| 1. |
- Clark, M. S., et al.
(författare)
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Deciphering mollusc shell production: the roles of genetic mechanisms through to ecology, aquaculture and biomimetics
- 2020
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Ingår i: Biological Reviews. - : Wiley. - 1464-7931 .- 1469-185X. ; 95:6, s. 1812-37
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Tidskriftsartikel (refereegranskat)abstract
- Most molluscs possess shells, constructed from a vast array of microstructures and architectures. The fully formed shell is composed of calcite or aragonite. These CaCO(3)crystals form complex biocomposites with proteins, which although typically less than 5% of total shell mass, play significant roles in determining shell microstructure. Despite much research effort, large knowledge gaps remain in how molluscs construct and maintain their shells, and how they produce such a great diversity of forms. Here we synthesize results on how shell shape, microstructure, composition and organic content vary among, and within, species in response to numerous biotic and abiotic factors. At the local level, temperature, food supply and predation cues significantly affect shell morphology, whilst salinity has a much stronger influence across latitudes. Moreover, we emphasize how advances in genomic technologies [e.g. restriction site-associated DNA sequencing (RAD-Seq) and epigenetics] allow detailed examinations of whether morphological changes result from phenotypic plasticity or genetic adaptation, or a combination of these. RAD-Seq has already identified single nucleotide polymorphisms associated with temperature and aquaculture practices, whilst epigenetic processes have been shown significantly to modify shell construction to local conditions in, for example, Antarctica and New Zealand. We also synthesize results on the costs of shell construction and explore how these affect energetic trade-offs in animal metabolism. The cellular costs are still debated, with CaCO(3)precipitation estimates ranging from 1-2 J/mg to 17-55 J/mg depending on experimental and environmental conditions. However, organic components are more expensive (similar to 29 J/mg) and recent data indicate transmembrane calcium ion transporters can involve considerable costs. This review emphasizes the role that molecular analyses have played in demonstrating multiple evolutionary origins of biomineralization genes. Although these are characterized by lineage-specific proteins and unique combinations of co-opted genes, a small set of protein domains have been identified as a conserved biomineralization tool box. We further highlight the use of sequence data sets in providing candidate genes forin situlocalization and protein function studies. The former has elucidated gene expression modularity in mantle tissue, improving understanding of the diversity of shell morphology synthesis. RNA interference (RNAi) and clustered regularly interspersed short palindromic repeats - CRISPR-associated protein 9 (CRISPR-Cas9) experiments have provided proof of concept for use in the functional investigation of mollusc gene sequences, showing for example that Pif (aragonite-binding) protein plays a significant role in structured nacre crystal growth and that theLsdia1gene sets shell chirality inLymnaea stagnalis. Much research has focused on the impacts of ocean acidification on molluscs. Initial studies were predominantly pessimistic for future molluscan biodiversity. However, more sophisticated experiments incorporating selective breeding and multiple generations are identifying subtle effects and that variability within mollusc genomes has potential for adaption to future conditions. Furthermore, we highlight recent historical studies based on museum collections that demonstrate a greater resilience of molluscs to climate change compared with experimental data. The future of mollusc research lies not solely with ecological investigations into biodiversity, and this review synthesizes knowledge across disciplines to understand biomineralization. It spans research ranging from evolution and development, through predictions of biodiversity prospects and future-proofing of aquaculture to identifying new biomimetic opportunities and societal benefits from recycling shell products.
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| 2. |
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| 3. |
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| 4. |
- Alves, R. N., et al.
(författare)
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Structural and functional maturation of skin during metamorphosis in the Atlantic halibut (Hippoglossus hippoglossus)
- 2018
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Ingår i: Cell and Tissue Research. - : Springer Science and Business Media LLC. - 0302-766X .- 1432-0878. ; 372:3, s. 469-492
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Tidskriftsartikel (refereegranskat)abstract
- To establish if the developmental changes in the primary barrier and osmoregulatory capacity of Atlantic halibut skin are modified during metamorphosis, histological, histochemical, gene expression and electrophysiological measurements were made. The morphology of the ocular and abocular skin started to diverge during the metamorphic climax and ocular skin appeared thicker and more stratified. Neutral mucins were the main glycoproteins produced by the goblet cells in skin during metamorphosis. Moreover, the number of goblet cells producing neutral mucins increased during metamorphosis and asymmetry in their abundance was observed between ocular and abocular skin. The increase in goblet cell number and their asymmetric abundance in skin was concomitant with the period that thyroid hormones (THs) increase and suggests that they may be under the control of these hormones. Several mucin transcripts were identified in metamorphosing halibut transcriptomes and Muc18 and Muc5AC were characteristic of the body skin. Na+, K+-ATPase positive (NKA) cells were observed in skin of all metamorphic stages but their number significantly decreased with the onset of metamorphosis. No asymmetry was observed between ocular and abocular skin in NKA cells. The morphological changes observed were linked to modified skin barrier function as revealed by modifications in its electrophysiological properties. However, the maturation of the skin functional characteristics preceded structural maturation and occurred at stage 8 prior to the metamorphic climax. Treatment of Atlantic halibut with the THs disrupter methimazole (MMI) affected the number of goblet cells producing neutral mucins and the NKA cells. The present study reveals that the asymmetric development of the skin in Atlantic halibut is TH sensitive and is associated with metamorphosis and that this barrier's functional properties mature earlier and are independent of metamorphosis.
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| 5. |
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| 6. |
- Benktander, John, et al.
