The main objective of the project was to test new local raw materials for aquaculture feed and to... more The main objective of the project was to test new local raw materials for aquaculture feed and to implement those into the production chain, thereby:moving the Nordic aquaculture industry towards a ...
Sixth International Symposium on Fish Endocrinology Program and Abstract Book, 2008
The Atlantic halibut is a large, cold-water flatfish which inhabits the North Atlantic. The pelag... more The Atlantic halibut is a large, cold-water flatfish which inhabits the North Atlantic. The pelagic and symmetric larvae undergo metamorphosis as an adaptation to better suit them for a benthic life. Metamorphosis involves many dramatic biological changes including a major reconstruction of the cranium during which the left eye migrates to the right side of the head. The structural driving force of eye migration is assumed to be the growth and migration of the ethmoid plate and the migration of the frontal processes towards the future ocular side, and fibroblast proliferation ventrally to the migrating eye. Metamorphosis is under endocrine control and thyroid hormones are known to be the main regulatory hormones. Data on the role of other growth regulators, including the growth hormone (GH) - insulin-like growth factor I (IGF-I) system, in halibut metamorphosis are sparse. GH content in the head region increases steadily from first feeding throughout the larval phase until post-metamorphosis, while IGF-I content in the body increases until the onset of metamorphosis and decline thereafter. In situ hybridization and immunohistochemistry reveal that mRNA and proteins of the type I GH receptor (GHR), and mRNA of the type II GHR and the IGF-I receptor (IGF-IR) are expressed in fibroblasts in soft tissue between the eyes, frontal bone osteocytes and dorsal cranial chondrocytes during the metamorphic process. In fibroblasts and chondrocytes, the expression appears most intense at the start of metamorphosis (stage 8) and decreases during subsequent developmental stages. IGF-IR expression decreases in frontal bone osteocytes after the completion of metamorphosis (stage 10). The decrease in tissue IGF-I content during metamorphosis, and the localization and change in abundance of GHRs and IGF-IR in head structures undergoing reconstruction, indicate the involvement of the GH-IGF-I system in Atlantic halibut metamorphosis. Acknowledgement: Work financed by the Commission of the European Communities within the project “Arrested development: the molecular and endocrine basis of flatfish metamorphosis” (Q5RS-2002-01192).
Leptin (Lep) is an anorexigenic hormone and regulates appetite-related neuropeptides in mammals. ... more Leptin (Lep) is an anorexigenic hormone and regulates appetite-related neuropeptides in mammals. A number of neuropeptides have also been linked to appetite regulation of teleost fish, but Lep signaling activation and effects on appetite-regulating neurons are poorly elucidated in early vertebrates. This study uses cellular, tissue and organismal approaches to elucidate the acute, central Lep action in rainbow trout. The results demonstrate that Lep activates phosphorylation of protein kinase B (Akt) and signal transducer and activator of transcription 3 in rainbow trout hypothalamus-derived cells, and that the phosphatidylinositol 3-kinase (Pi3k) inhibitor LY294002 can suppress the Lep-induced Akt phosphorylation. Intracerebroventricular (ICV) Lep administration strongly suppresses food intake at the doses of 0.05 and 0.5 µg Lep fish(-1). At low dose, Lep stimulates hypothalamic transcription of anorexigenic cocaine- and amphetamine-regulated transcript (Cart) and orexigenic neurop...
This is a report published in Swedish by Aquaculture Centre West (Vattenbrukscentrum Väst) at the... more This is a report published in Swedish by Aquaculture Centre West (Vattenbrukscentrum Väst) at the University of Gothenburg. It presents an analysis, based on economic and biological selection criteria, on which marine fish species could be successful candidate species for marine aquaculture on the Swedish west coast.
Thyroid hormones transiently increase during parr-smolt transformation in coho salmon, Oncorhynch... more Thyroid hormones transiently increase during parr-smolt transformation in coho salmon, Oncorhynchus kisutch, and are believed to trigger morphological, physiological, behavioural, and neural changes. The effectiveness of propylthiouracil (PTU) to induce hypothyroidism in smolting coho salmon was determined by immersing coho salmon, Oncorhynchus kisutch, in 30 mg l-1 PTU from May 1, two weeks prior to the consistent annual total thyroxine
... less than 100 tons per year, although overall the trend is toward an increased ... Growth and... more ... less than 100 tons per year, although overall the trend is toward an increased ... Growth and age at first maturity in turbot and halibut reared under different photoperiods. ... The impact of nutrition on metamorphosis in Atlantic halibut (Hippoglossus hippoglossus L.). Aquaculture , 250 ...
