罗源湾网箱养殖鱼类寄生虫病流行病学调查与分析

2005-2010年从罗源湾网箱养殖鱼类中检出10种主要寄生虫,其中刺激隐核虫和本尼登虫是罗源湾网箱养殖鱼类危害最大的两种寄生虫,大黄鱼是受寄生虫危害最严重的鱼类。寄生虫在时间分布上与水温的变化密切相关,在空间分布上取决于宿主、养殖密度、水流和水质。     

辽宁西部海域主要食用鱼类寄生虫感染情况初报

采用鱼类全身性寄生虫学检查法,在辽宁西部海域随机抽检主要食用鱼类19种共计769尾,其中养殖鱼类4种202尾、野生鱼类15种567尾,发现该海域19种食用鱼类感染体内外寄生虫15种,分别隶属于6纲12科15属。在统计感染率和感染强度的基础上,确定优势虫种为异尖线虫科的3属幼虫:宫脂线虫属幼虫、对盲囊线虫属幼虫、异尖线虫属幼虫,野生和养殖鱼类均有较高的感染率,而针对4种养殖鱼类而言,尤其是牙鲆和大菱鲆,其优势虫种为指状拟舟虫和刺激隐核虫,在各个鱼类养殖场中均有较高的感染率和发病率。     

沙棘果对高脂膳食大鼠肝脏脂代谢的影响

为了研究沙棘果对高脂膳食大鼠肝脏脂代谢的影响,以60只雄性Wistar大鼠为研究对象,随机分为5组,对照组、高脂模型组、沙棘果低、中和高剂量组。对照组给予基础饲料,其余各组给予高脂饲料喂养,同时试验组每日用不同浓度的沙棘果匀浆液灌胃大鼠。4周后处死动物,采集肝脏,分别测定肝脏脂质、脂代谢相关酶及抗氧化指标,光镜下观察肝脏组织病理改变。结果:沙棘果匀浆液可显著降低肝脏总胆固醇(TC)水平,增加高密度脂蛋白(HDL-C)水平;使肝脏组织总脂酶(LPS)、肝脂酶(HL)和脂蛋白脂酶(LPL)活性增强,MDA生成量减少。结论:沙棘果可降低高脂膳食大鼠肝脏脂质水平,提高肝脏脂代谢酶活性,增强抗氧化能力,减缓肝细胞的脂质过氧化。     

加州鲈商品鱼池塘养殖技术

加州鲈属广温肉食性淡水名贵鱼类，具有适应广、生长快、病害少、易起捕，肉味美、营养价值高，市场前景好等特点，是发展池塘高效养殖的重要经济鱼类之一。同时，因该鱼较贪食，易上钩，又是发展游钓渔业的好品种。为此，本文简要介绍加州鲈商品鱼池塘养殖和常见病防治技术。     

刺激隐核虫病害情况分析与防控措施探讨

<正>刺激隐核虫(Cryptocaryon irritans Brown),又称海水小瓜虫(Ichthyophthirius marinus),属原生动物门、纤毛亚门、寡膜纤毛纲、膜口亚纲、膜口目、凹口科、隐核虫属。刺激隐核虫无特定宿主,几乎危害所有海水养殖鱼类,包括大黄鱼、大菱鲆、黑鲷、红笛鲷、石斑鱼、卵形鲳等。近几年来,在福建、浙江、广东等主要海水鱼类     

胡子鲶网箱养殖试验

胡子鲶俗称塘鱼，属胡子鲶科．胡子鲶属。广东省本地种称本地塘，原系野生鱼类，栖息于河川下游和田野坑渠、池塘的石缝暗沟处，喜群居。塘鱼贪食，以摄食动物性饵料为主，属底栖腐屑食性的杂食鱼类。其肉味鲜美、营养丰富，市场价格较高。成为人们竞相研究开发的养殖对象。目前，本地塘鱼的养殖仅限于池塘单养或套养，成活率较低，生长速度慢，难起捕。用网箱养殖本地塘鱼尚无成功的技术报道。我公司网箱养殖试验场在今年六至九月间，用网箱成功地养殖本地塘鱼1500余尾，四百多斤。现将我场的试验情况介绍如下。1．材料和方法1．1材料使用…     

