北京大气PM_(2.5)对A549细胞炎性因子及DNA损伤的毒性

为探讨大气PM_(2.5)及其不同组分对人肺上皮细胞A549的毒性作用及其剂量-反应关系,将前期采集的PM_(2.5)颗粒物用不同方法进一步制备PM_(2.5)水溶性组分、PM_(2.5)脂溶性组分和PM_(2.5)单纯颗粒物,将制备的PM_(2.5)颗粒物及其组分以不同浓度(10,50,100,200,400μg/m L)对A549细胞染毒,用MTS法分别在染毒6,10,24,48,72h后测定细胞活力,染毒24h后用ELISA及RT-QPCR法测定炎性因子IL-6和TNF-α表达量,AP位点计数法测定细胞DNA损伤情况.结果表明:除PM_(2.5)水溶性组分外,其余染毒样本高浓度染毒时始终对细胞生长表现出抑制作用,其中低浓度染毒时可在较短时间对细胞生长表现出抑制作用,染毒时间较长时抑制作用减弱或消失,PM_(2.5)水溶性组分对细胞生长抑制作用并不显著;除PM_(2.5)水溶性组分外,其余染毒样本都显著升高了IL-6m RNA的相对表达量和IL-6蛋白的分泌,除PM_(2.5)脂溶性组分外,其余染毒样本都显著升高了TNF-αm RNA的相对表达量;除PM_(2.5)水溶性组分外,其余染毒样本都显著提高了DNA碱基缺失程度.总的来说,PM_(2.5)水溶性组分在抑制细胞活力、造成炎性损伤及DNA损伤方面作用相对较小,而PM_(2.5)所产生的毒性作用并不仅限于其所吸附的复杂成分,其中作为载体的固体核心颗粒对机体可能造成的毒性作用也不容忽视.     

Repeated batch and continuous degradation of chlorpyrifos by Pseudomonas putida

The present study was undertaken with the objective of studying repeated batch and continuous degradation of chlorpyrifos (O,O-diethyl O-3,5,6-trichloropyridin-2-yl phosphorothioate) using Ca-alginate immobilized cells of Pseudomonas putida isolated from an agricultural soil, and to study the genes and enzymes involved in degradation. The study was carried out to reduce the toxicity of chlorpyrifos by degrading it to less toxic metabolites. Long-term stability of pesticide degradation was studied during repeated batch degradation of chlorpyrifos, which was carried out over a period of 50 days. Immobilized cells were able to show 65% degradation of chlorpyrifos at the end of the 50th cycle with a cell leakage of 112 × 10³ cfu mL^?1. During continuous treatment, 100% degradation was observed at 100 mL h^?1 flow rate with 2% chlorpyrifos, and with 10% concentration of chlorpyrifos 98% and 80% degradation was recorded at 20 mL h^?1 and 100 mL h^?1 flow rate respectively. The products of degradation detected by liquid chromatography–mass spectrometry analysis were 3,5,6-trichloro-2-pyridinol and chlorpyrifos oxon. Plasmid curing experiments with ethidium bromide indicated that genes responsible for the degradation of chlorpyrifos are present on the chromosome and not on the plasmid. The results of Polymerase chain reaction indicate that a ~890-bp product expected for mpd gene was present in Ps. putida. Enzymatic degradation studies indicated that the enzymes involved in the degradation of chlorpyrifos are membrane-bound. The study indicates that immobilized cells of Ps. putida have the potential to be used in bioremediation of water contaminated with chlorpyrifos.     

The effects of benomyl and its breakdown products carbendazim and butyl isocyanate on the structure and function of tracheal ciliated cells

Abstract

The effects of the fungicide benomyl and its breakdown products, carbendazim and butyl isocyanate, were examined on canine tracheal epithelial tissue in primary culture. Changes in ciliary frequencies were monitored with an optical spectrum analysis system. Serial dilutions of the test compounds were prepared in 100% corn oil and applied to the cell cultures for intervals up to 6 hours and frequencies measured at intervals of 15 minutes to 1 hour. Benomyl and butyl isocyanate caused concentration‐dependent decreases in ciliary beat frequency. Benomyl at 300 μg/ml (3 mM) caused ciliostasis within 75 minutes of exposure. Butyl isocyanate at a molar concentration three times lower than benomyl (1 mM) caused a similar response, although within 30 minutes. The IBC₅₀ for benomyl was 0.75 mM, while for butyl isocyanate it was 0.52 mM. Carbendazim caused a moderate decrease in frequency over a 6 hour exposure period. Benomyl caused moderate to severe swelling of the mitochondria of ciliated epithelial cells with other cell organelles appearing normal. Butyl isocyanate did not cause any noticeable effect on cell ultrastructure and the apparently low rate of penetration of carbendazim into cells made it impossible to obtain an effect which justified ultrastructural analysis. It appears, at least for benomyl and butyl isocyanate, that while the physiological effect of these two compounds (inhibition of ciliary beat) is the same, the sites of action in the cell may be different.     

