bluuebunny/crossref_metadata_2025 huggingface dataset:
Histopathological changes in the liver and brain of fish exposed to endosulfan insecticide during tsetse fly control operations in Botswana
Authors: MATTHIESSEN P. , ROBERTS R. J.
Published: April 2006

Abstract. During tsetse fly control operations, fish in the Okavango Delta region of Botswana are exposed to ultra–low–volume doses (6–12 g/ha) of endosulfan, an insecticide recognized to be highly toxic to fish. Approximately 1 % of the fish population can be killed by a spray, and the physiology and behaviour of survivors is temporarily disturbed. Simultaneously with the onset of the spraying season (July), the livers and brains of several species [including Clarias gariepinus (Burchell) and Tilapia rendalli (Boul.)] developed pathological lesions which often persisted until the season ended (October). Initially, hepatic lesions in C. gariepinus were characterized by generalized toxic necrosis, focal necrosis, and subcapsular oedema which gradually lessened in intensity and disappeared before the spraying season ended. Melano‐macrophage centres and perivascular haemopoietic elements were lost from poisoned livers and were not replaced until at least 6 months later. In T. rendalli brain, pesticide–related changes included encephalitis, meningitis and oedema, with an associated inflammatory infiltrate of eosinophilic granule cells. Most brain damage disappeared during the month after the spraying season, although glial scarring was occasionally observed in fish sampled later. The possible connection of these abnormalities with observed behavioural changes is discussed.
Chlamydia‐like organisms in the digestive diverticula of the bay scallop, Argopecten irradians (Lmk)
Authors: MORRISON CAROL , SHUM G.
Published: April 2006

Abstract. The morphology of a chlamydia‐like organism from the digestive diverticula of the bay scallop, Argopecten irradians (Lmk), is described. This organism was found in about 40% of bay scallops introduced to the quarantine unit at Ellerslie, Prince Edward Island, Canada and also in about 40% of the F1 and F2 generations. Procaryote infections were also found in the northern quahog, Mercenaria mercenaria (L.), the soft‐shelled clam, Mya arenaria L., and the Atlantic deepsea scallop, Placopecten magellanicus (Gmelin).
Studies on the pathology of ulcerative dermal necrosis (UDN) in Swedish salmon, Salmo salar L., and sea trout, Salmo trutta L., populations
Authors: JOHANSSON N. , SVENSSON K. M. , FRIDBERG G.
Published: April 2006

Abstract. Continuous visual observations of the signs of development of UDN in fish kept in aquaria were correlated with light microscopical, transmission and scanning electron microscopical results. The initial signs of the disease are circles of pathologically‐changed epidermis. The tight junctions of the squamous cells within these mucus‐free areas disintegrate resulting in the loss of the protective function of the zonula occludens. Subsequently, the intercellular spaces dilate and communicate with the exterior. Necrosis of the epidermal cells due to hydromineral disturbances occur simultaneously with fungal infections and marked responses of the melanophores. It is suggested that the fungal infections are triggered by metabolites of the necrotic epidermal cells. The epidermal cells are shed and the fungus determines the further course of the disease which terminates in large ulcers covered with fungal hyphae. No substantial evidence for the presence of a virus could be recorded at any stage of the disease. It is concluded that the disease is a squames and the fungus appears as an opportunist which causes the eventual death of the fish.
Histopathology of Pleuronectes platessa L. from Aber Wrac'h and Aber Benoit, Brittany, France: long‐term effects of the Amoco Cadiz crude oil spill
Authors: HAENSLY W. E. , NEFF J. M. , SHARP J. R. , MORRIS A. C. , BEDGOOD M. F. , BOEM P. D.
Published: April 2006

Abstract. Organ samples were collected from plaice, Pleuronectes platessa L., captured in the highly oiled Aber Wrac'h and Aber Benoit at five intervals during the period 1978‐1980, following the Amoco Cadiz crude oil spill. Reference plaice were obtained along the western and southern coasts of Brittany. Tissue samples were fixed, processed and stained by routine histologic procedures for qualitative and quantitative histopathological examination. The predominant lesions and conditions which characterized fish from the oiled estuaries were: fin and tail necrosis, hyperplasia and hypertrophy of gill lamellar mucous cells, gastric gland degeneration, decreased hepatocellular vacuolation (lipid), increased concentration of hepatic macrophage centres and lateral trunk muscle fibre degeneration. Dilation of Bowman's space, glomerular hypertrophy and abdominal muscle fibre degeneration were pronounced at the last sampling interval. Other types of lesions were seen at a lower frequency: hyperplasia and fusion of gill lamellar epithelium, telangiectasis of gill capillaries, hepatopancreatic degeneration and hepatic necrosis. Fish muscle and liver collected for biochemical analysis to detect the presence or absence of petroleum hydrocarbons were negative for Amoco Cadiz oil fractions. At the same time oysters, Crassostrea gigas Thunberg, collected from the oiled estuaries throughout the study period, showed high levels of Amoco Cadiz oil fractions. These data, along with the type and frequency of lesions observed, suggested that the plaice had been chronically‐exposed to petroleum hydrocarbons of Amoco Cadiz origin. Some relief from chronic pollutant exposure was indicated by a decrease in gill mucous cell concentration at the last sampling interval. An increase in abdominal muscle fibre degeneration and an increase in the frequency of dilation of Bowman's space with glomerular hypertrophy at the last sampling interval suggested a latent response to the polluting agent.
Tribrissen® and tiamulin for control of enteric redmouth disease
Authors: BOSSE MARIE P. , POST G.
Published: April 2006

