Acute Toxicity Tests with Cadmium,Lead, Sodium Dodecyl Sulfate,and Bacillus thuringiensis on a Temporary Pond Ostracod

A complete assessment of effects of pollutants in the environment requires the use of a wide assemblage of test organisms. Crustaceans have been widely used in aquatic environments, but within this group, ostracods have been overlooked, even though they are one of the commonest groups of animals in temporary waters. Within this framework, static acute toxicity bioassays were conducted with heavy metals Cd and Pb, the surfactant SDS and spores of the bacteria Bacillus thuringiensis var. israeliensis using adult parthenogenetic females of the temporary pond ostracod Heterocypris bosniaca. Experiments were run at 20 °C and in a 12 by 12 h photoperiod. The toxicity tests results are expressed as LC₅₀ and EC₅₀ at 48 h and 96 h using probit analysis. The sensitivity of H. bosniaca at 48 h decreased in the following order Cd > Pb > SDS > Bti, while Pb and SDS exchanged their positions at 96 h. Comparison of the LC₅₀ values for this species with information available in the literature reveals that it is generally more resistant than other crustaceans. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Interactions of lichens with heavy metals

Recent developments in knowledge about the interactions between lichens and heavy metals at different levels, from populations to cells and from ecology to molecular biology are reviewed. Sources of heavy metals, mechanisms of heavy metal accumulation and detoxification by lichens are discussed. Special emphasis is placed on ultrastructural changes as well as physiological parameters such as membrane integrity, pigment composition, chlorophyll a fluorescence, photosynthesis, respiration, contents of ATP, amino acids, ergosterol, ethylene, non-protein thiols, activity of antioxidant enzymes and expression of stress proteins.     

The Eco-efficiency of Lead in China's Lead-Acid Battery System

Improving eco-efficiency can contribute to sustainable development. This article defines the societal services and environmental impacts of the lead-acid battery (LAB) system and offers definitions of eco-efficiency, resource efficiency, and environmental efficiency in the context of LAB systems. Based on the actual lead-flow in the LAB system, we develop a model that considers changes in production, the time interval between production and disposal, direct linkages between the final product and the societal service it provides, and the fiscal year as the statistical period. From this model, equations for eco-efficiency are derived and changes in eco-efficiency are predicted.
The results show, not surprisingly, that increased lead recycling and reduced lead emissions will both improve ecoefficiency. The resource and environmental efficiencies for LAB in China are 119 and 131 kilowatt-hour-years per metric tonne (kWh. yr/t), respectively, versus a value for both of 15, 800 kWh. yr/t in Sweden. The difference results from a lower lead recycling rate (only 0.312 tonne/tonne, which means that nearly 70% of the old lead scrap is not recycled based on official statistics) and higher lead emissions (0.324 tonne/tonne, which means that nearly 33% of the lead inputs used in the LAB system were lost into the environment) in China. Further analysis shows that these problems result from inefficient management of lead scrap, poor quality lead ore, and an abundance of small-scale lead-related plants. Ways to improve eco-efficiency are proposed.     

The role of root damage in the chelate-enhanced accumulation of lead by Indian mustard plants

In the present study, increasing ethylenediaminetetraacetic acid (EDTA) concentration from 0 to 0.5 mmol L(-1) resulted in progressive increases in root elongation and in shoot and root dry matter (DM) of Indian mustard seedlings (Brassica juncea. L.) exposed at 0.5 mmol L(-1) of lead (Pb). The highest concentration of Pb in the shoots of Indian mustard reached 1140 mg kg(-1) dry weight (DW) in the treatment with 0.5 mmol L(-1) of Pb + 0.25 mmol L(-1) of EDTA. A significantly positive correlation was found between the concentrations of Pb and EDTA in the shoots of mustard. Roots were pretreated with an MC (methanol:trichloromethane) solution, 0.1 mol L(-1) of HCl, and 65 degrees C hot water. The plants were then exposed to 0.5 mmol L(-1) of Pb + 3 mmol L(-1) of EDTA in solution for 2 d. The pretreatments with MC, HCl, and hot water all increased the concentration of Pb in shoots by 14-, 7-, and 15-fold, respectively, compared with the shoots that had not been pretreated. Therefore, some physiological damage to roots would be useful to enhance the uptake of metal by plants and to minimize the application of doses of chelates in the practical operation of chelate-assisted phytoremediation.     

