1,720,971 research outputs found
Evidence for plant adaptation to a future high CO<sub>2</sub> world
No full textPlant morphology and function are sensitive to rising atmospheric carbon dioxide (CO2) concentrations, but evidence that CO2 concentration can act as a selective pressure driving evolution is sparse. Plants originating from naturally high CO2 springs are subjected to elevated CO2 concentration over multiple generations, providing an opportunity to predict how adaptation to future atmospheres may occur, with important implications for future plant conservation and crop breeding strategies. Using Plantago lanceolata L. from such a site (the ‘spring’ site) and from an adjacent ambient CO2 site (‘control’ site), and growing the populations in ambient and elevated CO2 at 700 ?mol mol-1, I have characterised, for the first time, the functional and population genomics, alongside morphology and physiology, of plant adaptation to elevated CO2 concentrations. Growing plants in elevated CO2 caused relatively modest changes in gene expression, with fewer changes evident in the spring than control plants (33 vs 131 genes differentially expressed [DE], in spring and control plants respectively). In contrast, when comparisons were made between control and spring plants grown in either ambient or elevated CO2, there were a much larger number of loci showing DE (689 in the ambient and 853 in the elevated CO2 environment). Population genomic analysis revealed that genetic differentiation between the spring and control plants was close to zero with no fixed differences, suggesting that plants are adapted to their native CO2 environment at the level of gene expression. Growth at elevated CO2 led to an unusual phenotype, with an increase in stomatal density and index in the spring, but not in control plants. Focussing on previously characterised stomatal patterning genes revealed significant DE (FDR < 0.05) between spring and control plants for three loci (YODA, CDKB1;1, and SCRM2) and between ambient and elevated CO2 for four (ER, YODA, MYB88, and BCA1). We propose that the up-regulation in spring plants of two positive regulators of stomatal numbers (SCRM2 and CDKB1;1) act here as key controllers of stomatal adaptation to elevated CO2 on an evolutionary timescale. Significant transcriptome reprogramming of the photosynthetic pathway was identified, with an overall decrease in expression across the pathway in control plants, and an increase in spring plants, in response to elevated CO2. This was followed up by physiological measurements, where a significant increase (P < 0.05) in photosynthetic capacity and regeneration rate was exhibited in spring plants, compared to control plants, at both elevated and ambient CO2 concentrations. Through this comprehensive analysis, we have identified the basis of plant adaptation to elevated CO2 likely to occur in the future
Plant adaptation or acclimation to rising CO2? Insight from first multigenerational RNA-Seq transcriptome
No full textAtmospheric carbon dioxide (CO2) directly determines the rate of plant photosynthesis and indirectly effects plant productivity and fitness and may therefore act as a selective pressure driving evolution, but evidence to support this contention is sparse. Using Plantago lanceolata L. seed collected from a naturally high CO2 spring and adjacent ambient CO2 control site, we investigated multigenerational response to future, elevated atmospheric CO2. Plants were grown in either ambient or elevated CO2 (700 ?mol mol?1), enabling for the first time, characterization of the functional and population genomics of plant acclimation and adaptation to elevated CO2. This revealed that spring and control plants differed significantly in phenotypic plasticity for traits underpinning fitness including above-ground biomass, leaf size, epidermal cell size and number and stomatal density and index. Gene expression responses to elevated CO2 (acclimation) were modest [33–131 genes differentially expressed (DE)], whilst those between control and spring plants (adaptation) were considerably larger (689–853 DE genes). In contrast, population genomic analysis showed that genetic differentiation between spring and control plants was close to zero, with no fixed differences, suggesting that plants are adapted to their native CO2 environment at the level of gene expression. An unusual phenotype of increased stomatal index in spring but not control plants in elevated CO2 correlated with altered expression of stomatal patterning genes between spring and control plants for three loci (YODA, CDKB1;1 and SCRM2) and between ambient and elevated CO2 for four loci (ER, YODA, MYB88 and BCA1). We propose that the two positive regulators of stomatal number (SCRM2) and CDKB1;1 when upregulated act as key controllers of stomatal adaptation to elevated CO2. Combined with significant transcriptome reprogramming of photosynthetic and dark respiration and enhanced growth in spring plants, we have identified the potential basis of plant adaptation to high CO2 likely to occur over coming decades
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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