转基因鱼试验湖浮游生物群落DNA指纹与理化因子的关系

对转基因鱼试验湖7个采样点的浮游生物群落进行了PCR-DGGE指纹分析,并进而探讨了DNA指纹与理化因子的关系.结果表明:(1)PCB-DGGE指纹图谱中共含104谱带,其中原核谱带58条,真核谱带46条,其多态性位点分别为87.9%和82.6%.(2)各站点的理化因子中,Ⅰ站的TP含量最高(0.10 mg/L),TN含量在Ⅲ站最高(0.34 mg/L),且各站点波动较大,Ⅴ站的透明度最低(63.00 cm);NO3-N、NH4-N、pH、DO、COD及电导率在各站点变化不大.基于原核生物图谱的相似性聚类分析表明,浮游生物群落Ⅵ和Ⅶ、Ⅳ和Ⅴ、Ⅱ和Ⅲ相似度分别较高,Ⅰ站有别于其它各站,单独为1枝;基于真核生物图谱的聚类分析显示,Ⅰ、Ⅱ站聚为1枝,Ⅳ、Ⅴ、Ⅵ和Ⅶ依次相聚后与Ⅲ站聚为另1大枝,Ⅰ、Ⅱ站与Ⅲ站相距较近;理化因子的主成分分析结果与之基本吻合.因此,浮游生物群落DNA多态性与环境理化因子是密切相关的,这类资料的积累将为在分子水平上建立水质预测预报体系奠定基础,为评价转基因鱼生态安全性提供依据.     

鲇鱼线粒体DNA的酶切图谱

采用差速离心法及ＤＮａｓｅⅠ、ＲＮａｓｅ消化法制备并纯化了鲇（Ｓｉｌｕｒｕｓａｓｏｔｕｓ）肝脏线粒体ＤＮＡ（ｍｉｔｏｃｈｏｎｄｒｉａｌＤＮＡ，ｍｔＤＮＡ）。用８种限制性内切酶对ｍｔＤＮＡ进行了分析。ＢｇⅡ、ＥｃｏｒⅠ、ＰｓｔⅠ、ＢｇｌⅠ、ＢａｍＨⅠ、ＸｂａⅠ、ＨｉｎｄⅢ、ＸｈｏⅠ在鲇ｍｔＤＮＡ分子上分别具１、１、１、２、２、７、７和０个切点。ｍｔＤＮＡ分子量约１０．８４×１０￣６道尔顿，大小为１７．５４ｋｉｌｏｂａｓｅｐａｉｒｓ。根据单酶和双酶解片段的数目和分子量，建立了鲇ｍｔＤＮＡ的限制性酶切图谱。     

氯化物水型盐碱池塘的限制性营养盐研究↑（*）

研究了沿黄盐碱地池塘水（ＣｌⅡＮａ 和ＣｌⅢＮａ） 的主要营养盐（Ｎ、Ｐ） 的限制作用和适宜施肥浓度。首次发现该类型池塘普遍表现为氮限制。塘水中无机氮浓度很低,只有（２３ ．５６ ±１２ ．５３） μｇ／Ｌ（ Ｍ±ＳＤ） ,与无机磷的比值仅为１ ．０２ ±０ ．８５ ;而总氮和总磷并不低,分别为（３ ．３５ ±１ ．０８） ｍｇ／Ｌ 和（０ ．２４ ±０ ．１１） ｍｇ／Ｌ;ＴＮ／ＴＰ为１４ ．９４ ±３ ．４３ 。适宜的施肥Ｎ∶Ｐ（ 重量） 为（１０ ～１５）∶１ 。文中提出了１ 种氮限制指数：ＩＮＬ＝ （ＤＯＩＮ１ ．０－ ＤＯＩｃ）／（ＤＯＩＮ１ ．０Ｐ０ ．１ － ＤＯＩｃ） ,并拟合出ＩＮＬ 与ＴＮ／ＴＰ的相关模型,ＩＮＬ 可准确地表示氮限制程度。文章最后分析了氮限制的原因。     

光合细菌在盐碱地池塘改良水质的研究

研究了光合细菌（ＰＳＢ）在低洼盐碱地池塘围隔中对水化因子和浮游生物的影响。结果表明：ＰＳＢ的施用对水化因子有较大的影响,其中水体中ＤＯ、ＮＯ３－－Ｎ升高,而ＮＨ４－Ｎ、ＮＯ２－－Ｎ、和ＣＯＤ降低,而对ＰＯ４３－－Ｐ影响不明显。当ＰＳＢ浓度高时,可提高水体的ｐＨ值;对浮游生物无明显影响;ＰＳＢ的一次施用量为１０ｐｐｍ,一次效用时间为６天左右,因而ＰＳＢ可达到改良水质,进而改善水质的目的,尤其在水质恶化时,其作用更显重要。     

