bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of a discontinuous Percoll gradient technique for the separation of channel catfish, Ictalurus punctatus (Rafinesque), peripheral blood leucocytes
Authors: WATERSTRAT P. R. , AINSWORTH A. J. , CAPLEY G.
Published: April 2006

Abstract The use of a discontinuous density Percoll gradient in the separation of channel catfish peripheral blood leucocytes is described. The procedure yielded fractions enriched in monocytes and lymphocytes at the 1·060–1·065 g/ml interface, lymphocytes at the 1·065–1·070 g/ml interface, and neutrophils at the 1·070–1·080 g/ml interface. Cell purities among fractions ranged from 14·4–51·6% for monocytes, 61·4–72·8% for lymphocytes, and 60·4–79·2% for neutrophils. Factors influencing the outcome of the separation procedure include the use of pooled blood samples and calcium‐ magnesium‐free salt solutions.
Vaccine‐induced protective immunity against Aeromonas salmonicida tested in experimental carp erythrodermatitis
Authors: EVENBERG D. , de GRAAFF P. , LUGTENBERG B. , Van MUISWINKEL W. B.
Published: April 2006

Abstract The development and applicability of a dose‐controlled experimental infection with atypical Aeromonas salmonicida in carp is described. The proliferation and clinical manifestations of experimentally induced carp erythrodermatitis mimicked a natural infection. An in‐vivo assay was used to evaluate the lethal properties of cell‐free culture supernatants and a simple serum‐free growth medium was devised for maintaining the virulence of the challenge strain. Depending on the inoculation dose, a sublethal (chronic) to a lethal (acute) infection could be induced, and a dose‐response relation was observed between A. salmonicida inoculum size and carp mortality. The dose‐controlled experimental infection was used as a challenge test for laboratory evaluation of the efficacy of potential vaccine candidates. The vaccine candidates tested, a cell envelope preparation, purified lipopolysaccharide and purified A‐layer (ACE) protein showed no protection or only a feeble one at the best, while formalinized whole cells showed a consistent but only moderate protection. In contrast, when concentrated, detoxified culture supernatant was used, the carp were protected against a subsequent lethal challenge. These observations indicate that immunity against A. salmonicida extracellular products is of prime importance.
Histopathology, electron microscopy and isolation of channel catfish virus in experimentally infected European catfish, Silurus glanis L.
Authors: CHUMNONGSITATHUM B. , PLUMB J. A. , HILGE V.
Published: April 2006

Abstract Two groups of European catfish, Silurus glanis L., fingerlings were infected with channel catfish virus (CCV) by either intraperitoneal injection with 105 TCID50 of CCV, or bathing in water containing 105 TCID50 of CCV per 1·0 ml. The virus was isolated from spleen, intestine and brain of CCV‐injected fish at day 1 and the titres ranged from 102·1 to 103·3 TCID50/g. However, the tissue distribution of CCV was irregular and no virus was isolated after day 3 post‐exposure. In CCV‐bathed fish, the virus was isolated only from the liver of one specimen at day 3 post‐exposure. No clinical signs of CCV disease developed in any of the fish. Specimens in each regime from all sampling periods showed some minor histopathological changes, but there were no differences between treatments. Lesions included oedema and focal haemorrhage in the liver and the spleen was congested. Electron micrographs of tissue samples showed the presence of a few virus particles around the nuclei of kidney, spleen and intestinal cells, and in or around a myelinated nerve within the optic lobes of infected fish during the first 4 days of infection.
Use of an indirect enzyme‐linked immunosorbent assay (elisa) in the detection of channel catfish, Ictalurus punctatus (Rafinesque), antibodies to Edwardsiella ictaluri
Authors: WATERSTRAT P. , AINSWORTH J. , CAPLEY G.
Published: April 2006

Abstract. The use of an indirect enzyme‐linked immunosorbent assay (elisa) for the detection of channel catfish antibody to Edwardsiella ictaluri is described. Changes in agglutination titre in fish immunized with Edwardsiella ictaluri heat killed whole bacterins or lipopolysaccharides were reflected by corresponding changes in elisa readings. Relatively high correlations were observed among elisa OD readings, computed elisa titres and corresponding agglutination titres.
Hepatocellular carcinoma and fatty infiltration in the Atlantic tomcod, Microgadus tomcod (Walbaum)
Authors: CORMIER S. M. , RACINE R. N. , SMITH C. E. , DEY W. P. , PECK T. H.
Published: April 2006

Abstract. The livers of Atlantic tomcod, Microgadus tomcod (Walbaum), from the Hudson and Pawcatuck Rivers were evaluated histologically and described using paraffin and plastic sections. Fatty infiltration, basophilic foci, areas of cellular alteration and hepatocellular carcinoma were widespread in Hudson River samples. In fact, no truly normal tissues were found. Pawcatuck samples had variable levels of lipid and a low prevalence of other alterations. Evaluation of the histological evidence suggests that hepatocellular carcinoma in Hudson River tomcod results from multiple DNA lesions and that areas of cellular alteration give rise to the larger, more invasive form of hepatocellular carcinoma. Glutaraldehyde and OsO4 fixed livers were used to determine differences in cell types and lipid levels. Pawcatuck samples possessed hepatocytes and dark cells forming the parenchymal tissue, whereas Hudson samples lacked dark cells. Hepatic lipid levels were significantly higher in Hudson River fish than in Pawcatuck fish, 36·3 and 11·0% respectively. The elevated hepatic lipid levels in Hudson River tomcod may represent a metabolic response to detoxification.
Cell‐mediated immunity of the eel, Anguilla japonica (Temminck & Schlegel), as measured by the migration inhibition test
Authors: SONG Y. ‐L. , LIN T. , KOU G. ‐H.
Published: April 2006

