1,720,953 research outputs found
Cytochrome P-450 related to insecticide resistance in Drosophila Melanogaster
No full textThe cytochrome P-450-dependent mixed function oxidase (MFC) system in insects appears to be particularly important in insecticide resistance. Because of the multiplicity of P-450 isozymes and their overlapping substrate specificities, qualitative and quantitative variations in the different forms of P-450 can influence both insecticide metabolism and normal metabolic processes such as hormone and pheromone biosynthesis and feeding habits. Resistance to various insecticides in Drosophila has been directly associated with increased or unique MFO activities.
The Drosophila strains Hikone-R(BG) and 91-R were originally selected for resistance to the organochlorine insecticide DDT and were shown in these experiments to also be cross-resistant to malathion, an organophosphate. The Hikone-R(BG), 91-R, and MH-II strains are all cross-resistant to various classes of insecticides, and all possess a unique microsomal protein band with a molecular mass of approximately 56 kDa, designated P-450-B, that is not discernible in the susceptible Drosophila strains Oregon-R, 91-C and Canton-S. All Drosophila strains examined contain an ubiquitous subset of P-450 with a molecular mass of 59 kDa identified as P-450-A. The Hikone-R(BG) and 91-R strains had higher total P-450 contents, and much greater (30 to 60-fold) N-nitrosodimethylamine (NDMA) demethylase activities than their susceptible counterparts Oregon-R and 91-C.
P-450-A and P-450-B were purified from Oregon-R and Hikone-R(BG) by sequential chromatography on octylamino-agarose, DEAE-cellulose, and hydroxyapatite. Purified Drosophila P-450-A and P-450-B had specific activities from 6-9 nmol P-450/mg protein and exhibited molecular weights exactly corresponding to P-450-A and P-450-B in microsomes.
Drosophila NADPH-cytochrome P-450 reductase was purified from Oregon-R by affinity chromatography on NADP-agarose and had a molecular weight of 65 kDa. Purified NADPH-cytochrome P-450 reductase was capable of reducing purified P-450 in vitro.
Analysis of purified P-450-A and P-450-B by isoelectric focusing and 2-D electrophoresis showed that P-450-A is composed of at least five forms with different isoelectric points while P-450-B contains a minimum of two different forms.
Purified preparations containing both P-450-A and P-450-B exhibited catalytic activity in a reconstituted system with phospholipid, NADPH-cytochrome P-450 reductase, and 7-ethoxycoumarin as substrate. Purified P-450-A, partially purified P-450 preparations, or solubilized microsomes did not metabolize 7-ethoxycoumarin or benzo(a)pyrene in the reconstituted system.
P-450-specific MoAbs were produced that recognized solubilized P-450 epitopes in solid-phase RIA and ELISA techniques and bound to denatured P-450 epitopes in immunoblots. One of these MoAbs, 433-8-1d was specific for P-450-B, while another, 433-13-2e, recognized P-450-A-specific epitopes.
Neither MoAb 433-8-1d or 433-13-2e could inhibit P-450-dependent NDMA-demethylase activity, but immune serum from the mouse utilized to produce these hybridomas suppressed over 50% of this activity compared to control levels. Purified MoAb 433-8-1d conjugated to Sepharose beads could not selectively remove NDMA-demethylase activity from microsomes.
P-450-A and P-450-B specific MoAbs were used to examine the expression of immunoreactive P-450 in insecticide resistant and sensitive Drosophila strains. Large amounts of P-450-B were detected in immunoblotting experiments using microsomes from resistant Hikone-R(BG), 91-R, and MH-II strains. Trace amounts of P-450-B were found in the susceptible Oregon-R, 91-C, and Canton-S strains. P-450-A constituted the bulk of the immunoreactive P-450 in susceptible strains, but P-450-B was the major P-450 form in the resistant strains. Immunoreactive P-450-B levels were 10 to 20-fold greater in resistant than susceptible strains. The expression of significant amounts of immunoreactive P-450-B required a positive second chromosome derived from a resistant strain and this P-450-B level was increased in strains containing both positive chromosomes II and III.
MoAbs to Drosophila P-450 cross-reacted with microsomes and partially purified preparations from the resistant Rutgers, and susceptible CSMA housefly strains in immunoblots, and the P-450-B-specific MoAb 433-8-1d bound microsomes from Southern armyworms in RIA and ELISA experiments. MoAb 433-8-1d also reacted with microsomal proteins prepared from both normal rat liver and animals induced with ethanol or phenobarbital while MoAb 13-2e did not recognize any rat liver proteins.
Cytochrome P-450-B expression related to insecticide resistance in Drosophila has been extensively characterized by biochemical, genetic, and immunochemical methods. The reagents necessary to expand this analysis to include the molecular biology of P-450 expression and P-450-related resistance are now available and the system is ready to be exploited to its fullest potential
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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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