(författare)
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Effects of Size and Geographical Origin on Atlantic salmon, Salmo salar, Mucin O-Glycan Repertoire
- 2019
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Ingår i: Molecular & Cellular Proteomics. - 1535-9476. ; 18:6, s. 1183-1196
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Tidskriftsartikel (refereegranskat)abstract
- Diseases cause ethical concerns and economic losses in the Salmonid industry. The mucus layer comprised of highly O-glycosylated mucins is the first contact between pathogens and fish. Mucin glycans govern pathogen adhesion, growth and virulence. The Atlantic salmon O-glycome from a single location has been characterized and the interindividual variation was low. Because interindividual variation is considered a population-based defense, hindering the entire population from being wiped out by a single infection, low interindividual variation among Atlantic salmon may be a concern. Here, we analyzed the O-glycome of 25 Atlantic salmon from six cohorts grown under various conditions from Sweden, Norway and Australia (Tasmania) using mass spectrometry. This expanded the known Atlantic salmon O-glycome by 60% to 169 identified structures. The mucin O-glycosylation was relatively stable over time within a geographical region, but the size of the fish affected skin mucin glycosylation. The skin mucin glycan repertoires from Swedish and Norwegian Atlantic salmon populations were closely related compared with Tasmanian ones, regardless of size and salinity, with differences in glycan size and composition. The internal mucin glycan repertoire also clustered based on geographical origin and into pyloric cecal and distal intestinal groups, regardless of cohort and fish size. Fucosylated structures were more abundant in Tasmanian pyloric caeca and distal intestine mucins compared with Swedish ones. Overall, Tasmanian Atlantic salmon mucins have more O-glycan structures in skin but less in the gastrointestinal tract compared with Swedish fish. Low interindividual variation was confirmed within each cohort. The results can serve as a library for identifying structures of importance for host-pathogen interactions, understanding population differences of salmon mucin glycosylation in resistance to diseases and during breeding and selection of strains. The results could make it possible to predict potential vulnerabilities to diseases and suggest that inter-region breeding may increase the glycan diversity.
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| 7. |
- Benktander, John, et al.
(författare)
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Gill Mucus and Gill Mucin O-glycosylation in Healthy and Amebic Gill Disease-Affected Atlantic Salmon.
- 2020
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Ingår i: Microorganisms. - : MDPI AG. - 2076-2607. ; 8:12
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Tidskriftsartikel (refereegranskat)abstract
- Amoebic gill disease (AGD) causes poor performance and death in salmonids. Mucins are mainly comprised by carbohydrates and are main components of the mucus covering the gill. Since glycans regulate pathogen binding and growth, glycosylation changes may affect susceptibility to primary and secondary infections. We investigated gill mucin O-glycosylation from Atlantic salmon with and without AGD using liquid chromatography-mass spectrometry. Gill mucin glycans were larger and more complex, diverse and fucosylated than skin mucins. Confocal microscopy revealed that fucosylated mucus coated sialylated mucus strands in ex vivo gill mucus. Terminal HexNAcs were more abundant among O-glycans from AGD-affected Atlantic salmon, whereas core 1 structures and structures with acidic moieties such as N-acetylneuraminic acid (NeuAc) and sulfate groups were less abundant compared to non-infected fish. The fucosylated and NeuAc-containing O-glycans were inversely proportional, with infected fish on the lower scale of NeuAc abundance and high on fucosylated structures. The fucosylated epitopes were of three types: Fuc-HexNAc-R, Gal-[Fuc-]HexNAc-R and HexNAc-[Fuc-]HexNAc-R. These blood group-like structures could be an avenue to diversify the glycan repertoire to limit infection in the exposed gills. Furthermore, care must be taken when using skin mucus as proxy for gill mucus, as gill mucins are distinctly different from skin mucins.
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| 8. |
- Benktander, John, et al.
(författare)
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Stress impairs skin barrier function and induces α2-3 linked n-acetylneuraminic acid and core 1 o-glycans on skin mucins in atlantic salmon, salmo salar
- 2021
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 22:3
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Tidskriftsartikel (refereegranskat)abstract
- © 2021 by the authors. Licensee MDPI, Basel, Switzerland. The skin barrier consists of mucus, primarily comprising highly glycosylated mucins, and the epithelium. Host mucin glycosylation governs interactions with pathogens and stress is associated with impaired epithelial barrier function. We characterized Atlantic salmon skin barrier function during chronic stress (high density) and mucin O-glycosylation changes in response to acute and chronic stress. Fish held at low (LD: 14–30 kg/m3) and high densities (HD: 50-80 kg/m3) were subjected to acute stress 24 h before sampling at 17 and 21 weeks after start of the experiment. Blood parameters indicated primary and secondary stress responses at both sampling points. At the second sampling, skin barrier function towards molecules was reduced in the HD compared to the LD group (Papp mannitol; p < 0.01). Liquid chromatography–mass spectrometry revealed 81 O-glycan structures from the skin. Fish subjected to both chronic and acute stress had an increased proportion of large O-glycan structures. Overall, four of the O-glycan changes have potential as indicators of stress, especially for the combined chronic and acute stress. Stress thus impairs skin barrier function and induces glycosylation changes, which have potential to both affect interactions with pathogens and serve as stress indicators.
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| 9. |
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| 10. |
- Bornehag, CG, et al.
(författare)
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Dampness in buildings as a risk factor for health effects, EUROEXPO: a multidisciplinary review of the literature (1998-2000) on dampness and mite exposure in buildings and health effects
- 2004
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Ingår i: Indoor Air. - : Hindawi Limited. - 0905-6947 .- 1600-0668. ; 14:4, s. 243-257
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Forskningsöversikt (refereegranskat)abstract
- The scientific literature on health effects from dampness in buildings, including mite exposure over the period 1998-2000 has been reviewed by a European group (EUROEXPO) of eight scientists in experience from medicine, epidemiology, toxicology and engineering. Forty studies deemed relevant have been the foundation for the conclusions. Dampness in buildings is a risk factor for health effects among atopics and non-atopics both in domestic and in public environments. However, the literature is not conclusive in respect of causative agents, e.g. mites, microbiological agents and organic chemicals from degraded building materials. There is a strong need for more multidisciplinary studies including expertise from all relevant areas. A general conclusion from the work was that there is a strong need for multidisciplinary reviews in scientific journals of articles dealing with associations between indoor environmental factors and health effects.
