大鲵病毒性疾病最新研究进展

中国大鲵(Andrias davidianus)是我国的特有物种,具有极高的产业开发价值,但病毒性疾病严重危害大鲵人工养殖产业的健康发展。本文对大鲵虹彩病毒的分类地位及主要特征、大鲵虹彩病毒病的病理症状及诊断防治措施几个方面进行了简要概述,以期为大鲵病毒性疾病的深入研究提供科学依据。     

中国大鲵雌雄分类分级高效养殖新模式

中国大鲵(Andrias davianus)俗称娃娃鱼,属两栖类,是著名的活化石,被列为国家二级保护动物,具有很高的科研、食用、药用和观赏价值.大鲵人工繁殖早在70年代取得成功,在人工养殖上存在养殖周期长的特点,要想提高其养殖速度,则要按照其特定的生物学特性来采取各种有效的技术措施.近年来,湖南湘西州利用大鲵原生态区自流水体,进行雌性和雄性大鲵分池分级饲养.中国大鲵雌雄分类分级养殖模式的优点:大鲵群养有相互撕咬的现象,常常造成大鲵受伤,影响其摄食和生长,严重时造成大鲵死亡,影响成活率.分养则可以解决相互撕咬的问题,摄食均匀,促进大鲵生长,同时管理方便,能够大大降低大鲵养殖的成本,降低疾病发生率,促进其快速生长,显著提高经济效益,值得推广.     

中国大鲵人工养殖技术研究进展

大鲵(Andrias davidianus)是中国特有的大型濒危两栖动物,在食用和药用等方面具有重要价值,但因环境污染及过度捕捞,野生大鲵几近灭绝,其人工养殖技术亟待完善。目前大鲵仿生态与工厂化繁殖和养殖技术日渐成熟,饲料与疾病研究逐步深入,但仍存在人工配合饲料研发尚未成功,虹彩病毒病无法有效防治等瓶颈问题。为进一步完善大鲵人工养殖技术,降低养殖成本,提高大鲵品质、养殖成活率,文章从大鲵繁殖技术、苗种培育技术、养殖模式、疾病防治和饲料研发等方面综述其人工养殖技术研究现状,以期为大鲵人工养殖标准化和规模化提供科学参考。     

大鲵腹水病的治疗

中国大鲵（Andria davidianus blanchard）,俗称娃娃鱼,属两栖纲,有尾目,隐鳃鲵科,是一古老的物种,有＂活化石＂之誉,具有很高的经济、科研价值。由于大鲵价值较高,对于其各方面研究较少,特别是一些疾病的研究。近日,当地爆发大鲵疾病,死亡率很高,对病鲵的治疗发现,有部分属腹水病范畴。在此,特针对治疗腹水病过程中的一些收获作简要介绍。     

大鲵水霉、肠炎、烂尾『三病』综合防治技术

大鲵(Andriasdavianus),俗称娃娃鱼,属两栖纲、有尾目、隐鳃鲵科,为我国特有的大型两栖动物,具有很高的食用、科研及药用价值。近年来,大鲵作为一种新开发的名贵水产动物,越来越多的单位和个人从事大鲵的人工养殖,但人工养殖的大鲵由于技术不到位常患各种疾病,造成较大的损失。     

浅谈大鲵病害发生原因及诊断给药方法

随着大鲵养殖业的兴起,越来越多的病害也伴随而来,成为大鲵产业发展的最大瓶颈。本文从技术员的角度通过分析引起大鲵疾病的原因以及病原的传播途径,总结了大鲵疾病有效的、简易的诊断方法以及常用的给药方式,以其为大鲵养殖户提供参考,促进大鲵养殖业健康发展。     

浅析快速提高大鲵生长速度的要点

大鲵（Andrias davidianus）俗称娃娃鱼,属于脊椎动物门,两栖纲,有尾目,隐鳃鲵科,为我国特有的珍稀两栖动物,又称中国大鲵。它是世界上最大的两栖动物和濒危的国家二级保护动物。主要生活在我国华南和西南的山涧溪流中,其中尤以湖南,湖北,四川,陕西,河南等省区较多见,由于大鲵肉质细嫩,味道鲜美,药用价值高,具有极大的经济效益和社会效益,吸引越来越多的养殖者开展大鲵人工养殖。笔者自1999年以来一直从事大鲵的人工繁殖与养殖方面的研究,在人工养殖模式下,通过多年的摸索,突破了自然界中野生大鲵生长速度缓慢的缺陷,使得大鲵的生长速度获得了显著的提高,现将有关经验总结如下。     