中西药结合治疗鲤鱼粘孢子虫病

孢子虫是寄生在淡水鱼类的原生动物中种类最多,分布最广的一类寄生虫。在我国淡水鱼类中寄生的孢子虫,已知道的种类按分类系统包括四大类,即球虫、粘孢子虫、微孢子虫和单孢子虫,其中以球虫和粘孢子虫对鱼的危害最大。 黄壁庄水库网箱养殖中出现了两种孢子虫,一种是粘孢子虫中的鲮单极虫,另一种是微孢子虫中的赫氏格留虫(主要感染体表,没发现引起鱼体死亡),前一种在几年的网箱养殖中危     

鱼类养殖营养研究的成果与动向 日本第289次月例研究会资料

日本对鱼类养殖的营养研究已有数十年历史。起初研究的对象主要是鲤、鳗、钻等淡水鱼类;其内容主要是蛋白质、脂肪、碳水化合物、维生素和矿物质等,目的在于防止鱼类发生残疾。随着研究的进步,不仅明晰了多种鱼病的发生机理,范围也扩大到罗非鱼、鰤、对虾(甲壳类)和海产鱼贝类,获得了很多有价值的成果。近年来随着鱼类养殖技术的国际交流,     

淡水鱼春季常见疾病与防治

本文详细介绍春季在淡水鱼类养殖过程中常见的鱼类疾病,主要分为微生物性鱼病,如赤皮病、竖鳞病、水霉病;寄生虫性鱼病,如小瓜虫病、车轮虫病、斜管虫病、鲺病、蛭病、钩介幼虫病;以及气泡病、萎瘪病等其他鱼病。重视春季鱼病的防治工作,调节水质,保护水环境。     

几种养殖鱼类血清转氨酶活性参考值的探讨

探讨鱼类血清中丙氨酸转氨酶(ALT)和天门冬氨酸转氨酶(AST)活性的评价标准。试验选取了不同地区(江苏、浙江、河北、天津、广东、湖北)的几种主要养殖鱼类,针对其ALT、AST活性进行了检测,同时结合其生长状况、肝(胰)脏脂肪含量及肝(胰)脏组织冰冻切片状况等,进行了初步的探索,以期为养殖鱼类转氨酶评价标准的建立及鱼类健康养殖和调控技术提供一定的基础数据,具有一定的现实参考意义。     

Effect of the type of extraction solution and length of storage on the distribution of lactate dehydrogenase isoenzymes in piglet liver homogenate

Type of extraction solution applied to preparation of homogenate of piglet liver is of negligible importance, if immediately follows electrophoretic separation of tissue material. --Storage of liver homogenates in frozen state over 30 days involves insignificant changes of distribution of LD isoenzymes in 0.25 M sucrose, distinct changes in 0.1 M Tris-buffer, pH 7,5, and important ones in mercaptoaethanol-containing extraction solution, applied to preparation of tissue homogenates.     

Thiaminase Activity of Crucian Carp Carassius carassius Injected with a Bacterial Fish Pathogen,Aeromonas salmonicida subsp. salmonicida

Abstract

Dietary thiaminase I is a cause of thiamine deficiency in animals. The physiological significance of thiaminase in the organisms containing this enzyme is not known, nor are the factors causing variation in their thiaminase activity. Tests were performed to evaluate the effect a pathogen might have on thiaminase activity in fish, when analyzed both with a cosubstrate added (CATA tests) and no cosubstrate added (NCATA tests). Pyridine is known as a cosubstrate specific for thiaminase I activity that does not accelerate thiaminase II activity. Crucian carp Carassius carassius known to harbor thiaminase I activity were injected intramuscularly with live Aeromonas salmonicida, a pathogenic bacterium of fish. For comparison, other groups were injected with formalin-killed bacteria and phosphate-buffered saline, respectively; an untreated group of fish was kept as a control. The bacteria did not contain any thiaminase activity. Significantly higher thiaminase activities (CATA and NCATA) were measured in all tissues (whole blood, injected muscle, uninjected muscle, and whole fish homogenates) of fish injected with live bacteria than in the saline-injected and the uninjected groups. The thiaminase activity of blood and that in the injected, inflamed muscle tissue followed different allocation patterns in fish injected with live A. salmonicida. The amount of thiaminase I enzyme appeared to be elevated in the whole blood of injected fish in the absence of natural cosubstrate(s). The thiaminase activity of the injected, inflamed muscle suggested that both the amount of thiaminase enzyme and some yet-unidentified natural cosubstrate(s) were elevated. This suggests that in addition to the enzyme, some cosubstrate(s) of fish or pathogen origin play a regulatory role in the so-far-unknown physiological significance of thiaminase I activity in vivo. It is suggested that the health of fish should be considered when searching for factor(s) affecting its thiaminase activity.     