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| 11. |
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| 12. |
- Bornehag, C G, et al.
(författare)
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'Dampness' at home and its association with airway, nose, and skin symptoms among 10,851 preschool children in Sweden: a cross-sectional study.
- 2005
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Ingår i: Indoor air. - : Hindawi Limited. - 0905-6947 .- 1600-0668. ; 15 Suppl 10, s. 48-55
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Tidskriftsartikel (refereegranskat)abstract
- There is convincing epidemiological evidence that 'dampness' in buildings is associated with respiratory effects. In order to identify health-relevant exposures in buildings with 'dampness', the study 'Dampness in Buildings and Health' (DBH) was initiated. In the first step of the study, cross-sectional data on home characteristics including 'dampness' problems, and symptoms in airway, nose, and skin among 10,851 children (1-6 years), were collected by means of a questionnaire to the parents. The prevalence of wheezing during the last 12 months was 18.9% and doctor-diagnosed asthma 5.4%. Rhinitis during the last 12 months was reported for 11.1% of the children and eczema during the last 12 months 18.7%. Gender, allergic symptoms among parents, and age of the child were associated with symptoms. Water leakage was reported in 17.8% of the buildings, condensation on windows in 14.3%, and detached flooring materials in 8.3%. Visible mould or damp spots were reported in only 1.5% of the buildings. The four 'dampness' indices were associated to higher prevalence of symptoms in both crude and adjusted analysis. Furthermore, it was found that the combination of water leakage in the home and PVC as flooring material in the child's or parent's bedroom was associated to higher prevalence of symptoms among children. However, the interpretation of this finding is unclear. The combination of water leakage and PVC may be a proxy, for example, reconstruction because of water damages. PRACTICAL IMPLICATIONS: The study have showed that moisture-related problems in buildings are a risk factor for asthma and allergic symptoms among preschool children. The recommendation to the general public is to remediate damp buildings.
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| 13. |
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| 14. |
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| 15. |
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| 16. |
- Bornehag, Carl-Gustaf, 1957-, et al.
(författare)
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Phthalates in indoor dust indoor and their association to building characteristics
- 2005
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Ingår i: Journal of Environmental Health Perspectives. - : Environmental Health Perspectives. - 0091-6765 .- 1552-9924. ; 113:10, s. 1399-1404-
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Tidskriftsartikel (refereegranskat)abstract
- In a recent study of 198 Swedish children with persistent allergic symptoms and 202 controls without such symptoms, we reported associations between the symptoms and the concentrations of n-butyl benzyl phthalate (BBzP) and di(2-ethylhexyl) phthalate (DEHP) in dust taken from the childrens' bedrooms. In the present study we examined associations between the concentrations of different phthalate esters in the dust from these bedrooms and various characteristics of the home. The study focused on BBzP and DEHP because these were the phthalates associated with health complaints. Associations have been examined using parametric and nonparametric tests as well as multiple logistic regression. For both BBzP and DEHP, we found associations between their dust concentrations and the amount of polyvinyl chloride (PVC) used as flooring and wall material in the home. Furthermore, high concentrations of BBzP (above median) were associated with self-reported water leakage in the home, and high concentrations of DEHP were associated with buildings constructed before 1960. Other associations, as well as absence of associations, are reported. Both BBzP and DEHP were found in buildings with neither PVC flooring nor wall covering, consistent with the numerous additional plasticized materials that are anticipated to be present in a typical home. The building characteristics examined in this study cannot serve as complete proxies for these quite varied sources. However, the associations reported here can help identify homes where phthalate concentrations are likely to be elevated and can aid in developing mitigation strategies.
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| 17. |
- Bornehag, Carl-Gustaf, 1957-, et al.
(författare)
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Potential selection biases
- 2005
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Ingår i: Journal of Environmental Health Perspectives. - 0091-6765 .- 1552-9924. ; 112, s. 1393-1397
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Tidskriftsartikel (refereegranskat)
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| 18. |
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| 19. |
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| 20. |
- Camponeschi, Alessandro, et al.
(författare)
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Human CD38 regulates B cell antigen receptor dynamic organization in normal and malignant B cells.
- 2022
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Ingår i: The Journal of experimental medicine. - : Rockefeller University Press. - 1540-9538 .- 0022-1007. ; 219:9
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Tidskriftsartikel (refereegranskat)abstract
- CD38 is a multifunctional protein expressed on the surface of B cells in healthy individuals but also in B cell malignancies. Previous studies have suggested a connection between CD38 and components of the IgM class B cell antigen receptor (IgM-BCR) and its coreceptor complex. Here, we provide evidence that CD38 is closely associated with CD19 in resting B cells and with the IgM-BCR upon engagement. We show that targeting CD38 with an antibody, or removing this molecule with CRISPR/Cas9, inhibits the association of CD19 with the IgM-BCR, impairing BCR signaling in normal and malignant B cells. Together, our data suggest that CD38 is a new member of the BCR coreceptor complex, where it exerts a modulatory effect on B cell activation upon antigen recognition by regulating CD19. Our study also reveals a new mechanism where α-CD38 antibodies could be a valuable option in therapeutic approaches to B cell malignancies driven by aberrant BCR signaling.
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| 21. |
- 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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| 22. |
- Ellis, T, et al.
