RESUMO
To further elucidate the impact of fermentative stress on Saccharomyces cerevisiae wine strains, we have here evaluated markers of oxidative stress, oxidative damage and antioxidant response in four oenological strains of S. cerevisiae, relating these to membrane integrity, ethanol production and cell viability during fermentation in high-sugar-containing medium. The cells were sampled at different fermentation stages and analysed by flow cytometry to evaluate membrane integrity and accumulation of reactive oxygen species (ROS). At the same time, catalase and superoxide dismutase activities, trehalose accumulation, and protein carbonylation and degradation were measured. The results indicate that the stress conditions occurring during hypoxic fermentation in high-sugar-containing medium result in the production of ROS and trigger an antioxidant response. This involves superoxide dismutase and trehalose for the protection of cell structures from oxidative damage, and protein catabolism for the removal of damaged proteins. Cell viability, membrane integrity and ethanol production depend on the extent of oxidative damage to cellular components. This is, in turn, related to the 'fitness' of each strain, which depends on the contribution of individual cells to ROS accumulation and scavenging. These findings highlight that the differences in individual cell resistances to ROS contribute to the persistence of wine strains during growth under unfavourable culture conditions, and they provide further insights into our understanding of yeast behaviour during industrial fermentation.
Assuntos
Fermentação/fisiologia , Glucose/farmacologia , Estresse Oxidativo/fisiologia , Espécies Reativas de Oxigênio/metabolismo , Saccharomyces cerevisiae/crescimento & desenvolvimento , Antioxidantes/metabolismo , Catalase/metabolismo , Membrana Celular/metabolismo , Meios de Cultura , Etanol/metabolismo , Saccharomyces cerevisiae/metabolismo , Especificidade da Espécie , Superóxido Dismutase/metabolismo , Trealose/metabolismo , Vinho/microbiologiaAssuntos
Proteínas de Bactérias , Membrana Celular/metabolismo , Magnésio/metabolismo , Neurônios/metabolismo , Animais , Antiporters/metabolismo , Humanos , Ativação do Canal Iônico/fisiologia , Canais Iônicos/metabolismo , Transporte de Íons/fisiologia , Células Musculares/metabolismo , Células Procarióticas/metabolismoRESUMO
Gamma-aminobutyric acid (GABA)-related molecules were identified in Paramecium primaurelia by immunocytochemical methods, and GABA(A) receptors by their histochemical BODIPY-binding sites. Confocal microscope analysis showed different localizations according to the stages of the developmental cycle. A comparison was made with the cholinergic molecules, such as the acetylcholine biosynthetic enzyme (choline acetyltransferase), in double-labelled cells by confocal microscopy. In vivo experiments suggested the involvement of GABA-related molecules in cell-cell interaction.