PCDD/Fs-induced oxidative damage and antioxidant system responses in tobacco cell suspension cultures

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) are ubiquitous contaminants and can be considerably accumulated by natural plants. In order to elucidate the biochemical and physiological responses of plant to PCDD/Fs, tobacco Bright Yellow-2 (BY-2) cells were selected as model plant and treated with time- and concentration-dependent PCDD/Fs. The toxic effect and oxidative stress caused by PCDD/Fs were evident, which could be indicted by the reduction in fresh mass, the increase in malondialdehyde (MDA) content, and the damage of tobacco cell ultrastructure. PCDD/Fs tolerance was correlated with changes in antioxidant system and hormones of tobacco cells. Superoxide dismutase (SOD) and peroxidase (POD) exhibited peak enzyme activities at the PCDD/Fs concentration of 1000 ng WHO₉₈-TEQ g⁻¹ fresh weight. Glutathione reductase (GR) enzyme activity increased monotonically at high level PCDD/Fs, but the activity of catalase (CAT) was only slightly affected at all treatment. Meanwhile, the exposure to PCDD/Fs resulted in the changes of hormones content. With the increase of exposure concentration of PCDD/Fs, the levels of indole-3-acetic acid (IAA) and abscisic acid (ABA) increased, whereas the concentration of jasmonates (JAs) decreased. The above results suggest that tobacco cells had the ability to cope with the oxidative stress induced by low concentration of PCDD/Fs through increasing the activities of antioxidant enzymes and alternating plant hormones levels. However, oxidative stress and toxicity would burst out when plant cells were exposed to the high levels of PCDD/Fs.     

Estimating receptor sensitivity to spatial proximity of emissions sources

Spatial proximity of emissions sources to receptors may affect sensitivity to potential adverse human health effects. This research investigates whether receptor sensitivity to the location of emission sources can be utilized efficiently to minimize health risk in selecting sites for industrial enterprises, thermal electric stations, etc. A sensitivity function that is independent of the location of pre-existing emission sources is derived and applied to Minsk, Belarus. The function estimates exposures based on weather and climatic conditions as well as the distribution of population density at a given locality. Arraying prospective sites based on their sensitivity function magnitude provides a technique for minimizing health risk based on receptor sensitivity to the spatial proximity of atmospheric emissions sources.     

Reliability of Indicators of Decline in Abundance

Abstract: Although there are many indicators of endangerment (i.e., whether populations or species meet criteria that justify conservation action), their reliability has rarely been tested. Such indicators may fail to identify that a population or species meets criteria for conservation action (false negative) or may incorrectly show that such criteria have been met (false positive). To quantify the rate of both types of error for 20 commonly used indicators of declining abundance (threat indicators), we used receiver operating characteristic curves derived from historical (1938–2007) data for 18 sockeye salmon (Oncorhynchus nerka) populations in the Fraser River, British Columbia, Canada. We retrospectively determined each population's yearly status (reflected by change in abundance over time) on the basis of each indicator. We then compared that population's status in a given year with the status in subsequent years (determined by the magnitude of decline in abundance across those years). For each sockeye population, we calculated how often each indicator of past status matched subsequent status. No single threat indicator provided error‐free estimates of status, but indicators that reflected the extent (i.e., magnitude) of past decline in abundance (through comparison of current abundance with some historical baseline abundance) tended to better reflect status in subsequent years than the rate of decline over the previous 3 generations (a widely used indicator). We recommend that when possible, the reliability of various threat indicators be evaluated with empirical analyses before such indicators are used to determine the need for conservation action. These indicators should include estimates from the entire data set to take into account a historical baseline.     

Source apportionment studies for particulates (PM10) in Kozhikode,South Western India using a combined receptor model

In the present work, source apportionment studies were carried out for particulate matter – one among the significant pollutants as addressed by The National Ambient Air Quality Standards. Advantages and disadvantages of each receptor model were addressed using a combined receptor model which integrates Factor Analysis (FA), Positive Matrix Factorisation (PMF) and Chemical Mass Balance (CMB). Verification of the approach was done using sets of synthetic data as well as field data from Kozhikode. Sampling was carried out in National Institute of Technology, Calicut for a period of over 26 days with 24-hour sampling. The sampling gave an average PM concentration value in the range of 29.174–129.176 µg m^?3. Studies using field data revealed five dominant sources and their contributions obtained from CMB and PMF were compared. Soil dust (contribution from CMB: 18%; contribution from PMF: 16%), marine aerosol (17%; 25%), construction and aggregate processing (46%; 11%), garden waste combustion (18%; 45%), and vehicular exhaust (1%; 3%) were major contributors in the site under study. The outcomes of the study integrated with the support of local authorities and by the acceptance of residents can definitely curb the pollution levels in the site under the study.     

A study on the effect of deoxynivalenol on serotonin receptor binding in fig brain membranes

Abstract

Central serotoninergic (5‐hydroxytryptamine, 5HT) pathways are believed to be involved in the mechanisms of anorexia and/or emesis evoked by the trichothecene mycotoxin deoxynivalenol (DON). Using an in vitro membrane receptor binding assay, the competitive potency of DON was investigated against several radioactive ligands that have a high affinity for selective 5HT‐receptor subgroups. Receptor site densities and displacement profiles in twelve selected regions of pig brain were investigated. Overall, DON possessed only minimal efficacy to competently block any of the 5HT‐ligands tested. IC₅₀ values (50% inhibitory concentration) of at least 5 mM DON were required to inhibit binding, and in certain regions concentrations of 100 mM were ineffective. In comparison, several standard 5HT‐antagonists showed 10³‐10⁵ times greater capability than DON to displace binding of these ligands. Because these results indicated DON possesses only weak affinity for the 5HT‐receptor subtypes investigated here, this suggested that in vivo, unless relatively high concentrations of the toxin are present, its pharmacological effects may be mediated by mechanisms other than a functional interaction with serotoninergic receptors at the central level.     

