Influence of enteric helminths on the distribution of intestinal endocrine cells belonging to the diffuse endocrine system in brown trout,Salmo trutta L

The presence of intestinal helminths in the alimentary canal of brown trout, Salmo trutta L., can alter the number of cells that synthesize modulatory peptides. A total of 167 brown trout were collected from tributaries of the River Brenta (northern Italy), of which 119 (71.3%) specimens were infected with enteric helminths, 28 with the acanthocephalan Pomphorhynchus laevis Müller, 1776 with intensity of infection ranging from 1 to 162 (18.57 +/- 30.79) worms per host and 67 fish with the cestode Cyathocephalus truncatus Pallas, 1781. Intensity of infection with C. truncatus ranged from 1 to 85 (6.87 +/- 12.59) per fish. In 24 fish there were concurrent infections of both species of helminths. The caecal and middle regions of the intestine were the most heavily parasitized. Immunohistochemical tests showed a decrease in endocrine cells (ECs) of the diffuse endocrine system (DES) positive to gastrin, cholecystokinin-8, bombesin and secretin antisera in the intestine of the infected trout. The number of ECs immunoreactive to anti-glucagon serum did not show differences in the digestive tract of uninfected brown trout and in conspecifics parasitized with P. laevis. The density of cells containing glucagon-like material was low in the fish parasitized with C. truncatus. The results suggest that endoparasitic helminths induce alterations in the DES of infected S. trutta.     

豹纹鳃棘鲈消化道粘液细胞的类型与分布

应用AB-PAS染色法对工厂化养殖条件下豹纹鳃棘鲈(Plectropomus leopardus)消化道粘液细胞的类型与分布进行了观察研究。结果显示:豹纹鳃棘鲈粘液细胞在消化道各部位均有分布,不同部位的粘液细胞密度和类型均有差异,豹纹鳃棘鲈消化道粘液细胞可分为Ⅰ型、Ⅱ型、Ⅲ型、Ⅳ型。其中,食道粘液细胞以Ⅲ型为主,胃以Ⅰ型为主,幽门盲囊和肠以Ⅲ型为主,直肠以Ⅲ型和Ⅳ型为主;胃部粘液细胞分布密度最大,达(111.37±21.74)cell·mm~(-2),极显著高于消化道其它部分,直肠、幽门盲囊、肠的粘液细胞分布密度分别为(35.09±8.74)、(30.23±5.37)、(28.00±4.67)cell·mm~(-2),相互之间差异不显著,食道的粘液细胞分布密度最低,为(10.83±1.94)cell·mm~(-2),与消化道其它部分相比差异极显著。另外,消化道各段单位面积内粘液细胞的分泌能力顺序为食道直肠肠幽门盲囊胃。通过对消化道各部位粘液细胞的分类对比可以发现,粘液细胞的类型和分布与其所在部位的功能有密切关系。     

栉孔扇贝外套膜和鳃粘液细胞的类型与分布

采用AB PAS染色法显微观察和分析人工养殖 3龄栉孔扇贝 (Chlamysfarreri,壳长 4 0～ 5 0mm)外套膜和鳃粘液细胞类型与分布规律。结果表明 ,粘液细胞分为 4种类型 ,Ⅰ型呈红色 ,Ⅱ型呈蓝色 ,Ⅲ型呈紫红色 ,Ⅳ型呈蓝紫色。不同部位 ,粘液细胞类型、密度及形态不同 ,这与其功能密切相关。外套膜边缘膜及生壳突起内、外表皮粘液细胞均以Ⅱ型为主 ,密度较小 ,形态主要为梨形、杯形、圆形 ,并多为大型细胞 ;中央膜内表皮以Ⅰ型和Ⅲ型较多 ,形态多为圆形或不规则形 ,外表皮只有Ⅱ型细胞分布 ;鳃轴表皮粘液细胞以Ⅰ型和Ⅲ型为多 ,形态为圆形、杯形或不规则形 ;鳃丝表皮粘液细胞多为Ⅱ型和Ⅳ型 ,形态多为圆形 ,少量为杯形 ;外套膜感觉突起和缘膜突起的表皮中无明显着色的粘液细胞 ,而是被大量棕色颗粒充满     

