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Waagbo R.,National Institute of Nutrition And Seafood Research
Aquaculture Research | Year: 2010

Studies on vitamin requirement at early stages are difficult and vary in quality, both due to the scientific approach and vitamin analysis. Focus has been on water-soluble vitamins that cause dramatic losses of the offspring in practical farming situations or in wild life, like vitamin C and thiamine deficiencies respectively. Practical solutions including vitamin administration through brood stock and larvae diets have confirmed and corrected the vitamin deficiencies. For the other water-soluble vitamins, the situation is not so obvious. Descriptive studies of folate and vitamin B6 during fish ontogeny have shown a net loss of vitamin during endogenous feeding and a steady transfer of vitamin from the yolk sac into the body compartment, and finally, dramatic increases in body vitamin levels after the start of feeding. The kinetics of mass transfer with ontogeny appears, however, to differ between vitamins. Start of feeding of fish larvae with live or formulated feeds includes several challenges with respect to water-soluble vitamins, including aspects of live feed enrichment and stability, micro-diet leaching, variable feed intakes, immature gastrointestinal tract, variable bioavailability of vitamins and larvae vitamin storage capacity. Consequently, the exact minimum requirements are difficult to estimate and vitamin recommendations need to consider such conditions. © 2009 The Authors. Journal Compilation © 2009 Blackwell Publishing Ltd.

Levsen A.,National Institute of Nutrition And Seafood Research | Karl H.,Max Rubner Institute
Food Control | Year: 2014

Previous studies have shown that Grey gurnard from the North Sea is comparatively heavily infected with the larvae of the parasitic and potentially consumer hazardous nematode Anisakis simplex (s.l.). Especially the high abundance of Anisakis larvae in the fish flesh is of concern regarding the possible intensified utilisation of Grey Gurnard as a food resource. To gain better knowledge of the nematode burden with emphasis on abundance and distribution in the fish flesh, various Grey gurnards from 6 localities across the North Sea, each representing either western, northern or eastern fishing grounds, were examined for anisakid nematodes during summer of 2010 and 2012. The overall prevalence of A.simplex (s.l.) larvae in the gurnards from all localities (n=188) was nearly total, i.e. only a single fish from the northernmost locality (Viking Bank) was apparently not infected. GLM-analyses revealed that catching locality had by far the strongest effect on larval infection probability, both in total (flesh+viscera) and in the fish flesh, while body size (weight) was a weak but still significant predictor of overall A.simplex (s.l.) abundance, but not in the flesh. Thus, the overall larval abundance in the gurnards from the two western localities off the east-coast of British mainland was significantly higher compared to the other catching localities. In the former localities, the overall mean abundance of A.simplex (s.l.) larvae was 35.0±23.9 and 92.2±87.4, and ranged from 14 to 114 and 9 to 397, respectively. It was further shown that 93.8% of the larvae infecting the fish flesh were situated in the belly flaps, i.e. the ventral portion of each flesh side or fillet, independent of catching locality and fish size. However, trimming of the fillets by removing the belly flaps may reduce the abundance in the fillets to, on an average, 0.3 larvae. 2013 Elsevier Ltd.

Hamre K.,National Institute of Nutrition And Seafood Research
Aquaculture Nutrition | Year: 2011

Vitamin E is a generic term for a group of lipid-soluble molecules, the tocopherols and tocotrienols, which have a function in the protection of organisms against lipid oxidation and which also may have other, more specific biological functions. In fish, as in other vertebrates, α-tocopherol (TOH) is preferentially retained in the body compared to the other tocopherols, probably because of the presence of a tocopherol transfer protein (TTP) in the liver which binds the tocopherols with different affinities and returns them to the circulation. Tocopherols that bind weakly to TTP are to a greater extent excreted in the bile. α-TOH interacts with other nutrients, and the requirement therefore varies with the dietary composition. High levels of polyunsaturated fatty acids, and low levels of vitamin C, selenium and astaxanthin increase the requirement. This is attributed to the dynamic nature of both lipid oxidation and the antioxidant defence, where oxidized vitamin E is recycled by other antioxidants. The interactions also determine the display of vitamin E deficiency signs, immune responses and effects on flesh quality. Within the mammalian nutrition research community, there is a controversy as to whether vitamin E is primarily an antioxidant or a specific modulator of cell signalling through regulation of enzyme activities and gene expression and some of the hypotheses are presented in this review. © 2010 Blackwell Publishing Ltd.

