1,721,530 research outputs found
In vitro cytotoxicity of crustacean immunostimulants for lobster (Homarus gammarus) granulocytes demonstrated using the neutral red uptake assay
No full textThe neutral red uptake (NRU) cell viability assay was adapted for use with lobster Homarus gammarus (Linnaeus, 1758) granulocytes cultured in vitro. The assay was more sensitive than the conventional trypan blue exclusion assay and facilitated a higher sample throughput than subjective microscope-based assessments of cell viability. The NRU assay was demonstrated to have a linear response from 470 to at least 126 000 cells cm-2. It was used to investigate the acute cytotoxicity of 3 commercial and 2 candidate crustacean aquaculture immunostimulants on lobster granulocytes. All 5 stimulants had a cytotoxic action on the granulocytes and the toxic dose for some of these stimulants was found to be below their commercially prescribed dose. The long term energetic cost of the use of these stimulants and the concomitant potential for a reduction in growth rate of cultured decapod crustaceans, which is fundamental to the success of commercial aquaculture, is identified and discussed
Changes in immune gene expression and resistance to bacterial infection in lobster (Homarus gammarus) post-larval stage VI following acute or chronic exposure to immune stimulating compound
No full textReal-time PCR was used to measure changes in transcript abundance of genes encoding important immune proteins, namely prophenoloxidase (proPO gene), β-1,3-glucan binding protein (βGBP gene) and a 12.2 kDa antimicrobial peptide (amp gene) in post-larval stage VI (PLVI) juveniles of the European lobster, Homarus gammarus. Gene expression was studied in both healthy PLVI and following single or repeat exposure to a range of compounds claimed to induce immune reactivity. A single acute (3-h) exposure to any of the tested stimulants did not produce a significant increase in expression of either the proPO or βGBP genes, measured 6 h after stimulation. However, there were a small sub-group of positive responders, identified mainly from βGBP expression, within the experimental groups stimulated with either a β-1,3-glucan or an alginate. There was also no significant increase in the expression of any of the three genes tested 24 h after repeated weekly (3-h) exposures to a either the β-1,3-glucan or the alginate over the longer (36-day) period. The results do show that amp is expressed at an extremely high level compared to proPO or βGBP in healthy animals and a significant correlation was found between the expression of proPO and both βGBP and amp, irrespective of whether or not the larvae were stimulated. None of the immune stimulated compounds improved survival of PLVI challenged with the opportunistic pathogen, Listonella anguillarum, or the lobster pathogen, Aerococcus viridans var. homari. Thus, we found no evidence to support recent claims that immunity and disease resistance can be primed or promoted within a given population of crustaceans or that these animals exhibit functional immune memory to some soluble immune elicitors
Real-time PCR quantification of the in vitro effects of crustacean immunostimulants on gene expression in lobster (Homarus gammarus) granular haemocytes.
No full textThis paper presents data from an investigation of the mode of action of five different crustacean immunostimulants presented to European lobster (Homarus gammarus) granulocytes cultured in vitro. The experiments were designed to test whether or not the immunostimulants could cause the short-term upregulation of genes coding for immune proteins without causing the cells to degranulate. Quantitative measurements of mRNA transcript abundance were made using real-time PCR and it was first necessary to isolate the complete gene sequences coding for the proteins prophenoloxidase (proPO), ?-1,3-glucan binding protein (?GBP) and ?-actin ( ?-act) in the lobster. These sequences were used to design TaqMan™ primer and fluorescent probe sets. The presented data indicated that the majority of the tested immunostimulants did not induce the up-regulation of immune-related gene expression in the granulocytes in isolation. Alternative modes of action, including the in vivo up-regulation of gene expression in haemopoetic tissues, are discussed
Immunostimulation in crustaceans: does it really protect against infection?
No full textThere is a growing need to control, prevent or minimise the devastating effects of disease in crustacean culture
without recourse to toxic chemicals or antibiotics. In keeping with approaches to disease control in fish and higher
mammals, interest is developing in compounds that confer protection and/or enhance immune reactivity to likely
pathogens in shellfish (sometimes, erroneously, referred to as ‘shellfish vaccines’). The agents currently under scrutiny
for crustaceans include glucans, lipopolysaccharides and killed bacterial cells. They are thought to act as ‘immunostimulants’
because of their known effects on the crustacean immune system in vitro. A number papers are now
appearing in the literature claiming to demonstrate their positive impact on immunity and disease resistance. This
review article considers the problem of disease and its control in crustacean farming, describing the types of
immunostimulatory compounds claimed to have positive effects and evaluating their merit in enhancing immune
capability in cultured species. Analysis of the validity of the results of many of the published studies raises questions
about the value of these compounds for cost-effective control of infection in aquaculture, especially for long lasting
protection in both adults and juveniles. This review further discusses the potential risks to the wellbeing of the stock
animals from repeated use of these agents and makes the case for rigorous testing of putative stimulants, at the gene,
protein and functional levels, as well as for the need to consider alternative strategies and approaches to disease control
Cloning of a crustin-like, single whey-acidic-domain, antibacterial peptide from the haemocytes of the European lobster, Homarus gammarus, and its response to infection with bacteria.
No full textDegenerate PCR was used to isolate a 221-base pair nucleotide sequence of a new crustin-like antibacterial peptide from the haemocytes of the European lobster, Homarus gammarus. Rapid amplification of cDNA ends was used to extend the sequence to determine the complete open reading frame and untranslated regions. The inferred amino acid sequence of this peptide was found to be similar to crustin-like peptides isolated for several species of shrimp as well as the shore crab, Carcinus maenas. The sequence also contains a single-whey-acidic protein (WAP) domain, similar to novel antibacterial single-whey-acidic domain (SWD) peptides that have been recently described in the tiger shrimp, Penaeus monodon, and the Pacific white shrimp, Litopenaeus vannamei. Real-time PCR was used to analyse the expression of the gene coding for this peptide. The gene is up regulated after inoculation with the Gram-positive lobster pathogen Aerococcus viridans var. homari but down regulated after inoculation with the Gram-negative bacteria Listonella anguillarum. Phylogenetic analysis of this new peptide shows that it is most related to other antimicrobial crustin peptides and that the crustins are only distantly related to the antibacterial SWD peptides recently described
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
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