Comparative Analysis of the Gut Microbiota of Bat Species with Different Feeding Habits.

Bats are a diverse and ecologically important group of mammals that exhibit remarkable diversity in their feeding habits. These diverse feeding habits are thought to be reflected in the composition and function of their gut microbiota, which plays important roles in nutrient acquisition, immune function, and overall health. Despite the rich biodiversity of bat species in South America, there is a lack of microbiome studies focusing on bats from this region. Such studies could offer major insights into conservation efforts and the preservation of biodiversity in South America. In this work, we aimed to compare the gut microbiota of four bat species with different feeding habits from Southern Brazil, including nectarivorous, frugivorous, insectivorous, and hematophagous bats. Our findings demonstrate that feeding habits can have a significant impact on the diversity and composition of bat gut microbiotas, with each species exhibiting unique metabolic potentials related to their dietary niches. In addition, the identification of potentially pathogenic bacteria suggests that the carriage of microbial pathogens by bats may vary, depending on feeding habits and host-specific factors. These findings provide novel insights into the relationship between bat feeding habits and gut microbiota composition, highlighting the need to promote diverse habitats and food sources to support these ecologically important species.

Distribution and Utilization of Vitamin E in Different Organs of Wild Bats from Different Food Groups.

In this work, we examined the levels of vitamin E in the heart, liver, and kidneys of four species of adult male bats with distinct feeding habits. Our results indicate consistent vitamin E levels in the heart across all four bat species, suggesting the presence of regulatory mechanisms. Additionally, the liver displayed notably higher vitamin E levels in nectarivorous and frugivorous bats, while hematophagous bats exhibited lower levels, indicating a link between dietary intake and liver vitamin E levels. Furthermore, correlation analysis provided additional insights into the relationships between vitamin E and key antioxidant parameters in the livers of bats. On the other hand, no correlation was observed between vitamin E and key antioxidant parameters in the heart. Intriguingly, vitamin E was not detected in the kidneys, likely due to physiological factors and the prioritization of vitamin E mobilization in the heart, where it serves critical physiological functions. This unexpected absence of vitamin E in bat kidneys highlights the unique metabolic demands and prioritization of vitamin mobilization in wild animals like bats, compared to conventional animal models. These findings provide insight into the intricate distribution and utilization of vitamin E in bats, emphasizing the influence of dietary intake and metabolic adaptations on vitamin E levels in different organs.

Oxidative Stress and Antioxidant Defense in the Heart, Liver, and Kidney of Bat Species with Different Feeding Habits.

The aim of this study was to compare the oxidative metabolism of four neotropical bat species with different feeding habits and investigate the relationship between their feeding habits and oxidative status. In terms of oxidative damage, our findings revealed major differences among the four bat species. In particular, hematophagous bats had lower levels of oxidative damage in the heart but higher levels in the liver. Nectarivorous bats had lower levels of carbonyl groups in the kidneys compared to insectivorous and hematophagous bats. The activity of various antioxidant and non-antioxidant enzymes in the heart, liver, and kidney also showed significant differences among the bat species. H2O2 consumption was lower in the heart of hematophagous bats, while insectivorous bats exhibited the highest enzymatic activity in the kidney. SOD activity was lower in the heart of hematophagous bats and lower in nectarivorous bats in the liver. Fumarase activity was higher in the heart of frugivorous/insectivorous and lower in nectarivorous/hematophagous bats. GPx activity was higher in the heart of nectarivorous/insectivorous and higher in the kidney of insectivorous bats. GST activity was higher in the heart of nectarivorous and lower in hematophagous bats. The correlation analysis between oxidative markers and enzymatic/non-enzymatic antioxidants in the heart, liver, and kidney exhibited distinct patterns of correlations due to variations in antioxidant defense mechanisms and oxidative stress responses in different organs. The observed differences in oxidative damage, antioxidant enzyme activities, and correlations between oxidative markers and antioxidants highlight the adaptability and complexity of the antioxidant defense systems in these bats. Each organ appears to have specific demands and adaptations to cope with oxidative stress based on its physiological functions and exposure to dietary components. Our results have major significance for the conservation and management of bats, which are threatened species despite being crucial components of ecosystems. Our study's implications go beyond bat biology and offer valuable insights into comparative oxidative physiology.

Oxidative Stress and Antioxidant Defense in the Brain of Bat Species with Different Feeding Habits.