Abstract. Fifteen drugs were tested for in vitro control of Yersinia ruckeri. Those drugs yielding in vitro control were subsequently tested for in vivo control of induced enteric redmouth disease in rainbow trout. Two of the drugs, Tribrissen®v and tiamulin, controlled Y. nickeri in vivo under laboratory conditions. The effective doses used in this study were 1–0 mg of Tribrissen/kg fish/day and 5–0 mg of tiamulin/kg fish/day, when the compounds were administered orally for 14 days. No toxic effects were noted at these dose levels, or from Tribrissen given at 15 times the above effective dose.
Ultrastructure of the microgamont and microgamete ofEimeria funduli, a coccidium parasitizing killifishes
Authors: HAWKINS W. E. , SOLANGI M. A. , OVERSTREET R. M.
Published: April 2006

Abstract.The ultrastructure of the microgamont and microgamete of the coccidiumEimerici funduliwas studied in hepatocytes of the killifishFundulus grandisandF. similis. During microgametogenesis, the nuclear chromatin condensed, marginated, then differentiated into a peripheral dense portion that became the nucleus of the microgamete and a central clear portion that remained in the gamont. Near each nucleus was a mitochondrion and four microtubules which were incorporated into the microgamete. In microgamonts, dense polysaccharide granules (50–60 nm diameter) were demonstrated with the periodic acid‐thiocarbohydrazide‐silver proteinate method. Flagella extended into the parasitophorous vacuole from basal bodies situated near nuclei. Microgametes budded from the surface of the microgamonts. The microgamete consisted of a nucleus, two flagella and basal bodies, a mitochondrion, a rudimentary basal body, four microlubules, a perforatorium, and a dense rod‐like structure. The elongate nucleus was narrow anteriorly and bulb‐like posteriorly. One of the flagella was attached to the body of the microgamete. A mitochondrion that was swollen anteriorly and constricted posteriorly ran alongside the nucleus. The four microtubules appeared to arise from a rudimentary basal body and were closely related to the mitochondrion. Two of them extended nearly the length of the nucleus. The rod‐like structure appeared to develop from a thickening of the limiting membrane of the microgamont. Fertilization was not directly observed, but microgametes were found in the parasitophorous vacuoles of several macrogamonts.
Histopathology of oxygen intoxication in the juvenile red abalone, Haliotis rufescens Swainson
Authors: ELSTON R.
Published: April 2006

Abstract. Juvenile abalone were exposed to supersaturated oxygen conditions (about 150–200% of saturation) in order to reproduce similar conditions encountered in intensive husbandry systems and to then study the resultant lesions. Depigmentation, lethargy and swelling of tissues were observed clinically. Histopathology showed that the cytoplasmic vacuoles of large haemocytes were enlarged. Oxygen emboli were observed throughout the muscular tissue and connective tissue but separation of fibrous neural sheath from nerve cell bodies and surrounding tissue was the predominant lesion. Chromatin of the nuclei of nerve cells became marginated. Gaseous emboli were observed at various other locations in the vascular system. At termination of the experiment all animals sampled bacteriologically showed systemic infection with Vibrio alginolyticus. The clinical signs appeared to result from mechanical interference caused by the accumulation of oxygen and from dysfunction of neural structures. The predominant histopathological changes occurred after only 3 h or less exposure time. Normal histology of the haemocytes and nerve structures is described.
Ultraviolet light control of Ichthyophthirius multifiliis Fouquet in a closed fish culture recirculation system
Authors: GRATZEK J. B. , GILBERT JEANNINE P. , LOHR AMY L. , SHOTTS E. B. , BROWN J.
Published: April 2006

Abstract. A closed fish culture recirculation system consisting of 36 20‐gallon aquaria in series with a rotating plate biofilter, a diatomaceous earth filter, and an ultraviolet (UV) light sterilizer was evaluated for the effectiveness of UV light in preventing spread of Ichthyophthirius multifiliis. Water from the aquaria, the reservoir, and a valve 29 cm beyond the UV light source was analysed bacteriologically to assess its effectiveness. The spread of I multifiliis from one aquarium to another was controlled with 91 900 μW s/cm8 of UV light. No significant differences in the bacterial counts from the water of the reservoir or the aquaria could be demonstrated when the UV light was either on or off, although a significant difference could be demonstrated between the sterilizer effluent and the reservoir and aquaria.
An experimental model for fish furunculosis caused by Aeromonas salmonicida
Authors: MCCARTHY D. H.
Published: April 2006

Abstract. Development of an experimental bath challenge method for fish furunculosis caused by Aeromonas salmonicida is described. The influence of certain important experimental variables was investigated and standardized. Possible application of the model is discussed.
Susceptibility of Chinook salmon, Oncorhynchus tshawytscha (Walbaum), and rainbow trout, Salmo gairdneri Richardson, to infection with Vibrio anguillarum following sublethal copper exposure*
Authors: BAKER R. J. , KNITTEL M. D. , FRYER J. L.
Published: April 2006

Abstract. Chinook salmon, Oncorhynchus tshawytscha (Walbaum), and rainbow trout, Salmo gairdneri Richardson, were used to determine if sublethal copper exposure would increase their susceptibility to Vibrio anguillarum infection. Fish were pretreated with copper at fractional levels of the 96 h copper LC50 before exposure to the pathogen. Mortality by vibriosis was greater among fish exposed to 9% of the copper LC50 for 96 h than unexposed fish. Peak susceptibility to vibriosis depended in part on the interaction of exposure time and copper concentration. The higher copper concentrations produced peak susceptibility to infection in shorter time periods. After the peak of susceptibility, sensitivity to infection declined to near control levels in those fish where exposure was continued. Rainbow trout stressed by copper required about 50% fewer pathogens to induce a fatal infection than non‐copper exposed fish.
Some factors affecting the potency of Yersinia ruckeri bacterins
Authors: AMEND D. F. , JOHNSON K. A. , CROY T. R. , McCARTHY D. H.
Published: April 2006