Abstract. Sensitized lymphocytes isolated from the immunized eel, Anguilla japonica, upon interaction with the antigens in vitro, elaborated into the medium a soluble factor which was capable of inhibiting the migration of peritoneal exudate cells harvested from guinea pigs. Production of migration inhibition factor (MIF) was greatest to the specific antigen although there was also some nonspecific release. The elaboration of MIF from the sensitized lymphocytes occurred from the third day after immunization of eels and was detectable until day 106. The inhibitory activity from the blood appeared to persist over a longer period compared to that from the spleen and the anterior kidney. The inhibitory activity, however, was diminished by starvation of the immunized eels.
Salmonid whirling disease: myxosporean and actinosporean stages cross‐react in direct fluorescent antibody test
Authors: MARKIW M. E.
Published: April 2006

Abstract. Serologic relatedness of the two life stages of the salmonid whirling disease parasite Myxosoma cerebralis Hofer, 1903 — myxosporean spores from fish cartilage and actinosporean triactinomyxon spores from aquatic tubificids — were investigated. When the direct fluorescent antibody technique was used, anti‐triactinomyxon and anti‐M. cerebralis rabbit sera conjugated with fluorescein isothiocyanate cross‐reacted with the respective heterologous life stage. Both stages showed similar locations of specific fluorescence with conjugates of either homologous or heterologous serum. Thus, serology supports the relatedness of the myxosporean M. cerebralis and the actinosporean triactinomyxon stages.
An experimental study into the possible protection of fry from Ichthyophthirius multifiliis (Fouquet) infections during mouthbrooding of Oreochromis mossambicus (Peters)
Authors: SUBASINGHE R. P. , SOMMERVILLE C.
Published: April 2006

Abstract. The tilapine fish species belonging to the genus Oreochromis brood developing eggs and early fry in their buccal cavities. Though it is obvious that mouth brooding facilitates a physical protection from environmental hazards by keeping fry in this confined environment, it is still not clear whether mouth brooding provides any other type of protection to the early fry against pathogens. Investigations were made to study the possibility of protection of early fry of O. mossambicus against infections of the ciliate parasite Ichthyophthirius multifiliis during mouth brooding. Adult females were effectively immunized against I. multifiliis. Brooding immune females were then challenged with controlled infections of I. multifiliis tomites and the survival of the fry compared to those of challenged non‐immune brooding females. The study demonstrated that there was some protection from the infection conferred to fry during mouthbrooding.
A guideline for the preparation of species descriptions in Myxosporea
Authors: LOM J. , ARTHUR J. R.
Published: April 2006

Abstract. Guidelines for the preparation of a species description of myxosporean species are proposed. The establishment of a new myxosporean species has to be based on the morphology of both spores and vegetative stages as observed in a fresh state. All important diagnostic features are listed and diagrams for size measurements are presented.
A systemic protozoal disease of cultured salmonids
Authors: NASH G. , SOUTHGATE P. , RICHARDS R. H. , SOCHON E.
Published: April 2006

Abstract. Sporadic cases of a systemic protozoal infection with cells resembling Dermocystidium sp. are described from cultured rainbow trout, Salmo gairdneri Richardson, from France and brown trout, Salmo trutta L., and Atlantic salmon, Salmo salar L., from Ireland. Classical proliferative kidney disease was additionally found in the rainbow trout and PKX‐like cells were also seen in the brown trout and salmon.
Immunodiagnosis of Bonamia ostreae (Ascetospora) infection of Ostrea edulis L. and subcellular identification of epitopes by monoclonal antibodies
Authors: BOULO V. , MIALHE E. , ROGIER H. , PAOLUCCI F. , GRIZEL H.
Published: April 2006

Abstract. Monoclonal antibodies specific to Bonamia ostreae (Ascetospora), the intrahaemocytic parasite of the flat oyster, Ostrea edulis L., were used in an indirect fluorescent antibody assay, firstly to define the subcellular location of their epitopes and, secondly, as a means of diagnosis of the disease.
Evaluation of four methods to establish asymptomatic carriers of Aeromonas salmonicida in juvenile spring chinook salmon, Oncorhynchus tshawytscha (Walbaum)
Authors: MARKWARDT N. M. , KLONTZ G. W.
Published: April 2006

Abstract. This study evaluated four methods to establish asymptomatic carriers of Aeromonas salmonicida. Exposure of chinook salmon, Oncorhynchus tshawytscha (Walbaum), to A. salmonicida by gastric intubation resulted in a carrier prevalence of 65%. This prevalence was significantly higher than prevalences of 40, 20 and 10% after exposure respectively to broth culture bath, ingestion of broth coated feed, and exposure to intraperitoneally infected fish.
A method to eliminate the asymptomatic carrier state of Aeromonas salmonicida in salmonids
Authors: MARKWARDT N. M. , KLONTZ G. W.
Published: April 2006

Abstract. The rate of assimilation in chinook salmon of an aryl‐fluoroquinolone antibacterial from the environment as a function of time and of added chemicals (surfactants and hyperosmotic saline) was measured. A 0·01% Tween 80 antibacterial solution provided the highest serum levels of the aryl‐fluoroquinolone. This surfactant and four levels of antibacterial were used to evaluate the efficacy for elimination of the Aeromonas salmonicida carrier state in juvenile spring chinook salmon. All treatments, excepting the control, completely eliminated the asymptomatic carrier state within 48h post‐treatment. The carrier populations were monitored for 10 days and no reinfection was detected.
Morphological and biochemical differences among isolates of Yersinia ruckeri obtained from wide geographical areas
Authors: DAVIES R. L. , FRERICHS G. N.
Published: April 2006