Assessing the levels of oxidative stress markers and antioxidant enzymes in the brain is crucial in evaluating its antioxidant capacity and understanding the influence of various dietary patterns on brain well-being. This study aimed to investigate the antioxidant status and oxidative damage in the brain of bat species with different feeding habits to gain insights into their protective mechanisms against oxidative stress and their interspecific variation. The levels of oxidative damage markers and the activities of antioxidants were measured in the brain of four bat species with different feeding habits, namely insectivorous, frugivorous, nectarivorous, and hematophagous. Insectivorous bats showed higher levels of SOD and fumarase compared to the other groups, while hematophagous bats showed lower levels of these enzymes. On the other hand, the activities of glutathione peroxidase and glutathione S-transferase were higher in hematophagous bats and lower in insectivorous bats. The carbonyl groups and malondialdehyde levels were lower in frugivores, while they were similar in the other feeding guilds. Nitrite and nitrate levels were higher in the hematophagous group and relatively lower in all other groups. The GSSG/GSH ratio was higher in the hematophagous group and lower in frugivores. Overall, our results indicate that the levels of oxidative stress markers and the activities of antioxidant enzymes in the brain vary significantly among bat species with different feeding habitats. The findings suggest that the antioxidant status of the brain is influenced by diet and feeding habits.

Vitamin C Levels in Different Organs of Bat Species from Different Food Groups.

Unlike most animals, most bats cannot synthesize vitamin C endogenously. Consequently, this vitamin must be obtained from the diet. Among the bat species, there are several food groups, such as frugivorous, nectarivorous, insectivorous, and hematophagous. In this work, we measured and compared vitamin C levels in different organs of four species of bats, all collected in southern Brazil. When analyzing and comparing the levels of vitamin C in the four bat species, (regardless of the organ), no significant differences were observed. However, when analyzing and comparing the levels of vitamin C in the four organs (regardless of the species), significant differences were observed, with the highest concentrations in the heart, followed by the liver and brain, while the lowest concentration was measured in the kidneys. Additional differences in the levels of Vitamin C were only observed when each organ was analyzed according to the species/diet. These results indicate a high degree of metabolic homeostasis in bats despite the marked difference in the type of diet.

Role of asthma and intolerance to acetylsalicylic acid on the redox profile in nasal polyp tissue.

PURPOSE: Nasal polyposis is a chronic inflammatory disease of the mucosa of the nasal cavity and paranasal sinuses. The etiology of nasal polyposis is unclear; however, it may be associated with asthma and intolerance to acetylsalicylic acid, possibly altering the redox profile. The study intends to compare the redox profile in polyps surgically removed from three clinical groups of patients with nasal polyposis who were divided according to the presence of asthma and intolerance to acetylsalicylic acid. METHODS: Patients were divided into three groups: nasal polyposis only (n = 30); nasal polyposis and asthma (n = 19); and nasal polyposis, asthma and intolerance to acetylsalicylic acid (n = 10). The following redox evaluations were performed: enzymatic antioxidant activity of superoxide dismutase, glutathione peroxidase, hydrogen peroxide consumption and glutathione S-transferase; non-enzymatic antioxidant levels of vitamin C, vitamin E and glutathione; levels of the oxidative damage biomarkers carbonyl groups (measuring protein damage) and malondialdehyde (measuring lipid peroxidation); and nitrite and nitrate levels. RESULTS: Compared with the polyposis only group, hydrogen peroxide consumption, glutathione S-transferase, vitamin E and malondialdehyde were lower in the asthma group. Total glutathione (0.12 ± 0.01 vs. 33.34 ± 10.48 µmol/mg) and nitrite and nitrate (0.06 ± 0.01 vs. 15.95 ± 1.38 nmol/mg) levels were higher in the nasal polyposis, asthma and intolerance to acetylsalicylic acid group. CONCLUSIONS: In patients with nasal polyposis, asthma may alter the redox profile associated with the hydrogen peroxide and lipid damage pathways, whereas asthma and intolerance to acetylsalicylic acid increase nitrite and nitrate and total glutathione levels.

Effects of lipoic acid and n-3 long-chain polyunsaturated fatty acid on the liver ovariectomized rat model of menopause.

