Cytogenetic studies of chromium (III) oxide nanoparticles on Allium cepa root tip cells

The current study evaluates the cytogenetic effects of chromium (III) oxide nanoparticles on the root cells of Allium cepa. The root tip cells of A. cepa were treated with the aqueous dispersions of Cr₂O₃ nanoparticles (NPs) at five different concentrations (0.01, 0.1, 1, 10, and 100 μg/mL) for 4 hr. The colloidal stability of the nanoparticle suspensions during the exposure period were ascertained by particle size analyses. After 4 hr exposure to Cr₂O₃ NPs, a significant decrease in mitotic index (MI) from 35.56% (Control) to 35.26% (0.01 μg/mL), 34.64% (0.1 μg/mL), 32.73% (1 μg/mL), 29.6% (10 μg/mL) and 20.92% (100 μg/mL) was noted. The optical, fluorescence and confocal laser scanning microscopic analyses demonstrated specific chromosomal aberrations such as—chromosome stickiness, chromosome breaks, laggard chromosome, clumped chromosome, multipolar phases, nuclear notch, and nuclear bud at different exposure concentrations. The concentration-dependent internalization/bio-uptake of Cr₂O₃ NPs may have contributed to the enhanced production of anti oxidant enzyme, superoxide dismutase to counteract the oxidative stress, which in turn resulted in observed chromosomal aberrations and cytogenetic effects. These results suggest that A. cepa root tip assay can be successfully applied for evaluating environmental risk of Cr₂O₃ NPs over a wide range of concentrations.     

两种兽药添加剂对蚯蚓的DNA损伤及其联合效应

采用土壤中的指示生物赤子爱胜蚓（Eisenia foetida）作为受试生物,研究了两种兽药添加剂四环素和金霉素对赤子爱胜蚓的急性毒性.结果表明：滤纸接触法染毒48h后,这两种兽药添加剂在所设最大受试剂量内没有引起蚯蚓死亡,半致死浓度LC50〉3.98×10^-2mg·cm^-2.应用彗星试验检测蚯蚓体腔细胞的DNA损...     

修复方式对滩涂贝类养殖底质TN、TP及TOC影响的室内模拟实验

通过室内模拟实验方法,探讨了物理修复方式(翻耕、压沙加翻耕)和投放双齿围沙蚕(Perinereis aibuhitensis)的生物修复方式下滩涂文蛤(Meretrix meretrix)养殖区底质中TN、TP及TOC含量的变化特征.结果表明,物理修复组中,翻耕20 cm组底质TN、TOC的去除效果及翻耕30cm和翻耕加压沙组底质TN、TP及TOC的去除效果较对照组均达到了显著水平(p0.05),且不同修复组对3种指标的去除率大小顺序一致,均表现为翻耕加压沙组最佳,翻耕30 cm组次之,翻耕20 cm组最差;生物修复组中,双齿围沙蚕对底质修复效果明显,0.28 kg·m-2密度组对TN、TP的去除效果及0.14 kg·m-2、0.21 kg·m-2密度组对TN、TP及TOC的去除效果均较对照组达到了显著水平(p0.05),其中,0.21 kg·m-2密度组对TN、TP及TOC的修复效果均最佳,而较高密度的0.28 kg·m-2组的修复效果反而降低,说明沙蚕总体修复效果并不完全随投放密度的增加而增强.     

不同磷源及其浓度对铜绿微囊藻生长和产毒的影响

研究了以低浓度磷酸氢二钾和β-甘油磷酸钠为外加磷源时铜绿微囊藻生长及藻毒素产生的规律.通过分析铜绿微囊藻生长过程中细胞数量、培养基和藻细胞中总磷含量、培养基pH及微囊藻毒素-LR和微囊藻毒素-RR的含量,确定了2种磷源对铜绿微囊藻生长及胞内藻毒素含量的变化规律.结果显示,以β-甘油磷酸钠为磷源时,培养过程中藻细胞数及藻细胞内毒素含量均低于以磷酸氢二钾为磷源时的藻细胞数及藻细胞内毒素含量,表明在低浓度范围内磷酸氢二钾比β-甘油磷酸钠更能促进藻的生长,同时也能促进胞内藻毒素的生成.     

Fe掺杂对MnO_x催化剂结构性质及低温SCR反应机制的影响

采用Fe对MnOx催化剂的低温选择性催化还原（SCR）活性进行改性,并通过N2吸附、X射线衍射（XRD）、X射线光电子能谱（XPS）及原位漫反射傅里叶红外（insituDRIFTS）重点探讨了Fe引入后催化剂结构性质的变化及对低温SCR反应机制的影响.结果表明,Fe的掺杂能显著提高催化剂的低温SCR性能,Fe/（Fe＋...     

On the effect of Fe(III) on proliferation of Microcystis aeruginosa at high nitrate and low chlorophyll condition

The impact of Fe concentrations on the growth of Microcystisaeruginosa in aquatic systems under high nitrate and low chlorophyll conditions was studied. The responses of cell density, total and cell chlorophyll-a intracellular Fe content and organic elemental composition of M. aeruginosa to different concentration gradients of Fe(III) in the solutions were analysed. The results showed that the proliferation speeds of M. aeruginosa were: (1) decelerated when the Fe(III) concentration was lower than 50 μg/L in the solutions, (2) promoted and positively related to the increase of Fe(III) concentration from 100 to 500 μg/L in the solutions over the experimental period, and (3) promoted in the early stage but decelerated in later stages by excess adsorption of Fe by cells when the Fe(III) concentration was higher than 500 μg/L in the solutions. The maximum cell density, total and cell chlorophyll-a were all observed at 500 μg Fe(III)/L concentration. The organic elemental composition of M. aeruginosa was also affected by the concentration of Fe(III) in the solutions, and the molecular formula of M. aeruginosa should be expressed as C_7–7.5H₁₄O_0.8–1.3N_3.5–5 according to the functions for different Fe(III) concentrations. Cell carbon and oxygen content appeared to increase slightly, while cell nitrogen content appeared to decrease as Fe(III) concentrations increased from 100 to 500 μg/L in the solutions. This was attributed to the competition of photosynthesis and nitrogen adsorption under varying cell Fe content.     

镉对长江华溪蟹金属硫蛋白mRNA表达的诱导及低分子量壳聚糖的联合作用

采用实时荧光定量PCR法,研究了不同浓度镉（Cd2＋）对长江华溪蟹（Sinopotamon yangtsekiense）金属硫蛋白（metallothionein,简称MT）在肝胰腺、鳃、肌肉和心脏中mRNA表达的诱导作用及低分子量壳聚糖（lowmolecular weight chitosan,简称LMWC）的联合作...