1,721,307 research outputs found
The systematic status of the lagoon periwinkle, <i>Littorina tenebrosa</i>
No full textEight samples of Littorina tenebrosa and L. saxatilis (Mollusca: Gastropoda) from Ireland and Britain, including pairs of each form from two locations in Ireland, were screened for genetic variation at 12 polymorphic enzyme loci using starch gel electrophoresis. Levels of polymorphism and heterozygosity were similar in L. tenebrosa and L. saxatilis, apart from a sample of L. tenebrosa from Britain which was less polymorphic than the Irish samples. No alleles were found to be unique to either form. Phylogenetic analysis using UPGMA showed that L. saxatilis and L. tenebrosa populations clustered as a monophyletic group. Nevertheless, the mean genetic distance between parapatric populations of L. saxatilis and L. tenebrosa (D=0.076) was similar to the mean for allopatric populations of either species (D=0.080). This indicates that there is a barrier to gene flow between the two forms Despite this, L. tenebrosa does not merit specific status since populations of this snail do not cluster as a distinct group, separate from L. saxatilis populations
Exploitation of glycosylation in enveloped virus pathobiology
No full textGlycosylation is a ubiquitous post-translational modification responsible for a multitude of crucial biological roles. As obligate parasites, viruses exploit host-cell machinery to glycosylate their own proteins during replication. Viral envelope proteins from a variety of human pathogens including HIV-1, influenza virus, Lassa virus, SARS, Zika virus, dengue virus, and Ebola virus have evolved to be extensively glycosylated. These host-cell derived glycans facilitate diverse structural and functional roles during the viral life-cycle, ranging from immune evasion by glycan shielding to enhancement of immune cell infection. In this review, we highlight the imperative and auxiliary roles glycans play, and how specific oligosaccharide structures facilitate these functions during viral pathogenesis. We discuss the growing efforts to exploit viral glycobiology in the development of anti-viral vaccines and therapies.</p
Structure and immune recognition of the HIV glycan shield
No full textVaccine design efforts against the human immunodeficiency virus (HIV)have been greatly stimulated by the observation that many infected patients eventually develop highly potent broadly neutralizing antibodies (bnAbs).Importantly, these bnAbs have evolved to recognize not only the two protein components of the viral envelope protein (Env) but also the numerous glycans that form a protective barrier on the Env protein. Because Env is heavily glycosylated compared to host glycoproteins, the glycans have be- come targets for the antibody response. Therefore, considerable efforts have been made in developing and validating biophysical methods to elucidate the complex structure of the Env-spike glycoprotein, with its combination of glycan and protein epitopes. We illustrate here how the application of robust biophysical methods have transformed our understanding of the structure and function of the HIV Env spike and stimulated innovation in vaccine design strategies that takes into account the essential glycan components
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
HOW TCRS BIND MHCS, PEPTIDES, AND CORECEPTORS
No full textSince the first crystal structure deteminations of alpha beta T cell receptors (TCRs) bound to class I MHC-peptide (pMHC) antigens in 1996, a sizable database of 24 class I and class II TCR/pMHC complexes has been accumulated that now defines a substantial degree of structural variability in TCR/pMHC recognition. Recent determination of free and bound gamma delta TCR structures has enabled comparisons of the modes of antigen recognition by alpha beta and gamma delta T cells and antibodies. Crystal structures of TCR accessory (CD4, CD8) and coreceptor molecules (CD3 epsilon delta, CD3 epsilon gamma) have further advanced our structural understanding of most of the components that constitute the TCR signaling complex. Despite all these efforts, the structural basis for MHC restriction and signaling remains elusive as no structural features that define a common binding mode or signaling mechanism have yet been gleaned from the current set of TCR/pMHC complexes. Notwithstanding, the impressive array of self, foreign (microbial), and autoimmune TCR complexes have uncovered the diverse ways in which antigens can be specifically recognized by TCRs.NCI NIH HHS [CA-58896]; NIAID NIH HHS [AI-42266
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
Combined pseudo-merohedral twinning, non-crystallographic symmetry and pseudo-translation in a monoclinic crystal form of the gamma delta T-cell ligand T10
No full textT10 is a non-classical class Ib-like major histocompatibility complex (MHC) cell-surface antigen which binds directly to certain gammadelta T-cell receptors in the absence of any exogenous and endogenous ligands, such as peculiar lipids or glycolipids. The crystal structure at 2.5 Angstrom resolution of murine T10 was determined by molecular replacement using data from an almost perfectly twinned monoclinic crystal. The space group is P2(1), with unit-cell parameters a=78.2, b=70.0, c=139.2 Angstrom, beta=106.8degrees. Self-rotation function analysis and various intensity statistics revealed the presence of pseudo-merohedral twinning, but these tests underestimated the true twin fraction of alphasimilar or equal to0.46. Native Patterson analyses pointed to the presence of pseudo-translation among the four molecules present in the asymmetric unit. Data analysis, structure determination and model refinement are discussed.NCI NIH HHS [CA58896
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
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