Atmospheric HULIS and its ability to mediate the reactive oxygen species (ROS): A review

Atmospheric humic-like substances(HULIS) are not only an unresolved mixture of macroorganic compounds but also powerful chelating agents in atmospheric particulate matters(PMs); impacting on both the properties of aerosol particles and health effects by generating reactive oxygen species(ROS). Currently, the interests of HULIS are intensively shifting to the investigations of HULIS-metal synergic effects and kinetics modeling studies, as well as the development of HULIS quantification, findings of possible HULIS sources and generation of ROS from HULIS. In light of HULIS studies, we comprehensively review the current knowledge of isolation and physicochemical characterization of HULIS from atmospheric samples as well as HULIS properties(hygroscopic, surface activity, and colloidal) and possible sources of HULIS.This review mainly highlights the generation of reactive oxygen species(ROS) from PMs, HULIS and transition metals, especially iron. This review also summarized the mechanism of ironorganic complexation and recent findings of OH formation from HULIS-metal complexes. This review will be helpful to carry out the modeling studies that concern with HULIS-transition metals and for further studies in the generation of ROS from HULIS-metal complexes.     

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.     

Determination of photochemically-generated reactive oxygen species (ROS) in natural water

Reactive oxygen species (ROS) can be produced by interactions between sunlight and light-absorbing substances in natural water environment. ROS may participate in the indirect photolysis of trace organic pollutants, therefore resulting in the changing of their environmental fates and ecological risks in natural water system. Bisphenol A (BPA), an endocrine-disrupting chemical, exits widely in natural water. The photodegradation of BPA promoted by ROS (·OH, 1O2, HO2·/O2·-) which were produced on the excitation of ubiquitous constituents (such as nitrate ion, humic substances and Fe(III)-oxalate complexes) in natural water under simulated solar radiation was investigated. Both molecular probe method and electron spin resonance (ESR) test were used for the determine the characterization of generated ROS. It was found that ·OH was photochemically produced with the presence of nitrate ion, humic substances and Fe(III)-oxalate complexes and 1O2 was produced with the presence of humic substances. The steady-state concentrations of ·OH was 1.27×10-14 mol/L in nitrate ion, and the second-order rate constant of BPA with ·OH was 1.01×1010L/( mol·s).     

几种重金属对皱纹盘鲍血细活性氧产生的影响

体外条件下利用化学发光法定量地研究了不同种类和不同浓度的重金属:Cr、Cd、Hg、Pb、C和Zn对皱纹盘鲍血细胞吞噬时活性氧产生的影响。结果表明,不同种类和不同浓度的重金属浸泡急性处理皱纹盘鲍血细胞都不同程度地抑制了血细胞吞噬时的化学发光,表明重金属能够抑制皱纹盘鲍血细胞吞噬活动中的活性氧(ROS)的产生,而且这种抑制作用随着重金属浓度的增加而加强。不同的重金属抑制强度不同,从强到弱以次为Hg>Cd>Cu>Pb>Cr>Zn。研究表明六种重金属中,Hg对皱纹盘鲍血细胞的免疫毒性最大。     

Molecular toxicity and defense mechanisms induced by silver nanoparticles in Drosophila melanogaster

The widely use of silver nanoparticles (AgNPs) as antimicrobial agents gives rise to potential environmental risks. AgNPs exposure have been reported to cause toxicity in animals. Nevertheless, the known mechanisms of AgNPs toxicity are still limited. In this study, we systematically investigated the toxicity of AgNPs exposure using Drosophila melanogaster. We show here that AgNPs significantly decreased Drosophila fecundity, the third-instar larvae weight and rates of pupation and eclosion in a dose-dependent manner. AgNPs reduced fat body cell viability in MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assays. AgNPs caused DNA damage in hemocytes and S2 cells. Interestingly, the mRNA levels of the entire metallothionein gene family were increased under AgNPs exposure as determined by RNA-seq analysis and validated by qRT-PCR, indicating that Drosophila responded to the metal toxicity of AgNPs by producing metallothioneins for detoxification. These findings provide a better understanding of the mechanisms of AgNPs toxicity and may provide clues to effect on other organisms, including humans.     

