微波消解/ICP-MS法同时测定贝类产品中16种金属元素的含量

本文建立了微波消解-电感耦合等离子体质谱(ICP-MS)同时测定贝类产品中Cr、Mn、Fe、Co、Ni、Cu、Zn、As、Se、Mo、Ag、Cd、Ba、Hg、Tl和Pb等16种金属元素含量的方法.采用微波消解法对样品进行消解,通过在线加入内标校正基体效应,利用ICP-MS测定贝类产品中16种金属元素的含量.测定元素校正曲线的相关系数均在0.9992以上,检出限为6.64× 10-4 ～0.0851 μg· L-1.对牡蛎样品平行测定6次,各元素相对标准偏差(RSD)均小于5％.利用该方法分析了标准参考物质扇贝(GBW10024)中的16种金属元素,其测定值与参考值吻合.该方法具有快速、简单、精密度和准确性良好等优点,适用于贝类产品多种金属元素的同时测定.     

湛江市场食用鱼类和甲壳类重金属的检测与评价

通过硝酸一过氧化氢作消解液微波消解处理样品,采用ICP-AES法测定湛江海域鱼类和甲壳类样品中Zn、Cd、As、Cr、Cu等重金属含量,并根据相应标准对重金属含量进行评价及食用安全评估。调查结果显示,重金属在不同种类海产品中的分布情况有所不同,被调查的种类海产品中各种重金属（除鱼类中的Cd）含量均低于“海洋生物污染评价标准”,鱼类和甲壳类的Cd含量则高于“人体消费卫生标准”。对消费者的健康构成了严重的威胁,应该引起重视。     

象山港、三门湾菲律宾蛤仔重金属含量初步分析

在象山港和三门湾采集菲律宾蛤仔样品30份和20份,测定其重金属含量。结果表明,以平均值计,Hg为0.0440和未检出、Cd0.0722和0.0624、As1.1048和1.7045、Pb0.1245和1.0577、Zn10.7410和11.5000、Cu1.4322和1.0577、Cr0.2357和0.1119。对其结果经统计学处理,表明象山港的菲律宾蛤仔的Hg、Cu、Cr含量比三门湾高,而As却相反,其它Zn、Cd、Pb无显著性差异。     

几种海洋药用动物中重金属元素的含量分析

对我国几种传统海洋药用动物中重金属元素的含量进行了测定,并对同产地的陆生药用动物蛤蚧进行比较研究,其中Hg和As利用原子荧光光度计测定,Pb、Cd、Cu、Fe、Mn、Zn利用原子吸收光度计测定,样品采用微波消解仪消解。结果表明:海钱、海蛇、海马、海星的镉含量较高,海燕、海马、海星的铅含量较高,除个别样品微量元素未检出外,样品中Fe、Mn、Zn的含量相对较高。最后对金属元素含量较高的原因及对所含微量元素的食用安全性和营养学评价进行了探讨。     

大连沿海虾夷扇贝体内重金属含量研究与质量评价

用微波消解对大连沿海虾夷扇贝样品进行处理,电感耦合等离子体质谱法测定虾夷扇贝不同组织中重金属Pd、Cd、Hg、Cr、Cu、Zn的含量,同时对重金属含量进行质量评价。试验结果表明,Pd、Cd、Hg、Cr、Cu、Zn在不同海域虾夷扇贝中的含量相差较大,6种重金属的平均含量分别为0.488、2.924、0.047、1.394、2.152、36.08mg/kg,即ZnCdCuCrPbHg。虾夷扇贝不同组织蓄积重金属具有明显的差异性,闭壳肌中重金属Cd、Cu的含量显著低于其他组织,Zn的含量却高于内脏团,不同组织对Cr的蓄积程度差异较小。调查发现,虾夷扇贝中重金属Cd的含量较高,尤其内脏部分远超过我国无公害水产品中有毒有害物质限量,建议食用虾夷扇贝时去除内脏团。     

长江口九段沙无齿相手蟹体内重金属含量与评价

以九段沙湿地生态系统中常见的无齿相手蟹为研究对象,分析了其体内重金属的积累和分布特性.结果表明,其体内重金属含量顺序为Cu＞Zn＞Cd＞Pb＞Cr＞As＞总Hg,其重金属含量存在一定季节差异;对九段沙沉积物中的重金属含量分析表明,无齿相手蟹对Cu和Cd有一定的富集能力,适合做九段沙湿地Cu和Cd的指示生物;污染评价表明,本研究中无齿相手蟹均已受到Cu和Pb污染,部分受到Zn、Cd和Cr污染,但未受Hg和As污染.     

