斑马鱼和鲢鱼对微囊藻毒素与孔雀石绿的行为反应

鱼类行为能准确地反映环境变化,并且随着污染物浓度的变化而发生改变,因此将毒素敏感鱼类的行为作为标记,用以监测环境是可行的。本研究用人工饲养,对环境毒素敏感的斑马鱼和对环境毒素有较强吸收能力的鲢鱼作为指示生物,检测其行为对水体中微囊藻毒素(MC)和孔雀石绿(MG)的反应。结果表明,斑马鱼和鲢鱼在2 µg/L MC浸泡下未出现显著的行为反应,而在5 µg/L的MC浸泡下,斑马鱼摆尾频率在10 min 后,移动速度在40 min后显著性下降;鲢鱼摆尾频率与移动速度均在40 min后显著性下降。另一方面,0.5 mg/L MG处理下,斑马鱼未出现显著性行为变化,而鲢鱼摆尾频率与移动速度均在35 min后显著性下降。     

微囊藻毒素及其生殖毒性的研究进展

工业化、城市化的发展以及农业生产中大量化肥的使用,使自然界许多水体的污染逐渐加重,出现富营养化现象,导致藻类尤其是蓝藻的过度繁殖生长,不仅破坏了水生生态系统,而且对经济和社会发展、环境以及人类健康的影响很大[1-6]。蓝藻广泛地生长在世界各地的水体中,某些种类的蓝藻     

微囊藻毒素在鲤体内富集的初步研究

为了解微囊藻毒素MC-LR在鲤各组织器官中的生物富集作用,采用腹腔注射法将MC-LR纯品稀释液(0.215μg/g)注射到鲤体内,酶联免疫吸附法(ELISA)检测0、1、3、12、24和48 h时肾脏、肝脏、肌肉、胆囊、空肠和卵巢中MC-LR含量分布和积累规律.结果显示,MC-LR在肾脏含量最高,均值为(1.007±0.120)μg/g(各器官均按干重计),其次是肝脏(0.490±0.060)μg/g、胆囊(0.355 ±0.011) μg/g、空肠(0.210±0.005)μg/g、卵巢(0.082±0.021)μg/g和肌肉(0.047±0.003) μg/g.鲤不同组织器官对MC-LR的富集能力存在较大差异,肾脏是MC-LR的主要靶器官,卵巢中也存在少量MC-LR富集,肌肉对MC-LR的生物富集量远低于其他组织器官.试验48 h时,鲤体内各组织器官中和鱼缸水中MC-LR含量均有一定程度的下降,表明鲤体内对MC-LR有较强的解毒机制.     

微囊藻毒素对金鱼胚胎发育的影响

将发育至卵裂期的金鱼胚胎暴露于不同浓度的微囊藻毒素中。结果显示。金鱼胚胎的孵化率逐渐降低,而畸形率升高,且毒素致畸的半数有效质量浓度EC50=2866．2μg/L。主要畸形症状是：胚体浑浊、模糊或自行解体,弯体,弯尾。孵化异常。卵黄破裂逸出等。     

微囊藻毒素对小白鼠肝脏的毒理效应

以微囊藻体内提取的微囊藻毒素(MC)试液对ICR小白鼠进行腹腔注射实验，小白鼠肝脏充血、肿胀，出现死亡。通过电子显微镜对肝细胞超微结构观察，实验表明，MC试液使小白鼠肝细胞超微结构出现较大异常变化，内质网破碎，发生核糖体的脱粒现象；线粒体内部结构尤其是嵴发生变形、碎裂，出现溶解。解体的部分内质网碎片包绕在线粒体周围，细胞内容物稀疏，细胞质结构分布比较随机，规律性降低。研究结果表明，MC—LR的腹腔注射剂量为0．06mg／kg时，会使ICR小白鼠肝细胞超微结构有显著变化并出现小白鼠死亡现象。     

高铁酸钾对微囊藻毒素的去除效果探讨

研究高铁酸钾对微囊藻毒素（MC—LR）的去除效果,探讨不同反应影响因素（反应时间、K2FeO4质量浓度、温度和pH）对去除率的影响。结果表明,K2FeO4能够有效地去除水中的MC—LR。K2FeO4对MC—LR的去除率与K2FeO4。投加质量浓度、反应时间成正相关,其中K2FeO4质量浓度对去除效果的影响较为明显;反应温度对去除率的影响不显著;pH对去除率也有重要影响,当pH分别为2和10时去除率分别为94．51％和87．96％。正交试验的结果也进一步证明了不同反应影响因素对去除效果的影响显著程度。     

