Protective effects of a DNA vaccine expressing the infectious salmon anemia virus hemagglutinin-esterase in Atlantic salmon

Infectious salmon anemia (ISA) is a disease, caused by an orthomyxovirus, which has considerable economic impact on farming of Atlantic salmon. Here we describe the results of immunization against ISA using plasmids expressing the ISA virus hemagglutinin-esterase (HE). Immunized Atlantic salmon demonstrated moderate protection after challenge with ISA virus, with relative percent survival of 39.5 and 60.5 in two parallel groups. No protection was seen after immunization using a plasmid expressing the ISA virus nucleoprotein. Fish in the HE-immunized group had earlier onset of clearance of the virus than control fish. There was no detectable ISA virus specific humoral response after immunization. After challenge a specific humoral response could be demonstrated in the fish in all groups, but no correlation between this response and protection was found.     

Expression,antigenicity and studies on cell receptor binding of the hemagglutinin of infectious salmon anemia virus

Summary. Infectious salmon anemia (ISA) virus belongs to the proposed genus Isavirus of Orthomyxoviridae and is an emerging pathogen in Atlantic salmon (Salmo salar) farming. The hemagglutinin-esterase (HE) of ISA virus share several characteristics with the influenza virus hemagglutinin. This study reports recombinant expression of different ISA virus HE mutants in fish cell lines. Some introduced mutations, representing minimal differences in single amino acid residues, resulted in remarkable effects on expression efficiency in general and on surface expression specifically. Receptor binding assays showed that amino acid residues in the N-terminal half part are important in receptor binding, either being directly involved in the binding, or by influencing the structure of the binding site. Deletion of the putative N-glycosylation sites of the ISA virus HE, located near the transmembrane region, did not influence expression, receptor binding properties or staining by either a neutralising MAb, or salmon convalescent sera. The humoral immune response of Atlantic salmon after ISA virus infection showed weak neutralising activity and the results indicated that it was directed against HE.     

Notochord segmentation may lay down the pathway for the development of the vertebral bodies in the Atlantic salmon

This study indicates that the development of the vertebrae in the Atlantic salmon requires the orchestration of two sources of metameric patterning, derived from the notochord and the somite rows, respectively. Before segmentation of the salmon notochord, chordoblasts exhibit a well-defined cell axis that is uniformly aligned with the cranio-caudal axis. The morphology of these cells is characterised by a foot-like basal projection that rests on the notochordal sheath. Notochordal segments are initially formed within the chordoblast layer by metameric change in the axial orientation of groups of chordoblasts. This process results in the formation of circular bands of chordoblasts, with feet perpendicular to the cranio-caudal axis, the original chordoblast orientation. Each vertebra is defined by two such chordoblast bands, at the cranial and caudal borders, respectively. Formation of the chordoblast segments closely precedes formation of the chordacentra, which form as calcified rings within the adjacent notochordal sheath. Sclerotomal osteoblasts then differentiate on the surface of the chordacentra, using them as foundations for further vertebral growth. Thus, the morphogenesis of the rudiments of the vertebral bodies is initiated by a generation of segments within the chordoblast layer. This dual segmentation model for salmon, in which the segmental patterns of the neural and haemal arches are somite-derived, while the vertebral segments seem to be notochord-derived, contrasts with current models for avians and mammals.     

Stress in obesity: cause or consequence?

Obesity is a global public health challenge that increases the risk of various diseases including type 2 diabetes mellitus, hypertension and cancer, and will in the future cause further increases in the incidence of chronic disease. Understanding the mechanisms of obesity is critical if we are to prevent and treat this pandemic challenge. Diet and physical activity have traditionally been the major tasks in preventing and treating obesity. However, other mechanisms are now also being considered in the quest for knowledge and understanding of obesity, including the body’s stress system and cortisol release. While it seems evident that stress is a cause of obesity, whether stress is also a consequence of obesity has up to now only briefly been discussed. The aim of this article is to elucidate how stress and obesity might be linked and discuss the cause/consequence relationship between the stress response and obesity. Our hypothesis is that stress and obesity interfere by positive feedback. This may be an important issue in both our understanding and coping of obesity.     

