Mechanism of Deca-BDE-induced apoptosis in Neuro-2a cells: Role of death-receptor pathway and reactive oxygen species-mediated mitochondrial pathway

Decabromodiphenyl ether (BDE-209) is a prevalent polybrominated diphenyl ether (PBDE) congener known to have neurotoxicity. Effects of BDE-209 on Neuro-2a cells were performed in the present study and the possible apoptotic pathway was discussed. Results indicated that BDE-209 induced Neuro-2a cell apoptosis, increased the protein expression of Fas and Fas-associated death domain-containing protein (FADD) and activated the caspase-8 and -3 activities in a concentration-dependent manner, inferring the death-receptor pathway was involved in the apoptotic process. Meanwhile, BDE-209 exposure increased the Bax/Bcl-2 ratio and decreased the cellular mitochondrial membrane potential (MMP) which led to cytochrome C released to the cytoplasm. The intracellular caspase-9 was elevated simultaneously, which caused downstream caspase cascade and triggered cell apoptosis. Moreover, BDE-209 exposure increased cellular reactive oxygen species (ROS) level in a concentration-dependent manner and the addition of N-acetyl-l-cysteine (NAC), known as ROS scavengers, obviously reduced the apoptotic rate and a positive relationship was observed between the degree of apoptosis blocking and the loss of MMP and ROS production. We thus concluded that BDE-209 induced Neuro-2a cell apoptosis via the combination of the death-receptor signaling pathway and the mitochondrial signaling pathway. The elevated ROS production was considered to magnify the intracellular apoptosis signal and played a crucial role in apoptosis of Neuro-2a cells induced by BDE-209.     

钻井井场噪音对听觉系统影响的观察

对油田井场的特定部位进行声强测定及频谱分析,发现其噪声强度均已超过国家标准。选健康,耳廊反射正常豚鼠30只,分别置于柴油机旁（8只）,钻井平台（8只）和值班房（8只）,余6只为正常对照。每天暴露6h,连续21d,记录豚鼠脑干电位及扫描电镜下形态学改变,结果表明,虽然钻井平台上的噪音强度低于柴油机组,但它对人耳的损伤程度却高于柴油机组。     

13种樟科植物叶油细胞和粘液细胞的分布和结构的比较研究

利用组织透明法、石蜡制片法和薄切片法比较研究了樟科５属１３种植物叶片中油细胞和粘液细胞的分布和结构．结果表明：５属１１种植物叶片中有油细胞分布,其形状多为圆形,体积较小且大小基本一致,ｄ３０～４５μｍ;４属８种植物叶片中有粘液细胞分布,其形状多为椭圆形,体积较大,ｄ６０～１００μｍ．根据透明叶片观察,不同植物油细胞的分布密度不同;从叶片横切面观察,有些种油细胞分布于整个叶肉中,有的分布于栅栏组织与海绵组织之间及海绵组织中,有的仅分布于栅栏组织内．粘液细胞有些种分布于整个叶肉,而有的仅分布于栅栏组织中．因此,叶片内油细胞的分布密度、油细胞和粘液细胞的分布位置及其大小在种与种之间存在明显的差异,此种结构特征具有分类学上的意义     

农药对藻类的生态毒理学研究Ⅰ:毒性效应

随着现代农业的发展,世界范围内使用的农药品种越来越多,用量不断增加。农药对非靶生物的影响以及农药残留导致环境污染,造成生态系统结构和功能的破坏,早已受到了国内外的广泛关注。有关农药对生态系统中消费者类群毒性效应的研究较多。近年来,农药对于生态系统初级生产者－ 藻类的毒性及其生态毒理学的研究倍受重视。大力开展这方面的研究对于深入了解农药在生态系统中的迁移、转化及整体生态效应以及农药的生态风险评价无疑具有重要的理论意义和应用价值。本文综述了近年来国内外有关农药对单种藻类和藻类群落的毒性效应,影响毒性的环境因子。     

脉冲变频电磁场对水中藻类的抑制及去除效能

研究了脉冲变频电磁场对水华鱼腥藻的抑制及去除效果.结果显示,磁场对循环水样表现出很好的杀藻效果,水样在磁场中累积停留时间为6min时,杀藻率可以达到94%,累积停留时间为10min时,杀藻率可以达到96%.处理后的水样,藻细胞密度在120h内没有增加,生长受到抑制,经磁场处理的循环水样"磁记忆"时间可以达到120h.对于静置于磁场中的水样,处理1h后,藻的生长开始受到抑制.不同的处理方式会产生不同的效果,对于脉冲变频磁场,水以运动的形式通过磁场更有利于杀藻.     

粘土矿复合聚合氯化铝凝聚给水中的藻类

采用粘土矿复合聚合氯化铝 (PAC)对凝聚给水中的藻类进行了研究 .结果表明 ,粘土矿的加入不仅可显著增加絮体的密实度 ,加快其沉降速度 ,使沉淀后的活藻絮体在微扰动下不再漂浮上升 ,从而可有效阻止堵塞滤池 ,而且使沉淀后的底泥体积减少了 31 % ,沉降后出水中叶绿素a的浓度降到 1 3μg·l- 1 ,铝的含量低于 0 2mg·l- 1 .     

