A new bathymodioline mussel symbiosis at the Juan de Fuca hydrothermal vents

Until recently, the only major hydrothermal vent biogeographic province not known to include bathymodioline mussels was the spreading centers of the northeast Pacific, but deep-sea dives using DSV Alvin on the Endeavor segment of the Juan de Fuca Ridge (47°56N 129°06W; ∼2,200 m depth) in August 1999 yielded the only recorded bathymodioline mytilids from these northeastern Pacific vents. One specimen in good condition was evaluated for its relatedness to other deep-sea bathymodioline mussels and for the occurrence of chemoautotrophic and/or methanotrophic symbionts in the gills. Phylogenetic analyses of the host cytochrome oxidase I gene show this mussel shares evolutionary alliances with hydrothermal vent and cold seep mussels from the genus Bathymodiolus, and is distinct from other known species of deep-sea bathymodiolines, suggesting this mussel is a newly discovered species. Ultrastructural analyses of gill tissue revealed the presence of coccoid bacteria that lacked the intracellular membranes observed in methanotrophic symbionts. The bacteria may be extracellular but poor condition of the fixed tissue complicated conclusions regarding symbiont location. A single gamma-proteobacterial 16S rRNA sequence was amplified from gill tissue and directly sequenced from gill tissue. This sequence clusters with other mussel chemoautotrophic symbiont 16S rRNA sequences, which suggests a chemoautotrophic, rather than methanotrophic, symbiosis in this mussel. Stable carbon (δ¹³C = −26.6%) and nitrogen (δ¹⁵N = +5.19%) isotope ratios were also consistent with those reported for other chemoautotroph-mussel symbioses. Despite the apparent rarity of these mussels at the Juan de Fuca vent sites, this finding extends the range of the bathymodioline mussels to all hydrothermal vent biogeographic provinces studied to date.     

Cytoenzymatic investigation of intracellular digestion in the symbiont-bearing hydrothermal bivalve <Emphasis Type="Italic">Bathymodiolus azoricus</Emphasis>

Invertebrates harbouring endosymbiotic chemoautotrophic bacteria are widely distributed in a variety of reducing marine habitats, including deep-sea hydrothermal vents. Bathymodiolids are dominants of the biomass at geochemically distinct vent sites of the Mid Atlantic Ridge (MAR) and thus are good candidates to study biological processes in response to site-specific conditions. To satisfy their nutritional requirements, these organisms depend to varying extent on two types of chemoautotrophic symbionts and on filterfeeding. The quantitative relationships of the nutritional modes are poorly understood. Using enzyme cytochemistry, electron microscopy and X-ray microanalysis, the structural and functional aspects of the cellular equipment necessary for lysosomal digestion was studied. We provide evidence for the following: (1) the basis of intracellular digestion of symbionts in Bathymodiolus azoricus from two geochemically distinct vent sites was not mainly in the large lysosomal bodies as previously thought (based on the membranous content resembling bacteria); (2) senescent bacteria are autolysed, possibly by bacterial acid phosphatase, that is more likely a cell cycling of the symbionts rather than an active lysosomal digestion by the host; (3) the consistent absence of hydrolases may indicate the improper use of the name “lysosome” for large vesicles at the base of the gill bacteriocytes (4) nutrient transfer in B. azoricus, therefore, may more likely be accomplished through leaking of metabolites from the symbiont to the host, not excluding lysosomal resorption of dead bacteria as an auxiliary strategy for organic molecule transfer; (5) evidence is provided for microvillar transfer of substances from the seawater that may indicate filter-feeding, in non-symbiotic ciliated gill cells of mussels from Lucky Strike; (6) two types of lysosomal vesicles can be distinguished in digestive cells based on their enzymatic content and their elemental composition.     

Ultrastructural,biochemical, and immunological characterization of two populations of the mytilid mussel <Emphasis Type="Italic">Bathymodiolus</Emphasis><Emphasis Type="Italic">azoricus</Emphasis> from the Mid-Atlantic Ridge: evidence for a dual symbiosis

A recently described species of mytilid mussel, Bathymodiolus azoricus Von Cosel et al., 1999, was observed to be the dominant organism at the hydrothermal vents off the Azores, at both the Lucky Strike and Menez Gwen sites. Evidence suggests this species of Bathymodiolus represents yet another example of the intriguing dual symbiosis known in three other species of deep-sea mytilid mussels. Transmission electron micrographs (TEM) show the majority of gill bacteriocytes in mussels sampled from both populations to contain two distinct symbiont morphotypes. One morphotype is characterized by large size (mean diameter, 1.25 µm), coccoid shape, and stacked intracytoplasmic membranes that are consistent with the morphology of type I methanotrophs. The second morphotype is smaller (mean diameter, 0.35 µm) and was observed in coccoid or rod shapes. Immunoblots revealed the presence of ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) and methanol dehydrogenase (MeDH) in both populations of mussels. Activities of these enzymes, as well as sulfate adenylyl transferase (ATP sulfurylase) and adenylyl sulfate reductase (APS reductase), were detected in gill extracts. The activities measured for the two populations were highly variable, though the population sampled from Lucky Strike showed higher RubisCO activity. Stable carbon isotope values (Lucky Strike, '¹³C=-32.6ǂ.3‰; Menez Gwen, '¹³C=-22.8ǂ.4‰) are in the range of previously reported stable carbon isotope measurements for mytilid mussels hosting a dual symbiosis. Collectively, these results provide evidence for the activity of both sulfur-oxidizing and methane-oxidizing metabolic pathways in B. azoricus. Furthermore, evidence for a greater dependence on methanotrophy in the Menez Gwen mussel population is offered by analysis of cell counts from TEMs. Higher methanotroph numbers, and putatively activity, in this population of mussels are further supported by published geochemical data indicating higher methane concentrations in the vent fluids at Menez Gwen. This finding suggests that environmental conditions may regulate a balance between the physiological activities of different symbiont populations associated with these mussels. The existence of a dual symbiosis could thus confer greater environmental tolerance and increased niche space to the mytilid host in the stochastic hydrothermal vent habitat.     

Morphological adaptations to chronic hypoxia in deep-sea decapod crustaceans from hydrothermal vents and cold seeps

Animals inhabiting hydrothermal vents and cold seeps face conditions that are challenging for survival. In particular, these two habitats are characterized by chronic hypoxia, sometimes reaching complete anoxia. The characteristics of the scaphognathite and gills were studied in four species of shrimp and three species of crabs from hydrothermal vents and cold seeps, in order to highlight potential adaptations that could enhance oxygen acquisition in comparison with shallow-water relatives. All the vent and seep species studied here exhibit significantly larger scaphognathites, likely allowing more water to flow over their gills per stroke of this appendage. This is probably more energetically efficient that prolonged hyperventilation. In contrast to annelids, vent and seep decapods usually do not possess enlarged gills, a phenomenon likely due to the physical limitations imposed by the size of the gill chamber. In the vent shrimp Rimicaris exoculata and the vent crab Bythograea thermydron, however, there is a significantly higher specific gill surface area linked to a higher number of lamellae per gram of gill. Again in contrast to annelids, the diffusion distance through the gills is not strikingly different between the vent shrimp Alvinocaris komaii and the shallow-water species Palaemon spp. This may indicate that the epithelium and cuticle of the decapod gills are already optimized for oxygen uptake and that reducing the thickness of these compartments is not physically possible without affecting the physical integrity of the gills.     

Evolution of habitat use by deep-sea mussels

Previous phylogenetic studies proposed that symbiont-bearing mussels of the subfamily Bathymodiolinae (Bivalvia: Mytilidae) invaded progressively deeper marine environments and evolved from lineages that decomposed wood and bone to specialized lineages that invaded cold-water hydrocarbon seeps and finally deep-sea hydrothermal vents. To assess the validity of the hypotheses, we examined two nuclear (18S and 28S rRNA) and two mitochondrial genes (COI and ND4) from a broad array of bathymodiolin species that included several recently discovered species from shallow hydrothermal seamounts. Bayesian phylogenetic analysis and maximum-likelihood estimates of ancestral character states revealed that vent species evolved multiple times, and that reversals in vent and seep habitat use occurred within the sampled taxa. Previous hypotheses regarding evolution from wood/bone-to-seeps/vents are supported in that mid-ocean hydrothermal vent species may represent a monophyletic group with one noticeable reversal. Earlier hypotheses about progressive evolution from shallow-to-deep habitats appear to hold with a few instances of habitat reversals.     

