[Carbohydrate restriction in the larval diet causes oxidative stress in adult insects of Drosophila melanogaster]

The influence of 20 and 1% glucose and fructose, which were components of larval diet, on the level of oxidized proteins and lipids, low molecular mass antioxidant content as well as activities of antioxidant and associated enzymes in adult fruit fly Drosophila melanogaster were investigated. The restriction of carbohydrates in larval diet leads to oxidative stress in adult insects. It is supported by 40-50% increased content of protein carbonyl groups and by 60-70% decreased level of protein thiol groups as well as by a 4-fold increase of lipid peroxide content in 2-day-old flies of both sexes, developed on the diet with 1% carbohydrates. Oxidative stress, induced by carbohydrate restriction of the larval diet, caused the activation of antioxidant defence, differently exhibited in male and female fruit flies. Caloric restriction increased activity of superoxide dismutase and thioredoxin reductase associating only in males with 2-fold higher activity of NADPH-producing enzymes--glucose-6-phosphate dehydrogenase and isocitrate dehydrogenase. Carbohydrate restriction in the larval diet caused the increase of uric acid content, but the decrease in catalase activity in males. In females the values of these parameters were changed in opposite direction compared with males. The obtained results let us conclude the different involvement of low molecular mass antioxidants, glutathione and uric acid, and antioxidant enzyme catalase in the protection of male and female fruit fly macromolecules against oxidative damages, caused by calorie restriction of larval diet.

[Mild oxidative stress in fruit fly Drosophila melanogaster caused by products of sucrose hydrolysis]

The influence of 6% sucrose and equimolar mixture of glucose and fructose in larva diet on the level of oxidized proteins and lipids as well as the activity of antioxidant and associated enzymes in adult fruit fly Drosophila melanogaster was investigated. Larva growing on the diet with sucrose led to the mild oxidative stress development in adult insects, which was differently expressed in both sexes. In males mainly molecules of proteins were subjected to oxidative damages, whereas in females--lipid molecules. This is evidenced by 77% increased content of protein carbonyl groups and decreased (by 40%) level of protein SH-groups in males fed on sucrose. In females fed on sucrose the content of lipid peroxides was by 44% higher, than in individuals, hold on the diet with equimolar mixture of glucose and fructose. The oxidative stress in females was accompanied with increased activity of catalase, superoxide dismutase and thiredoxin reductase by 30, 15 and 34%, respectively. The obtained results suggest that uptake mode of glucose and fructose affects free radical processes in fruit flies.

Effect of short-term salt stress on oxidative stress markers and antioxidant enzymes activity in tocopherol-deficient Arabidopsis thaliana plants

Changes of carotenoids and anthocyanins content, lipid peroxidation, and activity of antioxidant enzymes were studied in wild type and tocopherol-deficient lines vte1 and vte4 of Arabidopsis thaliana subjected to 200 mM NaCI during 24 h. The salt stress enhanced the intensity of lipid peroxidation to different extent in all three plant lines. Salt stress resulted in an increase of carotenoid content and activity of catalase, ascorbate peroxidase, guaiacol peroxidase and glutathione reductase in wild type and tocopherol-deficient vte1 mutant. However, the increase in anthocyanins concentration was observed in vte1 mutants only. In vte4 mutant, which contain gamma-tocopherol instead of alpha-tocopherol, the response to salt stress occurred via coordinative action of superoxide dismutase and enzymes of ascorbate-glutathione cycle, in particular, ascorbate peroxidase, glutathione reductase, dehydroascorbate reductase, and glutathione-S-transferase. It can be concluded, that salt stress was accompanied by oxidative stress in three studied lines, however different mechanisms involved in adaptation of wild type and tocopherol-deficient lines to salt stress.

Regulatory protein Yap1 is involved in response of yeast Saccharomyces cerevisiae to nitrosative stress

The goal of this work was to investigate the possible involvement of protein transcription factor Yap1 in regulation of activity of antioxidant enzymes superoxide dismutase and catalase during yeast response to nitrosative stress. It was found that the inactivation of the YAP1 gene, encoding Yap1p, cancelled the activation of superoxide dismutase and catalase by NO-donors. Then, using chimeric protein Yap1-GFP, we found the accumulation of Yap1p in the nucleus in response to nitrosative stress. Therefore, we conclude that these results in combination with previous data clearly demonstrate the involvement of Yap1p in upregulation of superoxide dismutase and catalase in yeast cells in response to nitrosative stress.

