PCB77和Cd共同暴露诱导的线粒体损伤及其介导的联合毒性效应

本文以人肝癌细胞系SMMC-7721为生物模型,研究并比较了PCB77和Cd~(2+)对SMMC-7721细胞的单一与联合毒性.通过细胞活性检测发现,当Cd~(2+)暴露浓度为20μmol·L-1,PCB77暴露浓度为25μmol·L~(-1),暴露时间为48 h时,两种污染物产生明显的联合毒性.二者共同暴露虽然不影响细胞膜的完整性,但引起了线粒体膜电位下降、膜通透性显著增加,进而诱导细胞凋亡,同时胞内ROS水平升高.结果表明,PCB77和Cd~(2+)的共同暴露可引发联合肝细胞毒性,其毒性机理是线粒体膜电位下降和膜通透性增加,进而引发细胞凋亡.     

亚砷酸钠对酵母细胞抗氧化酶活性和脂质过氧化的影响

以模式生物酿酒酵母为材料,研究亚砷酸钠对细胞生长、抗氧化酶活性、丙二醛(MDA)含量及胞内活性氧(ROS)水平的影响。结果显示,加入亚砷酸钠(终浓度0.1~0.6 mmol·L~(-1))后,培养液在600 nm处的光密度值(OD600值)低于对照组,并呈浓度依赖性降低。经亚砷酸钠处理12 h后,酵母细胞中过氧化物酶(POD)、过氧化氢酶(CAT)、超氧化物歧化酶(SOD)和总抗氧化能力(T-AOC)活性均增高,但胞内ROS水平和MDA含量与对照组无显著差异。砷处理24 h后,POD在0.2 mmol·L~(-1)砷处理组中活性最高,而CAT、SOD和T-AOC活性呈浓度依赖性增高;胞内ROS水平和MDA含量在高浓度砷组(0.4和0.6 mmol·L~(-1))显著增高。结果表明,亚砷酸钠可抑制酵母细胞生长,改变细胞内抗氧化酶活性,较高浓度时可引起细胞氧化损伤。     

BDE47对Neuro-2a细胞毒性效应及作用机制

探讨2,2',4,4'-四溴联苯醚(2,2',4,4'-tetrabromodiphenylether,BDE 47)对神经细胞Neuro-2a的毒性影响及机制。将Neuro-2a细胞暴露于浓度为6.25、12.5、25、50、100μmol·L-1的BDE 47,采用MTT法检测细胞存活率、荧光探针DCFH-DA检测细胞活性氧生成量、吖啶橙检测溶酶体膜通透性、罗丹明123检测细胞线粒体膜电位、Annexin V-FITC检测细胞凋亡、Western blot检测组织蛋白酶B(Cathespin B)表达。结果显示,与对照组相比,12.5、25、50、100μmol·L~(-1)BDE 47显著降低Neuro-2a细胞存活率和细胞线粒体膜电位(P0.05);6.25、12.5、25、50、100μmol·L~(-1)BDE 47显著诱导活性氧含量升高(P0.05),增加Neuro-2a细胞溶酶体膜通透性(P0.05),诱导Neuro-2a细胞凋亡(P0.05),升高Cathespin B蛋白表达(P0.05)。结果表明,BDE 47可能通过介导溶酶体-活性氧-线粒体环路,诱导Neuro-2a细胞凋亡。     

草酸对珊瑚砂的溶蚀作用及其机制研究

营造热带吹填陆域的宜居生态环境,构建植被生态系统必不可少,其中,研究植被分泌小分子有机酸对岛礁母质珊瑚砂的风化作用对于岛礁生态建设至关重要。通过研究不同浓度草酸对珊瑚砂的溶蚀动力学,建立动力学模型,研究珊瑚砂溶蚀的主要影响因素,探讨草酸对珊瑚砂的溶蚀机制。结果表明,在不同草酸溶液中,反应初始阶段珊瑚砂中Ca~(2+)、Mg~(2+)迅速溶出,随后大量Ca~(2+)被草酸固定生成草酸钙沉淀。随着草酸浓度的增加,溶液中Ca~(2+)浓度逐渐降低,Mg~(2+)浓度逐渐升高,c(Ca~(2+))最大值为0.65 mmol·L~(-1),c(Mg~(2+))最大值为2.87 mmol·L~(-1)。通过Mg~(2+)溶出动力学拟合发现其溶出动力学符合Stumm模型,主要受扩散过程的影响。此外,高浓度草酸会抑制珊瑚砂中Ca~(2+)的溶解流失。XRD和SEM分析结果表明,高浓度草酸与珊瑚砂反应生成草酸钙沉淀相互胶连附着在珊瑚砂表面,且溶蚀过程中优先溶蚀珊瑚砂组分中镁方解石,其次是文石和方解石。     

