1,720,966 research outputs found
Nutrient competition and coevolutionary antagonistic interactions between Fusarium and Streptomyces in soil
No full textUniversity of Minnesota Ph.D. dissertation.October 2016. Major: Plant Pathology. Advisor: Linda Kinkel. 1 computer file (PDF); vii, 109 pages.Plant impacts on nutrient use profiles among rhizosphere microbes are poorly understood. We examined the effects of plant host and plant species richness on nutrient use profiles of Streptomyces isolated from the rhizosphere of the prairie plants Andropogon gerardii (Ag) and Lespedeza capitata (Lc) growing in communities of 1 (monoculture) or 16 (polyculture) plant species. Growth on 95 carbon sources was assessed over time. Mean niche width and mean growth were significantly greater for isolates from polyculture vs. monoculture plots, and for Streptomyces from Lc vs. Ag. Isolates from high-carbon (polyculture) or high-nitrogen (Lc) soils had larger niche widths than isolates from low-C (monocultures) or low-N (Ag) soils. Isolates from polycultures were significantly more niche (nutrient) differentiated than isolates from monocultures. We also characterized antagonistic phenotypes and nutrient use among sympatric Streptomyces and Fusarium. Streptomyces from monocultures were more antagonistic against sympatric Fusarium populations than isolates from polycultures. In contrast, Fusarium isolates from polycultures were more inhibitory against sympatric Streptomyces than isolates from monocultures. Fusarium isolates from monocultures had greater niche overlap with Streptomyces than those from polycultures, suggesting greater potential for Fusarium to compete with Streptomyces in monoculture plant communities. In contrast, Streptomyces from polycultures had greater niche overlap with sympatric Fusarium than those from monocultures, suggesting that Fusarium experience greater competition from Streptomyces in polyculture than monoculture. These patterns are consistent with selection for Fusarium-antagonistic Streptomyces populations in the presence of strong Fusarium competition in monocultures, and selection for Streptomyces-inhibitory Fusarium populations in the presence of Streptomyces resource competition in polycultures. Finally, we found evidence for local adaptation between Fusarium and Streptomyces populations as evidenced by the presence of significantly greater inhibition among sympatric than allopatric populations in prairie soil. Additionally, for both taxa, there was a significant positive correlation between the strength of inhibition against each taxon and the intensity of resource competition from that taxon, supporting the hypothesis that antibiotics act as weapons in soil communities. Collectively, these results suggest that coevolutionary antagonistic interactions between Fusarium and Streptomyces in soil are driven by resource competition.ESSARIOUI, Adil. (2016). Nutrient competition and coevolutionary antagonistic interactions between Fusarium and Streptomyces in soil. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/183379
Détermination du biotype du nématode des agrumes (Tylenchulus semipenetrans) dans cinq régions agrumicoles du Maroc
Get PDFThe biotype of citrus nematode (Tylenchulus semipenetrans) from Morocco was determined using differential plant hosts, namely trifoliate orange (Poncirus trifoliata), bitter orange (Citrus aurantium), grape (Vitis vinifera) and olive (Olea europaea). The study was conducted under greenhouse conditions with 5 replicates. Nematodes from regions of Gharb, Souss-Masssa, Haouz, Loukkos and Moulouya were extracted from roots and inoculated to hosts with 10.000 eggs and juveniles per plant. Reproductive factors were less than one for Poncirus trifoliate and olive for all populations. Result of differential-host experiment showed that all five T. semipenetrans populations belong to the Mediterranean biotype.
Keywords: Citrus nematode, regions, Differential host test, Mediterranean biotype.Un essai a été mené sous tunnel plastique à l’INRA de Kénitra (El Menzeh) en vue de caractériser les différents biotypes du nématode des agrumes (Tylenchulus semipenetrans) existants dans les vergers marocains. Les plantes hôtes différentielles utilisées dans ce test sont le citronnier épineux (Poncirus trifoliata), le bigaradier (Citrus aurantium), la vigne (Vitis vinifera) et l’olivier (Olea europaea). Les différentes plantes hôtes ont été inoculées par une suspension de 10.000 d’œufs et juvéniles de deuxième stade de T. semipenetrans des régions du Gharb, Loukkos, Haouz, Moulouya et Souss-Massa. Les différentes populations de T. semipenetrans ont montré une forte capacité à se multiplier sur le bigaradier et aussi sur la vigne, contrairement à l’olivier et le P. trifoliata. Le taux de reproduction (TR) des différentes populations de T. semipenetrans sur le porte-greffe P. trifoliata et l’olivier est inférieur à 1, contrairement au bigaradier et la vigne où ce taux de reproduction est supérieur à 1. Ces résultats indiquent que les cinq populations de T. semipenetrans des régions du Gharb, Loukkos, Haouz, Moulouya et Souss- Massa appartenant au biotype Méditerranéen.
Mots-clés: Nématode des agrumes, régions, Plantes hôtes, Biotype Méditerranéen
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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