bluuebunny/crossref_metadata_2025 huggingface dataset:
Exotoxin‐induced consumptive coagulopathy in Atlantic salmon, Salmo salar L.: inhibitory effects of exogenous antithrombin and α2‐macroglobulin on Aeromonas salmonicida serine protease
Authors: SALTE R. , NORBERG K. , ØDEGAARD O. R. , ARNESEN J. A. , OLLI J. J.
Published: April 2006

Abstract. Consumptive coagulopathy was induced within 4 h in Atlantic salmon, Salmo salar L., by injecting purified serine protease from Aeromonas salmonicida into the dorsal aorta. Pretreatment with a bolus intravascular injection of (human) antithrombin (AT) or (bovine) α2‐macroglobulin (α2M) just prior to injection of the protease alleviated the in vivo pro‐coagulant effects of the enzyme, but could not hinder the development of consumptive coagulopathy. In fish receiving only saline as pretreatment, the coagulopathy was evident even after 28h, but the fish were not overtly sick. The addition of the exogenous inhibitors increased the fish's natural protection against the bacterial exotoxin, suggesting that both AT and α2M are of importance for the outcome of the pathologic process. Results further indicate that while AT in vivo was mainly directed against generated thrombin and activated coagulation factor X (FXa), α2M inhibited the protease directly.
A monoclonal antibody cross‐reactive with three salmonid herpesviruses
Authors: HAYASHI Y. , IZAWA H. , MIKAMI T. , KODAMA H.
Published: April 2006

Abstract. A monoclonal antibody cross‐reactive with strain H‐83 Oncorhynchus masou virus (OMV) and Herpesvirus salmonis has been prepared. Western blot analysis revealed that the monoclonal antibody, designated clo. 7, recognized the 16 000 (16K)‐polypeptide of these herpesviruses but not the polypeptides of infectious pancreatic necrosis virus or infectious haematopoietic necrosis virus. Clo. 7 showed neither neutralizing activity against strain H‐83 nor cytotoxicity to strain H‐83‐infected RTG‐2 cells in the presence of complement. The purified antigen, recognized by clo. 7, from strain H‐83 was a polypeptide with a molecular weight of 16K, and sensitive to proteolytic enzymes and sodium periodate, but not to neuraminidase and ethylether. The antigen was heat stable and stable at pH 5·0 – 9·0.
Fallowing of marine Atlantic salmon, Salmo salar L., farms as a method for the control of sea lice, Lepeophtheirus salmonis (Kroyer, 1837)
Authors: BRON J. E. , SOMMERVILLE C. , WOOTTEN R. , RAE G. H.
Published: April 2006

Abstract. Infections of Lepeophtheirus salmonis (Krøyer, 1837) and Caligus elongates Nordmann, 1832 were monitored over a 20‐month period on four marine Atlantic salmon, Salmo salar L., farms in Scotland. Three farms were fallowed between harvesting and restocking, and thus, contained only one year class of fish at a time. The fourth site was not fallowed and contained two year classes of fish. Results show that fallowing led to low numbers of L. salmonis on newly introduced fish for several months after stocking, with much less need to use chemotherapy. New fish in the non‐fallowed site became very rapidly infected with L. salmonis and required chemotherapy within 2 months of stocking. Fallowing did not appear to be effective in restricting the abundance of C. elongatus. Longer periods of fallowing were more effective in controlling lice numbers.
Partial purification and characterization of extracellular metalloproteases with caseinolytic, aminopeptidolytic and collagenolytic activities from Vibrio anguillarum
Authors: STENSVÅG K. , JØRGENSEN T. Ø. , HOFFMAN J. , HJELMELAND K. , BØGWALD J.
Published: April 2006

Abstract. Proteases produced by Vibrio anguillarum were isolated from culture supernatant by ultrafiltration, gel chromatography and ion exchange chromatography. The enzyme(s) were shown to be collagenolytic when assayed with native collagen substrates. In addition, the enzyme(s) hydrolysed azocasein, azocollagen, the collagenase substrate 4‐phenylazobenzyloxycarbonyl‐Pro‐Leu‐Gly‐Pro‐D‐Arg and the aminopeptidase substrate L‐Leu‐pNA effectively. Separation of the proteases by Mono Q ion exchange chromatography and native polyacrylamide gel electrophoresis revealed four distinct protein bands containing caseinase activity. However, only two of the bands showed aminopeptidase activity. The aminopeptidase activities could be separated from the caseinase activities by isoelectric focusing. Secreted proteases of different serotypcs of V. anguillarum showed a heterogeneous caseinolytic pattern. The molecular mass of the major enzyme was estimated at 35kDa as determined by its mobility on SDS‐polyacrylamide gels. Serine protease inhibitors like PMSF, TPCK, TLCK and benzamidine had no inhibitory effects on the proteolytic activity when tested with azocasein as substrate. However, the enzyme was strongly inhibited by metal chelators like EDTA and 1, 10‐phenanthroline. Also, normal salmon scrum and purified α2‐macroglobulin from salmon serum strongly inhibited the caseinolytic activity of the enzyme.
Environmental factors affecting outbreaks of winter saprolegniosis in channel catfish, Ictalurus punctatus (Rafinesque)
Authors: BLY J. E. , LAWSON L. A. , SZALAI A. J. , CLEM L. W.
Published: April 2006

