1,720,960 research outputs found
Reactions of All Escherichia coli Lytic Transglycosylases with Bacterial Cell Wall
No full textThe reactions of all seven Escherichia coli lytic transglycosylases with purified bacterial sacculus are characterized in a quantitative manner. These reactions, which initiate recycling of the bacterial cell wall, exhibit significant redundancy in the activities of these enzymes along with some complementarity. These discoveries underscore the importance of the functions of these enzymes for recycling of the cell wall.Fil: Lee, Mijoon. University Of Notre Dame-indiana; Estados UnidosFil: Hesek, Dusan. University Of Notre Dame-indiana; Estados UnidosFil: Llarrull, Leticia Irene. University Of Notre Dame-indiana; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Lastochkin, Elena. University Of Notre Dame-indiana; Estados UnidosFil: Pi, Hualiang. University Of Notre Dame-indiana; Estados UnidosFil: Boggess, Bill. University Of Notre Dame-indiana; Estados UnidosFil: Mobashery, Shahriar. University Of Notre Dame-indiana; Estados Unido
A Central Role for Magnesium Homeostasis during Adaptation to Osmotic Stress
No full textEnvironments with high concentrations of salt or other solutes impose an osmotic stress on cells, ultimately limiting viability by dehydration of the cytosol. A very common cellular response to high osmolarity is to immediately import high levels of potassium ion (K + ), which helps prevent dehydration and allows time for the import or synthesis of biocompatible solutes that allow a resumption of growth
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
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
IRON HOMEOSTATIC SYSTEMS AND IRON LIMITATION RESPONSES IN BACTERIA
Full text linkIron is required for most bacteria but its bioavailability is extremely low. So iron acquisition has become a major challenge in bacterial physiology. Iron acquisition includes uptake systems for elemental iron, ferric citrate, and various ferric-siderophore complexes. Iron-mediated regulation takes place at multi-levels: transcriptional, post-transcriptional, and translational. These regulatory systems enable bacteria to achieve homeostatic balance with iron (Chapter 1). Iron is also toxic at elevated levels. Recent results revealed that Fe(II) exporters play a crucial role in preventing iron overload. These include P1B-type ATPases, cation diffusion facilitators, major facilitator superfamily proteins, and membrane bound ferritin-like proteins (Chapter 2). Among these systems, FrvA is a virulence factor in Listeria monocytogenes. The characterization of FrvA as an Fe(II) efflux transporter provides the first direct evidence linking iron efflux to bacterial pathogenesis. Furthermore, FrvA is a high-affinity Fe(II) exporter and its expression imposes severe iron starvation in Bacillus subtilis (Chapter 3). Thus it has been employed as an inducible genetic tool to study iron limitation responses. Iron acquisition and homeostasis systems need to be tightly regulated to ensure sufficiency for biological functions but not excess that would trigger intoxication. The ferric uptake regulator (Fur) monitors intracellular iron levels and plays a central role in maintaining bacterial iron homeostasis. However, it is unclear whether Fur-regulated genes are derepressed coordinately or in a sequential manner upon iron starvation. Here the iron limitation responses were characterized in B. subtilis (Chapter 4). In particular, the Fur-regulated genes are induced in three sequential waves in response to iron depletion: (i) cells increase their capacity for iron import from common sources of iron in the environment; (ii) cells turn on high-affinity siderophore-mediated import systems to scavenge iron; (iii) as iron levels decrease further, cells activate an iron-sparing response to remodel their proteome. This graded response correlates with in vivo occupancy of Fur protein and can be explained, at least in part, as a direct effect of differences in operator binding affinity of Fur protein. These results provide insights into the distinct roles of Fur-target genes and contribute to our understanding of bacterial metalloregulatory systems
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