Sustained swimming increases the mineral content and osteocyte density of salmon vertebral bone

This study addresses the effects of increased mechanical load on the vertebral bone of post-smolt Atlantic salmon by forcing them to swim at controlled speeds. The fish swam continuously in four circular tanks for 9 weeks, two groups at 0.47 body lengths (bl) × s(-1) (non-exercised group) and two groups at 2 bl × s(-1) (exercised group), which is just below the limit for maximum sustained swimming speed in this species. Qualitative data concerning the vertebral structure were obtained from histology and electron microscopy, and quantitative data were based on histomorphometry, high-resolution X-ray micro-computed tomography images and analysis of bone mineral content, while the mechanical properties were tested by compression. Our key findings are that the bone matrix secreted during sustained swimming had significantly higher mineral content and mechanical strength, while no effect was detected on bone in vivo architecture. mRNA levels for two mineralization-related genes bgp and alp were significantly upregulated in the exercised fish, indicating promotion of mineralization. The osteocyte density of the lamellar bone of the amphicoel was also significantly higher in the exercised than non-exercised fish, while the osteocyte density in the cancellous bone was similar in the two groups. The vertebral osteocytes did not form a functional syncytium, which shows that salmon vertebral bone responds to mechanical loading in the absence of an extensive connecting syncytial network of osteocytic cell processes as found in mammals, indicating the existence of a different mechanosensing mechanism. The adaptive response to increased load is thus probably mediated by osteoblasts or bone lining cells, a system in which signal detection and response may be co-located. This study offers new insight into the teleost bone biology, and may have implications for maintaining acceptable welfare for farmed salmon.     

Intra-individual stability of CSF biomarkers for Alzheimer's disease over two years

This study examines the intra-individual stability of cerebrospinal fluid (CSF) biomarkers for Alzheimer's disease (AD) over 2 years in 83 patients with mild cognitive impairment (MCI) and 17 cognitively healthy control individuals. All participants underwent clinical and neuropsychological evaluation and lumbar puncture at baseline and after 2 years at a university hospital memory clinic. CSF was analyzed for total tau (T-tau), phospho-tau(181) (P-tau(181)) and amyloid-beta(1-42) (Abeta(1-42)). During the 2-year observational time, 12 MCI patients progressed to AD and 3 progressed to vascular dementia, while 68 remained stable. Baseline T-tau and P-tau(181) levels were elevated in the MCI-AD group as compared to the stable MCI patients and the control group (p<0.01), while baseline Abeta(1-42) levels were lower (p<0.001). Stable MCI patients were biochemically indistinguishable from controls. The biomarker levels at baseline and after 2 years showed Pearson R values between 0.81 and 0.91 (p<0.001) and coefficients of variation of 7.2 to 8.7%. In conclusion, intra-individual biomarker levels are remarkably stable over 2 years. Thus, even minor biochemical changes induced by treatment against AD should be detectable using these biomarkers, which bodes well for their usefulness as surrogate markers for drug efficacy in clinical trials.     

Physical fitness, training volume, and self-determined motivation in soldiers during a peacekeeping mission

PURPOSE: The goal was to register physical training volume and to measure changes in physical fitness in soldiers during a peacekeeping mission. The relationship between these factors and motivation for physical training was also investigated. METHODS: Physical training volume was registered and maximal oxygen uptake, 3-km run time, sit-ups, push-ups, and chin-ups were tested before and after 1 year of service for 71 Norwegian soldiers in the international Kosovo Force. Self-determined motivation was measured at the end of the service. RESULTS: Physical training volume was 117 +/- 77 minutes/week. The average maximal oxygen uptake decreased by 2.5 +/- 0.8% (p < 0.01). Intrinsic motivation positively predicted physical training volume (p < 0.01). CONCLUSIONS: A large variation in training volume was found, and only one-third of the soldiers improved physical fitness and maintained body weight. Fostering intrinsic motivation toward physical training is key to increasing training volume. However, obligatory training could ensure a minimum of physical training among the soldiers who were least motivated for physical training.