Primary head kidney leukocytes from Atlantic cod were isolated to evaluate the use of arachidonic acid and eicosapentaenoic acid by cyclooxygenases and the production of prostaglandins E2 and E3. The expression of cyclooxygenase genes and selected interleukin genes like Interleukin 1β, Interleukin 6, interleukin 8 and interleukin 10 were monitored. Increasing concentrations of eicosapentaenoic acid and arachidonic acid in equal amounts increased cyclooxygenase2 transcription as well as cell secretion of prostaglandin E2. Even though the ratio of the two fatty acids was 1:1, the ratio between prostaglandin E2 and E3 was 50:1. The addition of arachidonic acid alone increased prostaglandin E2 secretion but did not induce cyclooxygenase2 transcription. However, when the concentration of eicosapentaenoic acid was increased, maintaining arachidonic acid constant, both prostaglandin E3 and prostaglandin E2 production was induced and the prostaglandin E2 production was higher than in cell cultures only added arachidonic acid. An up-regulation of cyclooxygenase2 transcription was also observed. The addition of the two fatty acids also affected the immune response by alteration of leukocytic cytokines gene expression. According to our results the Cyclooxygenase in cod seem to prefer arachidonic acid as substrate. Therefore, we suggest that the shift from marine oils (rich in n-3 fatty acids) to plant oils (higher in n-6 fatty acids) in the diet of commercially reared Atlantic cod could have negative effects on the whole organism through the increase in the production of prostaglandins belonging to those derived from n-6 fatty acids. Copyright © 2012 Elsevier Ltd. All rights reserved.

Svanevik C.S.,National Institute of Nutrition And Seafood Research | Lunestad B.T.,National Institute of Nutrition And Seafood Research
International Journal of Food Microbiology | Year: 2011

In this study the microbiota of Atlantic mackerel (Scomber scombrus) collected by a commercial purse seiner was examined. Fish were collected directly from the purse seine and from the Refrigerated Sea Water (RSW) transport tank after loading. The culturable microbiota and Specific Spoilage Bacteria (SSB) were quantified on Iron Agar Lyngby (IAL) and identified using commercially available Biochemical API® kits on pure cultured isolates. These kits showed to be sub-optimal in characterising the isolates, since only half of the strains were identified. The same isolates were also identified by a nucleic acid based PCR-DGGE approach, and only half of the sequences gave the same results as the API®. Characterisation by PCR-DGGE was also performed on bacterial DNA from IAL plates (bulk cell samples) and on samples where the bacterial DNA was extracted directly from fish material without any cultivation (direct DNA samples). The microbiota of Atlantic mackerel was dominated by members of the Gram-negative genera as Psychrobacter sp., Proteus sp., Photobacterium sp., Vibrio sp., Shewanella sp., Synechococcus sp., Oceanisphaerae sp., Bizonia sp., Pseudoalteromonas sp., and members of Flavobacteriaceae. Gram-positive bacteria in the genera Vagococcus sp., Bacillus sp., Mycobacterium sp., Staphylococcus sp., Mycoplasma sp. and Clostridia sp. were also found. Examination by PCR-DGGE and sequencing of the bulk cell pellet after cultivation on IAL, gave a higher number of taxa as compared to extraction and examination of bacterial DNA from fish materials without prior cultivation. This shows the benefit of combining both culture dependent and culture independent methods, when studying the microbiota of marine fish. Several Vibrio spp. were found only in gut samples collected from the purse seine, but in all samples including the skin and the gills collected from the RSW tank, indicating microbial contamination by faecal bacteria from the fish under these transport conditions. © 2011 Elsevier B.V.

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