46 research outputs found
Isolated soya protein with standardised levels of isoflavones, cotyledon soya fibres and soya phospholipids improves plasma lipids in hypercholesterolaemia: a double-blind, placebo-controlled trial of a yoghurt formulation
Shedding Light on Fish Otolith Biomineralization Using a Bioenergetic Approach
Otoliths are biocalcified bodies connected to the sensory system in the inner ears of fish. Their layered, biorhythm-following formation provides individual records of the age, the individual history and the natural environment of extinct and living fish species. Such data are critical for ecosystem and fisheries monitoring. They however often lack validation and the poor understanding of biomineralization mechanisms has led to striking examples of misinterpretations and subsequent erroneous conclusions in fish ecology and fisheries management. Here we develop and validate a numerical model of otolith biomineralization. Based on a general bioenergetic theory, it disentangles the complex interplay between metabolic and temperature effects on biomineralization. This model resolves controversial issues and explains poorly understood observations of otolith formation. It represents a unique simulation tool to improve otolith interpretation and applications, and, beyond, to address the effects of both climate change and ocean acidification on other biomineralizing organisms such as corals and bivalves
Listening In on the Past: What Can Otolith δ18O Values Really Tell Us about the Environmental History of Fishes?
Oxygen isotope ratios from fish otoliths are used to discriminate marine stocks and reconstruct past climate, assuming that variations in otolith δ18O values closely reflect differences in temperature history of fish when accounting for salinity induced variability in water δ18O. To investigate this, we exploited the environmental and migratory data gathered from a decade using archival tags to study the behaviour of adult plaice (Pleuronectes platessa L.) in the North Sea. Based on the tag-derived monthly distributions of the fish and corresponding temperature and salinity estimates modelled across three consecutive years, we first predicted annual otolith δ18O values for three geographically discrete offshore sub-stocks, using three alternative plausible scenarios for otolith growth. Comparison of predicted vs. measured annual δ18O values demonstrated >96% correct prediction of sub-stock membership, irrespective of the otolith growth scenario. Pronounced inter-stock differences in δ18O values, notably in summer, provide a robust marker for reconstructing broad-scale plaice distribution in the North Sea. However, although largely congruent, measured and predicted annual δ18O values of did not fully match. Small, but consistent, offsets were also observed between individual high-resolution otolith δ18O values measured during tag recording time and corresponding δ18O predictions using concomitant tag-recorded temperatures and location-specific salinity estimates. The nature of the shifts differed among sub-stocks, suggesting specific vital effects linked to variation in physiological response to temperature. Therefore, although otolith δ18O in free-ranging fish largely reflects environmental temperature and salinity, we counsel prudence when interpreting otolith δ18O data for stock discrimination or temperature reconstruction until the mechanisms underpinning otolith δ18O signature acquisition, and associated variation, are clarified
Boom and bust of a moose population – a call for integrated forest management
This is the postprint version of the article. The published article can be located at www.springerlink.comThere is increasing pressure to manage forests
for multiple objectives, including ecosystem services and
biodiversity, alongside timber production. However, few
forests are currently co-managed for timber and wildlife,
despite potential economic and conservation benefits. We
present empirical data from a commercial Norway spruce
(
Picea abies
) and Scots pine (
Pinus sylvestris
) production
system in southern Norway in which moose (
Alces alces
)
are an important secondary product. Combining long-term
hunting and forestry records, we identified temporal vari-
ation in clear-felling over the past five decades, peaking in
the 1970s. Herbicide treatment of regenerating stands and a
fivefold increase in moose harvest has lead to a reduction in
availability of successional forest per moose of
[
90 %
since the 1960s. Field estimates showed that spraying with
the herbicide glyphosate reduced forage availability by 60
and 96 % in summer and winter, respectively, 4 years after
treatment. It also reduced moose use and habitat selection
of young spruce stands compared with unsprayed stands.
Together these lines of evidence suggest that forest man-
agement led to an increase in moose carrying capacity
during the 1970s and a subsequent decline thereafter. This
is likely to have contributed to observed reductions in moose population productivity in southern Norway and is
counter to sustainable resource management. We therefore
call for better integration and long-term planning between
forestry and wildlife management to minimise forest
damage and the development of large fluctuations in
ungulate populations
Separation of Norwegian coastal cod and Northeast Arctic cod by otolith morphometry
For stock assessment purposes, Atlantic cod (Gadus morhua) from the coastal and offshore regions off
northern Norway is usually allocated to Norwegian coastal cod (NCC) and Northeast Arctic cod (NEAC)
by internal morphological features of their otoliths. As this classification is subject to individual
interpretation, this study investigated an alternative objective approach for the separation of the two cod
groups, using otolith shape analysis. Otolith samples from coastal areas along northern Norway and from
the Barents Sea were analysed by univariate shape descriptors and Elliptical Fourier Analysis (EFA).