海湾扇贝消化系统粘液细胞的类型与分布

采用组织化学方法，AB—PAS染色，对人工养殖的1龄海湾扇贝(Argopecten irradians，壳长35—40mm)进行显微观察，发现海湾扇贝唇瓣、口唇、胃、肠、直肠、晶杆囊和肝脏中均有粘液细胞分布，其中，内唇瓣的内表皮和外唇瓣的外表皮粘液细胞数量较多，其中Ⅱ型(AB—PAS染色呈蓝色)最多，Ⅳ型(蓝紫色)次之，Ⅲ型(紫红色)较少，I型(红色)极少；内唇瓣的外表皮和外唇瓣的内表皮粘液细胞仅在每一横褶的皱褶处集中分布，多为Ⅱ型，另有少量Ⅳ型。口唇粘液细胞较多，排列比较紧密，Ⅱ型最多，Ⅳ型次之。胃粘液细胞数量很少，均为Ⅱ型。肠粘液细胞(Ⅱ型)较多，在肠上皮细胞较薄的区域分布密集。直肠粘液细胞(Ⅱ型)较多。晶杆囊粘液细胞(Ⅱ型)仅分布于局部。粘液细胞(Ⅱ型)在肝脏仅有少量分布于输出管壁和外上皮中。     

Mast cells in the gills and intestines of naturally infected fish: evidence of migration and degranulation

Immunopathological and ultrastructural studies were carried out on the gills of bream, Abramis brama, naturally infected with the copepod Ergasilus sieboldi and on the intestine of brown trout, Salmo trutta, infected with the acanthocephalan Echinorhynchus truttae. Infected gills showed extensive tissue damage due to copepod attachment, including hyperplasia, as well as proliferation of mast cells, rodlet cells and mucous cells. In parasitized gills of bream, mast cells were more abundant than in uninfected gills. They were free within the lacunae, as well as outside and inside the blood vessels of the primary lamellae, and made intimate contact with vascular endothelial cells and with neutrophils. In some infected gills, degranulation of mast cells was common. Infected intestines of brown trout had more mast cells than uninfected intestines, and these cells were often in close proximity to, and inside, the capillaries and lying close to fibroblasts of the muscularis layer and stratum granulosum. Intense degranulation of mast cells was encountered in all intestinal layers, especially near the E. truttae body.     

不同摄食状态下南方鲇幼鱼肠道黏液细胞的量化分析

量化分析了南方鲇(Silurus meridionalis)幼鱼在正常摄食节律下摄食前(S0d)、摄食后64 h(S0d-64h)、饥饿16d(S16d)、饥饿32 d(S32d)以及饥饿后首次恢复摄食64 h(S16d-64h,S32d-64h)肠道各类型黏液细胞的反应特征。结果发现,摄食后肠道各部位黏液细胞总数均有一定程度减少,其中前肠减少最为显著(P<0.05);中肠和后肠II型黏液细胞数量显著减少(P<0.05),中肠的III型黏液细胞数量显著增多(P<0.05);肠腔中黏液增多,黏液细胞呈空泡结构。S16d组和S16d-64h组前肠和中肠的I型细胞数量显著减少(P<0.05),III型细胞数量显著增多(P<0.05)。S32d组和S32d-64h组前肠各类型细胞数量以及黏液细胞总数变化不明显(P>0.05);中肠的II型细胞数量显著增多(P<0.05),IV型细胞数量显著减少(P<0.05);饥饿和恢复摄食后肠各类型黏液细胞数目变化不明显(P>0.05)。研究表明,南方鲇幼鱼肠道黏液细胞的摄食反应明显;饥饿胁迫以及恢复摄食后肠道黏液细胞的反应特征与肠道各段的生理功能相适应;面对营养胁迫时,肠道前段能迅速调节黏液细胞的数目,而后肠基本不变,可能是该鱼应对营养缺乏的保护性适应机制。     

Body site matters: an evaluation and application of a novel histological methodology on the quantification of mucous cells in the skin of Atlantic salmon,Salmo salar L.

Mucous cell size and distribution were investigated in the skin of five salmon using a novel stereology‐based methodology: one (48 cm) fish to test 15 tissue treatment combinations on measures of cell area and density on the dorsolateral region and, using the most suitable treatment, we mapped mucous cell differences between body regions on four (52 cm) salmon, comprising a male and a female on each of two diets. The section site, decalcification, embedding medium and plane of sectioning all impacted significantly on mucous cell size, whereas mucous cell density is more robust. There were highly significant differences in both mucosal density and mean mucous cell size depending on body site: the dorsolateral skin of the four salmon had significantly denser (about 8% of skin area) and larger (mean about 160 μm²) mucous cells, whereas the lowest mean density (about 4%) and smallest mean area (115 μm²) were found on the head. We found that 100 random measurements may be sufficient to distinguish differences >7 μm² in mean mucous cell areas. The results further suggest that salmon exhibit a dynamic repeatable pattern of mucous cell development influenced by sex, diet and possibly strain and season.     

