| immunoregulation in fish. i: intramolecular-induced suppression of antibody responses to haptenated protein antigens studied in atlantic salmon (salmo salar l). | we report here evidence for intramolecular-induced suppression of the in vivo antibody response in fish, using a panel of t-dependent hapten-carrier antigens. atlantic salmon were immunized intraperitoneally with protein antigens (limulus polyphemus hemocyanin, chicken gamma globulin, and aeromonas salmonicida a-layer protein) given in their native form or haptenated with either 4-hydroxy-3-iodo-5-nitrophenyl-acetic acid (nip), 2,4,6-trinitrophenyl-acetic acid (tnp), or fluorescein-5-iso-thiocya ... | 1994 | 7521853 |
| role of surface components in serum resistance of virulent aeromonas salmonicida. | the ability of virulent strains of aeromonas salmonicida to resist the bactericidal activity of serum was quantitated. the a. salmonicida strains tested included virulent strains, mutants lacking the major surface a-protein, and mutants lacking a-protein and having a modified lipopolysaccharide structure. the sera evaluated included normal human, rabbit, and trout sera, immune trout serum, and immune rabbit serum containing antibodies to a-protein and lipopolysaccharide. virulent strains of a. s ... | 1982 | 7095843 |
| aeromonas salmonicida resistance to complement-mediated killing. | the resistance of aeromonas salmonicida to complement-mediated killing was investigated by using different strains and their isogenic mutants that had been previously characterized for their surface components. we found that the classical complement pathway is involved in serum killing of susceptible a. salmonicida strains, while the alternative complement pathway seems not to be involved. all of the a. salmonicida strains are able to activate complement, but the smooth strains (with or without ... | 1994 | 7525485 |
| relationships between selected strains of typical and atypical aeromonas salmonicida, aeromonas hydrophila, and haemophilus piscium. | serological analyses of typical and atypical aeromonas salmonicida divided the representative strains into two distinguishable groups based on their antigenic composition. however, the serological groupings do not coincide with divisions constructed on the basis of physiological reactions. all of the a. salmonicida strains and the two a. hydrophila strains examined share at least one antigen and are sensitive to a. salmonicida bacteriophage 40 rr2.8t. these data reinforce the reasons for placing ... | 1980 | 7397604 |
| immunoregulatory activities of eicosanoids in the rainbow trout (oncorhynchus mykiss). | eicosanoids such as prostaglandins (pg), leukotrienes (lt) and lipoxins (lx) have been shown to be potent immunoregulatory molecules in mammals. to determine if they have similar roles in 'lower' animals, rainbow trout (oncorhynchus mykiss) were immunized with either sheep erythrocytes or aeromonas salmonicida in the presence or absence of the stable analogue of pge2, 16,16-dimethyl-pge2, and the number of plaque-forming cells (pfc) or specific antibody levels determined. the higher dose of 16,1 ... | 1995 | 7558126 |
| the interaction of trimethoprim and quinolones against gram-negative fish pathogens. | the effect of combination of trimethoprim with other non-sulphonamide antibacterial agents, in particular oxolinic acid and nalidixic acid, was evaluated against gram-negative fish pathogens. the species included aeromonas salmonicida, yersinia ruckeri, some vibrio spp. and escherichia coli as a reference. the extent of synergy found by other workers with these substances against human gram-negative bacteria was not apparent here. some positive interaction between trimethoprim and oxolinic acid ... | 1995 | 7592108 |
| rapd analysis of aeromonas salmonicida and aeromonas hydrophila. | the randomly amplified polymorphic dna (rapd) technique was used to analyse the genetic differentiation of 13 strains of aeromonas salmonicida subsp. salmonicida, and seven strains of aer. hydrophila. reproducible profiles of genomic dna fingerprints were generated by polymerase chain reaction (pcr) using a single randomly designed primer. the rapd profiles of all the non-motile aeromonads, aer. salmonicida subsp. salmonicida were identical. however, profiles of the motile aeromonads, aer. hydro ... | 1995 | 7592114 |
| assessing glycosidic linkage flexibility: conformational analysis of the repeating trisaccharide unit of aeromonas salmonicida. | a detailed conformational analysis was performed for the synthetic branched trisaccharide beta-d-mannac-(1-->4)-[alpha-d-glc-(1-->3)]-l-rha 1 which represents the repeating unit of the o-antigenic polysaccharide of aeromonas salmonicida. the study was based on 26 experimental noe curves from 1d transient noe experiments, employing gaussian-shaped inversion pulses at 600 mhz. eight of the noe curves were interglycosidic and thus useful for an analysis of glycosidic linkage orientations. metropoli ... | 1994 | 7510557 |
| a conserved aeromonas salmonicida porin provides protective immunity to rainbow trout. | a protein with an apparent m(r) of 28,000 was isolated from outer membrane preparations of aeromonas salmonicida a440. the protein was tested for the ability to form pores, using a planar lipid bilayer model membrane system. the protein appeared to be a monomer with a single-channel conductance in 1.0 m kcl of 1.96 ns and a cation/anion permeability ratio of 2.91 +/- 0.68. these data show that the porin channel is comparable in size to ompc and ompf of escherichia coli and is relatively nonselec ... | 1995 | 7622241 |
| surface phenotypic characteristics and virulence of spanish isolates of aeromonas salmonicida after passage through fish. | eleven strains of aeromonas salmonicida were passaged twice by intraperitoneal injection through rainbow trout and reisolated from the kidney of moribund fish. the surface characteristics and virulence of the strains changed following passage through fish. none of the in vitro tests used could effectively predict the in vivo virulence. | 1995 | 7646039 |
| detection of aeromonas salmonicida, causal agent of furunculosis in salmonid fish, from the tank effluent of hatchery-reared atlantic salmon smolts. | the fish pathogen, aeromonas salmonicida, could be detected only by bacteriological culture from the kidney of dead or moribund fish in one tank in a hatchery rearing atlantic salmon (salmo salar l.) smolts. however, by using a dna probe specific for this species, allied to a pcr assay, the pathogen could be detected in water, feces and effluent samples taken from this fish tank. also, the presence of the pathogen was found in effluent samples from two fish tanks containing apparently healthy fi ... | 1994 | 7527205 |
| phenotypic and molecular characteristics of aeromonas salmonicida subsp. salmonicida isolated in southern and northern finland. | aeromonas salmonicida subsp. salmonicida causes outbreaks of furunculosis in salmonid fish. furunculosis was first detected in finland in 1986 on fish farms located on the finnish coast of the bothnian bay. molecular methods, sds-page, ribotyping, randomly amplified polymorphic dna (rapd) and plasmid profile analysis as well as phenotypic characteristics (biochemical characteristics, maximum growth temperature, pigment and elastase production) were used both for typing the strains and to study t ... | 1995 | 7665387 |
