马拉硫磷和甲氰菊酯对萼花臂尾轮虫生殖的影响

研究了不同浓度马拉硫磷(malathion)(0.03、0.3、3.0、30.0、300.0、3000.0μg/L)和甲氰菊酯(fenpropath-rin)(0.004、0.04、0.4、4.0、40.0、400.0μg/L)对萼花臂尾轮虫(Brachionus calyciflorus)3d种群增长率、携卵雌体数/非携卵雌体数、混交雌体百分率、混交雌体受精率及7d休眠卵产量影响。结果表明,马拉硫磷、甲氰菊酯对种群增长率、混交雌体百分率、混交雌体受精率及7d休眠卵产量有显著影响;马拉硫磷对携卵雌体数/非携卵雌体数无显著影响,但甲氰菊酯有显著影响。马拉硫磷对轮虫休眠卵产量最低效应浓度(LOEC)为0.3μg/L,对混交雌体百分率LOEC为30.0μg/L,对种群增长率和混交雌体受精率LOEC为300.0μg/L;甲氰菊酯对轮虫休眠卵产量最低效应浓度0.04μg/L,对混交雌体百分率和携卵雌体数/非携卵雌体数LOEC为4.0μg/L,对种群增长率和混交雌体受精率LOEC为40.0μg/L。试验显示,马拉硫磷和甲氰菊酯对轮虫生殖存在差异,轮虫休眠卵产量可以用来监测和评价2种杀虫剂潜在的影响。     

轮虫在虾蟹育苗中的投喂技术

轮虫在分类中隶属轮形动物门,轮虫纲,在咸淡水电均有分布,繁殖快,生长迅速,尤其喜好肥沃的水环境,通常以浮游藻类、有机碎屑及微生物为食。其繁殖方式分孤雌生殖及有性生殖,在条件适宜时,行孤雌生殖,产生夏卵,在生存环境急剧恶劣时行有性生殖,产     

轮虫强化培养的研究进展

轮虫是海水鱼虾类苗种生产中的重要开口饵料。目前使用的轮虫主要有Ｂｒａｃｈｉｏｎｕｓｐｌｉｃａｔｉｌｉｓ(Ｌ型 )和Ｂ .ｒｏｔｕｎｄｃｆｏｒｍｉｓ (Ｓ型 )两种。由于海产小球藻等单细胞藻类的繁殖速度小于轮虫的摄食量 ,在大规模轮虫培养中单胞藻不能满足需要 ,制约了轮虫的生产。用酵母和含高度不饱和脂肪酸 (ＨＵＦＡ)的人工饵料是替代单胞藻最常用的办法〔1、2〕,但其必需脂肪酸 (ＥＦＡ)缺乏或不足 ,用作轮虫的饵料前需进行ＥＦＡ的强化〔3〕。目前 ,轮虫培养在ＥＦＡ强化、替代饵料、高密度培养、冷冻藻保存利用和休眠卵利用等…     

扁吻鱼人工繁殖技术研究

２００６～２００７年,利用人工驯化养殖３年以上的扁吻鱼（Ａｓｐｉｏｒｈｙｎｃｈｕｓｌａｔｉｃｅｐｓ）亲鱼,通过人工催产、流水刺激、人工采卵等方法,２年共采卵９９万粒,授精率８３．３％,孵化率６７．８％,室内人工孵化出苗５６万尾,初孵仔鱼全长０．７ｃｍ,水温１７～１９℃时,约６ｄ后开口摄食,开口饵料为轮虫或卤虫无节幼体。     

冷冻对轮虫休眠卵萌发率的影响

对在不同冷冻时间和冷冻强度下臂尾轮虫休眠卵的萌发率进行了测试,结果显示,褶皱臂尾轮虫（ Ｂｒａｃｈｉｏｎｕｓ ｐｌｉｃａｔｉｌｉｓ） 休眠卵在－ １８ ℃冷冻２０ ｄ ,萌发率提高１３ ．９ ％ ;－ ３０ ℃冷冻６０ ｄ ,萌发率提高１４ ．４ ％ ;室外经整个冬季冻后,萼花臂尾轮虫（ Ｂ．ｃａｌｙｃｉｆｌｏｒｕｓ） 、壶状臂尾轮虫（ Ｂ．ｕｒｃｅｕｓ） 休眠卵的萌发率平均提高了１ ～３ 倍,而角突臂尾轮虫（ Ｂ．ａｎｇｕｌａｒｉｓ） 的萌发率却降低了近１ 倍。－ ８０ ℃强冷冻２ ｄ,褶皱臂尾轮虫休眠卵萌发率从３９ ．５ ％ 降至１ ．６ ％ 。同时,本文探讨了冷冻影响轮虫休眠卵萌发的机理以及冷冻处理在北方轮虫土池生产中的实际意义。     

生物饵料的n－3 PUFA营养强化技术

生物饵料的ｎ－３　ＰＵＦＡ营养强化技术张利民（山东省海洋水产研究所，烟台２６４０００）在海水鱼虾育苗过程中，轮虫（Ｂｒａｃｈｉｏｎｕｓｐｌｉｃａｔｉｌｉｓ）和卤虫（Ａｒｔｅｍｉａｓａｌｉ－ｎａ）是重要的生物饵料，而不同的养殖种类对营养需求不一样，例如...     

两种消毒剂处理对萼花臂尾轮虫休眠卵萌发的影响

在特定条件下形成的轮虫休眠卵,经过一定时间的储藏保存,其萌发率均有不同程度的降低[1,2]1)。已有研究表明,大量的细菌污染是导致褶皱臂尾轮虫(Ｂｒａｃｈｉｏｎｕｓｐｌｉｃａｔｉｌｉｓ)休眠卵萌发率降低的主要因素之一;使用适宜种类和浓度的消毒剂处理可显著地提高其萌发率[3]。有关淡水轮虫休眠卵的报道较少,为此我们使用扫描电子显微镜对萼花臂尾轮虫(Ｂｒａｃｈｉｏｎｕｓｃａｌｙｃｉｆｌｏｒｕｓ)休眠卵进行观察,并用不同种类和浓度的消毒剂对其进行消毒实验,旨在为轮虫休眠卵的有效保存和使用提供依据。1　材料和方法1.1　轮虫休…     

投喂酵母和扁藻类培养褶皱臂尾轮虫的效果试验

实验室条件下，分别以面包酵母和扁藻为饵料培养褶皱臂尾轮虫（以下简称轮虫）。结果表明，轮虫摄食扁藻的生长繁殖效果要好于摄食酵母。以扁藻为食物，其带卵率和带卵数分别为45．5％和3．1个，而以酵母为食物，其带卵率和带卵数仅分别为32．5％和2．2个。在轮虫接种密度情况下（经一个培养周期7天），轮虫密度分别为54个／ml、32．5／ml。     

冷冻对轮虫休眠卵上浮率的影响↑（*）

本文报道了冷冻对轮虫休眠卵在水中上浮率的影响，一次冷冻（２４小时）可使各种轮虫休眠卵在水中的上浮率平均提高近５０％，使晶囊轮虫休眠卵的上浮率提高９０％左右。多次反复冷冻能使各种轮虫休眠卵的上浮率提高８５％左右，冷冻时间在８～１０４小时间，延长冷冻时间不会影响轮虫休眠卵的上浮率，并分析了冷冻处理后的休眠卵在水中和糖盐高渗液中上浮率提高的机理，讨论了冷冻处理在轮虫休眠浮选，定量以及土池轮虫生产中的意义     

中国西北地区内陆盐湖卤虫卵径研究

本文研究了新疆维吾尔自治区（简称新疆）,青海省和内蒙古自治区（简称内蒙古）20处盐湖卤虫品系的卵径。其结果如下：1．20个卤虫品系中属于两性生殖类型的有13个品系,7个品系为孤雌生殖类型;2．两性生殖类型的卤虫卵径小于孤雌生殖类型的卵径。两性生植类型的卤虫干燥卵径平均为218．2±9．8μm,水合4h后的平均卵径248．9±12．5μm,消亮后的卵径平均为230．4±12．7μm,卵壳厚度平均为9．3±2．4μm。孤雌生殖类型的卤虫干燥卵径平均为245．6±7．6μm．吸水4h后的卵径平均为277．8±7．2μm,消壳后的卵径平均为260.8±6．2μm,卵壳厚度平均为8.5μm。经t值检验．不同生殖类型间的卵径差异非常显著（a＝0．01）。而卵壳厚度,两者之间差异不显著;3．孵出2h内的卤虫无节幼体体长：两性生殖类型平均为440.2±31．0μm,孤雌生殖类型为491．4±20．6μm。经t值检验,差异非常显著。     

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.