When combining those methods, the classification score was 89% for NCC and 90% for NEAC. When
genetic typing data (Pan I marker) were used as reference, the classification scores were reduced to 83%
for NCC and 76% for NEAC. These results imply that differences in internal otolith morphology are
translated to a large extent into the outer shape, but that those cannot directly be linked to genetic
structure. Environmental conditions, however, seem to have a considerable influence on how otolith
growth increments and consequently otolith shapes are formed. As the various fjord systems in Norway
provide local habitats and as differences within the NCC with regard to genetic structure and life-history
parameters had been found in earlier studies, variation of NCC otolith shapes between three coastal
regions was also examined. The region classification scores for reader-typed NCC varied between 60%
and 81%. Apart from the outer shape analyses, experimental work on the detection of internal (annuli)
shapes was carried out and will be presented as work in progress.
Keywords: Stock identification; Otolith shape analysis; Northeast Atlantic; Norway; Atlantic cod; Gadus
morhu
Effects of micromilling on delta O-18 in biogenic aragonite
Extraction of small aliquots ( mu g- mg) from aragonite samples such as corals, sclerosponges, bivalves, and otoliths is required for bulk oxygen isotope analyses. However, aragonite is a metastable polymorph of calcium carbonate that undergoes transformation to calcite, which is the more thermodynamically stable polymorph of CaCO3. This polymorph transformation occurs via heating and/ or stress, and such conditions may occur during drilling. During this polymorph transition, exchange with atmospheric or organic C and O is possible. Therefore extracting aliquots during drilling without modification or contamination via isotope exchange is imperative for accurate isotopic analysis. Using a micromill, aliquots were taken from aragonite cod otoliths that had been grown in the laboratory under stable temperature conditions. X- ray diffraction analysis showed that although 6% of the sample converts to calcite during drilling, there is no significant effect on delta O-18.</p
An in vitro study on the genotoxic effect of substituted furans in cells transfected with human metabolizing enzymes: 2,5-dimethylfuran and furfuryl alcohol
2,5-Dimethylfuran (DMF) and furfuryl alcohol (FFA) are two substituted furans that are formed during the processing of foods and have also been used as food flavorings. DMF and FFA are proposed to be bioactivated by human sulfotransferases (SULTs) which are not expressed in conventional cell lines used for genotoxicity testing. Therefore, in addition to the standard V79 cell line, we used a transfected V79 derived cell line co-expressing human cytochrome P450 (CYP) 2E1 and human SULT1A1 to assess the genotoxicity of DMF and FFA. The alkaline single cell gel electrophoresis (SCGE) assay was used to detect DNA damage in the form of single strand breaks and alkali-labile sites after exposure to DMF (0.5h; 0.5, 1, 1.5 or 2mM) or FFA (3h; 1, 3, 6 or 15mM). DMF induced DNA damage in V79 cells in a concentration-dependent manner irrespective of the expression of human CYP2E1 and SULT1A1. Almost no increase in the level of DNA damage was detected after exposure to FFA, except for a weak effect at the highest concentration in the transfected cell line. The results suggest that DNA damage in V79 cells from exposure to DMF detected by the alkaline SCGE assay is independent of human CYP2E1 and SULT1A1, and the genotoxic effect of FFA, as assessed by SCGE, is minimal in V79 cells
On the edge of death: Rates of decline and lower thresholds of biochemical condition in food-deprived fish larvae and juveniles
Gaining reliable estimates of how long fish early life stages can survive without feeding and how starvation rate
and time until death are influenced by body size, temperature and species is critical to understanding processes
controlling mortality in the sea. The present study is an across-species analysis of starvation-induced changes in
biochemical condition in early life stages of ninemarine and freshwater fishes. Datawere compiled on changes in
body size (dry weight, DW) and biochemical condition (standardized RNA–DNA ratio, sRD) throughout the
course of starvation of yolk-sac and feeding larvae and juveniles in the laboratory. In all cases, themean biochemical
condition of groups decreased exponentially with starvation time, regardless of initial condition and endogenous
yolk reserves. A starvation rate for individuals was estimated from discrete 75th percentiles of sampled
populations versus time (degree-days, Dd). The 10th percentile of sRD successfully approximated the lowest,
life-stage-specific biochemical condition (the edge of death). Temperature could explain 59% of the variability
in time to death whereas DW had no effect. Species and life-stage-specific differences in starvation parameters
suggest selective adaptation to food deprivation. Previously published, interspecific functions predicting the relationship
between growth rate and sRD in feeding fish larvae do not apply to individuals experiencing prolonged
food deprivation. Starvation rate, edge of death, and time to death are viable proxies for the physiological processes
under food deprivation of individual fish pre-recruits in the laboratory and provide useful metrics for research
on the role of starvation in the sea