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1.
Abstract Vascular corrosion casting methods were used to elucidate the pathological effects of X-cell disease on the blood supply to the gills of the Antarctic teleost, Pagothenia borchgrevinki (Boulenger, 1902). Afferent and efferent branchial arteries were patent in X-cell diseased fish; however, the blood supply to the lamellae was markedly reduced or obliterated in areas in which there was a predominance of X-cells. The present authors believe that the tissue hyperplasia associated with X-cell disease results in the compression of the lamellar vascular bed which leads eventually to the occlusion of vessels.  相似文献   

2.
Abstract. An autoradiographic study of the various types of neoplastic lesions in the skin of Pacific English sole Parophrys vetulus Girard was performed using peritoneally injected tritiated thymidine. The epidermis offish is mitotically active at all cell levels, the most important being the supra-basal layer. In the hyperplastically growing epidermis of the English sole covering connective tissue nodules and in the papillating epidermis prior to formation of enlarged ovoid cells (X-cells), the supra-basal layer also shows the greatest degree of labelling. Parallel to the appearance of these X-cells, which are characteristic of the skin tumours in Pacific flatfish, the distribution of DNA-synthesizing cells is altered. In the tumour areas which are more or less filled with X-cells the 'envelope cells' are labelled throughout with a uniform frequency. On the other hand, the directly adjacent X-cell free areas are labelled with a greater than average frequency.  相似文献   

3.
Abstract. The dab, Limanda limanda (L.), is a common species of flatfish found in the shallow waters of the North Sea, particularly in inshore regions. Because of its distribution and habits, it is a useful species for investigations into the biological effects of marine pollution; it is also susceptible to certain, easily-detectable, gross diseases, including a variety of hepatic lesions, some of which are putative neoplasias. Investigations over the past 10 years on the histopathology of dab livers, have revealed that many lesions are associated with parasitic infections or trauma, and others include the presence of basophilic foci and putative adenoma as well as cell storage changes. The significance of these lesions is discussed in relation to other biological and physical data, and the necessity for histological evaluation is emphasized.  相似文献   

4.
Skin ulcerations rank amongst the most prevalent lesions affecting wild common dab (Limanda limanda) with an increase in prevalence of up to 3.5% in the Belgian part of the North Sea. A complex aetiology of these ulcerations is suspected, and many questions remain on the exact factors contributing to these lesions. To construct the aetiological spectrum of skin ulcerations in flatfish, a one‐day monitoring campaign was undertaken in the North Sea. Fifteen fish presented with one or more ulcerations on the pigmented and/or non‐pigmented side. Pathological features revealed various stages of ulcerations with loss of epidermal and dermal tissue, inflammatory infiltrates and degeneration of the myofibers bordering the ulceration, albeit in varying degrees. Upon bacteriological examination, pure cultures of Vibrio tapetis were retrieved in high numbers from five fish and of Aeromonas salmonicida in one fish. The V. tapetis isolates showed cross‐reactivity with the sera against the representative strain of serotype O2 originating form a carpet‐shell clam (Ruditapes descussatus). Moreover, the A. salmonicida isolates displayed a previously undescribed vapA gene sequence (A‐layer type) with possible specificity towards common dab. Further research is necessary to pinpoint the exact role of these agents in the development of skin ulcerations in common dab.  相似文献   

5.
Abstract. In an effort further to define the current health status of demersal fish in the Bering Sea, 36 618 fish captured by otter trawl during 1976 were examined for pathological conditions. Of the 26 species examined, 22 were found to have no detectable abnormalities. The four species with abnormalities were Pacific cod Gadus macrocephalus Tilesius with pseudobranchial tumours and skin lesions, walleye pollock Theragra chalcogramma (Pallas) with pseudobranchial tumours, yellowfin sole Limanda aspera (Pallas) with lymphocystis, and rock sole Lepidopsetta bilineata (Ayres) with epidermal papillomas. The prevalence, geographical distribution and biological and pathological characteristics of affected individuals were determined.
Pseudobranchial tumours of both Pacific cod and walleye pollock were occasionally found to be invasive. Fish bearing these tumours were distributed throughout the sampling area. The epidermal papillomas on rock sole resembled similar tumours found on several flatfish species along the West Coast of North America. The distribution of this disease appeared to be depth related. The virus-caused lymphocystis growths were located on the 'blind' side of yellowfin sole. The highest frequencies of fish with lymphocystis were in the south-eastern Bering Sea. Two main types of skin lesions were seen on Pacific cod: ulcers and ring-shaped lesions. Isolates of bacteria ( Pseudomonas sp.) were routinely obtained from the cod ulcers and may be the cause of this disease. The ring-shaped skin lesions, when examined microscopically, contained unidentified epidermal basophilic bodies.  相似文献   