Abstract. Previous studies have led to the development of a laboratory model for a disease termed ‘winter saprolegniosis’, locally referred to as ‘winter kill’, occurring in channel catfish, Ictalurus punctatus Rafinesque, raised in commercial ponds in the southeastern United States. In the laboratory, the onset of disease was routinely brought about by a combination of two related factors: (1) a rapid drop in water temperature which induces immunosuppression in catfish; and (2) maintenance of low water temperatures (∼10°C), which favour the proliferation of an ubiquitous fungus of the genus Saprolegnia to produce high levels of fungal zoospores (≥5 spores ml−1). In this study, two commercial catfish ponds were monitored for over one year to determine if the above factors occurred in the field and could be correlated with outbreaks of winter saprolegniosis. It was noted that passages of severe cold weather fronts were able to drop pond water temperatures ≥10°C within 24h and that such decreases in water temperature were associated with immunosuppression of the catfish in the ponds. Furthermore, when Saprolegnia sp. zoospore levels were ≥5 spores ml‐1, the immunocompromised catfish exhibited overt signs of winter saprolegniosis. If one of the factors implicated in the induction of disease was missing, fish in the ponds remained healthy. In addition, the onset of disease in the ponds appeared independent of pH and oxygen, total ammonia nitrogen and un‐ionized ammonia levels. Collectively, these field results confirm the laboratory‐based hypothesis concerning the aetiology of winter saprolegniosis in channel catfish.
A sensitive microbioassay for the detection of antibacterial agents in the aquatic environment
Authors: PEARSON M. , INGLIS V.
Published: April 2006

Abstract A sensitive microbioassay for the detection of antibacterials used in the therapy of farmed fishes is described. Three indicator organisms (Bacillus subtilis, Bacillus cereus and Escherichia coli) were evaluated for their sensitivity to seven antibacterial agents (Enrofloxacin, Sarafloxacin, Florfenicol, Cosumix, oxolinic acid, amoxycillin and oxytetracycline). The limits of detection using the microbioassay were compared with those for a conventional radial diffusion assay. The microbioassay was two to four times more sensitive for all antibacterials tested except for amoxycillin, where the end point was the same. The sensitivity of the microbioassay to the presence of oxytetracycline in sea water was evaluated using Bacillus cereus as an indicator organism. The results indicate that the microbioassay can be adapted for use with sea water samples if the samples are filtered before use.
Epidemiology of epizootic haematopoietic necrosis virus (EHNV) infection in farmed rainbow trout, Oncorhynchus mykiss (Walbaum): findings based on virus isolation, antigen capture ELISA and serology
Authors: WHITTINGTON R. J. , PHILBEY A. , REDDACLIFF G. L. , MACGOWN A. R.
Published: April 2006

Abstract. The epidemiology of epizootic haematopoietic necrosis virus (EHNV) infection was studied in farmed rainbow trout, Oncorhynchus mykiss (Walbaum). Estimates of mortality during five outbreaks on a commercial farm from 1986 to 1992 ranged from 0033 to 0.2% per day and total mortality did not exceed 3–4% in any outbreak. Affected fish were 0+ and less than 125 mm forklength. Clinical signs were non‐specific, and laboratory examination was required to confirm the diagnosis. At the height of the outbreak in 1992, EHNV was demonstrated by virus isolation and antigen capture ELISA in 89% of clinically affected fish and 51% of dead fish, while the prevalence of infection in apparently healthy in‐contact fish was 4%. Two and 4 months later the virus was not detected in a group of apparently healthy fish that had been affected earlier. Antibodies specific for EHNV were not found in rainbow trout from the infected farm; however, strong humoral responses were detected by ELISA in two immunized fish, indicating that the virus was immunogenic. These data suggested that EHNV was poorly infective but highly virulent in rainbow trout. Clinical EHNV infection was positively correlated with high rearing density and a low rate of water exchange, and therefore, with presumed poor water quality. Water temperature, which ranged from 11 to 17°C during outbreaks, did not appear to determine the incidence of clinical infection. EHNV infection in farmed rainbow trout was preceded by infection in free‐living redfin perch, Perca fluviatilis L., in the water catchment, but it was uncertain whether this represented the source of infection for rainbow trout.
Elevated serum levels of alpha foetoprotein (AFP)‐like immunoreactivity in rainbow trout, Oncorhynchus mykiss (Walbaum), with aflatoxin B1 induced hepatocellular carcinoma
Authors: SARCIONE E. J. , BLACK J. J.
Published: April 2006

Abstract. Alpha foetoprotein (AFP)‐like immunoreactivity was detected by double immunodiffusion in thesera of adult rainbow trout, Oncorhyachus mykiss (Walbaum) with histologically confirmed hepatocellular carcinoma experimentally induced in microinjection of embryos with aflatoxin B1 (AFB1). Partial characterization indicated that this AFP‐like immunoreactivity gave immunologic cross‐reaction of partial identity with human AFP. had alpha1 electrophorctic mobility, and an estimated molecular weight of 72kDa. Elevated serum AFP‐like immunoreactivity levels were also measured by RIA in seven out of eight adult rainbow trout with hepatocellular carcinoma, and in three out of 17 AFB1‐exposed trout without demonstrable grosws or microscopic evidence for hepatocellular neoplasms. No serum AFP‐like immunoreactivity was detected or measured in normal healthy age matched DMSO‐control rainbow trout. These data are consistent with the following conelusions: (1) AFP‐like immunoreactivity detected and measured in the sera of rainbow trout with hepaloecllular careinoma is an analogue to human AFP; and (2) the elevated serum AFP levels measured in adult rainbow trout wilh hepatocellular careinoma resrmble those found in humans with this same malignancy. These data further suggest that serum AFP measurements might be useful to confirm the appearance of hepatocellular carcinoma in experimental fish carcinogen‐assay systems, and to detect hepatocellular neoplasia in high‐risk wild fish populations exposed to carcinogenie pollutants.
Light and electron microscope observations on extrasporogonic and sporogonic stages of a myxosporean parasite of the genus Sphaerospora Thelohan, 1892 from Atlantic salmon, Salmo solar L., in Scotland
Authors: McGEORGE J. , SOMMERVILLE C. , WOOTTEN R.
Published: April 2006

