Primary neuronal-astrocytic co-culture platform for neurotoxicity assessment of di-(2-ethylhexyl) phthalate

Plastics such as polyvinyl chlorides （PVC） are widely used in many indoor constructed environments; however, their unbound chemicals, such as di-（2-ethylhexyl） phthalates （DEHP）, can leach into the surrounding environment. This study focused on DEHP＇s effect on the central nervous system by determining the precise DEHP content in mice brain tissue after exposure to the chemical, to evaluate the specific exposure range. Primary neuronal-astrocyte co-culture systems were used as in vitro models for chemical hazard identification of DEHP. Oxidative stress was hypothesized as a probable mechanism involved, and therefore the total reactive oxygen species （ROS） concentration was determined as a biomarker of oxidative stress. In addition, NeuriteTracer, a neurite tracing plugin with ImageJ, was used to develop an assay for neurotoxicity to provide quantitative measurements of neurological parameters, such as neuronal number, neuron count and neurite length, all of which could indicate neurotoxic effects. The results showed that with 1 nmol/L DEHP exposure, there was a significant increase in ROS concentrations, indicating that the neuronal-astrocyte cultures were injured due to exposure to DEHP. In response, astrocyte proliferation （gliosis） was initiated, serving as a mechanism to maintain a homeostatic environment for neurons and protect neurons from toxic chemicals. There is a need to assess the cumulative effects of DEHP in animals to evaluate the possible uotake and effects on the human neuronal system from exoosure to DEHP in the indoor environment.     

2000年1月15日姚安6.5级地震余震序列震源机制解与震源区应力场分析

本文利用垂直向的Pg和Sg波的最大振幅比方法,计算2000年1月15日云南姚安6.5级地震后余震序列震源机制解,通过统计和系统聚类分析,再结合震中分布图,综合分析了云南姚安6.5级地震的震源机制解和震源区应力场破裂特征,研究结果表明震源断层的走向为SEE-NWW占主导,其平均解为120°,震区主压应力轴平均解为145°,即SSE向,与震源区现今构造应力场主压应力方向一致,表明余震的应力场主要受区域应力场的控制.     

再悬浮过程中河流底泥PAHs的迁移与释放

利用再悬浮模拟(particle entrainment simulator,PES)装置模拟了河流底泥在受到上层扰动力后的再悬浮过程.结果表明,沉积物性质如粒径组成及PAHs含量对沉积物再悬浮过程中PAHs的释放影响显著.再悬浮过程中上覆水体总悬浮颗粒物(total suspended solids,TSS)含量与颗粒态PAHs之间存在极显著相关关系.切应力对再悬浮过程中PAHs释放的影响体现在两方面.一方面,单位体积的颗粒态PAHs随切应力增大而增大;另一方面,悬浮颗粒上PAHs的富集效应随切应力增大而减弱,是由于切应力强烈导致吸附作用弱的大颗粒进入水体.上覆水体中的PAHs总量在一段时间上升后于120 min或240min趋于稳定,而颗粒态与溶解态之间具有良好响应.高低环PAHs释放行为差异显著,由于中高环PAHs的疏水性,上覆水体中检测到的多为3~4环个体.     

CdSe/ZnS量子点对稀有鮈鲫胚胎发育的影响及其氧化应激作用

本研究以稀有鮈鲫(Gobiocypris rarus)为对象,研究了不同浓度CdSe/ZnS量子点(QDs)暴露下,稀有鮈鲫胚胎发育过程中自主运动频率、内心率和体长的变化,以及利用体内超氧化物歧化酶(SOD)和丙二醛(MDA)作为毒性指标,反映CdSe/ZnS QDs暴露对稀有鮈鲫胚胎发育的氧化应激作用.结果显示:CdSe/ZnS QDs对稀有鮈鲫胚胎72 hpf(hours post fertilization)的半致死浓度(LC50)为319.629 nmol·L-1,96 hpf的半致畸浓度(EC50)为203.312 nmol·L-1.CdSe/ZnS QDs暴露不仅影响稀有鮈鲫胚胎死亡率、畸形率、自主运动频率、孵化时间和孵化率,而且使其内心率减缓、体长缩短,导致胚胎卵凝结,心包囊肿,出现脊椎弯曲等多种毒性现象.同时发现,CdSe/ZnS QDs暴露导致稀有鮈鲫体内MDA含量增加以及SOD活力的降低.这表明CdSe/ZnS QDs对稀有鮈鲫胚胎发育具有致畸、致死作用,而氧化应激可能是引起其胚胎致畸、致死的重要机制之一.     

锌铜胁迫对Bacillus vallismortis EPS组分变化特征及其吸附性能的影响

近年来,微生物胞外聚合物(EPS)在吸附重金属方面的潜能引起了人们的广泛关注,但关于重金属对微生物及其EPS特性的影响鲜有报道.Bacillus vallismortis对锌铜矿捕收剂苯胺黑药具有良好的降解能力.为了解重金属对菌株的胁迫影响,探讨二者之间的相互作用,研究了Zn(Ⅱ)、Cu(Ⅱ)胁迫对菌株EPS产量、组分变化特征及其吸附性能的影响.结果表明,在Zn(Ⅱ)胁迫下,菌株培养至稳定期产生的EPS最多,当Zn(Ⅱ)为12 mg·L~(-1)时EPS产量翻倍,达到100.84 mg·g~(-1)(以VSS计),Zn(Ⅱ)能刺激菌株产生更多富含—COOH和—OH的胞外多糖;菌株在Cu(Ⅱ)胁迫下需培养至对数期产生的EPS最多,在Cu(Ⅱ)为6 mg·L~(-1)情况下EPS产量最高为60.65 mg·g-1(以VSS计),Cu(Ⅱ)的胁迫作用提高了菌株EPS中富含N—H和C—N的蛋白质含量;吸附实验结果表明,2种金属能通过胁迫菌株产生特异性EPS,为金属离子提供大量适用性结合点位,显著提高对重金属的去除能力.研究结果对应用生物法处理同时含有重金属和有机物的复合型选矿废水具有一定的指导意义.     