大鲵（娃娃鱼）的五种增殖技术模式

大鲵是中国的特有物种,生长快、个体大,且资源分布广达17个省、市,除中国大鲵以外,世界上只有美国隐鳃鲵和日本山椒鲵的零星分布。美国隐鳃鲵分布在美国东部,由于河流淤积、筑坝成湖、捕杀与过度采集、水污染等原因,其资源已经濒临灭绝的危险。因此就资源而言,中国大鲵处于绝对优势。它还是当今世界上剩存的从水生演变成陆生动物,最具典型的过渡性动物,具有“活化石”之称。新近调查发现,大鲵还出现了“白玉色”、“红色”与“金黄色”的珍美绝品大鲵,所以中国大鲵是世界上神奇而美丽的观赏动物,     

娃娃鱼养殖技术

<正>娃娃鱼学名大鲵,属大型两栖类珍稀动物。全世界现存大鲵仅3种,除中国大鲵之外,还有日本大鲵、美国隐鳃大鲵。我国大鲵主要产于长江、黄河及珠江中、下游支流的山溪中,遍及山西、陕西、湖南、湖北、安徽、四川、贵州、广东、广西等地。娃娃鱼在食用、药用、观赏、科研等方面具有极其重要的价值。由于不法分子大量非法捕捉贩卖和天然生态环境的破坏使得大鲵野生资源锐减。近年来,随着大鲵人工繁育技术的攻克,大鲵人工养殖成为可能。同时,为支持大鲵人工     

大鲵感染虹彩病毒的诊断和治疗

2013年7月,陕西省汉中某大鲵养殖场发生以大鲵体表和四肢多处溃烂并伴有出血为特征的疾病,染病大鲵大量死亡。经临床观察、病理解剖及实验室检测,最后确诊病原为大鲵虹彩病毒。通过采取综合防治措施,养殖场大鲵疫情得到有效控制。     

Rare serotype occurrence and PFGE genotypic diversity of Streptococcus agalactiae isolated from tilapia in China

Previously, we reported 10 PEGE types of 85 tilapia Streptococcus agalactiae(GBS), which shifted from Streptococcus iniae in China, by using PEGE method. Presently, larger and more representative tilapia GBS were isolated, for the ?rst time in China, to characterize their serotypes and genetic diversities more precisely than had done before. 168 GBS strains were distributed in ?ve provinces of China, in which Guangdong, Guangxi and Hainan were the major ones, holding36.9%(62/168), 37.5%(63/168) and 19.6%(33/168), respectively. Serotypes, Ia, Ib and III, were observed in these strains and the most predominant one was Ia(95.2%), which mainly distributed in Guangdong, Guangxi and Hainan. Ia initially occurred in 2009, it shoot up to 32.1% in 2010,but decreased to 16.1% in 2011 before went up to 45.2% in 2012. Ib sporadically occurred during2007–2011, III onlyoccurred in 2012. 14 different PFGE types, including 4 new types(N, O,P and Q), were observed, in which B, D, F and G were the predominant types, holding 83.9%(141/168) of the total GBS strains. Ia corresponded to 11 PFGE types(A–H, N–P), in which type D predominated(51%). Ib represented 3 genotypes(I, J and Q) and III harbored only 2genotypes(N and F). Type N and Fsynchronously presented in Ia and III. In summary, the genetic diversity of tilapia GBS varied by serotypes and changed with geographical locations and years.Although Iastillpredominated, new rareserotypeIII alreadyoccurred in China.     

Growth hormone (GH) and reproduction: a review

Interaction between growth and reproduction occurs in many vertebrates and is particularly obvious at certain stages of the life cycle in fish. Endocrine interactions between the gonadotropic axis and the somatotropic axis are described, the potential role of GH being emphasised. A comparative analysis of these phenomena in mammals, amphibians and fish, suggests a specific role of GH in the physiology of puberty, gametogenesis and fertility. It also shows the original contribution made by studies on the fish model in this field of investigations.     