Abstract. Juvenile Atlantic salmon from a number of freshwater hatcheries in Scotland were found to be infected by a myxosporean parasite of the genus Sphaerospora. Fish first became infected in June by extrasporogonic stages which could be found in the blood and kidney interstitium. These consisted of a primary cell containing one to over one hundred secondary cells. Some secondary cells contained one or two tertiary cells. Sporogony was disporous and occurred later in the kidney tubules. The development of both extrasporogonic and sporogonic stages was studied by light and transmission electron microscopy.
Florfenicol in Atlantic salmon, Salmo salar L.: field evaluation of efficacy against furunculosis in Norway
Authors: NORDMO R. , VARMA K. J. , SUTHERLAND I. H. , BROKKEN E. S.
Published: April 2006

Abstract. The efficacy of florfenicol in the control of natural outbreaks of furunculosis in Atlantic sallmon, Salmo salar L. was evaluated on five Norwegian farms during the summer of 1992. A total of 115 245 first‐ or second‐generation fish received florfenicol with feed at a dose rate of 10mgkg 1body weight daily for 10 consecutive days. Comparisons were made with similar pens of fish medicated with the preferred treatment for eaeh location. In the 10 days following introduction of therapy, all treatments were associated with a rapid decline in mortality caused by infection with Aeromonas salmonicida. Florfenicol‐medicated salmon had a lower specific mortality than those given oxolinie acid, flumequine or a trimethoprim and sulphadiazine eombination. No adverse reactions to treatment with florfenicol were observed.
Investigations into the transmission of Haemogregarina bigemina Laveran & Mesnil, 1901 (Apicomplexa: Adeleorina) between intertidal fishes in Portugal
Authors: DAVIES A. J. , EIRAS J. C. , AUSTIN R. T. E.
Published: April 2006

Abstract. During two summers in Portugal, intertidal fishes were captured with anaesthetic at four sites along the Portuguese Atlantic West Coast. They were examined for the blood parasite Haemogregarina bigemina, for other haematozoa, and for haematophagous eetoparasitcs. Haemogregarina bigemina was found only in biennies, Lipophrys pholis (L.) and Coryphoblennius galerita (L.), and infections in these fish were similar. No other haematozoa were detected. Ectoparasites found attached to biennies included haematophagous praniza larvae of the isopod Gnathia maxillaris and a single leech. Gametocytes like those of fish haemogregarines were found in the anterior hindgut of 25% of pranizae and one contained gametoeytes and stages resembling early oocysts. The leech showed none of these stages. It is concluded that gnathiid pranizae should be considered as possible vectors of H. bigemina in Portugal.
Growth inhibition of the salmon pathogen Vibrio ordalii by a siderophore produced by Vibrio anguillarum strain VL4355
Authors: PYBUS V. , LOUTIT M. W. , LAMONT I. L. , TAGG J. R.
Published: April 2006

Abstract. Thirty strains of V. anguillarum were tested for the production of inhibitory substances against closely‐related bacteria using the deferred antagonism test. Only one strain, Vibrio anguillarum VL4355, inhibited strains of V. ordalii and this effect was blocked by the addition of iron salts to the culture medium. Siderophore production was investigated for this strain. Results from bioassays suggested that strain VL4355 produced a siderophore related to anguibactin, the plasmid‐encoded phenolate siderophore produced by V. anguillarum strain 775. However, when plasmid DNA was compared for strains 775 and VL4355 the BamHI‐generated restriction profiles were different, although hybridization experiments indicated some homology. Using the chrome‐azurol sulphate assay to measure siderophore production, strain VL4355 yielded significantly higher values than other V. anguillarum strains. Amberlite XAD‐2 was used to produce concentrated siderophore preparations from strains VL4355 and 775. Both preparations were inhibitory to the growth of strains of V. ordalii, but not V. anguillarum, as were solutions of the iron chelator ethylenediamine‐di(o‐hydroxyphenylacetic acid). The difference in sensitivity to iron‐limiting conditions for V. ordalii and V. anguillarum, coupled with the inability of V. ordalii to utilize ferric‐anguibactin, could reflect different mechanisms of iron uptake for these two organisms.
Survival of the fish pathogen Aeromonas salmonicida in the marine environment
Authors: EFFENDI I. , AUSTIN B.
Published: April 2006

Abstract. The fate of the fish pathogen Aeromonas salmonicida in the marine environment was examined by culture, epifluorcscence microscopy, the indirect fluorescent antibody technique (1FAT), direct viable counts (= Kogure technique) and the assessment of respiratory activity by the reduction of tetrazolium compounds to coloured formazans. In laboratory‐ based systems containing sediment, water, algae and invertebrates, cells of A. salmonicida were observed microscopically after plate counts on tryptone soya agar declined to zero. Survival was maximal at a salinity of 25%o, and in wood and sediment, notably mud, rather than the water column.
Investigation of outbreaks of a novel disease, ‘Sleepy Grouper Disease’, affecting the brown‐spotted grouper, Epinephelus tauvina Forskal
Authors: CHUA F. H. C. , NG M. L. , NG K. L. , LOO J. J. , WEE J. Y.
Published: April 2006

