| 1. |
- Birgersson, Lina, 1989, et al.
(författare)
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Thyroid function and immune status in perch (Perca fluviatilis) from lakes contaminated with PFASs or PCBs
- 2021
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Ingår i: Ecotoxicology and Environmental Safety. - : Elsevier BV. - 0147-6513 .- 1090-2414. ; 222
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Tidskriftsartikel (refereegranskat)abstract
- The environment contains a multitude of man-made chemicals, some of which can act as endocrine disruptors (EDCs), while others can be immunotoxic. We evaluated thyroid disruption and immunotoxic effects in wild female perch (Perca fluviatilis) collected from two contaminated areas in Sweden; one site contaminated with perand polyfluoroalkyl substances (PFASs) and two sites contaminated with polychlorinated biphenyls (PCBs), with one reference site included for each area. The hepatic mRNA expression of thyroid receptors alpha and beta, and the thyroid hormone metabolising iodothyronine deiodinases (dio1, dio2 and dio3) were measured using real-time PCR, while the levels of thyroid hormone T3 in plasma was analysed using a radioimmunoassay. In addition, lymphocytes, granulocytes, and thrombocytes were counted microscopically. Our results showed lower levels of T3 as well as lower amounts of lymphocytes and granulocytes in perch collected from the PFAS-contaminated site compared to reference sites. In addition, expressions of mRNA coding for thyroid hormone metabolising enzymes (dio2 and dio3) and thyroid receptor alpha (thra) were significantly different in these fish compared to their reference site. For perch collected at the two PCB-contaminated sites, there were no significant differences in T3 levels or in expression levels of the thyroid-related genes, compared to the reference fish. Fish from one of the PCB-contaminated sites had higher levels of thrombocytes compared with both the second PCB lake and their reference lake; hence PCBs are unlikely to be the cause of this effect. The current study suggests that lifelong exposure to PFASs could affect both the thyroid hormone status and immune defence of perch in the wild.
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| 2. |
- Bresolin de Souza, Karine, et al.
(författare)
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Increased activity of lysozyme and complement system in Atlantic halibut exposed to elevated CO2 at six different temperatures.
- 2016
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Ingår i: Marine environmental research. - : Elsevier BV. - 1879-0291 .- 0141-1136. ; 122, s. 143-147
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Tidskriftsartikel (refereegranskat)abstract
- Ocean acidification and rising seawater temperature are environmental stressors resulting from the continuous increase of the atmospheric CO2 concentration due to anthropogenic activities. As a consequence, marine fish are expected to undergo conditions outside of their tolerance range, leading to physiological challenges with possible detrimental implications. Our research group has previously shown that exposure to elevated CO2 modulated the immune system of the Atlantic halibut. To further investigate this finding, we analysed non-specific immune components in blood plasma of Atlantic halibut (Hippoglossus hippoglossus) juveniles acclimated to six different temperatures (5, 10, 12, 14, 16 and 18°C), and to water pH of 8.0 (control) or 7.6 (predicted for year 2100) for three months. Plasma ions (K(+), Na(+), Ca(++), Cl(-)) and lactate concentrations were also measured. The analysis of plasma ions did not show any trends related to temperature or CO2 exposure, and the majority of the experimental fish were able to maintain ionic balance. The results show that both innate immune components (lysozyme and alternative complement system) had increased activities in response to elevated CO2, representing a CO2-related impact on the halibut's immune system. The increased activity of lysozyme and complement system is possibly part of the acclimatization process, and might be protective.
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| 3. |
- Frenzilli, Giada, et al.
(författare)
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Bisphenol A and Bisphenol S Induce Endocrine and Chromosomal Alterations in Brown Trout
- 2021
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Ingår i: Frontiers in endocrinology. - : Frontiers Media SA. - 1664-2392. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Bisphenol A is a widely used compound found in large amount of consumer products. As concerns have been raised about its toxicological and public health effect, the use of alternatives to bisphenol A are now increasing. Bisphenol S is one of the analogues being used as a replacement for bisphenol A despite the fact that little is known about the effects of bisphenol S on living organisms. In this study, we investigated the potential endocrine and genotoxic effects of bisphenol A and bisphenol S in juvenile brown trout (Salmo trutta). The fish were exposed to the compounds for either 2 weeks or 8 weeks via sustained-release cholesterol implants containing doses of 2 mg/kg fish or 20 mg/kg fish of the substances. The effects on the thyroid hormone levels and the estrogenic disrupting marker vitellogenin were evaluated, along with the genotoxic markers micronucleated cells and erythrocyte nuclear abnormalities. An increase in plasma vitellogenin was observed in fish exposed to the high dose of bisphenol A for 2 weeks. At this experimental time the level of the thyroid hormone triiodothyronine (T3) in plasma was elevated after bisphenol S exposure at the high concentration, and paralleled by an increase of micronucleated cells. Moreover, bisphenol A induced an increase of micronuclei frequency in fish erythrocytes after the exposure at the lowest dose tested. Taken together the results indicate that both bisphenol A and its alternative bisphenol S cause endocrine disrupting and genotoxic effects in brown trout, although suggesting two different mechanisms of damage underlying bisphenol A and bisphenol S activity.
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| 4. |
- Gräns, Albin, 1979, et al.
(författare)
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Aerobic scope fails to explain the detrimental effects on growth resulting from warming and elevated CO2 in Atlantic halibut
- 2014
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 217:5, s. 711-717
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Tidskriftsartikel (refereegranskat)abstract
- As a consequence of increasing atmospheric CO2, the world's oceans are becoming warmer and more acidic. Whilst the ecological effects of these changes are poorly understood, it has been suggested that fish performance including growth will be reduced mainly as a result of limitations in oxygen transport capacity. Contrary to the predictions given by the oxygen- and capacity-limited thermal tolerance hypothesis, we show that aerobic scope and cardiac performance of Atlantic halibut (Hippoglossus hippoglossus) increase following 14–16 weeks exposure to elevated temperatures and even more so in combination with CO2-acidified seawater. However, the increase does not translate into improved growth, demonstrating that oxygen uptake is not the limiting factor for growth performance at high temperatures. Instead, long-term exposure to CO2-acidified seawater reduces growth at temperatures that are frequently encountered by this species in nature, indicating that elevated atmospheric CO2 levels may have serious implications on fish populations in the future.
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| 5. |
- Hedén, Ida, 1984, et al.
