Experimental challenge of Atlantic salmon Salmo salar using clones of Paramoeba perurans, P. pemaquidensis and Tetramitus sp.

Salmon gill disease in Norway is in most cases associated with a range of different pathogens, stress and environmental factors. Paramoeba perurans and other amoebae have been isolated during such disease outbreaks. Other amoebae isolated from salmon with gill disease in Norway include P. pemaquidensis, Tetramitus sp. and Vannella sp. Here we tested the pathogenicity of the first 2 species in challenge experiments. We found that even when clonal cultures of P. pemaquidensis established an infection on the gills of salmon, it failed to cause gill disease, while Tetramitus sp. appeared to be unable to establish a lasting infection on the gills of healthy salmon. The result of the challenge with P. pemaquidensis confirms the results of similar studies performed in the USA and in Australia. Tetramitus sp. is probably a common amoeba in the marine environment, and its presence on the gills of farmed salmon may just be accidental. Based on this study, we conclude that P. perurans is the only known amoeba in marine salmon farming associated with amoebic gill disease in Norway.publishedVersio

Mens vi venter på at Bitcoin skal ta over verden. Finnes det faktorer som kan forklare Bitcoins avkastning og handelsvolum?

Teamet for denne oppgaven er å undersøke forhold som påvirker avkastning og handelsvolum for kryptovalutaen Bitcoin. Vi forsøker å si noe om årsak og virkning i denne sammenhengen. Det er gjort liknende studier, men de fleste er to til fem år gamle, og kun et fåtall tar for seg årsak og virkning. Dersom en investor kjenner til om avkastningen og handelsvolum kan forklares av realøkonomiske variabler eller interesse kan forståelsen av Bitcoin bli bedre. Studiens problemstilling formuleres slik: Finnes det realøkonomiske faktorer som forklarer endringen i Bitcoins avkastning og handelsvolum over tid? For å svare på problemstillingen benyttes multippel regresjonsanalyse i kombinasjon med Grangers kausalitetstest for å redegjøre for signifikante forhold i modellen. Valg av variabler og analyse er forankret i litteratur på området. Innsamlingen av data ble sluttført i februar og resulterte i 1203 observasjoner av 10 variabler fra 2013 til 2018. Når statistiske tester er gjennomført og modellene analysert viser resultatene at Bitcoins avkastning ikke kan forklares med variablene i dette datasettet. De eneste tilfellene hvor vi kan forklare noe av variasjonen i Bitcoins avkastning er når analysen gjøres i årlige tidsintervaller. På grunn av en sterk sammenheng mellom interesse og handelsvolum klarer oppgaven å større grad å forklare variasjon i handelsvolum enn avkastning

Method for cryopreservation of Paramoeba perurans

Paramoeba perurans causes amoebic gill disease (AGD), which is a major problem in aquaculture worldwide. The parasite can be cultured in vitro, but to this date, no method for long-term storage of the clones exists. In this study, we describe a method for cryopreservation of Paramoeba perurans. The method was successfully employed on four out the five clones we tested. The thawing success rate, that is the percentage of successfully thawed vials relative to the total number of vials that were thawed, differed for the clones and ranged from 25% to 100%. The age of the clones seemed to have a negative impact on the ability to survive cryopreservation.publishedVersio

Atlantic salmon Salmo salar and ballan wrasse Labrus bergylta display different susceptibility to clonal strains of Paramoeba perurans

Amoebic gill disease (AGD), caused by the marine amoeba Paramoeba perurans, is an important disease of farmed Atlantic salmon Salmo salar L. in Norway. The use of wrasse as cleaner fish in salmon net pens raises questions about interspecies transmission of pathogens such as P. perurans. In this study, cohabitant transmission of clonal isolates of P. perurans between Atlantic salmon and ballan wrasse Labrus bergylta Ascanius was examined, using isolates originating from both salmon and wrasse. The challenges resulted in AGD in both species, although less severely in wrasse. The amoeba isolate originating from ballan wrasse was more virulent than that originating from salmon, suggesting P. perurans strain-related virulence differences. The isolate originating from salmon showed limited proliferation in bath-challenged wrasse and salmon, and limited transfer to cohabitants. Our results support previous observations suggesting that salmon may be more susceptible to P. perurans and AGD than ballan wrasse. Treatment of P. perurans infection in wrasse is challenging, as it is a strictly marine fish species. In this study, brackish water (<15‰ seawater) treatment of AGD affected salmon and wrasse was examined. Both salmon and wrasse were treated for short periods (3 h and 24 h), and treatment of wrasse over longer periods (3-5 d) was also examined. Short exposure to brackish water was not enough to remove P. perurans, although the 24 h treatment reduced amoeba levels. It was not possible to culture or detect P. perurans from wrasse exposed to brackish water for 3 d, suggesting that this treatment would be effective in controlling the parasite.publishedVersio

Peer support in small towns: A decentralized mobile Hepatitis C virus clinic for people who inject drugs