Abstract. A novel disease affecting the brown‐spotted grouper, Epinephelus tauvina Forskal, described here as Sleepy Grouper Disease1 (SGD), resulted in significant economic losses in some Singaporean marine net‐cage farms from April to August 1992. Investigations suggested that the aetiological agent was a virus, probably introduced with imported groupers. The virus was provisionally identified as an iridovirus on morphological evidence. The disease caused extreme lethargy in affected fish with few visible external signs. Mortalities either occurred gradually over the week from onset of clinical signs, or over a shorter period and in large numbers if fish were stressed. Consistent tissue changes were seen by light microscopy in the spleen, heart and kidney of affected fish. Electron microscopy showed viral particles associated with damage to cell organelles. In an experimental infection, apparently healthy fish cohabiting with an infected fish developed similar lesions and died. The significance of SGD in grouper culture is discussed.
Histopathological and ecological aspects of Henneguya and Myxobolus (Myxosporea) infections in Acanthopagrus australis (Günther) (Pisces: Sparidae) from Moreton Bay, Australia
Authors: ROUBAL F. R.
Published: April 2006

Abstract. Sporulated plasmodia of Henneguya sp. infected the gill filaments, interhemibranch septum, gut and other microhabitats of Acanthopagrus australis in Moreton Bay, southern Queensland, whereas Myxobolus sp. infected only the gut. There was usually no inflammatory response, but some plasmodia in the gill filaments were associated with a granulomatous, predominantly lymphoid, response that was not determined by either parasite maturity, or sex and size of fish or season. There was a microhabitat shift in branchial Henneguya infection from predominantly gill filament in juvenile bream to gill septum in older fish. The highest prevalences of Henneguya were in the southern part of Moreton Bay, but trends in seasonal infection and prevalences in relation to size and sex of fish were similar in the western and southern parts of the bay. This suggested a widespread distribution of the putative annelid alternate host in Moreton Bay, with highest densities in the southern part. Myxobolus infection was most prevalent in young male fish at the winter spawning grounds on eastern surf bars.
Intestinal absorption of immunomodulatory laminaran and derivatives in Atlantic salmon, Salmo salar L.
Authors: DALMO R. A. , INGEBRIGTSEN K. , HORSBERG T. E. , SELJELID R.
Published: April 2006

Abstract. Radiolabelled (125I, 3H) immunomodulatory laminaran (isolated from Laminaria hyperborea), a β(1,6)‐branched β(1,3)‐D‐glucan and different radiolabelled sulphated analogues of laminaran were administered peranally to Atlantic salmon, Salmo salar L. Intestinal absorption and tissue distribution were examined by means of radioactive tracer techniques. The intestinal uptake was highest with native laminaran and laminaran with a low degree of sulphatation, while highly sulphated laminarans were poorly absorbed. The tissue distribution analysis revealed high amounts of radiolabelled compound in the liver, and anterior and posterior kidney, whereas the spleen contained low amounts. Peak serum and organ concentrations were reached about 30 min after administration. The results were confirmed by autoradiography of tissue sections from salmon after peranal administration of radiolabelled laminaran. Finally, the peranal administration of fluorescence labelled laminaran revealed epithelial supranuclear fluorescent vacuoles containing laminaran. It is concluded that native laminaran and slightly sulphated laminaran are absorbed from the posterior intestine and that they are distributed to tissues rich in immunocompetent cells. Thus, these compounds may have potential as immunomodulatory feed additives.
Extracellular glycerophospholipid:cholesterol acyltransferase from Aeromonas salmonicida: activation by serine protease
Authors: EGGSET G. , BJØRNSDOTTIR R. , LEIFSON R. MCQUEEN , ARNESEN J. A. , COUCHERON D. H. , JØRGENSEN T. Ø.
Published: April 2006

Abstract. Extracellular hacmolytic activities of Aeromonas salmonicida ssp. salmonicida to salmon red blood cells were shown to be due to different forms of the membrane‐active enzyme glyccrophospholipidrcholcstcrol acyltransferase (GCAT). About 10% of the total haemolytic activity was due to a high molecular mass complex of LPS and GCAT (mol. mass >1000kDa), containing 35–50% neutral sugars and 1.5–2.0% protein. Some haemolytic activity (30–40% of total), corresponding to 50–70kDa by gel filtration, also contained GCAT‐activity and may represent aggregated forms of GCAT. However, about 50% or more of the haemolytie activity was due to a protein of 26kDa free GCAT. Rabbit antibodies to GCAT neutralized the hacmolytic activity of both GCAT and GCAT‐LPS. A transposon‐produccd serinc protease negative mutant of the same A. salmonicida strain showed reduced haemolytic activity. The mutant produced a 38‐kDa GCAT proform of low hacmolytic activity. The proform was processed by autogenous scrinc protease to a highly hacmolytic 26‐kDa molecule with pl 6.3, similar to GCAT of the parent strain. The weakly haemolytic GCAT‐LPS analogue of the mutant strain did not contain detectable amounts of the 26‐kDa molecule and was not activated by proteases.
Presence of infectious salmon anaemia virus (ISAV) in tissues of Atlantic salmon, Salmo salar L., collected during three separate outbreaks of the disease
Authors: NYLUND A. , HOVLAND T. , WATANABE K. , ENDRESEN C.
Published: April 2006