(författare)
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Dietary replacement of fishmeal with marine proteins recovered from shrimp and herring process waters promising in Atlantic salmon aquaculture
- 2023
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Ingår i: Aquaculture. - 0044-8486. ; 574
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Tidskriftsartikel (refereegranskat)abstract
- There is a general agreement that fish meal (FM) and fish oil (FO) are valuable resources for aquafeed, but that the production cannot keep the same pace as the current growth of the aquaculture industry. Therefore, there is a need to find alternative sources for lipids and protein. This study examines the possibility of using proteins recovered from seafood industry side stream waters as a complement to FM in feed for Atlantic salmon. To recover the proteins, herring and shrimp process side streams waters were flocculated then treated with dissolved air flotation (DAF), which is considered a gentle technology. Shrimp steam water was used to obtain shrimp protein (SP) and herring salt brine to obtain herring protein (HP). The recovered semi-solid protein fraction was spray dried and formulated into experimental diets at inclusion levels of 1.9–10% (dw/dw). Two feeding trials were conducted to investigate; 1) the properties of different flocculants to recover SP from shrimp steam water, alginate (Alg; 1.9% inclusion), carrageenan (Carr; 2.0% inclusion) and a synthetic flocculant from Kemira (Kem; 3.8% inclusion). 2) total or partial replacement of FM with SP-Alg (10% and no FM) and HP-Alg (3% and 8% FM). For both feeding trials each diet was provided to triplicate tanks (n = 31 and 30/tank) of Atlantic salmon with a start weight of 193 g (duration 10 weeks) and 304 g (duration 7 weeks) respectively. All fish showed similar feed intake, feed conversion ratio (on tank basis) and weight gain. The inclusion of SP or HP as total or partial replacement of FM did neither influence adiposity of the fish, as measured by condition factor, nor heposomatic index (HSI). No negative effect of the alternative protein could be found through histological examination of the intestine. In feeding trial two, diets did not affect the adaptive immune indicators CD8α and MHC II. The SP-Alg diet did not affect intestinal barrier and transporting functions, assessed using Ussing-chamber technology. However, HP-Alg affected the trans-epithelial resistance, which indicate that the intestinal barrier function could be affected by low inclusions. We conclude that from a biological perspective, SP recovered from shrimp steaming waters using Alg and DAF technology represents a new marine biomass with potential as a replacement for FM in Atlantic salmon feed. To diversify the possibility of using flocculants to retrieve proteins we also suggest further investigation of the potential to use Carr in larger inclusions.
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| 6. |
- Hinchcliffe, James, 1992, et al.
(författare)
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Aquafeed ingredient production from herring (Clupea harengus) by-products using pH-shift processing: Effect from by-product combinations, protein solubilization-pH and centrifugation force
- 2019
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Ingår i: Animal Feed Science and Technology. - : Elsevier BV. - 0377-8401. ; 247, s. 273-284
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Tidskriftsartikel (refereegranskat)abstract
- There is a strong need in animal production for sustainable protein sources used in feed. The aim of the present study was to evaluate the potential of the pH-shift process as a method to concentrate proteins from complex bone-rich herring (Clupea harengus) by-products. By-product parts (frame, head, guts), protein solubilization pH (pH 2.8 or 11.3) and separation g-force (800 or 8000 g) were varied. The findings revealed that protein recovery yields of up to 60% were obtained and that higher protein yield was obtained from the alkaline than the acid process. By-product part and g-force had no significant impact on protein yield. Protein levels reached in the concentrates were 75–80 % (dw basis). Protein concentrates contained a similar amino acid profile as have been reported for fishmeal, with ~40% essential amino acids and up to 7.8% and 2.8% of lysine and methionine. Residual levels of LC n-3 PUFA as well as calcium, magnesium, potassium and phosphorous were also found in the produced protein concentrates which could be an added value. Acid produced concentrates were particularly high in calcium potassium and phosphorous. Provided a careful evaluation, the pH-shift process could become a successful alternative to classic fish meal production for increasing the use of fish by-products for production of protein ingredients for feed. © 2018 Elsevier B.V.
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| 7. |
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| 8. |
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| 9. |
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| 10. |
- Kling, Peter, 1968, et al.
(författare)
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The role of GH in lipid homeostasis, energy utilization and partitioning in rainbow trout: interactions with ghrelin, leptin and insulin-like growth factor I
- 2012
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Ingår i: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480. ; 175:1, s. 153-162
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Tidskriftsartikel (refereegranskat)abstract
- The growth-promoting effects of in vivo growth hormone (GH) treatment were studied in relation to size and lipid content of energy stores including liver, mesentery, white muscle and belly flap in rainbow trout. In order to elucidate endocrine interactions and links to regulation of growth, adiposity and energy metabolism, plasma levels of GH, insulin-like growth factor I (IGF-I), leptin (Lep) and ghrelin, were assessed and correlated to growth and energy status. In addition tissue-specific expression of lepa1 mRNA was examined. Juvenile rainbow trout were implanted with sustained-release bovine GH implants and terminally sub-sampled at 1, 3 and 6 weeks. GH increased specific growth rate, reduced condition factor (CF) and increased feed conversion efficiency resulting in a redistribution of energy stores. Thus, GH decreased mesenteric (MSI) and liver somatic index (LSI). Lipid content of the belly flap increased following GH-treatment while liver and muscle lipid content decreased. Independent of GH substantial growth was accompanied by an increase in muscle lipids and a decrease in belly flap lipids. The data suggest that the belly flap may function as an energy buffering tissue during episodes of feeding and lean growth. Liver and muscle lipids were positively correlated to body weight, indicating a size-dependent change in adiposity. Hepatic lepa1 mRNA positively correlated to MSI and CF and its expression decreased following GH treatment, coinciding with decreased hepatic lipid content. Plasma Lep was positively correlated to MSI and belly flap lipid content, suggesting that Lep may communicate energy status. In summary, the observed GH tissue-specific effects on lipid metabolism in rainbow trout highlight the complex physiology of the energy reserves and their endocrine control.
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| 11. |
- Kullgren, Andreas, 1977, et al.
(författare)
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The impact of temperature on the metabolome and endocrine metabolic signals in Atlantic salmon (Salmo salar)
- 2013
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Ingår i: Comparative Biochemistry and Physiology A. - : Elsevier BV. - 1095-6433 .- 1531-4332. ; 164:1, s. 44-53
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Tidskriftsartikel (refereegranskat)abstract
- The aim was to elucidate the effects of elevated temperature on growth performance, growth- and appetite-regulating hormones and metabolism in Atlantic salmon, Salmo salar. Post-smolts in seawater (average mass 175 g) that had been reared at 12 °C were kept at three temperatures (8, 12 and 18 °C) and sampled after one and three months. After three months, the fish kept in 18 °C had decreased growth rate and condition factor, and elevated plasma levels of growth hormone (GH) and leptin, compared with fish kept at the lower temperatures. Food conversion efficiency was also decreased at 18 °C, while at the same time protein uptake was improved and thus was not a limiting mechanism for growth. Redistribution of energy stores in fish at the highest temperature is evident as a preference of maintaining length growth during times of limited energy availability. NMR-based metabolomics analyses of plasma revealed that several metabolites involved in energy metabolism were negatively affected by temperature in the upper temperature range of Atlantic salmon. Specifically, the high temperature induced a decline of several amino acids (glutamine, tyrosine and phenylalanine) and a shift in lipid metabolism. It appears likely that the decreased food intake at the highest temperature is linked to an anorexigenic function of leptin, but also that the decreased food intake, feed conversion efficiency and condition factor can be linked to changes in GH endocrinology.
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| 12. |
- Olsson, Catharina, 1968, et al.
(författare)
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Identification of genes for the ghrelin and motilin receptors and a novel related gene in fish, and stimulation of intestinal motility in zebrafish (Danio rerio) by ghrelin and motilin.