| distribution of surface-exposed and non-accessible amino acid sequences among the two major structural domains of the s-layer protein of aeromonas salmonicida. | the tetragonally arranged crystalline surface protein array (a-layer) of the fish pathogenic bacterium aeromonas salmonicida is a virulence factor. circular dichroism studies in the presence or absence of 0.1% sodium dodecyl sulfate showed that the secondary structure of a-protein, and its 39,439 molecular weight amino-terminal trypsin-resistant peptide, were altered. in both cases alpha-helix was increased significantly at the expense of beta-structure when sds was added. western and dot immuno ... | 1993 | 7692070 |
| identification and characterization of the insertion element is1070 from leuconostoc lactis nz6009. | a novel insertion sequence, designated is1070, was identified on the lactose plasmid of leuconostoc lactis nz6009 by nucleotide sequence analysis. the 1027-bp sequence contains partially matched (24 of 28 bp) inverted repeats and has one long open reading frame. the deduced 305-amino-acid sequence demonstrated homology to transposases of is30 from escherichia coli, is4351 from bacteroides fragilis, is1086 from alcaligenes eutrophus, is1161 from streptococcus salivarius, isas2 from aeromonas salm ... | 1995 | 7698675 |
| ecopathology in aquaculture: risk factors in infectious disease outbreak. | this paper describes a study of the risk factors associated with disease outbreaks in fish species of fish farms and rivers of north-east spain. we focused our work on the isolation of fish pathogens (bacteria, virus), the water quality (physicochemical and microbiological quality) and management characteristics. we have observed 2 important viral diseases, infectious pancreatic necrosis and spring viraemia of carp, and 2 important bacterial ones, furunculosis (aeromonas salmonicida) and bacteri ... | 1995 | 7711777 |
| genetic variation in the humoral immune response against vibrio salmonicida and in antibody titre against vibrio anguillarum and total igm in atlantic salmon (salmo salar). | total igm level and antibody titre to vibrio anguillarum o-antigen after bath-vaccination, and specific antibody response to v. salmonicida o-antigen at three different samplings were analysed in family material of atlantic salmon (salmo salar), consisting of 791 fish belonging to 34 maternal full-sib groups within 12 paternal half-sib groups. the fish were immunized twice, and blood samples collected three times. after the third blood sampling, the fish were challenged with v. anguillarum. medi ... | 1994 | 7725631 |
| vaccination in european salmonid aquaculture: a review of practices and prospects. | disease control by vaccination is widely used in european salmonid aquaculture against vibriosis (vibrio anguillarum), cold-water vibriosis (vibrio salmonicida), yersiniosis or enteric redmouth disease (yersinia ruckeri) and furunculosis (aeromonas salmonicida subsp. salmonicida). the vaccines against the vibrio spp. and y. ruckeri have proven effective especially when administered by injection. furunculosis vaccines have been less successful and have relied on combination with potent adjuvants ... | 1995 | 7735870 |
| the plasmid profiles of fish pathogenic isolates of aeromonas salmonicida, vibrio anguillarum, and vibrio ordalii from the atlantic and pacific coasts of canada. | the plasmid profiles of oxytetracycline- and streptomycin-resistant isolates of aeromonas salmonicida, vibrio anguillarum, and vibrio ordalii were examined by agarose gel electrophoresis. bacterial isolates were from disease outbreaks in fish on the atlantic and pacific coasts. resistant isolates were examined when grown in the presence and absence of antibiotic. alkaline lysis methods were used for plasmid isolation. vibrio spp. were predominantly plasmidless, except for a 47-kilobase (kb) plas ... | 1995 | 7736353 |
| yeast beta-glucan stimulates respiratory burst activity of atlantic salmon (salmo salar l.) macrophages. | previous studies have shown that head kidney macrophages isolated from glucan injected rainbow trout (oncorhychus mykiss) and atlantic salmon (salmo salar l.) have increased ability to kill aeromonas salmonicida. the present work was aimed at investigating the in vitro effects of glucan on the respiratory burst and bactericidal potential of atlantic salmon head kidney macrophages. salmon macrophages were incubated for 1-7 days with various concentrations of yeast beta-glucan (macrogard) and test ... | 1995 | 7615137 |
| physical and functional s-layer reconstitution in aeromonas salmonicida. | the various functions attributed to the s-layer of aeromonas salmonicida have been previously identified by their conspicuous absence in s-layer-defective mutants. as a different approach to establish the multifunctional nature of this s-layer, we established methods for reconstitution of the s-layer of a. salmonicida. then we investigated the functional competence of the reconstituted s-layer. s-layers were reconstituted in different systems: on inert membranes or immobilized lipopolysaccharide ... | 1995 | 7751277 |
| molecular characterization of an aeromonas salmonicida mutant with altered surface morphology and increased systemic virulence. | the asoa gene of aeromonas salmonicida is located approximately 7 kb downstream of the a-layer structural gene, vapa. a 6 kb bamhi fragment containing asoa was cloned and marker-exchange mutagenesis using a kanamycin-resistance cassette was performed to generate an asoa mutation in the low-virulence strain a449l. when analysed by electron microscopy, the mutant a449l-mb exhibited an altered surface morphology. strands and blebs of membranous material were observed protruding from the disorganize ... | 1995 | 7752897 |
| aeromonas spp. can secrete escherichia coli alkaline phosphatase into the culture supernatant, and its release requires a functional general secretion pathway. | aerolysin is a channel-forming protein secreted by aeromonas hydrophila. to determine if regions of aerolysin could direct the secretion of another protein, portions of aera were fused to phoa, the escherichia coli alkaline phosphatase gene and cloned into e. coli, aeromonas salmonicida, and a. hydrophila. we were surprised to find that secretion of the enzyme by both aeromonas spp. was independent of the aerolysin segments fused to it. the smallest fusion product contained only the signal seque ... | 1993 | 7523832 |
| molecular analysis of an a-protein secretion mutant of aeromonas salmonicida reveals a surface layer-specific protein secretion pathway. | the aeromonas salmonicida tn5 mutant, a449-tm1, is unable to secrete the surface layer protein (a-protein) through the outer membrane. immunogold labeling of thin sections of a449-tm1, with polyclonal antisera against the a-protein, showed the accumulation of large quantities of a-protein in an enlarged periplasm. the majority of the labeled a-protein could be seen at the poles of the cells. the ability of a449-tm1 to secrete other extracellular proteins such as hemolysin and protease was not im ... | 1995 | 7739043 |
| fatty acid profiles of "pasteurella" piscicida: comparison with other fish pathogenic gram-negative bacteria. | the fatty acid methyl ester (fame) profiles of "pasteurella" piscicida were determined by gas chromatography and subjected to numerical analysis in comparison with those obtained for vibrio anguillarum, aeromonas salmonicida and pasteurella species of clinical origin. the bacterial species studied shared important characteristics with respect to their fame content: in all of them the saturated and unsaturated fatty acids of 16 carbon atoms were the predominant fatty acids. however, distinguishin ... | 1995 | 7778977 |
