共查询到20条相似文献，搜索用时 16 毫秒
1.
Cutaneous myxidiosis in European eel,Anguilla anguilla (Linnaeus, 1758): histopathology,histochemistry and laminin immunohistochemistry 
下载免费PDF全文
下载免费PDF全文 Histopathology, histochemistry and immunohistochemistry of the integument of European eel, Anguilla anguilla (Linnaeus, 1758), infected by Myxidium sp. are reported. Skin samples from affected and unaffected eels were dissected, formalin fixed, paraffin embedded, sectioned and stained with H&E, Periodic acid–Schiff's staining method, Alcian Blue 8 GX pH 2.5/Periodic acid–Schiff's and McCallum‐Goodpasture's Gram stain. Moreover, immunohistochemistry was performed using a primary polyclonal laminin antibody. Histologically, cysts (diameter 2–3 mm) were observed mainly under the scale pockets, encircled by a thin collagen layer, lined by elongated, flattened fibroblasts and containing bipolar, PAS‐ and Gram‐positive spores with opposite polar capsules. The epidermis stretched by the underlying cyst appeared dysplastic, thinned with a significant reduction in mucous cells number. Only inconsistent and aspecific inflammatory reaction was noted around the cysts at the dermis/epidermis interface. Intense laminin‐like protein immunolabel was documented in the plasmodial ectoplasm and related to host anergia. This was the first report of laminin immunolabel in a member of the Myxozoa. Epidermal dysplasia represents likely an aspecific response against the underlying tensile force exerted by the developing parasite cyst, while fibroblast and collagen encapsulation denote a parasite‐driven host response protecting, rather than harming, the encircled parasite. 相似文献
2.
The parasite, Anguillicola crassus is a non-native species that infects naive European eels, Anguilla anguilla, and causes pathological damage to the swimbladder, potentially compromising their ability to cope with hypoxic conditions. This study aimed to elucidate whether anguillicolosis exacerbates the stress responses to exposure to hypoxic water, conditions that have been implicated in mass mortalities of wild infected European eels. Blood parameters in infected and uninfected eels were measured during exposure to severe hypoxia over an 8-h period. Infected fish showed significantly higher levels of plasma cortisol compared with uninfected eels after 4 h of hypoxia. Uninfected fish showed an almost twofold increase in plasma glucose after 8-h exposure to hypoxia but infected fish showed no significant change, so that the plasma glucose concentration was significantly higher in uninfected eels than in infected eels. Both groups showed similar elevations in blood haematocrit, suggesting a similar catecholamine response in infected and uninfected eels. The lack of a hyperglycaemic response in infected eels, despite indirect evidence of a catecholamine response to hypoxia, may reflect an increase in glucose turnover. The data suggest that anguillicolosis results in a significantly greater corticosteroid stress response to hypoxia accompanied by a higher metabolic cost. 相似文献
3.
Acquired resistance of the eel, Anguilla anguilla L., to challenge infections with gill monogeneans 总被引：1，自引：0，他引：1
Abstract. The European eel, Anguilla anguilla L., is able to respond to infections with ectoparasitic gill monogeneans of the genus Pseudodactylogyrus Gussev, 1965. A primary infection offers the host a relative resistance to challenge infections. The relative protection was detected at both 14 and 33 days after mebendazole termination of the primary infection by a significantly greater parasite reduction in previously infected eels compared to non-primed eels. No complete immunity was obtained. 相似文献
4.
S. COSTA‐DIAS E. DIAS J. LOBÓN‐CERVIÁ C. ANTUNES J. COIMBRA 《Fisheries Management and Ecology》2010,17(6):485-492
Abstract Infection by the parasitic nematode Anguillicoloides crassus Kuwahara, Niimi & Itagaki, in a wild riverine stock of European eel, Anguilla anguilla (L.), in a near pristine river was investigated. Samples were collected on a seasonal basis in distinct habitats along the river gradient. This study highlighted the presence of the parasite and completion of the whole life cycle in eels from the Río Esva. Infection levels by A. crassus were high at three sites between the mid river to the estuary and also varied among seasons. Condition of eels was lower at upstream sites compared with downstream locations. Although high‐quality, environmental conditions in the Río Esva may buffer the effects of A. crassus on eels, potential impacts and limiting factors for the parasite are discussed. 相似文献
5.