微波清解——石墨炉原子吸收法研究海湾扇贝中金属的富集效应

采用微波消解对海湾扇贝样品进行处理,用原子吸收光谱仪测定海湾扇贝各组织中重金属Ph、Cu、Cd含量。结果表明：微波消解一石墨炉原子吸收法能准确测定海湾扇贝体内Ph、Cu、Cd含量。消化液无色透明、无残渣,消化完全。内脏中Pb、Cu、Cd含量最高。从饮食安全角度来讲,食用贝柱比食用整体贝肉安全。     

黄河口附近海域表层沉积物重金属污染状况及年际变化分析

根据2006-2014年共5个航次在黄河口附近海域采集的150个调查站位的表层沉积物样品的监测结果,对沉积物中Hg、Cu、Pb、Cd、Cr、Zn和As共7种重金属元素的含量及年际变化趋势进行了分析,采用单因子标准指数法和潜在生态风险指数法对重金属污染状况和潜在生态风险程度进行了评价.结果显示,7种重金属的含量除2011年少数调查站位的Cu和Pb超过第一类标准外,其他调查站位的重金属含量均符合海洋沉积物质量第一类标准.重金属Hg和Cd的含量相当,其含量明显低于其他5种重金属元素.7种重金属含量的年际变化有所不同,年平均单因子标准指数均小于1,表明调查海域表层沉积物质量状况良好.7种重金属元素的年平均单因子标准指数排序为Cu＞Cr＞As＞Pb＞Cd＞Hg＞Zn;其中,Cu的标准指数值较高,近10年来其标准指数均值达0.61,应引起重视并加强例行监测;其他6种重金属元素的单因子标准指数均值均小于0.4.潜在生态风险评价结果显示,各航次7种重金属的平均潜在生态风险系数Eir均小于40,属于低生态风险水平;7种重金属近10年平均Eir排序为Hg＞Cd＞As＞Pb＞Cu＞Cr＞Zn;其中,Hg是该调查海域的主要潜在生态风险因子.综合潜在生态风险指数RI的年际变化范围为32.18-53.12,属于低生态风险水平;RI的年际变化趋势基本表现为先升高后降低、然后略微上升的趋势.     

燕尾港近岸海域表层沉积物重金属的分布与污染评价

测定了燕尾港近岸海域表层沉积物中重金属的含量,运用地累积指数就其污染程度进行了分析与评价。结果表明Cu、Zn、Pb、Cd、Cr、As、Ni、Mn的平均含量分别为20．2,264,54．0,1．52,69．8,38．8,35．7,684 mg/kg。Cu、Zn、Pb、Cr、As的平均含量低于国家海洋沉积物质量标准的二级标准值,重金属Cd的平均值高于国家海洋沉积物质量标准的二级标准值;地累积指数评价结果表明,Cd在调查海域污染程度重,7种重金属的污染程度依次为Cd＞ As＞ Pb＞Zn＞Cr＞Ni＞Cu。对结果进行主成分分析和聚类分析后发现,前2个主成分的贡献率分别为62．41％、12．52％,表明此海域表层沉积物中重金属的主要来源是工业废水和农业灌溉水的排放及大气沉降。     

连云港近岸海域表层沉积物中重金属的赋存形态

对连云港近岸海域6个表层沉积物样品中重金属(Cu、Zn、Cr、Ni、Pb、Cd)的含量及赋存形态进行分析。结果表明该海域表层沉积物中重金属Pb和Cr的浓度水平超出国家海洋一类沉积物质量评价标准,其余重金属的浓度达到海洋一类沉积物质量标准。采用Tessier连续提取法发现,连云港近岸海域表层沉积物中重金属各形态的分布存在很大的差别,重金属Cu以有机态为主要赋存形态,Cr和Ni以残渣态为主要赋存形态,Pb主要以铁锰氧化物态为主,重金属Cd以可交换态为主,Zn主要以非残渣态为主。以生物有效性和迁移性来综合评价重金属的生物活性,发现该海域Cd的生物活性和迁移性最大。此次研究对该海域表层沉积物中重金属的赋存形态特征有了基本了解,有助于进一步研究金属元素在近海环境中的迁移和形态转化机制,也为评价近岸海域表层沉积物中重金属的危害提供科学依据。     

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.