| cloning and study of the genetic organization of the exe gene cluster of aeromonas salmonicida. | the aeromonas salmonicida (as) exe gene cluster, an additional member of the pul-related operon family required for general signal-sequence-dependent secretion of proteins from gram- bacteria, was cloned in the broad-host-range cosmid plafr3. twelve genes, exec-n, were identified by partial nucleotide (nt) sequence analyses (exee-n) or determination of the complete sequence (exec and exed). the organisation of the exec-n genes is similar to that of several other operons of this family. these gen ... | 1995 | 7789814 |
| gyra mutations in quinolone-resistant isolates of the fish pathogen aeromonas salmonicida. | gyra mutations in quinolone-resistant isolates of aeromonas salmonicida have been detected by using pcr to amplify the quinolone resistance-determining region of gyra and subsequent cloning and sequencing of pcr products. comparison of nucleotide and derived amino acid sequences of pcr products from quinolone-susceptible and -resistant bacteria revealed a serine 83-to-isoleucine substitution in the gyrase a protein of resistant isolates. one of the resistant isolates differed from the other by a ... | 1994 | 7840589 |
| degradation of propanil by bacterial isolates and mixed populations from a pristine lake. | the microbial transformation rates of propanil, a commonly used herbicide, were investigated using water from a pristine lake in northeast georgia. microbial degradation rates were measured using natural water microflora, the natural water microflora amended with five bacterial species (aerobacter aerogenes, aeromonas hydrophila, acinetobacter calcoaceticus, proteus mirabilis, and aeromonas salmonicida) isolated from the same lake, and the five isolates individually. transformation rate constant ... | 1995 | 7874462 |
| evaluation of the suitability of bis-(1,3-dibutylbarbituric acid) trimethine oxonol, (diba-c4(3)-), for the flow cytometric assessment of bacterial viability. | the usefulness of oxonol (bis-(1,3-dibutylbarbituric acid)trimethine oxonol) as a generally applicable indicator of bacterial viability was investigated using untreated and killed cultures of a variety of bacterial genera. killing methods involved either heat or bactericidal antibiotics. for all strains tested, the fluorescent dye showed significantly more intense staining of killed than untreated cells. the sensitivity of aeromonas salmonicida to gentamicin was assessed using oxonol. although t ... | 1995 | 7649437 |
| three beta-lactamases isolated from aeromonas salmonicida, including a carbapenemase not detectable by conventional methods. | the beta-lactamases of seven strains of aeromonas salmonicida subsp. achromogenes resistant to amoxicillin (mic > 1024 mg/l) and responsible for furunculosis in farmed atlantic salmon in scotland were examined to establish the mechanisms of beta-lactam resistance. separation of a cell-free extract on an isoelectric focusing gel stained with the chromogenic cephalosporin nitrocefin showed the presence of two beta-lactamases, one with a pi of 7.9 and the other with a pi of 6.0. hydrolysis assays o ... | 1994 | 7889949 |
| relationship between resistance of salmonids to furunculosis and recovery of aeromonas salmonicida from external mucus. | fish were sampled at the ed weed state fish hatchery (south hero, vermont, usa) in september 1992. aeromonas salmonicida was common, with concentrations as high as 10(5) to 10(7) colony-forming units per gram of mucus, and readily recovered from most mucus samples obtained from furunculosis-sensitive populations of brook trout (salvelinus fontinalis), lake trout (salvelinus namaycush), and atlantic salmon (salmo salar). the pathogen was the predominant microorganism and accounted for greater tha ... | 1994 | 7760494 |
| characterization of aeromonas salmonicida subsp. salmonicida: a comparative study of strains of different geographic origin. | a total of 130 strains of the fish pathogen aeromonas salmonicida isolated in denmark, norway, scotland, canada and the usa were examined. the strains originated from farmed salmonid fish. the biochemical, physiological and serological characteristics, antibiotic resistance patterns and cell surface-related properties were compared. aeromonas salmonicida was found to be remarkably consistent in general cultural and biochemical characteristics. it is noteworthy that the strains were positive in t ... | 1994 | 7928780 |
| isolation of aeromonas salmonicida from paddlefish, polyodon spathula. | aeromonas salmonicida was isolated from paddlefish (polyodon spathula) mortalities collected during an epizootic of furunculosis at the spring river state hatchery, arkansas (usa), in 1992. isolates of the bacterium were obtained from culture of gill and kidney tissue. this is the first epizootic of bacterial etiology to be reported in paddlefish. | 1994 | 7933294 |
| genetic variation in the humoral immune response in atlantic salmon (salmo salar) against aeromonas salmonicida a-layer. | antibody responses to aeromonas salmonicida a-layer were analysed in family material of atlantic salmon (salmo salar), consisting of 791 fish belonging to 34 full-sib groups within 12 paternal half-sib groups. the fish were immunized twice and blood samples were collected three times. significant increase in antibody titre from first to second, and from second to third sampling, was observed. genetic variation in antibody titres was observed at the three samplings with estimated heritabilities r ... | 1994 | 7941312 |
| modulation of the bacterial clearance activity of haemocytes from the freshwater mollusc, lymnaea stagnalis, by the avian schistosome, trichobilharzia ocellata. | the ability of haemocytes, from the haemolymph of the gastropod mollusc lymnaea stagnalis, to recognize and eliminate the bacterium aeromonas salmonicida was shown using an in vitro bacterial clearance assay. the assay employs a dye which is reduced by a. salmonicida in direct proportion to the number of viable bacteria resulting in a colour change which can be determined spectrophotometrically. addition of cytochalasin b resulted in a marked decrease in bacterial clearance, implicating both int ... | 1994 | 7970887 |
| antigen-induced release of macrophage activating factor from rainbow trout oncorhynchus mykiss leucocytes. | the production of macrophage-activating factor (maf) by rainbow trout, oncorhynchus mykiss, head kidney leucocytes at varying times post-immunisation, with the fish bacterial pathogen, aeromonas salmonicida, was investigated and correlated with head kidney lymphocyte proliferation and serum antibody production. maf production was preceded by lymphocyte proliferation and both responses were highest using whole bacterial cells as the in vitro stimulant. maf production and antibody production incre ... | 1994 | 7975191 |
| atypical aeromonas salmonicida isolated from ulcerated chub leuciscus cephalis. | | 1994 | 7992477 |
| characteristics of 'atypical', cytochrome oxidase-negative aeromonas salmonicida isolated from ulcerated flounders (platichthys flesus (l.)). | 'atypical', cytochrome oxidase-negative variants of the fish pathogen aeromonas salmonicida, isolated from ulcerated flounder (platichthys flesus), were studied using different methods. two of the strains possessed a protein that corresponded to the a-layer protein of aer. salmonicida. the strains reacted with antibodies against the a-layer and monoclonal antibodies against the o-antigen of typical aer. salmonicida. these tests confirm that the isolates from flounder should be classified as aer. ... | 1994 | 8005836 |