European eels reaching the silver stage stop feeding in freshwater and during their spawning migration to the Sargasso sea (6000 km at least in the Ocean). The total duration of this exceptional fast is not well known. Few data are available on the general condition and the endocrine responses to starvation of migrating eels. In this study male (silver) and female (yellow and silver) eels were kept in freshwater without food for various lengths of time. Animals were killed after 7 months to 3 or 4 years. After a gradual decrease, the final body weight was reduced by 84% in males (52 months) and 67–69% in females (up to 4 years). The condition factor (K) followed a parallel curve. In the pituitary gland, GH cells were hypertrophied and highly stimulated. Their cross-sectional area was negatively correlated to K. Large GH cells remained well immunostained with an anti-eel GH serum after 7 to 12 months of starvation. In the leanest eels, the immunostaining was often reduced and many GH cells appeared degranulated, suggesting a low hormonal storage. In contrast, SL cells were reduced in size and number in the anterior half of the neurointermediate lobe (NIL), but showed a more heterogeneous picture in the caudal portion. GH and SL cell activities seemed to be negatively correlated in starved fish and controlled by different mechanisms. GH appears to play a major role in the long-term survival of fasted eels; SL does not seem to be involved. 相似文献
6.
Anthropogenic spreading of anguillid herpesvirus 1 by stocking of infected farmed European eels,Anguilla anguilla (L.), in the Schlei fjord in northern Germany 下载免费PDF全文
下载免费PDF全文 The Schlei fjord in northern Germany is the recipient water of a comprehensive eel, Anguilla anguilla (L.), stocking programme. Since 2015, stocked eels become alizarin red S marked, but to date no control mechanism is implemented in this stock enhancement measure to prevent anthropogenic spreading of diseases. Consequentially, it was possible that farmed stocking cohorts of 2015 and 2016 (in total ca. 1040 kg) were subsequently tested positive for anguillid herpesvirus 1 (AngHV 1). For this study, 100 eels [total length (TL) 24.3–72.9 cm, age ca. 1–6 years] were caught in 2016 and investigated with regard to AngHV 1 infection, parasite load (Anguillicoloides crassus) and body conditions. 68% of the eels were found to be virus positive while larger specimens were more often infected. In addition, a fitted generalized linear model (area under the curve = 0.741) demonstrated that an increase in individual TL is accompanied with an increased risk of clinically relevant virus loads. Anguillicoloides crassus turned out to be an important stressor for eels, because parasite and virus load revealed a significant positive correlation. The results of this study evidently show the urgent need of a disease containment strategy for eel stocking programmes. 相似文献
7.
Kennedy CR 《Journal of fish diseases》2007,30(6):319-334
Although 63 and 55 species of helminths have been reported from each species of Atlantic eel and from 29 to 19 for each species of Pacific eel only the monogeneans Pseudodactylogyrus bini and P. anguillae and the nematode Anguillicola crassus, originally specific to species of Pacific eels, can be considered serious pathogens. None of the three are normally pathogenic to their preferred natural eel host species in the wild. Pseudodactylogyrus spp. only cause serious local gill damage when present on a host in large numbers under optimal conditions that facilitate transmission. This is the case in eel aquaculture, where infections can be controlled by drugs. Anguillicola crassus is only pathogenic to Anguilla anguilla and A. rostrata when Atlantic eels are introduced to the far east or when the parasites have been introduced to Europe. Here the parasite life cycle differs in that A. crassus can infect a wide range of intermediate hosts, employ paratenic hosts and survive as larvae for months in the swimbladder wall. This makes it an excellent colonizer. Its major pathogenic effects on eels result from haemorrhaging in, and thickening of, the swimbladder wall. It reduces the oxygen concentration in the swimbladder, reducing its ability to function as a hydrostatic organ, and increases the stress response of eels. In shallow lakes at warm temperatures this can result in mass mortalities. It is also feared that the parasite affects the ability of eels to migrate to the Sargasso Sea and so contributes to the decline in eel populations. Control by drug treatment is possible in culture, but not in the wild. 相似文献
8.
