Lack of evidence for vertical transmission of SAV 3 using gametes of Atlantic salmon, Salmo salar L., exposed by natural and experimental routes

Pancreas disease (PD) is an important cause of losses in farmed salmonids in Norway, the United Kingdom and Ireland. As the spread of salmonid alphavirus (SAV), the causal agent, to naïve populations is of major concern to the farming industry, it is important to uncover the transmission routes of the virus. This study was conducted to investigate the potential for vertical transmission of SAV subtype 3. Progeny of broodstock with signs of late‐stage PD and persistent RT‐PCR signals for SAV were followed from fertilization to smoltification in an experimental facility. Fertilized ova were either not disinfected or taken through one of three different disinfection regimes. Also, ova and milt from uninfected broodfish from a different population were exposed to a cell‐cultured strain of SAV 3 immediately before fertilization to simulate a viraemic phase in parent fish. A group of uninfected controls were also included in the study. Fertilized ova from bath exposed and negative control groups were double disinfected. Following fertilization, experimental fish went through a normal freshwater phase. However, fry were stressed at first feeding to enhance replication of possibly latent virus. Smoltification was induced by an artificial light regime, and experimental fish were followed to the late smoltification phase. Selected samples were investigated by real‐time RT‐PCR for SAV, by histology for evidence of PD and by serology for neutralising antibodies against SAV. All analysed samples of progeny were negative. This result shows that SAV 3 is not readily transmitted vertically from parents to offspring. Additional negative PCR results from salmon sampled in commercial hatcheries support these findings. Also, recent studies have shown that risk factors for the horizontal transmission route explain the vast majority of PD outbreaks in Norway. It is concluded that if it happens at all, vertical transmission is of minor importance in the spread of SAV 3.     

Consumer Demand for Low-Acrylamide-Forming Potato Products: Evidence from Lab Auctions

A probable human carcinogen—acrylamide—was discovered about a decade ago to form naturally in potato products cooked at high temperatures. Using incentive compatible lab auctions and adult consumers from three distant U.S. locations, we test food labeling and information effects on willingness-to-pay (WTP) for conventional and genetically engineered potatoes, fries, and chips to reduce acrylamide levels. These new potato products are the first biotech products to have enhanced food safety for a popular food in the American and European diets. Relative to an environmental group’s perspective, scientific and industry information significantly increase WTP for biotech relative to conventional potato products. In addition, we find significant location-specific fixed effects of information treatments. Scientific and industry information can be used to nudge consumers towards improved decision making and healthy diets.     

Field trials with trimethoprim and sulphadoxine

Extract

Sir, — Trimethoprim (2,4-diamino-5-(3,4,5,trimethoxy-benzyl) pyrimidine) is an inhibitor of the enzyme dihydrofolate reductase and blocks its action in bacterial cell metabolism. Sulphonamides act similarly on a different enzyme and, when the two are used in combination, clinical results are much enhanced and a synergistic effect has been shown in vitro.     

Patterns of cover crop use,adoption, and impacts among Indiana farmers

Cover crops have recently been generating a lot of interest in agriculture for their agronomic benefits, including erosion control, nutrient restoration, and increased cash crop yield. However, the value of these benefits is not well established and likely highly variable. The factors that influence a farmer’s decision to adopt or not adopt cover crops are also a point of interest to conservationists and policy makers. As part of a long-term study estimating the benefits and costs of cover crops, this study analyzed five years of historic information collected from Indiana farmers, who either grew or did not grow cover crops. No significant impact was found from cover crops on cash crop yields, but several interesting correlations in cover crop use were found. Cover crop use was higher on steeper fields. There was also a high correlation between the use of cover crops and no-till.