| dietary intake of immunostimulants by rainbow trout affects non-specific immunity and protection against furunculosis. | immunostimulant preparations macrogard, candida utilis, saccharomyces cerevisiae, evetsel, chitosan, or finnstim were mixed into semipurified diets and fed to groups of rainbow trout for 1 week. fish were bled by non-lethal caudal puncture and blood samples assayed for changes in non-specific cellular immunity and humoral protein levels. in the immunostimulated fish, hematocrit levels and lymphocyte counts remained relatively stable; however, elevations were observed in oxidative radical release ... | 1994 | 8066989 |
| [the comparative characteristics of the antibiotic sensitivity of psychrophilic and mesophilic aeromonads]. | the general regularities of the antibiotic susceptibility of psychrophilic and mesophilic aeromonads were determined. the antibioticograms were in general similar. still, there was observed a higher susceptibility of aeromonas salmonicida to tetracycline, chloramphenicol and rifampicin, as well as a larger number of strains susceptible to semisynthetic broad spectrum penicillins (ampicillin and carbenicillin) and cephazoline. the susceptibility to aminoglycosides was lower. | 1993 | 8085887 |
| endogenous mutagenesis by an insertion sequence element identifies aeromonas salmonicida abca as an atp-binding cassette transport protein required for biogenesis of smooth lipopolysaccharide. | analysis of an aeromonas salmonicida a layer-deficient/o polysaccharide-deficient mutant carrying a tn5 insertion in the structural gene for a protein (vapa) showed that the abca gene immediately downstream of vapa had been interrupted by the endogenous insertion sequence element isas1. immunoelectron microscopy showed that o polysaccharides did not accumulate at the inner membrane-cytoplasm interface of this mutant. abca encodes an unusual protein; it carries both an amino-terminal atp-binding ... | 1995 | 7777581 |
| amoxicillin concentrations in the serum of atlantic salmon (salmo salar l) during furunculosis therapy. | the effectiveness of the delivery of amoxicillin to atlantic salmon, undergoing chemotherapy in natural outbreaks of furunculosis in sea-cages, was investigated by measuring the concentration of the drug in serum samples. five groups of 50 sera from three outbreaks were collected two hours after oral treatment with doses of 80 or 120 mg/kg bodyweight. amoxicillin was detected in 82, 82, 92, 100 and 90 per cent of the sera in the five groups (limit of detection 0.16 microgram/ml). many sera conta ... | 1993 | 8128552 |
| antigenicity of the aeromonas salmonicida maltose-inducible outer membrane porin (maltoporin) and a hybrid protein derived from it. | | 1993 | 8131922 |
| mutagenesis of the paracrystalline surface protein array of aeromonas salmonicida by endogenous insertion elements. | the tetragonal paracrystalline surface protein array (a-layer) of the fish pathogenic bacterium aeromonas salmonicida is a virulence factor and bacteria which are unable to produce a-layer are attenuated in their ability to kill fish. ten independent mutants of aeromonas salmonicida which were unable to produce a-layer were isolated by growth at 30 degrees c. these mutants displayed either reduced synthesis of the a-layer subunit, synthesis of a truncated subunit, or complete loss of the ability ... | 1994 | 8151705 |
| biological markers of macrophage activation: applications for fish phagocytes. | the immune defence mechanisms of fish seem to be related and similarly competent to those of mammals. because of this, there is an increased interest in the immune responses of fish as models for higher vertebrates in immunological/immunotoxicological studies. macrophages (m phi), phagocytic cells of the mammalian and teleost immune system which reside in tissues, represent a quiescent population of cells. however, upon stimulation, alterations in the physiology of these resident m phi occur whi ... | 1993 | 8244466 |
| fate of the fish pathogen aeromonas salmonicida in the peritoneal cavity of rainbow trout. | a model was developed to study the fate of the fish pathogen aeromonas salmonicida in vivo, inside a specialized intraperitoneal chamber implanted in rainbow trout, oncorhynchus mykiss. although normally recalcitrant to lytic agents in vitro, owing to the presence of its regular surface array (s layer), a. salmonicida was rapidly killed in the peritoneal cavity by a host-derived, soluble lytic activity present in peritoneal fluid. peritoneal fluid was also found to kill other bacteria and lyse v ... | 1993 | 8306206 |
| cloning and characterization of three hemolysin genes from aeromonas salmonicida. | two hemolysin genes (ash3 and ash4) of aeromonas salmonicida strain 17-2 and one (ash1) of a. salmonicida atcc14174 were cloned into the cosmid vector charomid 9-36 in escherichia coli dh1. the overall amino acid sequence of the ash3 was similar to that of the aerolysins of aeromonas hydrophila and aeromonas sobria, and hemolysins ahh3, ahh4, and ahh5 of a. hydrophila, and hemolysin asa1 of a. sobria. the sequence of ash4 was similar to that of the ahh1 hemolysin of a. hydrophila. the ash4 hemol ... | 1993 | 8309354 |
| assessment of the antimicrobial sensitivity of aeromonas salmonicida isolates from farmed atlantic salmon in scotland. | sixty-five isolates of aeromonas salmonicida were assessed for antimicrobial sensitivity by disc diffusion tests and the results compared with the minimum inhibitory concentration for each isolate. the results demonstrated that disc diffusion, using a standard technique, may be used to categorize isolates as sensitive or resistant provided that the corresponding minimum inhibitory concentrations are known. | 1993 | 8310605 |
| the effect of iron limitation on the growth of aeromonas salmonicida. | the effects of the iron-chelating agents ethylenediamine dihydroxyphenylacetic acid (edda), 2,2'-dipyridyl (dipy) and 8-hydroxyquinoline (8hq) on the growth of aeromonas salmonicida were examined. in these studies, edda caused a small decrease in growth, whereas dipy and 8hq reduced cell growth by 50 and 90%, respectively. the extracellular products contained a greater proportion of the major protease (70 kd) when cells were grown in the presence of the chelating agents. analysis of the outer me ... | 1993 | 8336555 |
| phagocytic defence mechanism in sea bass (dicentrarchus labrax l.): an ultrastructural study. | the ultrastructure of the phagocytic process in fish has not been established in spite of the significant morphofunctional differences detected in the fish immune system with respect to the basic immunological pattern in vertebrates. we report the ultrastructure of the bacterial phagocytic defence mechanism in sea bass (dicentrarchus labrax l.). | 1994 | 7879910 |
| aeromonas salmonicida grown in vivo. | the virulent fish pathogen aeromonas salmonicida was rapidly killed in vivo when restricted inside a diffusion chamber implanted intraperitoneally in rainbow trout. after a period of regrowth, the survivors had acquired resistance to host-mediated bacteriolysis, phagocytosis, and oxidative killing, properties which were subsequently lost by growth in vitro. resistance to bacteriolysis and phagocytosis was associated with a newly acquired capsular layer revealed by acidic polysaccharide staining ... | 1993 | 8359906 |
| spread of the bacterial fish pathogen aeromonas salmonicida after importation of infected goldfish, carassius auratus, into australia. | | 1993 | 8117214 |
