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3,4-Methylenedioxymethamphetamine (MDMA, “ecstasy”) is an amphetamine-related drug that may damage the dopaminergic nigrostriatal system. To investigate the mechanisms that sustain this toxic effect and ascertain their sex-dependence, we evaluated in the nigrostriatal system of MDMA-treated (4 × 20 mg/kg, 2 h apart) male and female mice the activity of superoxide dismutase (SOD), the gene expression of SOD type 1 and 2, together with SOD1/2 co-localization with tyrosine hydroxylase (TH)-positive neurons. In the same mice and brain areas, activity of glutathione peroxidase (GPx) and of β2/β5 subunits of the ubiquitin-proteasome system (UPS) were also evaluated. After MDMA, SOD1 increased in striatal TH-positive terminals, but not nigral neurons, of males and females, while SOD2 increased in striatal TH-positive terminals and nigral neurons of males only. Moreover, after MDMA, SOD1 gene expression increased in the midbrain of males and females, whereas SOD2 increased only in males. Finally, MDMA increased the SOD activity in the midbrain of females, without affecting GPx activity, decreased the β2/β5 activities in the striatum of males and the β2 activity in the midbrain of females. These results suggest that the mechanisms of MDMA-induced neurotoxic effects are sex-dependent and dopaminergic neurons of males could be more sensitive to SOD2- and UPS-mediated toxic effects.

In this paper, a hypothesis was assessed whether or not the intoxication with copper and supplementation with copper plus resveratrol would result in changes in the activities of catalase and glutathione peroxidase and moreover if the characteristic changes would appear in concentrations of copper, iron, calcium, magnesium, and zinc in the serum of rats with chemically induced carcinogenesis. Female Sprague-Dawley rats were divided into study groups which, apart from the standard diet, were treated with copper (42.6 mg Cu/kg food as CuSO₄·5H₂O) or copper plus resveratrol (0.2 mg/kg body) via gavage for a period from 40 days until 20 weeks of age. In cancer groups, the rats were treated with a dose of 80 mg/body weight of 7,12-dimethyl-1,2-benz[a]anthracene (DMBA) given in rapeseed oil at 50 and 80 days of age to induce mammary carcinogenesis. The control groups included the rats kept in the same conditions and fed with the same diet as the animals from the study groups, but not DMBA-treated. The activity of catalase significantly decreased in groups of rats with mammary carcinogenesis that were supplemented with copper (p < 0.05) or copper plus resveratrol (p < 0.001) in comparison with the control groups that received the same diets. In cancer groups of nonsupplemented rats, the increase of glutathione peroxidase activity was observed. The process of carcinogenesis and the applied supplementation significantly altered the concentrations of trace elements in serum, in particular as concerns iron and copper. The mean serum iron levels in rats with breast cancer were significantly lower than those in the control groups (p < 0.001). The mean serum copper levels significantly decreased in the groups of rats with mammary carcinogenesis that were supplemented with copper or copper plus resveratrol in comparison with the control groups that received the same diets (p < 0.001). The characteristic changes in iron content and the zinc/copper and zinc/iron ratios in blood may be used as one of the prognostic factors in breast cancer research.

During the peripartum period, high-yielding dairy cows experience metabolic stress, which alters their homeostasis and exposes the cows to illness. The aim of this study was to quantify the expression levels of genes involved in antioxidant defences during the transition period in the blood of dairy cows and to evaluate the regulative activity on these genes of natural antioxidants in the diet. Three groups of 7 heifers each, at the 7th month of pregnancy, were used. Starting from 3 weeks before the expected calving date (-22 days), the three groups were allotted to the following experimental treatments: control (CTR, basal diet); lycopene (LYC, basal diet + lycopene 540 mg/day) and grape polyphenols (POL, basal diet + grape polyphenols 10 g/day). Blood was sampled at 22 and 8 days before and 8, 15 and 22 after calving and analysed for the expression level of glutathione peroxidase (GPx) and superoxide dismutase (Cu/ZnSOD) using the real-time PCR technique with LUX (Light Upon eXtension) fluorogenic primers. During the peripartum period (-22 days until + 22 days from calving), Cu/ ZnSOD mRNA expression decreased (p<0.05) in the CTR and LYC groups, but increased at 15 days after calving in the POL group. No significant differences were found in GPx mRNA expression. The results suggest that grape polyphenols may have a controlling effect on peripartum metabolic stress through modulation of superoxide dismutase expression.

