1,723,550 research outputs found
Galesaurus adult BP/1/5064
No full textImages from CT reconstruction of the skull of an adult Galesaurus (BP/1/5064) used to score ontogenetic stages of teeth
Chicago, Rock Island & Pacific (RI) 5064 (neg)
No full textA photograph negative showing the Chicago, Rock Island & Pacific (CRIP, RI, or ROCK) 5064, 4-8-4, Kansas City, KS
Block Card 5064 Rowland Road
No full textThis image was produced by the Auditor's Office in Lucas County, Ohio for tax assessment purposes. Associated dates are approximate. Descriptive terms related to this photograph include: Dwelling | 5064 Rowland Road (Toledo, Ohio) | Cape Cod Style | Hopeland (Toledo, Ohio) | Greenwood Area (Toledo, Ohio) | West Toledo Area (Toledo, Ohio
Het jaarverslag 1979 van de Raad van State
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5064.pdf (Publisher’s version ) (Open Access
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
Regulation of Biosurfactant Production by Quorum Sensing in Pseudomonas fluorescens 5064, the Cause of Broccoli Head Rot Disease
Get PDFBroccoli head rot is a destructive disease found in most broccoli production areas. The
main pathogen is the bacterium Pseudomonas fluorescens. P. fluorescens 5064, which
was first isolated from an infected broccoli head in SE Scotland, produces
biosurfactants that are important for bacterial establishment on the plant surface prior to
causing disease in broccoli.
Preliminary experiments performed in this study showed that biosurfactant production
in P. fluorescens 5064 was cell density dependent, which is a typical characteristic of
the quorum sensing mechanism. Quorum sensing is a bacterial communication
mechanism, which controls a number of key processes in growth, reproduction and
virulence via signalling molecules (quorum sensing signal) in many gram-negative
bacteria.
One aim of this study was to determine if biosurfactant production in P. fluorescens
5064 is controlled via quorum sensing. To do this, 35 surfactant-minus Tn5 mutants of
P. fluorescens 5064 were screened for their abilities to produce a quorum sensing
signal. Six of these biosurfactant-deficient mutants showed a large reduction in quorum
sensing signal production. In one mutant 6423, which contains a single Tn5 insertion,
the production of the quorum sensing signal was almost eliminated. Addition of
quorum sensing signal, either synthetic or extracted from wild type P. fluorescens 5064,
was able to restore biosurfactant production in mutant 6423. This strongly suggests that
quorum sensing regulates biosurfactant production in P. fluorescens 5064.
Attempts were made to clone and sequence the Tn5 disrupted gene in mutant 6423, but
the identity of the gene remains inconclusive.
The quorum sensing signal in wild type P. fluorescens 5064 was identified in this study
by High Pressure Liquid Chromatography and Mass Spectrometry as N-3-hydroxyoctanoyl-homoserine lactone, which has been shown by other researchers to be
present in P. fluorescens strain 2-79, but not in the strains F113, 7-14 and NCIMB
10586.
The discovery that biosurfactant production in P. fluorescens 5064 is regulated by
quorum sensing opens up a possibility for novel control of broccoli head rot. Although
only the control of biosurfactant production by quorum sensing was examined in this
study, it is possible that other virulence factors, such as pectic enzyme production, are
also controlled by quorum sensing as in other pathogenic bacteria. By blocking the
quorum sensing system, the pathogenic P. fluorescens that use this mechanism to
control virulence could potentially be rendered avirulent. In greenhouse pathogenicity
tests, a quorum sensing signal-degrading bacterium, Bacillus sp. A24, was evaluated for
biocontrol of head rot disease caused by P. fluorescens 5064 on broccoli. However, the
Bacillus sp. A24 showed only limited control effects, despite its strong quorum sensing
signal-degrading ability towards the pathogen in vitro. A subsequent test proved that
Bacillus sp. A24 is a surfactant producer itself and this could explain its ineffectiveness
in disease control.
