USGS · 1014544
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E. B. Shotts, G. L. Bullock. 1976. Rapid diagnostic approaches in the identification of gram-negative bacterial diseases of fish. https://doi.org/10.3147/jsfp.10.187
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Mortalities of yellowtail Seriola quinqueradiata artificially infected with Lactococcus garvieae and of rainbow trout Oncorhynchus mykiss artificially infected with Vibrio anguillarum were compared with the levels of plasma components measured prior to challenge. The levels of plasma total cholesterol, free cholesterol and phospholipid of fish surviving infection were significantly higher in both yellowtail and rainbow trout than those of fish which died during the challenge test. Mortality of yellowtail with plasma total cholesterol levels lower than 250 mg/100 ml was significantly higher than that of fish which had cholesterol levels higher than 275 mg/100 ml (p < 0.05). Rainbow trout whose cholesterol was lower than 520 mg/100 ml suffered a significantly higher mortality due to vibriosis than fish having cholesterol levels higher than 560 mg/100 ml (p < 0.005). These results indicate that low levels of plasma lipid components may be an indicator of lowered disease resistance in cultured fish.
Genomic RNA was extracted from purified virions of hirame rhabdovirus (HRV), infectious hematopoietic necrosis virus (IHNV), and viral hemorrhagic septicemia virus (VHSV). The full-length RNA was analyzed using formaldehyde agarose gel electrophoresis followed by ethidium bromide staining. Compared with an internal RNA size standard, all three viral genomic RNAs appeared to have identical relative mobilities and were estimated to be approximately 10.7 kilobases in length or about 3.7 megadaltons in molecular mass. Structural protein synthesis of HRV, IHNV, and VHSV was studied using cell cultures treated with actinomycin D. At 2 h intervals, proteins were labeled with 35 S-methionine, extracted, and analyzed by SDS-polyacrylamide gel electrophoresis and autoradiography. The five structural proteins of each of the three viruses appeared in the following order : nucleoprotein (N), matrix protein 1 (M1), matrix protein 2 (M2), glycoprotein (G), and polymerase (L) reflecting both the approximate relative abundance of each protein within infected cells and the gene order within the viral genome.
A cell line from rainbow trout ( Oncorhynchus mykiss ) with phagocytic-like characteristics was established. First we found that it was necessary to inject the fish with antibiotics (penicillinstreptomycin) in order to clear tissue of bacterial contamination. Two days later, the spleen was excised and minced with scissors in MEM10. The large number of erythrocytes in the suspension were removed by low centrifugation, then the tissue fragments were incubated on tissue culture flasks at 18°C for 30 days with complete changes of media every other day. After 30 days in culture, primary explants from spleen were composed of three types of cells. The majority were large mononucleate, plecmorphic cells with thinly spread cytoplasm. These cells were trypsinized and subcultured. Another cell types was simple, round cells, somewhat similar to mature lymphocytes, while the third type appeared to be similar to fibroblastic cells. After 9 months with the culture in 17 to 20 passages, the predominate cell type was showing similarities to phagocytic cell. These cells had a marked reticular cytoplasm and grew individually without parallel orientations. By enzyme-specific stains, the cells were observed to have abundant acid phosphatase and β-glucuronidase activities of the cytoplasm. They were negative for peroxidase. The cells were also found to have highly adherent and phagocytic properties when incubated with latex particles. The morphological, enzymatic, and functional findings suggested the possibility that these cells in culture have some properties similar to the cells which are composed of reticulo-endothelial system.