Tromsø, Norway
Tromsø, Norway

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Bondevik S.,Sogn og Fjordane University College | Bondevik S.,University of Tromsø | Stormo S.K.,Nofima Marin | Skjerdal G.,Sogndal Upper Secondary School
Quaternary Science Reviews | Year: 2012

Chlorophyll in dead plants ordinarily decomposes completely before permanent burial through exposure to light, water and oxygen. Here we describe 8000-year-old terrestrial mosses that retain several percent of its original chlorophyll. The mosses were ripped of the land surface, carried 50-100 m off the Norwegian coast of the time, and deposited in depressions on the sea floor by the Storegga tsunami. A little of the chlorophyll survived because, within hours after entraining it, the tsunami buried the mosses in shell-rich sediments. These sediments preserved the chlorophyll by keeping out light and oxygen, and by keeping the pH above 7-three factors known to favour chlorophyll's stability. Because the green mosses were buried alive, their radiocarbon clock started ticking within hours after the Storegga Slide had set off the tsunami. Radiocarbon measurement of the mosses therefore give slide ages of uncommon geological precision, and these, together with a sequence of ages above and below the boundary, date the Storegga Slide to the chilliest decades of the 8.2 ka cold event at 8120-8175 years before AD 1950. North Atlantic coastal- and fjord- climatic records claimed to show evidence of the 8.2 cold event should be carefully examined for possible contamination and disturbance from the Storegga tsunami. © 2012 Elsevier Ltd.

Mikkelsen H.,Nofima Marin | Lund V.,Nofima Marin | Larsen R.,University of Tromsø | Seppola M.,Nofima Marin
Fish and Shellfish Immunology | Year: 2011

The purpose of this study was to investigate the efficacy of three monovalent and a trivalent vibriosis dip vaccines in juvenile Atlantic cod (Gadus morhua L.), examine whether the responses were specific and study the expression of selected immune genes after dip vaccination. In addition, the study addressed whether the deviating isolates of Vibrio anguillarum serotype O2 belongs to another sero-subgroup than the previously established sero-subgroups O2a, O2b and O2c. Rabbit V. anguillarum serotype O2 antiserum adsorbed with V. anguillarum O2a O-antigen was shown, by both ELISA and immunoblotting, to still contain serotype O2 specific antibodies. Cod V. anguillarum serotype O2 antiserum reacted only with isolate of homologous serotype and not with heterologous sero-subgroups. This indicates that the deviating V. anguillarum O2 isolates represent a new sero-subgroup differing from sero-subgroup O2a.The monovalent vaccines included formalin inactivated cultures of V. anguillarum sero-subgroup O2a, O2b or serotype O2, while the trivalent vaccine contained all three sero-subgroups. Cod mounted high protection 7 weeks post dip vaccination with monovalent vaccines when challenged with homologous isolates and significantly lower when challenged with heterologous isolates, regardless of sero-subgroups. The trivalent vaccine resulted in efficient protection against all sero-subgroups tested. Dip vaccination of cod juveniles did not result in detectable antibody production or alteration in gene expression of the heavy chain of IgM and IgD. In the trivalent vaccine group expression of IFNγ and IL-12p40 were significantly up-regulated 3 days post vaccination. However, in groups vaccinated against V. anguillarum sero-subgroups O2b or O2, IL-12p40 and IFNγ gene expression were slightly increased 3 and 55 days post vaccination, respectively. © 2010 Elsevier Ltd.

Sivertsen A.H.,Nofima Marin | Kimiya T.,Japan National Research Institute of Fisheries Science | Heia K.,Nofima Marin
Journal of Food Engineering | Year: 2011

VIS/NIR spectroscopy for differentiating between fresh and frozen-thawed cod fillets and for assessing the freshness as days on ice has been evaluated. Both a handheld interactance probe for doing quick measurements of single fillets and an imaging spectrometer for doing online analysis at industrial speed of one fillet per second, have been used. Results show that frozen-thawed cod fillets can be fully separated from fresh fillets using a small subset of wavelengths in the visible region. Freshness as days on ice can be determined with an accuracy of 1.6 days on individual fillets. The results indicate that oxidation of hemoglobin and myoglobin during freezing-thawing and cold storage on ice are explaining most of the variations seen in the visible region of the spectrum. © 2010 Elsevier Ltd. All rights reserved.

