1,720,989 research outputs found
Impact de la structure du génome sur l'organisation, la régulation et la fonction des gènes sur le chromosome 3B du blé hexaploïde (Triticum aestivum L.)
No full textDu fait de sa taille (17 Gb), de sa nature allohexaploïde et de son fort taux de séquences répétées (>80%), le génome du blé tendre a toujours été considéré comme trop complexe pour des analyses moléculaires efficaces. En conséquence, la connaissance de la structure de son génome reste limitée. Utilisant une approche chromosome-spécifique, la carte physique du chromosome 3B du blé a récemment été établie et a permis le développement de ressources génomiques uniques. Pendant ma thèse, la mise en oeuvre d‟approches transcriptomiques utilisant ces ressources m‟a permis d‟analyser les relations entre la structure du génome, l‟évolution, la fonction et la régulation des gènes le long du chromosome 3B de blé. Tout d‟abord, des filtres portant les BAC du « Minimal Tiling Path » (MTP) du chromosome 3B ont été hybridés avec 15 échantillons d‟ARNm pour identifier les BAC portant des gènes. Ensuite, des puces Agilent 15K d‟expression d‟orge ont été hybridées avec les pools tridimensionnels (3D) du MTP du chromosome 3B pour localiser les gènes plus précisément sur la carte physique. Afin de construire la première carte transcriptionnelle d‟un chromosome de blé, ces mêmes pools 3D ainsi que les 15 échantillons d‟ARNm ont été hybridés sur des puces NimbleGen 40K d‟expression de blé. Les résultats obtenus à partir de ces expériences ont permis de tirer des conclusions quant à l‟organisation de l‟espace génique sur le chromosome 3B. Ainsi les gènes sont répartis tout le long du chromosome 3B selon un gradient de densité de gènes du centromère vers les télomères avec une plus forte proportion de gènes regroupés en îlots au niveau des télomères. Une analyse évolutive a montré que les îlots seraient essentiellement constitués de gènes ayant subi des réarrangements dans le génome du blé. De plus, la carte transcriptionnelle a également mis en évidence qu'une part significative des gènes organisés en îlot présentent des profils d‟expression similaires et / ou ont la même fonction et / ou interviennent dans le même processus biologique. De plus, à l‟échelle du chromosome 3B entier, des mécanismes de régulation à longue distance entre îlots de gènes ont été suspectés. En conclusion, cette étude a permis pour la première fois de mettre en évidence des relations entre la structure du génome, l‟évolution, la fonction et la régulation des gènes à l‟échelle d‟un chromosome de blé. Le séquençage et l‟annotation du chromosome 3B ainsi que l'utilisation de technologies telles que le RNAseq permettront d‟analyser ces relations de façon encore plus précise et exhaustive.Because of its size (17 Gb), allohexaploid nature and high repeat content (>80%), the bread wheat genome has always been perceived as too complex for efficient molecular studies. As a consequence, our knowledge of the wheat genome structure is still limited. Following a chromosome-specific approach, the physical map of wheat chromosome 3B has recently been constructed and allowed the development of unique genomic resources. During my PhD the use of transcriptomic approaches based on these resources allowed me analysing the relationships between the structure of the genome, the evolution, the function and the regulation of the genes along wheat chromosome 3B. First macroarrays carrying the BACs of the chromosome 3B “Minimal Tiling Path” (MTP) were hybridised with 15 mRNA samples to identify the BACs carrying genes. Then barley Agilent 15K expression microarrays were hybridised with the MTP of chromosome 3B pooled in three-dimension (3D) to precisely locate the genes on the physical map. To build the first transcription map of a wheat chromosome, the 3D pools as well as the 15 mRNA samples were hybridised onto wheat NimbleGen 40K expression microarrays. The results from these experiments allowed drawing some conclusions about gene space organisation on chromosome 3B. Thus the genes are spread all along chromosome 3B with a gradient of the gene density from the centromere to the telomeres with a higher proportion of genes organised in islands at the telomeres. An evolutionary analysis demonstrated that the islands would essentially be composed of genes that have undergone rearrangements in the wheat genome. Furthermore the transcription map also showed that a significant fraction of the genes organised in islands display similar expression profiles and / or share the same function and / or play a role in the same biological process. Moreover, at the scale of the whole chromosome 3B, mechanisms of long distance regulation between gene islands were suspected. In conclusion this study allowed for the first time to find relationships between the genome structure, the evolution, the function and the regulation of the genes at a wheat chromosome scale. The sequencing and the annotation of chromosome 3B as well as the use of technologies like RNAseq will enable to analyse these relationships in an even more precise and exhaustive way
Resequencing of seven genotypes of Muscadinia rotundifolia (Illumina GAII PE 2x100bp, about 10x)
No full textAbstract:Muscadinia rotundifolia, an American species related to the European grapevine Vitis vinifera, has a high level of resistance to grapevine diseases. Backcross-based introgression has been used in French breeding programmes to transfer resistance factors from M. rotundifolia into cultivated backgrounds while eliminating the unwanted cultural traits and off-flavours. However, crosses between the two species have a low success rate, most of the hybrids are sterile, and phenotypic abnormalities are common in the offspring. In this context, it is essential to identify the genomic features that impede crosses between the two species. To this end, three mapping populations were generated by pseudo-backcrosses using M. rotundifolia as the donor parent and several V. vinifera cultivars as the recurrent parents. Genotyping-by-sequencing was used to establish high-density genetic linkage maps and to determine the origin of each segment of the chromosomes. Several segregation distortion regions were identified. In these regions, M. rotundifolia alleles were either conserved either eliminated. In addition, a high level of macrosynteny was observed between the parents of the pseudo-backcross 1 population. In this population, recombination rate variations were similar along the genome of both parents except on chromosome 7 of V. vinifera which correspond to chromosomes 7 and 20 of M. rotundifolia. In following pseudo-backcrosses, recombination rate abnormalities were observed on chromosomes with homeologous regions, i.e. regions with one allele from M. rotundifolia and one allele from V. vinifera. On these chromosomes, recombinations concentrate in homologous regions, and few or no recombinations are observed in the homeologous regions. These results will help breeders to select a suitable breeding strategy. The dataset is provided in support of the data paper: “Understanding recombination distribution in Muscadinia rotundifolia x Vitis vinifera backcrosses to improve grapevine breeding strategies” by Delame M., Prado E., Blanc S., Robert G., Mestre P., Rustenholz C., Merdinoglu D. (in preparation)
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
Génomique structurale, comparative et fonctionnelle pour décrire et comprendre l’organisation et la diversité des génomes de plantes d’intérêt agronomique
No full textInternational audienc
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
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