Possible pathways involved in activation of catalase and superoxide dismutase with sodium nitroprusside in yeast Saccharomyces cerevisiae

The effect of nitric oxide (*NO) on biological systems depends very much on many circumstances. Nitric oxide can activate redox sensitive pathways that in many cases results in an increase of antioxidant potential of the cell. However, the direct effects of nitric oxide on the activity of principal antioxidant enzymes such as catalase and superoxide dismutase (SOD) have not been studied. In the present work we exploited the yeast model to elucidate a possibility of regulation of the mentioned activity by NO-donor sodium nitroprusside (SNP). We demonstrated that nitric oxide spontaneously generated at SNP decomposition increased the activity of catalase and SOD 1.3 times. Using inhibitors of mRNA (actinomycin D) and protein (cycloheximide) synthesis, the strain deficient in Yap1p, a master regulator coordinating yeast adaptive response to oxidative stress, we have found that these enzymes are up-regulated via synthesis of new molecules at transcription and translation levels. This response is mediated by Yap1p. Despite the increase of SOD activity in yeast cells possibly includes the activation of the present apoprotein by Ccs1p, the ways of nitric oxide regulation of Ccs1p activity are still unclear.

[Activation of enzymes of soxRS-regulon by hydrogen peroxide in Escherichia coli]

A mutant strain (delta soxR), a derivative of strain of Escherichia coli AB 57, was obtained by general transduction. The authors have investigated the effect of oxidative stress on activity of enzymes of regulons oxyR (catalase, peroxidase, glutathione reductase) and soxRS(superoxide dismutase (SOD) and glucose-6-phosphate dehydrogenase (G6PDH) in the donor strain DJ901, recipient strain AB1157 and transductant. Oxidative stress induced by phenasine metasulfate had no effect on activity of the studied enzymes of regulon oxyR in either used strain, and on enzymes of regulon soxRS in DJ901 transductant, but caused an 1.6- and 1.3-fold increase in activity of SOD and G6PDH in AB 1157, respectively. The stress induced by 20 microM hydrogen peroxide in the last strain increased the enzyme activity of both regulons, and SOD activity increased by 28 % and that of G6PDH--by 42%. Under the same kind of stress only SOD activity increased by 20% in the transductant. Possible ways of regulation of activity in enzymes being the components of regulon soxRS are discussed.

[Comparative characteristics of lactate dehydrogenase from the liver and white muscles of common carp (Cyprinus carpio)]

Lactate dehydrogenase from the liver and white muscles of common carp (Cyprinus carpio) was purified by the differential precipitation of supernatants with ammonium sulfate. The results of native electrophoresis of partially purified lactate degydrogenase (LDH) and LDH from some tissues exhibited the different isozyme composition there. However, the kinetic properties of these isozymes from two tissues were not different, except for the value of K(m) for pyruvate, which was 72.5 +/- 11 and 217 +/- 32 microM for the liver and muscle, respectively. LDH from the liver and white muscle had similar pH-dependences with pH-optima for the both LDH activities between 6.75 and 8.00. But studied isozymes demonstrated different thermostability. The partially purified LDH from the liver showed 450% activity after 2 h at 50 degrees C. In contrast, the partially purified LDH from the muscle exhibited about 300% activity after 3 h at 65 degrees C. The heating of partially purified LDH from the muscle caused complete purification of this isozyme.

Effect of VTE1 AND VTE4 gene inactivation on salt stress response in Arabidopsis thaliana

The effect of inactivation of VTE1 and VTE4 genes, encoding enzymes involved in tocopherol biosynthesis, on concentrations of chlorophylls, carotenoids, anthocyanins and activity of catalase and guaiacol peroxidase in Arabidopsis thaliana under salt stress conditions were studied. It was shown, that the inactivation of the VTE4 gene in A. thaliana caused the decrease in concentrations of chlorophylls and carotenoids, and at the same time, inactivation of VTE1 gene resulted in 3.6-fold increase of catalase activity in comparison with the wild type. Under salt stress, the activities of guaiacol peroxidase increased in all investigated plant groups, while the concentrations of carotenoids increased only in the wild type and vte4 mutant line of A. thaliana. Salt stress did not change the concentrations of protein carbonyl groups and activities of catalase.