Abstract. Several factors affecting the potency of Yersinia ruckeri bacterins were evaluated by vaccinating rainbow trout, Salmo gairdneri Richardson, with various bacterins using the immersion method and determining the level of protective immunity after a virulent challenge. The potency of bacterins prepared with tryptic soya broth at room temperature was not affected by growth at pH from 6.5 to 7.7 or by a culture age from 9 to 96 h. Chloroform and formalin inactivated (0.3%) bacterins gave comparable results and no enhancement of potency occurred by prior extraction of bacterial cells with either butanol or phenol. Cell lysis, as measured by reduced optical density, occurred when cells were held at pH 9–8 for 60 to 120 min. Bacterins prepared from pH‐lysed cells resulted in a significant increase in protective immunity. Bacterins prepared at pH 7.2 for 48 h, pH‐lysed and inactivated with 0.3 % formalin could be diluted up to 1:100 without loss of efficacy when applied to rainbow trout by a single 20 s immersion. However, with bacterin diluted 1:10 loss of potency occurred after 20 consecutive immersions (100 kg of fish) in the same bacterin at a rate of 0.5 kg/1 of diluted bacterin for each immersion. Factors affecting optimum duration of immunity are discussed.
Inactivation of infectious pancreatic necrosis virus for vaccine use
Authors: DIXON P. F. , HILL B. J.
Published: April 2006

Abstract. Formalin and β‐propiolactone (BPL) were compared for efficacy in inactivating infectious pancreatic necrosis virus (IPNV) for vaccine use. Incubation with a 1:200 dilution of formalin at 20°C for four days or longer, or a 1:200 dilution of BPL at 4°C for six days or longer, completely inactivated the virus infectivity. However, whereas treatment with formalin caused only a slight reduction in anti‐genicity as titrated by in vitro tests, treatment with BPL destroyed over 50% of the antigenicity of the virus. Virus inactivated with formalin also proved highly effective at inducing high titres of neutralizing antibody in trout.
Ultrastructural study of Pisdnoodinium pillulare (Schäperclaus, 1954) Lom, 1981 with special emphasis on its attachment to the fish host
Authors: LOM J. , SCHUBERT G.
Published: April 2006

Abstract. Trophonts of Pisdnoodinium pillulare (Schäperclaus, 1954), a common ectoparasite of freshwater aquarium fish, are attached to host cells by means of a specialized structure, the attachment disc. Unlike other dinoflagellate genera parasitic on fish and invertebrates, this disc features nail‐like organelles, the rhizocysts. Head‐parts of the rhizocysts are inverted in separate compartments, rhizothecas, in the sole of the disc while their long shafts are firmly embedded in the cytoplasm of cells of the host epidermis or gill epithelium. The attachment inflicts a serious injury on the host cells which may ultimately be destroyed. Rhizocysts originate in the subnuclear cytoplasm from where they migrate into the attachment disc. There are other specialized organelles and inclusions; fibrous vesicles, membraneous bodies, striated tubular bodies and paracrystalline bodies. Pisdnoodinium has well‐developed chloroplasts. While its cytological adaptations indicate a nutritional dependence on the host, there is no evidence of ingestion of host‐derived particulate material. Pisdnoodinium may derive an essential part of its nutrition from photosynthesis.
The pathology of Myxidium giardi Cépède, 1906 infections in wild and cultured eels, Anguilla anguilla L.
Authors: COPLAND J. W.
Published: April 2006

Abstract. The histopathology of Myxidium giardi infections in wild and cultured elvers, fingerlings and adult eels is described. The lesions in the target organs of the kidney and gills were minimal. Marked granulomatous changes were evident in the spleen, peritoneal fat and, to a lesser extent, the liver and gas gland. The granulomatous reaction consisted of a mononuclear infiltration into the spore mass and proliferative fibrosis of the surrounding connective tissue, Histological evidence of an immunological response is described. The types of M. giardi cysts are described‐a primary interstitial cyst of the kidney and gill, a secondary cyst of the gills and a glomerular spore mass. Primary interstitial cysts in the kidney were observed to rupture and formed spore masses in the interstitial tissue. Evidence of vascular spread and the presence of spore emboli is presented. It is suggested that primary multiplication occurs in the primary interstitial cyst of the kidney and gills, and secondary multiplication in the secondary gill cyst and glomerular spore mass from which mature spores are released to the environment.
Histopathology of four spontaneous neoplasms in three species of salmonid fishes*
Authors: MEYERS T. R. , HENDRICKS J. D.
Published: April 2006

Abstract. Gross and histological descriptions of four different spontaneous neoplasms in three species of salmonid fishes are provided: thymic lymphoma and dermal fibrosarcoma, respectively, in two artificially reared sockeye salmon, Oncorhynchus nerka (Walbaum); renal papilliferous cystadenoma in a wild caught chinook salmon, O. tshawytscha (Walbaum); capillary haemangioma of the dermis in an artificially reared rainbow trout, Salmo gairdneri Richardson. The frequency of occurrence of these and related tumour types, as reported in the literature, are compared in salmonid and non‐salmonid fish.
Two iridovirus isolates from Carassius auratus (L.)
Authors: BERRY E. S. , SHEA T. B. , GABLIKS J.
Published: April 2006