Cholecystokinin (CCK) and gastrin-releasing peptide (GRP) are gastrointestinal peptides thought t... more Cholecystokinin (CCK) and gastrin-releasing peptide (GRP) are gastrointestinal peptides thought to be important regulators of intake and digestion of food in vertebrates. In this study, pre- and postprandial plasma levels of CCK and GRP were measured in rainbow trout (Oncorhynchus mykiss) by the establishment of homologous radioimmunoassays, and the hormonal levels assessed in relation to dietary lipid:protein ratio and food intake. Fish were acclimated to either a high protein/low lipid diet (HP/LL diet; 14.1% lipids) or a normal protein/high lipid diet (NP/HL diet; 31.4% lipids). On three consecutive sampling days, radio-dense lead-glass beads were included in the diets for assessment of feed intake. Fish were terminally sampled for blood and stomach contents prior to feeding at time 0, and at 0.3, 1, 2, 4, 6, and 24 h after feeding. There was a postprandial elevation of plasma CCK levels, which was most evident after 4 and 6 h. Fish fed the NP/HL diet had higher plasma CCK levels compared with those fed the HP/LL diet. Plasma CCK levels were not affected by the amount of food ingested. GRP levels in plasma were not influenced by sampling time, diet, or feed intake. The results indicate that the endocrine release of gastrointestinal CCK is increased during feeding and may be further influenced by the dietary lipid:protein ratio in rainbow trout. Plasma GRP levels, on the other hand, appear not to be influenced by feeding or diet composition.
Ghrelin stimulates pituitary growth hormone (GH) release, and has a key role in the regulation of... more Ghrelin stimulates pituitary growth hormone (GH) release, and has a key role in the regulation of food intake and adiposity in vertebrates. To investigate the central effect of native rainbow trout ghrelin (rtghrelin) on food intake in rainbow trout, as well as its possible mode of action, four groups of fish received a single injection into the third brain ventricle (i.c.v. injection): (1) control group (physiological saline) (2) ghrelin-treated group (2.0 ng rtghrelin g bwt(-1)), (3) group given the corticotropin-releasing hormone receptor antagonist alpha-helical CRF 9-41 (ahCRF) (4.0 ng g bwt(-1)) and (4) group receiving the same dose of both ghrelin and ahCRF. Food intake was assessed 1h after treatment. In addition, the presence of the GHS-R (the ghrelin receptor) in the rainbow trout CNS was examined with Western blot. To investigate peripheral effects of ghrelin, rainbow trout received an intraperitoneal cholesterol-based implant with or without rtghrelin, and daily food intake was measured during 14 days. Weight and length were measured at the start and termination of the experiment and specific growth rates were calculated. Mesenteric fat stores, muscle and liver lipid content were analysed after the treatment period. Central ghrelin injections decreased food intake compared with controls, and treatment with ahCRF abolished the ghrelin-effect. Western blot analysis of the GHS-R revealed a single band at around 60 kDa in pituitary, hypothalamus, brain and stomach. Long-term peripheral ghrelin treatment decreased daily food intake compared with controls. This was reflected in a ghrelin-induced decrease in weight growth rate (p<0.06). There was no effect of ghrelin on plasma GH levels or tissue fat stores. The conclusion from this study is that the GHS-R is indicated in the CNS in rainbow trout and that ghrelin may act there as an anorexigenic hormone, through a CRF-mediated pathway. Elevated peripheral ghrelin levels also seem to lead to decreased feed intake in the longer term.
The present study was conducted to establish a homologous radioimmunoassay (RIA) for quantifying ... more The present study was conducted to establish a homologous radioimmunoassay (RIA) for quantifying plasma leptin (Lep) levels in salmonid species, and to study Lep levels in relation to nutritional status. A part of the Lep peptide, a 14 amino acid long sequence, identical between a Salmo and an Oncorhynchus species was synthesised. Polyclonal antibodies were raised in rabbit against this antigen and both were subsequently used in the development of a RIA protocol for assessing plasma Lep levels. The limit of detection of the assay was 0.3 nM, and intra- and interassay coefficient of variation (CV) were 8.4% and 13%, respectively. Apart from Atlantic salmon and rainbow trout, the assay exhibits measuring parallelism for a range of fish species, including arctic char, Atlantic cod and turbot, suggesting that the established RIA is useful for quantifying Lep levels in several fish species. The RIA indicates that Lep is found in salmonid plasma at levels of 0.5-5 nM, which is comparable with other peptide hormones, and well within the measuring range of the RIA. A study of fed and fasted rainbow trout showed elevated plasma Lep levels during fasting. In addition there was no correlation between Lep levels and condition factor. These data suggest that the relation between circulating Lep levels and energy status differs from that in mammals. While Lep is linked to energy balance, it may not act as an adiposity signal in salmonids, possibly pointing to functional divergence among ectothermic and endothermic vertebrates.