Abstract. Infectious salmon anaemia (ISA) is a viral disease of farmed Atlantic salmon, Salmo salar L., in Norway. The enveloped virus particles (100nm) believed to be the causative agent of the disease have been observed budding from endothelial cells in heart blood vessels. However, it is not known if the virus propagates in endothelial cells in all tissues/organs, if other target cells exist or if material collected from different salmon farms with natural outbreaks of ISA contain the same virus particles. Salmon smolts from three hatcheries with no history of disease were taken into the laboratory and experimentally challenged with ISA collected from Atlantic salmon during natural outbreaks of the disease in three different fish farms outside Bergen. Norway. Tissues for TEM studies were Collected from: (1) organs that showed clinical signs of ISA (i.e. used in the diagnosis of the disease); (2) tissues believed to be important in transmission of the virus (integument, kidney, urinary bladder, gut and somatic muscle); and (3) hormone‐producing tissues (pituitary gland, saccus vasculosus, thymus, thyroid, ultimobranehial gland, gonad, head kidney, heart and ventral aorta). The same virus as that believed to be the causative agent of ISA was found in all tissues examined from the challenged fish, i.e. a multiorgan infection with the same virus present in salmon from all three fish farms. The virus particles are about 100 nm in diameter, consisting of a slightly pleomorphic unit membrane envelope within which are a number of granules about 10–12nm in diameter. The granules seemed to be arranged in two concentric circles (spheres). The virus was seen budding from the surface of endothelial cells in blood vessels/sinus only. However, the virus was found intracellularly in both endothelial cells and in leucocytes.
Multiplication of infectious pancreatic necrosis virus (IPNV) in head kidney and blood leucocytes isolated from Atlantic salmon, Salmo salar L.
Authors: JOHANSEN L.‐H. , SOMMER A.‐I.
Published: April 2006

Abstract. Blood and head kidney (HK) leucocytes were isolated from Atlantic salmon, Salmo salar L., carrying infectious pancreatic necrosis virus (IPNV), and the cells were separated into adherent and non‐adherent populations. Significant increases in both intra‐ and extracellular IPNV titres, and in the number of IPNV‐positive fluorescent cells were detected in adherent HK leucocytes during 7 days in culture, and demonstrated that IPNV multiplied in these cells. Infectious virus was not detected in culture medium collected from blood leucoeytes, and only occasionally, in very low titres, from non‐adherent HK leucocytes. No IPNV‐positive fluorescent cells were detected in these cell populations. IPNV infection of adherent leucocytes isolated from non‐carrier fish indicated that adherent blood leucocytes (mainly monocytes) could become productively infected in vitro, but to a lesser degree than adherent HK leucocytes (mainly macrophages). The present results suggest a major role for adherent HK leucocytes in maintaining the IPNV carder state in Atlantic salmon.
Delivery of quinolone antibacterials to turbot, Scophthalmus maximus (L.), via bioencapsulation: quantification and efficacy trial
Authors: DUIS K. , HAMMER C. , BEVERIDGE M. C. M. , INGLIS V. , BRAUM E.
Published: April 2006

Abstract. The incorporation of the quinolone antibacterials oxolinic acid and sarafloxacin into Artemia fransciscana and subsequently into turbot, Scophthalmus maximus (L.), was quantified, and the therapeutic efficacy of the bioencapsulated drugs against challenge with Vibrio anguillarum 8587 was investigated. Five‐week‐old turbot were fed for 10 days with Artemia enriched with either oxolinic acid or sarafloxacin. Therapeutic concentrations were reached with both drugs (11.8 μg oxolinic acid per gram fresh weight: 1.8 μg sarafloxacin per gram fresh weight). Both treatments proved effective against challenge, with V. anguillarum‐specific mortality rates of 6 and 14% in the oxolinic acid and sarafloxacin treated groups, respectively, compared with 75% in the infected control. However, incorporation of the drug by brine shrimp was extremely low (<1%), and therefore, bioencapsulation cannot be considered as an appropriate method to reduce impact on the environment.
Residues of [14C]‐malachite green in eggs and fry of rainbow trout, Oncorhynchus mykiss (Walbaum), after treatment of eggs
Authors: MEINERTZ J. R. , STEHLY G. R. , GINGERICH W. H. , ALLEN J. L.
Published: April 2006

Abstract. Rainbow trout, Oncorhynchus mykiss (Walbaum), eggs were exposed to [methane‐14C] malachite green chloride on day 0 and on every third day thereafter through day 24, with a final treatment administered to fry on day 31. Eggs or fry were sampled before each treatment, and at selected times from day 31 to day 59. Malachite green equivalence in eggs and fry was determined by sample oxidation and liquid scintillation counting. Total malachite green residues increased throughout the exposure period to 0.271 ± 0.042 μg g−1 (x̄± SD) on day 31. Residues declined to 0.055 ± 0.011 μg g−1 on day 59. The depuration phase declined monoexponentially with a half‐life of 13.3 days for the absolute amount (μg sample−1) and a half‐life of 9.7 days for the concentration of malachite green residues (μg g−1). Growth dilution accounted for the 25% increase in the elimination (9.7 days) of malachite green residues. Extracts from treated eggs and fry were analysed by reversed‐phase liquid chromatography. Three peaks were resolved in treated eggs: chromatic malachite green, leuco malachite green and an unknown polar metabolite. Only two peaks were resolved in the fry: leuco malachite green and the unknown polar metabolite. The most prominent residue in all samples was leuco malachite green.
Impact of a pathogenic haemoflagellate, Cryptobia salmositica Katz, on the metabolism and swimming performance of rainbow trout, Oncorhynchus mykiss (Walbaum)
Authors: KUMARAGURU A. K. , BEAMISH F. W. H. , WOO P. T. K.
Published: April 2006

Abstract. Oxygen consumption of juvenile rainbow trout (5 g at 13°C) at moderate swimming speeds did not change significantly when infected with Cryptobia salmositica. However, significant reductions of as much as 44% of the maximum aerobic scope for activity and 24% of the critical swimming speed were observed when the parasitaemia reached a maximum of 57.6 × 106 ml−1 fish blood at 3 weeks post‐ infection. Blood haematocrit was significantly reduced from the initial 34.1 to 19.7% at 4 weeks post‐ infection, probably as a result of haemolysis by the parasite. The destruction of red blood cells clearly led to lower oxygen carrying capacity, and reduced respiratory and swimming performance.
Detection of Penaeus monodon‐type baculovirus (MBV) infection in Penaeus monodon Fabricius by in situ hybridization
Authors: LU C. C. , TANG K. F. J. , KOU G. H. , CHEN S. N.
Published: April 2006