Abstract. Two new viruses, goldfish virus‐1 (GFV‐1) and goldfish virus‐2 (GFV‐2), were isolated from swimbladder cultures prepared from healthy Carassius auratus (L.). The isolates were sensitive to pH, heat, and chloroform but stable to freezing and thawing. Treatment with IUDR, Feulgen staining and acridine orange staining indicated that the viruses contain double‐stranded DNA. Electron microscopy revealed enveloped virions of 180 nm enclosing icosahedral capsids of 120 nm. Viral growth was studied by light and electron microscopy and infectivity assays. Virions were assembled in cytoplasmic inclusion bodies and apparently released through cell degeneration. Infectious virus was first produced at 24 h post‐infection. Progressive cytopathology was observed leading to cell ghosts by 96 h post‐infection. The results suggest tentative placement of the viruses in the family Iridoviridae.
Studies into the possible protozoan aetiology of swimbladder inflammation in carp fry
Authors: CSABA G. , KOVÁCS‐GAYER ÉVA , BÉKÉSI L. , BUCSEK MARIA , SZAKOLCZAI J. , MOLNÁR K.
Published: April 2006

Abstract. Laboratory examinations of pond‐reared common carp, Cyprinus carpio L., revealed a close correlation between the prevalence of swimbladder inflammation (SBI), renal sphaerosporosis and infection by C‐blood‐protozoan among the carp fry. In impression smears as well as light and electron microscopic preparations we detected developmental stages of intercellular protozoa, mainly in the loose fibrous tissue of the swimbladder. The parasites multiplied by internal budding so that 20–46 secondary cells were formed in each primary cell and two tertiary cells were formed in each secondary cell. The final stage of development was a unit consisting of a secondary cell enclosing two tertiary cells, i.e. a so‐called triple formation, which bore a close resemblance to the early sporogonic stages of the renal sphaerosporan Sphaerospora angulata Fujita, 1912. Certain morphological similarities and the frequent simultaneous presence of the swimbladder protozoan, C‐bloodprotozoan, and S. angulata in hosts with clinical SBI have led us to postulate that the former two parasites could represent the hitherto unknown presporogonic stages of S. angulata. In view of the pathological changes caused by the parasites in the hosts with clinical SBI, and negative bacteriological and virological findings we have postulated that the swimbladder protozoan is the primary cause of SBI in carp fry.
Spring viraemia of carp virus (SVCV): comparison of immunoperoxidase, fluorescent antibody and cell culture isolation techniques for detection of antigen
Authors: FAISAL M. , AHNE W.
Published: April 2006

Abstract. The sensitivity of the immunoperoxidase (IP) and fluorescent antibody (FA) techniques applied to frozen sections of organs of carp infected with spring viraemia virus (SVCV) was similar, both in respect of the intensity of the reaction and in the detection rate of the antigen. Seven days after a waterborne infection both methods detected the antigen in the kidneys and to a lesser extent in the liver and spleen. Quantification of virus gave a titre of 102.8 to 105.5 TCID50/g of kidney, whereas the agent could not be isolated from liver and spleen tissue. In contrast, at 241/2 days post–infection the viral antigen could be readily detected in liver and spleen but only occasionally in the kidneys using the IP and FA techniques. At this time, liver and spleen showed infectivity titres of 103.8 to 107.2 TCID50/g tissue, whereas the kidneys were found to be free of infective virus. It is concluded that using the IP and FA techniques SVCV can be detected most frequently in the kidneys from 7 to 14 days post–infection and in the liver and spleen from 14 to 24 days post‐infection.
The effects of the use of potassium alum adjuvant in vaccines against vibriosis in rainbow trout, Salmo gairdneri Richardson
Authors: HORNE M. T. , ROBERTS R. J. , TATNER MARY , WARD P.
Published: April 2006

Abstract. A formalized bacterin of Vibrio anguillarum, with and without alum adjuvant, was administered intraperitoneally to rainbow trout under farm conditions. Compared with the normal bacterin the adjuvanted preparation caused pathological changes indicative of chronic peritonitis, substantial early mortalities in 3 cm fish, and to a lesser extent in 20 cm fish, and depressed growth rate. No additional degree of protection against artificial challenge was obtained from its use.
Characterization of exotoxin produced by a shellfish‐pathogenic Vibrio sp.
Authors: BROWN CAROLYN , ROLAND G.
Published: April 2006

Abstract. Broth filtrate of a Vibrio species, isolated from spontaneously occurring epizootics among cultured oyster larvae, Crassostrea virginica (Gmelin), was shown to contain an exotoxin. Bioassays demonstrated that LC50 value was less than 46.6 μg of toxin/l culture of oyster embryos. This quantity was produced by 2.9 × 109 colony‐forming units. Purified toxin showed neither proteolytic nor amylase activity; it did, however, demonstrate bacteriostatic capability. Studies showed that the toxin was heat‐labile and that exposure to heat‐produced toxoid had a beneficial effect on oyster embryonic development. Data revealed that although toxin was inactivated by heating, the bacteriostatic capability of the metabolite was not lost. Molecular weight of the toxin was estimated to be 68000.
Modification of the hyperosmotic infiltration method of vaccination against vibriosis in cultured ayu, Plecoglossus altivelis Temminck and Schlegel
Authors: AOKI T. , KITAO T. , FUKUDOME M. , TAKAHASHI S. , EGUSA S.
Published: April 2006