生物电子等排原理在药物先导化合物优化中的应用

先导化合物的优化是新药研究和开发的重要环节。由于先导化合物只提供一种具有特定药理作用的新结构类型,往往由于在药理、药效学、药代动力学等方面的缺点或不足而不能直接用于临床。因此,需要对先导化合物进行进一步化学结构改造或修饰,以期优化上述特性。“生物电子等排取代(bioisostericreplacement)”即为对先导化合物进行合理优化的有效策略之一。本文简要综述了生物电子等排原理在药物先导化合物优化中的应用。     

Determination of lead content in medicinal plants by pre‐concentration flow injection analysis–flame atomic absorption spectrometry

Introduction – Although medicinal plants are widely used throughout the world, few studies have been carried out concerning the levels of heavy metal contaminants present. Such metals are highly toxic to living organisms even in low concentrations owing to their cumulative effect. The present paper describes the the development of a pre‐concentration flow injection analysis‐flame atomic absorption spectrometric system to determine the lead content in medicinal plants at the ppb level. Objective – To develop a pre‐concentration flow injection analysis‐flame atomic absorption spectrometric system to determine the lead content in medicinal plants at the ppb level. Methodology – A pre‐concentration flow system was coupled to a flame atomic absorption spectrometer. The plant samples were analysed after nitroperchloric digestion. The proposed system was optimised by evaluating the following parameters: nature, concentration and volume of the eluent solution, elution flow rate, elution efficiency, pre‐concentration flow rate and pre‐concentration time. Results – The proposed system exhibited good performance with high precision and repeatability (RSD ≤ 2.36%), excellent linearity (r = 0.9999), low sample consumption (10.5 mL per determination) and an analytical throughput of 55 samples/h. Lead concentrations ranged from 3.37 ± 0.25 to 7.03 ± 0.51 μg/g in dry material. This concentration interval is greater than that previously published in the literature. Conclusion – The inclusion of a pre‐concentration column in the flow manifold improved the sensitivity of the spectrometer. Thus, it was possible to determine the analyte at the ng/mL level in sample solutions of medicinal plants. This is a very important accomplishment, especially when the cumulative effect of heavy metals in living organisms is considered. Copyright © 2009 John Wiley & Sons, Ltd.     

Health Risks of Heavy Metals through Consumption of Greenhouse Vegetables Grown in Central Iran

Elevated heavy metal (HM) concentrations in vegetables may pose serious health risks to humans. There is limited information on health risks associated with HM contaminants in greenhouse vegetables. The objective of this study was to estimate the health risks of Pb, Cd, Ni, and Cr via consumption of greenhouse cucumbers and bell peppers produced in Iran using the total non-cancer hazard quotient (THQ) and cancer risk assessment estimates. Cadmium, Pb, Ni, and Cr concentrations in the vegetables varied from < 0.02 to 0.05, 0.19 to 0.64, 0.16 to 0.20 and 0.07 to 0.13 μg g^?1, respectively. Individual metal THQ values indicate the relative absence of non-cancer health effects associated with intake of a single metal through consumption of either cucumbers or bell peppers. The THQ for all population groups via consumption of greenhouse cucumbers and bell peppers was smaller than 1.0, which shows low possibility of any obvious risk. The result showed that Cd is the major risk contributor for the consumers. The cancer risk assessment for Pb for Qom adult populations groups via consumption of cucumbers and bell peppers was greater than 1 × 10^?6. High Pb and Cd concentration in the greenhouse vegetables is an important concern that has to be considered.     