Assays of PCB congeners and organochlorine insecticides with the transgenic Arabidopsis and tobacco plants carrying recombinant guinea pig AhR and GUS reporter genes

Certain congeners of polychlorinated biphenyls (PCBs) and organochlorine insecticides are ligands of aryl hydrocarbon receptors (AhRs) in animals. A recombinant guinea pig (g) AhR, XgDV, was constructed by fusing the ligand-binding domain of gAhR, the DNA-binding domain of LexA, and the transactivating domain of VP16. Then, the expression unit of β-glucuronidase (GUS) reporter gene regulated by XgDV was introduced into Arabidopsis and tobacco plants. When the transgenic Arabidopsis XgDV plants were cultured on Murashige–Skoog (MS) medium containing PCB congeners, the GUS activity in the plants increased toxic equivalent (TEQ)-dependently. The GUS activity in the transgenic Arabidopsis XgDV plants cultured on MS medium containing the organochlorine insecticide dieldrin was also induced. On the other hand, in the case of DDT, the GUS activity induced by 3-methylcholanthere in the plants decreased. The transgenic Arabidopsis XgDV plants detected 1000 ng g^?1 PCB126 in 1 g of soils. Thus the XgDV plants seemed to be useful for convenient assays of PCB congeners and organochlorine insecticides, without any extraction and purification steps.     

基于APCS-MLR受体模型的弹药销毁场土壤重金属源解析

为了掌握弹药销毁场重金属污染状况与来源,以山西某典型弹药销毁场为例,对该销毁场39个表层土壤重金属（Cr、Ni、Cu、Zn、As、Cd、Sb、Pb）的污染状况、分布特征与污染来源进行评价与分析. 结果表明,弹壳堆放区表层土壤重金属Cr、Ni、Cu、Zn、As、Cd、Sb、Pb的平均含量分别为45.57、23.43、325.54、265.43、9.53、0.42、304.17、13174.29 mg·kg⁻¹,其余区域表层土壤重金属Cr、Ni、Cu、Zn、As、Cd、Sb、Pb的平均含量分别为102.09、26.75、1137.18、3007.13、7.71、0.95、70.65、2894.97 mg·kg⁻¹,均高于山西省背景值. 污染指数评价结果表明,Pb、Zn、Cu、Sb和Cd的累积程度较高. 研究区土壤重金属生态危害指数为2653.35,达到极高生态风险水平. 绝对主成分得分-多元线性回归模型(APCS-MLR)表明,Ni、Cd、Zn、Cr和Cu的来源主要为混合源,贡献率为72.94%,Pb和Sb的主要来源是销毁源,贡献率为53.99%,自然源对As贡献率最大,为44.63%.     

不同湿度条件下甲醛暴露致大鼠认知功能损伤及毒理学机制研究

探讨不同湿度条件下甲醛暴露对大鼠认知功能的影响及毒理学机制.取SPF级6～8周龄雌性SD大鼠48只,随机分为6组:对照组(Control组)、甲醛组(FA组)、低湿度组(60％Hum组)、中湿度组(75％Hum组)、高湿度组(90％Hum组)和高湿度联合甲醛组(90％Hum+FA组).不同湿度组分别置于(60％/75％/90％)环境仓中暴露,FA组采用职业气态方式暴露(3 mg·m-3,8 h·d-1,5 d·周-1),连续21 d后观察Morris水迷宫和旷场实验结果,苏木精-伊红染色法(HE)、尼氏染色观察各组大鼠海马神经元的形态学变化,免疫荧光法和免疫印迹实验(Western Blot)检测瞬时受体电位香草素受体4(TRPV4)、闭合蛋白(Occlu-din)和紧密连接蛋白5(Claudin-5)的蛋白表达水平.与Control组相比,不同湿度组和FA组大鼠的认知功能下降,海马神经元数量减少,且随湿度升高而加剧(P＜0.05);与FA组、90％Hum组分别比较,90％Hum+FA组认知功能和海马神经元损伤加剧,且TRPV4表达升高,Occludin和Claudin-5表达降低,差异具有统计学意义(P＜0.05).高湿度和甲醛联合暴露可能通过激活TRPV4离子通道,下调Occludin和Claudin-5表达,加剧大鼠海马神经元的损伤,使认知功能进一步下降.     

内分泌干扰物与哺乳动物核受体的相互作用

内分泌干扰物(EDCs)作用于哺乳动物生殖轴或甲状腺轴,影响生长、发育、繁殖、免疫等生理过程并诱发疾病。核受体介导途径是EDCs发挥内分泌干扰作用的最重要方式。在介绍EDCs对哺乳动物的毒性效应与机制的基础上,详细归纳了EDCs与核受体的相互作用,并总结了这一研究领域适用的研究方法。发现采用理论计算模拟、表面等离子共振、荧光偏振、细胞增殖、报告基因等技术方法,目前已经明确了邻苯二甲酸酯类、双酚类、有机氯农药等EDCs能够竞争结合雌激素受体、雄激素受体和/或甲状腺激素受体,以此为作用靶点通过受体介导途径发挥内分泌干扰效应。基于目前的研究现状,我们认为未来的研究应更加注重EDCs与孕激素受体及维甲酸受体的相互作用、膜受体介导途径以及体内实验与体外实验的有机结合。