Purification and partial characterization of GtHs (cfLH and cfFSH) from Indian walking catfish (Clarias batrachus) (L.) and development of a homologous ELISA for cfLH

Two gonadotropins (GtH; Qa and Qb) were purified by gel filtration and ion exchange chromatography from the pituitaries of Indian walking catfish (Clarias batrachus). The presence of GtH during purification was assessed by in vitro oocyte maturation and in vivo steroidogenic activity, and their identities were determined by elution profiles, molecular weight, biological activities and yield. The molecular weights of Qa and Qb were 37 and 42 kDa, respectively, and composed of distinct subunits (Qa: 20 and 14 kDa and Qb: 26 and 18 kDa). Polyclonal antibodies raised against Qa immunostained Qa, Qb and pituitary GtH cells. A competitive Qa‐ELISA was developed whose sensitivity was 6.25 ng mL^?1 (1.25 ng well^?1) with intra‐ (3.5%) and inter‐ (12.4%) assay coefficients of variation. Displacement curves parallel to the standard were obtained with plasma and pituitary extracts of catfish, Qb and carp GtHII. The assay was validated by measuring the plasma Qa levels after LHRH treatment and in relation to ovarian growth in the female catfish during different reproductive phases. Based on the results, Qa and Qb corresponded to fish LH and FSH respectively. The findings will increase the knowledge of the mechanisms controlling fish reproduction and identification of sensitive phases in fish in captivity for hormonal manipulation.     

Controlled infection of Poecilia reticulata Peters (guppy) with Tetrahymena by immersion and intraperitoneal injection

Tetrahymena is a protozoan parasite, which infects guppy, Poecilia reticulata Peters, and causes substantial economical losses in commercial farms worldwide. Studies of guppy infected by Tetrahymena require standardized infection protocols. The LD50 for Tetrahymena infection of guppies by intraperitoneal (IP) injection was calibrated, and the level obtained was 946 parasites per fish. Guppy infection with Tetrahymena by immersion, imitating the natural route of infection via the integument, was studied under normal or stress conditions. Exposure to cold and netting (CNI) and to cold only (CI) followed by immersion exposure to 10 000 Tetrahymena per mL resulted in 22.5% and 19.2% mortality, respectively, as compared to 14.2% and 10% in groups that were netted only (NI) or non‐stressed (I). Histopathology revealed that immersion infection resulted in a systemic infection. Lysozyme levels, measured 3 weeks after infection, were significantly higher in the CNI group (288 μg per mg protein) compared with CI‐, NI‐ and I‐treated groups (94.5, 64 and 62.3 μg mg^?1, respectively). There was no evident parasite immobilization activity in body homogenates, suggesting no development of acquired immunity. Re‐infection by IP injection revealed no increase in protection in any of the treatment groups, mortality range of 56.3–75%, higher than in the non‐exposed control (40.6% mortality).     

Imported ornamental fish are colonized with antibiotic‐resistant bacteria

There has been growing concern about the overuse of antibiotics in the ornamental fish industry and its possible effect on the increasing drug resistance in both commensal and pathogenic organisms in these fish. The aim of this study was to carry out an assessment of the diversity of bacteria, including pathogens, in ornamental fish species imported into North America and to assess their antibiotic resistance. Kidney samples were collected from 32 freshwater ornamental fish of various species, which arrived to an importing facility in Portland, Oregon from Colombia, Singapore and Florida. Sixty‐four unique bacterial colonies were isolated and identified by PCR using bacterial 16S primers and DNA sequencing. Multiple isolates were identified as bacteria with potential to cause disease in both fish and humans. The antibiotic resistance profile of each isolate was performed for nine different antibiotics. Among them, cefotaxime (16% resistance among isolates) was the antibiotic associated with more activity, while the least active was tetracycline (77% resistant). Knowing information about the diversity of bacteria in imported ornamental fish, as well as the resistance profiles for the bacteria will be useful in more effectively treating clinical infected fish, and also potential zoonoses in the future.     

