8,199 research outputs found
Caulobacter crescentus adapts to phosphate starvation by synthesizing anionic glycoglycerolipids and a novel glycosphingolipid
No full textCaulobacter crescentus adapts to phosphate starvation by elongating its cell body and a polar stalk structure. The stalk is an extension of the Gram-negative envelope containing inner and outer membranes as well as a peptidoglycan cell wall. Cellular elongation requires a 6- to 7-fold increase in membrane synthesis, yet phosphate limitation would preclude the incorporation of additional phospholipids. In the place of phospholipids, C. crescentus can synthesize several glycolipid species, including a novel glycosphingolipid (GSL-2). While glycosphingolipids are ubiquitous in eukaryotes, the presence of GSL-2 in C. crescentus is surprising since GSLs had previously been found only in Sphingomonas species, in which they play a role in outer membrane integrity. In this paper, we identify three proteins required for GSL-2 synthesis: CcbF catalyzes the first step in ceramide synthesis, while Sgt1 and Sgt2 sequentially glycosylate ceramides to produce GSL-2. Unlike in Sphingomonas, GSLs are nonessential in C. crescentus; however, the presence of ceramides does contribute to phage resistance and susceptibility to the cationic antimicrobial peptide polymyxin B. The identification of a novel lipid species specifically produced upon phosphate starvation suggests that bacteria may be able to synthesize a wider variety of lipids in response to stresses than previously observed. Uncovering these lipids and their functional relevance will provide greater insight into microbial physiology and environmental adaptation.Peer reviewe
tritrophic-dispersal-model: Code used for creating figures for "Non-hierarchical dispersal promotes stability and resilience in a tri-trophic metacommunity"
No full text<p>This is the commented code used for creating figures for the paper. Any questions regarding the code should be directed to the corresponding author and repository owner (Eric Pedersen). </p>
Q & A - Eric Davidson
No full textEric Davidson graduated from the University of Pennsylvania in 1954 and received his PhD from Rockefeller University in 1963. He remained at Rockefeller until 1971 when he moved to Caltech in Pasadena, California. He was elected to the U.S. National Academy of Sciences in 1985, and is at present Norman Chandler Professor of Cell Biology in the Division of Biology, Caltech. He is the author of 5 books and over 400 papers on developmental gene regulation and evolution of genomic programs for development. For the last decade his work has focused on theory and operation of developmental gene regulatory networks
Perspective: Adhesion Mediated Signal Transduction in Bacterial Pathogens
No full textDuring the infection process, pathogenic bacteria undergo large-scale transcriptional changes to promote virulence and increase intrahost survival. While much of this reprogramming occurs in response to changes in chemical environment, such as nutrient availability and pH, there is increasing evidence that adhesion to host-tissue can also trigger signal transduction pathways resulting in differential gene expression. Determining the molecular mechanisms of adhesion-mediated signaling requires disentangling the contributions of chemical and mechanical stimuli. Here we highlight recent work demonstrating that surface attachment drives a transcriptional response in bacterial pathogens, including uropathogenic Escherichia coli (E. coli), and discuss the complexity of experimental design when dissecting the specific role of adhesion-mediated signaling during infection.Peer reviewe
Eric C. Lincoln, Professor of Sociology and Religion, 1971
No full textThis is an interview with Eric C. Lincoln. Eric was a Professor of Sociology and religion, Union Theological Seminary and author of many books and articles on Negro history. In this recording the contributors discuss local memphis politics, sociology, and race relations compared to that of other cities in the South and the rest of the country
10th C. Eric Lincoln Lecture Series, 1992
No full textPart of the 10th anniversary of the C. Eric Lincoln lecture series Dr. Love Henry Whelchel moderates a panel of scholars. The panel includes Dr. C. Eric Lincoln, Dr. Jacquelyn Grant, and Dr. John Hope Franklin. The panel discusses the life of George Washington Williams (author of History of the Negro Race in America). The discussion includes issues related to Womanist theology, Islamic religion, sociology, religion and history.The Atlanta University Center Robert W. Woodruff Library acknowledges the generous support of the National Endowment for Humanities - Humanities Collections and Reference Resources Implementation Project Grant in supporting the processing and digitization of a number of its major archival collections as part of the project: Spreading the Word: Expanding Access to African American Religious Archival Collections at the Atlanta University Center Robert W. Woodruff Library
Differential modes of crosslinking establish spatially distinct regions of peptidoglycan in Caulobacter crescentus