(författare)
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Non-invasive measurement of cortisol and melatonin in tanks stocked with seawater Atlantic salmon
- 2007
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Ingår i: Aquaculture. - : Elsevier BV. - 0044-8486. ; 272:1-4, s. 698-706
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Tidskriftsartikel (refereegranskat)abstract
- This study examined the potential for non-invasive assessment of cortisol and melatonin status of seawater Atlantic salmon, by measurement of hormone release into the water using methodology developed recently for freshwater rainbow trout. Validation experiments demonstrated good recoveries of spiked cortisol (ca. 95%) and melatonin (ca. 85%) from seawater, that oxygenation of seawater did not affect recovery, and that only small losses occurred during freeze storage of samples. When groups of seawater Atlantic salmon were transferred to experimental tanks, water cortisol concentrations reduced over the first few days — indicating an acclimation response. Subsequent exposure to a handling stress caused a rapid 50-fold increase in water cortisol concentration, followed by a decrease. In a separate experiment, water cortisol levels were elevated in tanks of fish previously exposed to infectious pancreatic necrosis virus, and cortisol release rate was correlated to plasma cortisol level. Water sampling from tanks holding seawater salmon showed that water melatonin concentrations were elevated at night, conforming to expectation. These experiments demonstrate that the cortisol and melatonin status of seawater Atlantic salmon in tanks can be monitored non-invasively by water sampling, with the particular advantage that hormonal status can be tracked over time as the fish are not disturbed by sampling.
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| 23. |
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| 24. |
- Hägerhed-Engman, L, et al.
(författare)
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Low home ventilation rate in combination with mouldy odor from the building structure increase the risk for allergic symptoms in children
- 2009
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Ingår i: Indoor Air. - : Hindawi Limited. - 0905-6947 .- 1600-0668. ; 19:3, s. 184-192
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Tidskriftsartikel (refereegranskat)abstract
- There are consistent findings on associations between asthma and allergy symptoms and residential mold and moisture. However, definitions of ‘dampness’ in studies are diverse because of differences in climate and building construction. Few studies have estimated mold problems inside the building structure by odor assessments. In a nested case-control study of 400 Swedish children, observations and measurements were performed in their homes by inspectors, and the children were examined by physicians for diagnoses of asthma, eczema, and rhinitis. In conclusion, we found an association between moldy odor along the skirting board and allergic symptoms among children, mainly rhinitis. No associations with any of the allergic symptoms were found for discoloured stains, ‘floor dampness’ or a general mold odor in the room. A moldy odor along the skirting board can be a proxy for hidden moisture problem inside the outer wall construction or in the foundation construction. There are indications that such dampness problems increase the risk for sensitization but the interpretation of data in respect of sensitization is difficult as about 80% of the children with rhinitis were sensitized. Furthermore, low ventilation rate in combination with moldy odor along the skirting board further increased the risk for three out of four studied outcomes, indicating that the ventilation rate is an effect modifier for indoor pollutants.
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| 25. |
- Jin, Chunsheng, et al.
(författare)
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Atlantic Salmon Carries a Range of Novel O-Glycan Structures Differentially Localized on Skin and Intestinal Mucins
- 2015
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Ingår i: Journal of Proteome Research. - : American Chemical Society (ACS). - 1535-3893 .- 1535-3907. ; 14:8, s. 3239-3251
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Tidskriftsartikel (refereegranskat)abstract
- Aquaculture is a growing industry, increasing the need for understanding host-pathogen interactions in fish. The skin and mucosal surfaces, covered by a mucus layer composed of mucins, is the first point of contact between fish and pathogens. Highly O-glycosylated mucins have been shown to be an important part of the defense against pathogens, and pathogens bind to host surfaces using lectin-like adhesins. However, knowledge of piscine O-glycosylation is very limited. We characterized mucin O-glycosylation of five freshwater acclimated Atlantic salmon, using mass spectrometry. Of the 109 O-glycans found, most were sialylated and differed in distribution among skin, pyloric ceca, and proximal and distal intestine. Skin O-glycans were shorter (2-6 residues) and less diverse (33 structures) than intestinal O-glycans (2-13 residues, 93 structures). Skin mucins carried O-glycan cores 1, 2, 3, and 5 and three types of sialic acids (Neu5Ac, Neu5Gc, and Kdn) and had sialyl-Tn as the predominant structure. Intestinal mucins carried only cores 1, 2, and 5, Neu5Ac was the only sialic acid present, and sialylated core S was the most dominant structure. This structural characterization can be used for identifying structures of putative importance in host-pathogen interactions for further testing in biological assays and disease intervention therapies.
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| 26. |
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| 27. |
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| 28. |
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| 29. |
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| 30. |
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| 31. |
- Micolucci, Federico, 1984, et al.
(författare)
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Candidatus Scalindua, a Biological Solution to Treat Saline Recirculating Aquaculture System Wastewater
- 2023
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Ingår i: Processes. - : MDPI AG. - 2227-9717. ; 11:3
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Tidskriftsartikel (refereegranskat)abstract
- Recirculating aquaculture systems (RAS) are promising candidates for the sustainable development of the aquaculture industry. A current limitation of RAS is the production and potential accumulation of nitrogenous wastes, ammonium (NH4+), nitrite (NO2-) and nitrate (NO3-), which could affect fish health and welfare. In a previous experiment, we have demonstrated that the marine anammox bacteria Candidatus Scalindua was a promising candidate to treat the wastewater (WW) of marine, cold-water RAS. However, the activity of the bacteria was negatively impacted after a direct exposure to RAS WW. In the current study, we have further investigated the potential of Ca. Scalindua to treat marine RAS WW in a three-phase experiment. In the first phase (control, 83 days), Ca. Scalindua was fed a synthetic feed, enriched in NH4+, NO2- and trace element (TE) mix. Removal rates of 98.9% and 99.6% for NH4+ and NO2-, respectively, were achieved. In the second phase (116 days), we gradually increased the exposure of Ca. Scalindua to nitrogen-enriched RAS WW over a period of about 80 days. In the last phase (79 days), we investigated the needs of TE supplementation for the Ca. Scalindua after they were fully acclimated to 100% RAS WW. Our results show that the gradual exposure of Ca. Scalindua resulted in a successful acclimation to 100% RAS WW, with maintained high removal rates of both NH4+ and NO2- throughout the experiment. Despite a slight decrease in relative abundance (from 21.4% to 16.7%), Ca. Scalindua remained the dominant species in the granules throughout the whole experiment. We conclude that Ca. Scalindua can be successfully used to treat marine RAS WW, without the addition of TE, once given enough time to acclimate to its new substrate. Future studies need to determine the specific needs for optimal RAS WW treatment by Ca. Scalindua at pilot scale.
