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- Arnason, T., et al.
(författare)
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Impact of temperature and growth hormone on growth physiology of juvenile Atlantic wolffish (Anarhichas lupus)
- 2019
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Ingår i: Aquaculture. - : Elsevier BV. - 0044-8486. ; 504, s. 404-413
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Tidskriftsartikel (refereegranskat)abstract
- The effects of temperature and growth hormone (GH) implantation on growth of juvenile Atlantic wolffish (Anarhichas lupus) were investigated. The year-long study had three sequential experimental phases (EP) termed EP1, EP2 and EP3, lasting for 6, 9 and 37 weeks, respectively. The experimental fish were divided into four groups and reared at different target temperatures (3, 7, 11 and 15 degrees C) during EP1 and EP2, but at a constant temperature of 7 degrees C during EP3. At the beginning of EP2, half of the fish from each group was implanted with formulation of recombinant bovine GH (Posilac (R)), while the other half was sham-implanted with vehicle. The optimal temperature for growth (T-opt.G) of early juveniles (geometric mean weight 7.5 g) was determined as 12.1 degrees C during EP1, while the upper critical temperature (Tc) was concluded to be very close to 15 degrees C, as fish at that temperature had stunted growth, increased mortality and showed external signs of skeletal deformities. Thus, the species was found to be relatively stenothermic during the early juvenile stages and therefore vulnerable to relatively modest increases in environmental temperature above T-opt.G At 15 degrees C, GH implantation had no effects on growth rate. This indicates that the high allostatic load at this temperature leaves no scope for increased growth. In contrast, at lower rearing temperatures, the GH implantation had substantial, long-term effects on growth rate and induced remarkably similar relative growth stimulation at 3, 7 and 11 degrees C, suggesting a temperature-independent mechanism for the growth-promoting effects of GH.
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| 2. |
- Arnason, T., et al.
(författare)
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Long-term rearing of Arctic charr Salvelinus alpinus under different salinity regimes at constant temperature
- 2014
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Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112. ; 85:4, s. 1145-1162
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Tidskriftsartikel (refereegranskat)abstract
- Arctic charr Salvelinus alpinus of the Holar strain (mean+/- s. e. body mass= 152.1+/-3.1g) were reared at four different salinity regimes at a constant temperature of 7.4 degrees C. Two groups were given a three-month acclimation in salinity 18 before the salinity was increased to either 25 or 29 (groups called A25 and A29), and two groups were reared in salinities 25 or 29 over the full experimental period of 409 days (groups called F25 and F29). In the first 3months, the A25 and A29 groups had the highest growth rates. By October 2011, there were no significant differences (two-way nested ANOVA, P> 0.05) in the mean body masses among A25, F25 and F29 (c. 1450 g), whereas A29 had a lower mean mass (1282 g). The growth in the last period from October 2011 to January 2012 was reduced by sexual maturation in the highest salinity regimes (A29 and F29), whereas fish in groups A25 and F25 showed high growth throughout the study. Males in all salinity groups had higher growth rates than females for the most part of the study, but the divergence between the sexes was most pronounced in the highest salinity regimes. All salinity groups showed distinct changes in Na+, K+-ATPase activity, with high activity in spring and summer, and lower activity in the autumn. Plasma sodium (Na+) levels were stable indicating that none of the experimental groups had problems in maintaining hydromineral balance during the study. While plasma leptin levels were not affected by salinity regimes, it was noted that these levels were 13-30% higher in fish with empty guts compared with those having food in their gut at the time of sampling. This suggests a link between leptin levels and food intake, indicating that this hormone may play a role in food intake and energy allocation in fishes.
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| 3. |
- Steinarsson, A. O., et al.