Abstract. A vaccine solution of a formalin‐killed culture of Vibrio anguillarum cells was observed to be toxic to young ayu when administered by the hyperosmotic infiltration method. The toxin was present in the culture broth. After the toxin was removed from the broth by centrifugation, the fish were dipped in 5.32% NaCl solution for 2 min and then in a solution containing precipitated cells for 3 min. The immunized fish were protected against vibriosis when challenged one month after immersion. The bacterin was administered to ayu by a further two methods, both using lyophilized whole cells of formalin‐killed V. anguillarum. In one method, the fish were placed in a 5.32% NaCl solution for 2 min and then in a solution containing lyophilized cells at 2 g/l of well water for 3 min (two‐step immersion). In the other method, the fish were placed in a 5.32% NaCl solution containing lyophilized cells also at 2 g/l for 3 min (one‐step immersion). A high level of protection against artificial challenge was achieved with either method. No agglutinating antibodies to V. anguillarum were detected in either the serum or mucus of fish dipped in a vaccine solution, a supernatant, or a precipitated solution, one month after immersion. On the other hand, serum titres were detected in fish vaccinated by injection, although no titres were detected in mucus. LD50 values are presented for the virulence of the V. anguillarum strain. Compared to the original strain, virulence increased after the third passage in ayu, but decreased after the thirteenth passage in medium.
Further evidence for the presence of Renibacterium salmoninarum in salmonid eggs and for the failure of povidone‐iodine to reduce the intra‐ovum infection rate in water‐hardened eggs
Authors: EVELYN T. P. T. , KETCHESON J. E. , PROSPERI‐PORTA L.
Published: April 2006

Abstract. Unfertilized, water‐hardened eggs, obtained from a coho salmon, Oncor‐hynchus kisutch (Walbaum), with coelomic fluid containing large enough numbers of the kidney disease bacterium, Renibacterium salmoninarum, to make the fluid cloudy (∼4 × 109 cells/ml), were examined by cultural and histological methods to determine (a) whether an earlier finding of the pathogen in coho eggs could be corroborated, and (b) whether iodine (500 mg/l, in the form of povidone‐iodine) was as effective at ridding them of the intra‐ovum pathogen as it was at freeing them of the extra‐ovum pathogen. The results confirmed that the pathogen does indeed occur within the egg (11–6%‐15‐l % of the eggs were infected in this manner), and suggested a location in the yolk for the pathogen. The findings also indicated that while iodine was very effective in killing the pathogen on the surface of the eggs it was completely ineffective in reducing the prevalence of the intra‐ovum infections. The results point out the need for a method for treating eggs internally and confirm the inadvisability of using eggs from salmonids with cloudy coelomic fluid.
A mortality and associated tissue reactions of chinook salmon, Oncorhynchus tshawytscha (Walbaum), caused by the microsporidan Loma sp.
Authors: HAUCK A. K.
Published: April 2006

Abstract. A systemic infection by the microsporidan Loma sp. became epizootic and resulted in 10% mortality of the population of 337 869 juvenile chinook salmon, Oncorhynchus tshawytscha (Walbaum), from Crooked Creek, Alaska, at Fort Richardson Hatchery, Anchorage, Alaska in the spring of 1980. The microsporidan, forming xenoparasitic cysts (xenomas) of the cell‐hypertrophy tumour type, was found in the gills, arteries, bulbus arteriosus, pseudobranch, choroid gland and kidney. Individual spores were found in cartilage, musculature, liver, arteries, kidney, choroid gland, bulbus arteriosus, ventricle and atrium. Tissue alterations included inflammation, necrosis, and occlusion of arteries; degeneration and necrosis of cartilage and musculature of the tail and head; pericarditis of the bulbus arteriosus; and hyperplasia of heart tissues. Severe infections could impair swimming efficiency, reduce growth rate, and increase mortality after release due to starvation and predation. This represents the first report of microsporidiosis in hatchery‐reared chinook salmon caused by Loma sp.
Histological variations of hepato‐splenic organs from the North Sea dab, Limanda limanda (L.)
Authors: BUCKE D. , WATERMANN B. , FEIST S.
Published: April 2006

Abstract. This study showed variations in the histological appearance of livers and spleens from the North Sea dab, Limanda limanda (L.), sampled during two cruises of the FFS Anton Dohrn (5–15 January 1981 and 12–23 October 1981). Samples were taken from the German Bight, Dogger Bank and Humber/Thames areas of the North Sea. The majority of livers and spleens were assumed to be normal; however, certain histopathological changes were noted which included the abundance and size of melanin–macrophage centres where Fe+++ was demonstrated, sites of focal necrosis, the presence of hepatic nodules, the occurrence of granulomas and hepatic hyperaemia. The areas containing Fe+++ in spleens were quantitatively assessed and found to be increased in size and frequency in dabs sampled from the Dogger Bank. It was also noted that the prevalence of hepatic nodules was higher in dabs from that same area. Although this study does not reveal reasons for the variations in prevalences of anomalies, the pathologies are discussed in relation to habitat and environmental conditions.
Effect of oxidized fish oil, vitamin E and ethoxyquin on the histopathology and haematology of rainbow trout, Salmo gairdneri Richardson
Authors: MOCCIA R. D. , HUNG S. S. O. , SLINGER S. J. , FERGUSON H. W.
Published: April 2006