- 2008
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Ingår i: General and comparative endocrinology. - : Elsevier BV. - 0016-6480. ; 155:1, s. 217-26
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Tidskriftsartikel (refereegranskat)abstract
- In mammals ghrelin has a diverse range of effects including stimulation of gut motility but although present in teleost fish its effects on motility have not been investigated. The present study used bioinformatics to search for fish paralogues of the ghrelin receptor and the closely related motilin receptor, and investigated the effects of ghrelin and motilin on gut motility in zebrafish, Danio rerio. Fish paralogues of the human ghrelin and motilin receptor genes were identified, including those from the zebrafish. In addition, a third gene was identified in three species of pufferfish (the only fish genome completely sequenced), which is distinct from the ghrelin and motilin receptors but more closely aligned to these receptors relative to other G-protein coupled receptors. Immunohistochemistry demonstrated strong ghrelin receptor-like reactivity in the muscle of the zebrafish intestine. In isolated intestinal bulb and mid/distal intestine preparations, ghrelin, motilin, and the motilin receptor agonist erythromycin all evoked contraction; these responses ranged between 9% and 51% of the contractions evoked by carbachol (10(-6) M). There were some variations in the concentrations found to be active in the different tissues, e.g., whereas motilin and rat ghrelin caused contraction of the intestinal bulb circular muscle at concentrations as low as 10(-8) M, human ghrelin (10(-8) to 10(-6) M) was without activity. Neither ghrelin (10(-7) M) nor erythromycin (10(-5) M) affected the contractions evoked by electrical field stimulation. The results suggest that both ghrelin and motilin can regulate intestinal motility in zebrafish and most likely other teleosts, and are discussed in relation to the evolution of these regulatory peptides.
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| 13. |
- Aksnes, A, et al.
(författare)
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Size-fractionated fish hydrolysate as feed ingredient for rainbow trout (Oncorhynchus mykiss) fed high plant protein diets. I: Growth, growth regulation and feed utilization
- 2006
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Ingår i: Aquaculture. - : Elsevier BV. - 0044-8486. ; 261:1, s. 305-317
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Tidskriftsartikel (refereegranskat)abstract
- Six experimental diets were fed to rainbow trout to examine the effect of fish hydrolysate and ultra filtered fish hydrolysate on growth performance, feed utilization and growth regulation using diets low in dietary fish meal inclusion. One diet contained a high level of plant protein sources (90.6% of total dietary protein) and a low level of fish meal (9.4% of dietary protein). Two diets contained different levels of hydrolysate in exchange for the plant protein sources, reducing the plant protein level to 73.9% and 57.2%, respectively. Two further diets were identical in composition except that the hydrolysate was ultra filtered to remove low molecular weight compounds. A moderate level of fish meal was used in the sixth diet which had a dietary plant protein level of 57.0%. All diets were made equal in protein, lipid, energy and lysine. The feeding trial lasted for 90 days and for the fastest growing group, fed moderate level of fish meal, the fish increased in weight from 149 g at start to a final weight of 443 g. All groups showed significant differences in growth and feed utilizations. Specific growth rates were; 0.30% day− 1 for the plant protein diet, 0.98% day− 1 for the high hydrolysate diet, 0.72% day− 1 for the group containing the high level of ultra filtered hydrolysate, and 1.21% day− 1 for the moderate fish meal diet. Feed efficiencies (g fish weight gain per g feed intake) were found to be 0.57 for plant protein diet, 0.97 for high level of hydrolysate, 0.83 for ultra filtered hydrolysate and 1.03 for the moderate fish meal diet. Half dietary inclusions of hydrolysate and ultra filtered hydrolysate revealed values between the plant protein diets and high levels of these ingredients, respectively. Feed consumption in percentage of average fish weight per day, correlated with the feed efficiency for all groups. PER, PPV and BV correlated with the differences in growth. Protein digestibilities were equal for all groups, while the moderate fish meal diet showed higher lipid and energy digestibilities than the plant protein diets. Although some of the differences may be due to growth inhibitors in plant resources other explanations may be relevant. Plasma growth hormone (GH) levels were significantly higher in fish fed the plant protein diet than fish fed the fish meal or high hydrolysate diet, which is most likely a result of their poor feeding status. Plasma IGF-I levels were not affected by diet. Comparisons of groups with similar inclusion of plant ingredients, and thus equal level of growth inhibitors, show that in removing small molecular weight compounds from fish hydrolysate, the growth and feed efficiency were significantly reduced. Some of these small compounds in fish hydrolysate thus seem to be essential for biological performance. Further, as fish meal revealed the best performance, fish muscle protein is not the only nutrient that makes fish meal an essential ingredient in aqua feed for carnivorous fish. This information is important in the work to find replacement of fish meal in a sustainable growing global aquaculture industry.
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| 14. |
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| 15. |
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| 16. |
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| 17. |
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| 18. |
- Björnsson, Björn Thrandur, 1952, et al.
(författare)
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Growth hormone endocrinology of salmonids: regulatory mechanisms and mode of action
- 2002
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Ingår i: FISH PHYSIOLOGY AND BIOCHEMISTRY. - 0920-1742. ; 27:3-4, s. 227-242
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Tidskriftsartikel (refereegranskat)abstract
- The focus of this review is on the regulatory mechanisms and the mode of action of GH in salmonids. To stimulate further research, it aims at highlighting areas where numerous important breakthroughs have recently been made, as well as where data are currently lacking. The regulation of GH secretion is under complex hypothalamic control, as well as under negative feedback control by GH and IGF-I. Further, the recently characterized ghrelin is a potent GH secretagogue, and may prove to be a link between feed intake and growth regulation. GH plasma profiles show indications of diurnal changes, but whether salmonids have true pulsatile GH secretion remains to be elucidated. The recent cloning and characterization of the salmon GH receptor (GHR) is a major research break-through which will give new insights into the mechanisms of GH action. It should also stimulate research into circulating GH-binding proteins (GHBPs), as they appear to be a soluble form of the GHR. The salmonid GHR sequences show evolutionary divergence from other fish species, but with a high degree of identity within the salmonid group. Radioreceptorassay studies have found GHR present in all tissues examined, which is in line with the highly pleiotropic action of GH. Data are currently scarce on the plasma dynamics of GH in salmonids, and further studies on GHR and GHBPs dynamics coupled to assessments of GH clearance rates and pathways are needed. The direct versus indirect nature of GH action remains to be clarified, but GH appears to act both locally at the target tissue level to stimulate the autocrine/paracrine action of IGF-I, as well as on the liver to increase plasma IGF-I levels. In addition, GH interacts with other hormones such as cortisol, thyroid hormones, insulin, and reproductive hormones, generating a wide range of physiological effects. GH may act both peripherally and directly at the level of the central nervous system to modify behavior, probably by altering the dopaminergic activity in the brain.
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| 19. |
- Carney Almroth, Bethanie, 1974, et al.
(författare)
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Oxidative stress and biomarker responses in the Atlantic halibut after long term exposure to elevated CO2 and a range of temperatures
- 2019
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Ingår i: Comparative Biochemistry and Physiology B-Biochemistry & Molecular Biology. - : Elsevier BV. - 1096-4959. ; 238
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Tidskriftsartikel (refereegranskat)abstract
- CO2 emissions from human activities are increasing, resulting in greater rates of change in the oceans, exceeding any other event in geological and historical records over the past 300 million years. Oceans are warming and pH levels are decreasing. Marine organisms will need to respond to multiple stressors and the potential consequences of global change-related effects in fish needs to be investigated. Fish are affected by many biotic and abiotic environmental variables, including temperature and CO2 fluctuations, and it is therefore critical to investigate how these variables may affect physiological and biochemical processes. We investigated the effects of elevated CO2 levels (pH of 8.0, which served as a control, or 7.6, which is predicted for the year 2100) combined with exposure to different temperatures (5, 10, 12, 14, 16, and 18 degrees C) in the Atlantic halibut (Hippoglossus hippoglossus) during a three month experiment. Since regulation of reactive oxygen species (ROS) is crucial for physiological processes the focus was on the antioxidant defense system and we assessed the effects on catalytic activities of antioxidant enzymes (SOD, CAT, GR, GST, GPx). In addition we also analyzed effects on cholinesterase enzymes (AChE and BChE), and CYP1A enzyme activities (EROD). The treatments resulted in oxidative stress, and damage was evident in the form of protein carbonyls which were consistently higher in the elevated CO2 -treated fish at all temperatures. Analyses of antioxidant enzymes did not show the same results, suggesting that the exposure to elevated CO2 increased ROS formation but not defences. The antioxidant defense system was insufficient, and the resulting oxidative damage could impact physiological function of the halibut on a cellular level.
