The effect of dietary lipid on polyunsaturated fatty acid metabolism in Atlantic salmon (Salmo salar) undergoing parr-smolt transformation.

The aim of this study was to measure the changes in lipid metabolism which occur during smoltification and seawater transfer in Atlantic salmon (Salmo salar). Duplicate groups of Atlantic salmon parr were fed diets containing either fish oil (FO) or a blend of linseed and rapeseed oils, vegetable oil (VO), from October (week 0) to seawater transfer in May (week 26). From May to August (weeks 26-43), all fish were fed a fish oil-containing diet. Fatty acyl desaturation and elongation activity were followed in isolated hepatocytes incubated with radioactive 18:3n-3 and 18:2n-6. Metabolism of 18:3n-3 was consistently around 5-fold greater than metabolism of 18:2n-6, and total metabolism of both substrate polyunsaturated fatty acids (PUFA) was increased in fish fed both VO and FO up to seawater transfer after which desaturation activities were reduced. Desaturation activities with both 18:3n-3 and 18:2n-6 were significantly greater in fish fed VO, compared to fish fed FO, at 22 and 26 wk. Arachidonic acid (20:4n-6; AA) in liver polar lipids (PL) of fish fed VO increased consistently from weeks 0-22 but varied after seawater transfer. In fish fed FO, AA in liver PL remained constant up to week 17 before increasing at seawater transfer and leveling off thereafter. Eicosapentaenoic acid (20:5n-3; EPA) in liver PL of fish fed VO decreased significantly from week 0-22 before rising at seawater transfer and increasing rapidly posttransfer. EPA in liver PL of fish fed FO showed a similar trend except EPA was always greater in the freshwater phase compared to fish fed VO. Docosahexaenoic acid (DHA) levels in liver PL of fish fed VO remained constant in the seawater phase before increasing following seawater transfer. In fish fed FO, DHA in liver PL increased from weeks 0-17 reducing and leveling off postseawater transfer. The levels of PGF(2 alpha) and PGF(3 alpha) were measured in isolated gill cells stimulated with calcium ionophore A23187. PGF(2 alpha) production in fish fed VO increased significantly between 0-7 wk before decreasing toward seawater transfer. After transfer, PGF(2 alpha), production increased to a peak at 35 wk. PGF(2 alpha) production in fish fed FO was not significantly altered during the trial period. The changes in PGF(3 alpha) production were broadly similar to those occurring with PGF(2 alpha), but the latter was always in excess of the former (2- to 4-fold). Plasma chloride concentrations in fish subjected to seawater challenge at 20 wk were significantly lower in fish fed VO compared to those fed FO. This study has provided new information on the changes in lipid metabolism which accompany parr-smolt transformation and suggests that diets which have a fatty acid composition more similar to that in aquatic invertebrates may be beneficial in effecting successful seawater adaptation.

Use of hamsters of potency assay of Eastern and Western equine encephalitis vaccines.

An antigen extinction test in hamsters is described. Comparative potency assays with guinea pigs and hamsters showed the latter to be a suitable, advantageous replacement animal in these assays.

Cross-protection in hamsters immunized with group A arbovirus vaccines.

Cross-protection between Venezuelan, Eastern, and Western equine encephalomyelitis (VEE, EEE, WEE) viruses was studied in the hamster by using challenge responses and neutralizing antibody titers as indexes of protection. Formalin-inactivated vaccines induced only homologous protection regardless of the sequence of vaccination or the combination of vaccines employed. Use of attenuated VEE vaccine, singly, produced absolute homologous protection as well as 37 and 59% protection against WEE and EEE challenges, respectively. Neither deleterious nor enhancing interaction occurred when attenuated VEE and inactivated WEE and EEE vaccines were employed in various sequences of immunization and all possible combinations. The most rapid and simple immunization scheme eliciting excellent homologous protection consisted of a single dose of combined attenuated VEE and inactivated WEE and EEE vaccines. Studies with attenuated strains of VEE, EEE, and WEE viruses showed that all elicited excellent homologous protection when administered singly. However, use of these live strains in many combinations and sequences resulted in a significant (P < 0.05 to <0.001) decrease in the protective efficacy of the WEE or EEE strains. These results are discussed in relation to serum neutralization test data obtained on sera drawn pre- and postchallenge.

Capture your market share. Healthcare's largest growth area requires strategic facilities planning.

The outpatient consumer has more choices than ever before. Hospital's delivery systems must be optimized to remain competitive and survive financially.

Rapid detection of viral antibody by cellulose acetate electrophoresis.

An immunoelectrophoretic procedure utilizing microprecipitation and cellulose acetate electrophoresis was developed for detection of antibody to specific virus. A model system of tobacco mosaic virus and homologous rabbit antiserum is described.

Guidelines for the prevention of simian immunodeficiency virus infection in laboratory workers and animal handlers.

The authors are members of a working group that formulated guidelines to minimize transmission of simian immunodeficiency virus (SIV) infection to man. Biosafety level (BSL) 2 standards are recommended for handling of clinical specimens and housing of SIV inoculated animals. Manipulation of SIV preparations may be performed in a BSL 2 facility with additional BSL 3 practices and equipment; for large volume or concentrated preparations of SIV BSL 3 containment is necessary. Written policies regarding management and testing of workers exposed to SIV are recommended.