Abstract. A digoxigenin‐labelled DNA probe was used for in situ detection of the Penaeus monodon‐type baculovirus (MBV) derived from cloned MBV polyhedrin genome in cultured Penaeus monodon Fabricius. First, the specificity of the probe against MBV DNA with dot blot hybridization analysis was verified. This probe indicated that cloned MBV polyhedrin fragment can be used as an MBV‐specific probe. This was then used to microscopically examine sections of MBV‐infected tissues for a blue‐purple precipitate indicative of a positive reaction for MBV. MBV‐positive cells were located only in the epithelium of the hepatopancreatic tubules and of the midgut. Furthermore, comparison of the susceptibility to MBV infection among several life‐stages of the shrimp showed that the MBV genome was found in the zoea, mysis, post‐larva, and adult stages, whereas MBV DNA was not detected in either eggs or nauplii. The results were quantified from in situ hybridization with an image analyser to compare the degree of cell infection among groups of cultured P. monodon collected from various farms in Taiwan.
Immune responses of channel catfish, Ictalurus punctatus (Rafinesque), after oral or intraperitoneal vaccination with particulate or soluble Edwardsiella ictaluri antigen
Authors: AINSWORTH A. J. , RICE C. D. , XUE L.
Published: April 2006

Abstract. Groups of channel catfish, Ictalurus punctatus (Rafinesque). were administered Edwardsiella ictaluri twice in the form of whole outer membrane proteins (OMP) or heat‐inactivated whole bacteria (IWB) orally or IWB intraperitoneally. Antibody titres and lysozyme concentrations were determined in serum, mucus, gut contents and gut washings taken 7, 14, 21 and 28 days after the second antigen administration. Bacterial killing by anterior kidney neutrophils was determined 7, 14 and 21 days after the second antigen administration. Enhanced killing of tumour targets by nonspecific cytotoxic cells (NCC) was determined 7 days after the second antigen administration. Serum antibody titres of all treatment groups were significantly increased above those of the control group throughout all sampling periods. Fish receiving oral administration of OMP or IWB exhibited maximum serum antibody titres on day 21 or 28. Antibody titres were also detected in mucus, gut washings and gut contents, but did not reach the level of those in the serum. Bacterial killing was significantly increased only on day 7, and could not be correlated to antibody titre or lysozyme concentration. Bacterial killing was found to be the result of a heat‐labile serum factor. NCC activity of fish vaccinated with IWB orally was significantly higher than that of fish vaccinated with OMP orally or controls. Although intraperitoneal vaccination consistently produces higher titre antisera, the results of this study support the idea that oral vaccination can induce antibody systhesis.
Immunization of adult brook trout, Salvelinus fontinalis (Mitchill), fails to prevent the infectious pancreatic necrosis virus (IPNV) carrier state
Authors: SCOTLAND L. M. , DOBOS P. , STEVENSON R. M. W.
Published: April 2006

Abstract. Adult brook trout, Salvelinus fontinalis (Mitchill), mounted a strong humoral immune response after injection with inactivated infectious pancreatic necrosis virus (IPNV) in Freund's complete adjuvant (FCA). However, this immunization did not prevent the fish from becoming IPNV carriers. After an injection challenge with virulent IPNV, the immunized and control fish (FCA or water) shed virus in the faeces and reproductive products and had IPNV‐infected leucocytes and visceral organs. Initially, from 1 to 3 weeks post‐challenge (wpc), immunized fish had a lower prevalence of infection and virus titres in the plasma, and fewer infected leucocytes than the control fish. Immunization did not prevent the eventual infection of the leucocytes; over 75% of the immunized and control fish had leucocyte‐associated viraemia from 6 to 15 wpc. When the organs were tested at 15 wpc, the immunized fish showed fewer infected organs per fish, and a lower prevalence of infection and virus titres in individual organs than the control fish, but these differences were not significant. Immunized male and female fish shed IPNV in the reproductive products, suggesting that immunization of adult fish would not prevent vertical transmission of IPNV to progeny.
Serum resistance as a good indicator for virulence in Aeromonas hydrophila strains isolated from diseased fish in South‐East Asia
Authors: LEUNG K. Y. , YEAP I. V. , LAM T. J. , SIN Y. M.
Published: April 2006

Abstract. Aeromonas hydrophila strains isolated from diseased fish in South‐East Asia were studied for their virulence in naive tilapia, Oreochrommis aureus (Steindachner), and blue gourami, Trichogaster trichopterus (Pallas). Five of the most virulent strains used in this study shared a common resistance to the killing effect of naive fish serum. Other factors such as lack of autoagglutination in 0.2% acriflavine, instability after boiling, production of an S‐layer, and proteases and haemolysins did not correlate well with virulence. In addition, serotyping could not group all the virulent strains. Therefore, serum resistance is considered as a good indicator for screening virulence of A. hydrophila strains isolated from diseased fish in South‐East Asia.
Experiments with growth of the eel trypanosome, Trypanosoma granulosum Laveran & Mesnil, 1902, in semi‐defined and defined media
Authors: DAVIES A. J. , MASTRI C. , THORBORN D. E. , MACKINTOSH D.
Published: April 2006

