Enhanced resistance of yeast mutants deficient in low-affinity iron and zinc transporters to stannous-induced toxicity

Tin or stannous (Sn²⁺) compounds are used as catalysts, stabilizers in plastic industries, wood preservatives, agricultural biocides and nuclear medicine. In order to verify the Sn²⁺ up-take and toxicity in yeast cells we utilized a multi-elemental analysis known as particle-induced X-ray emission (PIXE) along with cell survival assays and quantitative real-time PCR. The detection of Sn²⁺ by PIXE was possible only in yeast cells in stationary phase of growth (STAT cells) that survive at 25 mM Sn²⁺ concentration. Yeast cells in exponential phase of growth (LOG cells) tolerate only micro-molar Sn²⁺ concentrations that result in intracellular concentration below of the method detection limit. Our PIXE analysis showed that STAT XV185-14c yeast cells demonstrate a significant loss of intracellular elements such as Mg, Zn, S, Fe and an increase in P levels after 1 h exposure to SnCl₂. The survival assay showed enhanced tolerance of LOG yeast cells lacking the low-affinity iron and zinc transporters to stannous treatment, suggesting the possible involvement in Sn²⁺ uptake. Moreover, our qRT-PCR data showed that Sn²⁺ treatment could generate reactive oxygen species as it induces activation of many stress-response genes, including SOD1, YAP1, and APN1.     

Natural attenuation is enhanced in previously contaminated and coniferous forest soils

Purpose  

Prevalence of organic pollutants or their natural analogs in soil is often assumed to lead to adaptation in the bacterial community, which results in enhanced bioremediation if the soil is later contaminated. In this study, the effects of soil type and contamination history on diesel oil degradation and bacterial adaptation were studied.     

From the outside in: The negative spillover effects of boundary spanners' relations with members of other organizations

Contrary to much boundary spanning research, we examined the negative consequences of boundary spanning contact in multi‐organizational contexts. Results from a sample of 833 Dutch peacekeepers show that employees' boundary spanning contact with members of other organizations was associated with reports of negative relationships with external parties (e.g., work‐specific problems, culture‐specific problems). These negative relationships also had a spillover effect such that they mediated the effect of boundary spanning contact on boundary spanners' negative attitudes toward their own jobs and organization (e.g., job attractiveness and confidence in the organization). Copyright © 2010 John Wiley & Sons, Ltd.     

The historical record of PCB and PCDD/F deposition at Greifensee, a lake of the Swiss plateau, between 1848 and 1999

Dated sediment cores provide an excellent way to investigate the historical input of persistent organic pollutants into the environment and to identify possible sources of pollution. The vertical distribution of polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/F) and polychlorinated biphenyls (PCB) was investigated in a sediment core from Greifensee to elucidate the historical trends of PCDD/F and PCB inputs between 1848 and 1999. Concentrations of PCB and PCDD/F increased by more than one order of magnitude between 1930 and 1960. PCB and PCDD/F concentrations were 5700 ng/kg dry weight (dw) and 160 ng/kg dw, respectively, in sediments originating from the late 1930s and reached a maximum of 130,000 ng/kg dw and 2400 ng/kg dw, respectively, in the early 1960s. From 1960 on, concentrations decreased to the 1930s level by the mid 1980s. A remarkable shift in the PCDD/F pattern was observed after the early 1940s. Before 1940, the PCDD/F pattern was PCDF dominated (ratio of PCDD to PCDF=0.41+/-0.11), while the PCDD started to be the major species after the early 1940s (ratio of PCDD to PCDF=1.46+/-0.38). The temporal trends of PCB and PCDD/F correlate surprisingly well with each other. This might be due to the coincidence of two factors. The introduction of PCB on the market in the 1930s resulted in emissions due to the widespread use of these industrial chemicals. In the same time period, waste incineration became an increasingly popular way to get rid of garbage, boosting the PCDD/F emissions significantly. The rapid decline of PCDD/F and PCB concentrations in the sediment starting in the early 1960s reflects the result of better emission control techniques in thermal processes and the improvement of waste water treatment in the catchment of Greifensee.     

Predatory insects as bioindicators of heavy metal pollution

Heavy metal concentrations of different predatory insects were studied near by a steel factory and from control sites. Waterstriders (Gerridae), dragon fly larvae (Odonata), antlion larvae (Myrmeleontidae) and ants (Formicidae) were analyzed by AAS. In most cases the metal concentrations were higher near the factory, but e.g. waterstriders had higher cadmium concentrations in control area. Discriminant analysis clearly reveals that all these insect groups can be used as heavy metal indicators. However, the commonly used ants were the least effective in indicating the differences between the factory and control sites. Waterstriders are good in detecting differences in iron and manganese, but seem to be poor in accumulating nickel and lead. Antlions are efficient in detecting differences in iron. Antlions and ants are effective in accumulating manganese; as well antlions are efficient in accumulating cadmium. Waterstriders are poor in accumulating lead, but antlions and ants are effective.     

