Welfare effects of environmental hypercapnia quantified by indicators based on morphology and allostatic load in Atlantic salmon (Salmo salar)

Water supply is a limited resource in most salmon hatcheries, which is compensated by reduced water flow and oxygenation. However, reduced water exchange can lead to accumulation of CO2, resulting in environmental hypercapnia, which may have negative impacts on fish welfare. Thus, environmental hypercapnia can be a common welfare problem for salmon in hatcheries, and particularly in recirculating systems (RAS). In this experiment, Atlantic salmon were exposed to chronic environmental hypercapnia during the last 68 days of the freshwater phase, whereupon effects on physiological stress coping mechanisms and morphological welfare indicators were investigated. Effects on stress coping mechanisms were quantified by measuring changes in brain serotonergic chemistry and plasma cortisol at basal levels and in response to a standardized acute stress test. The results show that exposure to elevated CO2 saturation in the water compromised stress responsiveness of brainstem serotonergic activity, altered osmotic homeostasis, and suppressed growth indicating that fish experience allostatic overload. However, no effects on morphological welfare indicators were observed. This accentuates the need for physiological measures, including physiological responses to controlled challenges to activate the stress axis, when investigating the welfare status of fish reared in systems with potential high CO2.publishedVersio

Velferdsindikatorer for oppdrettslaks: Hvordan vurdere og dokumentere fiskevelferd - Del A. fiskevelferd og oppdrettslaks, kunnskap og teoretisk bakgrunn

publishedVersio

Decellularized Matrix from Tumorigenic Human Mesenchymal Stem Cells Promotes Neovascularization with Galectin-1 Dependent Endothelial Interaction

BACKGROUND: Acquisition of a blood supply is fundamental for extensive tumor growth. We recently described vascular heterogeneity in tumours derived from cell clones of a human mesenchymal stem cell (hMSC) strain (hMSC-TERT20) immortalized by retroviral vector mediated human telomerase (hTERT) gene expression. Histological analysis showed that cells of the most vascularized tumorigenic clone, -BD11 had a pericyte-like alpha smooth muscle actin (ASMA+) and CD146+ positive phenotype. Upon serum withdrawal in culture, -BD11 cells formed cord-like structures mimicking capillary morphogenesis. In contrast, cells of the poorly tumorigenic clone, -BC8 did not stain for ASMA, tumours were less vascularized and serum withdrawal in culture led to cell death. By exploring the heterogeneity in hMSC-TERT20 clones we aimed to understand molecular mechanisms by which mesenchymal stem cells may promote neovascularization. METHODOLOGY/PRINCIPAL FINDINGS: Quantitative qRT-PCR analysis revealed similar mRNA levels for genes encoding the angiogenic cytokines VEGF and Angiopoietin-1 in both clones. However, clone-BD11 produced a denser extracellular matrix that supported stable ex vivo capillary morphogenesis of human endothelial cells and promoted in vivo neovascularization. Proteomic characterization of the -BD11 decellularized matrix identified 50 extracellular angiogenic proteins, including galectin-1. siRNA knock down of galectin-1 expression abrogated the ex vivo interaction between decellularized -BD11 matrix and endothelial cells. More stable shRNA knock down of galectin-1 expression did not prevent -BD11 tumorigenesis, but greatly reduced endothelial migration into -BD11 cell xenografts. CONCLUSIONS: Decellularized hMSC matrix had significant angiogenic potential with at least 50 angiogenic cell surface and extracellular proteins, implicated in attracting endothelial cells, their adhesion and activation to form tubular structures. hMSC -BD11 surface galectin-1 expression was required to bring about matrix-endothelial interactions and for xenografted hMSC -BD11 cells to optimally recruit host vasculature

In Vivo Development of Quinolone Resistance in Salmonella enterica Serotype Typhimurium DT104

Salmonella enterica serotype Typhimurium definitive phage type 104 was isolated several times from the same patient over a period of 2 years. The strain developed reduced sensitivity to fluoroquinolones, and a mutation in the gyrA gene that is associated with reduced sensitivity to quinolones was identified

The metabolic rate response to feed withdrawal in Atlantic salmon post-smolts

Feed withdrawal is a widespread practice in Atlantic salmon (Salmo salar) aquaculture to empty the gut prior to major farming operations, while certain pathogens and suboptimal environmental conditions in production cages are known to induce prolonged fasting. However, these fasting periods may be in conflict with ethical and legal obligations to farm animals. Presently, science-based recommendations on responsible fasting times that consider fish welfare are lacking. In this study, we measured the standard metabolic rate (SMR) and metabolic rate following acute handling and confinement stress in Atlantic salmon post smolts (~575 g, ~38 cm) following 1, 2, 3 and 4 weeks of feed withdrawal and 1 week of subsequent refeeding at 12 °C. The purpose was to identify when changes in metabolic mode occurred and assess whether the capacity to respond to stress eventually was compromised, since such observations could serve as potential welfare indicators. The SMR decreased significantly from 84.4 ± 4.7 mg O2 kg h−1 in control fish to 71.0 ± 1.8 mg O2 kg h−1 following 1 week of fasting. A further significant decrease to 65.0 ± 3.7 mg O2 kg h−1 was measured after 3 weeks, while refeeding returned SMR to control levels. The increase in MO2 following acute stress was unaffected for the first three weeks of fasting. However, the 4 week group showed a reduced peak response compared to the preceding weeks (278 ± 13 vs. 310 ± 7 mg O2 kg h−1). Weight, fork length and condition factor did not change significantly during the fasting period, and the fish immediately resumed eating upon refeeding. We conclude that up to 4 weeks of feed withdrawal had negligible effects on fish welfare. Moreover, an improved aerobic scope owing to a reduced SMR may be advantageous prior to certain farm operations