Transparent exopolymer particles in a deep-sea hydrothermal system: Guaymas Basin,Gulf of California

This is the first report of transparent exopolymer particle (TEP) concentrations within deep-sea hydrothermal vent systems using colorimetric methods, measuring TEP in supernatants of sediments surrounding the vents, in fluids emanating directly from hydrothermal vents and in neutrally buoyant hydrothermal plumes. Samples were collected at Guaymas Basin (Gulf of California), a sedimented hydrothermal system. TEP concentrations within the hydrothermal fluids were significantly greater than the only other report of TEP in deep water. The range of values for TEP abundance were 8–6,451 μg/L of gum xanthan equivalents, the highest values being associated with supernatants of microbial mat-covered sediments. The potential sources and significance of the high concentrations of TEP observed in this deep-sea hydrothermal environment are discussed.     

Effect of ambient oxygen concentration on activities of enzymatic antioxidant defences and aerobic metabolism in the hydrothermal vent worm, Paralvinella grasslei

The alvinellid Paralvinella grasslei is a common endemic polychaete from the deep-sea hydrothermal vent communities located on the East Pacific Rise (EPR). These organisms colonise a large range of microhabitats around active sites where physico-chemical conditions are thought to generate reactive oxygen species (ROS). Furthermore, in this aerobic organism, ROS could also be generated by the activity of the mitochondrial respiratory chain. In this paper, we investigated the effect of ambient oxygen concentration on the activities of three essential antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT; glutathione peroxidase, GPX) and their relationships with the activity of enzymes involved in aerobic metabolism (cytochrome c oxidase, COX; citrate synthase, CS). Results of incubation of P. grasslei in a high-pressure vessel with circulating seawater at different oxygen partial pressures indicate that this worm regulates COX and CS activities differently in gills and body wall. CAT and GPX activities increase in these tissues when animals are maintained in filtered surface seawater. Moreover, levels of malondialdehyde increase in gills, testifying that oxidative damage occurs under these conditions. CAT and GPX activities are positively related to COX and CS activities, but no correlation was detected between SOD and the metabolic enzyme activities. In comparison with littoral annelids, SOD activities are very high whereas CAT activities are very low or absent in P. grasslei. The possible reasons for the occurrence of such differences are discussed.     

重质原油和轻质原油水溶性组分对紫贻贝(Mytilus edulis)毒理效应的研究

近年来,海洋石油开采与运输泄漏、石油及产品离岸排放等事故逐年增多,对近海海域生态环境产生了巨大破坏。为探究重质原油和轻质原油对紫贻贝(Mytilus edulis)毒理效应,测定了不同浓度重质原油和轻质原油暴露下紫贻贝鳃和外套膜中过氧化氢酶(CAT)和超氧化物歧化酶(SOD)的活性及体内石油烃的含量变化。结果显示,石油污染暴露下,紫贻贝腮和外套膜中CAT和SOD活性变化明显,与暴露浓度和暴露时间有关。CAT活性在轻质原油组随着浓度的增大,呈现下降趋势,且随着暴露时间的延长呈现先下降后上升趋势;在重质原油暴露组,随着浓度的增大,呈现先上升后下降趋势,且随着暴露时间的延长呈现先下降后上升趋势。SOD活性在轻质原油与重质原油暴露组,随着浓度的增大,呈现下降趋势,且随着暴露时间的延长呈现上升趋势并存在一定的剂量-效应关系。重质原油和轻质原油暴露168 h后紫贻贝体内总石油烃含量呈线性递增,生物富集系数(BCF)随着暴露浓度的增加不断减小并最终趋于平稳。结果表明,以紫贻贝腮和外套膜中SOD和CAT活性作为石油烃污染的生物标志物具有一定应用前景,紫贻贝对原油溶液中石油烃的生物富集作用可用来判断污染原油的来源和性质。     

镉和铅对菲律宾蛤仔脂质过氧化及抗氧化酶活性的影响

为了研究亚致死浓度的重金属对海洋贝类的毒性效应,探讨其可能的作用机理,在实验生态条件下以菲律宾蛤仔(Ru-ditapes philip pinarum)为目标生物,采用半静态毒性实验方法,研究了不同浓度Cd2+(0.0948、0.237和0.474mg·L-1)和Pb2+(0.276、0.690和1.380mg·L-1)对菲律宾蛤仔鳃和消化腺组织中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性以及丙二醛(MDA)含量的影响。结果显示:(1)鳃和消化腺中的抗氧化酶及MDA的变化呈现出类似的趋势,在胁迫初期,各浓度处理组菲律宾蛤仔鳃和消化腺组织SOD和CAT与对照组相比活性都显著升高(P<0.01),呈现出明显的诱导效应,而MDA含量与对照组相比差异不显著(P>0.05);随着胁迫时间的延长,高浓度Cd2+(0.474mg·L-1)和Pb2+(1.380mg·L-1)处理组中SOD、CAT活性快速下降,与对照组相比差异显著;低浓度处理组中的抗氧化活性虽然也较对照组有所下降,但总体下降幅度不如高浓度组明显,并且所历暴露时间较长。各浓度处理组中MDA含量变化一致,均呈现出先升高后降低的趋势,且含量均高于对照组。(2)通过相关性分析,菲律宾蛤仔消化腺组织中的SOD活性与Cd2+浓度的相关性大于鳃组织,与Pb2+浓度的相关性则小于鳃组织;消化腺组织中的CAT活性与Cd2+、Pb2+浓度呈抛物线型相关,与鳃组织CAT活性相关性不十分显著。这说明消化腺组织中SOD活性对Cd2+的敏感性大于鳃组织,消化腺组织中CAT活性对Cd2+、Pb2+的敏感性大于鳃组织。因此,菲律宾蛤仔消化腺中SOD、CAT对水环境中的重金属反应敏感,且存在一定的剂量-效应关系,消化腺组织中SOD和CAT活性与其他敏感性指标一起可以作为指示早期海洋重金属污染的生物标志物。     

Investigation of metallothionein level,reduced GSH level,MDA level,and metal content in two different tissues of freshwater mussels from Atatürk Dam Lake coast,Turkey

Atatürk Dam Lake is one of the important freshwater ecosystems in the world in terms of the size of the surface area and the biodiversity. The objective of this study was to determine the effects of metal pollution in the Atatürk Dam Lake on some biochemical markers in the gills and digestive glands of mussels (Unio mancus). Mussel samples were collected in July-2018 from four stations. The metal residues (Cd, Cu, Pb, Zn, and Ni) in the tissues were determined by ICP-MS. The MT, reduced GSH, and MDA levels were analysed using the proposed spectrophotometric methods. According to the results, toxic metals such as Cd and Pb in both tissues were determined mostly in mussels collected from St1. The highest MT and MDA levels in the gills were determined in St3 and St2 respectively, while the highest MT and MDA levels in the digestive glands were determined in St1. Although there was no significant difference in the reduced GSH level in the gills among the stations, the highest reduced GSH level in the digestive glands was determined in St4. These results indicated that mussels are appropriate sentinel organisms for metal contamination with effects on oxidative stress and metal exposure biomarkers.     

Mantle-to-shell CaCO<Subscript>3</Subscript> transfer during shell repair at different hydrostatic pressures in the deep-sea vent mussel <Emphasis Type="Italic">Bathymodiolus azoricus</Emphasis> (Bivalvia: Mytilidae)

Calcium carbonate transfer was experimentally examined in hydrothermal mussels Bathymodiolus azoricus, which were collected from 850 m depth at Menez Gwen hydrothermal vent site (31°31′W, 37°50′N) on the Mid Atlantic Ridge in May 2007. In each of four 10-day experiments, groups of mussels were maintained at atmospheric pressure or re-pressurised to depths relevant to their site of occurrence, i.e. 850 m depth at Menez Gwen, 1,750 m at Lucky Strike (31°31′W, 37°18′N) and 2,300 m at Rainbow (31°31′W, 36°13′N). The shells of experimental mussels were perforated and mantle tissue was fixed for light and TEM studies at days 7 and 10 following the injury. Simultaneously, haemocytes from the extrapallial fluid (EPF) at the site of induction were studied. At day 7 the response was most intense in the middle fold of the mantle margin and possibly proportional to hydrostatic pressure. At day 10 the epithelial cells on the mantle surface facing the body cavity produced copious organic secretions that avidly bound calcium. Haemocyte migration was noted within the mantle tissue, and the haemocytes at the mantle surface facing the shell had a Ca-positive granular content. Large haemocytes were detected in the EPF at the injury site, and some showed evidence of an immune reaction while others showed Ca-positive granular content. These results suggest that haemocytes are involved in shell repair in these deep-sea mussels just as in some freshwater and shallow marine molluscs.     

典型重金属胁迫对日本沼虾的氧化损伤及交互作用

为深入探讨水体不同浓度重金属联合暴露对水生生物的慢性毒性机理，本研究以日本沼虾(Macrobranchium nipponense)为受试生物，镉(Cd)和铅(Pb)为目标金属，超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、金属硫蛋白(MT)和丙二醛(MDA)为测试终点，研究不同浓度的Cd和Pb单一及联合暴露对日本沼虾的氧化损伤及交互作用。实验结果表明：Cd对虾的致死浓度为1 mg?L-1，当其与同浓度Pb联合时，致死毒性增强；在0.01 mg?L-1和0.1 mg?L-1下联合时均表现为拮抗作用。不同处理组对标志物产生不同程度的诱导或抑制效应，其中，SOD活性均受到胁迫抑制，0.1 mg?L-1Cd暴露10 d后对肝胰腺SOD抑制率达53.38%，0.1 mg?L-1Pb暴露10 d后对肌肉SOD抑制率达70.02%；CAT活性整体受胁迫激活，肝胰腺与肌肉CAT活性在时间尺度上呈现相反的变化规律；肝胰腺中MT和MDA对重金属的敏感性要高于肌肉；综合生物标志物响应(IBR)评价表明，机体在时间尺度上可通过酶活性调节而具有一定的解毒功能，但并不能消除重金属引起的氧化损伤，且重金属单一毒性要高于联合毒性，其中Cd对肝胰腺毒性最大，Pb对肌肉毒性最大。研究结果能够为水体重金属生态风险预警、水质基准制定及流域水环境管理提供依据。? 关键词：日本沼虾；重金属；氧化损伤；交互作用；分子标志物     

麝香酮和镉单一与复合污染对金鱼藻的生态毒理效应研究

为从生物化学角度探讨一种新型污染物———麝香酮与镉(Cd)单一和复合污染的生态毒理效应,以金鱼藻(Ceratophyllum demersum L.)为研究对象,分析了不同浓度麝香酮和Cd在水中单一与复合污染对金鱼藻叶片中抗氧化系统酶,包括超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT),脂质过氧化最终产物丙二醛(MDA),可溶性蛋白(SP)和叶绿素含量的影响.结果表明:在单一麝香酮和Cd暴露下,SOD活性第1天均显著降低,而第7天在低浓度污染物的胁迫下呈升高趋势;金鱼藻受麝香酮和Cd胁迫的第1天,POD酶活性分别呈升高和降低趋势;麝香酮浓度为0.05mg·L-1或Cd浓度为0.01mg·L-1时,金鱼藻叶片中的CAT活性变化表现为显著的毒物兴奋作用;用两种污染物单一或复合处理第7天,金鱼藻叶片中的MDA和叶绿素含量可以作为评价麝香酮或/和Cd污染水体环境的敏感指标;SP在这两种污染物胁迫下处于能量及脂蛋白的补偿和应激蛋白的合成两方面的得失平衡过程中,故其含量与处理浓度之间无显著相关关系;复合污染中低浓度的麝香酮和Cd复合对金鱼藻表现为拮抗作用,高浓度的复合表现为相加或协同作用.     