玉米光谱小波奇异熵的铜污染监测研究

不同浓度铜离子(Cu2+)胁迫梯度下的玉米叶片光谱存在细微差异,但传统的光谱相似性测度方法难以区分健康的与受污染的玉米叶片光谱间的变异信息.为此,本文结合小波变换和奇异熵理论,构建小波奇异熵(Wavelet Singular Entropy,WSE)方法用于Cu2+胁迫下的玉米污染程度分析与污染监测.通过设置不同浓度Cu2+胁迫梯度下的玉米盆栽实验,依据玉米叶片的光谱测量数据和所测定的叶片中Cu2+含量,并与绿峰高度(Green-peak Height,GH)和红谷吸收深度(Red-valley Depth,RD)光谱特征参数法污染监测应用结果进行对比分析,研究WSE方法的Cu2+污染监测效果.结果表明,WSE值与Cu2+胁迫梯度、玉米叶片中Cu2+含量呈显著正相关,WSE值大小能够较好地表征叶片光谱的污染信息奇异性及其污染程度.     

双层板桁钢梁应力分析

以跨度最大的双层斜拉桥闵浦大桥为背景,研究了双层板桁钢梁桥面板的受力特性,阐述了精细壳单元与梁单元结合的整体有限元模型,并分析了上、下桥面间腹杆的受力特性与桥面板的应力分布特性;采用桥面纵横梁间带U肋精细桥面模型,分析了桥面板和U肋在车辆荷载作用下的应力分布.研究表明,上、下层桥面横桥向应力小于纵桥向应力,并且横桥向应...     

干旱胁迫下壳聚糖对花生幼苗生理特性的影响

为了研究壳聚糖对花生幼苗抗旱言的影响，以花生品种“花育23号”为材料，在干旱胁迫下，用不同浓度的壳聚糖溶雍处理花生幼苗，连续处理5d后测定叶绿素、可溶性蛋白、MDA和脯氨酸的含量变化。结果表明，花生幼苗在干旱条件下喷施壳聚糖与蒸馏水相比，在干旱第10天叶绿素含量提高了42．2％，MDA含量降低了36．2％；在干旱第6天，可溶性蛋白含量提高了129．0％；在干旱第8天，脯氨酸含量提高了257．0％。喷施壳聚糖溶液的最适宜浓度为0．10g／L，喷施该浓度壳聚糖可促进植物生长，增强抗旱性。     

Accumulation of mercury and its effect on antioxidant enzymes in brain,liver, and kidneys of mice

Abstract

The effect of mercuric chloride (HgCl₂) on the activities of catalase, Superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR) and its effect on glutathione (GSH) content were evaluated in different organs (liver, kidneys, and brain) of mice after administration at 0, 0.25, 0.5 and 1.0 mg/kg/day for 14 days. The uptake of mercury shows that the kidneys accumulated the highest levels of mercury compare to brain and liver. The enzyme levels varied in mercury treated organs compare to control. A dose dependent increase of antioxidant enzymes occurred in the liver and kidneys. The increase in enzyme activities correlated with highest mercury accumulation in the kidneys and liver. Mercury is known to generate reactive oxygen species (ROS) in vivo and in vitro, therefore, it is likely that enzyme activities increased to scavenge ROS levels produced as a result of mercury accumulation. Glutathione content increased in liver and kidneys of mercury treated mice compare to control. The results showed that the highest oral dose of mercury significantly increased antioxidant enzymes in kidneys and liver. The increased antioxidant enzymes enhance the antioxidant potential of the organs to reduce oxidative stress.     

Impact of genetic diversity and inbreeding on the life-history of Chironomus midges over consecutive generations

We report results of a multigenerational experiment with Chironomus riparius. Two strains with a high and a low level of genetic variability were exposed to a low, environmentally relevant TBT concentration of 80 μg Sn kg⁻¹ sediment dw nominally (time weighted mean, based on measured concentrations: 4.5 μg Sn kg⁻¹ sediment dw), and various life history traits as well as genetic diversity were monitored for eleven consecutive generations. While TBT effects are hardly visible in the outbred and genetically diverse strain, the inbred and genetically impoverished strain shows a clearly reduced population growth rate compared to the control. Moreover, the impoverished strain shows an increase in fitness over time. Analyses of variation at five microsatellite loci revealed that the level of genetic variation is strongly reduced in the inbred compared to the outbred strain. Moreover, genetic diversity increases over time in the inbred strain. This finding explains the observed increase in fitness in both inbred lineages (control and TBT exposed). The results document that inbreeding and the level of genetic diversity might be of crucial importance in populations under pollution stress. Furthermore, ecotoxicological bioassays have to consider genetic diversity if results between laboratories should be comparable. Our data provides evidence that genetic diversity strongly contributes to the survival of a population exposed to chemical pollution.