1,721,010 research outputs found
SOP 4.1. Taxonomic identification by light microscopy
No full textA rapid taxonomic identification is important for estimating potential risks to animal and human health caused by cyanobacteria in waters used for recreation, drinking and irrigation. Light microscopy provides a rapid means for preliminary identification and quantitative estimation of potentially toxic cyanobacteria based on their morphology (morphotypes). However, the final species assignment should rely on a polyphasic characterization of cultured strains (or population isolates) consisting of several different molecular methods, and (whenever possible) the determination of ultrastructural, physiological, biochemical, and ecological characteristics. In this chapter, we describe the major steps essential for cyanobacterial taxa identification. These include examination by light microscopy, genetic characterization by single or multiple loci sequence analyses, and by molecular typing. The value of taxonomic and molecular databases is explained. Finally, the usefulness of a polyphasic approach is highlighted by examples. Although analyses of genes known to be involved in toxin synthesis can be helpful for the identification of potentially toxic strains (or population isolates), reliable health risk assessments require confirmation by analytical measurement of the respective cyanotoxins
Divergent properties and phylogeny of 5-enol-pyruvyl-shikimate-3-phosphate synthases from cyanobacteria: evidence supporting horizontal gene transfer in the Nostocales
No full textAs it represents the target of the successful herbicide glyphosate, great attention has been paid to the shikimate pathway enzyme 5-enol-pyruvyl-shikimate-3-phosphate (EPSP) synthase. However, inconsistent results have been reported concerning the sensitivity of the enzyme from cyanobacteria, and consequent inhibitory effects on cyanobacterial growth. The properties of EPSP synthase were investigated in a set of 42 strains representative of the large morphological diversity of these prokaryotes. Publicly available protein sequences were analyzed, and related to enzymatic features. In most cases, the native protein showed an unusual homodimeric composition and a general sensitivity to micromolar doses of glyphosate. By contrast, eight out of 15 Nostocales strains were found to possess a monomeric EPSP synthase, whose activity was inhibited only at concentrations exceeding 1mM. Sequence analysis showed that these two forms are only distantly related, the latter clustering separately in a clade composed of diverse bacterial phyla. The results are consistent with the occurrence of a horizontal gene transfer event involving an evolutionarily distant organism. Moreover, data suggest that the existence of class I (glyphosate-sensitive) and class II (glyphosate-tolerant) EPSP synthases representing two distinct phylogenetic clades is an oversimplification because of the limited number of analyzed samples
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
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
Taxonomic identification of cyanobacteria by a polyphasic approach
No full textA rapid taxonomic identification is important for estimating potential risks to animal and human health caused by cyanobacteria in waters used for recreation, drinking and irrigation. Light microscopy provides a rapid means for preliminary identification and quantitative estimation of potentially toxic cyanobacteria based on their morphology (morphotypes). However, the final species assignment should rely on a polyphasic characterization of cultured strains (or population isolates) consisting of several different molecular methods, and (whenever possible) the determination of ultrastructural, physiological, biochemical, and ecological characteristics. In this chapter, we describe the major steps essential for cyanobacterial taxa identification. These include examination by light microscopy, genetic characterization by single or multiple loci sequence analyses, and by molecular typing. The value of taxonomic and molecular databases is explained. Finally, the usefulness of a polyphasic approach is highlighted by examples. Although analyses of genes known to be involved in toxin synthesis can be helpful for the identification of potentially toxic strains (or population isolates), reliable health risk assessments require confirmation by analytical measurement of the respective cyanotoxins
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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