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. 相似文献
9.
Kohma Arai Hikaru Itakura Akihito Yoneta Tatsuki Yoshinaga Fumiaki Shirotori Kenzo Kaifu Shingo Kimura 《Fisheries Science》2017,83(5):735-742
To investigate the presence of non-native anguillid eels in Japanese waters, 141 eels were collected from seven sampling sites throughout the Tone River system. Genetic species identification showed an extraordinary dominance of the non-native European eel Anguilla anguilla in the uppermost site of the study area. Estimation of age from otoliths suggested that the European eels were introduced into the river in the 1990s, corresponding to previous reports from other Japanese water systems. Comparison of the von Bertalanffy growth curve parameters indicated that the European eels caught in the Tone River system appeared to have a similar or even higher growth rate than the same species in the original habitats in Europe. The long-term inhabitation and the normal development of European eels in Japanese waters suggest that regulations prohibiting the release of non-native eels and safeguards against accidental escape from culture ponds must be strictly maintained in order to ensure the conservation of the native Japanese eel. 相似文献
10.
Palstra AP Guerrero MA de Laak G Klein Breteler JP van den Thillart GE 《Fish physiology and biochemistry》2011,37(2):285-296
The onset of downstream migration of European eels is accompanied by a cessation of feeding and the start of sexual maturation
which stresses the link between metabolism and sexual maturation, also suggesting an important role for exercise. Exercise
has been tested with eels in swim tunnels and was found to stimulate the onset of sexual maturation. In this study, we have
investigated the interplay between migration and maturation in the field during the downstream migration of female silver
eels. Temporal changes in migratory status and sexual maturation among silver eels of the upstream Rhine River system over
3 months of the migration season (August, September and October) were determined in biometrical parameters, plasma 17β-estradiol
and calcium levels, oocyte histology and gonadal fat levels. Furthermore, the ecological relevant parameters age as determined
by otolithometry and health aspects indicated by haematocrit, haemoglobin and swim-bladder parasite load were measured. Silver
eels were estimated to be 14 years old. A strong temporal progression in migratory stage was shown over the months of downstream
migration. Catches probably represented a mix of reproductive migrants and feeding migrants of which the ratio increased over
time. Furthermore, this study confirmed our hypothesis linking the migratory stage to early maturation as indicated by enlargement
of the eyes, oocyte growth and fat deposition in the oocytes, exactly the same changes as found induced by exercise but not
ruling out environmental influences. Migrants show extensive fat uptake by the oocytes, probably stimulated by the swimming
exercise. In addition, at least 83% of the silver eels in this spawning run may have suffered from negative effects of swim-bladder
parasites on their swimming performance. 相似文献
11.
Comparative imaging of European eels (Anguilla anguilla) for the evaluation of swimbladder nematode (Anguillicoloides crassus) infestation 下载免费PDF全文
下载免费PDF全文 This study compares diagnostic imaging tools in detecting the parasitic swimbladder nematode Anguillicoloides crassus in Anguilla anguilla (L.) and focuses on ultrasound in an attempt to develop a non‐destructive, field diagnostic test. Ultrasound use could allow the parasite to be diagnosed without decreasing the number of critically endangered European eels through post‐mortem. In the preliminary study, eels were examined with computed radiography, computed tomography, magnetic resonance imaging, 14 MHz high‐end ultrasound and 5 MHz low‐end portable ultrasound, and the results were compared with post‐mortem findings. This ultrasound scanning technique did not produce any promising results. A second batch of eels was examined using the same high‐end and low‐end ultrasounds, but employing a different scanning technique and comparing the results with post‐mortem. This second study, scanning along the midline from below, allowed for the detection of anomalies associated with moderately infected animals. None of the eels used in this study were severely infected; thus, no conclusions can be made regarding the use of ultrasound in those animals. Overall, it was found that none of the techniques were useful in diagnosing mildly infected individuals; therefore, no single diagnostic imaging tool is sensitive enough to replace post‐mortem for definite diagnosis. 相似文献
12.
