1,720,982 research outputs found
Dissecting different modules of cytochrome c maturation in Rhodobacter capsulatus
No full textCytochrome c maturation (CCM) in Gram-negative bacteria involves at least ten membrane-bound components (CcmABCDEFGHI and CcdA) and the oxidative protein folding pathway (DsbA/DsbB). These components are distributed among three distinct modules: thioredox-loop, heme delivery and heme ligation. In this study, first we focused on the thioredox-loop, by which the heme binding motif CXXCH within the apocyt c is believed to be initially oxidized by DsbA/DsbB and then reduced by the CcdA/CcmG and CcmH. We have previously reported that the cyt c deficiency of CcdA-null mutants can be bypassed by mutations in DsbA and DsbB. Here, we showed that CcdA and CcmG are not essential for the formation of cyt c, but important for the efficiency of CCM in the absence of DsbA. The respective double and triple mutants can produce cyts c, albeit at significantly lower levels, and grow photosynthetically on media supplemented with thiol-reactive reagents. Moreover, CcmG without active site cysteines can facilitate cyt c production in these mutants, suggesting a distinct and previously undefined role of CcmG in addition to its thioredoxin function. Second, we concentrated on the physical interactions among CCM components and on the putative CcmHIF heme ligation complex which catalyzes the thioether bond formation between the heme and the apocyt c. Our co-purification results indicate that CcmH and CcmF form the core complex of CCM. Furthermore, CcmI is in the complex via interaction with CcmH. Gel filtration data shows that CcmF, CcmH and CcmI form a protein complex of about 900-1000 kDa with yet unknown stoichiometry. We report for the first time a CcmHIF containing bacterial heme lyase complex in R. capsulatus. Last, since DsbA-null mutants of R. capsulatus are defective for respiratory growth on enriched medium, we investigated the basis underlying this phenotype by proteomics and molecular biological approaches. We showed that in the absence of DsbA, not only overabundance of major periplasmic protease DegP rendered respiratory growth defective, but also lack of DegP was lethal. Finally, phylogenetic analysis identified two related but distinct bacterial extracytoplasmic protease families
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
Investigating the role of regulation in resilience of microbial communities under fluctuating environmental conditions
Get PDFGene regulatory networks are thought to be a vital contribution to microbial resilience in a fluctuating environment. Known gene regulatory networks were utilized to elucidate how the sulfate-reducing bacteria Desulfovibro vulgaris regulates its survival in its relative fluctuating environment while evolving to form a symbiotic relationship with the archaeal organism, Methanococcus maripaludis. By using transposon gene knockout methods to form transcription factor mutants in Desulfovibro vulgaris, the effect on the regulatory network is observed when the bacteria is co-cultured with Methanococcus maripaludis. Transferring methods to simulate fluctuating environments were used to induce transcription of regulatory genes. To measure the extent of the relative gene effects, growth curves were made and sampling of RNA was done every five transfers to measure transcription levels. What was found was that cultures generally collapse after 3-7 transfers. After extractions and sequencing of mutant strains\u27 RNA transcripts, the transcription level of relative genes will give insight to which genes are involved in regulation of survival and were active during stress responses
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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