Effects of selenium on oxidative damage and antioxidant enzymes of eukaryotic cells: wine Saccharomyces cerevisiae.

AIM: To clarify the effects of selenium (Se), parameters related to oxidative issues, as well as the antioxidant response were investigated on an autochthonous wine yeast strain. METHODS AND RESULTS: Antioxidant enzyme activity, gel electrophoresis, Western blot and MDA level were used to investigate the effects of different concentration of Se in wine yeast. We found that Se is able to affect the enzymatic activities of catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD). An increase in lipid peroxidation was observed in a dose-dependent manner of (Se), thus, indicating the occurrence of cell membrane damage. Additionally, Se induced post-translational oxidative modifications of proteins, especially oxidation of thiol groups (both reversible and irreversible) and protein carbonylation (irreversible oxidation). CONCLUSION: These results obtained could further the understanding the effect of different concentration of Se in wine yeast strain with which Se affect the enzymatic activities and induces some post-translational modifications of proteins. SIGNIFICANCE AND IMPACT OF THE STUDY: The understanding of mechanisms regulating the response of wine yeast to Se is important for future work using selenized yeast as enriched Se supplements in human nutrition.

Spatial and temporal genetic variation in Tunisian field populations of Macrosiphum euphorbiae (Thomas).

The potato aphid Macrosiphum euphorbiae (Thomas) is a major pest of several economic crops in Tunisia. Using 10 microsatellites, we analyzed five populations of M. euphorbiae sampled during the 2004-2005 solanaceous and cucurbit season (April through September) from five geographic origins. From 235 aphids, 61 different multilocus genotypes were identified of which three genotypes MLG1, MLG2, and MLG42 were predominant on all host plants and regions. MLG1 and MLG2 genotypes were detected in 2004 and did not reappear in spring 2005, while the genotype MLG42 was detected only in 2005. All populations showed significant deviation from Hardy-Weinberg equilibrium even in data sets including one individual per genotype. χ(2) independence tests and analysis of molecular variance showed no significant differentiation among populations collected on different host plant and from different geographic origin, but differences between populations from two successive years were significant. Factorial component analysis corroborates these results. The probable causes of this seasonal variation were discussed.