锶暴露对中华大蟾蜍蝌蚪生长发育的影响及其遗传毒性

为探究锶(Sr)对两栖动物的毒性效应,研究了不同浓度(0、0.2、2和20 mmol·L~(-1)) SrCl_2处理对中华大蟾蜍蝌蚪生长发育及遗传毒性的影响。结果表明,0.2 mmol·L~(-1)Sr~(2+)对肝细胞谷胱甘肽S转移酶(GST)和过氧化氢酶(CAT)活性及金属硫蛋白(MT)含量没有显著影响。MT含量在2 mmol·L~(-1)处理组最高,在20 mmol·L~(-1)处理组低于对照组。这表明,Sr~(2+)处理能诱导机体合成MT量的增加,但长时间高浓度处理会导致机体合成MT能力的损害。GST和CAT活性随着Sr~(2+)暴露浓度上升而提高,表明环境中高浓度Sr~(2+)可引起蝌蚪的氧化应激反应。低浓度的Sr~(2+)处理对中华大蟾蜍蝌蚪不产生明显的遗传毒性,并且对生长发育有一定的促进作用;高浓度的Sr~(2+)处理下,蝌蚪红细胞DNA的损伤程度显著增加,蝌蚪的生长发育受到显著抑制。     

活性氧介导砷诱导的蚕豆保卫细胞死亡

采用蚕豆(Vicia fabaL.)表皮条生物法,研究砷的细胞毒性作用机制。结果发现,一定浓度的NaAsO2可使气孔保卫细胞活性降低,部分细胞死亡,细胞死亡率呈浓度依赖性增高;砷处理组保卫细胞内活性氧(reactive oxygen species,ROS)水平升高。抗氧化剂抗坏血酸和过氧化氢酶及Ca2+特异性螯合剂EGTA、Ca2+通道抑制剂LaC13与NaAsO2共同作用时,砷诱发的细胞死亡被显著抑制;MAPK激酶抑制剂PD98059亦能有效阻止NaAsO2诱发的细胞死亡。研究结果表明,砷胁迫引起的胞内ROS合成增加可能通过Ca2+信号途径介导了保卫细胞的死亡过程,MAPK途径参与了砷诱导的细胞死亡。     

金属离子对赤红球菌(Rhodococcus ruber L9)降解芘的影响及其作用机制

实验室从石油污染土壤中筛选得到一株高效芘降解菌,命名为赤红球菌(Rhodococcus ruber L9),分析了不同浓度Fe~(3+)、Ca~(2+)、Cu~(2+)、Mn~(2+)对该菌降解芘效果的影响.结果发现,0.45 mmol·L~(-1) Fe~(3+)对芘的降解率有明显促进作用,6d时芘降解率最高,可达77%,相较于不加金属离子时提升了约30%.进一步研究发现,当Fe~(3+)存在时,芘降解过程中蛋白总量变化、邻苯二酚1,2-双加氧酶(C120)和邻苯二酚2,3-双加氧酶(C230)酶活性的变化与Fe~(3+)和Fe~(2+)在胞内、胞外浓度的变化密切相关,主要原因是Fe~(3+)的存在,能诱导赤红球菌合成更多与芘降解有关的蛋白,且可以作为酶的活性中心提高酶的活性,从而大幅提高芘的降解效率.     

