克氏原螯虾体表固着类纤毛虫种类调查及硫酸锌对其药效研究

调查克氏原螯虾(Procambarus clarkii)容易感染的固着类纤毛虫种类,并挑选寄生虫种类较单一的寄生部位分割成若干小块,分别放入不同浓度硫酸锌溶液,观察硫酸锌对固着类纤毛虫的药效。结果显示:容易感染克氏原螯虾的种类主要有钟虫、聚缩虫、累枝虫及莲蓬虫。硫酸锌对这几种虫体的24 h和48 h的LC_(50)分别为5.63和2.18 mg/L、5.01和2.44 mg/L、6.28和2.93 mg/L、3.23和1.72 mg/L,对硫酸锌敏感度莲蓬虫钟虫聚缩虫累枝虫。结果表明硫酸锌对克氏原螯虾常见固着类纤毛虫病有效。     

斑点叉尾鮰聚缩虫病防治试验报告

进行斑点叉尾鮰聚缩虫病防治试验,结果表明,用浓度为200mg／l甲醛（化学纯）浸泡30min,病鱼身上的聚缩虫杀灭率只有55％;而当病鱼先用浓度为200mg／l甲醛浸泡15min后,按20mg／l浓度添加高锰酸钾,再浸泡15min后,聚缩虫杀灭率达80％,经治疗后的病鱼平均存活率达82％。     

用双氯苯双胍已烷防治对虾聚缩虫病的研究

<正> 聚缩虫病害是中国对虾养殖明间常见的病害之一,发病率高,危害严重,特别是常与丝状细菌和藻类同时附着,影响对虾鳃丝的气体交换,个体消瘦,甚至发生死亡。该病防治方面的研究引起国内外有关专家的重视,如 Johnson(1973)和 Lightner(1977)曾提出福尔马林能有效地治疗对虾聚缩虫病,国内报道的有用0.5～1 ppm 的新洁尔灭与5～10ppm 的高锰酸钾混合用可杀灭聚缩虫以及用茶粕5ppm 促使对虾脱皮以达到除去聚缩虫之目的等等。我们曾选用福尔马林等药物试验,经多次筛选认为一些药虽     

报刊要闻

<正> 对虾纤毛虫病的防治江苏淡水水产所唐天德等撰文介绍了纤毛虫(聚缩虫、单缩虫、钟型虫、累技虫等)生长繁殖的条件、患病虾的特征和防治方法: 1.加强池水管理、保持水质清新;2.提高饵料质量、增强对虾体质;3.予防与药物治疗相结合,在养虾的中、后期,每周用苏SH—Ⅱ药或添加稀土甲壳素的颗饵连喂3天,每天2次,同时用苏SH-Ⅱ药连续予防;一旦纤毛虫类大发生,治疗方法是先降低虾池水1/3～2/5,用0.5～lppm的苏SH-Ⅱ连续处理3天.也可用碱性品录或新洁尔灭加高锰酸钾混合处理.一般很快能治愈。     

福尔马林防治大黄鱼刺激隐核虫病的研究

为合理使用福尔马林防治大黄鱼刺激隐核虫病,研究福尔马林对体外刺激隐核虫的灭活效果,并评估其对大黄鱼幼鱼的安全质量浓度范围。结果显示,对幼虫分别药浴处理10、30、60、120min,使幼虫全部死亡的福尔马林质量浓度分别为62.5、62.5、31.3、5.6mg/L;对包囊药浴处理1、2、4h,使包囊全部死亡的福尔马林质量浓度分别为150、75、75mg/L;福尔马林对大黄鱼(3.00±0.78)g幼鱼12、24、48、96h的半致死质量浓度分别为394.7、365.3、334.4、322.8mg/L;治疗试验显示,125mg/L福尔马林药浴2h,可有效防治大黄鱼刺激隐核虫病,存活率显著高于75mg/L组和对照组。试验结果表明,每隔3d,125mg/L的福尔马林药浴处理大黄鱼2h,共3次,可安全有效防治大黄鱼刺激隐核虫病。     

高锰酸钾防治对虾幼体聚缩虫病的研究

在对虾育苗期间,以选择施用0.5ppm和1ppm高锰酸钾、换水补药的方式为预防措施,以泼洒2～4ppm高锰酸钾短期药浴为应急治疗方法,连续2年在对虾育苗生产中取得了抑制和杀灭聚缩虫病成功率为100％,每立方水体生产15～25万尾仔虾的良好效果。育苗水体长期施用0.5～1ppm高锰酸钾对对虾幼体、单胞藻、卤虫无毒害作用,对微粒饵料、水质因子亦无不良影响。高锰酸钾施用方便,成本低廉,投入成本只占万尾虾苗售价的万分之一左右,便于在大生产中推广应用。     

