SwePub - search: WFRF:(Sundell Kristina 1959)

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1.	Lind, Ulrika, et al. (author) Molecular Characterization of the alpha-Subunit of Na+/K+ ATPase from the Euryhaline Barnacle Balanus improvisus Reveals Multiple Genes and Differential Expression of Alternative Splice Variants 2013 In: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 8:10 Journal article (peer-reviewed)abstract The euryhaline bay barnacle Balanus improvisus has one of the broadest salinity tolerances of any barnacle species. It is able to complete its life cycle in salinities close to freshwater (3 PSU) up to fully marine conditions (35 PSU) and is regarded as one of few truly brackish-water species. Na+/K+ ATPase (NAK) has been shown to be important for osmoregulation when marine organisms are challenged by changing salinities, and we therefore cloned and examined the expression of different NAKs from B. improvisus. We found two main gene variants, NAK1 and NAK2, which were approximately 70% identical at the protein level. The NAK1 mRNA existed in a long and short variant with the encoded proteins differing only by 27 N-terminal amino acids. This N-terminal stretch was coded for by a separate exon, and the two variants of NAK1 mRNAs appeared to be created by alternative splicing. We furthermore showed that the two NAK1 isoforms were differentially expressed in different life stages and in various tissues of adult barnacle, i.e the long isoform was predominant in cyprids and in adult cirri. In barnacle cyprid larvae that were exposed to a combination of different salinities and pCO(2) levels, the expression of the long NAK1 mRNA increased relative to the short in low salinities. We suggest that the alternatively spliced long variant of the Nak1 protein might be of importance for osmoregulation in B. improvisus in low salinity conditions.
2.	Abro, Rani, et al. (author) Evaluation of chitinolytic activities and membrane integrity in gut tissues of Arctic charr (Salvelinus alpinus) fed fish meal and zygomycete biomass. 2014 In: Comparative Biochemistry and Physiology - Part B: Biochemistry & Molecular Biology. - : Elsevier BV. - 1096-4959 .- 1879-1107. ; 175, s. 1-8 Journal article (peer-reviewed)abstract Chitinolytic activity, nutrient uptake and intestinal barrier functions were investigated in gut tissues of Arctic charr (Salvelinus alpinus) fed iso-nitrogenous diets based on fish meal, with or without inclusion of zygomycetes (Rhizopus oryzae). We found that gut tissue of Arctic charr had significant chitinase activity, of both endo- and exo-chitinase iso-forms. Moreover, the distribution pattern along the GI tract of Arctic charr differed between endo-chitinase and exo-chitinase. The endo-chitinase activity in stomach tissue and in the distal intestine was several hundred-fold higher than the exo-chitinase activity in stomach tissue. The greatest exo-chitinase activity was found in the distal intestine. The zygomycete-based diet resulted in higher chitinolytic activity in gut tissue compared to the fish meal-based diet. Disturbed intestinal integrity and increased uptake rate of the amino acid lysine were observed in the distal, but not proximal, intestine of fish fed the zygomycete-based feed.
3.	Albertsson, Eva, 1979, et al. (author) Marin fiskodling på den svenska västkusten: Biologiska förutsättningar : Rapport nummer 1 från Vattenbrukscentrum Väst, Göteborgs universitet 2013 Reports (other academic/artistic)abstract I den av regeringen beställda utredningen ”Det växande Vattenbrukslandet” föreslås att ”Göteborgs universitet (GU) tillförs resurser för att fortsätta att utveckla vattenbruksrelaterad forskning när det gäller musslor, ostron och marina fiskarter”. Därför tog under 2011 företrädare inom den odlingsrelaterade fiskforskningen vid Gö- teborgs universitet