Abstract. Rainbow trout were fed for 24 weeks on practical diets containing varying concentrations of oxidized fish oil, with or without supplementation of vitamin E and ethoxyquin. Serum biochemistry, haematology and histopathology were investigated to measure the relative protection offered by vitamin E (DL–α–toco–pherol acetate) and/or a synthetic substitute (ethoxyquin), against highly or extremely oxidized oil with peroxide values of 120 or 314mEq/kg oil respectively. Groups fed highly or extremely oxidized oils without DL–α–tocopherol acetate supplementation, and with or without supplemental ethoxyquin, exhibited lower red blood cell numbers, haemoglobin content, haematocrit, and increased haemolysis. In addition, fish from these groups had increased, abnormally developing polychromatocytes, splenic haemosiderosis and hepatic ceroidosis. The results indicate that vitamin E protects better and at lower concentrations than does ethoxyquin, and that supplementation with 33 mg of DL–α–tocopherol acetate/kg is adequate to prevent vitamin E deficiency signs when feeding practical diets containing 7.5 % of a highly oxidized oil. Supplementation with ethoxyquin alone to diets containing highly oxidized oil appeared to exert partial protection, but did not increase the level of protection when added simultaneously with DL–α–tocopherol acetate. The data support the theory of a general antioxidant function for vitamin E, and suggest that mortalities ensuing from vitamin E deficiency are due to the cumulative effects of liver dysfunction and anaemia.
Evidence for lack of antigenic competition among various combinations of Vibrio anguillarum, Yersinia ruckeri, Aeromonas salmonicida and Renibacterium salmoninarum bacterins when administered to salmonid fishes
Authors: AMEND D. F. , JOHNSON K. A.
Published: April 2006

Abstract. Bacterins of Vibrio anguillarum, Yersinia ruckeri, Aeromonas Salmonicida, and Renibacterum salmoninarum were administered alone and in combination to salmonid fishes and the level of protective immunity compared. With each pathogen, the protection obtained with monovalent with A. salmonicida bacterin alone conferred some protection against challenges with Type II V. anguillarum and Y. ruckeri. Also, the combination of A. salmonicida and R. salmoninarum bacterins appeared to potentiate the protection conferred against A. salmonicida. The potential of multivalent vaccines for protecting fish from several diseases appears to be real.
A light and electron microscope study of epitheliocystis in juvenile steelhead trout, Salmo gairdneri Richardson
Authors: ROURKE A. W. , DAVIS R. W. , BRADLEY T. M.
Published: April 2006

Abstract. Ultrastructural analysis of epitheliocystis organisms from gills of anadromous juvenile steelhead trout, Salmo gairdneri Richardson, revealed the presence of several distinct forms. Two oval infectious organisms resembled previously described agents and had chlamydia‐like characteristics. One form had a distinct oval head region from which a tail‐like structure projected. These prokaryotic forms have an ultrastructural appearance which has not been described in previous reports of epitheliocystis. Morphological analyses of gill epithelial cells of S. gairdneri suggest that each cyst remains contained within the cytoplasm of a single host cell.
The enhancement of resistance of the American eel, Anguilla rostrata Le Sueur, to a pathogenic bacterium, Aeromonas hydrophila, by an extract of the tunicate, Ecteinascidia turbinata
Authors: DAVIS J. F. , HAYASAKA S. S.
Published: April 2006

Abstract. Extracts of the tunicate Ecteinascidia turbinate were used in preventing Aeromono hydrophila infection in the American eel, Anguilla rostrata. Intraperitoneal injection of the extract 2 days after bacterial challenge was shown to increase dramatically eel phagocytic activity and resistance to disease. Intravenous injection of the extract 2 days post‐bacterial injection was shown to increase antibody titres. This study helps to substantiate the possible use of E. turbinata extract in treating eel diseases. The exact nature of its protective effect will be dependent on the time and route of its delivery.
Abnormal pituitary‐gonad function in two feral populations of goldfish, Carassius auvatus (L.), suffering epizootics of an ulcerative disease
Authors: MUNKITTRICK K. R. , LEATHERLAND J. F.
Published: April 2006

Abstract. The activity of the pituitary‐gonad axis was examined in goldfish, Carassius auratus (L.), collected from two populations exhibiting epizootics of an ulcerative disease. One population, collected from a pond in Toronto, Ontario, exhibited a significant linear relationship between the extent of lesions and the ovarian state. In a second population, collected from Hamilton Harbour, Lake Ontario, there was no correlation between the high prevalence of oocyte atresia, or the ovarian state with the extent of the ulcerative lesions. Additionally, in the Hamilton Harbour population there were no seasonal changes in the stages of egg development, frequency of mature ova, activity of the pituitary‐gonad axis or gonadosomatic index consistent with gamete release. This apparent spawning failure of the Hamilton Harbour population was supported by the age distribution in the population (no fish younger than 4 years of age were found), and probably accounts for the drastic decline in the capture success of goldfish at that site since 1978. This decline in capture success was correlated with the outbreak of a persistent epizootic of ulcerative disease, suggesting that either the lesions themselves caused the spawning failure, or that the spawning failure and lesion outbreak were both correlated with undetermined changes in the environment, possibly a deterioration in the water quality in Hamilton Harbour.
Influence of dietary selenium on the occurrence of nephrocalcinosis in the rainbow trout, Salmo gairdneri Richardson
Authors: HICKS B. D. , HILTON J. W. , FERGUSON H. W.
Published: April 2006

Abstract Rainbow trout were fed practical‐type diets containing 0.6, 6.6 and 114 μg/g selenium for 16 weeks at approximately 15°C. Fish reared on the highest levels of dietary selenium had a significant reduction in final body weight, feed: gain ratio and increased mortality. Haematocrit, plasma calcium, glucose, and protein levels did not vary significantly. Ninety per cent of the fish fed the diet containing the highest level of selenium developed nephrocalcinosis. Fish with occult nephrocalcinosis had significantly increased levels of kidney calcium and those with overt nephrocalcinosis had significantly increased levels of kidney calcium and magnesium, and liver magnesium. Microscopically, the majority of renal damage was tubular with the renal interstitium becoming inflamed only when tubules degenerated. The pathogenesis of selenium‐induced nephrocalcinosis is discussed.
A viral dermatitis of the smooth dogfish, Mustelus canis (Mitchill)
Authors: LEIBOVITZ L. , LEBOUITZ S. S.
Published: April 2006