Development and standardization of a monoclonal antibody-based rapid flow-through immunoassay for the detection of Aphanomyces invadans in the field

A monoclonal antibody-based flow-through immunoassay (FTA) was developed using a nitrocellulose membrane placed on the top of adsorbent pads enclosed in a plastic cassette with a test zone at the center. The FTA could be completed within 10 min. Clear purple dots against a white background indicated the presence of Aphanomyces (A.) invadans. The FTA limit of detection was 7 µg/mL for A. invadans compared to 56 µg/mL for the immunodot. FTA and polymerase chain reaction (PCR) could detect A. invadans in fish tissue homogenates at a 10^-11 dilution compared to a 10^-8 dilution by immunodot. In fish suffering from natural cases of epizootic ulcerative syndrome (EUS) collected from Mangalore, India, FTA and PCR could detect A. invadans in 100% of the samples compared to 89.04% detected by immunodot. FTA reagents were stable and produced expected results for 4 months when stored at 4~8℃. This rapid test could serve as simple and cost-effective on-site screening tool to detect A. invadans in fish from EUS outbreak areas and in ports during the shipment of live or frozen fish.     

Effects of Feeding Spirulina on Specific and Nonspecific Immune Responses of Channel Catfish

Abstract

Administration of various immunostimulants to fish has resulted in enhanced immune responses. The purpose of this study was to determine if feeding Spirulina, a processed form of the blue-green alga Spirulina platensis, enhanced specific and nonspecific immunity and resistance against Edwardsiella ictaluri infection in channel catfish Ictalurus punctatus. Peritoneal phagocytes from fish fed Spirulina showed enhanced phagocytosis to zymosan and increased chemotaxis to E. ictaluri exoantigen. No significant difference in mortality due to E. ictaluri existed between fish fed Spirulina and fish fed a basal diet. No significant difference in antibody titer or in the percentage of fish positive for E. ictaluri antibody was found between the groups after immunization with formalin-killed E. ictaluri. Spirulina-fed fish had significantly higher antibody titers to key hole limpet hemocyanin (KLH) on day 22, and a greater percentage of these fish were positive for KLH antibody on days 15 and 36. Feeding Spirulina enhanced nonspecific cellular immune responses such as chemotaxis and phagocytosis but did not provide protection against infection with E. ictaluri. The use of Spirulina in feed resulted in enhanced antibody responses to KLH, a thymus-dependent antigen, but not to E. ictaluri, a thymus-independent antigen. These results indicate that stimulation of the nonspecific immune system of channel catfish does not provide enhanced protection from E. ictaluri.     

Development of a PCR assay for Streptococcus iniae based on the lactate oxidase (lctO) gene with potential diagnostic value

Streptococcus iniae is a well-known pathogen of both fish and humans that is difficult to identify by conventional biochemical tests. A PCR assay based on the lactate oxidase (lctO) gene of S. iniae was developed for the rapid and specific detection and identification of this pathogen from different sources. The PCR assay had a detection limit of 62-31 cells, and 25 pg of DNA per PCR reaction mixture. The PCR was also effective in detecting the bacterium from inoculated tissue homogenates, suggesting its potential use for a rapid and accurate diagnosis of S. iniae infections.     

Detection of lymphocystis disease virus (LCDV) in asymptomatic cultured gilt-head seabream (Sparus aurata, L.) using an immunoblot technique

An immunoblot technique for the detection of lymphocystis disease virus (LCDV) in naturally infected gilt-head seabream (Sparus aurata, L.) has been developed. A specific antiserum against a 60 kDa viral protein has been proven to be an appropriate tool for LCDV diagnosis either from inoculated cell cultures or from fish tissues using the immunoblot assay. The sensitivity of this technique varied between 10(-1) and 10(2) TCID50. LCDV has also been detected in fish tissues from both, diseased and asymptomatic gilt-head seabream. For the asymptomatic fish detection, a viral amplification step in cell culture and a subsequent viral concentration using polyethylene glycol (PEG) (600 wt) are required. On the contrary, immunoblot allowed the detection of LCDV antigens directly from tissue homogenates of diseased fish. The method described in this study shows higher sensitivity than classical detection techniques based on cell culture inoculation.     