微囊藻毒素的研究进展

随着环境污染的加剧,自然界的许多水体日益福营养化,水体的福营养化直接导致了藻类的迅猛生长,严重影响了水的质量[1].淡水藻类中蓝藻的过度繁殖,会造成水味腥臭、透明度下降、消耗水体溶解氧,其中的微囊藻属、颤藻属、鱼腥藻属、念珠藻属等藻类自身及其代谢产物有毒性和致癌作用,危害人体健康[2].研究发现,蓝绿藻水华中的微囊藻毒素与人群中的肝癌有密切的关系[3～5].     

微囊藻毒素对小鼠肝脏的毒性研究

为研究微囊藻毒素(MC)对小鼠肝脏的影响,采用腹腔注射MC抽提物,剂量分别为对照、MC3.33μg/(kg.d)和6.67μg/(kg.d),注射MC抽取物14 d后发现,与对照组小鼠肝脏相比,注射MC抽提物的小鼠肝脏肿大,且随注射剂量的增加,小鼠肝脏的相对质量增加,肝脏的黏连程度更加明显。     

三氯异氰脲酸对铜绿微囊藻的毒性效应

研究了三氯异氰脲酸对铜绿微囊藻的生长、叶绿素含量、光合放氧和呼吸耗氧的影响.结果表明,三氯异氰脲酸对铜绿微囊藻具有很强的杀死效果,其浓度愈大效果愈明显,12.0mg/L时杀藻率达100%,而浓度低时,虽也有一定的效果,但由于有效氯的衰减,其杀藻不能持续很长时间.三氯异氰脲酸能降低铜绿微囊藻的光合放氧,但随着时间的延长,光合放氧的抑制作用降低;叶绿素a含量下降程度大于光合作用减弱程度,光合作用的抑制是通过抑制藻叶绿素a的合成而实现的.     

微囊藻毒素对凡纳滨对虾肝胰腺氧化损伤研究

在水温(22±1)℃、pH 8.0～8.5、溶解氧7～8 mg/L下,对体质量(16.0±1.0) g凡纳滨对虾注射浓度为3.52×10^-4 mmol/kg的微囊藻毒素20μL。分别于注射后0、2、4、8、16、24、48、72 h测定凡纳滨对虾死亡率,并取肝胰腺组织,检测其超氧化物歧化酶、过氧化氢酶和谷胱甘肽过氧化物酶3种抗氧化酶活性及丙二醛含量的变化,研究微囊藻毒素对凡纳滨对虾肝胰腺相关免疫酶活性的影响。试验结果显示：注射微囊藻毒素后,凡纳滨对虾72 h死亡率为13.33%;凡纳滨对虾肝胰腺中丙二醛含量逐渐升高,8 h后显著高于对照组,并于72 h达到最大值(4.02±0.02) nmol/mg(P<0.05);超氧化物歧化酶、过氧化氢酶及谷胱甘肽过氧化物酶活性在72 h内均呈先升后降的趋势,并分别在2、4、8 h达到最高,随后活性逐渐降低,16 h后逐渐低于对照组,且活性均于72 h达到最低值。试验结果表明,微囊藻毒素导致凡纳滨对虾肝胰腺脂质过氧化反应逐渐增强并抑制凡纳滨对虾抗氧化相关酶活性,造成氧化应激,72 h内便会造成肝胰腺严重氧化损伤。     

Effects of the wood extractive betulinol and 17beta-oestradiol on reproduction in zebrafish, Danio rerio (Hamilton)--complications due to a bacterial infection

