1,721,007 research outputs found
Discovery of a new strain of Heterorhabditis bacteriophora and use of the inbred line approach to optimize its virulence and cold tolerance
Get PDFSerial culturing which leads to trait deterioration is a significant concern in the entomopathogenic nematode production industry for both in vivo and in vitro methods. Prior research indicates that generation of homozygous inbred lines can deter trait loss within a nematode population. I hypothesized that the inbred line approach can be combined with discovery (isolation of new genetic material) to create stable nematode strains with superior biocontrol potential. My objective was to test this hypothesis, in relation to developing superior virulence in colder temperatures. A putative cold-tolerant strain of Heterorhabditis bacteriophora was isolated from a local soil sample in southern Ontario. Ten homozygous inbred lines were generated and screened for biocontrol characteristics, including reproductive capacity, storage stability and virulence in a series of different temperatures. Superiority of the inbred lines compared to their wild-type parents, whether sub-cultured or non-cultured, as well as two commercial strains, was observed. Inbred line 415 exhibited very poor virulence, storage stability, reproductive capacity in small-scale and serial culturing trials, whereas inbred line 324 had the best storage stability, high virulence and reproductive capacity among all passages. Hence, this superior line – inbred line 324 – was selected for commercial use. Furthermore, the hypothesis that discovery can be combined with the inbred line approach to develop stable and superior nematodes for biocontrol was supported
Bacteria
No full textThis chapter helps the readers to update current knowledge of the ecology of entomopathogenic bacteria, the use of new tools to examine their interactions with the environment, and factors affecting their distribution and abundance. It includes case studies on specific bacteria and looks at how bacterial ecology affects the use and impact of bacterial entomopathogens in microbial control. Transmission is one of the key factors determining successful continuance of a bacterial entomopathogen. Most bacteria infect their hosts through horizontal transmission. Entomopathogenic cells ingested during insect feeding cause infection, the pathogen multiples within the host, and new propagules are released to the environment to infect more hosts. Virulence is considered a measurable characteristic of the ability of the microbe to cause disease and is intended for within-group or within-species pathogen comparisons. Many plant pathogens can increase their virulence through a quorumsensing mechanism mediated by the level of N-acyl homoserine lacton
Fungi
No full textSummary This chapter investigates the recent results of studies of the ecology of fungal pathogens, including ecological insights obtained by implementation of molecular tools. It spans a spectrum of invertebrates as hosts, although emphasis will be on pathogens of terrestrial insects, which have been the focus of most ecological research. Some taxa of invertebrate pathogenic fungi have evolved adaptations for utilizing living plants as substrates, and these lifestyles have recently received increased attention from researchers following the initial documentations of such plant associations by Beauveria and Metarhizium. This topic has recently been reviewed; the chapter mainly focuses on aspects of ecological relevance, including trophic interactions. Fungal pathogens are used to provide biological control in numerous ways. The primary type of biological control emphasized for fungal pathogens is inundative augmentation, in which biological control agents are applied for immediate impact based on the propagules released
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
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