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| 32. |
- Niklasson, Lars, et al.
(författare)
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Effects of Cortisol on the Intestinal Mucosal Immune Response during Cohabitant Challenge with IPNV in Atlantic Salmon (Salmo salar)
- 2014
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 9:5
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Tidskriftsartikel (refereegranskat)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.
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| 33. |
- Olsen, R. E., et al.
(författare)
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Acute stress alters intestinal function of rainbow trout, Oncorhynchus mykiss (Walbaum)
- 2005
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Ingår i: Aquaculture. - : Elsevier BV. - 0044-8486. ; 250:1-2, s. 480-495
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Tidskriftsartikel (refereegranskat)abstract
- Groups of rainbow trout (Oncorhynchus mykiss Walbaum) in feeding (guts filled with digesta) or food-deprived (3 days of diet deprivation) states were subjected to 15 min of acute stress. Blood samples and intestinal tissue were collected and prepared for physiological, chemical and ultrastructural analysis immediately before stress, and at 4 and 48 h post-stress. Haematocrit, plasma cortisol and lactate levels increased following stress, and the response appeared to be more pronounced in food-deprived than in fed fish. Plasma glucose appeared to increase more in fed fish. Stress did not seem to cause massive tissue damage as measured by cellular leakage of transaminase enzymes into the blood. Furthermore, the plasma oxidative stress marker malondialdehyde did not increase markedly following stress. The content of malondialdehyde did not change following stress neither in midgut nor hindgut sections, and nor did membrane lipid class and fatty acid compositions. Ultrastructural studies showed that stress caused significant widening of the tight junctions between enterocytes in the midgut, with little effect seen in the hindgut. Fed fish appeared to experience more damage than food-deprived fish as judged by the ultrastructural analysis. But these changes were to a large extent transient and cellular organization in the midgut had returned to normal values within 2 days. Intestinal paracellular permeability of the midgut increased 4 h post-stress and was further increased 48 h post-stress of food-deprived fish, whereas no effect was seen in fed trout. In hindgut of food-deprived fish, the permeability appeared to increase sometime after 4 h and was still elevated 48 h after stress. No change in permeability occurred in fed fish. The adherent microbial population level and composition in hindgut was significantly reduced following stress, while the level increased in faeces. This suggests that substantial amounts of mucus are peeled off following stress. It is concluded that, under the present experimental conditions, acute stress causes cellular alteration in rainbow trout gastrointestinal tract. Ultrastructural damages are mainly observed in midgut, but most changes appear to be transient returning to normal levels within 48 h. Changes in adherent intestine microbial population level and compositions together with increased intestinal paracellular permeability following acute stress suggest a possible increased susceptibility to bacterial infections after stress and that active feeding may have a protective role. (C) 2005 Elsevier B.V. All rights reserved.
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| 34. |
- Olsen, R.E., et al.
(författare)
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The acute stress response in fed and food deprived Atlantic cod, Gadus morhua L.
- 2008
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Ingår i: Aquaculture. - : Elsevier BV. - 0044-8486. ; 280:1-4, s. 232-241
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to evaluate the effect of stress and nutritional state (fed vs food deprived) on the generalized stress response and intestinal integrity in Atlantic cod (Gadus morhua L.). Cod in feeding or food deprived states were subjected to 15 min of acute stress (exhaustive exercise). Blood was collected at 9 intervals from before stress (t = 0), to t = 48 h post stress and analysed for blood haematocrit and haemoglobin, and plasma cortisol, lactate, glucose, osmolality, chloride, as well as the tissue damage indicators glutamate oxaloacetate transaminase, glutamate pyruvate transaminase and thiobarbituric acid reactive substances. Intestinal segments were prepared for histology with the same intervals, while assessment of intestinal integrity and microbiology was performed at t = 0, 4 and 48 h post stress. Subjecting cod to exhaustive stress initiated a standard stress response including increased blood Hct and plasma cortisol, glucose, chloride, osmolality and lactate. Food deprived fish did in general have reduced stress resistance compared to fed fish. For many parameters, cod returned slowly to basal levels. Cellular indicators of tissue damage and oxidative stress increased in a biphasic manner following stress. Stress did not affect gut histology but did transiently increase gut permeability. Furthermore, stress had no effect on the adherent bacterial population level in midgut, but did cause a small decrease in hindgut (non-significant) and hindgut chamber (p < 0.05). Isolates belonging to Carnobacterium were predominant but not affected by stress. In conclusion, food deprived cod are less resistant to stress than fed cod. The magnitude of the response is less than in salmonids, but the effects are persistent (including tissue damage indicators and oxidative stress) and may have negative long term consequences. The gut is relatively resistant to stress, there is however a transient increase in the intestinal permeability and alterations in microbiota that may indicate lower protection against invading pathogens.
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| 35. |
- Padra, János T, et al.
(författare)
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Aeromonas salmonicida Binds Differentially to Mucins Isolated from Skin and Intestinal Regions of Atlantic Salmon in an N-Acetylneuraminic Acid-Dependent Manner.