Effects of formalin treatment on epithelial structure and mucous cell densities in rainbow trout, Oncorhynchus mykiss (Walbaum), skin

Formalin bath treatments of rainbow trout are widely used for control of ectoparasitic infections in fish farms and the effects of this chemical on parasite infections have been studied. In addition, tolerance of the host to various concentrations of formalin are also known. However, effects of formaldehyde on the skin epithelium integrity and mucous cell density still need elucidation. The present study revealed that exposure of rainbow trout fry 2 months post-hatching to various concentrations of formalin affected the mucous cell dynamics of the fish. Limited exposure (50 ppm, 1 h) stimulated mucous cell proliferation as indicated by the slight increase in densities of Alcian blue positive cells in tail fin epidermis. In contrast, high concentrations (200-300 ppm, 1 h) or lengthy exposure (24 h) at lower concentrations caused a decrease in mucous cell density. Scanning electron microscopy revealed effects on the epithelial structure of fish fins. Blebbing of epithelial cell membranes was the first sign of injury. The dilated openings of mucous cells indicated increased release of mucus. Highly irregular organization of the cells followed, with regional differences occurring in different parts of fins. The implications of formalin bathing for susceptibility or resistance of fish to subsequent pathogen exposure are discussed.     

Food deprivation causes rapid changes in the abundance and glucidic composition of the cutaneous mucous cells of Atlantic salmon Salmo salar L.

Cutaneous mucus is the first physical and chemical barrier of fish. This slime layer is secreted by mucous cells located in the epidermis and is mainly composed of glycoproteins that have their origin in the diet. Therefore, food deprivation can potentially change the abundance and glucidic nature of skin mucous cells, thus changing the mucus properties. To test this hypothesis, we conducted an experiment with Atlantic salmon, Salmo salar L. Changes in the number and glucidic nature of epidermal mucus cells were analysed using standard techniques. The outcome of this study shows that food deprivation caused a rapid decrease in the density of epidermal mucous cells in Atlantic salmon. Lectin histochemistry revealed a change in the presence and stainability of some sugar residues in the mucous cells of unfed fish compared with fed fish. Given that the primary reason for mucus secretion in fish is for protection against infections, we speculate that the changes in the mucus properties caused by nutritional stress may affect their disease resistance. This fact is particularly important for fish that spend a period of time deprived of food, either as a part of their natural life cycle, or as part of farming practices.     

The Irish sea trout enhancement programme: a review of the broodstock and ova production programmes

The Irish sea trout, Salmo trutta L., broodstock programme was instigated in response to the collapse of sea trout stocks in the west coast of Ireland in 1989 and 1990. Wild sea trout kelts and post-smolts were successfully reconditioned and used as broodstock to produce eyed ova for distribution to affected fisheries. From 1991 to 1999, a total of 8.2 million green ova from four separate stocks were produced. The number of females stripped increased from 34 in 1991 to a peak of 1435 in 1997. Green ova survival to the eyed ova stage ranged from 65 to 96%. The eyed ova produced were distributed to 23 affected fisheries along the west coast. The average cost per eyed ova decreased from €2.02 at the start of the programme to €0.04 at the end. The growth rates recorded for broodstock held in captivity were comparable with those recorded for wild sea trout. Relationships between fish size, egg size and number of eggs produced were examined for each stock and for each stock in each year. Significant positive relationships were found between fish size and egg number and fish size and egg size, with the exception of the first year in which fish were stripped, when a negative correlation between fish size and egg size was found.     

Histochemical and immunohistochemical characterization of rodlet cells in the intestine of two teleosts,Anguilla anguilla and Cyprinus carpio

Rodlet cells (RC) are characterized by a distinctive cell cortex and conspicuous inclusions named “rodlets.” These cells are particularly abundant and large in size in intestine of eels. Histochemical, immunohistochemical and ultrastructural investigations were carried out on European eel Anguilla anguilla and Common carp Cyprinus carpio from Northern Italy. Eight biotinylated lectins were used to probe for specific carbohydrate residues in deparaffinized, hydrated intestinal sections of eel and carp. Five antibodies were tested on intestinal sections of both fish species: inducible nitric oxide synthase (i‐NOS), leu‐enkephalin, lysozyme, serotonin and tumour necrosis factor‐α. Lectin histochemistry revealed rodlet cells (RCs) of the eel intestine to react with two of the eight lectins tested, specifically Concanavalin A (ConA) and Sambucus Nigra Agglutinin (SNA). This contrasted to lectin staining of RCs in the intestine of common carp, where four of the eight lectins showed a positive reaction; Dolichos Biflorus Agglutinin (DBA), Wheat Germ Agglutinin (WGA), SNA and ConA. RCs in eel and carp intestine were immunoreactive with antibodies to lysozyme and i‐NOS. The occurrence of the inflammatory peptides lysozyme and i‐NOS in RCs of the eel and common carp poses in favour that these cells are involved in the mechanism of defence against pathogens.     