贵州省典型矿区土壤重金属污染对蚯蚓的毒性效应评估

选取我国贵州省某矿区典型的重金属复合污染土壤开展28 d慢性毒性暴露试验,以蚯蚓体内2种抗氧化酶活性——过氧化氢酶(CAT)和超氧化物歧化酶(SOD)、8-羟基脱氧鸟苷(8-ODHG)和金属硫蛋白(MT)含量为生物指标,评估了以上生物指标与土壤重金属含量的相关性,探讨该研究方法用于矿区土壤重金属生态风险评估的可行性。结果表明,CAT和SOD在暴露周期内均出现先诱导后抑制的动态响应过程,表明蚯蚓通过提高CAT和SOD的活性来清除机体因污染胁迫而产生的自由基,以适应环境变化,在毒性缓解后,蚯蚓体内代谢产物的积累抑制了抗氧化氢酶活性,CAT和SOD活性下降并趋于稳定。暴露于重金属污染亚致死浓度时,蚯蚓体内的8-OHDG含量随着暴露时间的延长显著降低,随着暴露浓度的增加,损伤存在由低到高的转变。在28 d暴露周期内,蚯蚓体内MT在重金属胁迫下发挥了解毒作用,MT含量在蚯蚓暴露后第7天增加,随后逐渐降低。本文基于生物毒性试验综合评估了矿区典型重金属污染土壤的生态风险,研究结果对指导重金属复合污染土壤的修复与再利用具有重要意义。     

典型重金属胁迫对日本沼虾的氧化损伤及交互作用

为深入探讨水体不同浓度重金属联合对水生生物的慢性毒性机制,本研究以日本沼虾(Macrobranchium nipponense)为受试生物,镉(Cd)和铅(Pb)为目标金属,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、金属硫蛋白(MT)和丙二醛(MDA)为测试终点,研究不同浓度的Cd和Pb单一及联合暴露对日本沼虾的氧化损伤及交互作用。实验结果表明:Cd对虾的致死浓度为1 mg·L-1,当其与同浓度Pb联合时,致死毒性增强;在0.01 mg·L-1和0.1 mg·L-1下联合时均表现为拮抗作用。不同处理组对标志物产生不同程度的诱导或抑制效应,其中,SOD活性均受到胁迫抑制,0.1 mg·L-1Cd暴露10 d后对肝胰腺SOD抑制率达53.38%,0.1 mg·L-1Pb暴露10 d后对肌肉SOD抑制率达70.02%;CAT活性整体受胁迫激活,肝胰腺与肌肉CAT活性在时间尺度上呈现相反的变化规律;肝胰腺中MT和MDA对重金属的敏感性要高于肌肉;综合生物标志物响应(IBR)评价表明,机体在时间尺度上可通过酶活性调节而具有一定的解毒功能,但并不能消除重金属引起的氧化损伤,且重金属单一毒性要高于联合毒性,其中Cd对肝胰腺毒性最大,Pb对肌肉毒性最大。研究结果能够为水体重金属生态风险预警、水质基准制定及流域水环境管理提供依据。     

纳米氧化镍颗粒对长牡蛎(Crassostreagigas)抗氧化防御体系的影响

纳米氧化镍(nNiO)作为一种广泛使用的纳米颗粒,其水生毒理效应研究还很有限。为探索n Ni O对海洋贝类的毒性机制,本研究将长牡蛎(Crassostrea gigas)置于不同浓度(0、1、10、100 mg·L~(-1))的n Ni O中暴露96 h,分别测定鳃和消化腺组织的丙二醛(MDA)含量和超氧化物歧化酶(SOD)、过氧化物酶(POD)以及过氧化氢酶(CAT)活性,并通过实时荧光定量PCR技术测定了鳃和消化腺中应激蛋白HSP70和AOX基因的表达变化。结果显示:在100 mg·L~(-1)n Ni O处理下,2种组织中MDA含量均显著性升高(P0.01),显示纳米颗粒造成了长牡蛎的脂质过氧化,并可能引起相应的氧化损伤。同时,n Ni O暴露也诱导了长牡蛎抗氧化酶(SOD、CAT和POD)活性的改变。其中,SOD和CAT活性在10 mg·L~(-1)浓度处理组达到最高,而POD活性在1 mg·L~(-1)浓度组即达最高值。在高浓度n Ni O(100 mg·L~(-1))胁迫下,3种抗氧化酶的活性均比低浓度(1和10 mg·L~(-1))处理组降低,表明抗氧化酶的保护作用在较低浓度暴露下更有效;而热激蛋白(hsp70)和交替氧化酶(aox)基因却分别在长牡蛎消化腺和鳃组织中上调表达(P0.01),并表现出一定的组织差异。说明高浓度纳米颗粒暴露中主要是应激蛋白发挥了作用。本文结果为纳米氧化镍对海洋双壳贝类的毒性机制研究及生态风险评估提供了基础数据。     