Gjerde B.,Nofima Marin | Odegard J.,Nofima Marin | Thorland I.,Akvaforsk
Aquaculture | Year: 2011

The magnitude of the genetic variation in the susceptibility of Atlantic salmon to Lepeophtheirus salmonis was estimated through a controlled infestation test of 2206 individually tagged post-smolts of 154 full-sib families, i.e. the offspring of 78 sires and 154 dams. The infestation test took place in two replicated tanks with seawater. On average 74 and 36 copepodids per fish were added to tanks 1 and 2, respectively. The number of sessile lice (chalimus II-II stage) per fish (LC) was counted ten days after infestation at which the average body weight of the fish was 260g in each of the two tanks. The average LC per fish was 27.1 (SD=16.4) and 13.9 (SD=13.2) in tanks 1 and 2, respectively while the lice density per fish, calculated as LD=LC/Body weight2/3, was 0.66 (SD=0.38) and 0.34 (SD=0.29). Observed LC was found to increase with increasing body weight, while LD was seemingly independent of body weight. These relationships explain the lower heritability for LD (0.26±0.05) than for LC (0.33±0.05), and a genetic correlation between LC and LD (rg=0.89±0.03) different from unity. The magnitude of the heritability estimate for LD together with the large phenotypic variation of the trait, and a genetic correlation close to unity between LD in the two replicated tanks, shows that there is substantial additive genetic variation in resistance to L. salmonis in Atlantic salmon, and thus a great potential for increasing the resistance through selective breeding. The genetic correlation between LD and harvest body weight recorded on two subsamples of sibs of the lice infected fish reared at two farms was close to and not significantly different from zero (0.06±0.12 and -0.13±0.11). Hence, the increasing lice problem in the salmon industry during the last years is most likely caused by other factors than the selection that has been practised for increased growth rate over the last 3-4 decades. © 2011.

Johnsen H.,Nofima Marin | Andersen O.,Nofima Marin | Andersen O.,Norwegian University of Life Sciences
Gene | Year: 2012

The Doublesex and Mab-3 related transcription factors (Dmrt) are characterised by the zinc finger-like DM domain binding similar DNA sequences, but show different spatio-temporal expression patterns and functions throughout ontogenesis. Dmrt1 is the master regulator of sex determination in very distant metazoans, while Dmrt2 and Dmrt4 are of crucial importance in vertebrate somitogenesis and neurogenesis, respectively. To elucidate the evolutionary divergence of the fish dmrt genes, we examined the expression patterns and the chromosomal synteny of the five dmrt genes identified in the Atlantic cod genome. Quantitative PCR analyses of cod dmrt1, dmrt2a, dmrt3, dmrt4 and dmrt5 revealed distinct expression patterns in the embryo and larvae, and indicated conserved extragonadal functions during early development. Several dmrt genes seem to be involved in the sexual differentiation of gonads and brain, but the sex-dimorphic expression patterns differed substantially between teleosts, suggesting functional switch between Dmrt members. The dmrt2a-dmrt3-dmrt1 cluster was found to be located in a conserved syntenic region, and the flanking genes have become duplicated in teleosts and are closely linked in a paralogous region lacking the dmrt cluster. Similarly, the region containing the fish-specific dmrt2b gene was found to have a paralogous region without a dmrt2b duplicate in a separate linkage group in the teleost genomes. We propose that the teleost segments paralogous to the dmrt2a- and dmrt2b regions, respectively, were formed through the fish-specific whole genome duplication (3R), while dmrt2a and dmrt2b originated from the second round (2R) of whole genome duplication of the ancestral dmrt2. The dmrt2b paralog seems to have been lost in Atlantic cod as in tetrapods and may be a pseudogene in pufferfish, while dmrt2a and dmrt2b have acquired different functions in zebrafish. Contrasting with the retained duplicates of dmrt flanking genes, the massive losses of dmrt duplicates in the vertebrate tetraploidizations suggest that their functions are exquisitely sensitive to gene dosage. © 2012 Elsevier B.V.