Abstract. Growth of the eel trypanosome, Trypanosoma granulosum, was attempted in five semi‐defined and three defined media. Growth was poor in four semi‐defined and two defined media, but one semi‐defined medium, a modified version of SDM‐79 without MEM F‐14, supported good growth of the trypanosome. In this medium, doubling time was between 1 and 2 days, over 90% of organisms seen in culture after 6 days were trypomastigotes, and 1.8 × 0.1 × 107 trypanosomes ml−1 was achieved in 7 days. When foetal calf serum from the modified SDM‐79 was substituted with insulin to create a fully defined medium, a modest but significant increase in cell numbers occurred compared with controls. In vitro experiments with D, L‐alpha‐difluoromethylomithine (DFMO) showed morphological changes leading to destruction of the trypanosome with increasing concentrations of the drug. A 50‐mM concentration of DFMO inhibited growth by more than 90%, and the IC50 was found to be 16 × 2 mM.
Development of a diagnostic test for Mikrocytos roughleyi, the aetiological agent of Australian winter mortality of the commercial rock oyster, Saccostrea commercialis (Iredale & Roughley)
Authors: ADLARD R. D. , LESTER R. J. G.
Published: April 2006

Abstract. Diagnosis and epidemiology of Mikrocytos roughleyi, the aetiological agent of Australian winter mortality of the rock oyster, Saccostrea commercialis (lredale & Roughley), has been hampered by the small size of the pathogen and the low intensity of natural infections. Inoculation of experimental oysters with filtered, unpurified tissue homogenate from oysters infected naturally produced experimental infections after 22 weeks but hyperinfection was not successful. DNA was extracted from naturally infected, experimentally infected and uninfected oysters, then oligonucleotide primers were used in polymerase chain reactions to provide the basis for a molecular bioassay. One pair of primers produced an amplicon of 680 base pairs in length that was correlated directly to the presence of M. roughleyi in oyster tissues. The assay was able to detect a single organism of M. roughleyi in 400 host cells.
Some biochemical properties and antibiotic sensitivities of Pasteurella piscidda isolated in Greece and comparison with strains from Japan, France and Italy
Authors: BAKOPOULOS V. , ADAMS A. , RICHARDS R. H.
Published: April 2006

Abstract The biochemical properties and antibiotic sensitivity patterns of 13 Pasteurella piscicida isolates from Greece are described and compared with 10 Japanese and five European (Italian and French) isolates. Morphologically and biochemically, all isolates of P. piscidda tested were nearly identical and only minor differences could be detected with reference to the level of acid production from sugars (especially from glucose). Greek, Italian and French isolates showed similar antibiotic sensitivity patterns, being resistant to erythromycin, kanamycin and streptomycin, and sensitive to most of the other antibiotics tested. Resistance was also demonstrated for some isolates towards the potentiated sulphonamides. The Japanese isolates appeared to be resistant to a larger range of antibiotics including erythromycin, kanamycin, streptomycin, oxolinic acid, oxytetracycline and chloramphenicol. Multiple resistance of Japanese strains was also noted. These results are discussed in the light of future measures for the control of pasteurellosis.
Experiments on the infection dynamics of Caligus epidemicus (Copepoda: Caligidae) on the small marine fish, Ambassis marianus (Günther)
Authors: HALLETT S. L. , ROUBAL F. R.
Published: April 2006

Abstract Copepodids of Caligus epidemicus survived for up to 7, 8 and 5 days at 19, 22 and 26 °C, respectively, without food. Activity was high up to 3 days and then declined, but 3‐ or 4‐day‐old copepodids were more infective than younger copepodids, suggesting an initial dispersal phase. Although the success of attachment to perchlets, Ambassis marianus, was higher in small volumes of water, there was no statistically significant association between water volume (1, 4, 60 and 2001) and success of attachment. Most copepodids and early chalimus stages in single and multiple infections were attached to the pectoral fins, but did not settle preferentially beside other copepodids on the skin of the host. The parasite was overdispersed (negative binomial distribution) when groups of fish were exposed to 100 copepodids. Perchlets were killed when exposed to large numbers of copepodids and adult C. epidemicus, but survived for at least 5 days after exposure to 25 or fewer copepodids and five or fewer adults (although not necessarily all attached).
Description of Myxobolus bulbocordis sp. nov. (Myxosporea: Myxobolidae) from the heart of Barbus sharpeyi(Günther) and histopathological changes produced by the parasite
Authors: Masoumian M , Baska F , Malnár K
Published: April 2006

A new myxosporean, Myxobolus bulbocordis sp. nov., has been found in the heart of a Mesopotamian fish, Barbus sharpeyi (Günther), in rivers in Southwest Iran. Cysts containing matured spores were located on the serosa of the atrium cordis, bulbus arteriosus, larger gill arteries and inside the wall of the bulbus. The species showed an affinity to connective tissue cells and was never associated with the muscles. Mature cysts were surrounded by a connective tissue capsule composed of two to three layers. Spores in disrupted cysts were infiltrated by epithelioid cells and macrophages. The spores found in Barbus sharpeyi differed in size and morphology from species known from other barbels.
Alcohol‐soluble components in soybeans cause morphological changes in the distal intestine of Atlantic salmon, Salmo salar L.
Authors: van den Ingh T S G A M , Olli J J , Krogdahl Å
Published: April 2006