6.
Fish in a population of Pagothenia borchgrevinki in McMurdo Sound, Antarctica, are affected by a gill disease (X-cell disease) which causes tissue hyperplasia that results in a decreased gill surface area and an increased water/blood diffusion distance. P. borchgrevinki acquires 95% of its oxygen via the gills, but damage to the gills by X-cell disease did not affect this function. There was no compensatory shift to cutaneous respiration. X-cell disease reduced the ability for oxygen uptake at low ambient PO 2 and the decreased uptake was related to the extent of the disease. O 2 max was greatly reduced in X-cell affected fish and substantially reduced their aerobic potential. This effect may impair the ability of diseased fish to catch prey and avoid predators.  相似文献   

7.
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.  相似文献   

8.
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.  相似文献   

9.
Abstract. Pale and swollen gills were observed in 23 of 240 Laval's eelpouts, Lycodes lavalaei Vladykov and Tremblay (Perciformes), taken from several locations off the coasts of Newfoundland and southern Labrador. Light microscopic study of histological sections revealed clusters of unidentified cells ('X-cells') in the basal region of secondary gill lamellae and extending along the latter, between the epithelium and lamellar capillaries. In the electron microscope two types of X-cells were enclosed in a network of cytoplasmic processes from dense 'envelope' cells. Both types of X-cells were bound by a densely-coated limiting membrane and had nuclei with large, dense nucleoli, numerous mitochondria with short vesicular cristae, lipid inclusions, abundant smooth endoplasmic reticulum and small dense inclusions. The Type II X-cells were larger, contained a much greater concentration of lipid and small dense inclusions, and an additional inclusion with a dense core surrounded by a light halo. The X-cells are compared with strikingly similar cells described from epidermal and pseudobranch tumours of marine fish. Although transformation of a host cell by virus or possibly pollution has been suggested, neither the nature nor the origin of the X-cells can be determined.  相似文献   

10.
Abstract. Cultured turbot Scophthalmus maximus (L.) from three farms at Hunterston, Scotland were found to be infected with Haemogregarina sachai . Up to 6% of some populations were affected with gross tumorous lesions of the musculature and viscera. The lesions consisted of necrotic tissue with a caseous centre. Histologically, there was an accumulation of parasitized reticulo-endothelial cells, cell debris and pyknotic nuclei. Parasitaemias of up to 36% of all blood cell types were observed. The majority of infected cells were neutrophils and monocytes. Infected leucocytes were hypertrophied. There was an erythrocytopenia of infected fish with increases in erythroblasts, monocytes and neutrophils but a decrease in thrombocytes and lymphocytes. Transmission experiments between fish were unsuccessful.  相似文献   

11.
Abstract. Sea lampreys handled for other research projects were examined for the presence of tumours. Nine tumours were found including: an ectopic notochordal mass, an epidermoid cyst, an ectopic paranotochordal haematopoietic myeloid mass, and six teratomas. The composition of these sea lamprey tumours did not differ significantly from that of similar lesions in higher vertebrates and thus they were similarly classified. The prevalence of tumours in our specimens was relatively high (1:19).  相似文献   

12.
A numerical circulation and transport model system was used to simulate the dispersion of larvae of blue whiting, Micromesistius poutassou (Risso) in the eastern North Atlantic. The area of the model extends from the northern Bay of Biscay to the Norwegian Sea and covers the shelf-edge and adjacent waters at a horizontal resolution of around 20 km in 16 vertical layers. Larval input data were based on the long-term mean distribution, abundance and seasonal occurrence of larvae, derived from historical information. The circulation model was run using tidal forcing and climatological density fields as well as both climatological meteorological forcing and actual six-hourly wind stress fields for 1994 and 1995. Transport from the main spawning areas to the west of the British Isles and north of Porcupine Bank was associated with currents along the shelf-edge and in the Rockall Trough. Tracers were either dispersed to the north and north-east along the shelf-edge, extending into the northern North Sea and Norwegian Sea, or were retained in the Rockall Gyre and over Porcupine Bank. A less intense southerly flow from Porcupine Bank was observed both under climatological conditions and in the 1995 simulation, when winds were more variable than in 1994. The results based on the 1995 meteorological conditions showed the most extreme retention of tracers in the Rockall Trough/shelf-edge area west of Scotland and a low penetration of tracers onto the shelf. These results are discussed in relation to the observed distribution of 0-group juveniles and to indices of year-class strength – in particular, in relation to the 1995 year class, which is the highest year-class estimate of blue whiting on record.  相似文献   

