牙鲆盾纤毛虫病及防治技术研究

从牙鲆(Paralichthys oliuaceus)患病鱼体的溃烂组织中分离出一种盾纤毛虫,通过活体观察、碳酸银法和电镜观察,对其进行了形态学研究分析。鉴定该盾纤毛虫为贪食迈阿密虫(Miamiensis avidus Thompson & Moewus,1964)。这是国内关于贪食迈阿密纤毛虫感染养殖牙鲆的首次报道。同时本文在防治方法方面进行了初步研究,通过离体药敏实验表明:淡水、甲醛、双氧水对该纤毛虫有较好杀灭作用,而中草药的杀灭效果不理想。     

牙鲆幼鱼盾纤毛虫病药物防治初步试验

牙鲆养殖过程中,经常发现牙鲆体表充血溃烂.引起死亡,给养殖业造成巨大的经济损失。日本Ototake(1986)首次报道养殖牙鲆发生体表溃烂,发现病原主要是盾纤类纤毛虫(Scuticociliatid ciliate)[2]。盾纤毛虫主要寄生于牙鲆和其他海水鱼类的体表皮肤甚至内脏及脑中,引起幼鱼大量死亡[3]。通过对治疗药物的试验,筛选适用于养殖生产治疗盾纤     

防治盾纤毛虫病药物筛选实验

对目前我国牙鲆、大菱鲆养殖过程中普遍发生的一种重要疾病——盾纤毛虫病的防治药物进行了筛选及临床实验。实验表明,甲醛(400 mg/L以上)和硫酸铜(淡水条件下)有较好杀除效果,而淡水浸泡、双氧水、高锰酸钾等则无效。     

海水养殖鱼类盾纤虫病

1　前言自 1 985年在日本三重县、长崎县发现与牙鲆稚鱼盾纤虫病以来 ,作为一种新病 ,盾纤虫病现已广泛见于日本养殖牙鲆、真鲷、红鳍东方鱼屯、六线鱼和韩国一些养殖鱼类。而且 ,近年该病也已成为我国养殖牙鲆、红鳍东方鱼屯、大菱鲆常见寄生虫性疾病。在其它国家 ,循纤虫病也见于大菱鲆和南方蓝鳍金枪鱼 (麦氏金枪鱼 )。2　病原体形态与生态特征病原体属于纤毛虫门 (Ciliophora)少膜纲(Hymenostomatia)盾纤目 (Scuticociliatida) ,种名未定。不过 ,又有研究发现 ,大菱鲆盾纤虫病病原体像是尾丝虫属 (Uronema)盾纤虫。虫体泪珠形 ,全身有…     

寄生于养殖牙鲆体表溃烂组织中的水滴伪康纤虫

从牙鲆(Paralichthys oliuaceus)体表溃烂组织中分离到一种盾纤毛虫,通过活体观察、电镜扫描、蛋白银染色法、银浸法,对其分类学和形态学进行了研究。经鉴定该纤毛虫为水滴伪康纤虫(Pseudocohnilem-bus persalinus Evans&Thompson,1964),隶属于寡膜纲、盾纤目、嗜污科、伪康纤虫属。     

东方红鳍鲀盾纤毛虫病的治疗试验

近几年,我国沿海各个养殖大鲮鲆、牙鲆、河以及甲壳类水生动物的养殖场,都不同程度地受到了盾纤毛虫的危害。山东省乳山市一家养殖场,2003年80万尾东方红鳍在越冬前,因患盾纤毛虫病,全部死亡,经济损失1140万元。山东省文登市一家河越冬场,4万尾规格300￣400克/尾的网箱苗种,于2     