This experiment examined and compared the effects of a highly purified immune modulating β-1,3/1,6-glucan product (BG) and of a putative receptor blocking, mannan oligosaccharide rich product (MOS) in Atlantic salmon fed extruded diets containing extracted soybean meal (SBM) or a combination of SBM and extracted sunflower meal (SFM). The BG and MOS products were derived from the cell walls of baker's yeast. A control diet was based on LT-fish meal (FM) and contained no plant protein. Two basic experimental diets were formulated with 32% SBM (FM+S) or with 14% SBM+14% SFM (FM+SS). Following extrusion, four FM+S batches were supplemented with 500 or 1000mg BG or 1000 or 2000mgMOSkg-1, while two FM+SS batches were supplemented with 1000mg BG or 2000mgMOSkg-1. Each diet was fed to three groups of 150 salmon kept in sea pens, and effects on feed intake, growth, nutrient utilisation, gut health, sea lice infestation, and overall performance of the fish were recorded over a period of 70days. The initial weight of the fish was 0.68kg, and the different feed groups grew to final weights ranging from 1.33 to 1.72kg. Compared to the control group, fish fed the diet with 32% SBM ate 18% less, grew 30% slower, had 24% poorer feed efficiency ratio (FER), and also suffered from serious SBM-induced enteritis, diarrhoea, and reduced capacity to digest lipid. Adding BG or MOS to this diet had no detectable effects. Fish fed the diet with 14% SBM+14% SFM ate as much as the control group, but still grew 5% slower, had 7% poorer FER, and suffered from a diarrhoea-like condition and moderate enteritis. Noteworthy, 27% fewer of these fish were infested with salmon lice when compared to the other groups. Adding BG to this diet further reduced the number of lice-infested fish by 28%. Adding MOS to this diet did not affect appetite or lice infestation, but resulted 10% better FER, 8% faster growth (similar to the control group), 11% higher protein retention, less diarrhoea, and most noteworthy: elimination of the SBM-induced enteritis. This clearly demonstrates that gut health is an important production parameter for Atlantic salmon. © 2010 Elsevier B.V.

Gjedrem T.,Nofima Marin
Reviews in Aquaculture | Year: 2010

Individual selection for growth rate has been practised for aquatic species for many years. However, the use of a small number of breeders without records of parentage frequently results in inbreeding depression. AKVAFORSK began the first ever family-based breeding program in aquaculture in 1975 for Atlantic salmon in Norway. The first steps of the program involved estimating the phenotypic and genetic parameters of economically important traits and generating a base population by crossing wild salmon strains. As information on quantitative genetics for salmon was not available, the breeding program started by selecting for body weight. As information was gathered, other traits such as age at sexual maturation, disease resistance and product quality were added to the selection index. The salmon industry was invited to participate in the breeding program, which has been managed by Aqua Gen AS since 1993. The genetic gain achieved has been estimated at approximately 14% per generation with a global benefit/cost ratio estimated at 15/1. © 2010 Blackwell Publishing Asia Pty Ltd.

In aquaculture breeding, resistance against infectious diseases is commonly assessed as time until death under exposure to a pathogen. For some diseases, a fraction of the individuals may appear as "cured" (non-susceptible), and the resulting survival time may thus be a result of two confounded underlying traits, i.e., endurance (individual hazard) and susceptibility (whether at risk or not), which may be accounted for by fitting a cure survival model. We applied a cure model to survival data of Pacific white shrimp (Penaeus vannamei) challenged with the Taura syndrome virus, which is one of the major pathogens of Panaeid shrimp species. In total, 15,261 individuals of 513 full-sib families from three generations were challenge-tested in 21 separate tests (tanks). All challenge-tests were run until mortality naturally ceased. Time-until-event data were analyzed with a mixed cure survival model using Gibbs sampling, treating susceptibility and endurance as separate genetic traits. Overall mortality at the end of test was 28%, while 38% of the population was considered susceptible to the disease. The estimated underlying heritability was high for susceptibility (0.41 ± 0.07), but low for endurance (0.07 ± 0.03). Furthermore, endurance and susceptibility were distinct genetic traits (rg = 0.22 ± 0.25). Estimated breeding values for endurance and susceptibility were only moderately correlated (0.50), while estimated breeding values from classical models for analysis of challenge-test survival (ignoring the cured fraction) were closely correlated with estimated breeding values for susceptibility, but less correlated with estimated breeding values for endurance. For Taura syndrome resistance, endurance and susceptibility are apparently distinct genetic traits. However, genetic evaluation of susceptibility based on the cure model showed clear associations with standard genetic evaluations that ignore the cure fraction for these data. Using the current testing design, genetic variation in observed survival time and absolute survival at the end of test were most likely dominated by genetic variation in susceptibility. If the aim is to reduce susceptibility, earlier termination of the challenge-test or back-truncation of the follow-up period should be avoided, as this may shift focus of selection towards endurance rather than susceptibility. © 2011 Ødegård et al; licensee BioMed Central Ltd.