(författare)
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Short-term progression of cardiometabolic risk factors in relation to age at type 2 diabetes diagnosis: a longitudinal observational study of 100,606 individuals from the Swedish National Diabetes Register
- 2018
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 0012-186X .- 1432-0428. ; 61:3, s. 599-606
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Tidskriftsartikel (refereegranskat)abstract
- Aims/hypothesis The reasons underlying a greater association of premature mortality with early-onset type 2 diabetes relative to late-onset disease are unclear. We evaluated the clinical characteristics at type 2 diabetes diagnosis and the broad trajectories in cardiometabolic risk factors over the initial years following diagnosis in relation to age at diagnosis. Methods Our cohort consisted of 100,606 individuals with newly diagnosed type 2 diabetes enrolled in the Swedish National Diabetes Register from 2002 to 2012. The average follow-up time was 2.8 years. Analyses were performed using a linear mixed-effects model for continuous risk factors and a mixed generalised linear model with a logistic link function for dichotomous risk factors. Results The individuals diagnosed at the youngest age (18-44 years) were more often male and had the highest BMI (mean of 33.4 kg/m(2)) at diagnosis and during follow-up compared with all other groups (those diagnosed at 45-59 years, 60-74 years and >= 75 years; p < 0.05), being similar to 5 kg/m(2) higher than the oldest group. Although HbA(1c) patterns were similar between all age groups, there was a difference of about 5 mmol/mol (0.45%) between the two groups at 8 years post-diagnosis (p < 0.05). Additionally, individuals diagnosed younger had similar to 0.7 mmol/l higher triacylglycerol, and similar to 0.2 mmol/l lower HDL-cholesterol levels at diagnosis relative to the oldest group. Such differences continued for several years post diagnosis. Yet, although more of these younger individuals were receiving oral glucose-lowering agents, other cardioprotective therapies were prescribed less often in this group. Differences in BMI, blood glucose and lipid levels remained with adjustment for potential confounders, including marital status, education and country of birth, and, where relevant, differential treatments by age, and in those with at least 5 years of follow-up. Conclusions/interpretation Individuals who develop type 2 diabetes at a younger age are more frequently obese, display a more adverse lipid profile, have higher HbA1c and a faster deterioration in glycaemic control compared with individuals who develop diabetes later in life. These differences largely remain for several years after diagnosis and support the notion that early-onset type 2 diabetes may be a more pathogenic condition than late-onset disease.
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| 4. |
- Arnason, T., et al.
(författare)
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Effects of salinity and temperature on growth, plasma ions, cortisol and immune parameters of juvenile Atlantic cod (Gadus morhua)
- 2013
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Ingår i: Aquaculture. - : Elsevier BV. - 0044-8486. ; 380-383, s. 70-79
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Tidskriftsartikel (refereegranskat)abstract
- The effects of salinity and temperature on growth, plasma ions, cortisol and immune parameters were investigated in two experiments. In the first experiment small, medium and large juvenile Atlantic cod Gadus morhua (initial average weights of 1.9, 8 and 83 g, respectively) were reared at four constant salinities (6 to 32 parts per thousand) for a short period (19-57 days, depending on size), then returned to seawater (32 parts per thousand) without acclimation and reared for another period (20-391 days). The highest growth rates were found at 10 parts per thousand in all size-classes. After the fish were returned to seawater the growth rates were inversely related to the salinity change in all size-classes and long-term rearing of the medium-sized fish revealed that abrupt salinity increase from 6 and 10 parts per thousand to seawater may permanently reduce the growth capacity of juvenile cod. In another long-term experiment, there was no significant difference in the growth rate of cod (initial average weight 3.4 g) reared at either 13.5 or 32 parts per thousand for 187 days. Rearing at 13.5 parts per thousand neither enhanced growth rate at 6.3 degrees C nor at 10 degrees C in larger juveniles (>245 g) compared with rearing in seawater. The study shows that rearing salinity and abrupt salinity changes have limited or no effects on stress and immune-related parameters, and there are no indications of ion regulatory disturbances at salinities as low as 6 parts per thousand. This shows that the Atlantic cod is an extremely euryhaline marine teleost species, and indicates that commercial Atlantic cod aquaculture can just as well be carried out in locations with low as with high environmental salinity. (C) 2012 Published by Elsevier B.V.
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