1,723,487 research outputs found
Mechanisms of greater cardiomyocytes functions on conductive nanoengineered composites for cardiovascular applications. [Corrigendum]
No full textStout DA, Yoo J, Noemi Santiago-Miranda AN, Webster TJ International Journal of Nanomedicine 2012,7:5653–5669An author was incorrectly listed as Noemi Santiago-Miranda A, but should be listed as:Santiago-Miranda AN.In addition, the correct spelling for Santiago-Miranda AN institution affiliation is Mayagüez instead of Mayagües.Read the original articl
Bacteriophage SP6 RNA polymerase mutants with altered termination efficiency and elongation processivity
No full textAn Escherichia coli strain containing two plasmids was developed for in vivo isolation of the phage SP6 RNA polymerase mutants. It was developed to isolate mutants with increased proficiency of termination at the SP6 terminator and/or with reduced elongation processivity. Mutations were randomly introduced into an N-terminal third of the polymerase gene that was placed under a Inc promoter in one plasmid. In the other plasmid, a promoter-lacking lacZ gene modified for reduced translation efficiency was placed downstream of a tandem pair of the SP6 terminator located downstream of an SP6 promoter-chloramphenicol acetyltransferase gene. Termination-up mutants were selected in vivo as they rendered LacZ activity level lower than the wild-type, without reducing chloramphenicol resistance substantially. Three such mutants (M15L, M15S, and D117G) were purified, and their termination efficiencies were measured in vitro at two different intrinsic termination signals in the E. coli rrnB terminator tl that are different in requiring RNA hairpin formation. All three mutations enhanced termination efficiencies in vitro at the SP6 terminator and the upstream signal of rnnB tl, but reduced the efficiency at the downstream signal of it. All the mutations reduced elongation processivity, as the mutants produced much less amounts of large transcripts (2.1 kb) than the wild-type but the similar amounts of small transcripts (up to 670 nt). Thus, the mutations, all reducing elongation processivity of the polymerase, exhibited opposite effects on the two types of intrinsic termination signals, suggesting that the two mechanisms involve different interactions with the phage RNA polymerase. Published by Elsevier Science B.V
The first stable platinum(II) complex of o-carborane-linked bipyridine as a potential BNCT reagent
No full textThe authors gratefully acknowledge
financial supports from the CMDS and the BK 21 Project
Variation of in vivo efficiency of the bacteriophage T7 terminator depending on terminator-upstream sequences
No full textThe 40-kb linear genome of bacteriophage T7 contains only one terminator T phi, for the phage T7 RNA polymerase that is located between genes 10 and 11, Its in vitro termination efficiency has been previously found to vary upon any sequence within a transcription unit [Lee, J. T., Kim, H., Moon, K;., Kim, S., and Kang, C. (1991) Mel. Cells 1, 203-209]. In order to see if this variation takes place also in vivo, termination efficiencies within E. coli cells of the same terminator in the three different transcription units were measured in this study. The three recombinant plasmids, pNNTcat, pSNTcat, and pSSTcat, are different only in promoter-proximal, terminator distal sequence, and/or terminator-proximal upstream sequence. They have shown substantially different in vitro termination efficiencies. In vivo termination efficiencies were measured by two different methods. One method was to compare the expression product levels of a terminator-downstream caf gene (CAT activity) in the presence and absence of the terminator. The other was to compare the RNA levels of terminator-upstream and -downstream DNA. The in vivo termination efficiencies were different in three different plasmids when measured by RNA levels: levels: 97% in pNNTcat, 79% in pSNTcat, and 52% in pSSTcat (the latter tao plasmids showed significantly lower values when measured by protein levels). These in vivo efficiencies were substantially higher than the previously measured in vitro values (77%, 35%, and 17%, respectively). Nevertheless, the order of termination efficiency among the three plasmids was the same within E. call cells as in vitro: pNNTcat > pSNTcat > pSSTcat. Thus, termination efficiency of phage T7 RNA polymerase at the T7 terminator T phi varies upon both terminator-proximal and -distal upstream sequences not only in vitro, but also within E. coli cells
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
The effect of structural holes on the corporate performance and Strategic alliances network in pharmaceutical industry
No full textOrthogonal nonnegative matrix tri-factorization for co-clustering: Multiplicative updates on Stiefel manifolds
No full textMatrix factorization-based methods become popular in dyadic data analysis, where a fundamental problem, for example, is to perform document clustering or co-clustering words and documents given a term-document matrix. Nonnegative matrix tri-factorization (NMTF) emerges as a promising tool for co-clustering, seeking a 3-factor decomposition X approximate to USVT with all factor matrices restricted to be nonnegative, i.e.. U >= 0.S >= 0, V >= 0. In this paper we develop multiplicative updates for orthogonal NMTF where X approximate to USVT is pursued with orthogonality constraints, (UU)-U-T = I. and (VV)-V-T = I, exploiting true gradients on Stiefel manifolds. Experiments on various document data sets demonstrate that our method works well for document clustering and is useful in revealing polysemous words via co-clustering words and documents. (C) 2010 Elsevier Ltd. All rights reserved.X1132sciessciahciscopu
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