Authors:Gábor Máté, Dominika Kovács, Zoltán Gazdag, Miklós Pesti and Árpád Szántó
The present study investigated the linalool (Lol)-induced effects in acute toxicity tests in the human pathogen Candida albicans (C. albicans). Lol treatments induced reduced germ tube formation of the pathogen, which plays a crucial role in the virulence. In comparison with the untreated control, the exposure of 107 cells ml−1 to 0.7 mM or 1.4 mM Lol for one hour induced 20% and 30% decrements, respectively, in the colony-forming ability. At the same time, these treatments caused dose-dependent decrease in the levels of superoxide anion radical and total reactive oxygen species, while there was 1.5 and 1.8-fold increases in the concentrations of peroxides and lipid peroxides, respectively, indicating oxidative stress induction in the presence of Lol. Lol treatments resulted in different adaptive modifications of the antioxidant system. In 0.7 mM-treated cells, decreased specific activities of superoxide dismutase and catalase were detected, while exposure to 1.4 mM Lol resulted in the up-regulation of catalase, glutathione reductase and glutathione peroxidases.
Authors:Zoltán Gazdag, Timea Stromájer-Rácz, Joseph Belagyi, Richard Y. Zhao, Robert T. Elder, Eszter Virág and Miklós Pesti
The wild-type viral protein R (Vpr) of human immunodeficiency virus type 1 exerts multiple effects on cellular activities during infection, including the induction of cell cycle G2 arrest and the death of human cells and cells of the fission yeast Schizosaccharomyces pombe. In this study, wild-type Vpr (NL4-3Vpr) integrated as a single copy gene in S. pombe chromosome was used to investigate the molecular impact of Vpr on cellular oxidative stress. NL4-3Vpr triggered an atypical response in early (14-h), and a wellregulated oxidative stress response in late (35-h) log-phase cultures. Specifically, NL4-3Vpr expression induced oxidative stress in the 14-h cultures leading, to decreased levels of superoxide anion (O2·−), hydroxyl radical (·OH) and glutathione (GSH), and significantly decreased activities of catalase, glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase and glutathione S-transferase. In the 35-h cultures, elevated levels of O2·− and peroxides were accompanied by increased activities of most antioxidant enzymes, suggesting that the Vpr-induced unbalanced redox state of the cells might contribute to the adverse effects in HIV-infected patients.