Zinc-induced oxidative stress in Verbascum thapsus is caused by an accumulation of reactive oxygen species and quinhydrone in the cell wall

Oxidative stress is one aspect of metal toxicity. Zinc, although unable to perform univalent oxido-reduction reactions, can induce the oxidative damage of cellular components and alter antioxidative systems. Verbascum thapsus L. plants that were grown hydroponically were exposed to 1 and 5 mM Zn2+. Reactive oxygen species (ROS) accumulation was demonstrated by the fluorescent probe H(2)DCFDA and EPR measurements. The extent of zinc-induced oxidative damage was assessed by measuring the level of protein carbonylation. Activities and isoform profiles of some antioxidant enzymes and the changes in ascorbate and total phenolic contents of leaves and roots were determined. Stunted growth because of zinc accumulation, preferentially in the roots, was accompanied by H2O2 production in the leaf and root apoplasts. Increased EPR signals of the endogenous oxidant quinhydrone, center dot CH3 and center dot OH, were found in the cell walls of zinc-treated plants. The activities of the antioxidative enzymes ascorbate peroxidase (APX) (EC 1.11.1.11), soluble superoxide dismutase (SOD) (EC 1.15.1.1), peroxidase (POD), (EC 1.11.1.7) and monodehydroascorbate reductase (EC 1.6.5.4) were increased; those of glutathione reductase (EC 1.6.4.2), dehydroascorbate reductase (EC 1.8.5.1) and ascorbate oxidase (AAO) (EC 1.10.3.3) were decreased with zinc treatment. Zinc induced a cell-wall-bound SOD isoform in both organs. Leaves accumulated more ascorbate and phenolics in comparison to roots. We propose a mechanism for zinc-promoted oxidative stress in V. thapsus L. through the generation of charge transfer complexes and quinhydrone because of phenoxyl radical stabilisation by Zn2+ in the cell wall. Our results suggest that the SOD and APX responses are mediated by ROS accumulation in the apoplast. The importance of the POD/Phe/AA (ascorbic acid) scavenging system in the apoplast is also discussed

Determination of differential heavy metal and trace element accumulation in liver, gills, intestine and muscle of sterlet (Acipenser ruthenus) from the Danube River in Serbia by ICP-OES

The accumulation of heavy metals in fish has been extensively studied and well documented. However, the research has been mainly focused on the muscle tissue, while the distribution patterns among other tissues, such as liver and gills, have been mostly neglected. Within the present study, the concentrations of Ag, Al, As, B, Ba, Cd, Co, Cr, Cu, Fe. Mn, Mo, Ni, Pb, Se, Sr, Zn and Li in the muscle, gills, liver and intestine of the sterlet (Acipenser ruthenus) from the Danube River have been assessed by using the inductively-coupled plasma optical spectrometry. The analysis has revealed a high degree of differential accumulation of the studied heavy metals and trace elements in the tissues of the Danube sterlet. Liver appeared to be the main heavy metal storage tissue, while the lowest levels of analyzed metals were found in muscles. Heavy metal concentrations in the muscle were at acceptable levels for human consumption, except partly for cadmium. We conclude that, in order to enable a more efficient control of contaminants in fish products, there is an apparent need to resolve the problem of lack of legal limits for many metals in European legislation

Heavy metal and trace element accumulation in muscle, liver and gills of the Pontic shad (Alosa immaculata Bennet 1835) from the Danube River (Serbia)

Pontic shad (Alosa immaculata Bennet 1835) is an anadromous species that lives in the heavily polluted north-western part of the Black Sea and migrates into the Danube River to spawn To assess their heavy metal contamination levels, samples of Politic shad were collected at 863 river kilometre of the Danube River Muscle, liver and gill samples were prepared using microwave digestion. and the analysis of Al, As, Cd, Cu, B. Ba. Fe, Mg. Sr. Zn. Li, Co, Cr. Mn. Mo, Ni and Pb was performed with inductively-coupled plasma-optic emission spectroscopy (ICP-OES). Significant differences in concentrations of analyzed elements were observed among different tissues, as well as between the genders Al, Sr, Ba. Mg, and Li had the highest concentrations in gills, while Cd. Cu, Zn. Fe and B were highest in the liver While the muscle had the lowest concentrations of most of the analyzed elements, it had the highest concentration of As. This study has revealed that the concentrations of Cd and As in Politic shad muscle tissue were above the maximum acceptable concentrations for human consumption, thus precautions need to be taken in order to prevent future heavy metal contaminatio