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| 20. |
- Crespo, D., et al.
(författare)
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The initiation of puberty in Atlantic salmon brings about large changes in testicular gene expression that are modulated by the energy status
- 2019
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Ingår i: BMC Genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 20
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundWhen puberty starts before males reach harvest size, animal welfare and sustainability issues occur in Atlantic salmon (Salmo salar) aquaculture. Hallmarks of male puberty are an increased proliferation activity in the testis and elevated androgen production. Examining transcriptional changes in salmon testis during the transition from immature to maturing testes may help understanding the regulation of puberty, potentially leading to procedures to modulate its start. Since differences in body weight influence, via unknown mechanisms, the chances for entering puberty, we used two feed rations to create body weight differences.ResultsMaturing testes were characterized by an elevated proliferation activity of Sertoli cells and of single undifferentiated spermatogonia. Pituitary gene expression data suggest increased Gnrh receptor and gonadotropin gene expression, potentially responsible for the elevated circulating androgen levels in maturing fish. Transcriptional changes in maturing testes included a broad variety of signaling systems (e.g. Tgf, Wnt, insulin/Igf, nuclear receptors), but also, activation of metabolic pathways such as anaerobic metabolism and protection against ROS. Feed restriction lowered the incidence of puberty. In males maturing despite feed restriction, plasma androgen levels were higher than in maturing fish receiving the full ration. A group of 449 genes that were up-regulated in maturing fully fed fish, was up-regulated more prominently in testis from fish maturing under caloric restriction. Moreover, 421 genes were specifically up-regulated in testes from fish maturing under caloric restriction, including carbon metabolism genes, a pathway relevant for nucleotide biosynthesis and for placing epigenetic marks.ConclusionsUndifferentiated spermatogonia and Sertoli cell populations increased at the beginning of puberty, which was associated with the up-regulation of metabolic pathways (e.g. anaerobic and ROS pathways) known from other stem cell systems. The higher androgen levels in males maturing under caloric restriction may be responsible for the stronger up-regulation of a common set of (449) maturation-associated genes, and the specific up-regulation of another set of (421) genes. The latter opened regulatory and/or metabolic options for initiating puberty despite feed restriction. As a means to reduce the incidence of male puberty in salmon, however, caloric restriction seems unsuitable.
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| 21. |
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| 22. |
- Einarsdottir, Ingibjörg, 1951, et al.
(författare)
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Occurrence of ghrelin-producing cells, the ghrelin receptor and Na+,K+-ATPase in tissues of Atlantic halibut
- 2011
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Ingår i: Cell and Tissue Resarch. - 0302-766X. ; 344:3, s. 481-498
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Tidskriftsartikel (refereegranskat)abstract
- Ghrelin is a pituitary growth hormone (GH)-secretagogue that also has metabolic, reproductive, proliferative, immunological and brain functions in mammals. Far less is known about its role in fish. We have therefore performed an immunohistochemical determination of its tissue distribution in the developing Atlantic halibut (Hippoglossus hippoglossus) to gain insights into its potential function. Ghrelin immunoreactivity was detected in first-feeding halibut larvae in the skin, urinary bladder, gastrointestinal (GI) tract and olfactory lobe of the brain. In subsequent stages up to metamorphosis, ghrelin immunoreactivity declined in the skin and became evident in the gills. When the stomach developed, ghrelin immunoreactivity declined throughout the GI tract with the exception of the stomach, which exhibited an intense signal. Immunoreactive ghrelin cells were also present in the olfactory lobe, nerve and epithelium and in occasional cells of the buccal cavity and oesophagus. Ghrelin immunoreactivity had an overlapping distribution with that for Na(+),K(+)-ATPase, colocalisation also being observed in some ionocytes of the gill. The co-expression of ghrelin and the GH-secretagogue receptor in the same tissue indicates that ghrelin can exert both endocrine and paracrine actions in the developing halibut. The presence of immunoreactive ghrelin in several osmoregulatory tissues, the GI tract and sensory tissue provides strong evidence that ghrelin has multiple functions during development and also suggests targets for future investigations.
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| 23. |
- Einarsdottir, Ingibjörg, 1951, et al.
(författare)
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Plasma growth hormone-binding protein levels in Atlantic salmon Salmo salar during smoltification and seawater transfer
- 2014
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Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112. ; 85:4, s. 1279-1296
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Tidskriftsartikel (refereegranskat)abstract
- Specific growth hormone (GH)-binding protein (Ghbp) was purified from Atlantic salmon Salmo salar and rainbow trout Oncorhynchus mykiss plasma with immunoprecipitation and characterized in cross-linking studies using autoradiography and western blots. The size of the Ghbp was estimated to be c. 53 kDa. A radioimmunoassay was established to measure Ghbp in salmonids, using antibodies specific against the extracellular segment of the S. salar growth hormone receptor 1 (grh1; GenBank AY462105). Plasma Ghbp levels were measured in S. salar smolts in fresh water and after transfer to seawater (SW; experiments 1 and 2), and in post-smolts kept at different salinities (0, 12, 22 and 34) for 3 months (experiment 3). A transient increase in plasma Ghbp, which lasted for 1 month or less, was noted in smolts after transfer to SW. Concomitantly, plasma GH and gill Na+-K+-ATPase activity increased during smoltification (in experiment 2). No difference in plasma Ghbp was evident between post-smolts kept at different salinities, although the fish kept at salinity 34 had higher plasma GH than the group kept at salinity 22 and higher hepatic ghr1 expression than post-smolts kept at salinity 12. This suggests that plasma Ghbp regulation may respond to salinity changes in the short term. The lack of correlation between Ghbp, plasma GH and hepatic ghr1 expression in the long-term post-smolt experiment indicates that Ghbp levels may be regulated independently of other components of the endocrine GH system in salmonids.
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| 24. |
- Gong, Ningping, 1979, et al.
(författare)
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Acute anorexigenic action of leptin in rainbow trout is mediated by the hypothalamic Pi3k pathway
- 2016
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Ingår i: Journal of Molecular Endocrinology. - 0952-5041. ; 56:3, s. 227-238
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Tidskriftsartikel (refereegranskat)abstract
- Leptin (Lep) is an anorexigenic hormone and regulates appetite-related neuropeptides in mammals. A number of neuropeptides have also been linked to appetite regulation in 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 amphetamineregulated transcript (Cart) and orexigenic neuropeptide Y. At high dose, Lep stimulates hypothalamic transcription of anorexigenic proopiomelanocortin (Pomc) A1, A2, and B, while coinjection with LY294002 reverses this upregulation. The data suggest that the anorexigenic action of Lep in rainbow trout is mediated through stimulation of the anorexigenic neuropeptides Pomc and Cart. Furthermore, ICV Lep treatment increases phosphor-Akt-immunoreactive cells in the nucleus lateralis tuberis, periventricular zone along infundibulum, and lateral recess surrounded by nucleus anterior tuberis, while LY294002 inhibits this effect. Lep receptor-immunoreactive cells are also predominant in these regions. These results demonstrate that Lep activates the Pi3k-Akt pathway in the lateral tuberal hypothalamus of rainbow trout for acute appetite regulation, indicating the conservation of anorexigenic Lep action in the mediobasal hypothalamus. © 2016 Society for Endocrinology.
