Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Comparative study of B-glucan induced respiratory burst measured by nitroblue tetrazolium assay and real-time luminol-enhanced chemiluminescence assay in common carp (Cyrpinus carpio L.)
Vera-Jimenez, N.I. ; Pietretti, D. ; Wiegertjes, G.F. ; Nielsen, M.E. - \ 2013
Fish and Shellfish Immunology 34 (2013)5. - ISSN 1050-4648 - p. 1216 - 1222.
head-kidney leukocytes - hydrogen-peroxide production - trout oncorhynchus-mykiss - diluted whole-blood - rainbow-trout - innate immunity - in-vitro - polymorphonuclear leukocytes - aeromonas-hydrophila - parasite infections
The respiratory burst is an important feature of the immune system. The increase in cellular oxygen uptake that marks the initiation of the respiratory burst is followed by the production of reactive oxygen species (ROS) such as superoxide anion and hydrogen peroxide which plays a role in the clearance of pathogens and tissue regeneration processes. Therefore, the respiratory burst and associated ROS constitute important indicators of fish health status. This paper compares two methods for quantitation of ROS produced during the respiratory burst in common carp: the widely used, single-point measurement based on the intracellular reduction of nitroblue tetrazolium (NBT) and a real-time luminol-enhanced assay based on the detection of native chemiluminescence. Both assays allowed for detection of dose-dependent changes in magnitude of the respiratory burst response induced by ß-glucans in head kidney cells of carp. However, whereas the NBT assay was shown to detect the production of only superoxide anions, the real-time luminol-enhanced assay could detect the production of both superoxide anions and hydrogen peroxide. Only the chemiluminescence assay could reliably record the production of ROS on a real-time scale at frequent and continual time intervals for time course experiments, providing more detailed information on the respiratory burst response. The real-time chemiluminescence assay was used to measure respiratory burst activity in macrophage and neutrophilic granulocyte-enriched head kidney cell fractions and total head kidney cell suspensions and proved to be a fast, reliable, automated multiwell microplate assay to quantitate fish health status modulated by ß-glucans.
Protoanemonin: a natural quorum sensing inhibitor that selectively activates iron starvation response
Fazzini, R.A. ; Skindersoe, M. ; Bielecki, M. ; Puchalka, J. ; Givskov, M. ; Martins Dos Santos, V.A.P. - \ 2013
Environmental Microbiology 15 (2013)1. - ISSN 1462-2912 - p. 111 - 120.
pseudomonas-aeruginosa virulence - to-cell communication - polymorphonuclear leukocytes - genes - expression - infection - bacteria - identification - attenuation - pyocyanin
Many Gram-negative bacteria employ cell-to-cell communication mediated by N-acyl homoserine lactones (quorum sensing) to control expression of a wide range of genes including, but not limited to, genes encoding virulence factors. Outside the laboratory, the bacteria live in complex communities where signals may be perceived across species. We here present a newly found natural quorum sensing inhibitor, produced by the pseudomonads Pseudomonas sp. B13 and Pseudomonas reinekei MT1 as a blind end in the biodegradation of organochloride xenobiotics, which inhibits quorum sensing in P. aeruginosa in naturally occurring concentrations. This catabolite, 4-methylenebut-2-en-4-olide, also known as protoanemonin, has been reported to possess antibacterial properties, but seems to have dual functions. Using transcriptomics and proteomics, we found that protoanemonin significantly reduced expression of genes and secretion of proteins known to be under control of quorum sensing in P. aeruginosa. Moreover, we found activation of genes and gene products involved in iron starvation response. It is thus likely that inhibition of quorum sensing, as the production of antibiotics, is a phenomenon found in complex bacterial communities
Chicken heterophils are recruited to the site of Salmonella infection and release antibacterial mature Cathelicidin-2 upon stimulation with LPS
Dijk, A. van; Tersteeg-Zuiderveld, M.H.G. ; Tjeerdsma-van Bokhoven, J.L.M. ; Jansman, A.J.M. ; Veldhuizen, E.J. ; Haagsman, H.P. - \ 2009
Molecular Immunology 46 (2009)7. - ISSN 0161-5890 - p. 1517 - 1526.
antimicrobial peptides - polymorphonuclear leukocytes - neutrophil maturation - microbicidal activity - increasing protein - avian heterophils - gene-expression - innate immunity - granules - inflammation
The biological functions of avian cathelicidins are poorly defined. In mammals, cathelicidins have shown to possess potent broad-range antimicrobial activity as well as immunomodulatory activities. Therefore, we investigated the microbicidal activities and localization of Cathelicidin-2 in non-infected and Salmonella-challenged broiler chickens. Using immunohistochemistry, Cathelicidin-2 was shown to be abundantly present in heterophils, localized in the large rod-shaped granules, but absent in other peripheral blood cells and intestinal epithelial cells. Cathelicidin-2 synthesis was observed to be initiated at the early promyelocyte stage. Considerable infiltration of Cathelicidin-2 containing heterophils was observed in the jejunum of Salmonella enteritidis-challenged broilers within 8 h post-infection. Heterophils were shown to release mature Cathelicidin-2 peptide upon stimulation with Salmonella-derived LPS in a time-dependent way. Processing of the Cathelicidin-2 precursor was mediated by serine proteases with a divalent cation dependency. Cathelicidin-2 peptide showed potent bactericidal and fungicidal activity against all tested microorganisms, including chicken-specific Salmonella isolates. These results underscore the importance of avian heterophils as a first line of defence against invading pathogens and implicate that via heterophil-mediated release, cathelicidins may greatly contribute to avian innate immunity
Kinetics of local and systemic isoforms of serum amyloid A in bovine mastitic milk
Jacobsen, S. ; Niewold, T.A. ; Kornalijnslijper, E. ; Toussaint, M.J.M. ; Gruys, E. - \ 2005
Veterinary Immunology and Immunopathology 104 (2005)1-2. - ISSN 0165-2427 - p. 21 - 31.
acute-phase response - escherichia-coli mastitis - dairy-cows - polymorphonuclear leukocytes - clinical mastitis - saa protein - expression - haptoglobin - infection - cattle
The aim of the present study was to characterise the serum amyloid A (SAA) response to intramammary inoculation of Escherichia coli and to examine the distribution of hepatically and extrahepatically produced SAA isoforms in plasma and milk from cows with mastitis. Milk and plasma SAA concentrations were determined before and after experimental induction of E. coli mastitis in six dairy cows. The milk SAA response was characterised by low or undetectable levels before inoculation, very rapid and large increases in concentration after inoculation, and rapid decline towards baseline levels after resolution of disease. In plasma from cows with experimentally induced E. coli mastitis, four hepatically derived SAA isoforms with apparent isoelectric point (pI) values of 5.8, 6.2, 6.8 and 7.4 were demonstrated by denaturing isoelectric focusing. In milk three highly alkaline isoforms with apparent pI values above 9.3 appeared 12 h post-inoculation. These isoforms were not present in any of the plasma samples, and it therefore seems likely that they were locally produced, tissue-specific isoforms. At 24¿36 h post-inoculation one or more acidic isoforms corresponding to those found in plasma appeared in the milk samples. The isoforms demonstrated in plasma from cows with E. coli mastitis were also present in serum obtained from three cows with clinical Streptococcus uberis mastitis. In conclusion, experimentally induced E. coli mastitis is accompanied by a prominent SAA response. The results of the present study indicate that SAA accumulation in mastitic milk is the result of both local synthesis of SAA and of hepatically derived SAA gaining access to the milk due to increased permeability of the blood¿milk barrier.
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