抗坏血酸对铜胁迫下广藿香幼苗生长、铜积累和抗氧化酶活性的影响

通过室内水培试验,研究了外源添加抗坏血酸(Ascorbic acid,As A)对铜(Copper,Cu)胁迫下广藿香(Pogostemon cablin(Blanco)Benth.)幼苗生长、Cu~(2+)积累和抗氧化酶活性的影响.结果显示,与对照相比,10—80μmol·L-1Cu~(2+)降低了广藿香幼苗的苗长、根长、植株生物量和根系耐性指数,且随Cu~(2+)浓度增大抑制作用增强.与Cu~(2+)胁迫相比,外源添加0.10—0.50 mmol·L~(-1)As A提高了广藿香幼苗的苗长、根长、植株生物量、根系耐性指数、根系活力以及SOD、POD、CAT和APX酶活性,降低其根系相对电导率、MDA含量和Cu~(2+)含量;随As A浓度的增加,苗长、根长、植株生物量、根系耐性指数、根系活力以及POD和CAT活性先升高后下降,相对电导率、MDA含量和Cu~(2+)含量先下降后上升,SOD和APX活性则一直增加.结果显示,外源添加0.25 mmol·L~(-1)的As A能提高广藿香幼苗细胞清除活性氧的能力,一定程度上缓解40μmol·L~(-1)Cu~(2+)胁迫对膜系统的伤害,减轻Cu~(2+)胁迫对广藿香幼苗生长的毒害作用.     

铝锰复合胁迫下臭牡丹抗逆性及其DNA损伤的研究

以臭牡丹(Clerodendrum bungei Steud.)幼苗为试验对象,配制Al~(3+)浓度梯度为0.00、0.05、0.20、0.40和0.80 mmol·L~(-1),Mn~(2+)浓度梯度为0.00、2.00、4.00、8.00和12.00 mmol·L~(-1)的胁迫液,在土培条件下进行单一和复合胁迫处理,研究10、20、30 d后臭牡丹幼苗的抗氧化酶含量等生理应答及DNA状态,以探究臭牡丹对Al、Mn胁迫的抗性,以期为臭牡丹的扩大生产提供参考,为植物抗逆性研究奠定基础。实验结果表明:(1)Al-Mn复合胁迫对3种抗氧化酶的互作效应有所不同,超氧化物歧化酶活性随胁迫浓度升高而降低,最高抑制率达45.1%,趋势与单一胁迫处理大致相似;过氧化物酶活性在复合胁迫下呈先升后降趋势,且低浓度复合胁迫处理所受影响小于单一胁迫处理,高浓度下则抑制效应加重;相较铝、锰单一胁迫处理,低浓度复合胁迫使过氧化氢酶活性分别提高84.1%和140.1%,高浓度则分别降低61.5%和40.1%;(2)Al~(3+)、Mn~(2+)共存时均促进丙二醛、脯氨酸含量的积累,表现为协同效应;(3)利用CASP软件对彗星电泳图像进行分析,结果显示,低浓度Al~(3+)、Mn~(2+)单一及复合胁迫下,臭牡丹根系DNA几乎没有受到损伤,而当胁迫较强时(Al 0.80 mmol·L~(-1)、Mn 12.00 mmol·L~(-1)、Al 0.40 mmol·L~(-1)-Mn 8.00 mmol·L~(-1)、Al 0.80 mmol·L~(-1)-Mn 12.00 mmol·L~(-1)),OTM大幅增加,Al 0.40 mmol·L~(-1)-Mn 8.00 mmol·L~(-1)复合胁迫分别是单一胁迫的1.40倍和1.44倍,且T3较T4增幅达67.9%,说明高浓度胁迫造成的损害较严重,复合胁迫产生的损伤较单一胁迫更强。综合分析认为:低浓度单一金属离子对臭牡丹生长具有一定促进作用,而当铝、锰浓度分别大于或等于0.40 mmol·L~(-1)和8.00 mmol·L~(-1)时则会对其造成损伤,且复合处理对不同指标具有不同效应。因而,在实际大规模生产中应考察土壤金属离子的种类和浓度,依据臭牡丹的耐受程度选择合适的培育土壤。     