Simultaneous detection and strain differentiation of Mycobacterium bovis directly from bovine tissue specimens by spoligotyping

Culture of Mycobacterium bovis is used routinely to support field diagnosis of bovine tuberculosis; however, this method is slow. Rapid detection and strain-typing of M. bovis directly from 37 lesioned bovine lymph node specimens was performed by the polymerase chain reaction (PCR) based method, spoligotyping. Mycobacterial DNA was extracted from the specimens using a nucleic acid sequence capture technique. Two sets of specimens were tested, the first set comprising 16 decontaminated tissue homogenates from lesioned lymph node specimens which had been processed for BACTEC culture and a second set of 21 non-decontaminated lesioned lymph node specimens. Both sets of specimens had been frozen before analysis. Sequence capture PCR enabled detection and strain-typing of M. bovis directly from 15 of the 16 decontaminated homogenates and all 21 of the non-decontaminated tissues. Four spoligotype (ST) patterns were obtained from each set; ST1, ST2, ST3 and ST16 were detected in the decontaminated specimens and ST1, ST2, ST11 and ST14 in the non-decontaminated specimens. For both sets of specimens, ST1 was the predominant strain type detected. ST patterns obtained from the BACTEC cultures of the decontaminated specimens were in agreement with those obtained directly from the tissue. The sensitivity of detection by sequence capture-PCR compared very favourably with that of BACTEC culture. ST patterns were obtained directly from tissues of 34 of the 35 culture positive specimens and the two culture negative specimens. DNA extraction from the 21 non-decontaminated specimens involved an initial stomaching treatment. An assessment of sequence capture on both liquid alone and liquid and tissue homogenate combined, following stomaching, indicated that PCR was less successful on the liquid component alone.     

Communications: Isolation of Several Mycobacterium Species from Fish

Abstract

Several species of marine fish caught in the wild and of freshwater ornamental fish were used in this study. Infected organs (liver, spleen, and kidney) were sampled for mycobacteria. Decontaminated tissue samples were plated onto selective media for mycobacterial recovery. After initial isolation, fluorescent and acid-fast staining techniques identified bacterial colonies to genus. Profiles of biochemical growth characteristics were used to further identify the isolates to species. Five species of Mycobacterium were identified: M. simiae, M. scrofulaceum, M. marinum, M. chelonae, and M. fortuitum. Of these, M. simiae and M. scrofulaceum have not been previously reported from fish. Tissue samples containing focal granulomatous lesions were prepared for electron microscopic examination.     

Survey on Myxobolus infection of the bleak (Alburnus alburnus L.) in the river Danube and in Lake Balaton

In a three-year survey of myxosporean infections of the bleak (Alburnus alburnus), involving the examination of 205 fish specimens from the River Danube and 50 from Lake Balaton, four Myxobolus species (two gill parasites, one fin parasite and a species parasitising the skeletal muscles) were detected. Two of the species could be identified as M. alburni and M. obesus. Of the other two species, the gill parasite proved to be a hitherto undescribed species which is described here as a new species by the name of M. margitae. One of the two gill-parasitic species, M. obesus, formed plasmodia in the respiratory lamellae of the gill filaments, while the plasmodia of M. margitae n. sp. were formed in the afferent artery of the primary gill filaments. The plasmodia containing spores morphologically identifiable with the species M. alburni were located in the connective tissue between the fin rays. The less frequently found muscle-parasitic Myxobolus species has not been identified precisely. The plasmodia of M. obesus were found in the fish in May and June, while those of M. alburni and M. margitae n. sp. in July and August. The prevalence of infection in fish examined in these periods was 15.5% for M. obesus, 11.5% for M. margitae and 14.0% for M. alburni.     

Detection of early stages of Myxobolus cerebralis in fin clips from rainbow trout (Orynchus mykiss).

A nested polymerase chain reaction (PCR) assay was used to detect early stages of Myxobolus cerebralis in caudal and adipose fin samples from rainbow trout (RT). To determine sensitivity, groups of 10 RT were exposed to 2,000 M. cerebralis triactinomyxons/fish for 1 hour at 15 degrees C and subsequently moved to clean recirculating water. Fish were held for 2 and 6 hours and 1, 2, 3, 5, 7, 10, 30, and 60 days before sampling by nonlethal fin biopsy. Nested PCR performed on fin clips showed that M. cerebralis DNA was detected in caudal fin tissue in 100% of fish up to 5 days postexposure. At days 7 and 10 postexposure, 80% of fish were positive, and at 60 days postexposure, 60% of fish were positive using this technique. Conversely, testing on adipose fin clips proved less sensitive, as positive fish dropped from 80% at day 7 to below 20% at day 10 postinfection. Since detection of M. cerebralis infection using caudal fin samples coupled with nested PCR is an effective method for detection of early parasite stages, use of this technique provides for accurate, nonlethal testing.