Abstract. The morphological and biochemical characteristics of 147 strains of Yersinia ruckeri obtained from Australia, South Africa, North America and Europe were compared. The majority of strains could be divided into coccobacillary organisms or medium sized rods, but this morphological diversity was not correlated with any particular biochemical characteristic. Overall, 18% of strains were non‐motile but this was geographically biased in that 23 out of 26 non‐motile strains were isolated in the UK. Gelatin and casein hydrolysis, acetoin production, sorbitol fermentation and Tween hydrolysis were the most variable biochemical reactions. Tween hydrolysis reactions differed from the other variable characteristics in that, with the exception of a single motile reference strain, all Tween hydrolysis negative strains were non‐motile and vice versa. It is suggested that non‐motile, Tween hydrolysis negative strains be recognised as Y. ruckeri biotype 2.
The experimental histopathology of Lernaea polymorpha Yu, 1938 infection in naive Aristichthys nobilis (Richardson) and a comparison with the lesion in naturally infected clinically resistant fish
Authors: SHARIFF M. , ROBERTS R. J.
Published: April 2006

Abstract. Bighead carp, Aristichthys nobilis (Richardson), fingerlings which had not been previously exposed to nauplii of Lernaea polymorpha were infected and sacrificed at various time intervals up to 21 days. Clinical observations showed that punctate haemorrhages developed following skin penetration at 13 days post‐exposure. The adult female parasite was observed embedded in the skin and histopathology showed that the parasite penetrated the host tissue at an angle, sliding between the overlapping scales. It caused extensive tissue disruption, necrosis and haemorrhage along its path of entry, which was followed by an acute inflammatory response succeeded by a highly vascular chronic granulomatous fibrosis, whereby collagen fibres encapsulated the horns of the parasite. This contrasted with the predominantly haemorrhagic ulcerative lesions examined on immune fish subjected to natural infection, which were extensive but rarely accompanied by penetration through the dermis. There was a very extensive infiltrate of eosinophilic granular cells, club cells and lymphocytes within the spongiotic epidermis and the extensive haemorrhage was largely subepidermal.
Evidence that superficial branchial colonies on the gills of Salmo salar L. are not Aeromonas salmonicida
Authors: TURNBULL J. F. , RICHARDS R. H. , TATNER M. F.
Published: April 2006

Abstract. The indirect immunoperoxidase technique (IPT) was used to examine specific superficial colonies of organisms observed on the gills of salmonids. The evidence obtained suggested that the superficial colonies were not a form of Aeromonas salmonicida, the causative agent of furunculosis. Application of the IPT to bacterial smears and previously stained histological sections from a case of furunculosis, confirmed the sensitivity of the technique and suggested the presence of common antigens between A. salmonicida and members of the Vibrionaceae, Pseudomonaceae and Enterobacteriaceae.
Studies on cultured and gill‐attached Paramoeba sp. (Gymnamoebae: Paramoebidae) and the cytopathology of paramoebic gill disease in Atlantic salmon, Salmo salar L., from Tasmania
Authors: ROUBAL F. R. , LESTER R. J. G. , FOSTER C. K.
Published: April 2006

Abstract. The normally free‐living amoeba Paramoeba sp. is associated with epithelial hyperplasia on the gills of Atlantic salmon, Salmo salar L., in Tasmania. Gill‐attached paramoebae were significantly larger than cultured ones. Unlike cultured paramoebae, gill‐attached ones had small electron‐dense, cytoplasmic deposits and small surface projections at the host‐parasite interface. Examination of sequential samples of Tasmanian salmon gills from spring to summer indicated that pathological changes in the gill filaments were associated only with the presence of Paramoeba; the parasite was also associated with necrosis of surface epithelial cells, and cytoplasmic processes passed into and between surface cells of hyperplastic gill epithelium. The evidence points to the paramoebae as primary opportunistic pathogens causing mechanical and possibly chemical damage. Based on size and ultrastructure, the Paramoeba sp. most closely resembles P. pemaquidensis Page.
The specific detection of infectious pancreatic necrosis virus in infected cells and fish by the immuno dot blot method
Authors: HSU YA‐LI , CHIANG SHU‐YUAN , LIN SHOU‐TZU , WU JEN‐LEIH
Published: April 2006

Abstract. The immuno dot blot technique is a rapid, sensitive and quantitative method for the diagnosis of infectious pancreatic necrosis virus (ipnv) in both infected tissue culture lysates and tissue homogenates of fish. Uninfected tissue culture lysates and fish homogenates do not react in the peroxidase dot blot system after appropriate treatment. The immuno dot blot method takes 4h to complete, and the dot blot membrane can be stored in the dark for a long period. The viral proteins in the infected tissue culture cells could be detected at 3h post‐infection if an initial high MOI was used. The minimum dose of ipnv‐ab strain which could be detected using homologous serum was 2·5 ng purified ipnv protein/dot. The smallest infectious dose of VR‐299, SP, AB, EVE and CY‐1 ipnv which could be detected by the immuno dot blot system was 104 to 105 TCID50. When one μg of purified ipnv was used, a 1·6 × 104 dilution of rabbit anti‐AB antisera could be detected.
Developmental stages of kuruma shrimp, Penaeus japonicus Bate, susceptible to baculoviral mid‐gut gland necrosis (BMN) virus
Authors: MOMOYAMA K. , SANO T.
Published: April 2006

