摘要:

Abstract.The life‐cycle ofSaprolegnia parasiticawas considered in relation to the use of protective fungicides against it in salmonid fish hatcheries. Malachite green oxalate was the example fungicide, and all experiments were at 10°C. If the fungicide is to be used as a continuous addition to the water, as a protectant, then target stages of the fungus are identified as zoospores and secondary zoospore cysts: the latter, although physically sedimentary, have a remarkably high degree of buoyancy in the water and hence pose a constant threat to the fish. Continuous addition to the water, to give 0·25 mgl−1malachite green oxalate, would be expected to kill zoospores and zoospore cysts, but 0·05 mgl−1, while allowing zoospore cyst germination, was a strong inhibitor to fungal growth and, aided by natural defences of the fish, might well succeed in disease prevention. If the fungicide is to be used as an intermittent addition to the water (every 24 h), then target stages of the fungus are small mycelia on the fish in addition to zoospores and zoospore cysts in the water. An experimental model was made to consider the vulnerability of these small mycelia, growing on the fish over the preceding 24 h, to malachite green oxalate. If mycelia are of narrow diameter, as expected, then 0·25 mgl−1malachite green oxalate, applied for 15 min, should control their growth and prote

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1992.tb00631.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.Characterization of a red pigmented enterobacterium isolated from natural population of white perch,Morone americanus(Gmelin), during the course of a bacteriological survey in the Back River (Baltimore, Maryland, USA) indicated that the bacterium belonged to the speciesSerratia marcescents.The virulence properties of this isolate (RB 469), studied in comparison with the reference strain ofS. marcescensATCC 1800 andS. plymuthicaK1R, revealed that all the strains were highly pathogenic for fish with LD50s raging from 5 × 103to 1 × 105. Similarly, te extracellular products (ECP) from the three isolates were lethal for fish (LD50ranging from 0·22 to 4·8 μg protein g‐1fish). However, only ECP from strains with strong proteolytic activity (the white perch isolate andS. plymuthica) were cytotoxic for both in fish and homoiothermic cell cultures and both activities were completely destroyed by heating at 100°C for 10min. In contrast, only the twoS. marcescensstrains which possessed phospholipase active were pathogenic for mice and produced enterotoxins. None of theSerratiastrains displayed dermonecrotic factor in rabbits. All these lindings indicate that a direct relationship between eytotoxicity and virulence cannot be esta

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1992.tb00632.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.An antigenic comparison of five rotaviruses isolated from fish in Spain, the USA and Canada was carried out using neutralization, immunodot and ELISA tests. The Spanish isolate (turbot rotavirus) was serologically different from the other four rotaviruses, by neutralization and immunodot. By these two techniques, among the four American strains the two isolates from Canada (smelt rolavirus and Atlantic salmon rotavirus) were closely related antigenically, and the two strains from USA (striped bass rotavirus and the Hetrick&Baya rotavirus, isolated from salmon) seemed to be the same scrotype. These results were supported by those obtained in the comparison of the RNA patterns of the five viruses. However, the antigenie relationships among these rotaviruses were very different when employing the ELISA technique.

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1992.tb00633.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.Ten strains ofVibrio anguillarumproduced three different types of iron‐binding compounds when cultured under different conditions. These were (1) a common phenolate siderophore produced by all strains. (2) a hydroxamate siderophore produced by three strains and (3) a second phenolate siderophore, tentatively identified as anguibactin, produced byV. anguillarumstrain 775 and two other strains, all of which contained a plasmid of 45–50 Md. The relative affinities of these siderophores, determined by competition for55Fe was: anguibactin

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1992.tb00634.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.The Formosa snakehead,Channa maculata(Lacepède), and the largemouth bass,Micropterus salmoides(Lacepède), were given an intraperitoneal (i.p.) and/or intramuscular (i.m.) inoculation ofNocardia asteroidesisolated from cultured Formosa snakehead, Typical granulomatous lesions induced by the experimental fish were similar to the naturally infected cases. The Formosa snakehead showed 100% and 93% mortality at 14 and 35 days after i.m. inoculation with 8 mg and 0·8 mg of bacterial suspension, respectively. The largemouth bass was slightly resistant toN. asteroidesbut still had 95% mortality at 35 days after inoculation (i.m.) with 8 mg bacterial suspension. The bacteria were easily reisolated from spleen and kidney of the experimental fish. Many typical multifocal granulomata were found at the sites of injection and the internal organs such as liver, spleen, kidneys, pancreas, intestine, gills, eyes and brain. The result indicated that theN. asteroidesisolated from the field ease was pathogenic to Formosa snakehead and largemouth ba

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1992.tb00635.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.Supernatants and extracts derived from a commercial heterotrophically grown spray‐dried preparation ofTetraselmis suecicawere observed to inhibitAeromonas hydrophila, A. salmonicida, Lactobacillussp.,Serratia liquefaciens, Staphylococcus epidermidis, Vibrio anguillariim, V. salmonicidaandYersinia ruckeritype I, but notPlanococcussp.,Pseudomonas fluorescens, Streptococcussp.,V. ordaliiorY. ruckeritype II byin vitromethods. When used as a food supplement, the algal cells inhibited laboratory‐induced infections in Atlantic salmon. Moreover, there was a reduction in bacterial numbers in tank water. When used therapcutically, algal cells and their extracts reduced mortalities caused byA, salmonicida, Ser. liquefaciens, V. anguillariim, V. salmonicidaandY. ruckerityp

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1992.tb00636.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.A library of monoclonal antibodies has been developed for use in rapid diagnosis ofVibrioinfecftions. It covers theVibrioSpecies that are regarded as the major fish and shellfish pathogens, many of which are also human pathogens. Blind tests confirm the accurary of the monoclonals as a diagnostic test. Conjugation of enzyme lable onto the monoclonals is providing rapid identification ofVibriospecies by use of direct, rather than indirect, immunological testing.

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1992.tb00637.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.Deformities consisting of an upward curvature of the spine in the caudal region with varying degrees of reduction of the caudal fin were observed in some fry of a laboratory population ofOreochromis niloticus(L.). This spinal deformity was combined with a reduction of the operculum, exposing some gill lamellae. No deformed fry survived for more than 7 days after completion of yolk sac absorption. Breeding tests demonstrate that the mutant phenotype is controlled by a single autosomal recessive gene.

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1992.tb00638.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1992.tb00639.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1992.tb00640.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY