铜在西施舌鳃和消化腺蓄积及对SOD和CAT活性影响

为了研究重金属铜(Cu2+)在西施舌鳃、消化腺组织中的蓄积规律及其对超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性的影响,本文采用急性毒性实验的方法,将西施舌置于不同浓度Cu2+溶液进行实验。结果显示,鳃组织中的Cu2+在第4天时达最大蓄积量,为79.7μg/g,消化腺组织则在第8天蓄积量达最大,为139.2μg/g,Cu2+的最大蓄积均出现在0.16 mg/L胁迫组,消化腺Cu2+浓度蓄积均随胁迫浓度的增加而升高;鳃、消化腺组织CAT活性均呈先升高后降低趋势,且后者CAT活性显著高于前者;鳃组织SOD活性呈先升高后降低趋势,且受到显著诱导(P0.05),消化腺组织的SOD活性则呈下降趋势,在0.16 mg/L胁迫组,鳃和消化腺组织的SOD活性均分别在第3~4天受到极显著抑制(P0.01),表明CAT和SOD活性可作为指示西施舌受Cu2+污染程度的重要指标。     

花鲈鳃与鳔器官发育的组织学与形态学观察

为阐明花鲈鳃与鳔器官的发生机制,实验采用连续组织切片技术接合形态学观察对出膜后1～45 d花鲈胚后发育的鳃与鳔器官的发生、发育过程进行了系统的观察与研究。结果显示,花鲈仔稚鱼鳃的胚后发育分为4个阶段,鳃原基出现期(0～3 d)、鳃丝分化期(4～14 d)、鳃小片分化期(15～25 d)与鳃器官完善期(26～45 d)。在水温15～18°C条件下,花鲈孵化后的第1天,鳃原基出现;孵化后的第15天,仔鱼假鳃上分化出鳃小片结构;孵化后的第25天,仔鱼各鳃弓上均分化出鳃小片结构;孵化后的第45天,稚鱼鳃结构发育完全,与成鱼相同。组织学观察结果显示,花鲈鳔器官的发育时期分为形成、扩张、充气和退化4个阶段。花鲈初孵仔鱼未出现鳔原基,在孵化1 d后,仔鱼出现鳔原基,5 d后仔鱼鳔开始扩张,11 d后仔鱼鳔充气完成,13 d后仔鱼鳔开始退化。     

低氧胁迫对鲻幼鱼生长、能量代谢和氧化应激的影响

为研究低氧胁迫对鲻幼鱼生长、能量代谢和氧化应激的影响,实验将其放在溶解氧(DO,mean±SE)含量分别控制在(1.66±0.41)、(4.35±0.53)、(7.03±0.36)mg/L的条件下养殖10 d,然后恢复至接近饱和溶解氧含量7.0 mg/L的条件下养殖30 d,研究其特定生长率、排氨率、耗氧率、氧氮比和血浆、肌肉、肝脏及鳃组织的总抗氧化能力(T-AOC)、过氧化物歧化酶(SOD)活力、抗超氧阴离子活力(ASOR)、丙二醛(MDA)含量、乳酸(LD)含量、总谷胱甘肽(T-GSH)、还原型谷胱甘肽(GSH)和氧化型谷胱甘肽(GSSG)含量。结果表明:低氧胁迫对鲻幼鱼的生长、能量代谢影响显著,较严重缺氧组鲻的体质量、特定生长率(SGR)、耗氧率和排氨率显著低于其他处理,不具有补偿生长的能力;而轻微缺氧组获得完全补偿生长。低氧胁迫对鲻氧化应激指标影响显著,胁迫结束时鲻通过提高某些抗氧化酶的活力来增强抗氧化能力,以提高其应对恢复正常溶解氧环境可能带来的氧化应激的能力,同时在恢复溶氧后鲻氧化应激反应也较强烈。在恢复溶解氧阶段,肝脏中GSH显著增加,说明鲻体内的保护机制被激活。肝脏和鳃中MDA的含量在低氧胁迫后与溶解氧含量呈明显的负相关性,在复氧30 d后仍然高于对照组,表明低氧胁迫加强鲻肝脏和鳃组织脂质过氧化反应。     

悬沙胁迫下熊本牡蛎的损伤及恢复

首先将熊本牡蛎(Crassostrea sikamea)暴露于不同质量浓度(0、50、100、500、1000和5000 mg/L)悬沙中15d后,再将受试牡蛎转移到干净海水中恢复培养15 d,观察牡蛎的存活率,检测鳃丝中Na+-K+-ATP酶、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性变化、鳃细胞DNA损伤情况和肌肉中RNA/DNA比率变化,探讨悬沙对牡蛎的影响。结果表明,悬沙暴露试验后,本研究所设悬沙浓度对牡蛎存活率几乎无影响,但当悬沙质量浓度≥500mg/L时,鳃丝中Na+-K+-ATP酶、SOD和CAT活性开始显著降低,鳃细胞中开始检测到明显的DNA损伤,反映牡蛎生长状况的RNA/DNA比率也较对照组明显减小(P<0.05)。这些受损牡蛎经干净海水培养15 d后,检测的生理生化指标虽有一定程度的恢复,但仍未恢复到对照组和低浓度悬沙组的水平。可见,较高水平的悬沙胁迫对牡蛎并没有产生致命的影响,依据常规的生态毒理学指标如存活率并不能得出有效的评价结果,但分子细胞水平上的各指标就能比较灵敏地反映悬沙胁迫的影响。     

扑草净对四角蛤蜊抗氧化酶活性及组织细胞的影响

为探讨扑草净胁迫对四角蛤蜊(Mactra veneriformis)的毒性效应, 开展了不同质量浓度扑草净(0.2 μg/L、 1.0 μg/L、10 μg/L)对四角蛤蜊 21 d 胁迫及 15 d 净水释放实验, 测定不同时间点鳃、消化腺中超氧化物歧化酶 (superoxidedismutase, SOD)、过氧化氢酶(catalase, CAT)和谷胱甘肽过氧化物酶(glutathione peroxidase, GPx)等抗氧化酶活性, 观察鳃组织细胞形态学变化。结果表明, 扑草净对四角蛤蜊 SOD、CAT、GPx 均有一定的诱导或抑制, 0.2 μg/L 对其氧化胁迫小于其他两组; 净水释放阶段 1.0 μg/L、10.0 μg/L 组酶活性不能完全恢复甚至活性丧失, 10.0 μg/L 扑草净对四角蛤蜊有不可逆氧化损伤。扑草净可引起鳃上皮细胞萎缩、纤毛脱落, 鳃丝内腔隙变大。随着扑草净浓度增高或胁迫时间延长, SOD、CAT 及鳃组织细胞形态变化存在明显浓度–效应和时间–效应, 高浓度扑草净对四角蛤蜊有明显毒性效应。结论认为, 四角蛤蜊鳃中 GPx 可作为扑草净污染的潜在生物标志物, 为海洋生态环境污染做出预警。     

菲和苯并（b）荧蒽曝露对翡翠贻贝外套膜的氧化胁迫及损伤

实验室条件下研究了不同质量浓度（2.0μg.L-1、10.0μg.L-1和50.0μg.L-1）的菲（PHE）和苯并（b）荧蒽（BbF）胁迫15 d和清洁海水恢复7 d中翡翠贻贝（Perna viridis）外套膜组织中超氧化物歧化酶（SOD）活力和丙二醛（MDA）质量摩尔浓度的变化。结果表明,PHE胁迫下翡翠贻贝外套膜SOD活力呈先升高后降低的变化规律;BbF胁迫下的翡翠贻贝外套膜SOD活力在胁迫第15天时被显著诱导（P〈0.05）。从b（MDA）的变化来看,PHE和BbF均可导致翡翠贻贝外套膜明显的氧化损伤,之后在清洁海水的净化过程中,这种损伤逐渐降低并恢复至正常水平。鉴于2种PAHs胁迫下翡翠贻贝外套膜SOD活力和b（MDA）均发生明显变化并表现出一定的差异性,翡翠贻贝体内的生化指标适合指示PAHs对海洋环境的污染。     

锐钛型纳米二氧化钛对河蚬氧化应激的影响

为评价纳米二氧化钛（TiO2-NPs）对河蚬（Corbicula fluminea）的毒性效应,采用5、50、100 mg/L浓度锐钛型TiO2-NPs对河蚬暴露处理24 h、48 h、96 h和192 h,测定其鳃、消化腺和斧足肌肉组织中钛含量以及谷胱甘肽S转移酶（GST）、超氧化物歧化酶（SOD）的活性。结果表明：（1）在相同暴露时间下,河蚬3种组织的平均钛含量均显著上升并高于空白对照组（P<0.05）;随暴露时间延长,消化腺和斧足肌肉中平均钛含量总体上呈上升趋势,且消化腺中钛含量高于斧足组织,而低、中浓度组鳃组织平均钛含量处于较稳定水平;暴露24～192 h,鳃、消化腺和斧足肌肉中平均钛含量分别为0.73～3.50、2.88～32.37、1.15～3.11 μg/g;（2）在暴露初期,河蚬3种组织的GST活性不同程度上升;随暴露时间延长,鳃和消化腺中GST活性先显著下降、后上升,斧足肌肉中GST活性呈现逐步下降趋势;暴露24～192 h,鳃、消化腺和斧足肌肉中GST活性分别为97.39～371.44、164.92～837.22、63.39～247.75 U/mg;（3）暴露24 h后,3个浓度组河蚬鳃和斧足肌肉中SOD活性均明显上升,低浓度组消化腺SOD活性也显著上升;随暴露时间延长,3种组织中SOD活性均呈现逐渐下降趋势,且SOD活性下降幅度与处理浓度呈正相关;暴露24～192 h,鳃、消化腺和斧足肌肉中SOD活性分别为7.68～27.05、3.63～16.92、4.25～43.08 U/mg。研究表明,3种浓度TiO2-NPs暴露导致钛在河蚬体内显著富集并引起氧化应激反应,其对河蚬具有明显的毒性效应。     

四氯乙烯和镉联合胁迫对草鱼SOD和POD活性影响

为了考察超氧化物歧化酶(SOD)和过氧化物酶(POD)是否可以作为四氯乙烯(PCE)和镉(Cd2+)联合污染生物指标,采用静水生物测试法,研究了PCE和Cd2+联合胁迫对草鱼(Ctenopharyngodon idellus)肝胰脏、肾脏和鳃组织SOD以及肝胰脏、肾脏POD的影响。结果表明:(1)PCE和Cd2+复合污染胁迫时,草鱼肝胰脏SOD随着时间变化呈现"降低-升高-降低"的变化趋势,且最高浓度组始终低于对照;(2)肾脏SOD在所有暴露浓度组随着时间变化呈现"降低-升高-降低"的变化趋势,除最低浓度组在120 h显著高于对照外,其他均显著低于对照;(3)鳃组织SOD也呈现"降低-升高-降低"的变化趋势,但始终低于对照;(4)高浓度组(1/4TU和1/2TU)草鱼肝胰脏和肾脏POD活性随着暴露时间变化呈"降低-升高-降低"的变化趋势,但肝胰脏和肾脏的POD活性始终显著低于对照(P0.05);(5)草鱼鳃组织SOD活性明显低于肝胰脏和肾脏。PCE和Cd2+分别破坏了酶的蛋白结构和诱导了鱼体细胞膜的脂质过氧化,二者联合污染比单一污染加剧了草鱼的毒性效应。     

0#柴油水溶性成分对黑鲷肝脏、鳃、肌肉组织中抗氧化酶活性的影响

采用室内实验方法,研究了不同浓度(0 mg·L-1、0.015 mg·L-1、0.03 mg·L-1、0.06 mg·L-1)0#柴油水溶性成分(WSF)对黑鲷(Sparus macrocephalus)肝脏、鳃和肌肉谷胱甘肽-S-转移酶(GST)、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)的影响。结果显示:(1)肝脏、鳃、肌肉和组织中GST活性与0#柴油具有明显的时间-效应和剂量-效应关系,肝脏组织中GST活性较肌肉和鳃组织中的更为灵敏;(2)各组织中SOD活性随时间和剂量的变化整体无明显规律;(3)肝脏组织中CAT活性先诱导后抑制,肌肉中始终被诱导,鳃中始终被抑制。CAT活性变化幅度不如GST明显。实验表明,黑鲷肝脏组织中GST更适合作为0#柴油污染响应的生物标志物,用作早期海洋石油污染的预警和监测的指标之一。     

溶解氧对团头鲂耐低氧新品系F_5代的鳃组织形态及各组织酶活性的影响

为研究不同浓度溶解氧(DO)对团头鲂(Megalobrama amblycephala)耐低氧新品系F5代鳃组织形态以及各组织酶活性的影响,本研究将团头鲂在低氧[DO为(1.7±0.2) mg/L]和高氧[DO为(19.3±0.5) mg/L]条件下分别处理0、4和7 d,恢复常氧[DO为(7.8±0.3) mg/L] 7 d后,通过石蜡切片观察鳃组织的形态,并测定了鳃、肝胰腺、肠道、肌肉中过氧化氢酶(CAT)、琥珀酸脱氢酶(SDH)及乳酸脱氢酶(LDH)活性和丙二醛(MDA)含量。石蜡切片结果显示,随着低氧处理时间的延长,团头鲂新品系鳃丝的层间细胞团体积减小,鳃小片表面积增加,恢复常氧7 d后又有所恢复。高氧条件下,层间细胞团体积增大,鳃小片表面积减小,恢复常氧7 d后也会恢复。酶活性检测结果显示,在低氧和高氧2种条件下,随着处理时间的延长,CAT活性和MDA含量在各组织中的变化无明显规律,但均有显著差异(P0.05)。低氧条件下,LDH活性显著增高,SDH活性显著降低(P0.05)。高氧条件下,LDH活性显著降低,SDH活性显著增高(P0.05)。本研究可为溶解氧对团头鲂的鳃组织以及各组织酶活性的影响提供基础资料,并为团头鲂新品系的养殖与选育奠定基础。     

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.