Abstract. The stages of kuruma shrimp susceptible to BMNV were determined by water‐borne infection at the fertilized egg, nauplius, zoea, mysis, and 2‐day (P‐2), 4‐day (P‐4), 6‐day (P‐6), 8‐day (P‐8) and 10‐day‐old (P‐10) post‐larval stages. Susceptibility to infection tended to decrease with advancing stages of development from zoea to P‐10. The stages from zoea to P‐4 were very susceptible, with much higher mortality and lower growth rates in virus inoculated animals compared to controls. P‐6 shrimp were also highly susceptible with all inoculated animals becoming infected with the virus. However, this group grew only slightly less well than controls and no mortality was observed. P‐8 and P‐10 post‐larvae were refractory to the disease showing no mortality and no loss of growth, even though some were slightly infected with the virus. Fertilized eggs and nauplii did not become infected with the virus using water‐borne inoculation.
Brain myxoboliasis of bullhead, Cottus gobio L., due to Myxobolus jiroveci sp. nov.: light and electron microscope observations*
Authors: LOM J. , FEIST S. W. , DYKOVÁ I. , KEPR T.
Published: April 2006

Abstract A new myxosporean, Myxobolus jiroveci sp. nov. has been found to infect the brain of bullhead, Cottus gobio L., in several localities in Czechoslovakia and England. Trophozoites, up to about 200 μm in size, were encountered in various regions of the brain where they occupied the space within the distended myelin sheath of the axons. Trophozoites provoke local compression and atrophy of the neighbouring nervous tissue. Host reaction — mostly glial cell proliferation, less often perivascular lymphocytic infiltration — can be associated with heavy infections. The sporoplasmosomes, spherical, double membrane‐bound dense bodies in the sporoplasm of mature spores, are described and compared with similar bodies of other myxosporeans and with the haplosporosomes found in representatives of the phylum Haplosporea.
Light and electron microscopic studies on Goussia zarnowskii (Jastrzębski, 1982): an intestinal coccidium parasitizing the three‐spined stickleback, Gasterosteus aculeatus (L.)
Authors: JASTRZĘBSKI M. , KOMOROWSKI Z.
Published: April 2006

Abstract. The foregut and midgut of sticklebacks, Gasterosteus aculeatus (L.), naturally infected with Goussia zarnowskii (Jastrzębski, 1982) was studied by light and electron microscopy. Trophozoites, meronts, gamonts and young oocysts developed in the intestinal epithelial cells within a parasitophorous vacuole located in an ectoplasmal position and covered by host cell plasmalemma towards the intestinal lumen. A persistent conoid, together with two polar and preconoidal rings, was present in trophozoites, young meronts and also in young macrogamonts. All developmental forms of the parasite, excluding microgamonts, were surrounded by a trimembranous pellicle consisting of an external continuous unit membrane and double‐membranous system of flattened vesicles. The micro‐gamont pellicle was reduced to a single surrounding membrane during the development of the microgamont. The manner of merogony remains unknown. The oocyst wall consisted of a double membrane of host cell origin and at least three additional membranes derived from the endoplasmic reticulum of the zygote. Material from inclusions of double electron‐density, that had occurred formerly at the periphery of the macrogamont cytoplasm, was disposed outside of the pellicle between the newly‐created oocyst wall membranes. The function of this deposit and way it passes across the pellicle membranes remains unknown. The oocyst is surrounded by the membranes of the parasitophorous vacuole and the host cell plasmalemma detached from the surface of the intestinal epithelium facing the intestinal lumen.
Distribution of X‐cell disease in common dab, Limanda limanda L., in the North Sea, and ultrastructural observations of previously undescribed developmental stages
Authors: DIAMANT A. , MCVICAR A. H.
Published: April 2006

Abstract. The distribution and prevalence of common dab, Limanda limanda L., affected with X‐cell lesions was investigated at various localities around the British Isles. Extreme variability in the prevalence of affected gills was recorded in the Moray Firth (NE Scotland), where samples obtained from hauls taken in close proximity ranged from nil to 60% of the collected dab. The condition was not detected in dab from the Irish Sea, and was found only sporadically in samples in the southern North Sea and the northwest coast of Scotland, Areas of high prevalence are typically coastal or relatively shallow habitats. The patchy distribution of the disease throughout dab populations suggests that an infectious agent may be involved in its aetiology. A method is described for rapid, accurate screening of fish samples for X‐cell disease, which utilizes the autofluorescence of the X‐cell. Ultrastructural studies of lesions from external and internal organs in dab disclosed some previously undescribed features of X‐cells. Stages of the X‐cell development which occurred in‘nests', and possibly preceded the commonly found X‐cells, were found in gill lesions. Electron dense inclusions found in X‐cells in the spleen and kidney were rod‐ or dumbbell‐shaped structures and possibly represented secretory granules.
Host‐parasite interface of Neoechinorhynchus rutili (Eoacanthocephala) in naturally infected salmonids*
Authors: TARASCHEWSKI H.
Published: April 2006