Elemental concentrations of hydrothermal vent organisms from the Galápagos Rift

Concentrations of 40 elements were determined in tissues and whole bodies of mussels (Bathymodiolus thermophilus) and/or whole bodies of limpets (Neomphalus fretterae) collected from the submarine thermal springs on the Galápagos Rift in 1977. Concentrations of Ag, As, Fe, Mn, Mo, Se, Sr, and Zn were comparable or elevated relative to those of intertidal mollusks, which have been utilized as indicators of anthropogenic trace-metal contamination. Both species contained concentrations of some elements (e.g. Ag, As, Fe, Mn, Mo, Se, Zn) which corresponded with the elevated levels of those elements discharged from hydrothermal vents. Many elements were most enriched in the gills and digestive glands of the mussels. Iron:manganese ratios of those tissues were similar to ratios of pelagic and transitional sediments, indicating that metal-rich suspended particulates had been absorbed onto mucous membranes. Comparisons with other benthopelagic organisms were precluded, since the present data represent essentially the only trace-element analyses of deep-sea macroinvertebrates.     

Biomarkers of oxidative stress as indicators of water pollution in Nile tilapia (Oreochromis niloticus) from a water reservoir in Riyadh,Saudi Arabia

Antioxidant enzyme activities of fish (Oreochromis niloticus) were determined in order to assess the status of pollution in the Wadi Namar (WN), near Riyadh, Saudi Arabia. Activities of four antioxidant enzymes as superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), and concentrations of glutathione (GSH) and oxidant malondialdehyde (MDA) were selected as bioindicators. Fish (n = 14) were sampled in the month of April 2013 from WN and a control site (CS). SOD activity was increased by 37.9%, 47%, and 29% in kidney, liver, and heart, respectively, while a significant decrease (36.4%) was observed in gills of O. niloticus from WN as compared to fish from CS. CAT activity was reduced by 51%, 55%, 47%, and 35% in kidney, liver, heart, and gills of O. niloticus from WN. The GST activities in kidney, liver, and heart of O. niloticus from WN were elevated by 34%, 48%, and 32%, respectively. However, significant fall (49%) in gills of fish was noted from WN compared to fish from CS. GSH levels were increased by 44%, 36%, and 38% in kidney, liver, and heart, respectively, but decreased by 30% in gills. MDA levels of O. niloticus were significantly increased in kidney, liver, and heart in fish from WN. Data indicated that WN is polluted mainly by industrial and urban discharge of liquid waste products.     

Effects of cadmium on metallothionein and histology in gills of tilapia (Oreochromis niloticus) at different salinities

The objectives of this study were to evaluate the effects of sublethal cadmium concentrations on the levels of cadmium, metallothionein (MT) and histological changes in gills of East Java strain tilapia (Oreochromis niloticus) at different salinity levels. The levels of cadmium in control gills were not significantly different at 0, 5 and 10 practical salinity unit (PSU). The cadmium concentrations in gills of cadmium-exposed fish were significantly higher at 0 PSU than at 5, 10 and 15 PSU. The MT concentrations in control gills were not significantly different at 0, 5, and 10 PSU. The MT concentrations of cadmium-exposed fish were significantly higher than those in respective control groups at 0, 5 and 10 PSU. Significant gill damage occurred in fish exposed to cadmium at lower salinity. The epithelial lifting was noted at gills of fish exposed to 2.5 mg/L of cadmium at 0 PSU, and telangiectasis was observed at gills exposed to 5 mg/L of cadmium at 0 PSU. The level of gill damage decreased with increasing salinity of media. The increased MT and histological changes in gills of our findings could be a protective response of animals to toxic effect of cadmium.     

硫酸锰废渣浸出液对斑马鱼的毒性及抗氧化酶活性的影响

已有研究表明,堆积在湘西花垣河河岸的硫酸锰废渣含有多种重金属,可能是导致花垣河河水和沉积物重金属污染的主要原因.为了评价硫酸锰废渣的潜在生态风险和对水生动物的毒性,本研究分析了硫酸锰废渣浸出液中的主要重金属成分,用漫出液对斑马鱼进行了急性毒性实验,观察在急性胁迫下斑马鱼的体征变化,测定了斑马鱼在亚致死浓度下的生化指标的...