大菱鲆与牙鲆盾纤类纤毛虫病的防治技术

盾纤类纤毛虫病是一种对大菱鲆与牙鲆危害很大的寄生虫性的疾病,2000～2002年山东省文登市的几家养殖场先后发生过此病,引起苗种及商品鱼大量死亡,死亡率高达70%以上,危害很大。现将我们掌握的情况介绍如下。一、病原喙突拟梭虫(Paralembusrostratus)是盾纤类纤毛虫(Scuticociliatidciliate)的一种,为兼性寄生纤毛虫,以细菌和有机碎屑为食,在水中自由生活,亦可侵入寄主体内营寄生生活,虫体为葵花籽状,体被均匀一致的纤毛,大小20～40微米。二、症状患病鱼摄食量减少,在育苗池或养殖池中分布散乱,且常有不安地狂动、狂游。患病的大菱鲆商品鱼…     

大菱鲆与牙鲆盾纤毛虫病的防治技术

盾纤类纤毛虫是一种危害大菱鲆与牙鲆的寄生虫性疾病,2000年~2002年,山东省文登市的几家养殖场先后发生此病,引起苗种及商品鱼的大量死亡,死亡率高达70%以上,危害较大。一、病原喙突拟梭虫(Paralembusrostratus),是盾纤类纤毛虫(Scuticociliatid ciliate)的一种,为兼性寄生纤毛虫,以细菌和有机碎屑为食,在水中自由生活,亦可侵入寄主体内营寄生生活。虫体为葵化籽状,体被均匀一致的纤毛,大小20um~40um。二、症状患病鱼体摄食量减少,在育苗池或养殖池中分布散乱,且常有不安地狂动、狂游。患病的大菱鲆商品鱼体色发黑或发红,眼球突出,鳃盖及吻…     

牙鲆腹水病病原及防治

牙鲆为比目鱼类,在分类上属鲽形目,鲆科,牙鲆属是一种名贵鱼类,其生长迅速,肉质细嫩,味道鲜美,营养价值较高.随着牙鲆鱼高密度工厂化人工养殖的发展,牙鲆疾病日趋严重,已成为制约养殖生产发展的重大障碍,各地养殖场每年都因疾病的发生造成极大的经济损失.通过近几年对我省牙鲆流行病学的调查发现,牙鲆的腹水病发病率高达26%,仅次于盾纤毛虫疾病.针对这种情况,我们对我省牙鲆腹水病进行了病原学及防治方法的研究.     

大菱鲆与牙鲆盾纤类纤毛虫病的防治技术

盾纤类纤毛虫是一种严重危害大菱鲆与牙鲆的寄生虫性疾病,2000～2002年山东省文登市几家养殖场先后发生过此病,引起苗种及商品鱼大量死亡,死亡率高达70％以上,危害很大。现将我们掌握的情况介绍如下。     

Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean

The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna.     

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 performance,digestive enzyme activity and immune response of Japanese sea bass,Lateolabrax japonicus fed with fructooligosaccharide

In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg.     

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).     

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.     

Protein and amino acid composition from the mantle of juvenile O ctopus vulgaris exposed to prolonged starvation

Protein and amino acid composition of the mantle of juvenile O ctopus vulgaris (Cuvier, 1797) during fasting for 27 days were determined. Average protein content of octopus mantle was of 711.19 ± 46.80 g kg^?1 DW, and it decreased with increasing fasting days. The non‐essential amino acids content was higher (486.18 ± 11.08 g kg^?1 protein) than essential amino acids (425.82 ± 9.15 g kg^?1 protein) at the start of the experiment (unstarved animals). The results suggest that the amino acid profile of the mantle where the most abundant amino acids are Arg, His, Lys, Gly, Leu and Pro could indicate a prolonged fasting condition (>20 days) or poor nutrition of O . vulgaris. This study supports the idea of using mantle for metabolic needs of starved O . vulgaris suggesting that the degradation pathway of amino acids to pyruvate and tricarboxylic acid cycle intermediates was favoured contrary to the degradation pathway of ketogenic amino acids. Special considerations should be taken concerning Thr, Ile, Ser, Ala, Asx (Asp, Asn), Glx (Glu, Gln) (because of their fast intake) and Lys and His (due to their stable contents) during a prolonged period of fasting.     

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.