大连市甘井子区北部沿海浮筏养殖水环境的初步观测

本文以１９９５年８～９月“太平洋牡蛎病害防治技术”的水环境调查资料为基础，初步分析了甘井子区北部沿海，在夏季高温期水体中理化要素（Ｔ、Ｓ、ＤＯ、ＣＯＤ、透明度），营养盐（ＮＨ３－Ｎ，ＮＯ２－Ｎ，ＮＯ３－Ｎ，ＰＯ４－Ｐ），及浮游生物量（叶绿量ａ）的含量和分布特征，介绍了各要素含量基本处于海水海水正常浓度水平，属于一类海水水质，海区营养水平为中等营养水平，是适宜的浮筏养殖区，但养殖规模应用有所限制。     

固定化光合细菌净化养鱼水质试验↑（*）

净化模拟养殖水质试验表明,固定化光合细菌可显著提高ＮＨ＋４ － Ｎ 和ＣＯＤ 的去除率,并能增加溶解氧。经１ 个月的鱼种饲养试验,固定化光合细菌（ Ⅲ组） 和游离光合细菌（ Ⅱ组） 鱼体重显著大于对照（ Ⅰ组） ,成活率也高于Ⅰ组。Ⅲ组效果最佳,不仅鱼体质好,活泼,个体较大且整齐,而且体色鲜艳。从水质分析结果看,Ⅲ组明显优于其它各组。     

INGESTIONANDEXCRETIONOFSEVERALANTIBACTERIALDRUGSBYTHEBRINESHRIMP（ARTEMIAPARTHENOGENETICA）1．TOXICITYT

ＩＮＧＥＳＴＩＯＮＡＮＤＥＸＣＲＥＴＩＯＮＯＦＳＥＶＥＲＡＬＡＮＴＩＢＡＣＴＥＲＩＡＬＤＲＵＧＳＢＹＴＨＥＢＲＩＮＥＳＨＲＩＭＰ（ＡＲＴＥＭＩＡＰＡＲＴＨＥＮＯＧＥＮＥＴＩＣＡ）１．ＴＯＸＩＣＩＴＹＴＯＡＲＴＥＭＩＡ，ＩＮＧＥＳＴＩＯＮＡＮＤＥＸＣＲ...     

鱼类细菌群落中的致病嗜水气单胞菌

鱼类细菌群落中的致病嗜水气单胞菌汤伏生，曾勇，张兴忠（中国水产科学院长江水产研究所．沙市４３４０００）朱晓燕（湖北农学院水产系，荆州４３４１０３）关键词鱼类，细菌群落，嗜水气单胞菌，致病性ＰＡＴＨＯＧＥＮＩＣＡＥＲＯＭＯＮＡＳＨＹＤＲＯＰＨＩＬＡＩＮ...     

岱海移植增殖大银鱼研究初报↑（*）

岱海移植增殖大银鱼研究初报ＰＲＥＬＩＭＩＮＡＲＹＳＴＵＤＩＥＳＯＮＴＲＡＮＳＰＬＡＮＴＩＮＧＯＦＢＩＯＷＨＩＴＥＢＡＩＴＳＴＯＤＡＩＨＡＩ任彩景２蓝学恒１冀喜平１张德斌１王岂伟２吴卫星１（１内蒙古乌兰察布盟水产站，集宁０１２０００）（２内蒙古凉城县...     

防病养虾塘水质管理模式

养殖中国对虾的试验塘，以防病养虾塘水质管理模式加以管理，养殖周期为８７－１５９天，取得较好的经济效益。虾塘水的主要理化因子基本符合要求，ＮＨ３－Ｎｔ〈１ｍｇ／，０．００５ｍｇ／Ｌ≤ＮＯ２≤０．０１６ｍｇ／Ｌ，溶氧处于过饱和状态，ＣＯＤＭｎ〈１２ｍｇ／Ｌ，池塘单位水柱毛产氧量约为７ｇ（ｍ＾２．ｄ），总耗氧量约为５－１１ｇ／（Ｌ．ｄ），并借助增氧机补足池水所缺需氧量。     

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.     

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.     

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.     

Effects of cortisol on hepatic carbohydrate metabolism and responsiveness to hormones in the sea raven,Hemitripterus americanus