initiativet till denna studie om förutsättningarna för marin fiskodling. Studien har syftet att utreda de odlingsbiologiska förutsättningarna för etablering av vattenbruk av marina fiskarter på den svenska västkusten. Målet är att den ska kunna användas som kunskapsunderlag för en framtida handlingsplan för fiskodling på västkusten, och främja kunskapsutbytet mellan den fiskodlingsrelaterade forskningen, beslutsfat- tande organ och privata entreprenörer för att utveckla konkurrenskraftiga innovationer inom vattenbruket. En central fråga för sammanhanget är vilka fiskarter det finns potential för att odla på den svenska västkusten. Vattenbruket måste vara ekonomiskt bärkraftigt och en urvalsmodell baserad på svenska marina fiskarters kg- pris i förhållande till en minsta tänkbara produktionskostnad användes därför i denna studie. Vidare bedöm- des arterna utifrån kunskapsläge och odlingspotential. Arterna hälleflundra, tunga, piggvar, havskatt (vanlig och fläckig) samt lyrtorsk och torsk bedömdes att vara ”kandidatarter” för framtida odling i Sverige. För dessa arter gjordes omfattande studier för att vidare utreda behov och möjligheter. Det gjordes även en analys av de abiotiska faktorerna (vattentemperatur, syrgas- och salthalt) på den svenska västkusten. I en sista del av studien kombinerades kunskapen om kandidatarternas biologiska förutsättningar med västkustens abiotiska faktorer. De abiotiska förhållandena på den svenska västkusten är inte odlingsbiologiskt optimala för traditionell nät- kasseodling för någon av de framtagna kandidatarterna, då för höga sommartemperaturer skapar problem för kallvattensarterna medan varmvattensarterna hämmas av de låga vintertemperaturerna. En av de huvudsak- liga slutsatserna i denna rapport är därför att året-runt-bedriven fiskodling i öppna system, såsom i kustnära nätkassar, knappast är praktiskt genomförbart på den svenska västkusten för de arter som i denna studie i övrigt ansågs ha hög odlingspotential. För etablering av framgångsrika odlingssystem behövs speciella tekniska lösningar, som möjliggör reglering av abiotiska faktorer såsom syrgashalter och temperatur. För att Sverige skall kunna bli ett växande vattenbruksland krävs samordnade insatser mellan forskare från flera discipliner, privata aktörer och andra intressenter. Dessutom krävs satsningar på forskning och utredning av de mera tekniskt avancerade odlingssystem som den svenska västkusten kommer behöva. Med tanke på miljöbelastningsproblematiken kring öppna havsbaserade system för fiskodling samt de abiotiska faktorerna längs västkusten som inte är optimala för någon av kandidatarterna i utredningen, så är slutsatsen att man bör undersöka, alternativa odlingssystem till traditionella öppna nätkassar för fiskodling, där man kan kontrollera faktorer som temperatur, salthalt och syrenivåer och minimera utsläppen. Nästa steg som föreslås är att göra en teknisk/ekonomisk utredning kring hållbara havs- eller landbaserade system för marin fiskodling. Utred- ningen bör innehålla fall-studier för en eller två fiskarter och ett kräftdjur och inkludera en myndighetspröv- ning för de framtagna koncepten. Ytterligare en förutsättning för att vattenbruket skall kunna utvecklas är satsningar på nödvändig infrastruktur, som ett marint kläckeri för forskning och utvecklingsarbete.
4.	Björnsson, Björn Thrandur, 1952, et al. (author) Fiskars odlingsbiologi- svenska framtidsperspektiv 2013 In: Formas fokuserar. ; 21, s. 257-269 Journal article (other academic/artistic)
5.	Einarsdottir, Ingibjörg, 1951, et al. (author) Plasma growth hormone-binding protein levels in Atlantic salmon Salmo salar during smoltification and seawater transfer 2014 In: Journal of Fish Biology. - : Wiley. - 0022-1112. ; 85:4, s. 1279-1296 Journal article (peer-reviewed)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.