Abstract. The fine structure of the presomal tegument of Neoechinorhynchus rutili is described from worms attached to the intestinal wall of salmonid fishes. The host's cellular reaction at the worms’ point of attachment is described from the same hosts. The acanthocephalans’ presomal surface coat had a liquid lipid appearance. It seemed to be fed by droplets of lipid from necrotic host cells, by the contents of the granules of the hosts' coarsely granulated granulocytes and by excretions of the parasite. The crypts of the worms’ presomal outer limiting membrane were unbranched while those of the metasoma branched up in the striped layer. The striped layer of the proboscis hooks was more sclerotized than that of the surrounding (presomal) tegument. Inward from the hooks’ striped layer the crypts formed a mesh. The contents of the crypts were usually continuous with the presomal surface coat. The host's intestinal tissue in the region of the worms’ proboscides was heavily inflamed, especially around the hooks, where numerous granulocytes accumulated and degranulated. The acanthocephalans did not seem to be adversely affected by the inflammation and survived for at least 6 months in fish kept in the laboratory. The inflammatory tissue around the proboscides of worms exceeding a length of about 5 mm was enriched with fibroblasts and collagen fibres forming a capsule. Generally, the worms showed a shallow attachment. They were never found in extra‐intestinal positions.
Prevalence and development of intraleucocytic haemogregarines from Northwest and Northeast Atlantic mackerel, Scomber scombrus L.
Authors: MACLEAN S. A. , DAVIES A. J.
Published: April 2006

Abstract. Scomber scombrus on both sides of the North Atlantic were infected with similar intraleucocytic haemogregarines. Detection of parasites in blood smears alone was found to be an unreliable indicator of prevalence. In the Northwest Atlantic, prevalence of blood infections varied annually and seasonally, with an average of 18.4%, whereas tissue imprints showed up to 98.3% prevalence. Northeast Atlantic fish had a 4.0% prevalence in blood smears and 100% in spleen imprints. Age 1 mackerel were the principal hosts of haemogregarines in the Northwest Atlantic. Scanty infections of single and paired parasites were observed primarily in lymphocytes and neutrophils of peripheral blood and tissue imprints. Also present in the blood and tissues of Northwest Atlantic mackerel were intracellular schizonts with up to 20 merozoites, and fish from the same region showed haemogregarines within histological lesions in kidney and spleen. Ultrastructural studies on Northeast Atlantic mackerel indicated the parasite is apicomplexan and morphologically dissimilar to Haematractidium scombri. Its relationship with Goussia clupearum was not determined.
Gill organ culture of rainbow trout, Salmo gairdneri Richardson: an experimental model for the study of pathogenicity of Mycoplasma mobile 163 K
Authors: STADTLÄNDER C. , KIRCHHOFF H.
Published: April 2006

Abstract. A method has been developed to maintain gills from rainbow trout, Salmo gairdneri Richardson, in vitro. The gill organ cultures were used to examine the cytotoxic capacities of Mycoplasma mobile 163 K, isolated from the gills of a tench, Tinea tinea L. Histological investigations using light and electron microscopy showed that M. mobile causes heavy damage to the gill epithelium characterized by cytoplasmic vacuolization, peripheral orientation of the condensed nuclear chromatin, separation of the epithelial cells from each other and from the basal membrane, desquamation of the epithelial layer, shrinkage of the cytoplasmic net structure, and a swollen and bleb–like appearance of the apical area of the secondary lamella. The gill organ culture appears to be a suitable model to investigate the cell injuring capacity of M. mobile and may also be applicable to the study of the pathogenic properties of other microorganisms or viruses of fish.
Fry age and size effects on immersion immunization of brook trout, Salvelinus fontinalis Mitchell, against infectious pancreatic necrosis virus
Authors: SCOTLAND L. M. , DOBOS P. , STEVENSON R. M. W.
Published: April 2006

Abstract. Brook trout, Salvelinus fontinalis Mitchell, fry were divided into eight age groups of 1–8 weeks post‐hatch (wph) and immunized by a single direct immersion in formalin‐inactivated infectious pancreatic necrosis virus (ipnv). After a direct‐immersion ipnv challenge given 4 weeks later, only fry immunized at 2, 3 and 6wph showed protection. The relative per cent survival 60 days after ipnv challenge was highest in 2 and 3 wph fry (45–50%) and decreased as fish increased in age or size. The same response was obtained one year later when four age groups of fry, from 1 to 4wph, were immunized with a different serotype and dose of ipnv. The 2 and 3 wph fry had mean weights between 49 and 60mg at immunization. Killed vaccines administered by immersion have not previously been reported as inducing protection in salmonid fry of such low weights. Analysis of the growth of the fry suggests that protection against IPNV requires immunization in the eleutheroembryo phase, during the time of slow weight gain. This appears to be in direct contrast to the stage of ontogeny and weight growth rate required for successful immunization against the bacterial pathogen Vibrio anguillarum. Although immunization with two ipnv serotypes reduced mortalities from challenges with these same virus isolates, it did not prevent ipnv infection of fry in any age group.
Isometric twitch tension of lateral muscle in carp, Cyprinus carpio L., with sekoke disease
Authors: KAKUTA I. , NAMBA K.
Published: April 2006

Abstract. Changes in blood properties and the chemical components, histology and isometric twitch tension of lateral muscle were studied in carp, Cyprinus carpio L., showing clinical signs of sekoke disease induced by a diet containing oxidized oil. When compared to normal fish, sekoke fish were found to have significantly lower mean blood pH, haematocrit, haemoglobin concentration and muscle water content. However, plasma lactate, lipoperoxide and total lipid concentrations were significantly higher in sekoke fish. It was found that in sekoke fish the maximum tension and the number of isometric twitches leading to complete fatigue of lateral muscle were greatly reduced. Histological studies confirmed that these reductions were related to the degree of structural damage within this tissue.
Sphaerospora testicularis sp. nov. (Myxosporea: Sphaerosporidae) in wild and cultured sea bass, Dicentrarchus labrax (L.), from the Spanish Mediterranean area
Authors: SITJA‐BOBADILLA A. , ALVAREZ‐PELLITERO P.
Published: April 2006