Titanium nanoparticles attenuates arsenic toxicity by up-regulating expressions of defensive genes in Vigna radiata L

Arsenic(As)-toxicity is recognized as one of the major environmental problems,affecting productivity of crops worldwide,thereby threatening sustainable agriculture and food security.Progression in nanotechnology and its impacts have brought up concerns about the application of engineered nanoparticles(NPs) in various sectors of the economy,including the field of agronomy.Among various NPs,there has been a rising amount of interest regarding the effects of titanium NPs(TiNPs) on plants growth and development,and their fate of abiotic stress tolerance.Hence,the present study was aimed to assess the ameliorative potentialities of chemically and biologically/green synthesized TiNPs to alleviate As-induced toxic responses in Vigna radiata L.The results revealed that exposure to As hindered the growth indices(radicle length and biomass) and membrane integrity,while were improved with the application of chemical and green synthesized TiNPs.In addition,treatment of As provoked the accretion of reactive oxygen species(superoxide and hydrogen peroxide) and malondialdehyde(a lipid per oxidized product),but were diminished by the supplementation of chemical and green manufactured TiNPs.The experimental data also signified that exogenous application of chemical and green synthesized TiNPs conferred tolerance to As-induced oxidative injuries via perking-up the expressions of antioxidant genes and enzyme systems viz;superoxide dismutase and catalase.Therefore,the present study inferred that chemically and green synthesized TiNPs,particularly green manufactured,effectively mitigated the adverse impacts of As by augmenting antioxidant machinery,thereby proving its potentiality in the alleviation of As-toxicity,at least in Vignaradiata L.     

Effects of nitrogen dioxide and its acid mist on reactive oxygen species production and antioxidant enzyme activity in Arabidopsis plants

Nitrogen dioxide (NO₂) is one of the most common and harmful air pollutants. To analyze the response of plants to NO₂ stress, we investigated the morphological change, reactive oxygen species (ROS) production and antioxidant enzyme activity in Arabidopsis thaliana (Col-0) exposed to 1.7, 4, 8.5, and 18.8 mg/m³ NO₂. The results indicate that NO₂ exposure affected plant growth and chlorophyll (Chl) content, and increased oxygen free radical (O₂⁻) production rate in Arabidopsis shoots. Furthermore, NO₂ elevated the levels of lipid peroxidation and protein oxidation, accompanied by the induction of antioxidant enzyme activities and change of ascorbate (AsA) and glutathione (GSH) contents. Following this, we mimicked nitric acid mist under experimental conditions, and confirmed the antioxidant mechanism of the plant to the stress. Our results imply that NO₂ and its acid mist caused pollution risk to plant systems. During the process, increased ROS acted as a signal to induce a defense response, and antioxidant status played an important role in plant protection against NO₂/nitric acid mist-caused oxidative damage.     

Oxidative stress and apoptosis of Carassius auratus lymphocytes induced by nonplanar （PCB153） and coplanar （PCB169） polychlorinated biphenyl congeners in vitro

