1,720,982 research outputs found
Antimicrobial peptides in Urticina eques and Echinus esculentus. Isolation, characterisation, and structure-activity relationship studies
No full textBacterial resistance to antibiotics has become a serious global problem. Infections that once were easily cured with antibiotics have now become nearly impossible to treat. Thus, there is a desperate need for new antibacterial drugs. Antimicrobial peptides (AMPs) are a diverse group of compounds. Amongst their unique features are their ability to kill bacteria (often both Gram-positive and Gram-negative) as well as other microorganisms rapidly without toxicity to other cells. AMPs have been suggested as an option for treating bacterial infections where traditional antibiotics have little effect.
The overall aim of the study was to discover and characterise novel AMPs in Echinodermata and Cnidaria, and secondarily to map bioactivities, explore toxicity and perform structure-activity relationship studies.
The most potent AMPs were discovered via bioassay-guided purification in the edible sea urchin Echinus esculentus, killing bacteria at low µM-concentrations and fungi at somewhat higher concentrations. The AMPs were homologous to the centrocins and strongylocins of the green sea urchin Strongylocentrotus droebachiensis and were named EeCentrocins 1 and 2 (dimeric and with the antimicrobial activity located in the heavy chain), Ee4634 and EeStrongylocin 2. All AMPs were post-translationally modified on all Trp-residues with a bromine in the 6 position. Additional post-translational modifications involved C-terminal amidation on the light chains of EeCentrocins 1 and 2, N-terminal cyclic glutamate on EeCentrocin 2 and disulphide bonds on EeStrongylocin 2. None of the EeCentrocin HCs displayed toxicity to human erythrocytes. Structure-activity relationship studies on EeCentrocin 1 heavy chain (30 amino acids) led to a truncated 12-mer AMP where Asp8 and Asn12 were replaced with Ala and Lys respectively. The AMP displayed potent antimicrobial activities. Additionally, an Ala-scan was performed identifying the two Trp-residues as crucial for activity towards Gram-negative bacteria, whereas the anti-Gram-positive activity was more dependent on the Trp in position two.
An AMP in Urticina eques was named -AnmTx Ueq 12-1 (short name Ueg 12-1) and characterised. This AMP was antibacterial exclusively towards the Gram-positive Corynebacterium glutamicum at 50 µM concentrations. Ueq 12-1 was bifunctional as it potentiated the TRPA1 ion channel in addition to its antibacterial activity. Analgesic activity was furthermore demonstrated in vivo in rats where the peptide reduced licking behaviour on a hot-plate test. The primary sequence of Ueq 12-1 appeared non-homologous to any currently known peptides, but the 3D-structure was somewhat homologous to the defensins
Lab scale extraction of components from snow crab (Chionoecetes opilio) co-products, and estimation of processing costs based on a small-scale demonstration plant (Biotep)
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Observations from the Hydrolysis of the Green Sea Urchin (Strongylocentrotus droebachiensis)
Full text linkThere is a large amount of coproduct generated by the sea urchin fisheries around the world as well as a growing interest in removing large quantities of undersize and low value sea urchins from barren areas in the northern Atlantic and Pacific coasts as well as other areas around the world. The authors believe there is scope to develop a hydrolysate product from this and this study gives preliminary observations on the characteristics of hydrolysate from the sea urchin Strongylocentrotus droebachiensis. The biochemical composition for S. droebachiensis is moisture 64.1%, protein 3.4%, oil 0.9%, and ash 29.8%. Amino acid composition, molecular weight distribution, lipid-class, and fatty acid composition are also presented. The authors suggest a sensory-panel mapping be undertaken on future sea urchin hydrolysates. Possible uses for the hydrolysate are unclear at this stage but the combination of amino acids and the relatively high levels of glycine, aspartic acid, and glutamic acid should be further investigated
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
The value of creating plus-products - the Norwegian Marine Ingredients Industry
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