无机砷短期胁迫对铜藻幼苗氧化损伤、抗氧化酶及抗氧化物的影响

为探讨无机砷胁迫对铜藻(Sargassum horneri)的生理影响,对铜藻幼苗在不同浓度(0、50、100、150、200 mmol·L~(-1))的As~(3+)、As~(5+)短期胁迫条件下其氧化损伤、抗氧化酶、抗氧化物等8项生理指标进行了测定。结果显示,随着As~(3+)、As~(5+)浓度的增加,铜藻体内的氧自由基(Oxygen free radical,OFR)产生速率、丙二醛(Malondialdehyde,MDA)含量明显升高,铜藻细胞损伤率也同时上升。As~(3+)、As~(5+)对铜藻的半效应浓度(Median effect concentration,EC_(50))分别为50.1、116.3 mmol·L~(-1)。随As处理浓度升高,藻体超氧化物歧化酶(Superoxide dismutase,SOD)和过氧化物酶(Peroxidase,POD)活性呈上升趋势,而过氧化氢酶(Catalase,CAT)活性则无明显变化。谷胱甘肽(Glutathione,GSH)含量随As~(3+)浓度的增加呈先升后降,而随As~(5+)浓度的增加总体呈上升趋势。非蛋白巯基化合物(Non-protein thiol,NPT)含量随As~(3+)、As~(5+)浓度的升高而先升后降。对铜藻抗氧化系统主成分分析表明,As~(3+)50mmol·L-1及As~(5+)100mmol·L~(-1)实验组的铜藻抗氧化综合得分较高;随着As~(3+)、As~(5+)浓度的升高,抗氧化物(GSH、NPT)对铜藻抗氧化系统的贡献减弱,而抗氧化酶(SOD、POD)对铜藻抗氧化系统的贡献相对增强。     

In vitro and in vivo inhibition of Ca2+-Mg2+-ATPase activity by cadmium in post larvae of Penaeus monodon

Ca²⁺-Mg²⁺-ATPase is a membrane-bound enzyme and is responsible for regulating cytosolic free calcium. In vitro and in vivo effects of cadmium were studied on Ca²⁺-Mg²⁺-ATPase activity in plasma membrane/mitochondrial fraction of Penaeus monodon post larvae. In vitro studies revealed a concentration-dependent decrease in enzyme activity with an IC₅₀ value of 11.02?µM. In vivo experiments were conducted by exposing the post larvae to 1/10th (0.12?ppm) and 1/5th (0.24?ppm) of LC₅₀ values of cadmium for 30 days. Both ATPase activity and metal accumulation were estimated in post larvae exposed to 0.12 and 0.24?ppm of cadmium at different intervals of 24?h, 48?h, 96?h, 10 days and 30 days. ATPase activity showed a gradual decrease in post larvae on exposure to both the sub-lethal concentrations with respect to their controls and the decrease was significant (p?相似文献   

Gas–liquid chromatography for fenvalerate residue analysis: alterations in the ionic concentration and associated adinosine triphosphatases in fish,Cirrhinus mrigala (hamilton)

In the present study, an attempt has been made to quantify the fenvalerate accumulated in different tissues (gill, muscle and liver) and observe changes involved in the levels of sodium, potassium and calcium ions and Na⁺–K⁺, Mg²⁺ and Ca²⁺ adenosine triphosphatase (ATPase) activities in the freshwater fish, Cirrhinus mrigala on short-term and long-term exposure to the median lethal and sublethal concentration of fenvalerate. Residue analysis using gas–liquid chromatography (GLC) technique revealed that fenvalerate accumulated in highest quantity in gill followed by liver and muscle under median lethal concentration (6?µg?L^?1). Whereas in sublethal concentration (0.6?µg?L^?1), muscle accumulated highest quantity followed by gill and liver, which might be due to the fact that fenvalerate is highly lyphophilic. The ion concentration and ATPase activity were found effected in fish exposed to lethal and sublethal concentrations of fenvalerate. Concentration of Na⁺, K⁺ and Ca²⁺ ions decreased in gill, muscle and liver on being exposed to median lethal concentration to a significant level. Whereas the changes were not highly pronounced at sub lethal level indicating low concentration of fenvalerate and its non-toxic effect at chronic exposure. Na⁺–K⁺, Mg²⁺ and Ca²⁺ ATPases activity were also found decreased in correspondence to the ionic change under median lethal and sub lethal concentrations in target tissues. This might have lead to behavioural changes and create wide-spread disturbance in the normal physiology, ultimately causing the death of the fish. The results suggest that in biomonitoring programmes, ions and associated ATPases can be a good diagnostic tool for fenvalerate toxicity.     

ZnO纳米粒子通过线粒体通路抑制小鼠光感受器细胞Na~+/K~+-ATP酶表达和活性的作用研究

氧化锌(ZnO)纳米粒子已被发现具有生物毒性,氧化应激被认为是最重要的因素之一。前期实验证实,ZnO纳米粒子能显著减少锰超氧化物歧化酶(Mn SOD)蛋白的表达,降低Mn SOD活性。本文通过检测乳酸脱氢酶(LDH)释放、线粒体活性氧(ROS)水平和膜电位(Δφm)、延迟整流钾电流变化和Na~+/K~+-ATP酶的表达及活性等变化,检测ZnO纳米粒子对小鼠光感受器细胞的细胞毒作用。结果表明,ZnO纳米粒子可显著增强小鼠光感受器细胞中LDH的释放、增加线粒体内ROS水平并下调Δφm、阻断延迟整流钾电流,同时降低Na~+/K~+-ATP酶的表达及活性,从而对小鼠视网膜光感受器细胞产生细胞毒作用,提示ZnO纳米粒子可通过线粒体通路引起氧化应激,从而抑制小鼠光感受器细胞Na~+/K~+-ATP酶表达和活性,产生细胞毒性,导致细胞死亡。本文的研究结果有助于理解ZnO纳米粒子引起细胞毒性的作用机理。     

Ethyl mercury induces Ca2+ uptake through the P2×7 receptor in a mouse cerebellar microglia cell line

Many observations are reported that organic mercury compounds are involved in increasing intracellular Ca²⁺ levels. However, the issue of which substances on the cell membrane participate in the Ca²⁺ uptake that is induced by ethyl mercury is unclear. The findings of this study suggest that the P2X receptor participates in this process. The uptake of Ca²⁺ by C8-B4 cells was induced in the presence of ethyl mercury. Ca channels in the cell membrane were not affected in this process. In contrast, pretreatment with suramin, an antagonist of the P2X receptor, inhibited the Ca²⁺ uptake induced by ethyl mercury, and also brilliant blue G, a nonselective antagonist of P2×4, P2×5, and P2×7 receptors. In addition, A438079 and A740003, selective antagonists of P2×7 receptor, reduced Ca²⁺ uptake, while 5-BDBD, a selective antagonist of P2×4 receptor, did not. Furthermore, the mRNAs of both the P2×4 and P2×7 receptors were expressed in the presence of ethyl mercury, but the P2×5 receptor mRNA was not. These findings suggest that ethyl mercury may induce Ca²⁺ uptake through the P2×7 receptor of the cell membrane.     

Alterations in serum electrolyte levels after dimethoate exposure and recovery in the freshwater air-breathing catfish,Heteropneustes fossilis (Bloch)

Dimethoate, a moderately toxic insecticide, has a wide range of agricultural and domestic applications. Like other organophosphates, dimethoate has anticholinesterase activity. Fish are non-target organisms, inadvertently exposed to pesticides and their metabolic products. The present study includes short-term (96 h) and long-term (36 d) effects of dimethoate exposure on some serum electrolytes Ca²⁺, Mg²⁺, and Pi in the freshwater air-breathing catfish Heteropneustes fossilis. The concentration of dimethoate for short-term exposure was 2.24 mg L^?1 (75% of 96 h LC₅₀) and for long-term exposure 0.75 mg L^?1 (25% of 96 h LC₅₀). The study includes the recovery pattern in serum electrolytes after placing the fish in pesticide-free water. Fish show hypocalcemia, hypermagnesemia, and hyperphosphatemia after short-term and long-term exposure to dimethoate. When placed in pesticide-free water, these electrolytes exhibit recovery towards normalization, indicating significant (p < 0.05) recovery.     