| activation of rainbow trout (oncorhynchus mykiss) phagocytes by muramyl dipeptide. | immunoenhancing activity of synthetic muramyl dipeptide (mdp) was investigated in relation to the activation of rainbow trout (oncorhynchus mykiss) phagocytes and to nonspecific protection against challenge with the fish pathogen aeromonas salmonicida. head kidney phagocytes collected from mdp-injected fish showed significant chemotactic activity against zymosan-activated normal rainbow trout serum, and phagocytic activities against both a. salmonicida and plastic beads. the mdp-activated phagoc ... | 1993 | 8388812 |
| molecular cloning and nucleotide sequence analysis of the maltose-inducible porin gene of aeromonas salmonicida. | the gene for the aeromonas salmonicida maltose-inducible porin (maltoporin) was cloned into phagemid ptz18r in two restriction fragments, 0.6-kb psti/kpni and 1.7-kb sphi, of genomic dna and their nucleotide sequences were determined. open reading frames of 1329 and 1335 bp translated into sequences of 443 and 445 amino acids, with a 23 or 25 amino acid signal sequence and a 420 amino acid mature protein of molecular mass 46424 da. putative ribosome binding sites, agga and gggaa, occurred 9 bp u ... | 1993 | 8405961 |
| novel antigens expressed by aeromonas salmonicida grown in vivo. | virulent and avirulent aeromonas salmonicida strains grown inside intraperitoneal implants in rainbow trout (oncorhynchus mykiss) were examined for unique antigen expression. western blots (immunoblots), performed with immune rabbit serum raised against in vivo-grown cells, revealed several unique antigens. with the exception of lipopolysaccharide (lps), these novel antigens were destroyed after proteinase k treatment. the majority of these antigens were not induced in vitro in response to eithe ... | 1993 | 8406855 |
| physiological consequences of the s-layer of aeromonas salmonicida in relation to growth, temperature, and outer membrane permeation. | s-layers are paracrystalline protein multimers that cover the entire cell surface of many bacterial species. the presence of an s-layer in aeromonas salmonicida (also known as a-layer) predisposed this bacterium to apparently unrelated physiological consequences: inhibition of growth at 30 degrees c, enhanced cell filamentation at 37 degrees c, and enhanced uptake of the hydrophobic antibiotics streptonigrin and chloramphenicol. growth inhibition or enhanced filamentation was not observed when t ... | 1994 | 7922885 |
| effects of nutrients on exopolysaccharide production and surface properties of aeromonas salmonicida. | extracellular polysaccharide (eps) and capsular polysaccharide (cps) production by aeromonas salmonicida a450 and the influence of the capsule on cell surface properties were studied. a. salmonicida did not produce cps or eps when glucose, phosphate, magnesium chloride, or trace mineral components were absent from the medium. the addition of yeast extract improved capsule production. neither eps nor cps formation depended on the c/n ratio, although it appeared to be influenced by the level of ca ... | 1993 | 8368833 |
| high-affinity binding of the basement membrane protein collagen type iv to the crystalline virulence surface protein array of aeromonas salmonicida. | the surface of the fish pathogen aeromonas salmonicida is covered by a paracrystalline array (the a-layer) which is a virulence factor for the organism. quantification of the ability of a. salmonicida cells to bind collagen types i and iv in a 125i-radiolabelled liquid-phase assay showed that a-layer-positive cells bound high levels of collagen type iv, but significantly lower levels of collagen type i. collagen type iv binding was confirmed using non-radiolabelled enzyme-linked immunosorbent as ... | 1993 | 8459775 |
| an aromatic-dependent mutant of the fish pathogen aeromonas salmonicida is attenuated in fish and is effective as a live vaccine against the salmonid disease furunculosis. | aeromonas salmonicida is the etiological agent of furunculosis in salmonid fish. the disease is responsible for severe economic losses in intensively cultured salmon and trout. bacterin vaccines provide inadequate protection against infection. we have constructed an aromatic-dependent mutant of a. salmonicida in order to investigate the possibility of an effective live-attenuated vaccine. the aroa gene of a. salmonicida was cloned in escherichia coli, and the nucleotide sequence was determined. ... | 1993 | 8478107 |
| host range and transfer efficiency of incompatibility group hi plasmids. | hi plasmids are distinguished by their thermosensitive mode of conjugation (transfer efficiency is optimal at 22-30 degrees c) and their capacity to encode multiple antibiotic resistance. these traits have implicated hi plasmids as potential vectors in the dissemination of antibiotic resistance among pathogenic and indigenous bacterial species in water and soil environments. we compared the transfer efficiency of hi plasmids with that of plasmids from 13 other incompatibility groups at 37, 24, a ... | 1993 | 8358670 |
| an aeromonas salmonicida gene which influences a-protein expression in escherichia coli encodes a protein containing an atp-binding cassette and maps beside the surface array protein gene. | a conserved aeromonas salmonicida gene (abca) affecting expression of the surface array protein gene (vapa) in escherichia coli was identified. the 924-bp gene starts 205 bp after vapa and codes for a protein with a deduced molecular weight (m(r)) of 34,015 containing an n-terminal p-loop and significant homology to the atp-binding cassette transport protein superfamily. abca was identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (sds-page) by using t7 polymerase expression ... | 1993 | 8491726 |
| development of a specific biotinylated dna probe for the detection of renibacterium salmoninarum. | a specific dna probe for the identification of renibacterium salmoninarum, the causative agent of bacterial kidney disease (bkd), was developed from one of 3 clones prs47, prs49, and prs26 of 5.1 kb, 5.3 kb, and 11.3 kb, respectively. the biotinylated prs47/bamhi insert probe was tested on 3 dilutions of dna extracted from 3 strains of r. salmoninarum and from 1 strain each of arthrobacter protophormiae, aeromonas salmonicida, corynebacterium aquaticum, carnobacterium piscicola, listonella angui ... | 1995 | 8548693 |
| study of the humoral response of atlantic salmon (salmo salar l.), naturally infected with aeromonas salmonicida ssp. achromogenes. | the humoral antibody response of healthy atlantic salmon and of two groups of salmon, naturally infected with aeromonas salmonicida ssp. achromogenes, was examined in some detail. one diseased group was chronically infected and the other recently infected. it was found that the humoral response of these two infected groups was quite different. the chronically infected fish showed poor specific response to the causative agent whereas the recently infected salmon produced strong specific antibody ... | 1995 | 8588335 |
| capsulated cells of aeromonas salmonicida grown in vitro have different functional properties than capsulated cells grown in vivo. | when grown in vivo in the peritoneal cavity of rainbow trout, aeromonas salmonicida produces a clearly defined capsule with virulence-related functions. aeromonas salmonicida grown in vitro in a glucose-rich medium (grm) has also been reported to reproduce capsular material. because in vitro mimicry of in vivo induced traits is highly desirable in vaccine design, the extent to which growth in grm mimicked in vivo growth was examined. antibodies specific to in vivo grown cells partially labeled t ... | 1995 | 8590408 |