Zebrafish were exposed to the wood extractive betulinol (5 microg L(-1)) and to 17beta-oestradiol (E2, 0.27 microg L(-1)) for 8 weeks in an attempt to study the possible endocrine-disrupting activity of betulinol. Females exposed to betulinol showed increased spawning intensity, while males exposed to betulinol and E2 had increased incidences of structural alterations in the testes. However, histological examination of the fish revealed that they were infected by acid-fast bacteria suspected to be Mycobacterium sp. despite a careful examination of their health state prior to the onset of the experiment. Fish exposed to betulinol and E2 showed more serious consequences of the bacterial infection than control fish indicating that the test chemicals had weakened the immune defence of the fish. When the exposure was repeated with healthy fish, an increase in the proportion of spermatogonia was seen in the testes of betulinol-treated males. A similar alteration, although not statistically significant, was also seen in the first experiment. However, no increase in the incidences of structural alterations in the testes was seen in betulinol- and E2-treated fish in the second experiment. Our study indicates that betulinol might have an endocrine-disrupting effect in zebrafish, but the increase in incidences of structural alterations in the testes might have been caused by a synergistic action between the test compounds and the bacterial infection. Our study stresses the importance of carefully checking the health of experimental fish, not only prior to the onset of an experiment but also upon termination of the experiment, in order to avoid misinterpretation of the results.     

Exposure to 17α,20β-dihydroxy-4-pregnen-3-one changes seminal characteristics in Nile tilapia, Oreochromis niloticus

This experiment was conducted to evaluate the seminal characteristics of Nile tilapia males exposed to water‐borne 17α,20β‐dihydroxy‐4‐pregnen‐3‐one (17,20βP). Male Nile tilapia (Oreochromis niloticus L.) were exposed to the steroidal pre‐ovulatory pheromone 17,20βP, added to water at a concentration of 5×10^?9 M. The pheromone‐exposed males had higher sperm volume and concentration. In addition, the spermatozoa contained in the sperm had higher motility and the motility duration was longer than ethanol‐exposed males (control group). The percentage of live spermatozoa was not affected by the treatments. Our results suggest that this pheromone can improve sperm quality characteristics and could become a non‐invasive method for enhancing spawning in Nile tilapia.     

Fluctuations of perch populations in Lake Geneva from 1984 to 2011 estimated from the number and size of egg strands collected in two locations exposed to different fishing practices

Fluctuations in the number and size of spawning perch (Perca fluviatilis) in Lake Geneva were evaluated and compared each year from 1984 to 2011 in two locations. This evaluation was based on: (1) each mature female lays only one egg strand per year and (2) the number and size of mature females are well correlated with those of their egg strands. Egg strands were counted and measured at two locations in France and in Switzerland. The collection of egg strands from either artificial substrates (France) or by direct sampling of the natural lake bottom by a diver (Switzerland) did not seem to affect the results. In most years the number and mean width of egg strands fluctuated in the same way in both locations. In addition, yearly perch catches were correlated with the number of egg strands at both locations. However, more small egg strands were found in France than in Switzerland, whereas the reverse was true of large egg strands. Fishing pressure concentrated to a greater extent on small perch in France than in Switzerland could explain this difference.     

Artificial reproduction protocol,from spawning to metamorphosis,through noninvasive methods in Patella caerulea Linnaeus, 1758

Controlled reproduction is a requirement for developing effective mollusc cultivation for commercial or restoration purposes. In this study, a protocol for spawning induction using noninvasive methods in limpets was developed, using the common Mediterranean species, Patella caerulea Linnaeus, 1758. Six nonlethal spawning induction treatments were tested: three chemical (two concentrations of H₂O₂ and KCl) and three physical (bubbling, warm and cold thermal shock). All treatments, except thermal shocks, induced the spawning of fertile gametes. Bubbling resulted the best treatment in providing spawning response, being the easiest and least invasive method tested. After eggs fertilization, larval development was followed until metamorphosis, testing fed and unfed conditions. Settlement took place after 7 days. The developed protocol represents a benchmark for further application to other limpets, for aquaculture or repopulation.     

Induction of mRNAs in response to acclimation of trout cells to different osmolalities

The direct effect of osmolality on growth and mRNA population were investigated in the rainbow trout cell line (RTG-2). These cells can grow in the media of osmolalities ranging from 200 to 600 mosmol kg-1. With two-dimensional electrophoresis, the in vitro translation of poly(A⁺) RNA isolated from these cells showed osmoresponsive changes in the population of translatable mRNAs. Using differential mRNA display polymerase chain reaction, however, we identified inducible cDNA products in hyper-osmotic and hypo-osmotic media as third component of complement, and as homologues of known genes: an atypical protein kinase regulated by the thyrotropin-dependent mitogenic pathway, nucleolin and CHD3. The remaining cDNAs have no significant homology in GenBank. Northern blots demonstrate that their mRNA levels were induced in hyper-osmotic and hypo-osmotic media, but not by other stresses. The expressed proteins of these mRNAs may be involved directly or indirectly in the adaptation of RTG-2 cells to different osmolalities probably through the osmotic signal transduction and adjustment in cellular metabolism to osmotic stress.     