Risk assessment of linear alkylbenzene sulphonates, LAS, in agricultural soil revisited: robust chronic toxicity tests for Folsomia candida (Collembola), Aporrectodea caliginosa (Oligochaeta) and Enchytraeus crypticus (Enchytraeidae)

To obtain robust data on the toxicity of LAS, tests with the collembolan Folsomia candida L., the oligochaetes Aporrectodea caliginosa Savigny (earthworm) and Enchytraeus crypticus Westheide and Graefe (enchytraeid) were performed in a sandy loam soil. Additionally limited tests with LAS spiked to sewage sludge, and subsequently mixed into soil, were performed. For the endpoint of interest, reproduction in soil, we found an EC10 of 205 mg LAS kg(-1) soil [8.6-401] [95% confidence limits] for F. candida and an EC10 of 46 mg LAS kg(-1) soil [13-80] for A. caliginosa after 28 days. E. crypticus was not affected by concentrations up to 120 mg LAS kg(-1) soil. When adding (low contaminated) non-spiked sludge to soil, high stimulation of reproduction was observed for E. crypticus and A. caliginosa but not for F. candida. We argue that this difference in stimulative response between the tested species is related to the difference in feeding behaviour. Sludge spiked with LAS did not significantly affect the reproduction of F. candida (fertility: number of juvenile offspring) and A. caliginosa (fecundity: number of cocoons) (dose equivalent to 181 g and 91 g LAS kg(-1) sludge, respectively). Significantly reduced reproduction was observed for E. crypticus (at 120 mg LAS kg(-1) soil+sludge corresponding to 72 g LAS kg(-1) sludge) compared to non-spiked sludge. The reproduction by E. crypticus was, however, comparable to the reproduction observed in the control soil without sludge. Compared to LAS directly spiked to soil, the reproductive output of organisms exposed to spiked sludge was either not significantly different (F. candida, E. crypticus) or significantly improved (A. caliginosa). More studies are needed in order to make firm conclusions on the potential effect of artificially contaminated sludge in soil systems.     

Combined effect of copper and prolonged summer drought on soil microarthropods in the field

Soil microarthropods experience a large range of natural stressors in their natural environment, e.g. variations in temperature and soil moisture, but also anthropogenic stressors such as soil pollutants. In the present study the combined effect of drought stress and copper pollution on microarthropods was investigated in a field study. We hypothesised that microarthropods in copper polluted soil would be more susceptible to drought than animals in control soil. Surprisingly, the abundance of microarthropods in autumn was positively affected by summer drought and copper pollution did not influence the effect of drought in a negative way. The stimulation was mainly seen as an increase of Acari, but also groups of Collembola were positively affected. We suggest that the positive effect of the enforced summer drought could be due to a rapid recovery, which further is accelerated by an increase of food resources (microbes) which have not been utilized during the drought.     

Plasma concentration of organochlorine compounds is associated with age and not obesity

It has been suggested that obese individuals, because of an increased dilution space (body fat) for lipophilic organochlorines compounds, may have greater levels of toxic pollutants than lean sedentary individuals. It is important to further examine this possibility because of the potential contribution of organochlorine pesticides in the development of Parkinson's disease and other neurological diseases. The aim of this study was to further investigate the relationship between the magnitude of obesity and the plasma concentration of organochlorines for a wide range of BMI (with participants at steady state body weight). Fifty-three individuals were selected on the basis of their body mass index (BMI): lean controls (n=16; mean BMI 22.8+/-2.2 kg/m(2); mean age 38.8+/-9.4 years), obese individuals (n=19; mean BMI 33.4+/-3.0 kg/m(2); mean age 38.6+/-7.6 years) and morbidly obese individuals (n=18; mean BMI 49.3+/-6.5 kg/m(2); mean age 44.3+/-9.2 years). Blood samples were analyzed for organochlorine compounds. The relationship between the total plasma organochlorine concentration and BMI was tested using a multiple regression analysis. Age was included in the model. There was no relationship between the total plasma organochlorine concentration and BMI. Organochlorine concentrations, however, were correlated with age (BMI-adjusted R(2)=0.46; p<0.001). At steady state body weight, toxic pollutant concentrations are not associated to obesity but strongly correlate with age.     

Investigating the chemical nature of humic-like substances (HULIS) in North American atmospheric aerosols by liquid chromatography tandem mass spectrometry

The high-molecular weight water-soluble organic compounds present in atmospheric aerosols underwent functional-group characterization using liquid chromatography tandem mass spectrometry (LC-MS/MS), with a focus on understanding the chemical structure and origins of humic-like substances (HULIS) in the atmosphere. Aerosol samples were obtained from several locations in North America at times when primary sources contributing to organic aerosol were well-characterized: Riverside, CA, Fresno, CA, urban and peripheral Mexico City, Atlanta, GA, and Bondville, IL. Chemical analysis targeted identification and quantification of functional groups, such as aliphatic, aromatic, and bulk carboxylic acids, organosulfates, and carbohydrate-like substances that comprise species with molecular weights (MW) 200–600 amu. Measured high-MW functional groups were compared to modeled primary sources with the purpose of identifying associations between aerosol sources, high-MW aerosol species, and HULIS. Mobile source emissions were linked to high-molecular weight carboxylic acids, especially aromatic acids, biomass burning was associated with carboxylic acids and carbohydrate-like substances, and secondary organic aerosol (SOA) correlated well with the total amount of HULIS measured, whereas organosulfates showed no correlation with aerosol sources and exhibited unique spatial trends. These results suggested the importance of motor vehicles, biomass burning, and SOA as important sources of precursors to HULIS. Structural characteristics of atmospheric HULIS were compared to terrestrial humic and fulvic acids and revealed striking similarities in chemical structure, with the exception of organosulfates which were unique to atmospheric HULIS.