- 2014
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Ingår i: Infection and immunity. - 1098-5522. ; 82:12, s. 5235-45
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Tidskriftsartikel (refereegranskat)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.
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| 36. |
- Padra, János T, et al.
(författare)
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Aeromonas salmonicida Growth in Response to Atlantic Salmon Mucins Differs between Epithelial Sites, Is Governed by Sialylated and N-Acetylhexosamine-Containing O-Glycans, and Is Affected by Ca2
- 2017
-
Ingår i: Infection and Immunity. - : American Society for Microbiology. - 0019-9567 .- 1098-5522. ; 85:8
-
Tidskriftsartikel (refereegranskat)abstract
- Aeromonas salmonicida causes furunculosis in salmonids and is a threat to Atlantic salmon aquaculture. The epithelial surfaces that the pathogen colonizes are covered by a mucus layer predominantly comprised of secreted mucins. By using mass spectrometry to identify mucin glycan structures with and without enzymatic removal of glycan residues, coupled to measurements of bacterial growth, we show here that the complex Atlantic salmon intestinal mucin glycans enhance A. salmonicida growth, whereas the more simple skin mucin glycans do not. Of the glycan residues present terminally on the salmon mucins, only N-acetylglucosamine (GlcNAc) enhances growth. Sialic acids, which have an abundance of 75% among terminal glycans from skin and of <50% among intestinal glycans, cannot be removed or used by A. salmonicida for growth-enhancing purposes, and they shield internal GlcNAc from utilization. A Ca2+ concentration above 0.1 mM is needed for A. salmonicida to be able to utilize mucins for growth-promoting purposes, and 10 mM further enhances both A. salmonicida growth in response to mucins and binding of the bacterium to mucins. In conclusion, GlcNAc and sialic acids are important determinants of the A. salmonicida interaction with its host at the mucosal surface. Furthermore, since the mucin glycan repertoire affects pathogen growth, the glycan repertoire may be a factor to take into account during breeding and selection of strains for aquaculture.
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| 37. |
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| 38. |
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| 39. |
- Padra, János T, et al.
(författare)
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Atlantic Salmon Mucins Inhibit LuxS-Dependent A. Salmonicida AI-2 Quorum Sensing in an N-Acetylneuraminic Acid-Dependent Manner
- 2022
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 23:8
-
Tidskriftsartikel (refereegranskat)abstract
- One of the most important bacterial diseases in salmonid aquaculture is furunculosis, caused by Aeromonas salmonicida. Bacterial communication through secreted autoinducer signals, quorum sensing, takes part in the regulation of gene expression in bacteria, influencing growth and virulence. The skin and mucosal surfaces, covered by a mucus layer, are the first point of contact between fish and bacteria. Mucins are highly glycosylated and are the main components of mucus. Here, we validate the Vibrio harveyi BB170 bioreporter assay for quantifying A. salmonicida quorum sensing and study the effects of Atlantic salmon mucins as well as mono-and disaccharides on the AI-2 levels of A. salmonicida. Atlantic salmon mucins from skin, pyloric ceca, proximal and distal intestine reduced A. salmonicida AI-2 levels. Among the saccharides abundant on mucins, fucose, N-acetylneuraminic acid and GlcNAcβ1-3Gal inhibited AI-2 A. salmonicida secretion. Removal of N-acetylneuraminic acid, which is the most abundant terminal residue on mucin glycans on Atlantic salmon mucins, attenuated the inhibitory effects on AI-2 levels of A. salmonicida. Deletion of A. salmonicida luxS abolished AI-2 production. In conclusion, Atlantic salmon mucins regulate A. salmonicida quorum sensing in a luxS and N-acetylneuraminic acid-dependent manner.
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| 40. |
- Padra, János T, et al.
(författare)
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Fish pathogen binding to mucins from Atlantic salmon and Arctic char differs in avidity and specificity and is modulated by fluid velocity
- 2019
-
Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 14:5
-
Tidskriftsartikel (refereegranskat)abstract
- Disease outbreaks are limiting factors for an ethical and economically sustainable aquaculture industry. The first point of contact between a pathogen and a host occurs in the mucus, which covers the epithelial surfaces of the skin, gills and gastrointestinal tract. Increased knowledge on host-pathogen interactions at these primary barriers may contribute to development of disease prevention strategies. The mucus layer is built of highly glycosylated mucins, and mucin glycosylation differs between these epithelial sites. We have previously shown that A. salmonicida binds to Atlantic salmon mucins. Here we demonstrate binding of four additional bacteria, A. hydrophila, V. harveyi, M. viscosa and Y. ruckeri, to mucins from Atlantic salmon and Arctic char. No specific binding could be observed for V. salmonicida to any of the mucin groups. Mucin binding avidity was highest for A. hydrophila and A. salmonicida, followed by V. harveyi, M. viscosa and Y. ruckeri in decreasing order. Four of the pathogens showed highest binding to either gills or intestinal mucins, whereas none of the pathogens had preference for binding to skin mucins. Fluid velocity enhanced binding of intestinal mucins to A. hydrophila and A. salmonicida at 1.5 and 2 cm/s, whereas a velocity of 2 cm/s for skin mucins increased binding of A. salmonicida and decreased binding of A. hydrophila. Binding avidity, specificity and the effect of fluid velocity on binding thus differ between salmonid pathogens and with mucin origin. The results are in line with a model where the short skin mucin glycans contribute to contact with pathogens whereas pathogen binding to mucins with complex glycans aid the removal of pathogens from internal epithelial surfaces.
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| 41. |
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| 42. |
- Ringø, Einar, et al.
(författare)
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Damaging effect of the fish pathogen Aeromonas salmonicida ssp salmonicida on intestinal enterocytes of Atlantic salmon (Salmo salar L.)
