谷胱甘肽对甲醛所致Hela细胞毒性的影响

为研究还原型谷胱甘肽(GSH)对甲醛所致Hela细胞毒性的影响,采用体外染毒方式,应用KC1-SDS法和MTT法分别检测GSH对甲醛引起Hela细胞DNA-蛋白质交联(DPC)和细胞活性的影响.结果表明,250μmol·L-1浓度下,DNA-蛋白质交联实验中甲醛染毒组所致的DPC显著高于对照组(p＜0.01),GSH+...     

细胞色素P450酶代谢新烟碱类农药N-脱烷基反应的机制研究：以噻虫嗪为例

生物转化是影响有机污染物毒性的重要过程,细胞色素P450酶在其中起着关键作用.新烟碱类农药对于哺乳动物毒性较低,但是经过P450酶的转化后,可能会产生毒性增强的代谢产物,提高环境和健康风险.本研究以噻虫嗪（TMX）为例,采用计算模拟的方法研究P450酶催化下TMX的代谢路径和产物,探讨该类污染物N-脱烷基的反应机制.计算结果表明,P450酶代谢TMX有两条不同路径：一条是经过两次O-亚甲基羟基化后通过水桥开环生成毒性减小的噻虫胺（CLO）;另一条是通过氢提取/羟基反弹羟基化甲基的过程,然后经水桥转移氢质子发生N-脱甲基反应,生成去甲基噻虫嗪（dm-TMX）,据前人实验报道该产物会导致肝肿瘤发生率的增加,具有明显的健康风险.鉴于其他烷基胺类化合物具有类似的代谢机理,进一步通过C—H键解离能(BDE_C-H)与氢提取反应的活化能（ΔE^*）建立了N-脱烷基化反应活性的预测模型,R²=0.932,平均绝对误差MAE=1.75 kcal·mol^-1,模型的稳健性良好,可以快速有效地为该类污染物的代谢活性研究提供...     

磷对常见淡水微囊藻释放β-环柠檬醛（β-cyclocitral）的影响

藻类释放的异味化合物导致水体嗅味问题已成为世界性的水环境问题之一,引起了社会的广泛关注.通过室内实验,研究了磷（P）对8种常见微囊藻（Microcystis）释放异味物质—β-环柠檬醛（β-cyclocitral）的影响.结果表明,P对微囊藻生长及释放β-cyclocitral有较大影响,其中,中低P浓度（0~0.5 mg·L^-1）有利于多数种类的微囊藻生长,但对藻类活性（F_v/F_m）的影响与叶绿素a（Chl-a）并不一致.铜绿微囊藻（Microcystis aeruginosa）释放β-cyclocitral的能力与P浓度成正比,也是常见微囊藻中β-cyclocitral产率（β-cyclocitral/Chl-a）最高的藻类,可达34.2 ng·μg^-1, 其次为华美微囊藻（Microcystis elabens）达24.1 ng·μg^-1,惠氏微囊藻（Microcystis wesenbergii）的β-cyclocitral产率最低,仅为0.21 ng·μg^-1.数据分析表明不同种微囊藻,在不同P浓度下释放β-cyclocitral的巨大差异与其产率紧密相关,β-cyclocitral产率与藻类活性（F_v/F_m）紧密相关.结合文献报道的野外调查数据分析,同样表明在富营养化湖泊中随着P浓度的升高,铜绿微囊藻（Microcystis aeruginosa）释放β-cyclocitral增加,与室内实验结果一致.本研究通过室内实验,揭示了P对不同微囊藻生长和活性影响的差异,是造成不同微囊藻释放β-cyclocitral差异的重要原因, 得出P是调节微囊藻释放β-cyclocitral的重要因素,这对富营养化水体中异味物质的防治有重要意义.     

西南典型菜地土壤重金属健康风险和毒性效应

为揭示我国西南典型蔬菜种植区土壤中重金属的污染特征及人体健康风险,选择通海县菜地土壤为研究对象,分析了土壤中Cd、As、Pb、Cr、Ni、Cu和Zn的积累特征,结合体外胃肠模拟法（SBRC）和胃上皮细胞（GES-1）毒性实验评估土壤中重金属生物可给性与人体健康风险,并利用细胞毒性研究验证健康风险.结果表明：菜地土壤中7种重金属仅Cd的平均含量超出农用地土壤污染风险筛选值（GB 15618-2018）,且变异系数（72.73%）最大;Cr、Cd和Zn的平均含量超出了云南省土壤背景值;土壤重金属生物可给性差异较大,Cd的生物可给性（35.31%）最高;研究区可能存在由重金属引起的致癌风险,非致癌风险不明显,Cr、As和Ni是致癌风险的主要贡献元素;基于生物可给性的综合非致癌风险（HI）和综合致癌风险（CR）均小于基于总量的评价结果;健康风险的细胞毒性验证实验表明生物可给态重金属暴露后抑制了细胞活性,改变细胞形态,诱发了明显的胃上皮细胞损伤.     