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| 25. |
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| 26. |
- Hedén, Ida, 1984, et al.
(författare)
-
The role of environmental salinity on Na+-dependent intestinal amino acid uptake in rainbow trout (Oncorhynchus mykiss)
- 2022
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 12:1
-
Tidskriftsartikel (refereegranskat)abstract
- Na+/K+-ATPases (NKA) in the basolateral membrane of the intestinal enterocytes create a Na+-gradient that drives both ion-coupled fluid uptake and nutrient transport. Being dependent on the same gradient as well as on the environmental salinity, these processes have the potential to affect each other. In salmonids, L-lysine absorption has been shown to be higher in freshwater (FW) than in seawater (SW) acclimated fish. Using electrophysiology (Ussing chamber technique), the aim was to explore if the decrease in L-lysine transport was due to allocation of the Na+-gradient towards ion-driven fluid uptake in SW, at the cost of amino acid transport. Intestinal NKA activity was higher in SW compared to FW fish. Exposure to ouabain, an inhibitor of NKA, decreased L-lysine transport. However, exposure to bumetanide and hydrochlorothiazide, inhibitors of Na+, K+, 2Cl−-co-transporter (NKCC) and Na+, Cl−-co-transporter (NCC) respectively, did not affect the rate of intestinal L-lysine transport. In conclusion, L-lysine transport is Na+-dependent in rainbow trout and the NKA activity and thus the available Na+-gradient increases after SW acclimation. This increased Na+-gradient is most likely directed towards osmoregulation, as amino acid transport is not compromised in SW acclimated fish.
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| 27. |
- Hinchcliffe, James, 1992, et al.
(författare)
-
High protein requirements of juvenile Atlantic wolffish, Anarhichas lupus: Effects of dietary protein levels on growth, health, and welfare
- 2024
-
Ingår i: JOURNAL OF FISH BIOLOGY. - : John Wiley and Sons Inc. - 0022-1112 .- 1095-8649.
-
Tidskriftsartikel (refereegranskat)abstract
- The objective of the present study was to investigate the optimal dietary protein requirement and the effect of varying protein levels on the growth and health of juvenile, wild-caught Atlantic wolffish, Anarhichas lupus, a promising candidate for cold-water aquaculture diversification. Six iso-energetic (ca. 18.3 MJ kg(-1)), fish meal-based experimental diets were formulated with crude protein levels ranging from 35% to 60%, with graded increments of 5% in a 12-week feeding trial in a recirculating aquaculture system (RAS). Weight gain, specific growth rate (SGR), and condition factor (K) were evaluated in response to dietary protein levels. Liver, muscle, and blood parameters were assessed for possible changes in protein and lipid metabolism and welfare. Overall growth was highly variable throughout the experiment on all diets, as expected for a wild population. The feed with highest in protein (60%) inclusion resulted in the highest growth rates, with an average weight gain of 37.4% +/- 33.8% and an SGR of 0.31% +/- 0.2% day-1. This was closely followed by feeds with 55% and 50% protein inclusion with an average weight gain of 22.9% +/- 34.8% and 28.5% +/- 38.3%, respectively, and an SGR of 0.18% +/- 0.3% day(-1 )and 0.22% +/- 0.3% day(-1), respectively. Fish fed the high protein diets generally had increased hepatic lipid deposition (17%-18%) and reduced free fatty acid levels (3.1-6.8 mu mol L-1) in the plasma relative to fish that were fed the lower protein diets (35%-45%). No effects of diet were found on plasma protein levels or muscle protein content. Furthermore, stress parameters such as plasma cortisol and glucose levels were unaffected by diet, as were plasma ghrelin levels. Overall, these results suggest that a high protein inclusion in the diet for Atlantic wolffish is required to sustain growth with a minimum protein level of 50%.
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| 28. |
- Johansson, Viktoria, 1972, et al.
(författare)
-
Peripherally administered growth hormone increases brain dopaminergic activity and swimming in rainbow trout
- 2004
-
Ingår i: Hormones and Behavior. - : Elsevier BV. - 0018-506X. ; 46:4, s. 436-443
-
Tidskriftsartikel (refereegranskat)abstract
- There is increasing evidence that growth hormone (GH) has important behavioral effects in fish, but the underlying mechanisms are not well understood. To investigate if peripherally administered GH influences the monoaminergic activity of the brain, and how this is correlated to behavior, juvenile rainbow trout were implanted intraperitoneally with ovine GH. Fish were either kept isolated or in groups of five. The physical activity and food intake of the isolated fish were observed after 1 and 7 days, when brains were also sampled. The content of serotonin, dopamine, and noradrenaline and their metabolites in hypothalamus, telencephalon, optic tectum, and brain stem was then analyzed. For fish kept isolated for 7 days following implant, GH increased swimming activity and the levels of the dopamine metabolite 3, 4-hydroxy-phenylacetic acid (DOPAC) were higher in all brain parts examined. In the optic tectum, the levels of the dopamine metabolite homovanillic acid (HVA) were lowered by the GH treatment. One-day GH implant did not affect behavior or monoamine levels of isolated fish. In the fish kept in groups, a 7-day GH implant increased the hypothalamic levels of DOPAC, but not in the other brain parts examined, which may indicate an effect on the brain dopaminergic system from social interactions. It can be concluded that peripherally administered GH may function as a neuromodulator, affecting the dopaminergic activity of the rainbow trout brain, and this is associated with increased swimming activity. (C) 2004 Elsevier Inc. All rights reserved.
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| 29. |
- Johnsen, Chris Andre, et al.
(författare)
-
Seasonal changes in muscle structure and flesh quality of 0+ and 1+ Atlantic salmon (Salmo salara L.):impact of feeding regime and possible roles of ghrelin
- 2013
-
Ingår i: Aquaculture Nutrition. - : Hindawi Limited. - 1353-5773 .- 1365-2095. ; 19:1, s. 15-34
-
Tidskriftsartikel (refereegranskat)abstract
- Growth performance, muscle cellularity, flesh quality, and plasma ghrelin were investigated in 0+ and 1+ farmed Atlantic salmon (Salmo salar L.) from 40 g to 4.3 kg. Reduced meal frequency was introduced in both smolt groups from ~1.5 kg; one meal per second day (<5 °C) to one daily meal (>5 °C), while control groups were fed one to three daily meals. Results show that 0+ salmon had higher final fibre number and density, pigment content, red colour intensity, firmer flesh, and lower fillet fat content than 1+ salmon at 4.3 kg, affected by season and smolt type. Muscle fibre recruitment was an important determinant of fillet firmness and colour, possibly influenced by the prenatal temperature regime. Fish fed reduced meal frequency showed temporal reduced feeding ration, but growth performance was not compromised in any smolt groups at harvest. However, fillet fat, gaping, and colour decreased by less frequent feeding, with permanent effects in 1+ salmon for gaping and fat. Reduced meal frequency is therefore considered to be a promising tool for managing important flesh quality attributes in salmon without compromising growth performance. It is also suggested that ghrelin stimulates short-term appetite, and perhaps also in the longer term.
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| 30. |
- Jönsson, Elisabeth, 1968, et al.
(författare)
-
Circulating levels of cholecystokinin and gastrin-releasing peptide in rainbow trout fed different diets.
- 2006
-
Ingår i: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480. ; 148:2, s. 187-194
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 31. |
- Jönsson, Elisabeth, 1968, et al.