Heavy metal and trace element accumulation in muscle, liver and gills of the Pontic shad (Alosa immaculata Bennet 1835) from the Danube River (Serbia)

Pontic shad (Alosa immaculata Bennet 1835) is an anadromous species that lives in the heavily polluted north-western part of the Black Sea and migrates into the Danube River to spawn To assess their heavy metal contamination levels, samples of Politic shad were collected at 863 river kilometre of the Danube River Muscle, liver and gill samples were prepared using microwave digestion. and the analysis of Al, As, Cd, Cu, B. Ba. Fe, Mg. Sr. Zn. Li, Co, Cr. Mn. Mo, Ni and Pb was performed with inductively-coupled plasma-optic emission spectroscopy (ICP-OES). Significant differences in concentrations of analyzed elements were observed among different tissues, as well as between the genders Al, Sr, Ba. Mg, and Li had the highest concentrations in gills, while Cd. Cu, Zn. Fe and B were highest in the liver While the muscle had the lowest concentrations of most of the analyzed elements, it had the highest concentration of As. This study has revealed that the concentrations of Cd and As in Politic shad muscle tissue were above the maximum acceptable concentrations for human consumption, thus precautions need to be taken in order to prevent future heavy metal contamination (C) 2010 Elsevier B V All rights reservedMinistry of Science of Republic Serbia [143045

Degradation of linuron in soil by two fungal strains

Two fungal strains were applied to soil polluted with herbicide in order to determine their degradation potential. Three experimental setups were used. In the first setup, the soil in pots was contaminated by linuron in final concentration of 1 ppm. Suspensions of Phanerocheate chrysosporium and Trichoderma asperellum were applied sepa­rately or in combination. Tomato plantlets were transplanted and chlorophyll content in their leaves was determined at two time points during plant growth. In the second setup in pots, the final concentration of linuron was lower, 0.45 ppm. In the third setup 0.1 ppm of linuron was applied in the field plot. Plantlets of lettuce were transplanted and chlorophyll content was measured as indicator of plant stress. The content of linuron in soil was determined by HPLC. The applied fungal strains significantly reduced toxic effect of 0.45 ppm linuron on plants, which was not the case for 1 ppm linuron. Both fungi, applied separately or in combination, were effective in decreasing the linuron content in the soil. However, in field conditions the combination of both fungi was the most effective. [Projekat Ministarstva nauke Republike Srbije, br. III43010

Isolation and characterization of bacteria and yeasts from contaminated soil

Plant growth promoting (PGP) bacteria and yeasts play an important role in bioremediation processes. Thirty bacterial and ten yeast isolates were obtained from PAH and PCB contaminated soil with an aim of determining the presence of PGP mechanisms (production of ammonia, indoleacetic acid, siderophores and solubilization of inorganic phosphate). As a result, three bacterial (Serratia liquefaciens, Micrococcus sp. and Serratia sp.) and two yeast isolates (Candida utilis and Candida tropicalis) were recognized as PGP strains. Among them, Serratia sp. showed the highest indole production (25.5 μg/ml). Analyses of metal tolerance (Cu+2, Cr+6 and Ni+2) revealed that Serratia liquefaciens, Micrococcus sp., Serratia sp. and Candida tropicalis were capable to tolerate significant concentration of metals. As a result of this study several bacterial and yeast strains were attributed as potential plant growth promoters which can be applied in future remediation activities and environmental quality improvements. [Projekat ministarstva nauke Republike Srbije, br. TR 31080 i FP-7 project AREA (316004)