Standard soybean meal, heat treated to differing degrees and containing varying levels of soybean lectin and trypsin inhibitor, was used to study the effect of soybean‐containing diets on the morphology of the distal intestine in Atlantic salmon, Salmo salar L. A reference diet based on fish meal and a fish meal diet mixed with an alcohol extract of soybean meal were used. The fish (145 g) were kept in 27 m3 net pens (200 fish per pen) in sea water with an average temperature of 11 °C for 12 weeks. Whereas a normal morphology of the distal intestine was seen in the fish fed the reference diet, all soybean diets caused alterations in the distal intestine irrespective of heat treatment. Similar changes were observed with the diet which had added alcohol solubles. It is concluded that alcohol‐soluble components in the soybeans are responsible for the observed changes. It cannot be determined which of the soybean antinutrients is causing the alterations from the present study. Oligosaccharides and saponines are possible candidates. However, the possibility that unknown antinutrients are affecting the salmon intestine should not be overlooked.
Lagenidium callinectes (Couch, 1942) infection and its control in cultured larval Indian tiger prawn, Penaeus monodon Fabricius
Authors: Ramasamy P , Rajan P R , Jayakumar R , Rani S , Brennan G P
Published: April 2006

A mycosis in larval tiger prawn, Penaeus monodon Fabricius, is described for the first time from India. The hyphae of Lagenidium callinectes are contorted, irregularly branched, sparingly septate, and contain a cell wall and membrane, vacuoles, mito chondria, ribosomes, small and large vesicles, and Woronin bodies. The spores occur singly or in pairs. The fungal mycelium may either invade and embed itself in the tissues, or alternatively, replace all the muscle tissues of the infected larval P. monodon. Fungus infected, untreated populations of nauplii, zoea and myksis exhibited mortalities of 5.33 ± 0.55%, 24.68 ± 4.58% and 47.89 ± 0.27%, respectively. A 0.5 ppm treatment with trifluralin significantly reduced the mortality of infected larval populations (i.e. 1.1% nauplii, 3.28% zoea and 5.21% myksis mortality). Lagenidium sp. exhibited growth in potato dextrose agar medium and in Sabouraud's agar at 28 °C.
Characterization of a monoclonal antibody against the 47‐ kDa antigen of Cryptobia salmositica Katz and its use in an antigen‐capture enzyme‐linked immunosorbent assay for detection of parasite antigen in infected rainbow trout, Oncorhynchus mykiss (Walbaum)
Authors: Verity C K , Woo P T K
Published: April 2006

A monoclonal antibody (designated MAb‐007) was produced against the pathogenic haemoflagellate Cryptobia salmositica Katz. This IgG3 antibody recognized the 47‐kDa antigenic polypeptide of C. salmositica (SDS‐PAGE and Western immuno‐blotting). The antibody did not agglutinate live parasites, and there was no change in the staining intensity of the 47‐kDa band on Western immunoblots after immunoabsorption of MAb‐007 with live intact parasites. The 47‐kDa antigen recognized by MAb‐007 was localized in the cytoplasm of the parasite (immunogold labelling and electron microscopy). The monoclonal antibody cross‐ reacted with the 47‐kDa polypeptides of C. bullocki Srrout and C. catostomi Bower & Woo. It was used in an antigen‐capture ELISA for the detection of parasite antigen in the plasma of rainbow trout inoculated with the parasite, or with an attenuated vaccine strain of C. salmositica. All pre‐infection plasma were negative while all infected fish with detectable parasitaemias were positive for antigen at 1–9 weeks after infection. Parasite antigen was even detected in vaccinated fish that were negative for parasites using the wet mount microscopic technique. The antigen‐capture ELISA detected C, salmositica antigen in whole cell lysate preparations at concentrations as low as 0.5 μg ml‐1. Fifty microlitres of fish plasma was required in the antigen‐capture ELISA, and the use of a plate reader and 96‐well plates facilitated rapid analysis of a large number of plasma samples. The sensitivity of the assay makes it a potentially useful tool for detection of Cryptobia infections.
The histopathology of carp, Cyprinus carpio L., exposed to microcystins by gavage, immersion and intraperitoneal administration
Authors: Carbis C R , Rawlin G T , Mitchell G F , Anderson J W , McCauley I
Published: April 2006

Carp liver, gills, intestine, kidneys, heart and spleen were studied by histology after the fish were exposed to microcystins by gavage, immersion and intraperitoneal administration. Intraperitoneal inoculation with microcystins caused necrosis or dose‐ dependent degeneration in the liver, gills and kidneys. Gavaging with microcystins caused changes in the histopathology of the liver and gills. Cellular degeneration and necrosis occurred in the liver, gills and kidneys when carp were introduced to a tank containing 1.7 μg ml−1 of microcystins. Lesions were not observed in the heart, spleen or intestines from any of the treated carp. Microcystins administered by intraperitoneal injection at a concentration of 50 μg kg−1 were lethal to all fish within 8 h, while gavaging with 250 μg kg−1 of microcystins caused minimal damage in the tissues studied.
Histopathology of experimental Streptococcus sp. infection in tilapia, Oroochromis niloticus (L.), and channel catfish, Ictafurus punctatus (Ratinesque)
Authors: Chang P H , Plumb J A
Published: April 2006

Nile tilapia, Oreochromis niloticus (L.), and channel catfish, Ictalurus punctatus (Rafinesque), were experimentally infected by immersion with three isolates (Lake, DL8O5 and MS91452) of Streptococcus sp. from diseased fish. To enhance infection, the lateral body surface of each fish was scraped prior to bacterial exposure. The Lake and DL8O5 isolates caused exophthalmia, ocular opacity and ocular haemorrhage in some tilapia. Histopathology of these fish revealed; meningitis; polyserositis of heart, liver, spleen, ovary and kidney; splenitis; ovaritis; and myocarditis. Isolate MS91452 induced only mild granulomas in spleen, kidney and ovary of tilapia. The Lake and DL8O5 isolates induced endophthalitis, Channel catfish infected with the Lake and DL805 isolates developed similar eye lesions to tilapia. Histologic lesions caused by all three isolates in channel catfish consisted of meningoencephalitis, mild myocarditis, splenitis and ovaritis, but these lesions were not as severe as in Nile tilapia.