6.	Gadan, K, et al. (author) Slow release cortisol implants result in impaired innate immune responses and higher infection prevalence following experimental challenge with infectious pancreatic necrosis virus in Atlantic salmon (Salmo salar) parr. 2012 In: Fish & shellfish immunology. - : Elsevier BV. - 1095-9947 .- 1050-4648. ; 32:5, s. 637-44 Journal article (peer-reviewed)abstract Stress can affect the immune system and increase susceptibility to various diseases but knowledge of the underlying mechanisms is scarce. There is a complex interaction between the immune system and the endocrine system of vertebrates. In fish, cortisol is a key hormone regulating stress response and recent studies have also suggested that this hormone can affect the immune system, where cortisol is mainly regarded as an immunosuppressive factor. The aim of the present study was to examine the impact of chronically elevated levels of cortisol on the immune response and susceptibility to experimental infection with infectious pancreatic necrosis virus (IPNV). Further, the effect of IPNV challenge on circulating levels of cortisol was investigated. Atlantic salmon parr were implanted intraperitoneally with sustained-release implants of bovine of cortisol (50 μg cortisol g(-1) body weight in an implant based on vegetable lipids). Vehicle implants were used as control (sham-injected). At 45 days after implantation (DAI), fish were challenged with a low virulent isolate of IPNV (by immersion). Samples of plasma, liver and head kidney was taken from fish before and 24 h, 48 h, 7 days week and 21 days post infection (DPI). Cortisol level in plasma was measured using radioimmunoassay and gene expression in liver and head kidney was analyzed with real-time PCR (RT-PCR). Infection prevalence in infected fish was assessed by virus culture and RT-PCR of head kidney samples. Cortisol implantation compared with sham-implanted fish had increased levels of plasma cortisol at 45 DAI. The relative expression of Interferon alpha-1 (IFNα-1), Myxo virus-1 Mx, Heat-shock protein 70 (HSP70), Serum amyloid A (SAA), Glucocorticoid receptor (GR) and Heat-shock protein 90 (HSP90) tends to be down-regulated by cortisol implantation. There was a higher prevalence of fish with detectable levels of IPNV, as measured by cell culture and RT-PCR, in the cortisol-implanted group challenged with IPNV (0 = 0.0305) relative to the group that received a sham implantation. Further, cortisol seems to delay the induction of the antiviral IFNα-1 pathway and Mx mRNA expression. This study shows that elevated plasma cortisol level leads to an impaired innate immune response, and higher virus (IPNV) prevalence in Atlantic salmon parr.
7.	Gräns, Albin, 1979, et al. (author) Aerobic scope fails to explain the detrimental effects on growth resulting from warming and elevated CO2 in Atlantic halibut 2014 In: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 217:5, s. 711-717 Journal article (peer-reviewed)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.
8.	Jutfelt, Fredrik, 1975, et al. (author) Response to ‘How and how not to investigate the oxygen and capacity limitation of thermal tolerance (OCLTT) and aerobic scope – remarks on the article by Gräns et al.’ 2014 In: Journal of Experimental Biology. - 1477-9145 .- 0022-0949. ; 217, s. 4433-4435 Journal article (other academic/artistic)
9.	Kullgren, Andreas, 1977, et al. (author) The impact of temperature on the metabolome and endocrine metabolic signals in Atlantic salmon (Salmo salar) 2013 In: Comparative Biochemistry and Physiology A. - : Elsevier BV. - 1095-6433 .- 1531-4332. ; 164:1, s. 44-53 Journal article (peer-reviewed)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.
10.	Kvamme, Bjørn Olav, et al. (author) Modulation of innate immune responses in Atlantic salmon by chronic hypoxia-induced stress. 2013 In: Fish & shellfish immunology. - : Elsevier BV. - 1095-9947 .- 1050-4648. ; 34:1, s. 55-65 Journal article (peer-reviewed)abstract Atlantic salmon post-smolts were exposed to either chronic hypoxic (Hy) or normal oxygen (No) conditions in seawater tanks for 58 days, mimicking conditions typical of sea cages for farmed salmon at some periods of the year. By day 29 head kidney macrophages were isolated and subjected to invitro poly I:C stimulation to simulate viral infection, and samples were collected over 48h. By day 58 fish were subjected to invivo stimulation using poly I:C or a Vibrio water-based vaccine to simulate viral or bacterial infection, respectively. The fish were monitored for stress responses and expression of several pro-inflammatory genes in head kidney and intestinal tissue up to five days post-injection. Stress load was monitored by plasma cortisol estimation at days 29 and 58, and on days 1, 2, 3 and 5 post-injection in the invivo trial. Hy exposure resulted in elevated plasma cortisol levels on day 29 compared to No, while on day 58 cortisol levels were higher in the control group. Additionally, both poly I:C and the Vibrio vaccine gave significantly increased cortisol levels one day post-injection compared to PBS treated controls, irrespective of previous oxygen exposure. Invitro stimulation of macrophages with poly I:C revealed higher IFNα mRNA levels at 6, 12 and 24h and for Mx at 12 and 24h post-stimulation, for both No and Hy individuals. Moreover, IFNα levels were higher in No than in Hy individuals at all time points, and a similar difference was seen in Mx at 48h. Invivo stimulation with poly I:C elicited strong elevation of the IL-1β, IFNγ, Mx and IP10 mRNA transcripts in head kidney, while TNFα1 and IFNα were found unaffected. The Vibrio vaccine elicited a strong up regulation of IL-1β, IFNγ and IP10 mRNA, whereas Mx, TNFα1 and IFNα appeared unchanged. Significant differences in expression between different oxygen exposure groups were found for all genes and both stimuli. The overall trend suggests that long-term hypoxia either reduces or delays the expression of these genes in head kidney. Expression of IFNγ and Mx in intestinal tissues also showed a strong up regulation of the genes following poly I:C stimulation, and also here the overall trend suggests that chronic hypoxia results in a lower or delayed expression of the measured genes. In summary, our results indicate that chronic hypoxia modulates the expression of important immune related genes putatively altering the immune response. As the effect is present in isolated macrophages as well as head kidney and intestinal tissue the modulation appears to be affecting local as well as systemic responses.