| vibrio spp. secrete proaerolysin as a folded dimer without the need for disulphide bond formation. | proaerolysin is an extracellular dimeric protein that is secreted across the inner and outer membranes of aeromonas spp. in separate steps. to investigate the role of protein folding in the second step, one or more cysteine residues were introduced and the mutant proaerolysins were expressed in aeromonas hydrophila and aeromonas salmonicida, as well as vibrio cholerae. replacing met-41 with cys resulted in expression of a protein that could form a dimer in which the monomers were linked together ... | 1995 | 8594324 |
| aeromonas salmonicida possesses two genes encoding homologs of the major outer membrane protein, ompa. | two homologs of the outer membrane protein ompa were identified in aeromonas salmonicida by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immunoblotting, and amino-terminal sequence analyses. an a. salmonicida genomic dna library was constructed by using lambda gem-11 and recombinant phage carrying both genes ompai and ompaii) selected by immunoscreening. a 5.0-kb bamhi fragment containing the two genes in tandem was subcloned in pbluescript and used for further subcloning and seque ... | 1996 | 8626290 |
| immunotoxic effects of copper and cadmium in the sea bass dicentrarchus labrax. | two phagocytes-mediated activities of the sea bass dicentrarchus labrax were examined after exposure to sublethal concentrations of copper and cadmium: (a) phagocytosis (measured by phagocytotic index), and (b) the production of reactive oxygen intermediates (luminol-dependent chemiluminescence) in response to bacteria aeromonas salmonicida. in vivo exposure for 48 h to each metal separately by intraperitoneal injection did not affect the quantity of phagocytes of pronephros and their viability ... | 1996 | 8683034 |
| characterization of atypical aeromonas salmonicida isolates by ribotyping and plasmid profiling. | a total of 38 strains of atypical aeromonas salmonicida, three oxidase-negative but otherwise typical aer. salmonicida, three typical aer. salmonicida, and two reference strains, isolated from several countries and fish species were examined with respect to rrna gene restriction patterns (ribotypes) and plasmid profiles. most epidemiologically unrelated strains had different ribotypes, whereas isolates from the same outbreak were identical. all strains, except one, carried one or more large plas ... | 1996 | 8698652 |
| utilization of transferrin and salmon serum as sources of iron by typical and atypical strains of aeromonas salmonicida. | the ability of typical and atypical strains of aeromonas salmonicida to utilize non-haem sources of protein-bound iron was evaluated. (i) in a plate bioassay, the suppression of growth imposed on typical and atypical a. salmonicida by addition of the high-affinity iron chelator ethylenediamine-di(o- hydroxyphenylacetic acid) (edda) to the growth medium was reversed by the addition of 30% or 90% iron-saturated bovine or human transferrin (tf) or lactoferrin (lf) to the growth medium. (ii) the mec ... | 1996 | 8704995 |
| survival of nonculturable aeromonas salmonicida in lake water. | the survival of aeromonas salmonicida subsp. salmonicida was investigated in sterile and untreated lake water. in sterile lake water (filtered and autoclaved), it was found that cells of a. salmonicida entered a nonculturable but viable condition. viability was determined by flow cytometry with the dye rhodamine 123, which is taken up and maintained within cells with a membrane potential. for survival studies in untreated lake water, a. salmonicida was marked with the xyle gene by using the plas ... | 1993 | 8481011 |
| a live (delta aroa) aeromonas salmonicida vaccine for furunculosis preferentially stimulates t-cell responses relative to b-cell responses in rainbow trout (oncorhynchus mykiss). | we have previously described (l. m. vaughan, p. r. smith, and t. j. foster, infect. immun. 61:2172-2181, 1993) the construction of a kanamycin-resistant aromatic-dependent mutant of aeromonas salmonicida, the causative agent of furunculosis, and its use as a live vaccine. here we describe the construction of an unmarked aroa deletion mutant and examine the nature and magnitude of immune responses in rainbow trout (oncorhynchus mykiss) to this vaccine strain. good proliferative and antibody respo ... | 1996 | 8751940 |
| atypical aeromonas salmonicida isolated from diseased turbot (scophtalmus maximus l.). | atypical aeromonas salmonicida were isolated from 3 outbreaks of disease among farmed turbot (scophthalmus maximus l.) in 3 different farms, 1 from norway (n1) and 2 from denmark (dk1 and dk2). in all 3 cases, the incidence of disease and mortality was high and the main characteristic pathological finding was skin ulcers and septicaemia. the isolated bacteria were subjected to a thorough phenotypic and genotypic examination and comparison in the laboratory. all 3 isolates belonged to a. salmonic ... | 1996 | 8767692 |
| multiple regulation of carp (cyprinus carpio l.) macrophages and neutrophilic granulocytes by serum factors: influence of infection with atypical aeromonas salmonicida. | normal carp serum contains inhibitory and stimulatory factors for macrophage and neutrophilic granulocyte respiratory burst activity. as stimulatory factors were only effective in combination with phorbol myristate actetate (pma) activation, it is concluded that they are probably linked to protein kinase c activation. both the stimulatory and inhibitory factors are heat stable. macrophage- and neutrophilic granulocyte-enriched cell fractions from the pronephros of carp had high respiratory burst ... | 1996 | 8797288 |
| survival of cells and dna of aeromonas salmonicida released into aquatic microcosms. | the survival of the bacterial fish pathogen aeromonas salmonicida, and persistence of its dna, were monitored in aquatic microcosms using selective culture and most probable number pcr. bacterial cells and naked dna were released into natural non-sterile microcosms consisting of lake sediment overlayered with lake water. two different types of surface sediment were used. one was sandy in character, taken from the shoreline whilst the other was a littoral loamy surface mud. inoculated cells and n ... | 1996 | 8810058 |
| the role of the capsular polysaccharide of aeromonas salmonicida in the adherence and invasion of fish cell lines. | the ability of several aeromonas salmonicida strains grown under different conditions (capsulated and non-capsulated) to adhere to and invade two fish cell lines was compared. the level of adherence was slightly higher when the strains were grown under conditions promoting capsule formation than when the same strains were grown under conditions which did not promote capsule formation. however, the most significant difference among the wild-type strains grown under conditions promoting capsule fo ... | 1996 | 8810501 |
| a comparison of the amino acid sequence of the serine protease of the fish pathogen aeromonas salmonicida subsp. salmonicida with those of other subtilisin-type enzymes relative to their substrate-binding sites. | the amino acid sequence of the so-called 70 kda (actually 64 kda) serine protease secreted by the gram-negative fish pathogen aeromonas salmonicida has been determined. it shows a high degree of homology with the complete sequence of other bacterial serine proteases which, with molecular masses of approximately 30 kda, are less than half its size. this homology is particularly marked in regions adjacent to the catalytic triad asp32, his64 and ser221 of subtilisin bpn'. significant features of th ... | 1993 | 8436946 |