Odegard J.,Nofima Marin | Sommer A.-I.,Nofima Marin | Praebel A.K.,Nofima Marin
Aquaculture | Year: 2010

Nodavirus are the causative agents of viral nervous necrosis (VNN), and has been shown to cause mortality in numerous fish species worldwide, among them is the Atlantic cod (Gadus morhua L.). In this study, heritability of VNN resistance in Atlantic cod was estimated through challenge testing of 50 large full sib families (∼ 94 fish per family) comprising two genetically distinct groups of Atlantic cod (Norwegian coastal cod and northeast Arctic cod) and their F1 crossbreds. The overall survival (dead/alive) at end of test was 30%, but coastal cod had considerably higher survival (56%) than northeast Arctic cod (10%), while the F1 cross was intermediate (31%). Furthermore, enormous variation in family survival was observed within each group (17 to 82% for coastal cod, 0 to 42% for northeast Arctic cod and 0 to 92% for the F1 cross). As a consequence, the estimated within-strain heritability of survival under challenge testing was extremely high (0.75 ± 0.11 on the underlying scale and 0.43 ± 0.07 on the observable scale). Common environmental effects of full-sib families were not significant in addition to additive genetic effects, but the data structure was not optimal for distinguishing these effects. © 2010 Elsevier B.V. All rights reserved.

Odegard J.,Nofima Marin
Genetics, selection, evolution : GSE | Year: 2010

BACKGROUND: In the genetic analysis of binary traits with one observation per animal, animal threshold models frequently give biased heritability estimates. In some cases, this problem can be circumvented by fitting sire- or sire-dam models. However, these models are not appropriate in cases where individual records exist on parents. Therefore, the aim of our study was to develop a new Gibbs sampling algorithm for a proper estimation of genetic (co)variance components within an animal threshold model framework. METHODS: In the proposed algorithm, individuals are classified as either "informative" or "non-informative" with respect to genetic (co)variance components. The "non-informative" individuals are characterized by their Mendelian sampling deviations (deviance from the mid-parent mean) being completely confounded with a single residual on the underlying liability scale. For threshold models, residual variance on the underlying scale is not identifiable. Hence, variance of fully confounded Mendelian sampling deviations cannot be identified either, but can be inferred from the between-family variation. In the new algorithm, breeding values are sampled as in a standard animal model using the full relationship matrix, but genetic (co)variance components are inferred from the sampled breeding values and relationships between "informative" individuals (usually parents) only. The latter is analogous to a sire-dam model (in cases with no individual records on the parents). RESULTS: When applied to simulated data sets, the standard animal threshold model failed to produce useful results since samples of genetic variance always drifted towards infinity, while the new algorithm produced proper parameter estimates essentially identical to the results from a sire-dam model (given the fact that no individual records exist for the parents). Furthermore, the new algorithm showed much faster Markov chain mixing properties for genetic parameters (similar to the sire-dam model). CONCLUSIONS: The new algorithm to estimate genetic parameters via Gibbs sampling solves the bias problems typically occurring in animal threshold model analysis of binary traits with one observation per animal. Furthermore, the method considerably speeds up mixing properties of the Gibbs sampler with respect to genetic parameters, which would be an advantage of any linear or non-linear animal model.

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