11.	Niklasson, Lars, et al. (author) Disturbance of the intestinal mucosal immune system of farmed Atlantic salmon (Salmo salar), in response to long-term hypoxic conditions 2011 In: FISH & SHELLFISH IMMUNOLOGY. - 1050-4648. ; 31:6, s. 1072-1080 Journal article (peer-reviewed)
12.	Niklasson, Lars, et al. (author) Effects of Cortisol on the Intestinal Mucosal Immune Response during Cohabitant Challenge with IPNV in Atlantic Salmon (Salmo salar) 2014 In: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 9:5 Journal article (peer-reviewed)abstract Infectious pancreatic necrosis virus (IPNV) causes high incidence of disease in salmonids during the first period after SW transfer. During this period as well as during periods of stress, cortisol levels increase and indications of a relationship between IPNV susceptibility and cortisol have been suggested. The intestine is an entry route and a target tissue for IPNV displaying severe enteritis and sloughing of the mucosa in infected fish. The mechanisms behind effects of the virus on the intestinal tissue and the impact of cortisol on the effect remain unclear. In the present study, Atlantic salmon post smolts treated with or without slow release cortisol implants were subjected to a cohabitant IPNV challenge. Analysis of genes and proteins related to the innate and acquired immune responses against virus was performed 6 days post-challenge using qPCR and immunohistochemistry. An increased mRNA expression of anti-viral cytokine interferon type I was observed in the proximal intestine and head kidney as a response to the viral challenge and this effect was suppressed by cortisol. No effect was seen in the distal intestine. T-cell marker CD3 as well as MHC-I in both intestinal regions and in the head kidney was down regulated at the mRNA level. Number of CD8 alpha lymphocytes decreased in the proximal intestine in response to cortisol. On the other hand, mRNA expression of Mx and IL-1 beta increased in the proximal intestine and head kidney in IPNV challenged fish in the presence of cortisol suggesting that the immune activation shifts in timing and response pathway during simulated stress. The present study clearly demonstrates that IPNV infection results in a differentiated epithelial immune response in the different intestinal regions of the Atlantic salmon. It also reveals that the epithelial immune response differs from the systemic, but that both are modulated by the stress hormone cortisol.
13.	Nilsen, Tom Ole, et al. (author) EFFECTS OF ANDROGENS AND CORTISOL ON GILL ION TRANSPORTERS AND OMSMOREGULATORY CAPACITY IN ATLANTIC SALMON (SALMO SALAR) 2014 In: ICBF 2014, Edinburgh. Conference paper (other academic/artistic)abstract Sex steroids have been reported to compromise ion homeostasis in teleosts, yet there is limited and somewhat contradicting knowledge about the mechanisms through which androgens impact osmoregulatory capacity in salmonids. Immature Atlantic salmon post-smolts in seawater (SW) were injected with 11-ketoandrostenedione (OA; 25 µg/g BW), cortisol (F; 25 µg/g BW), F+OA (25 µg/g BW) and sham control (CON). After 8 days treatment, androgen treated fishdemonstrated a striking transcriptional increase in freshwater (FW)-type of ion transporters (NKA α1a ) , concurrent with no apparent ion perturbations, or down regulation of SW gill ion-transporters (NKA α1b). F treated post-smolts displayed increased gill NKA α1a transcription, with an additive effect of F+OA.. Moreover, F also resulted in decreased transcription of NKA α1b whilst fish treated with combinations of F and OA experienced severe ion perturbations and mortalities in SW, while no mortality occurred when only F was administered. Our findings suggests that androgens have, either directly or indirectly, a role in remodelling the gill epithelia for FW entry, rather than leading to osmoregulatory dysfunction in SW acclimated post-smolts. Moreover, maturing post-smolts may be sensitive to stress since combinations of elevated androgens and cortisol levels may have detrimental effects on homeostasis and fish welfare.