The effect of foraging and ontogeny on the prevalence and intensity of the invasive parasite Anguillicola crassus in the European eel Anguilla anguilla 下载免费PDF全文
下载免费PDF全文 Infection patterns of the invasive Anguillicola crassus nematode were investigated in a population of the European eel Anguilla anguilla where parasite invasion is very recent, Loch Lomond, Scotland. Intensity levels of the parasite were associated with differences in fish ontogeny and trophic ecology. Although eels foraged on both fish and invertebrates, individuals which were smaller and fed on invertebrates (>70% contribution to diet) were found to contain a greater number of swim bladder parasites compared to larger eel with a predominance of fish (>60% contribution) in their diet. Within affected fish, a significant negative relationship was found between fish length and parasite intensity, with smaller individuals having higher parasite intensity than larger individuals. This study indicates that food intake and infection risk are linked in this recently infected host–parasite system. From a management perspective increasing our understanding of how infection intensity and repeated exposure is linked to resource use in an ecosystem is important for the future management of this endangered species in Europe. 相似文献
13.
《水生生物资源》2001,13(6):411-420
Biological data on glass eels (Anguilla anguilla) were collected during two successive sampling periods from November to March (1996–1997 and 1997–1998) on the Adour estuary. As for other estuaries, decrease in length (mean of 73.5 to 67.4 mm) and weight (mean of 3.5 to 2.6 dg) of glass eels were observed. Weight and length characteristics were used to identify groups of glass eels. These groups were well distinguished during the first sampling period but some overlaps appeared in the second one. Fluctuations of static allometry and similarity coefficients showed successive glass eels arrivals in the lower part of the estuary during the two seasons. We used fluctuations of the index of similarity in the second period to describe arrivals of glass-eels groups. The conjunction of strong floods and weak tide coefficients leads to unfavourable conditions of migration for the glass eels penetrating the estuary. After accumulation of shoals of glass eels in the lower part of the estuary, when hydrological conditions become again favourable, the mixed shoals migrate again by successive ‘waves’, at the rhythm of tides. 相似文献
14.
The late-summer diel activity patterns and space utilization of five Japanese eels, Anguilla japonica, were investigated using an acoustic telemetry positioning system in a shallow brackish lake in western Japan. Eels were highly nocturnal and crepuscular, with 98.1% of positions detected between sunset and sunrise, and were more active during dusk and dawn compared with nighttime, and during full moons compared with other lunar periods. Most diurnal activity occurred during darker conditions, and two individuals extended their activity into the morning, suggesting that overcast skies reduced light intensity and prolonged nocturnal activity into daytime. Individual eels had different home-range patterns, but appeared to rest nearshore during the day, with space utilization expanding offshore at dusk and night, followed by returning to nearshore at dawn. Their home ranges and core activity areas were bordered by the shoreline, with eels tending to exhibit small activity spaces and strong site fidelity. This study provides valuable ecological knowledge about the individual behavior of eels inhabiting a small brackish lake at the northern limit of the natural distributional range of the species along the Sea of Japan, which can contribute to management and conservation of the species.
相似文献15.
鳗鲡疱疹病毒的分离与鉴定 总被引：4，自引：3，他引：1
为获知鳗鲡"脱粘败血病"与病毒的关系,实验用蔗糖密度梯度离心的方法从发病的欧洲鳗鲡内脏器官组织匀浆液中纯化了病毒粒子,负染后利用电镜观察;进一步用EO细胞对病毒进行了分离、培养,并对感染病毒的细胞进行超薄切片,电镜观察;然后,提取病毒DNA,利用鳗鲡疱疹病毒的PCR检测方法对其进行了鉴定。结果显示,接种匀浆上清液的EO细胞出现细胞融合的病变效应;分离病毒的病毒粒子具囊膜,大小约为200 nm;从感染病毒的细胞上清液DNA中扩增出特异性条带,序列测定与比对分析表明,该序列与鳗鲡疱疹病毒欧洲株(AngHV-1)的序列完全一致。研究表明,利用EO细胞分离了一株鳗鲡病毒,经形态观察和DNA分析,确认该病毒为鳗鲡疱疹病毒,命名为AngHV-FJ。该研究为深入开展鳗鲡疱疹病毒的致病机制及鳗鲡"脱粘败血病"的防控研究奠定了重要基础。 相似文献
16.