The sea raven, Hemitripterus americanus, is a sit-and-wait, low metabolic rate, marine teleost. The objective of this study was to determine i) whether cortisol implantation (50 mg. kg^-1) for 7 days altered hepatocyte metabolism, and hepatocyte responsiveness to epinephrine, glucagon and insulin, and ii) whether 8 weeks of food-deprivation modified the above response. Cortisol implantation significantly increased hepatocyte total glucose production and oxidation from alanine compared to the sham group. There was no cortisol effect on glycogen breakdown, suggesting that the activation of other pathways, including gluconeogenesis, are required to account for the increased glucose production. Epinephrine-mediated (10^-5M) glycogen breakdown and insulin-mediated (10^-8M) total glucose production were enhanced in hepatocytes of cortisol implanted sea ravens, but there were no change in any glucagon (10^-7M) effects. The enhanced glycogen breakdown in the absence of similar increases in total glucose production with epinephrine indicates mobilization of carbohydrate reserves for endogenous use by the liver. Food-deprivation for 8 weeks significantly decreased condition factor, plasma cortisol concentration and liver glycogen content in the sea raven, but had no effect on plasma glucose concentration. Hepatocyte total glucose production and flux rates from alanine increased significantly with food-deprivation. Moreover, food-deprivation increased responsiveness of total hepatocyte glucose production to the actions of glucagon and insulin, but not to epinephrine; none of these effects were modified by cortisol implantation. Our results indicate that cortisol in the sea raven exerts both a direct and an indirect or permissive effect on hepatocyte metabolism by modifying hepatocyte responsiveness to epinephrine and insulin stimulation. Cortisol implantation did not modify the effects of glucagon or food-deprivation in this species.     

Simulation and quantification of enrichment and retention processes in the southern Benguela upwelling ecosystem

Important environmental processes for the survival and recruitment of early life stages of pelagic fishes have been synthesized through Bakun's fundamental triad as enrichment, concentration and retention processes (A. Bakun, 1996, Patterns in the Ocean. Ocean Processes and Marine Population Dynamics. San Diego, CA, USA: University of California Sea Grant). This conceptual framework states that from favourable spawning habitats, eggs and larvae would be transported to and/or retained in places where food originating from enrichment areas would be concentrated. We propose a method for quantifying two of the triad processes, enrichment and retention, based on the Lagrangian tracking of particles transported within water velocity fields generated by a three‐dimensional hydrodynamic model. We apply this method to the southern Benguela upwelling ecosystem, constructing putative maps of enrichment and retention. We comment on these maps regarding main features of the circulation in the region, and investigate seasonal variability of the processes. We finally discuss the results in relation to available knowledge on the reproductive strategies of two pelagic clupeoid species abundant in the southern Benguela, anchovy (Engraulis encrasicolus) and sardine (Sardinops sagax). Our approach is intended to be sufficiently generic so as to allow its application to other upwelling systems.     

Effects of capture,loading density and transport stress on the mortality,physiological responses,bacterial density and growth of rohu <Emphasis Type="Italic">Labeo</Emphasis><Emphasis Type="Italic"> rohita</Emphasis> fingerlings

This study evaluated the effects of three levels of loading density (200, 300 and 400 g L⁻¹) and four levels of duration (1, 3, 6 and 9 h) on the mortality, plasma cortisol and chloride levels and growth of rohu Labeo rohita fingerlings in a transport simulation. While total immediate mortality was low (4–12%), delayed mortality was high (27–49%). Initial capture and handling were found to constitute the most stressful phase as indicated by elevated plasma cortisol. The levels of cortisol continued to rise at 6 and 9 h after transport, with the highest level observed at 9 h after transport. The level of plasma chloride fell after transport across all density levels and treatment durations. Specific growth rate (SGR, %/day) and total bacterial density (cfu/g) were not different between and within treatments, and between treatments and the controls. This study demonstrates that transport has a profound effect on the stress responses of rohu fingerlings. Although the level of immediate mortality was low, the higher level of delayed mortality has serious implications in terms of production inefficiency for grow-out farmers.     

The effects of introduced tilapias on native biodiversity

• 1. The common name ‘tilapia’ refers to a group of tropical freshwater fish in the family Cichlidae (Oreochromis, Tilapia, and Sarotherodon spp.) that are indigenous to Africa and the southwestern Middle East. Since the 1930s, tilapias have been intentionally dispersed worldwide for the biological control of aquatic weeds and insects, as baitfish for certain capture fisheries, for aquaria, and as a food fish. They have most recently been promoted as an important source of protein that could provide food security for developing countries without the environmental problems associated with terrestrial agriculture. In addition, market demand for tilapia in developed countries such as the United States is growing rapidly.
• 2. Tilapias are well‐suited to aquaculture because they are highly prolific and tolerant to a range of environmental conditions. They have come to be known as the ‘aquatic chicken’ because of their potential as an affordable, high‐yield source of protein that can be easily raised in a range of environments — from subsistence or ‘backyard’ units to intensive fish hatcheries. In some countries, particularly in Asia, nearly all of the introduced tilapias produced are consumed domestically; tilapias have contributed to basic food security for such societies.
• 3. This review indicates that tilapia species are highly invasive and exist under feral conditions in every nation in which they have been cultured or introduced. Thus, the authors have concluded that, despite potential or observed benefits to human society, tilapia aquaculture and open‐water introductions cannot continue unchecked without further exacerbating damage to native fish species and biodiversity. Recommendations include restricting tilapia culture to carefully managed, contained ponds, although exclusion is preferred when it is feasible. Research into culture of indigenous species is also recommended.

Copyright © 2005 John Wiley & Sons, Ltd.