The main objective of the project was to test new local raw materials for aquaculture feed and to... more The main objective of the project was to test new local raw materials for aquaculture feed and to implement those into the production chain, thereby:moving the Nordic aquaculture industry towards a ...
Sixth International Symposium on Fish Endocrinology Program and Abstract Book, 2008
The Atlantic halibut is a large, cold-water flatfish which inhabits the North Atlantic. The pelag... more The Atlantic halibut is a large, cold-water flatfish which inhabits the North Atlantic. The pelagic and symmetric larvae undergo metamorphosis as an adaptation to better suit them for a benthic life. Metamorphosis involves many dramatic biological changes including a major reconstruction of the cranium during which the left eye migrates to the right side of the head. The structural driving force of eye migration is assumed to be the growth and migration of the ethmoid plate and the migration of the frontal processes towards the future ocular side, and fibroblast proliferation ventrally to the migrating eye. Metamorphosis is under endocrine control and thyroid hormones are known to be the main regulatory hormones. Data on the role of other growth regulators, including the growth hormone (GH) - insulin-like growth factor I (IGF-I) system, in halibut metamorphosis are sparse. GH content in the head region increases steadily from first feeding throughout the larval phase until post-metamorphosis, while IGF-I content in the body increases until the onset of metamorphosis and decline thereafter. In situ hybridization and immunohistochemistry reveal that mRNA and proteins of the type I GH receptor (GHR), and mRNA of the type II GHR and the IGF-I receptor (IGF-IR) are expressed in fibroblasts in soft tissue between the eyes, frontal bone osteocytes and dorsal cranial chondrocytes during the metamorphic process. In fibroblasts and chondrocytes, the expression appears most intense at the start of metamorphosis (stage 8) and decreases during subsequent developmental stages. IGF-IR expression decreases in frontal bone osteocytes after the completion of metamorphosis (stage 10). The decrease in tissue IGF-I content during metamorphosis, and the localization and change in abundance of GHRs and IGF-IR in head structures undergoing reconstruction, indicate the involvement of the GH-IGF-I system in Atlantic halibut metamorphosis. Acknowledgement: Work financed by the Commission of the European Communities within the project “Arrested development: the molecular and endocrine basis of flatfish metamorphosis” (Q5RS-2002-01192).
Leptin (Lep) is an anorexigenic hormone and regulates appetite-related neuropeptides in mammals. ... more Leptin (Lep) is an anorexigenic hormone and regulates appetite-related neuropeptides in mammals. A number of neuropeptides have also been linked to appetite regulation of teleost fish, but Lep signaling activation and effects on appetite-regulating neurons are poorly elucidated in early vertebrates. This study uses cellular, tissue and organismal approaches to elucidate the acute, central Lep action in rainbow trout. The results demonstrate that Lep activates phosphorylation of protein kinase B (Akt) and signal transducer and activator of transcription 3 in rainbow trout hypothalamus-derived cells, and that the phosphatidylinositol 3-kinase (Pi3k) inhibitor LY294002 can suppress the Lep-induced Akt phosphorylation. Intracerebroventricular (ICV) Lep administration strongly suppresses food intake at the doses of 0.05 and 0.5 µg Lep fish(-1). At low dose, Lep stimulates hypothalamic transcription of anorexigenic cocaine- and amphetamine-regulated transcript (Cart) and orexigenic neurop...
This is a report published in Swedish by Aquaculture Centre West (Vattenbrukscentrum Väst) at the... more This is a report published in Swedish by Aquaculture Centre West (Vattenbrukscentrum Väst) at the University of Gothenburg. It presents an analysis, based on economic and biological selection criteria, on which marine fish species could be successful candidate species for marine aquaculture on the Swedish west coast.
Thyroid hormones transiently increase during parr-smolt transformation in coho salmon, Oncorhynch... more Thyroid hormones transiently increase during parr-smolt transformation in coho salmon, Oncorhynchus kisutch, and are believed to trigger morphological, physiological, behavioural, and neural changes. The effectiveness of propylthiouracil (PTU) to induce hypothyroidism in smolting coho salmon was determined by immersing coho salmon, Oncorhynchus kisutch, in 30 mg l-1 PTU from May 1, two weeks prior to the consistent annual total thyroxine
... less than 100 tons per year, although overall the trend is toward an increased ... Growth and... more ... less than 100 tons per year, although overall the trend is toward an increased ... Growth and age at first maturity in turbot and halibut reared under different photoperiods. ... The impact of nutrition on metamorphosis in Atlantic halibut (Hippoglossus hippoglossus L.). Aquaculture , 250 ...