轮叶黑藻和穗花狐尾藻对铜的吸收机制研究

应用室内模拟试验,通过对铜(Cu)的短期吸收动力学、各亚细胞组分吸收动力学以及Cu的释放研究,探讨了两种沉水植物轮叶黑藻[Hydrilla verticillata(L.f.)Royle]和穗花狐尾藻(Myriophyllum spicatum L.)对Cu的吸收机制.结果表明:①轮叶黑藻和穗花狐尾藻均对Cu具有较高的吸收速率,且两种植物最高吸收速率差异不显著[Vmax(DW)为2μmol·(g·min)-1,P>0.05];②在2μmol·L-1Cu溶液中暴露不同时间(0~96 h),两种沉水植物叶片和茎中各亚细胞组分的Cu含量均迅速增加并约在12 h后达到平衡.各时间处理下,两种植物叶片富集的Cu含量均显著高于茎(P<0.05),并且叶片中的Cu均主要分布在细胞壁(>60%),其次是可溶部分和细胞器;③两种植物相比,黑藻叶片细胞壁中富集的Cu含量显著高于狐尾藻,而细胞内富集的Cu含量差异不显著.轮叶黑藻对Cu的富集和释放能力均高于穗花狐尾藻.     

锌对镉在河南华溪蟹鳃组织亚细胞中富集的影响

为了研究锌对镉在河南华溪蟹(Sinopotamon henanense)鳃中富集的影响,本文选择不同浓度镉锌联合处理14 d和28 d后,采用亚细胞分离法将鳃组织分为热稳定蛋白(HSP)、富含金属颗粒(MRG)、生物活性部分(BAM)和细胞碎片部分(CD),其中,热稳定蛋白(HSP)和富含金属颗粒(MRG)组成生物解毒部分(BDM),利用火焰原子吸收分光光度法(AAS)测定各个亚细胞组分中镉的含量.结果显示,BDM是镉富集的重要场所,镉在其中所占比例达到50%.其中,BDM包括热稳定蛋白(HSP)和富含金属颗粒组分(MRG).随着镉处理浓度的增加,锌对镉在HSP和MRG中的蓄积表现为先促后抑的作用.在BAM中,加锌促进镉的蓄积,且相较于高浓度锌(1000μg·L-1),低浓度锌(100μg·L-1)的促进作用更为显著.研究表明,锌对镉在河南华溪蟹鳃中的富集及分布有一定影响.     

活性氧和钙离子参与镉诱导的酵母细胞死亡过程调节

以酵母为实验材料,研究了镉(以CdCl2形式添加)对细胞的毒性作用机制.结果显示,浓度为0.25~5 mmol·L-1的镉可降低酵母细胞活性,诱导细胞死亡;随着镉浓度的提高和处理时间的延长,细胞死亡率增高.凋亡抑制剂Z-Asp-CH2-DCB与镉共同作用后,细胞死亡率明显低于镉单独处理组.经镉处理后,酵母细胞内的活性氧(ROS)水平显著升高;外源抗氧化剂抗坏血酸和过氧化氢酶能降低镉引发的细胞死亡,特异性Ca2+螯合剂EGTA或Ca2+通道特异性抑制剂LaCl3亦可明显降低镉诱发的细胞死亡率.研究表明,镉诱发的酵母细胞死亡过程存在依赖于caspase途径的细胞凋亡途径;镉诱发的死亡与镉处理组胞内ROS和Ca2+水平升高有关,ROS可能通过增加胞内Ca2+水平,继而激活相关下游信号导致细胞死亡.     