Abstract. A new myxosporean, Sphaerospora testicularis sp. nov., was found in fresh smears from the organs of wild and cultured sea bass, Dicentrarchus labrax (L.), and seminal fluid from spermiating cultured males. It is distinguished from all previously reported Sphaerospora spp, by the shape and dimensions of the mature spore, its location and the host and its geographical distribution. Only males were parasitized; 2.5% of the wild fish and 6‐25% of the cultured fish were infected. In spermiating cultured males, the prevalence of infection increased progressively from 6‐9 to 75% during the study period. The parasite causes destruction of the tubular tissue of testes and a reduction or loss of spermatozoa.
The survival of Aeromonas salmonicida subsp. salmonicida in sea water
Authors: ROSE A. S. , ELLIS A. E. , MUNRO A. L. S.
Published: April 2006

Abstract. The survival of Aeromonas salmonicida subsp. salmonicida was investigated in sea water under a variety of conditions. Survival in different types of microcosms (glass or dialysis bags); of bacteria grown under both in vivo and in vitro (broth culture) conditions; and in sterile and non‐sterile sea water were compared. In all cases, survival was found to be of short duration (<10 days) and did not conflict with the previously stated obligate nature of the pathogen. The spread of furunculosis may depend less on its ability to survive in the environment than on its rate of shedding from infected fish and prevailing hydrographic conditions. Survival was extended and growth occurred in sterile sea water to which nutrients (tryptone soya broth) had been added. However, sea water obtained from beneath a commercial salmon cage, which would have been expected to be nutrient rich, did not prolong the survival of the pathogen. In vivo infectivity studies provided no evidence for the existence of unculturable but infective forms of A. salmonicida subsp. salmonicida which, therefore, validates the use of colony‐forming units as a measure of survival.
Nutritional requirements for extracellular accumulation of toxin produced by a pathogenic Vibrio sp.
Authors: BROWN C.
Published: April 2006

Abstract. A Vibrio species isolated from hatchery‐reared, diseased oyster larvae, Crassostrea virginica Gmelin, was shown to produce a teratogenic metabolite when grown in a complex, undefined medium. Nutritional studies determined that the pathogen required several inorganic salts, glucose and asparagine for growth. Bioassays demonstrated that toxin did not accumulate in this chemically‐defined medium. However, toxin accumulation did occur when the medium was supplemented with hypoxanthine and either glutamic acid, histidine or thiosulphate.
Adherence, haemagglutination and cell surface characteristics of motile aeromonads virulent for fish
Authors: DEL CORRAL F. , SHOTTS E. B. , BROWN J.
Published: April 2006

Abstract. Motile Aeromonas spp. virulent for fish were studied with regard to their adhesion profile. Electron microscopy demonstrated the presence of fimbriae (pili) on Aeromonas cells regardless of virulence potential. The results show no significant correlations between ability to haemagglutinate, yeast cell co‐agglutination and virulence. All strains expressed mannose‐sensitive haemagglutinin activity against guinea pig erythrocytes. Using four types of red blood cells no characteristic haemagglutinin pattern related to virulence could be discerned. Expression of surface haemagglutin(s) on Aeromonas hydrophila appears to be medium dependent; strains grown in liquid media demonstrated enhanced haemagglutination activity. Both virulent and avirulent strains had in vitro epithelial cell adhesive capabilities. Cell surface characteristics measured by agglutination in acriflavine and stability after boiling indicated that most virulent strains agglutinated in the presence of acriflavine, but not all sedimented after boiling. The ability of 10 selected strains of A hydrophila to grow in normal pooled catfish serum was determined. Only 17% of the virulence variations can be explained by their sensitivity to serum.
A large tumour from the gray snapper, Lutjanus griseus (L.)
Authors: SMITH A. C. , WANG T.‐ Y.
Published: April 2006

Abstract. Using a panel of special stains employed in human histopathology and immunohistology, the authors diagnosed a tumour from the common gray snapper, Lutjanus griseus (L.), as a myoma, Only a few such tumours have been previously reported from fishes. Gray snapper are readily available and may provide a model for basic studies on this, as well as other, types of tumour.
In vitro activities of oxolonic acid, ciprofloxacin and norfloxacin against Aeromonas salmonicida
Authors: LEWIN C. S. , HASTINGS T. S.
Published: April 2006

Abstract. Oxolinic acid and two new fluoroquinolones, ciprofloxacin and norfloxacin, were evaluated for in vitro antibacterial activity against Aeromonas salmonicida. Although oxolinic acid was as active as ciprofloxacin in terms of minimum inhibitory concentration (MIC), fluoroquinolones were significantly more active in terms of their ability to kill both oxolinic acid sensitive and resistant strains of A. salmonicida. Furthermore, the fluorinated drugs were active against non‐dividing A. salmonicida. It would appear worthwhile to carry out further investigations with fluoroquinolones as they may be more effective in treating A. salmonicida infections than the current regime of oxolinic acid.
A 6‐year study of Thelohania contejeani parasitism of the noble crayfish, Astacus astacus L., in Lake Steinsfjorden, S. E. Norway
Authors: SKURDAL J. , QVENILD T. , TAUGBØL T. , FJELD E.
Published: April 2006