BACKGROUND: Bilateral ovariectomy is an experimental model used to analyse the effects of menopause and develop strategies to mitigate the deleterious effects of this condition. Supplementation of the diet with antioxidants has been used to reduce potential oxidative stress caused by menopause. The purpose of the study was to analyse the effects of α-lipoic acid (LA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), dietary supplementation on oxidative stress in the livers of ovariectomized rats. METHODS: In this study, we evaluated the effect of dietary supplementation with LA, DHA and EPA for a period of 16 weeks on oestrogen levels and oxidative stress biomarkers in the livers of ovariectomized 25 three-month-old rats. RESULTS: Serum oestrogen levels were lower after ovariectomy but were not altered by dietary treatments. LA was capable of acting in the liver, recovering the activity of the antioxidant enzymes superoxide dismutase and glutathione peroxidase, and reducing protein oxidative damage. Moreover, LA supplementation reduced nitrite and nitrate levels. DHA and EPA recovered the antioxidant activity of cytosolic and mitochondrial superoxide dismutase, decreasing protein oxidation. Protection against lipid oxidation differed between treatments. The DHA-treated group showed increased levels of the lipid peroxidation biomarker malondialdehyde compared to the ovariectomized group. However, malondialdehyde levels were not altered by EPA treatment. CONCLUSIONS: The results suggest that the antioxidant response varies among evaluated supplementations and all supplements were able to alter enzymatic and non-enzymatic antioxidants in the livers of ovariectomized rats. DHA presented the most evident antioxidant effect, decreasing protein and lipid damage.

Sexual activity affects the redox profile along the aging process in male rats.

The disposable soma theory postulates that aging might be the result of tradeoffs between early life reproduction and longevity, thereby involving the costs of reproduction in the expected lifespan. It is known that redox biochemistry plays a major role in these processes. To assess long term effects of reproduction, we analyzed redox rates and the testosterone levels at four different ages, and we performed a principal component analysis between redox measures of five different organs followed by a cluster analysis to determine correlations. The correlations among redox measures between organs were influenced more by reproduction than by age. Non breeders showed no alterations along the aging process up to 24 months, at which point differences were seen. Among breeders, however, we saw differences between three age clusters: cluster 1, 6 month old-animals; cluster 2, 12 month old animals, and cluster 3, 3 and 24 month-old animals. The results show differences between male breeders and non breeders, and provide evidence that oxidative stress plays a role in aging, and that reproduction alters the redox profiles of males.

Redox changes in the brains of reproductive female rats during aging.

Reproduction is a critical and demanding phase of an animal's life. In mammals, females usually invest much more in parental care than males, and lactation is the most energetically demanding period of a female's life. Here, we tested whether oxidative stress is a consequence of reproduction in the brains of female Wistar rats. We evaluated the activities of glutathione peroxidase, glutathione S-transferase, and superoxide dismutase; H2O2 consumption; protein carbonylation; NO2 & NO3 levels; and total glutathione, as well as sex hormone levels in brain tissue of animals at 3, 6, 12, and 24months of age. Animals were grouped according to reproductive experience: breeders or non-breeders. Most of the studied parameters showed a difference between non-breeders and breeders at 12 and 24months. At 24months of age, breeders showed higher superoxide dismutase activity, H2O2 consumption, glutathione peroxidase activity, and carbonyl levels than non-breeders. In 12-month-old non-breeders, we observed a higher level of H2O2 consumption and higher superoxide dismutase and glutathione peroxidase activities than breeders. By evaluating the correlation network, we found that there were a larger number of influential nodes and positive links in breeder animals than in non-breeders, indicating a greater number of redox changes in breeder animals. Here, we also demonstrated that the aging process caused higher oxidative damage and higher antioxidant defenses in the brains of breeder female rats at 24months, suggesting that the reproduction process is costly, at least for the female brain. This study shows that there is a strong potential for a link between the cost of reproduction and oxidative stress.

Oxidative stress in testis of animals during aging with and without reproductive activity.

The free radical theory of aging postulates that an imbalance between reactive oxygen species (ROS) and reactive nitrogen species (RNS) and antioxidant defenses is important in senescence. To address this issue and gain insight into the aging process, we have evaluated the antioxidant defenses and have assessed oxidative damage in testis tissues in aging male rats. In order to relate aging and reproduction, animals with and without reproductive activity were studied. In reproductive animals the results showed a progressive increase in antioxidant enzyme activity until 12 months of age followed by an abrupt fall at 24 months. In non-reproductive animals, antioxidant activity was stable through 12 months of age, but again, fell abruptly at 24 months of age. In addition, increased aconitase activity and increased testosterone levels were found among reproductively active animals. The data demonstrate the existence of metabolic differences in testis of reproductively experienced animals and reproductively naïve animals.

Glutathione levels in and total antioxidant capacity of Candida sp. cells exposed to oxidative stress caused by hydrogen peroxide.