| an aeromonas salmonicida gene required for the establishment of infection in rainbow trout (oncorhynchus mykiss). | the asob gene of aeromonas salmonicida is located approximately 9 kb downstream of the structural gene (vapa) for the surface layer (a-layer). the nucleotide sequence of asob was determined and found to encode a putative polytopic cytoplasmic membrane protein which exhibited homology to a number of bacterial transport proteins. allele exchange mutagenesis of asob resulted in a mutant (a449-d) which was avirulent when administered by bath immersion. however, when administered by intraperitoneal i ... | 1996 | 8917088 |
| cloning, characterization and expression of the reca gene of aeromonas salmonicida. | the aeromonas salmonicida a449 reca gene has been cloned, sequenced and expressed in vitro. the predicted amino acid sequence of a. salmonicida reca was determined and, when compared to other reca, was found to possess a number of domains identical to those characterized in escherichia coli reca. the a. salmonicida reca was mobilized into an e. coli reca mutant strain and was shown to allow increased survival in the presence of the chemical mutagen mms and after ultraviolet (uv) irradiation. the ... | 1996 | 8917089 |
| the cell surface of aeromonas salmonicida determines in vitro survival in cultured brook trout (salvelinus fontinalis) peritoneal macrophages. | aeromonas salmonicida strains phenotypically differing in their a-layer, lipopolysaccharide, and macrophage cytotoxicity were tested in vitro for survivability in brook trout (salvelinus fontinalis) serum with or without antibodies, and in vivo following intraperitoneal injection. the ability of brook trout peritoneal macrophages to phagocytize and kill the different phenotypes was investigated in an in vitro assay. the virulent strain, a. salmonicida 80204, which has the full complement of know ... | 1996 | 8971685 |
| a 70 kda aeromonas salmonicida serine protease - beta-galactosidase hybrid protein as an antigen and its protective effect on atlantic salmon (salmo salar l.) against a virulent a. salmonicida challenge. | | 1993 | 8449332 |
| characterization of a stable l-form of the fish pathogen aeromonas salmonicida. | a stable l-form of aeromonas salmonicida, which resulted from induction with benzylpenicillin, contained more of an outer membrane protein, with an estimated molecular weight of 40 kda but less of 47.9 and 38 kda proteins, than did parental walled cells. in addition, from western blots, two protein bands reacted strongly with a polyclonal antiserum. the antiserum did not react demonstrably with the band detected in the l-forms on the gels. | 1996 | 8987904 |
| in vivo production of a-protein, lipopolysaccharide, iron-regulated outer membrane proteins and 70-kda serine protease by aeromonas salmonicida subsp. salmonicida. | using specific immunostaining of western blots, the in vivo expression of several putative virulence factors of aeromonas salmonicida subsp. salmonicida was demonstrated in infected muscle tissue of atlantic salmon and rainbow trout. three virulent isolates of a. salmonicida were used. one isolate was chosen because in vitro it was apparently a non-producer of the 70-kda serine protease. infected furuncle tissue was centrifuged and samples of the pellet and supernatant probed for evidence that t ... | 1997 | 9141656 |
| application of a modified disc diffusion technique to antimicrobial susceptibility testing of vibrio anguillarum and aeromonas salmonicida clinical isolates. | two techniques for antimicrobial susceptibility testing of vibrio anguillarum and aeromonas salmonicida strains were compared. the first method was the reference test that determines minimal inhibitory concentrations (mic); the second was a modified diffusion test that measures the inhibitory concentrations in diffusion (icd) by carrying out the diffusion test with five discs of differing contents. icd measurement was not applicable for the susceptibility testing of oxytetracycline and sulfadime ... | 1996 | 8828130 |
| acute phase proteins in salmonids: evolutionary analyses and acute phase response. | inflammation induces dramatic changes in the biosynthetic profile of the liver, leading to increased serum concentrations of positive acute phase (ap) proteins and decreased concentrations of negative ap proteins. serum amyloid a (saa) and the pentraxins c-reactive protein (crp) and serum amyloid p component (sap) are major ap proteins: their serum levels can rise by 1000-fold, indicating that they play a critical role in defense and/or the restoration of homeostasis. we have cloned saa and a sa ... | 1997 | 8977214 |
| the effect of temperature and water quality on antibody response to aeromonas salmonicida in sunshine bass (morone chrysops x morone saxatilis). | the kinetics of the antibody response to aeromonas salmonicida were determined in sunshine bass (hybrid striped bass: female morone chrysops x male morone saxatilis) acclimated to 10, 18, 24, 29 degrees c, and to 0.15 mg 1(-1) un-ionized ammonia and 200 mg 1(-1) nitrate levels. temperature and water quality factors affected the immune response of sunshine bass. temperatures of 10 degrees c and 18 degrees c decreased the magnitude and delayed the time of the antibody response to a. salmonicida. t ... | 1996 | 9157680 |
| complement resistance of capsulated strains of aeromonas salmonicida. | the complement resistance of aeromonas salmonicida strains grown under conditions promoting capsule formation was investigated using well characterized strains and their isogenic mutants. complement resistance was previously studied using the same strains growing under non-capsulating conditions. the serum resistant strains were found to activate complement, but rapidly degrade c3b preventing productive formation of the lytic complex c5b-9. isogenic lipopolysaccharide rough mutants grown under n ... | 1997 | 9160301 |
| identification of a second endogenous porphyromonas gingivalis insertion element. | in this study a second endogenous porphyromonas gingivalis insertion element (is element) that is capable of transposition within p. gingivalis was identified. nucleotide sequence analysis of the tn4351 insertion site in a p. gingivalis tn4351-generated transconjugant showed that a complete copy of the previously unidentified is element, designated pgis2, had inserted into is4351r in tn4351. pgis2 is 1,207 bp in length with 19-bp imperfect terminal inverted repeats, and insertion resulted in a d ... | 1997 | 9171437 |
| cloning and nucleotide sequence of the dna gyrase gyra gene from the fish pathogen aeromonas salmonicida. | the dna gyrase gyra gene from the fish pathogen aeromonas salmonicida 2148/89 was cloned, and the nucleotide sequence was determined. an open reading frame of 2,766 nucleotides was identified and was found to encode a protein of 922 amino acids with a calculated molecular mass of 101.1 kda. the derived amino acid sequence shared a high degree of identity with other dna gyrase a proteins, in particular, with other gram-negative gyra sequences. when the amino acid sequence of a. salmonicida gyra w ... | 1996 | 8723452 |