Abstract. The foregut of eels naturally infected by Epieimeria anguillae (Léger & Hollande, 1922) was studied by light and electron microscopy. It has been established that this parasite, which develops in a characteristic location on the surface of epithelial cells, and was classified on this basis by Dyková & Lom (1981) as a member of the genus Epieimeria , undergoes intracellular merogony and gamogony similarly to other eimerians; however, its sporogony takes place outside the fish or intercellularly. The trophozoites and merogonic and gamogonic stages each develop in a para-sitophorous vacuole which is half embedded in the epithelial cell and protrudes into the intestinal lumen. The parasitophorous vacuote is surrounded by a single membrane; however, towards the intestinal lumen it is covered also by the cell membrane. In its location, Epieimeria anguillae resembles cryptosporidia, but differs from the latter significantly in its relationship with the host cell. 相似文献
17.
为了解不同体色黄鳝的性别与体长、体重的差异,2011年5-7月,于洞庭湖地区随机采集灰色及黄色2种体色共208尾野生黄鳝,并对体长、体重及性别进行测量鉴定。样本中,雌性146尾,雄性62尾,雌雄比例为2.35∶1。其中黄色黄鳝83尾,灰色黄鳝125尾。分析结果表明,黄色黄鳝雌雄个体体重及肥满度均高于灰色群体;黄色黄鳝雌性体长大于灰色雌性,雄性小于灰色雄性。雌雄个体体重与体长的相关系数,黄色黄鳝分别为0.914、0.945,灰色黄鳝分别为0.567、0.438。黄色雌鳝比例随着体长的增加逐渐降低,雄性比例随体长的增加逐渐升高,雄鳝在35 cm以上占优势,40 cm之上雄性仅1尾。灰色雌鳝在40 cm以下占优势。2种体色黄鳝雌性比例与体重变化无明显规律。 相似文献
18.
Yu-Wei Chu Yu-San Han Chia-Hui Wang Wann-Nian Tzeng 《Aquaculture (Amsterdam, Netherlands)》2006,261(4):1230-1238
The sex ratio of wild Japanese eels in the Kaoping River of southwestern Taiwan has been extremely skewed towards females in the recent years. However, the sex ratio skewed towards males after Typhoon Mindulle, July 2, 2004 then recovered to the previous female-dominated status in the following year. To determine why the sex ratio drastically changed, eels captured in the river were examined by both morphologic characteristics and otolith elemental signatures by solution-based inductively coupled plasma mass spectrometry (SB-ICPMS) and laser-ablation ICPMS (LA-ICPMS). Most of the eels collected in the river after the typhoon had a blue-gray colored back, with morphology and sex ratio similar to that of cultured eels, which differed from wild yellow eels which had a green colored back. The chemical signature in otoliths of eels with a blue-gray colored back was similar to that of cultured eels, with significantly lower Sr/Ca ratios but slightly higher Mn/Ca ratios than for wild eels. This confirmed that the reversal in eel sex ratio in the Kaoping River estuary resulted from cultured eels that had escaped from eel farms. Eel farmers estimated that about 30,000 eels escaped during the typhoon, sufficient to reverse the sex ratio of the eels in the river. Furthermore, silver eels caught in the estuary in the winter 2004 were also mostly males. The chemical signature in otoliths of these silver eels was similar to that of escaped cultured eels. Their morphology and mean GSIs, however, were comparable to wild silver eels. Thus, cultured eels that have escaped from eel farms can silver normally in the wild. Consequently, cultured eels may help to balance the sex ratio of the wild eel population and may contribute to the spawning stock of Japanese eel. 相似文献
19.
J. W. COPLAND 《Journal of fish diseases》1983,6(5):451-460
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. 相似文献