Arsenic (V) removal from groundwater by GE-HL nanofiltration membrane: effects of arsenic concentration, pH, and co-existing ions

A laboratory-scale investigation was performed to study arsenic (As (V)) removal by negatively charged GE-HL nanofiltration (NF) membrane in simulated drinking water. Effects of As (V) concentration (0–200 μg·L^?1), pH, and co-ions and counter-ions were investigated. The NF membrane presented good stability, and the rejection rates exceeded 90%. The rejection rates of As (V) decreased with the increase of As (V) concentration, while it increased with the increase of pH (reached 96% at pH 6.75). Moreover, a negative relationship was observed between the co-existing ions of Cl^?, Na⁺, SO ₄ ^2? , and Ca²⁺ and the removal of As (V), in which bivalent ions presented more significant effects than monovalent ions.     

Effects of lead on calmodulin content,proliferation and interleukin-2 in lymphocytes of mice

The mechanism inderlying lead (Pb)-induced toxicity was presumed to involve interaction between Pb²⁺ and calcium (Ca²⁺) associated with calmodulin-dependent systems. The aim of this study was to (1) examine the hypothesis that Pb alters calmodulin content and (2) assess the effects of Pb on proliferation and interleukin-2 (IL-2) levels in lymphocytes. The influence of Pb on calmodulin content in mouse lymphocytes was assessed by western blot, while the proliferation of lymphocytes was studied using MTT test, and IL-2 level by ELISA assay. The results showed that 100?µM PbCl₂ decreased calmodulin content, phytohemagglutinin (PHA)-induced proliferation, and IL-2 levels, but a lower concentration (1?µM PbCl₂) did not appear to be effective. Evidence indicates that IL-2 levels and lymphocyte proliferation might not be calmodulin content dependent. Our data suggested that Pb²⁺-induced toxicity was likely to be complex with multiple factors involved, including calmodulin, IL-2, and proliferation of lymphocytes.     

重金属对禾谷镰刀菌的生长及毒素合成的影响

以禾谷镰刀菌为研究对象,研究了常见重金属(Cu、Pb、Zn、Cd)对禾谷镰刀菌菌株生长及其毒素合成的影响。研究结果表明,重金属对菌株的生长和其产毒能力均产生影响。Cu~(2+)和Cd~(2+)对菌株生长影响较大,随着浓度的增加对生长的抑制作用增强,当离子浓度分别为20 mg·L~(-1)和40 mg·L~(-1)时,能够完全抑制菌株生长。Zn~(2+)在0~160 mg·L~(-1)浓度范围内促进菌株生长,在10 mg·L~(-1)浓度下促进毒素合成。Pb~(2+)在察氏培养基中对菌株生长的影响没有明显规律可循,但是,随着Pb~(2+)浓度增加,抑制毒素合成作用增强。     

Antimony induces oxidative stress and cell death in normal hepatocytes

Antimony (Sb) accumulates in the liver which is one of the target organs for metal-mediated toxicity. Although toxicity of Sb was previously investigated, the precise mechanism of Sb-induced hepatotoxicity remains to be determined. The aim of this study was to examine the role of oxidative stress, and mitochondria in the induction of cell death by Sb. Our results showed that liver cell lysis induced by Sb is mediated by reactive oxygen species (ROS) formation, lipid peroxidation and decline of mitochondrial membrane potential (MMP). Antimony-induced ROS formation, lipid peroxidation and reduction of MMP were significantly diminished by antioxidants and ROS scavengers such as dimethyl sulfoxide and mannitol; mitochondrial permeability transition (MPT) pore sealing agents such as carnitine and trifluoperazine; and adenosine triphosphate (ATP) generator, L-glutamine. Antimony-induced ROS formation, lipid peroxidation and fall in MMP were potentiated by glutathione (GSH) depletion via n-bromoheptane. MPT pore sealing agents and ATP generator inhibited hepatotoxicity, indicating Sb-activated cell death via mitochondrial pathway. Pretreatment of hepatocytes with antioxidants and ROS scavengers also blocked cell death induced by Sb, whereas GSH depletion enhances Sb-induced cell death, suggesting that oxidative stress may be directly involved in the reduction of MMP. These findings contribute to a better understanding of the mechanisms that mediate Sb-induced cell death in isolated rat hepatocytes.