13.
Recent trends in the abundance, distribution and growth of bluemouth in Scottish waters are described. The observations are all based on an ecologically important time‐series database of trawl surveys conducted annually between 1925 and 2004 by Fisheries Research Services, Aberdeen. We examine the period 1985–2004 in detail. Bluemouth abundance has increased over the last decade both along the continental shelf west of Scotland and in the North Sea. In 1991 bluemouth appeared in the northern North Sea as a distinct cohort, with total lengths ranging between 6 and 8 cm. 1991 was a year of exceptional Atlantic inflow into the North Sea, and it is likely that the bluemouth used this water mass as a highway, entering from the north and west as small individuals. The fish from 1991 grew steadily and formed a distinct length mode that we track here until its disappearance in 2002. In the first few years following this influx, bluemouth were recorded all around the northern North Sea, but since 1997 numbers have declined and its distribution has shrunk into one of two International Council for the Exploration of the Sea (ICES) statistical rectangles (39F1 and 40F2) which are positioned in the central part of the North Sea. Since 1991 only one subsequent and relatively minor immigration of bluemouth into the North Sea has taken place, in 1998. The composition of the North Sea bluemouth population as a single cohort allows its spatial distribution, expansion and growth rate to be charted, discussed and described.  相似文献   

14.
Recent reports of the isolation of infectious salmon anaemia virus (ISAV) from Atlantic salmon, Salmo salar L., affected by haemorrhagic kidney syndrome (HKS) suggest that ISAV can cause severe renal haemorrhage and necrosis in addition to well-known pathognomonic hepatocellular necrosis and haemorrhage. The prevalence of ISAV-induced pathognomonic renal HKS lesions and their correlation to pathognomonic hepatic lesions of infectious salmon anaemia (ISA) is not known. The present experimental infection of Atlantic salmon with a Canadian isolate of ISAV found that pathognomonic hepatic ISA lesions were present in 90.6% and pathognomonic renal HKS lesions in 78.1% of fish which died after the experimental challenge. Both pathognomonic hepatic ISA lesions and pathognomonic renal HKS lesions were found together in 65.6% of fish which died after ISAV challenge. The present study clearly demonstrates that ISAV can cause a very high prevalence of both HKS and ISA pathognomonic lesions.  相似文献   

15.
Abstract. Two Myxobolus species, M. pseudodispar and M. ellipsoides , and two Myxidium species, M. rhodei and M. pfeifferi , were found in roach, Rutilus rutilus L., from three different locations in northern Greece, northern England and Scotland. Their prevalence, distribution in the host and pathology were studied. In the ease of M. rhodei , the pathological changes were quantitatively evaluated by computer-based image analysis, and the results expressed in terms of area and volume of organs affected. The pathology of M. pfeifferi was associated with trophozoites in the bile duets and the infection ranged from mild to severe. In the severe eases, degeneration of duetal mucosa sometimes progressed to focal hepatitis. Myxidium rhodei was found in the kidneys as large cysts containing mature and immature spores (Type A cysts), and less often, in the form of small concentric cysts (Type B) which contained no obvious spores but which were characterized by a marked host response giving the appearance of focal granulomas. Type A cysts were also found in liver and spleen, and Type B cysts in the heart. Trophozoites of M. rhodei were observed in only a few eases and occurred in enlarged renal corpuscles in which the capillary tuft was atrophied and compressed. The pathology of M. rhodei was significant due to the enlargement of glomeruli from four to seven times their normal size and with an estimated increase in volume of 54 to 78 times. In addition to the functional damage to the glomeruli, there was also damage of the surrounding interstitial tissue and tubules as a result of the pressure from these enlarged glomeruli. The two myxobolid species were considered to be mainly specific to the kidney with no serious pathology in this organ, but caused significant pathology in the muscles ( M. pseudodispar ) and gills ( M. ellipsoides ).  相似文献   