Background & aims: New models of HCV care are needed to reach people who inject drugs (PWID). The primary aim was to evaluate HCV treatment uptake among HCV RNA positive individuals identified by point-of-care (POC) testing and liver disease assessment in a peer-driven decentralized mobile clinic. Methods: This prospective study included consecutive patients assessed in a mobile clinic visiting 32 small towns in Southern Norway from November 2019 to November 2020. The clinic was staffed by a bus driver and a social educator offering POC HCV RNA testing (GeneXpert®), liver disease staging (FibroScan® 402) and peer support. Viremic individuals were offered prompt pan-genotypic treatment prescribed by local hospital-employed specialists following a brief telephone assessment. Results: Among 296 tested individuals, 102 (34%) were HCV RNA positive (median age 51 years, 77% male, 24% advanced liver fibrosis/cirrhosis). All participants had a history of injecting drug use, 71% reported past 3 months injecting, and 37% received opioid agonist treatment. Treatment uptake within 6 months following enrolment was achieved in 88%. Treatment uptake was negatively associated with recent injecting (aHR 0.60; 95% CI 0.36-0.98), harmful alcohol consumption (aHR 0.44; 95% CI 0.20-0.99), and advanced liver fibrosis/cirrhosis (aHR 0.44; 95% CI 0.25-0.80). HCV RNA prevalence increased with age (OR 1.81 per 10-year increase; 95% 1.41-2.32), ranging from 3% among those <30 years to 55% among those ≥60 years. Conclusions: A peer-driven mobile HCV clinic is an effective and feasible model of care that should be considered for broader implementation to reach PWID outside the urban centres. Keywords: hepatitis C virus; peer support; people who inject drugs; point of care; treatment. © 2022 The Authors. Liver International published by John Wiley & Sons Ltd.publishedVersio

A combined rocket-borne and ground-based study of the sodium layer and charged dust in the upper mesosphere

The Hotel Payload 2 rocket was launched on January 31st 2008 at 20.14 LT from the Andøya Rocket Range in northern Norway (69.31° N, 16.01° E). Measurements in the 75–105 km region of atomic O, negatively-charged dust, positive ions and electrons with a suite of instruments on the payload were complemented by lidar measurements of atomic Na and temperature from the nearby ALOMAR observatory. The payload passed within 2.58 km of the lidar at an altitude of 90 km. A series of coupled models is used to explore the observations, leading to two significant conclusions. First, the atomic Na layer and the vertical profiles of negatively-charged dust (assumed to be meteoric smoke particles), electrons and positive ions, can be modelled using a self-consistent meteoric input flux. Second, electronic structure calculations and Rice–Ramsperger–Kassel–Markus theory are used to show that even small Fe–Mg–silicates are able to attach electrons rapidly and form stable negatively-charged particles, compared with electron attachment to O2 and O3. This explains the substantial electron depletion between 80 and 90 km, where the presence of atomic O at concentrations in excess of 1010 cm−3 prevents the formation of stable negative ions

Mitochondrial physiology

As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery

Mitochondrial physiology

As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery

The Barents and Chukchi Seas: Comparison of two Arctic shelf ecosystems

This paper compares and contrasts the ecosystems of the Barents and Chukchi Seas. Despite their similarity in a number of features, the Barents Sea supports a vast biomass of commercially important fish, but the Chukchi does not. Here we examine a number of aspects of these two seas to ascertain how they are similar and how they differ. We then indentify processes and mechanisms that may be responsible for their similarities and differences.Both the Barents and Chukchi Seas are high latitude, seasonally ice covered, Arctic shelf-seas. Both have strongly advective regimes, and receive water from the south. Water entering the Barents comes from the deep, ice-free and "warm" Norwegian Sea, and contains not only heat, but also a rich supply of zooplankton that supports larval fish in spring. In contrast, Bering Sea water entering the Chukchi in spring and early summer is cold. In spring, this Bering Sea water is depleted of large, lipid-rich zooplankton, thus likely resulting in a relatively low availability of zooplankton for fish. Although primary production on average is similar in the two seas, fish biomass density is an order of magnitude greater in the Barents than in the Chukchi Sea. The Barents Sea supports immense fisheries, whereas the Chukchi Sea does not. The density of cetaceans in the Barents Sea is about double that in the Chukchi Sea, as is the density of nesting seabirds, whereas, the density of pinnipeds in the Chukchi is about double that in the Barents Sea. In the Chukchi Sea, export of carbon to the benthos and benthic biomass may be greater. We hypothesize that the difference in fish abundance in the two seas is driven by differences in the heat and plankton advected into them, and the amount of primary production consumed in the upper water column. However, we suggest that the critical difference between the Chukchi and Barents Seas is the pre-cooled water entering the Chukchi Sea from the south. This cold water, and the winter mixing of the Chukchi Sea as it becomes ice covered, result in water temperatures below the physiological limits of the commercially valuable fish that thrive in the southeastern Bering Sea. If climate change warms the Barents Sea, thereby increasing the open water area via reducing ice cover, productivity at most trophic levels is likely to increase. In the Chukchi, warming should also reduce sea ice cover, permitting a longer production season. However, the shallow northern Bering and Chukchi Seas are expected to continue to be ice-covered in winter, so water there will continue to be cold in winter and spring, and is likely to continue to be a barrier to the movement of temperate fish into the Chukchi Sea. Thus, it is unlikely that large populations of boreal fish species will become established in this Arctic marginal sea. © 2012 Elsevier B.V