Under in vitro conditions, we examined the effects of silver nanoparticles (AgNPs) and silver (Ag) ions on potato (Solanum tuberosum L.) in terms of silver accumulation, production of reactive oxygen species (ROS), oxidative stress responses, and antioxidative defense systems. At all concentrations (except at 2 mg•L-1), the amount of Ag in the shoots and roots of Ag ion-treated plantlets was significantly higher than in plantlets treated with AgNPs. In both treatments, total ROS and superoxide anions were increased at concentrations greater than 2 mg•L-1. Damage caused by oxidative stress, such as ion leakage and cell death, was significantly higher in plantlets treated with AgNPs than those treated with Ag ions. Significant increases in the activities of superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase (GR),were found in both AgNP-treated, and Ag ion-treated plantlets compared to the control. However, in AgNP-treated plantlets, GR activity was significantly decreased at 20 mg•L-1. A significant reduction in glutathione (GSH), ascorbate (ASA), and the ratios of GSH to oxidized glutathione (GSSG) and ASA to oxidized ascorbate (DHA)were observed in plantlets treated with both AgNPs and Ag ions at concentrations higher than 2 mg•L-1. Moreover, a greater decrease in GSH and ASA contents was seen in plantlets treated with AgNPs compared to those treated with Ag ions. The present study indicates that both AgNPs and Ag ion treatments impose oxidative stress on potato plantlets under in vitro conditions. Furthermore, based on plantlets’ responses to oxidative damage, the observed alteration in the activities of radical scavenging enzymes and the depletion of GSH and ASA, AgNPs seem to have higher toxicity than the equivalent mass of Ag ions.

Tissue-specific or regulated expression of transgenes is desirable in order to prevent pleiotropic side effects of putatively harmful transgene products as well as loss of energy resources due to unnecessary accumulation of transgene products. Epidermis-specific expression would be useful for many defense-related genes directed against attack by fungal pathogens that enter the plant body by direct penetration through the epidermis. In an approach to enhance resistance of wheat to the powdery mildew fungus Blumeria graminis f.sp. tritici, a novel epidermis-specific promoter was developed and used for expression of two defense-related genes. A 2.3 kb fragment of the wheat GstA1 promoter in combination with an intron-containing part of the wheat WIR1a gene was found to drive strong and constitutive transient expression in wheat epidermis. This promoter-intron combination was used for overexpression of oxalate oxidase9f-2.8 and TaPERO peroxidase, two defense-related wheat genes expressed in inner leaf tissues. Expression studies of several transgenic lines by in situ oxalate-oxidase staining, RNA and protein blot analyses, as well as real-time PCR, demonstrated strong and constitutive transgene expression in the shoot epidermis. Transient as well as stable over-expression of the TaPERO peroxidase gene in wheat epidermis under the control of the GstA1i promoter resulted in enhanced resistance against Blumeria graminis f.sp. tritici, whereas oxalate-oxidase overexpression had no effect in either system. The data suggest that the wheat GstA1 promoter in combination with the WIR1a intron is useful for transgenic approaches to fungal disease resistance in cereals.

Two seed lots of Acer saccharinum (recalcitrant), with an initial moisture content of 50% and 55%, were stored at +3oC for 6 months. After this time, their viability (measured as germinability) reached 100% and 30%, respectively. In embryo axes and cotyledons extracted from seeds, two major low molecular antioxidants were assayed: ascorbate (ASA and DHA) and glutathione (GSH and GSSG); and activities of enzymes of the ascorbate-glutathione cycle were measured: ascorbate peroxidase (APO) (E.C. 1.11.1.11), monodehydroascorbate reductase (MR) (E.C. 1.6.5.4), dehydroascorbate reductase (DHAR) (E.C. 1.8.5.1), and glutathione reductase (GR) (E.C. 1.6.4.2.). GSH and GSSG contents of embryo axes of stored seeds decreased, as compared to the control (fresh, non-stored seeds), but a larger decrease was observed in seeds with 30% viability. In cotyledons, a particularly high increase in the GSH content in relation to the control was observed in seeds with 100% viability, while the GSSG content was significantly lower in both stored seed lots than in the control. The ASA level was twice as high in seeds with 30% viability as in the control, both in embryo axes and in cotyledons. The activity of enzymes of the ascorbate-glutathione cycle was higher in embryo axes than in cotyledons. In embryo axes of seeds with 100% viability, enzyme activities were slightly lower than in the control, while in those of seeds with 30% viability, their activities were higher than in the control. The observed changes in activities of enzymes of the ascorbate-glutathione cycle and in ascorbate and glutathione levels suggest that the stored seeds of A. saccharinum have an active antioxidant system, which plays an important role in maintaining their viability during storage.

During long-term exposure of pine (Pinus sylvestris L.) seedlings to trichloro- and monochloroacetic acids via root uptake or acid mist treatments, both substances were removed from the plant tissues by metabolic activity. None of the treated plants exhibited visible stress symptoms at the concentrations used. In addition, the exposure to both substances led to dramatic changes in the activity of xenobiotic detoxification enzymes (peroxidase and gluthatione S-transferase) in the needles of the plants.