16.
Sequence data from salmonid alphavirus (SAV) strains obtained from farmed marine Atlantic salmon, Salmo salar L. , over a 20-year period between 1991 and 2011 was reviewed to examine the geographical distribution of the genetically defined SAV subtypes in twelve regions across Ireland and Scotland. Of 160 different Atlantic salmon SAV strains examined, 62 belonged to subtype 1, 28 to subtype 2, 34 to subtype 4, 35 to subtype 5 and 1 to subtype 6. SAV subtypes 1, 4 and 6 were found in Ireland, while subtypes 1, 2, 4 and 5 were found in Scotland. In the majority of regions, there was a clear clustering of subtypes, with SAV subtype 1 being the dominant subtype in Ireland overall, as well as in Argyll and Bute in Scotland. SAV subtype 2 predominated in the Shetland and Orkney Islands. The emergence in Atlantic salmon of subtype 2 strains typically associated with sleeping disease in rainbow trout in Argyll and Bute, strongly suggesting transmission of infection between these species, was noted for the first time. SAV subtype 4 was the most common subtype found in the southern Western Isles, while SAV subtype 5 predominated in the northern Western Isles and north-west mainland Scotland. No single strain was dominant on sites in the western Highlands, with a number of sites in this region in particular having more than one subtype detected in different submissions. The significance of these results in relation to aspects of the epidemiology of infection, including transmission, biosecurity and wildlife reservoirs are discussed and knowledge gaps identified.  相似文献   

17.
The distribution of juvenile fish in Norwegian waters in spring and summer provides evidence that some of these are transported into Norwegian coastal waters from spawning grounds outside the ecosystems which comprise the central and northern Norwegian coast, the Barents Sea and the Spitsbergen area. The relevant species are capelin (Mallotus villosus Müller), haddock (Melanogrammus aeglefinus L.), herring (Clupea hareri' gus L.) and saithe (Pollachius virens L.). A substantial part of the saithe and haddock stock along the central and northern Norwegian coast is considered to be recruited from spawning grounds in the northern North Sea. A contribution of these species from the spawning grounds around the Faeroe Islands and west of Scotland may also occur in some years. Herring from the northern North Sea are found scattered off the Norwegian coast north to 70oN. It seems likely that pelagic species such as capelin and herring are transported by the prevailing currents from Iceland.  相似文献   

18.
In the present study, a total of 150 samples including 50 salted anchovy, 50 raw anchovy, and 50 raw mussel samples collected from the retailers and small-scale producers in Samsun province from the Black Sea region of Turkey were analyzed; and 12% (6/50), 2% (1/50), and 2% (1/50) of the samples, respectively, were found to be contaminated with L. monocytogenes. According to the serotype distribution, six salted anchovy and one of the raw fish samples were contaminated with L. monocytogenes 1/2b (or 3b). In one raw mussel, both L. monocytogenes 1/2b (or 3b) and 4b (or 4d or 4e) serotypes were detected.  相似文献   

19.
Abstract A cutaneous ulcerative disease (red spot) in sea mullet, Mugil cephalus L., from the Clarence River, New South Wales, Australia, was first reported in 1972. In this study, reports of disease outbreaks have been compared with rainfall and river flow records for the period from 1972 to 1988. Detailed disease prevalence, rainfall, river flow and water quality data were compared for the period from 1985 to 1988. Significant correlations between weekly rainfall in the lower catchment and the prevalence of early stage lesions have been found. Progression to later stages of the disease occurred after rainfall and high river flows, which also caused rapid changes in various water-quality characteristics such as salinity, temperature, dissolved oxygen, pH and turbidity. Organochlorine insecticide residues were not found to be associated with the disease in this area. The rainfall record since 1902 does not explain the absence of earlier reports of the disease. It is postulated that extensive structural developments for flood mitigation purposes and the increase in agricultural cultivation in the lower Clarence catchment during the last 20 years may be factors associated with the onset of the early stage of red spot disease. Fish in this early stage of the disease may then develop dermal ulcers under the stressful river conditions typically present during the autumn (high rainfall) season.  相似文献   

20.
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