Abstract. A viral infection of the smooth dogfish, Mustelus canis (Mitchill), a squaliform shark, is described. The disease was found and observed in wild, laboratory‐maintained and aquaria‐displayed populations of smooth dogfish of the Woods Hole area of Massachusetts during a 2.5‐year period. The disease was characterized by the progressive development of gross and microscopic herpes‐like skin lesions. Electron microscopic examination revealed cellular pathology, viral replication and transport, and virions that conformed to those of herpesvirus infection. This study is the first report of a viral infection in elasmobranchs. The comparative pathology and implication for wild and captive shark populations is discussed.
The toxicity of the cyanobacterium Microcystis aeruginosa to rainbow trout, Salmo gairdneri Richardson
Authors: PHILLIPS M. J. , ROBERTS R. J. , STEWART J. A. , CODD G. A.
Published: April 2006

Abstract. Microcystis aeruginosa is a common cyanobacterium of nutrient‐rich fresh waters. It has been implicated in a large number of poisoning incidents involving wild and domesticated terrestrial animals. The study showed that a pure strain of M. aeruginosa toxic to mice was non‐toxic to rainbow trout immersed in a culture for 10 days. In contrast, when presented by intraperitoneal injections Microcystis caused an acute toxic response with 100% mortality of fish within 36 h. The histopathology of the response is described and contrasted with that to another cyanobacterium, Anabaena cylindrica, which was shown to be non‐toxic by immersion or injection.
A coccolithophorid algal dermatitis of the spiny dogfish, Squalus acanthias L.
Authors: LEIBOVITZ L. , LEBOUITZ S. S.
Published: April 2006

Abstract. Skin diseases of sharks and algal diseases of animals are reviewed. A specific progressive skin disease of wild, laboratory‐maintained and display‐aquaria populations of spiny dogfish, Squalus acanthias L., observed during a 2.5‐year period at Woods Hole, Massachusetts, is described. Skin lesions, from 1mm to over 1cm in diameter, developed in the following sequence: petechial and ecchymotic haemorrhages; dome‐shaped vesicles; larger lesions with central ulceration; and hyperpigmented granulations in the final repair stage. A coccolithophorid algal agent could be demonstrated in skin lesions and is described. Since both sharks and coccolithophorid algae are primitive organisms, the possible evolutionary implications of algal symbionts modified to become pathogens are discussed.
Sanguinicola fontinalis sp nov. (Digenea: Sanguinicolidae): a blood parasite of brook trout, Salvelinus fontinalis (Mitchill), and longnose dace, Rhinichthys cataractae (Valenciennes)
Authors: HOFFMAN G. L. , FRIED B. , HARVEY J. E.
Published: April 2006

Abstract. Sanguinicola fontinalis sp. nov., from the branchial, renal and cardiac blood vessels of brook trout. Salvelinus fontinalis (Mitchill), and longnose dace, Rhinichthys cataractae (Valenciennes), is described. The new species most closely resembles, hut differs from, Sanguinicola davisi of steelhead and rainbow trout, Salmo gairdneri Richardson. The adult differs from all known North American species in having 29–33 lateral tufts of blunt spines. The snail host is Leptoxis (Mudalia) carinata (Bruquière, 1792). Lodged and migrating miracidia caused considerable gill damage in the brook trout, resulting in high mortality when the fish were moved. To remove the hazard, the most severely affected brook trout were destroyed and the ponds drained and disinfected. Adult worms from Pennsylvania brook trout and West Virginia longnose dace were studied, as well as infected snails.
Vibriosis in channel catfish, Ictalurus punctatus (Rafinesque)
Authors: LEWIS D. H.
Published: April 2006

Abstract. An epizootic due to Vibrio anguillarum was observed in channel catfish, Ictalurus punctatus (Rafinesque). Lesions in infected fish included ulceration and petechiae on body surfaces, vent and caudal peduncle. Internally, haemorrhages in liver and kidney were present and the intestinal tract was filled with a clear viscous fluid. Using an isolant recovered during the epizootic, laboratory studies were conducted to determine (a) bacterial dynamics of the agent in blood, kidney and liver and (b) clinical haematologic and biochemical parameters in infected fish. Under conditions of the study, vibrios were apparently sequestered in kidney and liver during initial stages of infection (8–12 h after exposure). Later, bacterial numbers in blood were comparable to those in kidney and liver. Clinical parameters of infected catfish were suggestive of cellular and tissue destruction and renal dysfunction. Based upon data of the present study and those of others, vibriosis appears to be a disease in which the agent is localized in select tissues. Secondary septicaemia may be incidental to factors which compromise host defences.
Histopathology of rainbow trout, Salmo gairdneri Richardson, exposed to diurnally fluctuating un‐ionized ammonia levels in static‐water ponds
Authors: SODERBERG R. W.
Published: April 2006

Abstract. Rainbow trout, Salmo gairdneri Richardson, were reared intensively in nine aerated static‐water ponds. Dissolved oxygen concentrations were maintained above 5 mg/l and un‐ionized ammonia (NH3) levels were monitored in all ponds. Fish were removed periodically and gill, liver and trunk kidney samples were removed for histological examination. Average NH3 concentrations did not exceed a previously reported chronically toxic level, but average daily maximum concentrations exceeded this level in all but two ponds. Gills exhibited lesions characteristic of those attributed to ammonia exposure in all ponds and fish with the most damaged gills had livers demonstrating reduced glycogen vacuolation. No histological changes were noted in kidney tissue. Because gills were damaged even though average NH3 levels were quite low, it is recommended that research in static water carefully consider the cyclical nature of NH3 concentrations.
Histopathology of bullminnows, Fundulus grandis Baird & Girard, infected with a non‐haemolytic group B Streptococcus sp.
Authors: RASHEED VICTORIA , LIMSUWAN C. , PLUMB J.
Published: April 2006