| purification and properties of an aminopeptidase from a protamine-degrading marine bacterium. | a protamine-degrading marine bacterium was isolated from marine soil and identified as aeromonas salmonicida subsp. based on its taxonomical characteristics. an alanine-specific aminopeptidase, called aminopeptidase k, from an extract of the strain was purified and characterized. the aminopeptidase k was purified about 80-fold by fractionation with ammonium sulfate and column chromatography on qa-52 cellulose, phenyl superose and superose 12. the purified enzyme is composed of 6 subunits of 86 k ... | 1997 | 9255972 |
| adjuvants and immunostimulants for enhancing vaccine potency in fish. | adjuvants combined with immunogens are effective enhancers of the immune response in fish. as in other animals, substances such as freund's complete and incomplete adjuvants, light oils and bacterial lipopolysaccharides have been shown to induce elevated antibody production when added to bacterins and administered to fish. light oil adjuvants are now used successfully with injectable bacterins of aeromonas salmonicida, and in multivalent fish vaccines where a. salmonicida is combined with yersin ... | 1997 | 9270854 |
| vaccinated fish welfare: protection versus side-effects. | active immunisation of fish involves a number of potentially harmful procedures like handling, anaesthesia or injection of more or less toxic substances. adjuvanted vaccines may cause inflammation, granuloma and pigmentation at the site of injection. intraperitoneal administration of oil-adjuvanted vaccines to atlantic salmon pre-smolts has occasionally resulted in impaired growth and reduced carcass quality. the consequences of such vaccination for fish welfare may therefore be questioned. with ... | 1997 | 9270866 |
| vaccination strategies in freshwater salmonid aquaculture. | the focus of this chapter is antibacterial vaccines. the main salmonid species in freshwater aquaculture is the rainbow trout. other salmonid species are produced on a limited scale. the most important bacterial fish diseases in european freshwater aquaculture are the rainbow trout fry syndrome-rtfs-(flavobacterium psychrophilum) and enteric redmouth disease-erm-(yersinia ruckeri) which are widespread and cause serious epizootics, while furunculosis (aeromonas salmonicida) is endemic, only givin ... | 1997 | 9270868 |
| [recent knowledge on fish pathogenic bacteria aeromonas salmonicida, listonella anguillara and cytophaga columnaris, and their virulence factors]. | | 1997 | 9155200 |
| molecular and phenotypic methods for the characterization of atypical aeromonas salmonicida. | atypical aeromonas salmonicida form a taxonomically diverse group among the psychrophilic a. salmonicida. characteristics of 53 atypical a. salmonicida strains originating from finland, denmark, norway and sweden were studied using 60 phenotypic tests. ribopattern analysis and plasmid profiles were used as genetic methods. the production of brown pigment on the furunculosis agar containing l-tyrosine divided the atypical oxidase-positive strains into two groups: pigment-producing (n = 35) and ac ... | 1997 | 9228690 |
| the disulfide bond in the aeromonas hydrophila lipase/acyltransferase stabilizes the structure but is not required for secretion or activity. | vibrio and aeromonas spp. secrete an unusual 35-kda lipase that shares several properties with mammalian lecithin-cholesterol acyltransferase. the aeromonas hydrophila lipase contains two cysteine residues that form an intramolecular disulfide bridge. here we show that changing either of the cysteines to serine does not reduce enzymatic activity, indicating that the disulfide bond is not required for correct folding. however, when either of the cysteines is replaced, the enzyme is more readily d ... | 1997 | 9150203 |
| the synthesis, secretion and role in virulence of the paracrystalline surface protein layers of aeromonas salmonicida and a. hydrophila. | the s-layers of the aeromonas spp. studied to date are composed of identical protein subunits which are translocated across the cytoplasmic membrane, periplasm and outer membrane to the cell surface, where they are assembled and tethered to the cell via an interaction with the o-polysaccharide side chains of the lipopolysaccharide. aeromonas s-layers have the ability to bind a number of host factors such as fibronectin, laminin and vitronectin as well as providing resistance to serum killing and ... | 1997 | 9297815 |
| quorum sensing in aeromonas hydrophila and aeromonas salmonicida: identification of the luxri homologs ahyri and asari and their cognate n-acylhomoserine lactone signal molecules. | spent culture supernatants from both aeromonas hydrophila and aeromonas salmonicida activate a range of biosensors responsive to n-acylhomoserine lactones (ahls). the genes for a quorum sensing signal generator and a response regulator were cloned from each aeromonas species and termed ahyri and asari, respectively. protein sequence homology analysis places the gene products within the growing family of luxri homologs. ahyr and asar are transcribed divergently from ahyi and asai, respectively, a ... | 1997 | 9286976 |
| pathogenicity of atypical aeromonas salmonicida in atlantic salmon compared with protease production. | the pathogenicity of extracellular products (ecps) from 24 atypical aeromonas salmonicida strains was studied with respect to: lethality in atlantic salmon, pathogenic effect in muscle, haemolytic activity, cytotoxicity in two fish cell lines and proteolytic activities. furthermore, the relationship between lethality of ecps and mortality caused by bacterial challenge was examined. correlation was demonstrated between the pathogenic properties and proteolytic activities of the ecps. cytolytic (g ... | 1997 | 9418019 |
| reappraisal of the effect of temperature on the growth kinetics of aeromonas salmonicida. | the effect of temperature (1-34 degrees c) on the maximum specific growth rate of aeromonas salmonicida could not be described by the classical growth models; for some strains, two optimal temperatures at 23 degrees c and 30 degrees c were observed, as well as an unexpected increase in the pseudolag time above 27 degrees c. this could be explained by the presence of two subsets, notably s-layer+ and s-layer- sub-populations. the a- cells had higher growth parameters (topt and mu opt) than the a+ ... | 1997 | 9418073 |
| further characterization of renibacterium salmoninarum extracellular products. | renibacterium salmoninarum, the agent of bacterial kidney disease in salmonids, releases high concentrations of extracellular protein in tissues of infected fish. the extracellular protein consists almost entirely of a 57-kda protein and derivatives of degradation and aggregation of the same molecule. the 57-kda protein and its derivatives were fractionated into defined ranges of molecular mass. separated fractions continued to produce degradation and aggregation products. one-dimensional electr ... | 1997 | 9480644 |
| identification and molecular characterization of two tandemly located flagellin genes from aeromonas salmonicida a449. | two tandemly located flagellin genes, flaa and flab, with 79% nucleotide sequence identity were identified in aeromonas salmonicida a449. the fla genes are conserved in typical and atypical strains of a. salmonicida, and they display significant divergence at the nucleotide level from the fla genes of the motile species aeromonas hydrophila and aeromonas veronii biotype sobria. flaa and flab encode unprocessed flagellins with predicted mrs of 32,351 and 32,056, respectively. when cloned under th ... | 1997 | 9286979 |