14.	Padra, János T, et al. (author) Aeromonas salmonicida Binds Differentially to Mucins Isolated from Skin and Intestinal Regions of Atlantic Salmon in an N-Acetylneuraminic Acid-Dependent Manner. 2014 In: Infection and immunity. - 1098-5522. ; 82:12, s. 5235-45 Journal article (peer-reviewed)abstract Aeromonas salmonicida subsp. salmonicida infection, also known as furunculosis disease, is associated with high morbidity and mortality in salmonid aquaculture. The first line of defense the pathogen encounters is the mucus layer, which is predominantly comprised of secreted mucins. Here we isolated and characterized mucins from the skin and intestinal tract of healthy Atlantic salmon and studied how A. salmonicida bound to them. The mucins from the skin, pyloric ceca, and proximal and distal intestine mainly consisted of mucins soluble in chaotropic agents. The mucin density and mucin glycan chain length from the skin were lower than were seen with mucin from the intestinal tract. A. salmonicida bound to the mucins isolated from the intestinal tract to a greater extent than to the skin mucins. The mucins from the intestinal regions had higher levels of sialylation than the skin mucins. Desialylating intestinal mucins decreased A. salmonicida binding, whereas desialylation of skin mucins resulted in complete loss of binding. In line with this, A. salmonicida also bound better to mammalian mucins with high levels of sialylation, and N-acetylneuraminic acid appeared to be the sialic acid whose presence was imperative for binding. Thus, sialylated structures are important for A. salmonicida binding, suggesting a pivotal role for sialylation in mucosal defense. The marked differences in sialylation as well as A. salmonicida binding between the skin and intestinal tract suggest interorgan differences in the host-pathogen interaction and in the mucin defense against A. salmonicida.
15.	Padra, János T, et al. (author) Aeromonas salmonicida proliferation and quorum sensing in response to mucins isolated from Atlantic salmon skin and intestine 2014 In: ICBF 2014, 11th International Congress on the Biology of Fish, 3-7 August, 2014, Edinburgh, Scotland.. Conference paper (other academic/artistic)
16.	Padra, János T, et al. (author) Aeromonas salmonicida ssp. salmonicida binds differentially to mucins isolated from skin and intestinal organs of Atlantic salmon in an N-acetylneuraminic acid dependent manner 2014 In: ICBF 2014, Edinburgh. Conference paper (other academic/artistic)
17.	rakers, s, et al. (author) Antimicrobial peptides (AMPs) from fish epidermis: Perspectives for investigative dermatology 2013 In: Journal of Investigative Dermatology. - 0022-202X. ; 133, s. 1140-1149 Research review (peer-reviewed)abstract Mammalian and fish skin share protective activities against environments that are rich in infectious agents. Fish epidermis is endowed with an extrinsic barrier consisting of a mucus layer and antimicrobial peptides (AMPs). These operate together as a protective chemical shield. As these AMPs are evolutionarily well preserved and also found in higher vertebrate skin (including human epidermis), fish skin offers a unique opportunity to study the origins of innate antimicrobial defense systems. Furthermore, the broad spectrum of fish mucus antimicrobial activities renders piscine AMPs interesting to investigative dermatology, as these may become exploitable for various indications in clinical dermatology. Therefore, this article aims at casting light on fish mucus, the evolutionary relationship between human and fish AMPs, and the latter’s antibacterial, antifungal, and even antiviral activities. Moreover, we develop dermatological lessons from, and sketch potential future clinical applications of, fish mucus and piscine AMPs.
18.	Sandblom, Erik, 1978, et al. (author) Effects of electric field exposure on blood pressure, cardioventilatory activity and the physiological stress response in Arctic char, Salvelinus alpinus L. 2012 In: Aquaculture. - : Elsevier BV. - 0044-8486 .- 1873-5622. ; 344-349, s. 135-140 Journal article (peer-reviewed)abstract Electric field exposure is used to stun or immobilize fish prior to slaughter in the aquaculture industry and for field sampling purposes (i.e. electrofishing), but the physiological response of fish to this exposure is incompletely understood. In this paper we report on changes in blood pressure, heart and ventilation rates, and hematological variables in chronically cannulated Arctic char (Salvelinus alpinus) in response to exposure to an electric field of 4 V/cm (125 Hz) for 5 and 30 s. Both durations of exposure resulted in a brief (total duration: 5.2 to 6.0 s, respectively) four-fold blood pressure increase above resting levels. The 5 s exposure was followed by a period of cardiac and ventilatory arrest (for 35 and 176 s on average, respectively), but cardioventilatory activity recovered in ten out of eleven fish. Nevertheless, signs of systemic stress responses were evident after the exposure. These included moderate hypertension, increased ventilation amplitude, increased plasma cortisol levels and altered hydromineral balance. After the 30 s exposure, cardiac activity initially appeared to recover, but subsequently declined. Ventilation did not recover. It is suggested that circulatory failure due to cardiac ischemia resulting from ventilatory failure; rather than instantaneous and irrecoverable cardiac arrest from the electric field exposure per se, is the ultimate cause of death in fish that fail to recover from exposure to an electric field in water. The brief dramatic hypertension observed in char may partly explain the haemorrhages that are frequently observed in electrically stunned fish of some species.
