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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    Experimental validation of geosmin uptake in rainbow trout, Oncorhynchus mykiss (Waldbaum) suggests biotransformation
    Schram, Edward ; Schrama, Johan W. ; Kooten, Tobias van; Kwadijk, Christiaan J.A.F. ; Kampen, Harm ; Kampen, Harm ; Heul, Jan W. van de; Verreth, Johan A.J. ; Murk, Albertinka J. - \ 2018
    Aquaculture Research 49 (2018)2. - ISSN 1355-557X - p. 668 - 675.
    bioconcentration - biotransformation - geosmin - off-flavour - rainbow trout - water-lipid partitioning
    The bioconcentration of waterborne geosmin in rainbow trout, Oncorhynchus mykiss (Waldbaum) was assessed. Fifty rainbow trout with a mean (SD) weight of 226.6 (29.0) g and lipid content of 6.2 (0.6) % (w/w) were exposed to geosmin in static water for 0, 2, 4, 6, 8, 12, 24, 36, 48 and 120 hr, with one tank containing five fish for eac h exposure period. Geosmin concentrations were measured in fish tissue and water samples collected over time. With time the geosmin concentration in the fish increased and decreased in the water. However, the total absolute amount of geosmin in the system declined over time which could be explained by induction of biotransformation. This is in accordance with the decreasing lipid normalized geosmin levels in the liver compared with the liver-free carcass. Geosmin distribution within rainbow trout clearly is not exclusively governed by the lipid content of tissues. In vivo geosmin bioconcentration in rainbow trout is slower and the body burden reached is lower than the generally accepted theoretical model predicts.
    Granulomatous enteritis in rainbow trout (Oncorhynchus mykiss) associated with soya bean meal regardless of water dissolved oxygen level
    Mosberian-Tanha, P. ; Landsverk, T. ; Press, C.M. ; Mydland, L.T. ; Schrama, J.W. ; Øverland, M. - \ 2018
    Journal of Fish Diseases 41 (2018)2. - ISSN 0140-7775 - p. 269 - 280.
    foamy macrophages - granulomatous enteritis - hypoxia - rainbow trout - soya bean meal
    This study investigated morphological changes associated with soya bean meal-induced enteritis (SBMIE) in distal intestine (DI) of rainbow trout (Oncorhynchus mykiss) fed a soya bean meal (SBM)-based diet and exposed to normoxia or hypoxia created by optimal and low water flow rates, respectively. A 28-day adaption period was followed by a 42-day challenge period where 600 fish were subjected to dietary challenge and/or hypoxia. Twelve tanks each containing 50 juvenile trout were assigned randomly in triplicate to each treatment. Histopathological and immunohistochemical evaluation revealed pathological features that have not previously been described in association with SBMIE. Vacuolar degeneration of epithelial cells mainly at the base of mucosal folds, epithelial cysts, epithelial dysplasia, necrosis, shedding of necrotic cells, and granulomatous inflammation including infiltration of enlarged, sometimes finely vacuolated or “foamy” macrophages, multinucleated giant cells and increased proliferation of fibroblasts were observed. Acid-fast bacteria were not detected in enlarged macrophages; however, these cells contained AB-PAS- and sometimes cytokeratin-positive material, which was interpreted to be of epithelial/goblet cell origin. Hypoxia did not affect the morphological changes in DI. These results suggest that SBM was associated with a granulomatous form of enteritis in DI of rainbow trout regardless of water oxygen level.
    Bacterial translocation and in vivo assessment of intestinal barrier permeability in Rainbow trout (Oncorhynchus mykiss) with and without soyabean meal-induced inflammation
    Mosberian Tanha, Peyman ; Overland, M. ; Landsverk, Thor ; Reveco, Felipe E. ; Schrama, J.W. ; Roem, A.J. ; Agger, Jane W. ; Midland, Liv T. - \ 2016
    Journal of Nutritional Science 5 (2016). - ISSN 2048-6790 - 10 p.
    rainbow trout - soyabean meal - enteritis - Intestinal permeability - permeability markers
    The primary aim of this experiment was to evaluate the intestinal barrier permeability in vivo in rainbow trout (Oncorhynchus mykiss) fed increasing levels of soyabean meal (SBM). The relationship between SBM-induced enteritis (SBMIE) and the permeability markers was also investigated. Our results showed that the mean score of morphological parameters was significantly higher as a result of 37·5 % SBM inclusion in the diet, while the scores of fish fed 25 % SBM or lower were not different from those of the fish meal-fed controls (P < 0·05). SBMIE was found in the distal intestine (DI) in 18 % of the fish (eleven of sixty): ten in the 37·5 % SBM-fed group and one in the 25 % SBM-fed group. Sugar markers in plasma showed large variation among individuals probably due to variation in feed intake. We found, however, a significant linear increase in the level of plasma d-lactate with increasing SBM inclusion level (P < 0·0001). Plasma concentration of endotoxin was not significantly different in groups with or without SBMIE. Some individual fish showed high values of endotoxin in blood, but the same individuals did not show any bacterial translocation. Plasma bacterial DNA was detected in 28 % of the fish with SBMIE, and 8 % of non-SBMIE fish (P = 0·07). Plasma concentration of d-lactate was significantly higher in fish with SBMIE (P < 0·0001). To conclude, SBMIE in the DI of rainbow trout was associated with an increase in bacterial translocation and plasma d-lactate concentration, suggesting that these permeability markers can be used to evaluate intestinal permeability in vivo.
    Next-generation salmonid alphavirus vaccine development
    Hikke, M.C. - \ 2016
    Wageningen University. Promotor(en): Just Vlak, co-promotor(en): Gorben Pijlman. - Wageningen : Wageningen University - ISBN 9789462577404 - 159
    alphavirus - atlantic salmon - rainbow trout - vaccine development - immunity - virology - fish culture - aquaculture - biotechnology - alfavirus - europese zalm - regenboogforel - vaccinontwikkeling - immuniteit - virologie - visteelt - aquacultuur - biotechnologie