河蟹人工育苗期固着类纤毛虫病的防治

河蟹人工育苗期间，受精卵和状幼体用抗真菌药物制霉素药浴，对固着类纤毛虫病的防治效果显著。当药液浓度在３５ｍｇ／Ｌ时浸浴３ｇｍ在６５ｍｇ／Ｌ时浸浴２ｈ，在１２５ｍｇ／Ｌ时浸浴１ｇ，均能杀死固着在蟹卵及幼体上的钟虫Ｖｏｒｔｉｃｅｌｌａｓｐ和聚缩虫Ｚｏｏｔｈａｍｎｉｕｍｓｐ．，并使虫体脱落。蟹卵和状Ｉ期幼体用１２５ｍｇ／Ｌ制霉素药浴６ｈ亦无融作用，受精卵的胚胎发育及幼体的蜕皮变态均正常。     

丁香酚对日本黄姑鱼麻醉效果的研究

为研究丁香酚对日本黄姑鱼的麻醉效果,用体长95 mm的日本黄姑鱼进行了麻醉试验。结果表明,水温25～26℃时,5 mg/L浓度的丁香酚药液对日本黄姑鱼只能起到轻度镇静作用;浓度在10～50mg/L时,浓度与麻醉所需的时间呈负相关,与复苏时间呈正相关;最理想的麻醉浓度为20～40 mg/L。鱼体在浓度20～30 mg/L的丁香酚药液中药浴15 min,能全部复苏;在浓度40 mg/L下药浴9 min,能全部复苏。采用浓度20～30 mg/L的丁香酚药液对鱼体深度麻醉后,鱼体在空气中暴露9 min后能全部复苏,且复苏时间随着药液浓度的升高而变长。     

几种常用渔药对三疣梭子蟹Portunus trituberculatus(Miers)稚蟹的急性毒性试验

采用常温静水实验法.对Ⅰ～Ⅱ期梭子蟹稚蟹(平均体长0.2～0.3 cm)进行急性毒性试验,结果表明:在水温26.2～27.8℃F,6种渔用药物对梭子蟹Ⅰ～Ⅱ期稚蟹的96 h半致死浓度(96 h LC50)分别为硫酸铜1.4 mg/L、纤虫清2.5 mg/L、清苔净16 mg/L、二氧化氯3.7 mg/L、强力杀菌消毒剂4.2 mg/L、二溴海因36.8 mg/L;安全浓度(Sc)分别为硫酸铜0.47 mg/L、纤虫清0.62mg/L、清苔净4.1 mg/L、强力杀菌消毒剂1.1 mg/L、二氧化氯1.1 mg/L、二溴海因13 mg/L.梭子蟹对上述药物的敏感性分别为硫酸铜＞纤虫清＞三氯异氰尿酸钠＞二氧化氯＞二溴海因＞清苔净.其中硫酸铜、纤虫清的安全浓度相对较低,在梭子蟹养殖过程当中应谨慎使用.     

青虾病害防治技术

一、固着类纤毛虫病1.症状早期少量虫体寄生时没有症状。严重寄生时,虾体表有许多绒毛状物,反应迟钝,行动缓慢,呼吸困难,手摸体表和附肢有滑腻感。2.病原纤毛虫病种类很多,常见病原体为累枝虫、聚缩虫、钟虫等。3.防治方法(1)纤虫净全池泼洒,药量为0.3克/米3,病情严重隔1～2天后再重复1次。(2)高锰酸钾化水全池泼洒,药量为3～7克/米3,4～5小时后进行大换水。(3)硫酸铜化水全池泼洒,药量为0.5克/米3。     

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).     

Evaluation of a Fast Method Based on the Presence of Two Restriction Sites in the Mitochondrial ND5 (mt ND5) Gene for the Identification of Scomber Species

The purpose of this work was to evaluate the suitability of a method based on the presence of two restriction sites (for Hae III and Hindf I) in the mitochondrial NADH dehydrogenase subunit 5 (mt ND5) gene to identify Scomber species. The evaluation was performed on 144 reference and market samples by sequencing of the entire 505-bp fragment of the mt ND5 gene and of a 464-bp fragment of the Kocher fragment of the cytochrome b gene (mt Cytb). Sequence analysis of any of the two fragments allows the identification of each of the four Scomber species, but S. japonicus and S. colias had the same restriction sites at the ND5 amplicon and would not have been differentiated by this analysis. Similarly, loss of the Hae III site in some S. scombrus individuals would have misidentified them as not being Scomber. All the market products were correctly labeled except one acquired in Spain labeled as originating in the Atlantic and containing S. japonicus.     

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.