19.	Sandblom, Erik, 1978, et al. (author) Stress responses in Arctic char (Salvelinus alpinus L.) during hyperoxic carbon dioxide immobilization relevant to aquaculture 2013 In: Aquaculture. - : Elsevier BV. - 0044-8486 .- 1873-5622. ; 414–415, s. 254-259 Journal article (peer-reviewed)abstract Physiological responses during immobilization with hyperoxic hypercapnia were determined in cannulated Arctic char (Salvelinus alpinus) exposed for 10 min to mixtures of 10% CO2 in 90% O2 (10:90) or 50% CO2 in 50% O2 (50:50). Results were compared with a previous study on the same group of char using pure CO2 under identical experimental conditions to test the hypothesis that supplemental oxygen may reduce stress and improve welfare during CO2 exposure. While all fish recovered from the two exposures, the time to loss of equilibrium with the 50:50 mixture was significantly shorter than for the 10:90 mixture (143 vs. 276 s); and the time to regain equilibrium was longer (2302 vs. 963 s). Hypertension and bradycardia developed with 10:90, while 50:50 resulted in tachycardia and unchanged blood pressure. Ventilation frequency and amplitude increased significantly with 10:90, whereas ventilation ceased completely with 50:50. Primary and secondary stress responses were evident during recovery in normoxia in both groups as indicated by elevated heart rate and ventilation and increased plasma cortisol. However, recovery appeared to be faster with the 10:90 mixture because ventilation amplitude and plasma cortisol levels declined more rapidly. Nonetheless, the times to loss of equilibrium recorded here with mixtures of oxygen and carbon dioxide bracket that observed previously with pure CO2. Furthermore, the increase in plasma cortisol was similar or higher in the present study suggesting that while supplemental oxygen does not markedly reduce stress or improve welfare during carbon dioxide immobilization, survival and recovery in normoxia are improved.
20.	Segner, Helmut, et al. (author) Health of farmed fish: its relation to fish welfare and its utility as welfare indicator 2012 In: Fish Physiology and Biochemistry. - : Springer Science and Business Media LLC. - 0920-1742 .- 1573-5168. ; 38:1, s. 85-105 Journal article (peer-reviewed)abstract This brief review focuses on health and biological function as cornerstones of fish welfare. From the function-based point of view, good welfare is reflected in the ability of the animal to cope with infectious and non-infectious stressors, thereby maintaining homeostasis and good health, whereas stressful husbandry conditions and protracted suffering will lead to the loss of the coping ability and, thus, to impaired health. In the first part of the review, the physiological processes through which stressful husbandry conditions modulate health of farmed fish are examined. If fish are subjected to unfavourable husbandry conditions, the resulting disruption of internal homeostasis necessitates energy-demanding physiological adjustments (allostasis/acclimation). The ensuing energy drain leads to trade-offs with other energy-demanding processes such as the functioning of the primary epithelial barriers (gut, skin, gills) and the immune system. Understanding of the relation between husbandry conditions, allostatic responses and fish health provides the basis for the second theme developed in this review, the potential use of biological function and health parameters as operational welfare indicators (OWIs). Advantages of function-and health-related parameters are that they are relatively straightforward to recognize and to measure and are routinely monitored in most aquaculture units, thereby providing feasible tools to assess fish welfare under practical farming conditions. As the efforts to improve fish welfare and environmental sustainability lead to increasingly diverse solutions, in particular integrated production, it is imperative that we have objective OWIs to compare with other production forms, such as high-density aquaculture. However, to receive the necessary acceptance for legislation, more robust scientific backing of the health-and function-related OWIs is urgently needed.