INTRODUCTION: The capacity to overcome the oxidative stress imposed by phagocytes seems to be critical for Candida species to cause invasive candidiasis. METHODS: To better characterize the oxidative stress response (OSR) of 8 clinically relevant Candida sp., glutathione, a vital component of the intracellular redox balance, was measured using the 5,5'-dithiobis-(2-nitrobenzoic acid (DTNB)-glutathione disulfide (GSSG) reductase reconversion method; the total antioxidant capacity (TAC) was measured using a modified method based on the decolorization of the 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic) acid radical cation (ABTS*+). Both methods were used with cellular Candida sp. extracts treated or not with hydrogen peroxide (0.5 mM). RESULTS: Oxidative stress induced by hydrogen peroxide clearly reduced intracellular glutathione levels. This depletion was stronger in Candida albicans and the levels of glutathione in untreated cells were also higher in this species. The TAC demonstrated intra-specific variation. CONCLUSIONS: Glutathione levels did not correlate with the measured TAC values, despite this being the most important non-enzymatic intracellular antioxidant molecule. The results indicate that the isolated measurement of TAC does not give a clear picture of the ability of a given Candida sp. to respond to oxidative stress.

Glutathione levels in and total antioxidant capacity of Candida sp. cells exposed to oxidative stress caused by hydrogen peroxide / Níveis de glutationa e capacidade antioxidante total em células de Candida sp. expostas a estresse oxidativo causado por peróxido de hidrogênio

INTRODUCTION: The capacity to overcome the oxidative stress imposed by phagocytes seems to be critical for Candida species to cause invasive candidiasis. METHODS: To better characterize the oxidative stress response (OSR) of 8 clinically relevant Candida sp., glutathione, a vital component of the intracellular redox balance, was measured using the 5,5'-dithiobis-(2-nitrobenzoic acid (DTNB)-glutathione disulfide (GSSG) reductase reconversion method; the total antioxidant capacity (TAC) was measured using a modified method based on the decolorization of the 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic) acid radical cation (ABTS*+). Both methods were used with cellular Candida sp. extracts treated or not with hydrogen peroxide (0.5 mM). RESULTS: Oxidative stress induced by hydrogen peroxide clearly reduced intracellular glutathione levels. This depletion was stronger in Candida albicans and the levels of glutathione in untreated cells were also higher in this species. The TAC demonstrated intra-specific variation. CONCLUSIONS: Glutathione levels did not correlate with the measured TAC values, despite this being the most important non-enzymatic intracellular antioxidant molecule. The results indicate that the isolated measurement of TAC does not give a clear picture of the ability of a given Candida sp. to respond to oxidative stress.

INTRODUÇÃO: A capacidade de suportar o estresse oxidativo imposto por fagócitos parece ser crítica para que espécies de Candida causem candidíase invasiva. MÉTODOS: Para melhor caracterizar a resposta ao estresse oxidativo (REO) de oito Candida sp. clinicamente relevantes, um componente vital do balanço redox intracelular, a glutationa, foi mensurada pelo método de reconversão DTNB-GSSG redutase e a capacidade antioxidante total (CAT) foi mensurada por um método modificado baseado na descoloração do ABTS*+. Ambos os métodos foram utilizados em extratos celulares das espécies de Candida tratadas ou não com peróxido de hidrogênio (0,5mM). RESULTADOS: O estresse oxidativo induzido pelo peróxido de hidrogênio claramente reduziu os níveis intracelulares de glutationa. Esta diminuição foi mais intensa em C. albicans e os níveis de glutationa em células não tratadas foram também maiores nesta espécie. A capacidade antioxidante total demonstrou variação intraespecífica na capacidade antioxidante. CONCLUSÕES: Os níveis de glutationa não se correlacionaram com a capacidade antioxidante total mensurada, apesar desta ser a defesa antioxidante intracelular não-enzimática mais importante. Os resultados indicam que a medição isolada da CAT não fornece um quadro claro da habilidade de certa espécie de Candida responder ao estresse oxidativo.

Oxidative stress in the brain of reproductive male rats during aging.