    Aquaculture is essential to meet the current and future demands for seafood to feed the world population. Atlantic salmon and rainbow trout are two of the most cultured aquaculture species. A pathogen that threatens these species is salmonid alphavirus (SAV). A current inactivated virus vaccine against SAV provides cross-protection against all SAV subtypes in salmonids and reduces mortality amongst infected fish. However, protection is not 100% and due to virus growth at low temperature, the vaccine production process is time consuming. In addition, the vaccine needs to be injected into the fish, which is a cumbersome process. The work described in this thesis aimed to increase the general knowledge of SAV and to assess current vaccine technologies, and to use this knowledge in designing next-generation vaccines for salmonid aquaculture.

    An alternative cell line to support SAV proliferation was identified, however, the virus production time could not yet outcompete the current SAV production system. Making use of the baculovirus insect cell expression system, multiple enveloped virus-like particle (eVLP), and core-like particle (CLP) prototype vaccines were produced in insect cells at high temperature. An in vivo vaccination study showed, however, that these vaccines could not readily protect Atlantic salmon against SAV. The low temperature-dependent replication of SAV was attributed to the glycoprotein E2, and it was found that E2 only correctly travelled to the cell surface at low temperature, and in the presence of glycoprotein E1. The biological impact of this finding was confirmed in the development and in vivo testing of a DNA-launched replicon vaccine. The effective DNA-launched replicon vaccine was extended by delivery of the capsid protein in trans. It was hypothesized that viral replicon particles (VRP) were formed in vivo, which would cause an additional single round of infection and might further elevate the immune response in comparison to the replicon vaccine. A second animal trial indicated that the inclusion of capsid did not yet improve vaccine efficacy. This trial however did show that a DNA vaccine transiently expressing the SAV structural proteins provided superior protection over both replicon vaccines (with and without capsid).

    In this thesis, some virus characteristics, such as the cause of temperature-dependency of SAV replication, of an unique aquatic virus were further explored. The production and in vivo testing of multiple next-generation vaccines defined the prerequisites for induction of a potent immune response in Atlantic salmon. A prototype DNA-launched replicon vaccine has shown potential for further development. The research described in this thesis contributes to the development of next-generation vaccines in the challenging area of fish vaccinology.

    Scoping study Turkish Rainbow trout aquaculture
    Schram, E. - \ 2016
    IJmuiden : IMARES (Report / IMARES C005/16) - 19
    rainbow trout - recirculating aquaculture systems - fish culture - industry - stakeholders - companies - feasibility studies - turkey - regenboogforel - recirculatie aquacultuur systemen - visteelt - industrie - stakeholders - kapitaalvennootschappen - haalbaarheidsstudies - turkije
    One size fits all? : optimization of rainbow trout breeding program under diverse preferences and genotype-by-environment interaction
    Sae-Lim, P. - \ 2013
    Wageningen University. Promotor(en): Johan van Arendonk, co-promotor(en): Hans Komen; A. Kause. - S.l. : s.n. - ISBN 9789461734648 - 200
    regenboogforel - dierveredeling - veredelingsprogramma's - genotype-milieu interactie - optimalisatie - kenmerken - genetische winst - selectief fokken - simulatie - visteelt - aquacultuur - rainbow trout - animal breeding - breeding programmes - genotype environment interaction - optimization - traits - genetic gain - selective breeding - simulation - fish culture - aquaculture

    Global fish breeders distribute improved animal material to several continents to be farmed under diverse environments, and for very different market conditions. When establishing a global breeding program, there is a need to assess whether or not a single breeding objective satisfies the markets across different countries. It may be challenging to develop a single fish stock that performs well across all environments due to genotype-by-environment interaction (GxE). GxE is a phenomenon describing the possibility that different genotypes have a different sensitivity to changes in an environment. The objective of this thesis was to develop an optimized global breeding program for rainbow trout (Oncorhynchus mykiss) in terms of a balanced breeding goal that satisfies preferences of trout producers and maximized genetic gains across environments in the presence of GxE in production traits. Analytic hierarchy process (AHP) was used to estimate preferences, which can be aggregated to consensus preference values using weighted goal programming (WGP). The analysis revealed that the 6 most important traits were thermal growth coefficient (TGC), survival (Surv), feed conversion ratio (FCR), condition factor (CF), fillet percentage (FIL%), and late maturation (LMat). Individual trait preferences are different for farmers having different farming environments and producing different end-products. Calculating consensus preference values resulted in consensus desired genetic gains. To satisfy most farmers, consensus desired genetic gains can be taken into account in a global breeding strategy. Strong genotype re-ranking was found for all growth traits across environments. Based on simulation, re-location of breeding program led to highest total genetic gain for body weight at harvest. Alternatively, including sib performance into selection index increased genetic gain in all environments. Finally, environment-specific program can be used, but this is costly. There is a possibility of a conflict between 2 profits: from a breeding company and fish farmers and an optimum solution for that conflict can be found by using macroeconomics and cost-benefit analysis.

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