Estudo comparativo dos efeitos tóxicos induzidos por metil e etilmercúrio em Saccharomyces cerevisiae

Abstract

Mercury is a highly toxic metal found in environment mostly due to anthropological and industrial processes. Methylmercury (MeHg) originates from the methylation of inorganic mercury in aquatic environment and accumulates in fish through the food chain. Consumption of contaminated fish is a major form of MeHg poisoning. Ethylmercury (EtHg), which comprises thimerosal is used as a preservative for drugs and vaccines. Studies on the toxicology of EtHg in biological systems are scarce when compared to MeHg. The yeast Saccharomyces cerevisiae has been widely used in toxicological research as an alternative model to study the molecular mechanisms involved in the toxic agents effects, including heavy metals. This study aimed to investigate and compare the toxic effects mediated by MeHg and EtHg in wild type strains and mutants to genes related to oxidative stress in S. cerevisiae.: γ-glutamylcysteine synthetase (ΔGsh1), glutathione peroxidase (ΔGpx1), catalase T (ΔCtt1), superoxide dismutase (ΔSod1), mitochondrial peroxiredoxin (ΔPrx1), cytoplasmic thioredoxin (ΔTrx1) and redox transcription factor (ΔYap1). We evaluate the inhibition of cell growth, as well as the mutant strains tolerance to the compounds. Furthermore, we evaluated the oxidation of DHR123 and membrane permeability by flow cytometry. Our data showed an increase in the formation of ROS and membrane permeability in wild type strains exposed to MeHg and EtHg. Furthermore, there was an inhibition of cell growth in wild type and mutant strains after treatment with the compounds. In general, the data obteined contribute to the understanding of the toxicology of mercury compounds using an alternative model, which has great advantages in terms of cost, maintenance, reproducibility and experimental time.