(författare)
-
Endocrine systems of the gut
- 2011
-
Ingår i: Encyclopedia of Fish Physiology: From gene to environment. (A.P. Farrell ed). Elsevier. - : Academic Press. - 9780123745453 ; , s. 1341-1347
-
Bokkapitel (refereegranskat)abstract
- The gut endocrine system comprises dispersed enteroendocrine cells in its epithelium. These cells produce many different hormones, with important roles in control of gastrointestinal functions such as appetite and food processing. Many hormones like serotonin are present both in gut nerves and/or endocrine cells, and others, like glucagon-like peptide-1, are secreted both from pancreas and intestinal mucosa. The effects range from local paracrine (or neurocrine) to broad general effects. Histamine and somatostatin produced by stomach mucosa locally stimulate the stomach to release gastric acid. Cholecystokinin produced by intestinal cells has broader effects, inducing gallbladder contraction and inhibiting appetite. Ghrelin has even more widespread effects, being a potent growth hormone secretagog and appetite regulator, besides having other functions. Leptin was only recently discovered in fish gut.
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| 32. |
- Jönsson, Elisabeth, 1968, et al.
(författare)
-
Ghrelin decreases food intake in juvenile rainbow trout (Oncorhynchus mykiss) through the central anorexigenic corticotropin-releasing factor system
- 2010
-
Ingår i: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480. ; 166:166, s. 39-46
-
Tidskriftsartikel (refereegranskat)abstract
- 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 α-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 1 h 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.
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| 33. |
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| 34. |
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| 35. |
- Jönsson, Elisabeth, 1968, et al.
(författare)
-
Plasma ghrelin levels in rainbow trout in response to fasting, feeding and food composition, and effects of ghrelin on voluntary food intake
- 2007
-
Ingår i: Comparative Biochemistry and Physiology - Part A: Molecular & Integrative Physiology. - : Elsevier BV. - 1095-6433. ; 147:4, s. 1116-1124
-
Tidskriftsartikel (refereegranskat)abstract
- Ghrelin, a peptide hormone which stimulates growth hormone (GH) release, appetite and adiposity in mammals, was recently identified in fish. In this study, the roles of ghrelin in regulating food intake and the growth hormone (GH)–insulin-like growth factor I (IGF-I) system of rainbow trout (Oncorhynchus mykiss) were investigated in three experiments: 1) Pre- and postprandial plasma levels of ghrelin were measured in relation to dietary composition and food intake through dietary inclusion of radio-dense lead-glass beads, 2) the effect of a single intraperitoneal (i.p.) injection with rainbow trout ghrelin on short-term voluntary food intake was examined and 3) the effect of one to three weeks fasting on circulating ghrelin levels and the correlation with plasma GH and IGF-I levels, growth and lipid content in the liver and muscle was studied. There was no postprandial change in plasma ghrelin levels. Fish fed a normal-protein/high-lipid (31.4%) diet tended to have higher plasma ghrelin levels than those fed a high-protein/low-lipid (14.1%) diet. Plasma ghrelin levels decreased during fasting and correlated positively with specific growth rates, condition factor, liver and muscle lipid content, and negatively with plasma GH and IGF-I levels. An i.p. ghrelin injection did not affect food intake during 12-hours post-injection. It is concluded that ghrelin release in rainbow trout may be influenced by long-term energy status, and possibly by diet composition. Further, in rainbow trout, ghrelin seems to be linked to growth and metabolism, but does not seem to stimulate short-term appetite through a peripheral action.
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| 36. |
|
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| 37. |
- Jönsson, Elisabeth, 1968
(författare)
-
The role of ghrelin in energy balance regulation in fish
- 2013
-
Ingår i: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480. ; 187, s. 79-85
-
Tidskriftsartikel (refereegranskat)abstract
- Knowledge about the endocrine regulation of energy balance in fish is of interest for basic as well as aquaculture research. Ghrelin is a peptide hormone that was first identified in fish 10 years ago and has important roles in the control of food intake and metabolism. Both ghrelin and its receptor, the growth hormone secretagogue receptor (GHS-R), have been found in numerous fish species. Their tissue distributions support the idea that ghrelin has an integrative role in the regulation of energy balance at both the central nervous system level and systemic level. In tilapia and goldfish, ghrelin treatment appears to increase food intake and to stimulate lipogenesis and tissue fat deposition to promote a more positive energy status. In rainbow trout, on the other hand, ghrelin decreases food intake. Goldfish and rainbow trout are the fish species in which the mode of action of ghrelin on food intake has been most thoroughly investigated. The results from these studies indicate that ghrelin alters food intake by acting on well-known appetite signals, such as CRH, NPY and orexin, in the hypothalamus in a species-specific manner. In goldfish, sensory fibres of the vagus nerve convey the signal from gut-derived ghrelin to modulate appetite. The data also indicate that ghrelin may modulate foraging/swimming activity and the perception of food in fish. Results related to the effects of energy status, temperature, and stressors on plasma ghrelin/tissue ghrelin mRNA levels are occasionally inconsistent between short- and long-term studies, between the protein and mRNA, and between species. Recent data also imply a role of ghrelin in carbohydrate metabolism. More functional studies are required to understand the role of ghrelin and its mechanisms of action in the regulation of energy balance among fish.
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| 38. |
- Khansari, Ali Reza, 1980, et al.
(författare)
-
Sea water acclimation of rainbow trout (Oncorhynchus mykiss) modulates the mucosal transcript immune response induced by Vibrio anguillarum and Aeromonas salmonicida vaccine, and prevents further transcription of stress-immune genes in response to acute stress
- 2024
-
Ingår i: FISH & SHELLFISH IMMUNOLOGY. - 1050-4648 .- 1095-9947. ; 152
-
Tidskriftsartikel (refereegranskat)abstract
- Mucosal tissues appear to be more important in fish than in mammals due to living in a microbial-rich aquatic milieu, yet the complex interaction between the immune and the neuroendocrine system in these tissues remains elusive. The aim of this work was to investigate the mucosal immune response in immunized rainbow trout vaccinated with Alpha ject vaccine (bivalent), kept in fresh water (FW) or transferred to seawater (SW), and to evaluate their response to acute stress (chasing). Acute stress resulted in higher levels of plasma cortisol (Sham + Stress and Vaccine + Stress). A similar response was observed in skin mucus, but it was lower in Vaccine + Stress compared with stressed fish. With a few exceptions, minimal alterations were detected in the transcriptomic profile of stress-immune gene in the skin of vaccinated and stressed fish in both FW and SW. In the gills, the stress elicited activation of key stress-immune components (gr1, mr, (1-ar, hsp70, c3, lysozyme, alpha-enolase, nadph oxidase, il1(1, il6, tnf alpha, il10 and tgf(11) in FW, but fewer immune changes were induced by the vaccine (nadph oxidase, il6, tnf alpha, il10 and igt) in both SW and FW. In the intestine, an array of immune genes was activated by the vaccine particularly those related with B cells (igm, igt) and T cells (cd8 alpha) in FW with no stimulation observed in SW. Therefore, our survey on the transcriptomic mucosal response demonstrates that the immune protection conferred by the vaccine to the intestine is modulated in SW. Overall, our results showed: i) plasma and skin mucus cortisol showed no additional stress effect induced by prolonged SW acclimation, ii) the stress and immune response were different among mucosal tissues which indicates a tissue-specific response to specific antigens/stressor. Further, the results suggest that the systemic immune organs may be more implicated in infectious events in SW (as few changes were observed in the mucosal barriers of immunized fish in SW) than in FW.