Abstract. During 1981‐1986, the mean prevalence of Thelohania contejeani parasitism of the noble crayfish, Astacus astacus L., in Lake Steinsfjorden, S. E. Norway, was 0.29%. The crayfish population is heavily exploited. Thelohania contejeani infection levels increased significantly during the fishing season, and variations between years were more pronounced in catches after the fishing season (0.38‐2.11%) compared to catches before the fishing season (0.05‐0‐19%). Sixty‐eight per cent of the variation between years could be explained from variations in trap effort. Scuba‐diving yielded significantly higher T. contejeani infection levels than simultaneous trapping with baited traps. Thus, in years with heavy exploitation, a larger fraction of non‐infected crayfish are removed from the population as these are more susceptible to capture. The findings do not support the hypothesis that density and cannibalism influence T. contejeani infection.
Ultrastructural studies on the endogenous stages of Eimeria variabilis (Thélohan, 1893) Reichenow, 1921, from Coitus (Taurulus) bubalis Euphrasen (Teleostei: Cottidae)
Authors: DAVIES A. J.
Published: April 2006

Abstract. Ultrastructural studies on the endogenous stages of Eimeria variabilis from the marine fish Cottus bubalis showed macrogamonts that resembled those of other fish coccidia except for small and large, probably protcinaceous, intracytoplasmic dense bodies. Similar dense bodies occurred in oocysts, but were not identified as wall forming bodies since many extruded from the contracted oocyst contents during sporulation. The thin, two‐layered oocyst wall (20 nm across) may have derived from smooth endoplasmic reticulum and the plasma membrane of the late macrogamont. At sporogony, the oocyst wall frequently peeled inwards in scroll‐like formations to leave a membrane 3‐nm thick, possibly of host origin. Sporogony produced four uninucleate sporoblasts that developed with some asynchrony within a single oocyst. Sporoblasts were limited by a single membrane initially, and additions to this membrane, apparently from dense material and filaments outside the sporoblast, built up the sporocyst wall. An area of Stieda‐like body formation was identified on the sporocyst wall and no other exit for sporozoites was seen. Full description of sporozoites, microgamonts and meronts awaits further study but similarities with those of other coccidia were noted.
Lernea cyprinaceaL. (Copepoda: Caligidea) inHelostoma temminckiCuvier & Valenciennes: the dynamics of resistance in recovered and naive fish
Authors: WOO P. T. K. , SHARIFF M.
Published: April 2006

Abstract.All recovered and naiveHelostoma temminckilost their infections 30 days after homologous challenge withLernaea cyprinacea.It is suggested that there is acquired protective immunity in recovered fish. No parasites were detected in five out of 20 recovered fish when the infective challenge dose was low; all naive fish (20) in the same tank were infected. In another experiment, all nine recovered fish were infected when the challenge infective dose was high. Recovered fish lost their infections (i.e. number of fish with no parasites and the number of parasites rejected) much faster than naive fish and this was very evident in the first 2 weeks after challenge. Parasites on recovered fish lost more egg sacs than naive fish during the same period. Eggs from parasites on recovered fish either did not hatch or were not infective or only caused a very low transitory infection in naive fish. It is suggested that, if no naive fish are introduced into a closed system for a period (and this has to be determined under field conditions) after an outbreak, then there will be no infective larvae in the water and the system will now be safe for restocking. This novel approach to control of the parasiteL. cyprinaceaand the spread of this disease will have to be carefully tested under field conditions.
Myoliquefaction post‐mortem (‘milky flesh’) due to Kudoa thyrsites (Gilchrist) (Myxosporea: Multivalvulida) in mahi mahi, Coryphaena hippurus L.
Authors: LANGDON J. S.
Published: April 2006

Abstract. Myoliquefaction occurred post‐mortem in wild and cultured mahi mahi, Coryphaena hippurus L., stored on ice, and the flesh disintegrated upon cooking. The condition was associated with multifocal infection of muscle with Kudoa thyrsites (Gilchrist). Histiolysis is presumably due to enzymes excreted by the parasite, including collagenases, as the collagen fibres of the intermyotomal connective tissues were ruptured and hypochromatic. Myofibre changes were limited to hyaline degeneration and loss of myofibrillar detail. Kudoa thyrsites occurs commonly in Australian populations of the type host species, Thyrsites atun (Euphrasen), which represent a partly sympatric reservoir of infection for C. hippurus. The successful culture of C. hippurus may require selection of disease‐free sites or use of filtered water supplies.
Secular trends in socio‐economic status and the implications for preterm birth
Authors: Thompson John M. D. , Irgens Lorentz M. , Rasmussen Svein , Daltveit Anne Kjersti
Published: April 2006

The rate of preterm birth in the developed world has been shown to be increasing, in part attributable to obstetric intervention. It has been suggested that this may be a differential increase between socio‐economic groups. We aimed to assess whether the preterm rate in Norway is different in socio‐economic groups defined by maternal education, and to determine the extent to which a difference is attributable to a socio‐economic differential in obstetrical intervention, in terms of caesarean section or induction of labour. We used data from the Medical Birth Registry of Norway from 1980 to 1998 with preterm rate as the outcome and maternal educational level, marital status and obstetric intervention as exposure variables. In multivariable analyses, adjustment was made for maternal age, year of birth and birth order, and secular trends were assessed according to year of birth.