[Role of Cu, Zn- and Mn-containing superoxide dismutases during the yeast Saccharomyces cerevisiae growing on ethanol and glycerol]

Growth of the yeast Saccharomyces cerevisiae deficient as to superoxidedismutase (SOD) genes in the media containing ethanol or glycerol has been investigated. It was shown that the role of the two isoforms of SOD was different under conditions used in this study. The strain which has only mitochondrial Mn-SOD demonstrated higher velocity of culture growth on ethanol compared with the other strains investigated. In contrast to that, cytosolic Cu, Zn-SOD played more important role under growth on glycerol than Mn-SOD. The levels of carbonyl proteins in SOD-deficient strains grown on glycerol and in the cells of strain producing only Cu, Zn-SOD exposed to inhibitor diethyldithiocarbamate were investigated. The strains lacking Mn-SOD and Cu, Zn-SOD demonstrated virtually the same levels of carbonyl proteins. It is supposed that Cu, Zn-SOD can compensate Mn-SOD and vice versa. Nonlinear correlation between SOD activity and the level of carbonyl proteins was found that indicates to the uncertain role of SOD in protein oxidation.

Comparison of glycolytic NADH oscillations in yeasts Saccharomyces cerevisiae and Saccharomyces carlsbergensis

The possible mechanism of synchronization of NADH oscillations in yeasts were studied. It was shown that the synchronization time depends on cell concentration in suspension. Synchronization of oscillations after acetaldehyde addition was found in Saccharomyces carlsbergensis whereas in S. cerevisiae oscillations were synchronized after adding potassium cyanide. It is possible, that synchronization of oscillations in S. cerevisiae requires low concentration of acetaldehyde and the high acetaldehyde concentration synchronizes oscillations in S. carlsbergensis. In addition, a possible mechanism of synchronization by acetaldehyde in proposed.

[Indices of oxidative stress. 1. TBA-reactive substances and carbonylproteins]

The method of measurement of two oxidative stress indices, TBA-reactive substances and carbonylproteins, in one sample has been proposed using different tissues of common carp. Optimal time of boiling of the preparations with thiobarbituric acid was 60 min. Protein has been solubilized in 6 M guanidine-HCl, or 6 M urea, or 5% sodium dodecylsulphate solutions. Carbonylprotein concentration has been proposed to measure in guanidine-HCl solution and to calculated per protein content in these solutions. The concentration of carbonylproteins rose during incubation of carp kidney preparations with ascorbic acid (0.1-0.5 mM) and ferrous sulphate (2.5-20.0 microM). Incubation of kidney preparations with 0.5 mM ascorbic acid and 20 mM ferrous sulphate showed that the carbonylprotein content has been elevated starting with 60 min incubation and reached 8-fold increase during 120 min. Methodological aspects of oxidative stress indices measuring are discussed.

[Effect of aminotriazole on the activity of catalase and glucose-6-phosphate dehydrogenase in tissues of two frog species--Rana ridibunda and Rana esculenta]

Changes of the activity of catalase and glucose-6-phosphate dehydrogenase (G6PDH) during 48 hrs after intraperitoneal injection of 1.0, 0.5 and 0.1 mg aminotriazole per gram of body weight of two frog species as well as catalase inhibition by aminotriazole in vitro were investigated. Both aminotriazole concentration and species affiliation affected the catalase inhibition. The sensitivity of catalase from different tissues was decreased in the order: liver--kidney--lung--muscle--brain. The constant of half inhibition of lung catalase was significantly lower than that of liver and kidney catalase. The activity of G6PDH of AMT-treated frogs R. esculenta was higher comparing to control group. Possible ways of compensation of antioxidant defense under catalase inhibition are discussed.