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| 39. |
- Kullgren, Andreas, 1977, et al.
(författare)
-
A metabolomics approach to elucidate effects of food deprivation in juvenile rainbow trout (Oncorhynchus mykiss)
- 2010
-
Ingår i: American Journal of Physiology-Regulatory Integrative and Comparative Physiology. - : American Physiological Society. - 0363-6119 .- 1522-1490. ; 299:6
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to evaluate whether NMR-based metabolomics is a suitable method to generate an integrated view on metabolic processes during food deprivation in salmonid fish. Juvenile rainbow trout (Oncorhynchus mykiss) weighing 43-115 g were either fed ad libitum or deprived of food for 28 days at 10 degrees C to investigate catabolic effects on energy reserves and metabolite patterns. The NMR analysis of plasma, liver, and muscle extracts revealed significant fasting-induced changes in the metabolome. Altered plasma lipoprotein levels and tissue-specific patterns of fatty acid mobilization were the most prominent responses, emphasizing the role of lipids as the primary energy source during fasting. In plasma, very-low-density lipoprotein levels increased in food-deprived fish compared with fed fish, whereas levels of high-density lipoprotein decreased. Signs of muscle protein catabolism were also observed as changes in the alanine dynamics. The results further suggest that mechanisms to preserve liver glycogen are present in the food-deprived fish. This study thus demonstrates the utility of NMR-based metabolomics of tissue extracts and plasma to describe the integrated metabolic status of fish.
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| 40. |
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| 41. |
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| 42. |
- Perello-Amoros, M., et al.
(författare)
-
Ghrelin and Its Receptors in Gilthead Sea Bream: Nutritional Regulation
- 2018
-
Ingår i: Frontiers in Endocrinology. - : Frontiers Media SA. - 1664-2392. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Ghrelin is involved in the regulation of growth in vertebrates through controlling different functions, such as feed intake, metabolism, intestinal activity or growth hormone (Gh) secretion. The aim of this work was to identify the sequences of preproghrelin and Ghrelin receptors (ghsrs), and to study their responses to different nutritional conditions in gilthead sea bream {Sparus aurata) juveniles. The structure and phylogeny of S. aurata preproghrelin was analyzed, and a tissue screening was performed. The effects of 21 days of fasting and 2, 5, 24h, and 7 days of refeeding on plasma levels of Ghrelin, Gh and Igf-1, and the gene expression of preproghrelin, ghsrs and members of the Gh/Igf-1 system were determined in key tissues. preproghrelin and the receptors are well conserved, being expressed mainly in stomach, and in the pituitary and brain, respectively. Twenty-one days of fasting resulted in a decrease in growth while Ghrelin plasma levels were elevated to decrease at 5h post-prandial when pituitary ghsrs expression was minimum. Gh in plasma increased during fasting and slowly felt upon refeeding, while plasma Igf-1 showed an inverse profile. Pituitary gh expression augmented during fasting reaching maximum levels at 1 day post-feeding while liver igf-1 expression and that of its splice variants decreased to lowest levels. Liver Gh receptors expression was down-regulated during fasting and recovered after refeeding. This study demonstrates the important role of Ghrelin during fasting, its acute down-regulation in the post-prandial stage and its interaction with pituitary Ghsrs and Gh/Igf-1 axis.
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| 43. |
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| 44. |
- Ronnestad, I., et al.
(författare)
-
Appetite-Controlling Endocrine Systems in Teleosts
- 2017
-
Ingår i: Frontiers in Endocrinology. - : Frontiers Media SA. - 1664-2392. ; 8
-
Tidskriftsartikel (refereegranskat)abstract
- Mammalian studies have shaped our understanding of the endocrine control of appetite and body weight in vertebrates and provided the basic vertebrate model that involves central (brain) and peripheral signaling pathways as well as environmental cues. The hypothalamus has a crucial function in the control of food intake, but other parts of the brain are also involved. The description of a range of key neuropeptides and hormones as well as more details of their specific roles in appetite control continues to be in progress. Endocrine signals are based on hormones that can be divided into two groups: those that induce (orexigenic), and those that inhibit (anorexigenic) appetite and food consumption. Peripheral signals originate in the gastrointestinal tract, liver, adipose tissue, and other tissues and reach the hypothalamus through both endocrine and neuroendocrine actions. While many mammalian-like endocrine appetite-controlling networks and mechanisms have been described for some key model teleosts, mainly zebrafish and goldfish, very little knowledge exists on these systems in fishes as a group. Fishes represent over 30,000 species, and there is a large variability in their ecological niches and habitats as well as life history adaptations, transitions between life stages and feeding behaviors. In the context of food intake and appetite control, common adaptations to extended periods of starvation or periods of abundant food availability are of particular interest. This review summarizes the recent findings on endocrine appetite-controlling systems in fish, highlights their impact on growth and survival, and discusses the perspectives in this research field to shed light on the intriguing adaptations that exist in fish and their underlying mechanisms.
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| 45. |
- Salmeron, C., et al.
(författare)
-
Effects of nutritional status on plasma leptin levels and in vitro regulation of adipocyte leptin expression and secretion in rainbow trout
- 2015
-
Ingår i: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480. ; 210, s. 114-123
-
Tidskriftsartikel (refereegranskat)abstract
- As leptin has a key role on appetite, knowledge about leptin regulation is important in order to understand the control of energy balance. We aimed to explore the modulatory effects of adiposity on plasma leptin levels in vivo and the role of potential regulators on leptin expression and secretion in rainbow trout adipocytes in vitro. Fish were fed a regular diet twice daily ad libitum or a high-energy diet once daily at two ration levels; satiation (SA group) or restricted (RE group) to 25% of satiation, for 8 weeks. RE fish had significantly reduced growth (p < 0.001) and adipose tissue weight (p < 0.001), and higher plasma leptin levels (p = 0.022) compared with SA fish. Moreover, plasma leptin levels negatively correlated with mesenteric fat index (p = 0.009). Adipocytes isolated from the different fish were treated with insulin, ghrelin, leucine, eicosapentaenoic acid or left untreated (control). In adipocytes from fish fed regular diet, insulin and ghrelin increased leptin secretion dose-dependently (p = 0.002; p = 0.033, respectively). Leptin secretion in control adipocytes was significantly higher in RE than in SA fish (p = 0.022) in agreement with the in vivo findings, indicating that adipose tissue may contribute to the circulating leptin levels. No treatment effects were observed in adipocytes from the high-energy diet groups, neither in leptin expression nor secretion, except that leptin secretion was significantly reduced by leucine in RE fish adipocytes (p = 0.025). Overall, these data show that the regulation of leptin in rainbow trout adipocytes by hormones and nutrients seems to be on secretion, rather than at the transcriptional level. (C) 2014 Elsevier Inc. All rights reserved.
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| 46. |
- Salmeron, C., et al.