Effects of UV-A LED light irradiation on growth of cultured RAW 264.7 cells

The aim of this study was to examine the effects of ultraviolet A (UV-A) irradiation-induced damage on cultured macrophage RAW 264.7 cells and determine which components produced these manifestations. RAW 264.7 cells were irradiated with 365 nm UV-A using a light-emitting diode (LED). Cell viability and damage were determined using a calcein-AM and propidium iodide dual-staining assay and lactate dehydrogenase leakage, respectively. Intracellular reactive oxygen species (ROS) were measured by H₂DCF-DA. The components of ROS in each medium were measured using an electron paramagnetic resonance (EPR) spectrometer in the presence of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and 2,2,5,5-tetramethyl-3-pyrroline-3-carboxamide (TPC). While UV-A irradiation for 2 min significantly suppressed cell growth, LDH leakage did not occur. Addition of N-acetyl cysteine restored inhibition of cell proliferation, and reduced intracellular ROS levels. The EPR signal in the presence of TPC increased with time but was decreased by sodium azide. In addition, a typical EPR spectrum was obtained in the presence of DMPO, indicating the presence of a hydroxyradical. The spectrum was diminished by L-histidine. Data suggest that ROS generated in cells or culture medium by UV-A irradiation is predominantly singlet oxygen, and this singlet oxygen suppressed cell proliferation.     

Nanosilica exerts cytotoxicity and apoptotic response via oxidative stress in mouse embryonic fibroblasts

Nanoscale silica is an important industrial material and extensively used in medicines. The objective of this study was to determine potential cytotoxicity and genotoxic effects attributed to nanosilica exposure in mouse embryonic fibroblasts (L929) cells. Nanosilica produced mild cytotoxicity in L929 cells. Results showed that nanosilica increased thiobarbituric acid reactive substance levels and enhanced superoxide dismutase activity but decreased levels of glutathione. This was accompanied by a concomitant generation of reactive oxygen species, loss of mitochondrial membrane potential, and activation of caspase-3 activity. In addition, in the single-cell gel test, nanosilica (50–300 μg/ml) at two treatment times 24 and 48 hr produced concentration- and time-dependent increase of DNA damage. Therefore, the obtained results indicate that nanosilica may induce genotoxic effects in cultured L929 cells associated with induction of oxidative stress.     

Studying developmental neurotoxic effects of bisphenol A (BPA) using embryonic stem cells

There is little to no toxicity information regarding thousands of chemicals to which people are exposed daily. In fact, of the 84,000 chemicals listed in the United States Toxic Substances Control Act Inventory, there is limited information available on their effects on neural development (Betts, 2010 and US EPA, 2015). The number of chemicals tested remains low due to the high cost of conducting multi-generational animal studies and the lack of alternative testing methods.     

Assessment of Bisphenol A (BPA) neurotoxicity in vitro with mouse embryonic stem cells

The adverse effects of environmental pollution on our well-being have been intensively studied with many in vitro and in vivo systems. In our group, we focus on stem cell toxicology due to the multitude of embryonic stem cell (ESC) properties which can be exerted in toxicity assays. In fact, ESCs can differentiate in culture to mimic embryonic development in vivo, or specifically to virtually any kind of somatic cells. Here, we used the toxicant Bisphenol A (BPA), a chemical known as a hazard to infants and children, and showed that our stem cell toxicology system was able to efficiently recapitulate most of the toxic effects of BPA previously detected by in vitro system or animal tests. More precisely, we demonstrated that BPA affected the proper specification of germ layers during our in vitro mimicking of the embryonic development, as well as the establishment of neural ectoderm and neural progenitor cells.     

微生物燃料电池的研究综述

微生物燃料电池是一种利用微生物的催化作用,将燃料中的化学能转化为电能,同时又可以处理废水的新型技术,具有显著的环境效益和经济效益。本文对微生物燃料电池的基本原理进行了详细的叙述,对一些影响微生物燃料电池在处理污水时发电的基本因素做了较全面的比较,同时也探讨了一些现阶段微生物燃料电池的瓶颈问题。展望了微生物燃料电池(MFCs)这一绿色技术的良好的发展前景。     

Mitochondrial electron transport chain is involved in microcystin-RR induced tobacco BY-2 cells apoptosis

Microcystin-RR （MC-RR） has been suggested to induce apoptosis in tobacco BY-2 cells through mitochondrial dysfunction including the loss of mitochondrial membrane potential . TO further elucidate the mechanisms involved in MC-RR induced apoptosis in tobacco BY-2 cells, we have investigated the role of mitochondrial electron transport chain （ETC） as a potential source for reactive oxygen species （ROS）. Tobacco BY-2 cells after exposure to MC-RR （60 mg/L） displayed apoptotic changes in association with an increased production of ROS and loss of Am. All of these adverse effects were significantly attenuated by ETC inhibitors including Rotenone （2 μmol/L, complex I inhibitor） and antimycin A （0.01 μmol/L, complex III inhibitor）, but not by thenoyltrifluoroacetone （S μmol/L, complex Ⅱinhibitor）. These results suggest that rnitochondrial ETC plays a key role in mediating MC-RR induced apoptosis in tobacco BY-2 cells through an increased mitochondrial production of ROS.