When screening the quorum sensing signals of the 35 biosurfactant mutants, mutant
6418 was found to produce a potent antibiotic-like compound. This was identified by
thin-layer chromatography as pyrrolnitrin. Unlike wild-type P. fluorescens 5064,
mutant 6418 has lost its ability to produce virulence factors and is thus non-pathogenic.
It was therefore of interest to determine if mutant 6418 could be used as a biocontrol
agent to control broccoli head rot disease. In greenhouse pathogenicity tests, mutant
6418 significantly reduced disease by 41 %.
The practical application of this research to bacterial disease control – via the
manipulation of quorum sensing to inhibit virulence gene expression – is 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
Regulation of biosurfactant production by quorum sensing in Pseudomonas fluorescens 5064, the cause of broccoli head rot disease
No full textBroccoli head rot is a destructive disease found in most broccoli production areas. The main pathogen is the bacterium Pseudomonas fluorescens. P. fluorescens 5064, which was first isolated from an infected broccoli head in SE Scotland, produces biosurfactants that are important for bacterial establishment on the plant surface prior to causing disease in broccoli. Preliminary experiments performed in this study showed that biosurfactant production in P. fluorescens 5064 was cell density dependent, which is a typical characteristic of the quorum sensing mechanism. Quorum sensing is a bacterial communication mechanism, which controls a number of key processes in growth, reproduction and virulence via signalling molecules (quorum sensing signal) in many gram-negative bacteria. One aim of this study was to determine if biosurfactant production in P. fluorescens 5064 is controlled via quorum sensing. To do this, 35 surfactant-minus Tn5 mutants of P. fluorescens 5064 were screened for their abilities to produce a quorum sensing signal. Six of these biosurfactant-deficient mutants showed a large reduction in quorum sensing signal production. In one mutant 6423, which contains a single Tn5 insertion, the production of the quorum sensing signal was almost eliminated. Addition of quorum sensing signal, either synthetic or extracted from wild type P. fluorescens 5064, was able to restore biosurfactant production in mutant 6423. This strongly suggests that quorum sensing regulates biosurfactant production in P. fluorescens 5064. Attempts were made to clone and sequence the Tn5 disrupted gene in mutant 6423, but the identity of the gene remains inconclusive. The quorum sensing signal in wild type P. fluorescens 5064 was identified in this study by High Pressure Liquid Chromatography and Mass Spectrometry as N-3-hydroxyoctanoyl-homoserine lactone, which has been shown by other researchers to be present in P. fluorescens strain 2-79, but not in the strains F113, 7-14 and NCIMB 10586. The discovery that biosurfactant production in P. fluorescens 5064 is regulated by quorum sensing opens up a possibility for novel control of broccoli head rot. Although only the control of biosurfactant production by quorum sensing was examined in this study, it is possible that other virulence factors, such as pectic enzyme production, are also controlled by quorum sensing as in other pathogenic bacteria. By blocking the quorum sensing system, the pathogenic P. fluorescens that use this mechanism to control virulence could potentially be rendered avirulent. In greenhouse pathogenicity tests, a quorum sensing signal-degrading bacterium, Bacillus sp. A24, was evaluated for biocontrol of head rot disease caused by P. fluorescens 5064 on broccoli. However, the Bacillus sp. A24 showed only limited control effects, despite its strong quorum sensing signal-degrading ability towards the pathogen in vitro. A subsequent test proved that Bacillus sp. A24 is a surfactant producer itself and this could explain its ineffectiveness in disease control. When screening the quorum sensing signals of the 35 biosurfactant mutants, mutant 6418 was found to produce a potent antibiotic-like compound. This was identified by thin-layer chromatography as pyrrolnitrin. Unlike wild-type P. fluorescens 5064, mutant 6418 has lost its ability to produce virulence factors and is thus non-pathogenic. It was therefore of interest to determine if mutant 6418 could be used as a biocontrol agent to control broccoli head rot disease. In greenhouse pathogenicity tests, mutant 6418 significantly reduced disease by 41 %. The practical application of this research to bacterial disease control – via the manipulation of quorum sensing to inhibit virulence gene expression – is discussed.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
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