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- Neregård, Lena, 1973, et al.
(författare)
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Growth hormone affects behaviour of wild brown trout Salmo trutta in territorial owner–intruder conflicts
- 2008
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Ingår i: Journal of Fish Biology. - : Wiley. - 1095-8649 .- 0022-1112. ; 73:10, s. 2341-2351
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Tidskriftsartikel (refereegranskat)abstract
- The effects of growth hormone (GH) implants on aggression, and ability to win dyadic territorial conflicts were studied in brown trout Salmo trutta parr. Bovine GH or vehicle (C) was given to either the territory owner or the intruder in four treatment combinations: C and C, C and GH, GH and C, GH and GH (owner and intruder). GH-treated intruders initiated significantly more conflicts compared to control intruders. Furthermore, GH treatment of either the owner or intruder tended to increase aggression of the intruder. This indicates that intruders have more scope for motivational increase, while the motivation of owners is already at a maximum. The GH treatment, however, did not affect the outcome of the conflict. It thus appears that growth enhancement increases intruder aggression without increasing the chance of winning the conflict, which may have implications for the effect of growth-selected or growth-enhanced farmed Atlantic salmon Salmo salar on wild populations.
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- Neregård, Lena, 1973, et al.
(författare)
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Wild Atlantic salmon Salmo salar L. strains have greater growth potential than a domesticated strain selected for fast growth
- 2008
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Ingår i: Journal of Fish Biology. - : Wiley. - 1095-8649 .- 0022-1112. ; 73:1, s. 79-95
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Tidskriftsartikel (refereegranskat)abstract
- A study was undertaken to examine the responses of three Atlantic salmon Salmo salar strains to growth hormone (GH) treatment. A positive growth response to sustained-release GH implants was found in two wild strains (Namsen and Imsa) as well as one domesticated strain (AquaGen). The data revealed that the growth-selected AquaGen strain has further growth potential, however, a stronger growth response was observed in the wild strains which outgrew the domesticated strain after GH treatment. These observations suggest that some growth potential may have been lost during the selection for rapid growth in the AquaGen strain. In September, the parr were GH implanted and in December sampled for plasma GH and insulin-like growth factor I (IGF-I) levels, liver, muscle and gill GH receptor, IGF-I mRNA levels, gill Na+,K+-ATPase activity, muscle and liver lipid content and body silvering. Low temperature and seasonal growth cessation probably explains the relatively limited GH effects found. Body silvering in all strains was positively correlated to size. GH increased IGF-I plasma levels in the Namsen strain inspite of liver IGF-I mRNA levels being lower in GH-treated fish.
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- Raven, P. A., et al.
(författare)
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Growth and endocrine effects of recombinant bovine growth hormone treatment in non-transgenic and growth hormone transgenic coho salmon
- 2012
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Ingår i: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480. ; 177:1, s. 143-152
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Tidskriftsartikel (refereegranskat)abstract
- To examine the relative growth, endocrine, and gene expression effects of growth hormone (GH) transgenesis vs. GH protein treatment, wild-type non-transgenic and GH transgenic coho salmon were treated with a sustained-release formulation of recombinant bovine GH (bGH; Posilac(TM)). Fish size, specific growth rate (SGR), and condition factor (CF) were monitored for 14 weeks, after which endocrine parameters were measured. Transgenic fish had much higher growth, SGR and CF than non-transgenic fish, and bGH injection significantly increased weight and SGR in non-transgenic but not transgenic fish. Plasma salmon GH concentrations decreased with bGH treatment in non-transgenic but not in transgenic fish where levels were similar to controls. Higher GH mRNA levels were detected in transgenic muscle and liver but no differences were observed in GH receptor (GHR) mRNA levels. In non-transgenic pituitary. GH and GHR mRNA levels per mg pituitary decreased with bGH dose to levels seen in transgenic salmon. Plasma IGF-I was elevated with bGH dose only in non-transgenic fish, while transgenic fish maintained an elevated level of IGF-I with or without bGH treatment. A similar trend was seen for liver IGF-I mRNA levels. Thus, bGH treatment increased fish growth and influenced feedback on endocrine parameters in non-transgenic but not in transgenic fish. A lack of further growth stimulation of GH transgenic fish suggests that these fish are experiencing maximal growth stimulation via GH pathways. Crown Copyright (C) 2012 Published by Elsevier Inc. All rights reserved.
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- Sundt-Hansen, Line, et al.
(författare)
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Growth enhanced brown trout show increased movement activity in the wild
- 2009
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Ingår i: FUNCTIONAL ECOLOGY. ; 23:3, s. 551-558
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Tidskriftsartikel (refereegranskat)abstract
- # 1. Rapid growth is often associated with several fitness-related benefits. However, in most organisms growth rates are rarely maximized, suggesting that trade-offs limit the benefits of rapid growth. To enable sustained high growth, behavioural modifications incurring costs may be required, and these may be responsible for evolution of sub-maximal growth rates. # 2. In a field experiment it was tested whether rapid growth in brown trout is achieved by increasing potentially costly movement activity. Causal relations were obtained by manipulating the growth rate using bovine growth hormone (GH) implants and monitoring movement activity of stream-dwelling brown trout for two months using radiotelemetry. # 3. GH-treated trout grew significantly faster than sham-treated trout both in terms of body mass and length. The GH-treated trout also had a significantly larger absolute movement during the experiment, moving about 68% more than the sham-treated trout. There were no GH effects on diel movement or home range between the two treatments. Plasma GH levels were lower in the GH-treated fish, indicating negative feedback inhibition of native GH secretion, and that the bovine GH implant was still functioning at the end of the study. # 4. This is the first study to show increased movement activity in GH-enhanced fish in the wild. Because increased movement is expected to lead to increased metabolic costs, the higher movement activity in the GH-treated trout was likely associated with increased foraging activity. The results demonstrate that increased movement activity is associated with rapid growth in brown trout. Such movement activity may be unfavourable under certain ecological conditions or life stages (i.e. high risk of predation or low resource levels), and may thus represent one component of the cost limiting evolution of maximum growth rates.
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- Sundt-Hansen, L., et al.
(författare)
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Growth hormone reduces growth in free-living Atlantic salmon fry
- 2012
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Ingår i: Functional Ecology. - : Wiley. - 0269-8463. ; 26:4, s. 904-911
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Tidskriftsartikel (refereegranskat)abstract
- 1. Although life-history theory predicts that juvenile growth rates should be high, there is substantial evidence that most juveniles grow below their physiological maximum. The endocrine system plays an important role in the determination of fundamental life-history traits, and hormones often serve as a link between an organisms environment and the expression of a trait. Particularly, growth is a life-history trait, which is strongly associated with growth hormone (GH) in fish, as well as most vertebrates. 2. To elucidate trade-offs related to elevated GH in fish in a natural environment, we experimentally administrated GH exogenously to juvenile Atlantic salmon using sustained-release GH implants, at an earlier ontogenetic stage than previously achieved (1.5 months). We assessed the effects on growth, dispersal and survival in contrasting environments. 3. Exogenous GH treatment increased the growth rate when fish were fed ad libitum in captivity. However, in a natural stream, GH treatment had a significant negative effect on growth and no apparent effect on survival or dispersal. This contrasts with previous studies conducted at later developmental stages, which show either a positive growth effect or no effect of elevated GH levels. 4. This study shows that environmental conditions strongly affect the response to GH and that under some natural conditions, it may also reduce growth. We suggest that the endogenous plasma GH levels may be maximizing growth during early, but not later, juvenile stages in nature.
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