(författare)
-
Roles of leptin and ghrelin in adipogenesis and lipid metabolism of rainbow trout adipocytes in vitro
- 2015
-
Ingår i: Comparative Biochemistry and Physiology a-Molecular & Integrative Physiology. - : Elsevier BV. - 1095-6433. ; 188, s. 40-48
-
Tidskriftsartikel (refereegranskat)abstract
- Leptin and ghrelin are important regulators of energy homeostasis in mammals, whereas their physiological-roles in fish have not been fully elucidated. In the present study, the effects of leptin and ghrelin on adipogenesis, lipolysis and on expression of lipid metabolism-related genes were examined in rainbow trout adipocytes in vitro. Leptin expression and release increased from preadipocytes to mature adipocytes in culture, but did not affect the process of adipogenesis. While ghrelin and its receptor were identified in cultured differentiated adipocytes, ghrelin did not influence either preadipocyte proliferation or differentiation, indicating that it may have other adipose-related roles. Leptin and ghrelin increased lipolysis in mature freshly isolated adipocytes, but mRNA expression of lipolysis markers was not significantly modified. Leptin significantly suppressed the fatty acid transporter-1 expression, suggesting a decrease in fatty acid uptake and storage, but did not affect expression of any of the lipogenesis or beta-oxidation genes studied. Ghrelin significantly increased the mRNA levels of lipoprotein lipase, fatty acid synthase and peroxisome proliferator-activated receptor-beta, and thus appears to stimulate synthesis of triglycerides as well as their mobilization. Overall, the study indicates that ghrelin, but not leptin seems to be an enhancer of lipid turn-over in adipose tissue of rainbow trout, and this regulation may at least partly be mediated through autocrine/paracrine mechanisms. The mode of action of both hormones needs to be further explored to better understand their roles in regulating adiposity in fish. (C) 2015 Elsevier Inc. All rights reserved.
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| 47. |
- Sundh, Henrik, 1976, et al.
(författare)
-
NUTRIENT ABSORPTION IN THE ATLANTIC SALMON (SALMO SALAR L.) INTESTINE IS AFFECTED BY ENVIRONMENTAL SALINITY
- 2014
-
Ingår i: ICBF 2014, Edinburgh.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Na+/K+-ATPases (NKA) located in the basolateral membrane of the intestinal absorptive cells (enterocytes) are the main driving force for both ion-coupled intestinal fluid transport and nutrient absorption in Atlantic salmon in seawater. It is hypothesized that a decreased need for osmoregulation in brackish water may be beneficial for the nutrient uptake and thereby the growth of the fish. Atlantic salmon post-smolts were acclimated to freshwater (FW), 12, 22 and 34 ppt seawater (SW) for several months. The intestinal nutrient transport (L-lysine and D-glucose) was measured in Ussing chambers and separate fish were used for intestinal mRNA expression of selected ion and nutrient transporters. No differences were found in mRNA levels of the NKA-α1c, NKCC2 co-transporter or SGLT-1 in relation to salinity, whereas the specific high-affinity low capacity Na+-coupled nutrient transport was significantly higher in FW and 22 ppt as compared to the 34 ppt group. The results suggest an allocation of the electrochemical gradient towards ion driven fluid transport in full strength SW.
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| 48. |
- Tinoco, Ana B, et al.
(författare)
-
Ghrelin increases food intake, swimming activity and growth in juvenile brown trout (Salmo trutta)
- 2014
-
Ingår i: Physiology and Behavior. - : Elsevier BV. - 0031-9384 .- 1873-507X. ; 124, s. 15-22
-
Tidskriftsartikel (refereegranskat)abstract
- Several key functions of ghrelin are well conserved through vertebrate phylogeny. However, some of ghrelin's effects are contradictory and among teleosts only a limited number of species have been used in functional studies on food intake and foraging-related behaviors. Here we investigated the long-term effects of ghrelin on food intake, growth, swimming activity and aggressive contest behavior in one year old wild brown trout (Salmo trutta) using intraperitoneal implants. Food intake and swimming activity were individually recorded starting from day 1, and aggressive behavior was tested at day 11, after ghrelin implantation. Body weight and growth rate were measured from the beginning to the end of the experiment. Triglycerides and lipase activity in muscle and liver; monoaminergic activity in the telencephalon and brainstem; and neuropeptide Y (NPY) mRNA levels in the hypothalamus were analyzed. Ghrelin treatment was found to increase food intake and growth without modifying lipid deposition or lipid metabolism in liver and muscle. Ghrelin treatment led to an increased foraging activity and a trend towards a higher swimming activity. Moreover, ghrelin-treated fish showed a tendency to initiate more conflicts, but this motivation was not reflected in a higher ability to win the conflicts. No changes were observed in monoaminergic activity and NPY mRNA levels in the brain. Ghrelin is therefore suggested to act as an orexigenic hormone regulating behavior in juvenile wild brown trout. These actions are accompanied with an increased growth without the alteration of liver and muscle lipid metabolism and they do not seem to be mediated by changes in brain monoaminergic activity or hypothalamic expression of NPY.
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| 49. |
- Tinoco, Ana Belén, et al.
(författare)
-
Regulación de la ingesta, el crecimiento y el comportamiento por ghrelina en ejemplares salvajes de trucha marrón (Salmo trutta)
- 2011
-
Ingår i: Libro de actas: XIII Congreso Nacional Acuicultura, Barcelona 2011.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Studies in teleosts reveal that several key functions of ghrelin have been conserved during vertebrate evolution. However, results in rainbow trout (Oncorhynchus mykiss) showed different effects of this hormone. Our aim was to clarify if these results are representative for salmonids, or reflect domestication effects, since rainbow trout has been artificially selected for rapid growth. Thus, the long-term effect of ghrelin implants in wild brown trout (S. trutta) parr was studied. Ghrelin significantly increased food intake and specific growth rate. Moreover, an increase tendency was observed in swim activity and aggressive behavior in ghrelin treated fish. Therefore, ghrelin seems to have the same functions in wild salmonids as in other fish, and the altered ghrelin actions in rainbow trout are likely due to domestication effects, although species-specific effects cannot be ruled out. Additional studies are necessary to clarify if ghrelin affect swim activity and aggressive behavior in salmonids.
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- Warwas, Niklas, et al.
(författare)
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Fish processing side streams are promising ingredients in diets for rainbow trout (Oncorhynchus mykiss) - Effects on growth physiology, appetite, and intestinal health
- 2023
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Ingår i: Journal of Fish Biology. - : John Wiley and Sons Inc. - 0022-1112 .- 1095-8649.
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Tidskriftsartikel (refereegranskat)abstract
- Due to the growth of aquaculture and the finite supply of fishmeal and oil, alternative marine protein and lipid sources are highly sought after. Particularly promising is the use of side streams from the fish processing industry, allowing for the recovery and retention of otherwise lost nutrients in the food production chain. The aim of the present study was to evaluate the potential of three fish processing side streams as fish feed ingredients. The side streams originated from different stages of the production chain, were used without further processing, and included sprat trimmings (heads, frames, viscera), marinated herring (fillets) and mackerel in tomato sauce (fillets and sauce). The three side streams contained moderate levels of protein (28-32% dry matter) and high levels of lipid (34-43%). The sprat trimmings included ca. 29% ash and 1.5% phosphorous which may add value due to the high level of essential minerals but needs to be considered in feed formulations. Three diets were formulated to include 50% of each side stream replacing all fishmeal and ca. 80% of the fish oil of the control diet, which contained 35% fishmeal and 10% fish oil. The diets were evaluated in a 12-week feeding trial using rainbow trout (Oncorhynchus mykiss). Fish fed the sprat diet displayed the highest feed intake and growth, and showed no negative effects on the intestinal health. The mackerel side stream displayed a good digestibility but resulted in lower growth rates compared to the sprat trimmings. Fish fed the herring diet, displayed the lowest performance regarding growth, feed intake and digestibility. They further exhibited a reduction in nutrient uptake in both proximal and distal intestine, likely contributing to the observed lower digestibility and growth, and a reduction in plasma ghrelin levels. As part of a circular approach to increase marine lipid and protein production for fish feed, the tested sprat and mackerel side streams are promising raw materials however additional studies using more commercial-like feed formulations are encouraged.
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