The preterm birth rate was highest in the lowest socio‐economic group. An increase of 25.2% in the preterm rate was seen over the observation period. No apparent differential was seen in the increase of the crude preterm rates between socio‐economic groups, although in multivariable analyses there was a significant interaction between socio‐economic group and time, implying a stronger effect of low education towards the end of the observation period attributable to demographic change. In conclusion, the preterm birth rate increased over time, but was mainly due to an increase in obstetric interventions. No closing of the gap between socio‐economic groups was observed.
Is conception delay a risk factor for reduced gestation or birthweight?
Authors: Cooney Maureen A. , Buck Louis Germaine M. , Sun Wenyu , Rice Madeline M. , Klebanoff Mark A.
Published: April 2006

Previous studies have suggested an association between delays in conception and adverse perinatal outcomes, specifically, low birthweight and preterm birth. We investigated the relationship between conception delay (defined as >6 months to become pregnant) and three perinatal outcomes: low birthweight (LBW; <2500 g), preterm birth (PTB; <37 weeks), and small‐for‐gestational‐age (SGA; <10th percentile weight for given gestational age) using data from the Collaborative Perinatal Project. The study cohort was limited to pregnancies with a known time‐to‐pregnancy (n = 8465; 15%). Generalised estimating equations were used to estimate odds ratios (OR) and 95% confidence intervals [CI] for risk of adverse perinatal outcomes accounting for the clustering of pregnancy outcomes for women with more than one pregnancy. After adjusting for confounders, all ORs were close to the null (LBW, OR = 1.01; 95% CI = 0.86, 1.20), (PTB, OR = 1.10; 95% CI = 0.95, 1.27), (SGA, OR = 1.06; 95% CI = 0.91, 1.25). Thus, we found no evidence to support an adverse relationship between conception delay and decrements in gestation or birthweight among this select sample of fertile women, even after varying the cut‐point for defining conception delay.
The Belgrade childhood diabetes study – comparison of children with Type 1 diabetes with their siblings
Authors: Vlajinac Hristina , Šipetić Sandra , Marinković Jelena , Bjekić Milan , Kocev Nikola , Sajić Silvija
Published: April 2006

A case–control study was conducted in Belgrade (about 320 000 inhabitants 0–16 years old) during the period 1994–97, comprising 68 diabetic children (cases) and 68 controls chosen from the siblings of the cases.

Analysis using multivariable logistic regression analysis indicated the following independent risk factors for Type 1 diabetes: higher birth order, infections during the 6 months preceding the onset of the disease and stressful events. Out of individual stressful and psychological factors, ‘other’ stressful events (severe accident or hospitalisation or death of a close friend, conflict with a teacher, death of a pet, failure in competition, quarrel between parents, punishment, physical attack, war in republics of former Yugoslavia and near drowning in the pool) and learning problems were independent risk factor for Type 1 diabetes. The results obtained in this study of siblings supports the hypothesis that environmental factors play a role in the development of Type 1 diabetes.
Statistical modelling of the seasonality of preterm delivery and intrauterine growth restriction in rural Gambia
Authors: Fulford Anthony J. C. , Rayco‐Solon Pura , Prentice Andrew M.
Published: April 2006

We have developed a methodology for comparing the seasonal influences on two outcomes, when those influences may act cumulatively or instantaneously. We have used this to compare the seasonal pattern of intrauterine growth retardation (IUGR, as reflected by weight‐for‐gestational‐age) and preterm delivery (as assessed by Dubowitz scoring) among 1718 infants born in rural Gambia. Both outcomes were analysed as binary variables: small‐for‐gestational‐age (SGA, <10th centile of reference standard) and preterm (<37 weeks) respectively. Percentages of preterm and SGA babies show divergent seasonal patterns that might indicate separate aetiologies. However, seasonal effects influencing intrauterine growth are likely to be cumulative over the last few months of pregnancy. By modelling seasonality with truncated Fourier series we were able to deconvolve the underlying seasonal influences on fetal growth from the pattern for SGA. This enabled us to use seemingly unrelated biprobit regression to compare the underlying seasonal pattern of intrauterine growth with that governing the incidence of preterm delivery.

We conclude that, if the seasonal factors affecting intrauterine growth operate over more than the last 2 months of pregnancy, then the seasonal patterns of the factors causing IUGR and preterm delivery are indistinguishable if the factors are assumed to trigger preterm delivery immediately, but differ if preterm delivery is assumed to be programmed by factors acting at conception.
Maternal miscarriage history and risk of anencephaly
Authors: Blanco‐Muñoz Julia , Lacasaña Marina , Borja‐Aburto Victor Hugo
Published: April 2006

Women with a history of reproductive loss may be at an increased risk of having an unfavourable outcome in subsequent pregnancies. Using data from a matched case–control study based on the record of the Epidemiological Surveillance System of Neural Tube Defects, we evaluated the association between history of maternal reproductive loss and the risk of anencephaly in three Mexican states. Mothers of 157 cases of anencephaly and 151 controls born during the period March 2000 to February 2001, were interviewed about their reproductive history and other additional factors, including socio‐economic characteristics, prenatal care, use of tobacco and alcohol, presence of chronic diseases, acute illnesses and fever during the periconceptional period, and consumption of multivitamins and medicines during this period; mothers who reported no prior pregnancies were excluded from the analysis; 58 matched case–control pairs were used for the analysis.

After adjusting for potential confounders, women with a history of miscarriage in previous pregnancies had 4.58 times more risk of having a child with anencephaly, than those who did not have this history; OR = 4.58, [95% CI 1.22, 17.23]. Our results suggest that a history of previous miscarriages is a risk indicator for anencephaly in future gestations. This does not necessarily mean that the miscarriage itself is the cause, but that common mechanisms could be involved in the aetiology of both events. Thus, women who have had histories of reproductive losses, especially miscarriages, should be a priority group for the primary and secondary prevention of neural tube defects.