No full textThe diversity of cell shapes across the bacterial kingdom reflects evolutionary pressures that have produced physiologically important morphologies. While efforts have been made to understand the regulation of some prototypical cell morphologies such as that of rod-shaped Escherichia coli, little is known about most cell shapes. For Caulobacter crescentus, polar stalk synthesis is tied to its dimorphic life cycle, and stalk elongation is regulated by phosphate availability. Based on the previous observation that C. crescentus stalks are lysozyme-resistant, we compared the composition of the peptidoglycan cell wall of stalks and cell bodies and identified key differences in peptidoglycan crosslinking. Cell-body peptidoglycan contained primarily DD-crosslinks between meso-diaminopimelic acid and D-alanine residues, whereas stalk peptidoglycan had more LD-transpeptidation (meso-diaminopimelic acid-meso-diaminopimelic acid), mediated by LdtD. We determined that ldtD is dispensable for stalk elongation; rather, stalk LD-transpeptidation reflects an aging process associated with low peptidoglycan turnover in the stalk. We also found that lysozyme resistance is a structural consequence of LD-crosslinking. Despite no obvious selection pressure for LD-crosslinking or lysozyme resistance in C. crescentus, the correlation between these two properties was maintained in other organisms, suggesting that DAP-DAP crosslinking may be a general mechanism for regulating bacterial sensitivity to lysozyme.Peer reviewe
Consistency between descriptors, author-supported keywords and tags in the ERIC and Mendeley databases
No full textThe purpose of this study was to identify the language consistency between indexers, authors and taggers in the ERIC and Mendeley databases. This survey was conducted using content analysis methods and techniques to evaluate the language consistency between indexers, authors and taggers in the ERIC and Mendeley databases and also to determine common keywords. The sample for this study was comprised of top twenty journals in the field of Educational Research based on the Journal Citation Reports (JCR) of Web of Science, indexed in the ERIC database in 2014. Finally 499 articles published in the above-mentioned journals in 2014 were chosen as the sample base for the dataset. Note that only articles with author-supported keywords, indexed in the ERIC database and also tagged in the Mendeley database from January 2014 to August 2016 were eligible to be assessed. Descriptors assigned to the articles on the ERIC database and tags associated to the articles on the Mendeley database for the period from January 2014 to August 2016 were extracted. Also author-assigned keywords assigned to all 499 articles were collected. Finally we created a software based on object-oriented programming (OOP) in C++ to analyze the search results. Descriptive statistics and measures, and thesaural term comparison show that there are important differences in the context of keywords from the three groups.
This study demonstrated that there were differences between the tagger, author and professional indexer views of the words used as tags, descriptors, or author-assigned keywords. The results showed that the consistency between the author-supported keywords and user tags of the 499 articles in the Mendeley was 15 percent; while the consistency between descriptors designated to the articles in the ERIC database and user tags associated to the articles on the Mendeley were three percent. On the other hand, the consistency between descriptors assigned to the articles in the ERIC database and the author-assigned keywords were 4 percent. Finally, the language consistency between the three above-mentioned groups was 1.1 percent. Also note that the presence of descriptors in the ERIC thesaurus was 34 percent, which were more than the author-supported keywords and tags.
The findings showed that the consistency between the keywords used by authors and taggers were more than the keywords chosen by indexers and authors, and by indexers and taggers. This means that three sides of the information representation triangle, i.e., indexer, author and tagger are unfamiliar with each other’s language. It is worth noting that tags are useful supplements to controlled vocabularies, since the former provide a means for social organization of knowledge outside the framework of the latter. The low consistency between tags and descriptors in this research indicates that Mendeley users do not use the same terminology as subject specialists who maintain descriptors in the ERIC thesaurus. Further research involving semantic analysis of Mendeley tags may reveal an emerging vocabulary suitable for inclusion in the ERIC thesaurus as a controlled vocabulary
"Best of C. Eric Lincoln"
No full textThis recording features several musical selections written by C. Eric Lincoln. Some of the selections include Cassius McCool, When Love Was New, and Carolina.The Atlanta University Center Robert W. Woodruff Library acknowledges the generous support of the National Endowment for Humanities - Humanities Collections and Reference Resources Implementation Project Grant in supporting the processing and digitization of a number of its major archival collections as part of the project: Spreading the Word: Expanding Access to African American Religious Archival Collections at the Atlanta University Center Robert W. Woodruff Library.</em
Dr. Eric Yellin – Faculty Author Interview
No full textDr. Eric Yellin, Associate Professor of History and American Studies discusses his new book, Racism in the Nation’s Service: Government Workers and the Color Line in Woodrow Wilson’s America, published recently by the University of North Carolina Press. In this book, Dr. Yellin argues that President Wilson’s administration successfully segregated the federal government in the age of progressive politics. He investigates how the enactment of the segregation policy imposed a color line on American opportunity and implicated Washington in the economic limitation of African Americans for decades to com
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