Reproduction alters the male physiology. We performed a comprehensive study to examine oxidative stress in the brains of male rats with (experienced) or without (naïve) reproductive activity during aging. Oxidative stress was assessed by measuring the activity of catalase, glutathione peroxidase, superoxide dismutase, glutathione S-transferase, aconitase, and aconitase reactivated, and by measuring lipid peroxidation, protein carbonylation, nitrite and nitrate levels, vitamin C levels, and glutathione (total, reduced, oxidized forms) levels in brain tissue, as well as testosterone and estradiol levels in serum. Reproductively active animals exhibited increased testosterone levels and aconitase activity, suggesting an increased metabolism. Increased antioxidant enzyme activities and increased levels of antioxidant compounds were observed, yet damage to biomolecules was also observed in experienced rats. During aging changes in oxidative stress were observed. We found higher activities of antioxidant enzymes, higher amounts of antioxidants, and more damage at six months of age among experienced animals than among naïve animals. Similar antioxidant activities and levels, and damage were found between the groups at twenty-four months of age. These results add comprehensive data regarding changes in oxidative stress during aging, and suggest an explanation for the costs of reproduction.

Inflammatory and oxidative stress markers after intravenous insulin in percutaneous coronary intervention with stent in type 2 diabetes mellitus: a randomized controlled trial.

CONTEXT/OBJECTIVE: The objective of the study was to evaluate the effects of normalizing glycemia through iv insulin per 24 h on markers of oxidative stress and inflammation in patients with diabetes submitted to percutaneous coronary intervention (PCI) with stent. PATIENTS/METHODS: This was a prospective, open-label, randomized controlled trial, comparing continuous iv insulin per 24 h targeting glycemia less than 110 mg/dl iv insulin treatment (IIT; n = 35) to standard treatment (ST; n = 35, regular insulin if glycemia was greater than 200 mg/dl). Blood samples for glycemia, glycated hemoglobin, lipids, inflammatory markers [C-reactive protein (CRP), soluble CD40 ligand, IL-6, and endothelin 1 (ET-1)] and oxidative stress (total antioxidant status, carbonyl) were collected immediately after and 24 h after PCI. RESULTS: Seventy patients were included. Mean age was 60.5 ± 10 yr, 60% were men, glycated hemoglobin was 8.1 ± 1.8 (IIT) vs. 7.6 ± 1.6% (ST) (P = 0.39). The intensive insulin group had lower glycemia (P = 0.006) and higher insulinemia (P < 0.001). Insulin did not change CRP [4.5 (2.1-11.7) vs. 6.8 (2.4-10.3), P = 0.35], soluble CD40 ligand [402 (191-843) vs. 610 (230-1200), P = 0.68], IL-6 [6.21 (3.1.-10.4) vs. 10.37 (5.9-15.3), P = 0.09], and ET-1 [1.02 (0.7-1.8) vs. 1.10 (0.7-1.9), P = 0.657]. CRP, IL-6, and ET-1 increased after PCI in both groups (P < 0.05). No change was observed on protein oxidation (carbonyl, P = 0.70; total antioxidant status, P = 0.33). There was a positive correlation between CRP and glycemia (r = 0.29, P = 0.002). CONCLUSIONS: Continuous iv insulin for 24 h increased insulin levels and prevented hyperglycemia. Insulin infusion did not prevent the rise in inflammatory and oxidative stress markers, and no differences were observed between IIT and ST after PCI with a stent.

Differential resistance to oxidants and production of hydrolytic enzymes in Candida albicans.

Resistance to the toxic effects of reactive oxygen species produced by phagocytes and production of hydrolytic enzymes are important aspects of Candida albicans virulence. In this report, we compared twelve C. albicans isolates for their in vitro capacity to resist oxidants-hydrogen peroxide, menadione and paraquat; and to produce hydrolytic enzymes-phospholipase and protease. Different C. albicans isolates showed different degrees of resistance to oxidants as well as differences in production of hydrolytic enzymes. Resistance to oxidative stress did not correlate with production of hydrolytic enzymes. This reinforces the view that C. albicans differentially regulates the expression of virulence factors in response to local environmental conditions.

Response to oxidative stress in eight pathogenic yeast species of the genus Candida.

In the course of an infection, the formation of reactive oxygen species by phagocytes and the antioxidant defense mechanisms of microorganisms play a crucial role in pathogenesis. In this study, isolates representing 8 pathogenic Candida species-Candida albicans, Candida dubliniensis, Candida famata, Candida glabrata, Candida guilliermondii, Candida krusei, Candida parapsilosis and Candida tropicalis-were compared with regard to their resistance to oxidative stress in vitro. We evaluated degree of resistance, induction of oxidative damage, capacity to adapt, and induction of antioxidant enzymes. The species showed variable sensitivity to oxidative attack. C. albicans, C. glabrata, and C. krusei were more resistant to oxidative stress under the conditions tested; C. parapsilosis and C. tropicalis presented medium resistance; and C. dubliniensis, C. famata, and C. guilliermondii were more sensitive. The overall greater resistance to oxidative stress of C. albicans and C. glabrata may provide an advantage to these species, which are the major causative agents of candidiasis.