Optimal Conditions to Remove Chemical Hazards in Fish Protein Isolates from Tilapia Frame Using Response Surface Methodology

Response surface methodology (RSM) was employed to maximize the removal of phospholipids (PLs) and other chemical hazards in tilapia protein isolates made from tilapia frame (TF). CaCl₂ and the ratio of water to minced tilapia frame (W:TF) were the significant variables affecting PLs reduction. The optimum condition for maximal PLs reduction (90.0%) was: 10.25 mM CaCl₂ and a W:TF of 7.8:1, while other variables were fixed at 5 mM citric acid, 60 min incubation, pH 11, and centrifugal speed of 8,000 × g. At these conditions, the great reduction of lipids (93.9%), Hg (97.6%), and As (95.5%), as well as 86.1% of protein recovery, were obtained. Protein isolates with significantly reduced chemical hazards and lipids were successfully prepared from tilapia frames using the alkaline extraction assisted with CaCl₂ and citric acid.     

Effect of feeding level on growth and nutrient deposition in rainbow trout (Oncorhynchus mykiss Walbaum) growing from 150 to 600 g

The effects of feeding level on growth and energy partitioning were studied in rainbow trout growing from 150 to 600 g. Triplicate groups of fish (initial weight 158 g fish^?1) were fed a practical diet at various feeding levels (25%, 50%, 75% and 100% of near satiation) for 24 weeks at 8.5°C. The final body weights of fish were 235, 381, 526 and 621 g. Restricted feeding levels significantly reduced live weight gain. Feeding levels had less pronounced effects on feed efficiency ratio, which were 0.98, 1.08, 1.02 and 0.83, respectively, for the 25%, 50%, 75% and 100% feeding levels. The growth of fish fed to near satiation was accurately described by the thermal‐unit growth coefficient. The growth data also showed that the widely used specific growth rate was not an appropriate model. Fish fed at the lowest feeding level (25%), which represented a maintenance ration (energy gain was less than 2 kJ fish^?1 day^?1), showed positive protein deposition but negative lipid deposition. This indicates that fish fed a maintenance ration mobilize body lipid reserve to support protein deposition. The efficiency of energy for growth (k_g) was estimated to be 0.63. The factorial multiple regression approach estimated that the partial efficiencies of metabolizable energy utilization for protein deposition (k_p) and lipid deposition (k_f) were 0.63 and 0.72, and that maintenance energy requirement was about 19 kJ (kg BW^0.824)^?1, for rainbow trout held at 8.5°C.     

Cloning and expression of a surface immunogenic protein in Streptococcus dysgalactiae isolated from fish and its application in enzyme‐linked immunosorbent assays to diagnose S. dysgalactiae infections in fish

Lancefield group C Streptococcus dysgalactiae (GCSD) causes severe necrotic lesions in the caudal peduncle in the genus Seriola farmed in Japan. To develop a sero‐diagnostic method for GCSD infection in farmed fish, we attempted to identify a surface immunogenic protein that induces an antibody after infection with GCSD by immunoblot analysis using sera collected from infected fish. A protein obtained from sodium dodecyl sulfate (SDS) extracts of GCSD was identified as S. dysgalactiae surface immunogenic protein (Sd‐Sip). Sd‐Sip exhibited more than 94% homology with a surface antigen or a hypothetical protein from S. dysgalactiae mammalian isolates at the nucleotide sequence level. Expression of the recombinant Sd‐Sip (rSd‐Sip) was confirmed by immunoblot analysis, that is, its reactivity to GCSD‐infected sera. Antibody detection ELISA using rSd‐Sip and their usefulness for diagnosis of GCSD infection were examined. GCSD‐infected sera collected from farmed amberjack, Seriola dumerili (Risso), showed strong reaction with immobilized rSd‐Sip. Meanwhile, sera immunized by other pathogenic bacteria of fish were showed ELISA values similar to those of non‐infected sera. These results of this study suggest that the antibody detection ELISA using rSd‐Sip is an effective diagnostic method for GCSD infection in fish.