一种新的铅富集植物--富集生态型东南景天

对浙江一古老铅锌矿区的土壤和植物种群进行调查后发现一种新的具有耐铅特性和铅富集能力的植物--景天科景天属东南景天(Sedum alfredii Hance),称为铅富集生态型植物.进一步比较和分析了不同浓度硝酸铅处理对富集和非富集生态型东南景天的生长及其对铅的吸收特性的影响.结果表明, 320 mg Pb/L处理对富集生态型的地上部分生长无显著影响,而非富集生态型在20 mg Pb/L时即出现受害症状.富集和非富集生态型的地上部分铅含量、根系铅含量以及单株铅积累速率均随处理浓度的增加而表现出先升后降的变化趋势.其中富集生态型的地上部分铅含量、根系铅含量以及单株铅积累速率最高可达到514 mg/kg、13 922 mg/kg和8.62 μg/plant/d,分别是非富集生态型的2.27、2.62和7.16倍.由于具有生长速度快和高积累铅的能力,从植物修复的观点来说,东南景天铅富集生态型在铅污染土壤的修复方面具有巨大的潜力.     

Acacia nilotica L. Bark Removes Toxic Elements from Solution: Corroboration from Toxicity Bioassay Using Salix viminalis L. in Hydroponic System

The present investigation deals with the advantages and potential of the Acacia nilotica bark as an adsorbent of toxic metals. Bark (1 g) when added to 100 ml of aqueous solution containing 10 μg ml^-1 metal solution exhibited different metal adsorption values for different metals. The order of metal adsorption being Cr ≥ Ni > Cu > Cd > As > Pb. A similar trend of metal adsorption was observed when the bark is reused (1^st recycle) Cr> Ni > Cu > Cd > Pb and also in the column sorption. In order to verify the metal removal property of A. nilotica bark, toxicity bioassay with Salix viminalis stem cuttings in hydroponic system augmented with Cd, Cr, and Pb together with A. nilotica bark powder was carried out. The results of toxicity bioassay confirmed the metal adsorption property of the bark powder. The functions of toxicity studies include leaf area, root length and number of new root primordia produced per stump. The leaf area, root length, and the number of new root primordia increased considerably in the presence of A. nilotica bark. The order of metal toxicity for leaf area and new root primordial is Cd > Cr > Pb. However, for root length the order of metal toxicity is Cr > Cd > Pb. The metal budgets of the leaf and root confirmed that the bark powder had adsorbed substantial amount of toxic metals and thus alleviates the toxicity imposed by the various tested elements. Hence, the utility of A. nilotica bark in developing and designing innovative technology for the clean up of toxic elements in aqueous solutions and possible scope for its use in phytoremediation are discussed.     

Structural analysis of protein‐ligand interactions: the binding of endogenous compounds and of synthetic drugs

The large number of macromolecular structures deposited with the Protein Data Bank (PDB) describing complexes between proteins and either physiological compounds or synthetic drugs made it possible a systematic analysis of the interactions occurring between proteins and their ligands. In this work, the binding pockets of about 4000 PDB protein‐ligand complexes were investigated and amino acid and interaction types were analyzed. The residues observed with lowest frequency in protein sequences, Trp, His, Met, Tyr, and Phe, turned out to be the most abundant in binding pockets. Significant differences between drug‐like and physiological compounds were found. On average, physiological compounds establish with respect to drugs about twice as many hydrogen bonds with protein atoms, whereas drugs rely more on hydrophobic interactions to establish target selectivity. The large number of PDB structures describing homologous proteins in complex with the same ligand made it possible to analyze the conservation of binding pocket residues among homologous protein structures bound to the same ligand, showing that Gly, Glu, Arg, Asp, His, and Thr are more conserved than other amino acids. Also in the cases in which the same ligand is bound to unrelated proteins, the binding pockets showed significant conservation in the residue types. In this case, the probability of co‐occurrence of the same amino acid type in the binding pockets could be up to thirteen times higher than that expected on a random basis. The trends identified in this study may provide an useful guideline in the process of drug design and lead optimization. Copyright © 2014 John Wiley & Sons, Ltd.