Immunotoxic effects of an industrial waste incineration site on groundwater in rainbow trout (Oncorhynchus mykiss)

The discharge of organic waste from the petrochemical industry into the Mercier lagoons caused major groundwater contamination. The objective of this study was to determine the immunotoxic potential of three groundwater wells at increasing distance from the incinerator dumping site （1.17, 2.74 and 5.40 km）. Rainbow Trout were exposed to increasing concentrations of water from three groundwater wells for 14 days. Immunocompetence was characterized by phagocytosis, mitogen-stimulated proliferation of lymphocytes, cell cycle analysis and apoptosis. A significant increase in innate （phagocytosis） and specific immune response （B lymphocyte proliferation） was observed in trout exposed to water collected from the well at 2.74 km. However, phagocytosis activity was suppressed in groups at 1.17 and 5.40 km. The proportion of lymphocytes in S phase was significantly increased in groups at 2.74 and 5.40 kin, while lymphocytes in G0/G1 phase were decreased in all three exposure groups. Additionally, dexamethasone （DEX）-induced apoptosis of lymphocytes was significantly reduced in the group at 2.74 km, which suggests decreased lymphocyte turnover. Furthermore, the ratio of DEX- induced apoptosis/apoptosis was lower in the groups at 2.74 and 5.40 km. In summary, our experiments have shown that exposure to the mixture of organic compounds present in Mercier groundwater modulates phagocytosis and cell proliferation, disrupts the cell cycle and reduces the ratio of DEX- induced apoptosis/apoptosis. It is concluded that groundwater collected in the vicinity of an incinerator containment field could impact immunocompetence in fish.     

Physiological cellular responses and adaptations of Rhodococcus erythropolis IBBPo1 to toxic organic solvents

A new Gram-positive bacterium, Rhodococcus erythropolis IBBPo1（KF059972.1） was isolated from a crude oil-contaminated soil sample by enrichment culture method. R. erythropolis IBBPo1 was able to tolerate a wide range of toxic compounds, such as antibiotics（800–1000 μg/mL）,synthetic surfactants（50–200 μg/mL）, and organic solvents（40%–100%）. R. erythropolis IBBPo1 showed good tolerance to both alkanes（cyclohexane, n-hexane, n-decane） and aromatics（toluene, styrene, ethylbenzene） with logPOW（logarithm of the partition coefficient of the solvent in octanol–water mixture） values between 2.64 and 5.98. However, alkanes were less toxic for R. erythropolis IBBPo1 cells, compared with aromatics. The high organic solvent tolerance of R. erythropolis IBBPo1 could be due to the presence in their large genome of some catabolic（alkB, alkB1, todC1, todM, xylM）, transporter（HAE1） and trehalose-6-phosphate synthase（otsA1, KF059973.1） genes. Numerous and complex physiological cellular responses and adaptations involved in organic solvent tolerance were revealed in R. erythropolis IBBPo1 cells exposed 1 and 24 hr to 1% organic solvents. R. erythropolis IBBPo1 cells adapt to 1% organic solvents by changing surface hydrophobicity, morphology and their metabolic fingerprinting.Considerable modifications in otsA1 gene sequence were also observed in cells exposed to organic solvents（except ethylbenzene）.     

Seasonal dynamics of water bloom-forming Microcystis morphospecies and the associated extracellular microcystin concentrations in large, shallow, eutrophic Dianchi Lake

The increasing occurrence of Microcystis blooms is of great concern to public health and ecosystem due to the potential hepatotoxic microcystins （MCs） produced by these colonial cyanobacteria. In order to interpret the relationships between variations of Microcyst/s morphospedes and extracellular MC concentrations, the seasonal dynamics of phytoplankton community composition, MC concentrations, and environmental parameters were monitored monthly from August, 2009 to July, 2010. The results indicated that Microcystis dominated total phytoplankton abundance from May to December （96%--99% of total biovolume）, with toxic Microcystis viridis and non-toxic Microcystis wesenbergii dominating after July （constituting 65%- 95% of the Microcystis population）, followed by M. viridis as the sole dominant species from November to January （49%--93%）. Correlation analysis revealed that water temperature and nutrient were the most important variables accounting for the occurrence ofM. wesenbergii, while the dominance ofM. viridis was related with nitrite and nitrate. The relatively low content of MCs was explained by the association with a large proportion of M. viriclis and M. wesenbergii, small colony size of Microcystis populations, and low water temperature, pH and dissolved oxygen. The extracellular MC （mean of 0.5 ± 0.2 μg/L） of water samples analyzed by enzyme-linked immunosorbent assay （ELISA） demonstrated the low concentrations of MC in Dianchi Lake which implied the low potential risk for human health in the basin. The survey provides the first whole lake study of the occurrence and seasonal variability of Microcyst/s population and