102,464 research outputs found
Structural insights into the membrane-extracted dimeric form of the ATPase TraB from the Escherichia coli pKM101 conjugation system
No full textBackground: Type IV secretion (T4S) systems are involved in secretion of virulence factors such as toxins or transforming molecules, or bacterial conjugation. T4S systems are composed of 12 proteins named VirB1-B11 and VirD4. Among them, three ATPases are involved in the assembly of the T4S system and/or provide energy for substrate transfer, VirB4, VirB11 and VirD4. The X-ray crystal structures of VirB11 and VirD4 have already been solved but VirB4 has proven to be reluctant to any structural investigation so far. Results: Here, we have used small-angle X-ray scattering to obtain the first structural models for the membrane-extracted, dimeric form of the TraB protein, the VirB4 homolog encoded by the E. coli pKM101 plasmid, and for the monomeric soluble form of the LvhB4 protein, the VirB4 homolog of the T4S system encoded by the Legionella pneumophila lvh operon. We have obtained the low resolution structures of the full-length TraB and of its N- and C-terminal halves. From these SAXS models, we derive the internal organisation of TraB. We also show that the two TraB N- and C-terminal domains are independently involved in the dimerisation of the full-length protein. Conclusions: These models provide the first structural insights into the architecture of VirB4 proteins. In particular, our results highlight the modular arrangement and functional relevance of the dimeric-membrane-bound form of TraB
Structure of human alpha-thrombin Y225I mutant bound to D-PHE-PRO-ARG-chloromethylketone
No full textStructure of human alpha-thrombin Y225P mutant bound to D-PHE-PRO-ARG-chloromethylketone
No full textAlteration of lead-glazed ware and amphorae from shipwreacks in the Black Sea (Ukraine).
No full textCommon scab and its control in seed-potato crops
No full textIn the Netherlands common scab of the potato is usually caused by Streptomyces scabies (Thaxter) Waksman et Henrici, following Corbaz's description, and rarely by other Streptomyces species. Variation in morphological and other characteristics could not be correlated with lesion types and non-pathogenic S.scabies strains do exist. Three scab types were described, viz. 'normal', 'superficial' and 'russet'. Studies of scab lesion anatomy and reaction to external conditions suggested that superficial and normal scab isolates mainly differ in virulence. The russet scab type does differ in symptom expression and anatomy, in reaction to temperature and moisture and in attacking the root system, but our isolates do belong to S.scabies.After infection the main pathway of the mycelium. seems to be intercellular, and, towards the interior of the lesion the mycelium spreads in cell walls, but is very difficult to find because it stains poorly.Chemical control of scab offers few prospects in the Netherlands. Only PCNB (pentachloronitrobenzene, quintozene) has been applied with some success, but has the disadvantages of yield loss, delay in the expression of virus symptoms and offflavour in tubers for eating. Other chemicals were not sufficiently active to control scab when applied at economic rates.Introduction of antagonists into soil as a measure of scab control proved to be impossible without further far reaching agricultural measures and is economically unattractive. Crop rotations and application of green manures also showed little effect on scab incidence.Irrigation during four weeks after tuber formation starts, proved to be the most effective way of controlling scab. The effect of irrigation on the microbial population of the soil was investigated and irrigation was shown to shift the ratio of pathogenic actinomycetes to bacteria in an unfavourable way for S. scabies.</em
Structure of human alpha-thrombin Y225F mutant bound to D-PHE-PRO-ARG-chloromethylketone
No full textLipman, Jacob G.
No full textThis project was assisted by a grant from the New Jersey Historical Commission, a division of the Department of State.Names of other Rutgers people: Carl R. Fellers, Herman J. Levine, James B. Scarr, Allen G. Waller, Joseph R. Neller, Robert F. Poole, S. A. Waksman, John Phillips Street '8
Bibliographie Hilarion G. Petzold 1958 – 2009 mit Anhang als Einführung
No full textDieses Archiv enthält die Gesamtbibliographie der Werke des Autors nebst einiger Texte „Über H. G. Petzold“ im Schlussteil der Bibliographie sowie einen Anhang mit einer Einführung in die Architektur des Werkes in seinem wissenslogischen Aufbau als Ausarbeitung seines „Tree of Science Modells“ (2007).This archive contains the complete bibliography of the author and some texts about H. G. Petzold, moreover an epilogue with an introduction to the architecture of the works in its epistemological structure and composition and as an elaborations of Petzold’s „Tree of Science Modell (2007).https://www.fpi-publikation.de/polyloge/01-2009-petzold-h-g-gesamtbibliographie-h-g-petzold-1958-2009-updating-november2009/peerReviewedpublishedVersio
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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
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