21.	Seth, Henrik, 1979, et al. (author) Physiological responses and welfare implications of rapid hypothermia and immobilization with high levels of CO2 at two temperatures in Arctic char (Salvelinus alpinus). 2013 In: Aquaculture. - : Elsevier BV. - 0044-8486 .- 1873-5622. ; 402-403, s. 146-151 Journal article (peer-reviewed)abstract Carbon dioxide (CO2) is used for immobilisation of Arctic char (Salvelinus alpinus) prior to slaughter at Swedish aquaculture facilities, and fish are routinely exposed to hypothermia in ice water during transport. Yet, information on stress physiological responses to CO2, temperature extremes and their potential interacting effects is scarce for this cold-water species. Here, blood pressure, heart and ventilation rates and plasma variables including ions, haematocrit, glucose and cortisol were measured in cannulated char during exposure to hypothermia (i.e. a rapid temperature drop from 10 °C to 0.25 °C); as well as to water nearly saturated with CO2 at 10 °C and 0.25 °C to test the hypothesis that hypothermia alleviates stress responses during CO2 exposure. While all fish maintained equilibrium during the 30 min hypothermic challenge, blood pressure, heart and ventilation rates decreased and plasma cortisol increased moderately. CO2 exposure at 10 and 0.25 °C resulted in aversive behavioural reactions before equilibrium was irrecoverably lost after 184 ± 14 and 191 ± 9 s, respectively. The physiological responses to CO2 exposure were largely similar at both temperatures with elevated cortisol levels, reduced heart and ventilation rates and hypotension; although reductions in ventilation amplitude and arterial pulse pressure were significantly more pronounced at 0.25 °C. It is concluded that hypothermia alone is a relatively mild stressor in this species, while CO2 exposure elicits pronounced physiological and behavioural stress responses that are not alleviated by hypothermia.
22.	Sundell, Kristina, 1959, et al. (author) Intestinal absorption 2011 In: Encyclopedia of Fish Physiology: From Genome to Environent. - London : Academic Press, an imprint of Elsevier. - 9780080923239 ; , s. 1311-1321 Book chapter (peer-reviewed)abstract The fish intestine is the main site of absorption. The functional morphology and physiology of the intestinal epithelium have evolved to selectively absorb essential nutrients as well as water and ions from the ingested food and water, while preventing entrance of harmful substances. Membrane-bound transport and channel proteins together with endocytotic mechanisms ensure a well-controlled uptake. Being a multifunctional tissue, there is a constant balance between the different physiological tasks of the intestinal epithelium, and both internal and external factors can affect and control these events that are of fundamental importance for development, growth, and performance of the fish.
23.	Sundell, Kristina, 1959, et al. (author) Intestinal fluid absorption in anadromous salmonids: importance of tight junctions and aquaporins. 2012 In: Frontiers in physiology. - : Frontiers Media SA. - 1664-042X. ; 3 Research review (peer-reviewed)abstract The anadromous salmonid life cycle includes both fresh water (FW) and seawater (SW) stages. The parr-smolt transformation (smoltification) pre-adapt the fish to SW while still in FW. The osmoregulatory organs change their mode of action from a role of preventing water inflow in FW, to absorb ions to replace water lost by osmosis in SW. During smoltification, the drinking rate increases, in the intestine the ion and fluid transport increases and is further elevated after SW entry. In SW, the intestine absorbs ions to create an inwardly directed water flow which is accomplished by increased Na(+), K(+)-ATPase (NKA) activity in the basolateral membrane, driving ion absorption via ion channels and/or co-transporters. This review will aim at discussing the expression patterns of the ion transporting proteins involved in intestinal fluid absorption in the FW stage, during smoltification and after SW entry. Of equal importance for intestinal fluid absorption as the active absorption of ions is the permeability of the epithelium to ions and water. During the smoltification the increase in NKA activity and water uptake in SW is accompanied by decreased paracellular permeability suggesting a redirection of the fluid movement from a paracellular route in FW, to a transcellular route in SW. Increased transcellular fluid absorption could be achieved by incorporation of aquaporins (AQPs) into the enterocyte membranes and/or by a change in fatty acid profile of the enterocyte lipid bilayer. An increased incorporation of unsaturated fatty acids into the membrane phospholipids will increase water permeability by enhancing the fluidity of the membrane. A second aim of the present review is therefore to discuss the presence and regulation of expression of AQPs in the enterocyte membrane as well as to discuss the profile of fatty acids present in the membrane phospholipids during different stages of the salmonid lifecycle.