The residence time of stocked hatchery-reared brown trout, Salmo trutta L., and rainbow trout, Oncorhynchus mykiss (Walbaum), in Lake Trawsfynydd, and their accumulation of radioactive caesium

Abstract Small amounts of radioactivity in liquid effluent are discharged under authorization into Lake Trawsfynydd in north Wales. MAFF inspectors from the Directorate of Fisheries Research (DFR) advise the Welsh Office on the terms of authorization and on the power station operators' compliance with them. DFR also has the responsibility for environmental monitoring, including fish caught for consumption. Trout angling is particularly popular in Lake Trawsfynydd, and because of angling pressure, additional brown trout, Salmo trutta L., and rainbow trout, Oncorhynchus mykiss (Walbaum), need to be introduced. An important factor in determining the concentration of radionuclides in these fish is the length of time that they spend at liberty. During the fishing season, samples of these stocked trout were tagged and released to assess the average residence time. This was found to be 6 days for rainbow trout and 10 days for brown trout. Less than 7% of the recaptured stocked trout of either species had a residence time of more than 20 days. Radiocaesium concentrations in recaptured trout were very low. Trout which avoided recapture and overwintered in the lake were found to have radiocaesium concentrations similar to those of indigenous trout sampled at the same time.     

Recruitment of the threatened mussel Margaritifera margaritifera in relation to mussel population size,mussel density and host density

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The age structure and distribution of Atlantic salmon parr, Salmo salar L., in small tributaries and main stems of the subarctic River Teno, northern Finland

Parr of the Atlantic salmon in subarctic River Teno, northern Finland (70°N, 28°E), are found to migrate to small tributaries that are not spawning areas for the adult salmon. The age distribution of the salmon differs significantly between these brooks and the natal rivers, the parr in the brooks being typically 2–4 years old, whereas those in the main rivers were mostly of age 0–2 years. The older fish were found in the uppermost regions of the brooks. The ratio of salmon to brown trout decreases towards the upper reaches of the brooks. At least some of the young salmon overwinter in the brooks. However, the number of fish and the area inhabited diminished towards the autumn in some occasions. It is suggested that this migratory behavior may be an adaptational phenomenon that could cause variation in survival among young salmon in the River Teno.     

Effects of total fish oil replacement to vegetable oils at two dietary lipid levels on the growth,body composition,haemato‐immunological and serum biochemical parameters in caspian brown trout (Salmo trutta caspius Kessler, 1877)

This research aimed to evaluate the effects of two dietary fat levels [low fat (LF) (10%), high fat (HF) (20%)] and sources [fish oil (FO), vegetable oil (VO)] on the growth and some physiological parameters of Caspian brown trout fingerlings for 60 days. Tuna oil or blends of canola and soybean oils (85:15) were added to diets to design four feeds namely LFFO, HFFO, LFVO and HFVO according to the fat levels and sources. The fish fed the LFFO diet had lower weight gain than the other fish (P<0.05). The total n‐6 fatty acids increased in fish fed diets with the blends of VO, while the total n‐3 fatty acids decreased in these fish (P<0.05). Serum lysozyme activity was higher in fish fed the HFVO diet than the other fish (P<0.05). Serum glucose, total cholesterol, triglyceride and very low‐density lipoprotein were lower in fish fed LFFO than the other fish (P<0.05). The present study demonstrates that in terms of fish growth, VOs can be used as an alternate source of dietary fat, whereas fish health and nutritional value are improved with the LFFO diet. According to these results, a partial substitution of FO by VO in high‐level fat diets is suggested for long‐term feeding of Caspian brown trout.     

The prevalence of escaped farmed salmon, Salmo salar L., in the River Ewe, western Scotland, with notes on their ages, weights and spawning distribution

Abstract  The prevalence of escaped farmed Atlantic salmon, Salmo salar L., in the River Ewe, western Scotland, was assessed. After the establishment of smolt cages in the catchment and marine cages near the river mouth during 1986–1987, approximately 425 000 parr and smolts, and 122 000 growers have escaped. Between 1987 and 2001, farmed salmon occurred in the rod fishery in 13 of the 15 years, contributing at least 5.8% of the total catch, with a maximum annual frequency of 27.1%. It was estimated that <1% of fish escaping from the marine cages entered the river, but contributed at least 27% of potential anadromous spawners in 1997. Radiotagged, farmed fish in 2001 probably spawned in three subcatchments also used by tagged wild fish. Despite the likelihood of hybridisation there was no change in the median weight or marine age of wild fish, but smolt age decreased significantly ( P  < 0.02). The Ewe has a depleted wild salmon population (≤900 anadromous adults), and further genetic introgression by escapees should be prevented.     