Cholecystokinin (CCK) and gastrin-releasing peptide (GRP) are gastrointestinal peptides thought t... more Cholecystokinin (CCK) and gastrin-releasing peptide (GRP) are gastrointestinal peptides thought to be important regulators of intake and digestion of food in vertebrates. In this study, pre- and postprandial plasma levels of CCK and GRP were measured in rainbow trout (Oncorhynchus mykiss) by the establishment of homologous radioimmunoassays, and the hormonal levels assessed in relation to dietary lipid:protein ratio and food intake. Fish were acclimated to either a high protein/low lipid diet (HP/LL diet; 14.1% lipids) or a normal protein/high lipid diet (NP/HL diet; 31.4% lipids). On three consecutive sampling days, radio-dense lead-glass beads were included in the diets for assessment of feed intake. Fish were terminally sampled for blood and stomach contents prior to feeding at time 0, and at 0.3, 1, 2, 4, 6, and 24 h after feeding. There was a postprandial elevation of plasma CCK levels, which was most evident after 4 and 6 h. Fish fed the NP/HL diet had higher plasma CCK levels compared with those fed the HP/LL diet. Plasma CCK levels were not affected by the amount of food ingested. GRP levels in plasma were not influenced by sampling time, diet, or feed intake. The results indicate that the endocrine release of gastrointestinal CCK is increased during feeding and may be further influenced by the dietary lipid:protein ratio in rainbow trout. Plasma GRP levels, on the other hand, appear not to be influenced by feeding or diet composition.
Ghrelin stimulates pituitary growth hormone (GH) release, and has a key role in the regulation of... more Ghrelin stimulates pituitary growth hormone (GH) release, and has a key role in the regulation of food intake and adiposity in vertebrates. To investigate the central effect of native rainbow trout ghrelin (rtghrelin) on food intake in rainbow trout, as well as its possible mode of action, four groups of fish received a single injection into the third brain ventricle (i.c.v. injection): (1) control group (physiological saline) (2) ghrelin-treated group (2.0 ng rtghrelin g bwt(-1)), (3) group given the corticotropin-releasing hormone receptor antagonist alpha-helical CRF 9-41 (ahCRF) (4.0 ng g bwt(-1)) and (4) group receiving the same dose of both ghrelin and ahCRF. Food intake was assessed 1h after treatment. In addition, the presence of the GHS-R (the ghrelin receptor) in the rainbow trout CNS was examined with Western blot. To investigate peripheral effects of ghrelin, rainbow trout received an intraperitoneal cholesterol-based implant with or without rtghrelin, and daily food intake was measured during 14 days. Weight and length were measured at the start and termination of the experiment and specific growth rates were calculated. Mesenteric fat stores, muscle and liver lipid content were analysed after the treatment period. Central ghrelin injections decreased food intake compared with controls, and treatment with ahCRF abolished the ghrelin-effect. Western blot analysis of the GHS-R revealed a single band at around 60 kDa in pituitary, hypothalamus, brain and stomach. Long-term peripheral ghrelin treatment decreased daily food intake compared with controls. This was reflected in a ghrelin-induced decrease in weight growth rate (p<0.06). There was no effect of ghrelin on plasma GH levels or tissue fat stores. The conclusion from this study is that the GHS-R is indicated in the CNS in rainbow trout and that ghrelin may act there as an anorexigenic hormone, through a CRF-mediated pathway. Elevated peripheral ghrelin levels also seem to lead to decreased feed intake in the longer term.
The present study was conducted to establish a homologous radioimmunoassay (RIA) for quantifying ... more The present study was conducted to establish a homologous radioimmunoassay (RIA) for quantifying plasma leptin (Lep) levels in salmonid species, and to study Lep levels in relation to nutritional status. A part of the Lep peptide, a 14 amino acid long sequence, identical between a Salmo and an Oncorhynchus species was synthesised. Polyclonal antibodies were raised in rabbit against this antigen and both were subsequently used in the development of a RIA protocol for assessing plasma Lep levels. The limit of detection of the assay was 0.3 nM, and intra- and interassay coefficient of variation (CV) were 8.4% and 13%, respectively. Apart from Atlantic salmon and rainbow trout, the assay exhibits measuring parallelism for a range of fish species, including arctic char, Atlantic cod and turbot, suggesting that the established RIA is useful for quantifying Lep levels in several fish species. The RIA indicates that Lep is found in salmonid plasma at levels of 0.5-5 nM, which is comparable with other peptide hormones, and well within the measuring range of the RIA. A study of fed and fasted rainbow trout showed elevated plasma Lep levels during fasting. In addition there was no correlation between Lep levels and condition factor. These data suggest that the relation between circulating Lep levels and energy status differs from that in mammals. While Lep is linked to energy balance, it may not act as an adiposity signal in salmonids, possibly pointing to functional divergence among ectothermic and endothermic vertebrates.
Uploads
Papers by Björn Björnsson