24.	Sundh, Henrik, 1976, et al. (author) Development of intestinal ion-transporting mechanisms during smoltification and seawater acclimation in Atlantic salmon Salmo salar 2014 In: Journal of Fish Biology. - : Wiley. - 0022-1112. ; 85:4, s. 1227-1252 Journal article (peer-reviewed)abstract This study investigated the expression of ion transporters involved in intestinal fluid absorption and presents evidence for developmental changes in abundance and tissue distribution of these transporters during smoltification and seawater (SW) acclimation of Atlantic salmon Salmo salar. Emphasis was placed on Na+, K+-ATPase (NKA) and Na+, K+, Cl- co-transporter (NKCC) isoforms, at both transcriptional and protein levels, together with transcription of chloride channel genes. The nka alpha 1c was the dominant isoform at the transcript level in both proximal and distal intestines; also, it was the most abundant isoform expressed in the basolateral membrane of enterocytes in the proximal intestine. This isoform was also abundantly expressed in the distal intestine in the lower part of the mucosal folds. The protein expression of intestinal Nka alpha 1c increased during smoltification. Immunostaining was localized to the basal membrane of the enterocytes in freshwater (FW) fish, and re-distributed to a lateral position after SW entry. Two other Nka isoforms, alpha 1a and alpha 1b, were expressed in the intestine but were not regulated to the same extent during smoltification and subsequent SW transfer. Their localization in the intestinal wall indicates a house-keeping function in excitatory tissues. The absorptive form of the NKCC-like isoform (sub-apically located NKCC2 and/or Na+, Cl(-)co-transporter) increased during smoltification and further after SW transfer. The cellular distribution changed from a diffuse expression in the sub-apical regions during smoltification to clustering of the transporters closer to the apical membrane after entry to SW. Furthermore, transcript abundance indicates that the mechanisms necessary for exit of chloride ions across the basolateral membrane and into the lateral intercellular space are present in the form of one or more of three different chloride channels: cystic fibrosis transmembrane conductance regulator I and II and chloride channel 3.
25.	Sundh, Henrik, 1976, et al. (author) Intestinal barrier function of Atlantic salmon (Salmo salar L.) post smolts is reduced by common sea cage environments and suggested as a possible physiological welfare indicator 2010 In: BMC Physiology. - : Springer Science and Business Media LLC. - 1472-6793. ; 10 Journal article (peer-reviewed)abstract Background Fish farmed under high intensity aquaculture conditions are subjected to unnatural environments that may cause stress. Therefore awareness of how to maintain good health and welfare of farmed fish is important. For Atlantic salmon held in sea cages, water flow, dissolved oxygen (DO) levels and temperature will fluctuate over time and the fish can at times be exposed to detrimentally low DO levels and high temperatures. This experimental study investigates primary and secondary stress responses of Atlantic salmon post smolts to long-term exposure to reduced and fluctuating DO levels and high water temperatures, mimicking situations in the sea cages. Plasma cortisol levels and cortisol release to the water were assessed as indicators of the primary stress response and intestinal barrier integrity and physiological functions as indicators of secondary responses to changes in environmental conditions. Results Plasma cortisol levels were elevated in fish exposed to low (50% and 60% saturation) DO levels and low temperature (9°C), at days 9, 29 and 48. The intestinal barrier function, measured as electrical resistance (TER) and permeability of mannitol at the end of the experiment, were reduced at 50% DO, in both proximal and distal intestine. When low DO levels were combined with high temperature (16°C), plasma cortisol levels were elevated in the cyclic 1:5 h at 85%:50% DO group and fixed 50% DO group compared to the control (85% DO) group at day 10 but not at later time points. The intestinal barrier function was clearly disturbed in the 50% DO group; TER was reduced in both intestinal regions concomitant with increased paracellular permeability in the distal region. Conclusions This study reveals that adverse environmental conditions (low water flow, low DO levels at low and high temperature), that can occur in sea cages, elicits primary and secondary stress responses in Atlantic salmon post smolts. The intestinal barrier function was significantly affected by prolonged hypoxic stress even when no primary stress response was observed. This suggests that intestinal barrier function is a good experimental marker for evaluation of chronic stress and that it can be a valuable tool to study the impact of various husbandry conditions on health and welfare of farmed Atlantic salmon.

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