- 2004
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Ingår i: Cell and Tissue Research. - : Springer Science and Business Media LLC. - 0302-766X .- 1432-0878. ; 318:2, s. 305-312
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Tidskriftsartikel (refereegranskat)abstract
- In fish, bacterial pathogens can enter the host by one or more of three different routes: (a) skin, (b) gills and (c) gastrointestinal tract. Bacteria can cross the gastrointestinal lining in three different ways. In undamaged tissue, bacteria can translocate by transcellular or paracellular routes. Alternatively, bacteria can damage the intestinal lining with extracellular enzymes or toxins before entering. Using an in vitro (Ussing chamber) model, this paper describes intestinal cell damage in Atlantic salmon (Salmo salar L.) caused by the fish pathogen Aeromonas salmonicida ssp. salmonicida, the causative agent of furunculosis. The in vitro method clearly demonstrated substantial detachment of enterocytes from anterior region of the intestine (foregut) upon exposure to the pathogen. In the hindgut (posterior part of the intestine), little detachment was observed but cellular damage involved microvilli, desmosomes and tight junctions. Based on these findings, we suggest that A. salmonicida may obtain entry to the fish by seriously damaging the intestinal lining. Translocation of bacteria through the foregut (rather than the hindgut) is a more likely infection route for A. salmonicida infections in Atlantic salmon.
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| 43. |
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| 44. |
- Schneider, T, et al.
(författare)
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'EUROPART'. Airborne particles in the indoor environment. A European interdisciplinary review of scientific evidence on associations between exposure to particles in buildings and health effects
- 2003
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Ingår i: Indoor Air. - : Hindawi Limited. - 0905-6947. ; 13:1, s. 38-48
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Tidskriftsartikel (refereegranskat)abstract
- The relevance of particle mass, surface area or number concentration as risk indicators for health effects in non-industrial buildings has been assessed by a European interdisciplinary group of researchers (called EUROPART) by reviewing papers identified in Medline, Toxline, and OSH. Studies dealing with dermal effects or cancer or specifically addressing environmental tobacco smoke, house dust-mite, cockroach or animal allergens, microorganisms and pesticides were excluded. A total of 70 papers were reviewed, and eight were identified for the final review: Five experimental studies involving mainly healthy subjects, two cross-sectional office studies and one longitudinal study among elderly on cardiovascular effects. From most studies, no definite conclusions could be drawn. Overall, the group concluded that there is inadequate scientific evidence that airborne, indoor particulate mass or number concentrations can be used as generally applicable risk indicators of health effects in non-industrial buildings and consequently that there is inadequate scientific evidence for establishing limit values or guidelines for particulate mass or number concentrations.
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| 45. |
- Sikora, M., et al.
(författare)
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The population history of northeastern Siberia since the Pleistocene
- 2019
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 570:7760
-
Tidskriftsartikel (refereegranskat)abstract
- Northeastern Siberia has been inhabited by humans for more than 40,000 years but its deep population history remains poorly understood. Here we investigate the late Pleistocene population history of northeastern Siberia through analyses of 34 newly recovered ancient genomes that date to between 31,000 and 600 years ago. We document complex population dynamics during this period, including at least three major migration events: an initial peopling by a previously unknown Palaeolithic population of 'Ancient North Siberians' who are distantly related to early West Eurasian hunter-gatherers; the arrival of East Asian-related peoples, which gave rise to 'Ancient Palaeo-Siberians' who are closely related to contemporary communities from far-northeastern Siberia (such as the Koryaks), as well as Native Americans; and a Holocene migration of other East Asian-related peoples, who we name 'Neo-Siberians', and from whom many contemporary Siberians are descended. Each of these population expansions largely replaced the earlier inhabitants, and ultimately generated the mosaic genetic make-up of contemporary peoples who inhabit a vast area across northern Eurasia and the Americas.
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| 46. |
- Stiller, Krystyna Marta, 1947, et al.
(författare)
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Atom probe tomography of oxide scales
- 2013
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Ingår i: Oxidation of Metals. - : Springer Science and Business Media LLC. - 1573-4889 .- 0030-770X. ; 79:3-4, s. 227-238
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Tidskriftsartikel (refereegranskat)abstract
- Atom probe tomography, APT, is the only microstructural method that can routinely analyse and position individual atoms in a material with a spatial resolution of 0.1-0.5 nm. Recent implementation of pulsed-laser to APT made investigation of less conducting materials, such as oxides, feasible. In this paper a short description of the principle of the techniques is presented, followed by examples of recent APT studies of thermally grown oxide scales produced on alumina formers (Pt-modified NiAl diffusion coating and FeCrAl alloy), at the crack tips in a Ni-based alloy and on a Zr-alloy. Additionally, results from preliminary studies of ZnO and MgO bulk materials are shown. The obtained information on the atomic scale about the chemistry variations in the scales and at the metal oxide interfaces provides valuable insights into oxidation processes. © 2012 Springer Science+Business Media New York.
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| 47. |
- Sundell, Kristina, 1959, et al.
