N-Acetyl cysteine improves cellular growth in respiratory-deficient yeast.

BACKGROUND: Reactive oxygen species (ROS) is a main factor that alters cellular physiology and functionality. Many strategies are used in order to control excessive oxidative stress. One strategy includes the use of antioxidants like N-acetyl cysteine (NAC). The aim of this study was to compare the effect of this antioxidant on ROS production and cellular growth of a wild-type and a respiratory-deficient Saccharomyces cerevisiae strain. METHODS: Using a simple system such as yeast allows oxidative stress investigations on which numerous factors are more manageable or circumscribed than in a higher organism. We grew cells in a complex medium and incubated them during 72 h. Later, cellular viability and ROS production was evaluated. ROS level was estimated by use of fluorescence signal with 2',7'-dichlorofluorescein diacetate (DCFH-DA). RESULTS: As it is found in the present work, a reducing environment exerted by NAC presence during incubation of the cells allows a respiratory-deficient Saccharomyces cerevisiae strain to improve its cellular growth. CONCLUSIONS: It seems likely that the energy production or the phenotype which characterizes a deficient strain is incapable of palliating ROS growth inhibition while NAC helps to overcome this limitation.

Parenteral succinate reduces levels of reactive oxygen species without changing serum caspase-3 levels in septic rats.

INTRODUCTION: Sepsis is a syndrome of physiological, pathological, and biochemical disorders with several processes co-occurring; reactive oxygen species (ROS) production and apoptosis are 2 of them. Succinate is a Krebs cycle intermediate that is oxydized in complex II of the mitochondria. This study aims to investigate the influence of succinate infusion on these processes. MATERIAL AND METHODS: Sepsis was induced with caecal ligation and puncture in 200 gr Sprague Dawley rats. Four groups were formed with 10 animals (1 - control, 2 - succinate, 3 - sepsis, and 4 - sepsis + succinate). 5 mmol kg-1 of intraperitoneal succinate were administered twice in groups 2 and 4. ROS and caspase-3 levels were measured. RESULTS: Overall, ROS levels (P = 0.017), but not caspase-3 levels (P = 0.89) differed significantly between the groups. The succinate administration reduced serum ROS levels (group 4 vs. 3) in a statistically significant way [0.0623 units (95% CI: 0.0547-0.0699) vs. 0.0835 (0.06-0.106), P = 0.017)], but it did not reduce serum caspase-3 levels (P = 0.39). There was no correlation between serum ROS levels and serum caspase-3 levels. CONCLUSIONS: In this model, ROS levels were reduced with succinate infusion, but caspase-3 levels were not. In addition, ROS levels and apoptosis levels are not correlated, which suggests that those processes occur at different times.

Biochemical study of idebenone effect on mitochondrial metabolism of yeast.

The aim of this work was to study the effect of the drug idebenone on the growth of a strain of Saccharomyces cerevisiae yeast and its respiratory-deficient mutant (rho(0)). We took this yeast as a model system of the interaction of the drug with mammalian cells. The effect of idebenone was evaluated in rich and minimal media. In the S288c strain, idebenone exerted a growth inhibitory effect in concentrations higher than 50 microM in media containing a carbon source consumed at mitochondrial level. In conditions of low oxygen supply, idebenone allows yeast to keep a cellular yielding comparable with conditions of normal oxygen supply. Also, the presence of idebenone in the growth media increased by 50% the fluorescence signal of rhodamine 123, indicating a higher mitochondrial membrane potential. The results could explain the effect of idebenone in the treatment of diseases in which oxygen deficiency alters the energetic metabolism of the cell.

Teaching lactose metabolism: A Complex Challenge Faced with a Simple Kit.

We developed an experimental didactic proposal to teach both carbohydrate metabolism and lactose intolerance as the disease related to that metabolism. Therefore, we implemented an empirical strategy consisting of inexpensive and nontoxic components for which students do not need to know any of the laboratory techniques. The fact that students were able to discuss their own results obtained from the experiments performed in their classroom gave them an additional motivation to learn the subject.

Brefeldin A decreases the activity of the general amino acid permease (GAP1) and the more specific systems for L-leucine uptake in Saccharomyces cerevisiae.

Brefeldin A is a commonly used antifungal agent that reversibly blocks protein transport from the endoplasmic reticulum to the Golgi complex. In this study, we aimed to characterize L-leucine uptake in Saccharomyces cerevisiae in the presence of brefeldin A. For this purpose, we used a synthetic medium, containing L-proline and the detergent SDS, which allows the agent to permeate into the yeast cell. The results obtained with a wild type strain and a gap1 mutant indicate that BFA causes either direct or indirect modification of the transport and/or processing of L-leucine permeases. The presence of BFA affects the kinetic parameter values for L-leucine uptake and decreases not only the uptake mediated by the general system (GAP1), but also that through the specific BAP2 (S1) and/or S2 systems.

A Simple Chemical Method for Rendering Wild-Type Yeast Permeable to Brefeldin A That Does Not Require the Presence of an erg6 Mutation.

The present work aims to develop a growth medium to render a wild-type strain of Saccharomyces cerevisiae permeable to the antifungal drug Brefeldin A. In the current study, a synthetic medium containing 0.1% L-proline and supplemented with $3.0\times 10;{-3}$ % SDS is employed. When Brefeldin A is added to this medium, a wild-type strain shows increased growth sensitivity and a diminished transport of the amino acid L-leucine. Since Brefeldin A exerts its effect on the endoplasmic reticulum and the Golgi apparatus, the medium permits the study of the drug effect on the intracellular traffic of L-leucine permeases.