Among all the 209 kinds of polychlorinated biphenyls (PCBs) congeners, nonplanar and coplanar PCB congeners have di erent levels of toxicity on mammal cells such as neuronal cells, but little is known about their toxicity on fish cells although PCB congeners usually have high bioaccumulation abilities in the detected fish bodies. This study showed that 2,2’,4,4’,5,5’-hexacholorbiphenyl (PCB153, nonplanar congener) and 3,3’,4,4’,5,5’-hexacholorbiphenyl (PCB169, coplanar congener) caused apoptosis on the isolated crucian carp (Carassius auratus) lymphocytes and the induced cytotoxicity was structure-dependent. According to the laser confocal microscope observations, apoptosis was clearly distinguished by condensation of nucleus, shrinkage and formation of apoptotic bodies. DNA fragmentation was detected by agarose gel electrophoresis. These typical morphological and biochemical characteristics indicate the occurrence of apoptosis on fish lymphocytes. According to the flow cytometry analysis, after the cells were exposed to 10 mol/L PCBs for 3 h, the apoptotic percentage induced by PCB153 was 23.41%, while that induced by PCB169 was even higher (31.03%). Furthermore, incubating PCBs with fish lymphocytes enhanced levels of reactive oxygen species (ROS) and malondialdehyde (MDA), clearly indicating the presence of oxidative stress and lipid peroxidation. Our data also demonstrate that the di erent cytotoxic e ects induced by coplanar and nonplanar PCBs were correlated with their structural characteristics and the coplanar congener was more cytotoxic than nonplanar congener. This study suggests that cytotoxicity mechanisms of the PCB congeners on fish lymphocytes depend on their planarity and chemical structures.     

Abnormal energy metabolism and tau phosphorylation in the brains of middle-aged mice in response to atmospheric PM2.5 exposure

In light of the accelerated aging of the global population and the deterioration of the atmosphere pollution, we sought to clarify the potential mechanisms by which fine particulate matter (PM_2.5) can cause cognitive impairment and neurodegeneration through the alteration of mitochondrial structure and function. The results indicate that PM_2.5 inhalation reduces ATP production by disrupting the aerobic tricarboxylic acid cycle and oxidative phosphorylation, thereby causing the hypophosphorylation of tau in the cortices of middle-aged mice. Furthermore, excessive reactive oxygen species generation was involved in the impairment. Interestingly, these alterations were partially reversed after exposure to PM_2.5 ended. These findings clarify the mechanism involved in mitochondrial abnormality-related neuropathological dysfunction in response to atmospheric PM_2.5 inhalation and provide an optimistic sight for alleviating the adverse health outcomes in polluted areas.     

西安市重污染与清洁天PM2.5组分及其活性氧物质对比

针对重霾污染,在西安市冬季重污染日(2015-11-30~2015-12-09)和清洁日(2016-01-13~2016-01-22)各进行了为期10d的PM_(2.5)采集,测量其中的有机碳、元素碳,及NH_4~+、NO_3~-、SO_4~(2-)等无机水溶性离子,探讨两种污染条件下的组分特征及其成因.结果表明:观测期,重霾日和清洁日PM_(2.5)质量浓度分别为(170±47.5)μg·m~(-3)和(48.6±17.9)μg·m~(-3),且重霾日伴随低能见度、高湿静风等多种不利气象条件;重霾日二次无机离子(NH_4~+、NO_3~-、SO_4~(2-))组分占PM_(2.5)质量浓度的49.8%±13.1%,而清洁日为19.4%±5.95%,并且重霾日硫氧化速率(sulfur oxidation ratio,SOR)和氮氧化速率(nitrogen oxidation ratio,NOR)分别为0.282±0.157和0.269±0.124,远高于清洁日(SOR和NOR分别为0.189±0.057和0.077±0.046),重霾日二次有机组分浓度[(6.22±3.87)μg·m~(-3)]是清洁日[(1.44±1.63)μg·m~(-3)]的5倍,表明二次污染及不利气象条件是造成重霾期间相关组分浓度升高的重要原因.最后,通过二氯荧光黄双乙酸盐(2',7'-DCFH)化学荧光分析法测定了其中活性氧物质(reactive oxygen species,ROS)的浓度,探讨其对于二次无机组分形成的影响,结果表明观测期ROS平均浓度(以H_2O_2计)分别为(4.99±1.54)nmol·m~(-3)(重霾期),(0.492±0.356)nmol·m~(-3)(清洁期),二次反应及积累效应可能是西安重霾条件下ROS浓度升高的主要原因.NO_3~-、SO_4~(2-)与ROS均呈现正相关(P0.05),表明ROS可能通过二次氧化过程参与到二次无机组分形成过程中.