Effect of iodophor disinfection of non‐hardened Salmo trutta eggs on their bacterial and fungus load

This study investigated the efficiency of iodophor disinfection (135 ppm active iodine for 15–30 min) of non‐hardened Salmo trutta eggs against different groups of bacteria and against fungus. Egg samples were taken from non‐disinfected and from disinfected eggs, microorganisms were cultured on specific nutrient media and their mass was measured by turbidimetric methods. Bacteria and fungus mass of non‐hardened eggs could be reduced but not eliminated by iodophor disinfection with 135 ppm active iodine for 15 min. The extent of reduction was 47–65% (Experiment 1). The efficiency of disinfection increased with disinfection time as the reduction in bacteria and fungus mass was 40–55% after 15 min and 58–74% after 30 min (Experiment 2). Disinfection efficiency of iodophor solution diluted in water (reduction 49–57%) and of iodophor solution diluted in sodium chloride solution iso‐osmolar to the oocytes (reduction 52–61%) was similar (Experiment 3). The reduction in bacteria and fungus mass was persistent as it was 39–72% lower in embryos deriving from disinfected eggs than in embryos deriving from non‐disinfected ones (Experiment 4). In conclusion, the tested disinfection method is inadequate to eliminate pathogens completely but it could positively influence immune defence of eggs and embryos.     

Nitrogenous waste excretion and accumulation of urea and ammonia inChalcalburnus tarichi (Cyprinidae), endemic to the extremely alkaline Lake Van (Eastern Turkey)

The endemic, anadromous cyprinidChalcalburnus tarichi is the only fish species known to occur in alkaline Lake Van (Eastern Anatolia, Turkey). EightC. tarichi were maintained individually in Lake Van water (17 – 19°C; pH 9.8; 153 mEq·I^–1 total alkalinity; 22 total salinity) and tank water samples analyzed for 24 h in 2 to 4 h intervals. At zero time, < 1µM ammonia was present and urea was undetectable in the tank water; at 24 h, total ammonia and urea made up 114±32 and 35±25µM, respectively. Over the experimental period, ammonia-N and urea-N excretion averaged 1041±494 and 607±169moles·kg^–1 fish·h^–1, respectively. The extent of urea excretion was highly variable between specimens. Uric acid excretion was not detectable.Urea was present at high concentrations in all tissues and plasma (25 – 35moles·g^–1·ml^–1) of freshly caughtC. tarichi; total ammonia content of the tissues was by a factor of 1.9 (liver) to 3.0 (brain) lower. High arginase activity (2.4±0.2 U·min^–1·g^–1) was detected in the liver ofC. tarichi but ornithine carbamoylphosphate transferase, a key enzyme of the ornithine-urea-cycle, was absent. Ureagenesis is likely through degradation of arginine and/or uricolysis. High glutamine synthetase activity (11±0.6 U·min^–1·g^–1) and low ammonia content in brain suggest that, like other teleosts,C. tarichi has an efficient ammonia detoxification in the brain, but in no other tissue.Nitrogenous waste excretion at alkaline pH is discussed. The ability ofC. tarichi to excrete high levels of ammonia at extremely alkaline pH is unique among teleosts studied so far. The mechanism of ammonia excretion under Lake Van conditions remains to be elucidated.     

Influence of the antibacterial herbs, Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia on the survival, growth and bacterial load of Penaeus monodon post larvae

The indiscriminate use of antibiotics and chemicals in shrimp hatcheries has led to biomagnification and that in turn could lead to rejection of a whole consignment. The application of the bioencapsulation technique as a tool for curative treatment in shrimp larvae was investigated. Herbs having antibacterial properties such as Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia (methanolic extracts) were bioencapsulated in Artemia and fed to Penaeus monodon post larvae PL 1–25. The post larvae were reared in a medium inoculated with pathogenic bacteria such as Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella typhi and Vibrio sp. Post larvae reared in the non-inoculated water and fed with non-enriched Artemia exhibited 90% survival, highest specific growth rate (12.43%) and reduced bacterial load. P. monodon reared in the bacterial inoculated water and fed with the non-enriched Artemia exhibited the lowest survival (10–30%), specific growth rate (8.42–9.1%) and increased bacterial load (2.86 × 10³ to 3.76 × 10⁵ cfu/g). The methanolic extracts of the herbs helped to increase survival and specific growth rate and reduced bacterial load in the P. monodon culture system. Among the three herbal extracts, P. corylifolia enriched Artemia fed post larvae showed the tendency to higher survival (>50%), growth rate (11.5 averaged) and low bacterial load (1.12 × 10⁵ cfu/g). This revised version was published online in August 2006 with corrections to the Cover Date.