r = 0,46, p<0,002; r = 0,52, p< 0,002). Ces informations comparant les résultats de différentes méthodes d'estimation de la diversité génétique seront utiles pour l'amélioration et la conservation des ressources génétiques d'orge
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
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