高温胁迫下刺参肠道细胞应激颗粒标记蛋白TIA-1的表达特征

产生应激颗粒是生物体遭受不利环境时细胞产生的一种自我保护机制,基于此,本研究开展了高温胁迫下刺参(Apostichopus japonicus)肠道细胞中应激颗粒(Stress granule)标记蛋白基因TIA-1表达特征的研究。采用RACE技术克隆了刺参T细胞胞内抗原-1基因(TIA-1)全长c DNA序列。该基因c DNA全长为3108 bp,包括16 bp的5'UTR,1284 bp的开放阅读框(ORF),1808 bp的3'UTR,编码427个氨基酸。结构分析表明,刺参TIA-1基因编码3个N末端RNA识别基序(RRM)和2个类似蛋白聚集区的C末端区域(low complexity)。系统进化树分析表明,刺参TIA-1与软体动物门鸭嘴海豆芽(Lingula anatina)TIAR聚为一支,具有最近的亲缘关系。使用Western blotting技术检测目的蛋白TIA-1在全细胞和亚细胞成分中的表达差异,并且利用细胞免疫荧光技术检测细胞在高温胁迫下TIA-1的定位情况。研究结果表明,刺参肠道细胞TIA-1在高温胁迫下在细胞质中表达量显著上升(P0.05),且高温胁迫下TIA-1定位表达发生变化,多分布在细胞核周围,由此推断TIA-1在刺参高温应激时可能参与了应激颗粒的生成,从而对刺参肠道细胞起到了保护作用。     

Dietary synbiotics improved the growth,feed utilization and intestinal structure of largemouth bass (Micropterus salmoides) juvenile

This study investigated the effect of dietary synbiotics on the growth, feed utilization and intestinal histology of largemouth bass (Micropterus salmoides). A commercial synbiotic product containing dried powder of yeast, Bacillus subtilis and mannan oligosaccharides was supplemented in basal diet with 0 g/kg (control), 1.0, 2.0, 4.0 and 6.0 g/kg, respectively, and then, the five diets were fed to largemouth bass with body weight of 4.5 ± 0.1 g for 8 weeks. The results showed that the supplementation of 2.0, 4.0 and 6.0 g/kg synbiotics increased weight gain by 20.6%, 17.7% and 11.8% (p < .05) and decreased feed conversion ratio by 0.20, 0.18 and 0.12 (p < .05), respectively, when compared to the control. The protein retention, lipid retention, apparent digestibility coefficient of dry matter and crude protein, and the intestinal villus height and width of 2.0 and 4.0 g/kg synbiotic groups were significantly higher than those of the control (p < .05). The intestinal protease activity and serum lysozyme activity were increased by the addition of 2.0 and 4.0 g/kg synbiotics (p < .05). In conclusion, dietary synbiotics improved the growth, feed utilization and intestinal structure of juvenile largemouth bass, and the recommended inclusion level was 2.0–4.0 g/kg.     

The interaction between temperature and dose on the efficacy and biochemical response of Atlantic salmon to hydrogen peroxide treatment for amoebic gill disease

Hydrogen peroxide (H₂O₂) is a commonly used treatment for a range of parasitic diseases of marine finfish, including amoebic gill disease (AGD). While this treatment is partially effective at reducing parasite load, H₂O₂ can have detrimental effects on the host under certain conditions. Treatment temperature and dose concentration are two factors that are known to influence the toxicity of H₂O₂; however, their impact on the outcome of AGD treatment remains unclear. Here, we investigated the effects of treatment temperature (8, 12 or 16°C) and dose concentration (750, 1,000, 1,250 mg/L) on the efficacy of H₂O₂ to treat AGD. We demonstrated that a 20-min bath treatment of H₂O₂ at all doses reduced both parasite load and gross gill score significantly. Parasite load and gross gill score were lowest in the 1,000 mg/L treatment performed at 12°C. At the high dose and temperature combinations, H₂O₂ caused moderate gill damage and a significant increase in the plasma concentration of electrolytes (sodium, chloride and potassium). Taken together, our study demonstrates that higher H₂O₂ treatment temperatures can adversely affect the host and do not improve the effectiveness of the treatment.