(författare)
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Intestinal transport mechanisms and plasma cortisol levels during normal and out-of-season parr–smolt transformation of Atlantic salmon, Salmo salar
- 2003
-
Ingår i: Aquaculture. - 0044-8486. ; 222:1-4, s. 265-285
-
Tidskriftsartikel (refereegranskat)abstract
- The intestine is one of the major osmoregulatory organs in fish. During the salmon parr–smolt transformation, the intestine must change its functions from the freshwater (FW) role of preventing water inflow, to the seawater (SW) role of actively absorbing ions and water. This development can be assessed as an increased intestinal fluid transport (Jv) during the parr–smolt transformation. The developmental changes taking place during parr–smolt transformation are governed by a number of endocrine systems, of which cortisol is the main stimulator of Jv. In order to further elucidate the mechanisms behind the elevation of Jv during parr–smolt transformation, juvenile Atlantic salmon were followed during natural (1+age) as well as photoperiod-induced (0+age) smoltification. Plasma cortisol levels, gill and intestinal Na+,K+-ATPase activity, Jv (only during natural smoltification) and intestinal paracellular permeability were measured. In natural smolting as well as in photoperiod-induced smolting, normal patterns of plasma cortisol levels and gill Na+,K+-ATPase activity, with clearly defined, transient peaks were obtained. When fish were transferred to SW, a second elevation in plasma cortisol levels and gill Na+,K+-ATPase activity occurred, whereas Jv remained at similar levels as in FW fish. As to the mechanisms behind the increased Jv during parr–smolt transformation, the intestinal Na+,K+-ATPase activity increases in the anterior intestine and the paracellular permeability, as judged by transepithelial resistance (TER), appears to decrease in the posterior intestine. These events correspond with the increase in Jv seen during this developmental stage. Furthermore, the increase in the physiological parameters follows the changes in plasma cortisol levels, shifted by a couple of weeks. When the fish were transferred to SW, a further increase in Na+,K+-ATPase activity was apparent in both anterior and posterior intestine and the paracellular permeability decreases. To summarize, the increased Jv seen during the parr–smolt transformation of Atlantic salmon may be due to an increase in the paracellular water flow of the posterior intestine. When the fish enter SW, the water flow appears to be directed from the paracellular pathway towards a more transcellular route with increased intestinal Na+,K+-ATPase activity as the main driving force.
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| 48. |
- Sundell, Nicklas, et al.
(författare)
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Measles outbreak in Gothenburg urban area, Sweden, 2017 to 2018: low viral load in breakthrough infections
- 2019
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Ingår i: Eurosurveillance. - 1560-7917. ; 24:17, s. 2-12
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Tidskriftsartikel (refereegranskat)abstract
- In an outbreak of measles in Gothenburg, Sweden, breakthrough infections (i.e. infections in individuals with a history of vaccination) were common. The objective of this study was to compare measles RNA levels between naive (i.e. primary) and breakthrough infections. We also propose a fast provisional classification of breakthrough infections. Medical records were reviewed and real-time PCR-positive samples geno-typed. Cases were classified as naive, break-through or vaccine infections. We compared clinical symptoms and measles RNA cycle threshold (Ct) values between breakthrough and naive infections. Sixteen of 28 confirmed cases of measles in this outbreak were breakthrough infections. A fast provisional classification, based on previous history of measles vaccination and detectable levels of measles IgG in acute serum, correctly identified 14 of the 16 breakthrough infections, confirmed by IgG avidity testing. Measles viral load was significantly lower in nasopharyngeal samples from individuals with breakthrough compared with naive infections (median Ct-values: 32 and 19, respectively, p < 0.0001). No onward transmission from break-through infections was identified. Our results indicate that a high risk of onward transmission is limited to naive infections. We propose a fast provisional classification of breakthrough measles that can guide contact tracing in outbreak settings.
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| 49. |
- Sundh, Henrik, 1976, et al.
(författare)
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Development of intestinal ion-transporting mechanisms during smoltification and seawater acclimation in Atlantic salmon Salmo salar
- 2014
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Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112. ; 85:4, s. 1227-1252
-
Tidskriftsartikel (refereegranskat)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.
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| 50. |
- Sundh, Henrik, 1976, et al.
(författare)
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Reduced water quality associated with higher stocking density disturbs the intestinal barrier functions of Atlantic salmon (Salmo salar L.)
- 2019
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Ingår i: Aquaculture. - : Elsevier BV. - 0044-8486. ; 512
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Tidskriftsartikel (refereegranskat)abstract
- The stocking density of fish in aquaculture is of major importance as it may have profound effects on water quality resulting in impact on fish health and possibly affect the external barriers that protect against pathogens There are many husbandry conditions, including stocking density, that may affect the primary protective barriers, i.e. the skin, intestine and gills, against invading pathogens and other harmful substances. It is well known that increased fish density will lead to decreased dissolved oxygen (DO) levels and affect other water quality parameters such as carbon dioxide, pH and ammonia. It is not known if such changes in the rearing environment affect the intestinal primary barriers of Atlantic salmon. Groups of Atlantic salmon post-smolts were kept for 57 days in tanks supplied with seawater at a constant flow at stocking densities of 10, 30, 50 and 70 kg m−3; reduced water quality was associated with higher stocking density. Repeated sampling for plasma cortisol and water cortisol release rate indicate that the highest stocking density elicited a primary stress response in the fish, which decreased with time. The physical intestinal barrier was assessed using paracellular permeability measurements, i.e. transepithelial electrical resistance (TER) and diffusion rate of 14C-mannitol, in combination with the translocation rate of heat-inactivated Aeromonas salmonicida. The physical intestinal barrier decreased with increasing density, both when measured as decreased transepithelial electrical resistance and as elevated paracellular permeability for 14C-mannitol. As this was observed at a time point when no differences could be seen in plasma cortisol or cortisol release rate, it suggests that intestinal paracellular permeability can be a useful marker for chronic stress in salmon. The status of the intestinal immune system was assessed as degree of neutrophil infiltration as well as the mRNA expression of the pro-inflammatory cytokines, interferon γ (IFNγ), interleukin (IL) 1β and tumor necrosis factor (TNF) α, anti-inflammatory cytokines, IL-10 and transforming growth factor β (TGFβ) and other immune related-genes, IL-8 and the inhibitor of the transcription factor nuclear factor κB (IκB). The intestinal immune system was affected at the highest stocking density as observed by a decreased expression of IFNγ in parallel with higher infiltration of neutrophils. In conclusion, high stocking density associated with reduced water quality is chronically stressful to the fish as it elicits a primary stress response as well as a weakened physical and disturbed immunological primary barrier.
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