Model‐Based Nitrogen and Phosphorus (Nutrient) Criteria for Large Temperate Rivers: 2. Criteria Derivation

Nitrogen and phosphorus criteria were developed for 233 km of the Yellowstone River, one of the first cases where a mechanistic model has been used to derive large river numeric nutrient criteria. A water quality model and a companion model which simulates lateral algal biomass across transects were used to simulate effects of increasing nutrients on five variables (dissolved oxygen, total organic carbon, total dissolved gas, pH, and benthic algal biomass in depths ≤1 m). Incremental increases in nutrients were evaluated relative to their impact on predefined thresholds for each variable; the first variable to exceed a threshold set the nutrient criteria. Simulations were made at a low flow, the 14Q5 (lowest average 14 consecutive day flow, July‐September, recurring one in five years), which was derived using benthic algae growth curves and EPA guidance on excursion frequency. An extant climate dataset with an annual recurrence was used, and tributary water quality and flows were coincident with the river's 10 lowest flow years. The river had different sensitivities to nutrients longitudinally, pH being the most sensitive variable in the upstream reach and algal biomass in the lower. Model‐based criteria for the Yellowstone River are as follows: between the Bighorn and Powder river confluences, 55 μg TP/l and 655 μg TN/l; from the Powder River confluence to Montana state line, 95 μg TP/l and 815 μg TN/l. Pros and cons of using steady‐state models to derive river nutrient criteria are discussed.     

彗星电泳法测定双酚A对雄性幼龄小鼠脑细胞的DNA损伤

双酚A是一种日常生活中无处不在的环境雌激素,具有生殖和神经毒性,但低剂量长期暴露对发育期青少年的危害性常常被低估或忽视。本研究以4周龄雄性清洁级小鼠为实验对象,以茶油作为溶媒对照,分别以双酚A浓度为0μg·m L-1、0.1μg·m L-1、10μg·m L-1和1 000μg·m L-1的茶油灌胃小鼠8周,然后利用彗星电泳法检测各组小鼠脑细胞的DNA损伤。结果显示,不同浓度双酚A暴露8周后,彗星电泳图像显示小鼠脑细胞DNA出现不同程度的损伤,随着暴露剂量的增加,带有彗尾的脑细胞比率从对照组小鼠的9.5%分别升高到暴露组小鼠的34.5%、36.0%和50.5%,细胞总体的尾部DNA含量、尾长和尾矩也都逐渐增加,而且各双酚A暴露组小鼠与溶媒对照组小鼠脑细胞都具有显著性差异(P0.01),这说明中长期双酚A暴露(包括低浓度环境暴露)会导致雄性幼龄小鼠脑细胞的DNA损伤。     

纳米硫化镉对A549细胞的损伤研究

研究纳米硫化镉(Nano-Cd S)材料对肺癌细胞系A549的毒性及氧化损伤作用。培养A549细胞,经传代后接种于6孔板中,每孔2 m L完全培养基,接种次日进行染毒。用直径20~30 nm、长度80~100 nm的Nano-Cd S进行染毒,染毒浓度分别为0、5、10、20、40和80 mg·L~(-1)。染毒24 h后用MTT检测细胞存活率,以存活率在80%左右的浓度为后续实验染毒浓度。应用流式细胞技术,用荧光探针法检测A549细胞的活性氧(reactive oxygen species,ROS)含量,PI-Annexin-V法检测细胞凋亡情况;用试剂盒检测细胞中超氧化物岐化酶(superoxide dismutase,SOD)和过氧化氢酶(catalase,CAT)活性以及丙二醛(malondialdehyde,MDA)含量,判断细胞氧化损伤情况。不同浓度Nano-Cd S处理细胞24 h之后,细胞存活率随剂量的增加而下降,浓度为10、20、40和80μg·L~(-1)时,存活率分别为(88.71%±0.80%)、(81.93%±3.06%)、(75.23%±1.13%)和(70.66%±5.63%),且各组间差异均具有统计学意义(P0.05)。以浓度为10和20 mg·L~(-1)的Nano-Cd S染毒24 h后,胞内ROS含量和细胞凋亡率随染毒剂量的增加而增加(P0.05);浓度为10 mg·L~(-1)时,细胞凋亡率为(6.26%±0.44%)。与对照相比,各染毒组SOD和CAT活性和MDA含量升高,20 mg·L~(-1)染毒组SOD和CAT活性和MDA含量高于10 mg·L~(-1)染毒组(P0.05)。研究表明,纳米硫化镉能引起A549细胞的氧化损伤和细胞凋亡,具有明显的细胞毒性。     

底泥扰动下藻类对不同形态磷在水体中分布的影响

研究了反复扰动与藻类共存条件下,水体中溶解性磷、颗粒态磷、生物有效磷的分布规律,并分析了颗粒物质物理化学吸附与藻类生物利用对水体中磷消失的贡献率.结果表明,扰动抑制了水体中藻类生长,叶绿素a增加量仅为3.53μg/L(初始30μg/L)和4.80μg/L(初始120μg/L),而无扰动下该值分别为21.36μg/L (初始30μg/L)和14.49μg/L (初始120μg/L).并且,溶解氧水平和pH值均低于无扰动状态.扰动导致水体中总磷和颗粒态磷显著增加,但溶解性总磷(DTP)和溶解性磷酸盐(DIP)均有所降低.对于DTP而言,扰动状态下,颗粒物质吸附占90%,而无扰动下,则降低至60%,相应地,藻类生物利用则增加至40%.无论扰动与否,BAP基本处于稳定状态,而BAPP占BAP的百分比则有所增加.扰动状态下BAPP占PP的百分比明显低于无扰动状态.这暗示了扰动对水体中磷迁移和转化的作用大于藻.