Pulmonary antioxidant defences and protein damage during the ageing process of both sexes.

The free radical theory holds that the senescence is caused by oxidative damage that results from an imbalance between reactive oxygen and nitrogen species (RONS) and antioxidant defences. Hence, it plays an important role in the field of gerontology. We evaluated, in male and female rats, the activities of the antioxidant enzymes catalase (CAT), glutathione peroxidase (GPx), and total superoxide dismutase (tSOD), as well as oxidative protein damage in pulmonary tissue at 3, 6, 12, and 20 months of age. The results show an increase in the activities of all antioxidant enzymes at 12 months of age in female rats, suggesting an association with the reproductive life cycle. Protein damage in female pulmonary tissues did not change significantly throughout the ageing process. In male rats, the activity of GPx in 20 months of age showed an inter-gender increase, while the tSOD and GPx showed higher activities in 20 months of age in the intra-gender analysis. The male lung showed higher protein damage at 6 months of age. These findings suggest that antioxidant enzymatic activity is connected to the reproductive life cycle.

Blood antioxidant parameters in sickle cell anemia patients in steady state.

Sickle cell anemia (SCA) is a hereditary disorder with higher potential for oxidative damage due to chronic redox imbalance in red cells. We measured antioxidant enzymes including catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD). We also determined oxidative damage of proteins in hemolysate of red blood cells (RBCs) and plasma (carbonyl assay). We characterized the membrane damage in terms of lipid peroxidation by accumulation of malonaldehyde (MDA) by HPLC in 30 healthy controls and 20 SCA patients in steady-state condition. Twenty (9 males/11 females) adult SCA patients and 30 healthy controls were studied. All patients and control subjects had antioxidant (CAT, GPx, SOD, carbonyl and MDA) and hematological parameters done. Our data show that SCA patients had significant higher GPx and SOD activities than healthy controls. Carbonyl assay was noted in plasma but not in hemolysate. An enhanced production of MDA was observed in the serum of SCA patients. Our data support the growing evidence that patients with SCA are subjected to chronic oxidative stress and are able to oxidative damage in biological macromolecules such as proteins and lipids.

Antioxidant enzymes activities and protein damage in rat brain of both sexes.

The theory of free radicals and accumulation of damages suggests that the reactive species of oxygen play a key role in the context of aging. Thus, for the best understanding of the aging process, the study of antioxidant defenses has to be considered as part of gerontology. The present work evaluated the enzymatic activity of the enzymes catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD), and measured the amount of oxidative damage in proteins (carbonyl groups) in brains of rats of both sexes in the ages of 3-, 6-, 12- and 20-months. The results suggest that the patterns of activity and accumulation of damages can be sex-specific and related to the cycle of reproductive life of the organism.

High levels of catalase in sod mutants of Saccharomyces cerevisiae in high aeration conditions

Saccharomyces cerevisiae deficientes nos genes da superóxido dismutase (mutantes sod1D, sod2De sod1Dsod2D) cultivados em fase estacionária sob condições de alta aeração foram submetidos ao estresse com peróxido de hidrogênio (H2O2). Todos os mutantes mostraram-se sensíveis após o tratamento com o H2O2. A enzima glutationa peroxidase (GPx) apresentou níveis significativamente mais baixos nos simples mutantes sod1D e sod2D que na cepa selvagem sem tratamento. Após, a exposição a diferentes concentrações de H2O2, os níveis da glutationa peroxidase aumentaram no duplo mutante sod1Dsod2D e no simples mutante sod2D, enquanto o mutante sod1D manteve baixa atividade da glutationa peroxidase. O mutante sod2D demonstrou atividade da catalase similar a da cepa selvagem sem tratamento, enquanto foi observado que a atividade da catalase decresceu em condições de baixa aeração. O duplo mutante sod1Dsod2D apresentou baixa atividade da catalase mesmo sem tratamento. Os níveis da catalase foram maiores em condições de alta aeração do que em condições microaerófilas, inclusive o duplo mutante sod1Dsod2D contém menos H2O2, visto que, a SOD catalisa a clivagem do superóxido produzindo H2O2 e oxigênio. Nós sugerimos neste trabalho que a catalase não é essencial para os mutantes sod sob condições normais, mas ela participa de uma importante via na aquisição da tolerância ao estresse oxidativo induzido por condições de alta aeração.