Abstract. Histopathological changes in bullminnows, Fundulus grandis Baird and Girard, experimentally infected with a non‐haemolytic group B Streptococcus sp. were studied. Following experimental exposure to the Streptococcus sp. approximately 40% of the fish developed exophthalmia, dropsy or petechial haemorrhage along the abdomen. The exophthalmic eye showed haemorrhage with neutrophil infiltration. The liver was oedematous and hepatocytes were atrophied, accompanied by a decrease in glycogen and increases in vacuolization, hyaline droplet degeneration and necrosis. The spleen was congested and cells of the sheathed artery were necrotized.
Heteropolaria colisarum Foissner & Schubert, 1977 (Protozoa: Epistylididae) of North American freshwater fishes
Authors: FOISSNER W. , HOFFMAN G. L. , MITCHELL A. J.
Published: April 2006

Abstract The peritrichous ciliate ‘Epistylis sp.’ involved in the‘red‐sore’ disease of various North American freshwater fishes is identified as Heteropolaria colisarum Foissner & Schubert, 1977. Its morphology is redescribed from observations of living and silver‐stained organisms and biometrically analysed individuals. Extended zooids can be easily identified by their highly characteristic (elongated) body. Silver impregnations show a very high number of silverlines and a band‐like, irregularly formed macronucleus. The genus Heteropolaria belongs to the family Epistylididae and is characterized by the eccentric location of the scopula of the swarmer and a peculiar myoneme in the peristomal disc that branches off the myoneme of the peristomal collar. Autochthonous occurrences of this species are known only from North America. In Europe only the related species H. lwoffi has been found. Histological sections give some evidence that the terminal platelet of the stalk is embedded in the dermal epithelium. This suggests that H. colisarum could be a parasite rather than an epizoon and that the often associated bacterium Aeromonas hydrophila is a secondary invader. However, further studies are necessary. Experiments showed a high infectivity of the ciliate and no host specificity. These characteristics are supported by the observations of other researchers. Preliminary laboratory tests showed that a single treatment with salt solution (NaCl) at a rate of 1.5% for 3h controlled H. colisarum.
Necrosis of the hepatopancreas in Penaeus monodon and P, stylirostris (Arthropoda, Decapoda) with red disease
Authors: LIGHTNER D. V. , REDMAN R. M.
Published: April 2006

Abstract The histopathology of red disease was studied in samples of Penaeus monodon from a commercial prawn farm in the Philippines and in a single pond–reared adult P. stylirostris from Hawaii. The principal lesion type observed in prawns from both locations was a marked atrophy and necrosis of the hepatopancreas that was accompanied by an intense cellular inflammatory response. Less commonly, melanized cellular inflammatory lesions were observed in the antennal gland, mandibular organ, gonads, midgut and gills. The aetiology of red disease is unknown, but because of the similarity of hepatopancreatic lesions in red disease to those observed in aflatoxicosis, mycotoxins (or other microbial toxins) present in rancid or spoiled feeds or in the detritus of organically rich ponds are suggested as its cause.
Chronic glomerulonephritis in returning fall chinook salmon, Oncorhynchus tshawytscha (Walbaum), from the Rogue River, Oregon
Authors: MEYERS T. R. , McPHERSON B. P.
Published: April 2006

Epizootic mortalities of returning adult Rogue River fall chinook salmon, Oncorhynchus tshawytscha (Walbaum), were first observed in 1978. These mortalities reached approximately 76% in 1979 and declined to 30‐‐50% in 1980 and less than 10% in 1981 and 1982. Histopathological examination of kidneys from moribund returns in 1981 and 1982 showed a diffuse chronic glomerulonephritis (GN) in 83% and 30% of the fish examined, respectively. In most cases glomerular damage was severe enough to cause morbidity from osmoregulatory failure. The lesion was markedly similar to immune complex‐mediated glomerular disease in higher vertebrates, but tissues for further ultrastructural examination and diagnosis were not processed. Giemsa‐stained sections also revealed unidentified sporozoan‐like vegetative stages encysted within the extracellular mesangial matrix of glomeruli in both GN and normal kidneys. Although probably incidental to the glomerular lesion, the causal relationship of the organism to GN remains unknown until further investigation. Glomeruli of outmigrating Rogue River fall chinook salmon smolts collected in 1983 were normal and free of the organism.
Epidermal hyperplasia of walleye, Stizostedion vitreum vitreum (Mitchill), associated with retrovirus‐like type‐C particles: prevalence, histologic and electron microscopic observations
Authors: YAMAMOTO T. , KELLY R. K. , NIELSEN O.
Published: April 2006

Epidermal hyperplasia consisting of discrete translucent raised outgrowths of cells were observed on the skin of walleye, Stizostedion vitreum vitreum (Mitchill), during their spawning period in the spring. The cells constituting the hyperplastic growths were limited to the epidermal layer, and were associated with surface budded, 120‐nm‐diameter, retrovirus‐like particles located in the expanded intercellular spaces. These tumour‐like growths were distinct from the other virus‐associated skin lesions of walleye including dermal sarcoma, lymphocystis disease and herpesvirus‐associated hyperplasia. Lesions could be differentiated by careful observation in the field and comparison of portions of each growth by histologic and electron microscopic observations.