Superoxide Dismutase Isozymes Research Articles

MiR398 is involved in the relief of phenanthrene-induced oxidative toxicity in wheat roots

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants and could produce oxidative toxicity to plants. Our previous study has shown that miR398 is involved in response to phenanthrene treatment by targeting CSD1 and CSD2. However, it is not clear which is essential for CSD1 and CSD2 and how miR398 changes. In this study, we performed discontinuous PAGE to separate superoxide dismutase (SOD) isozymes and found that two bands of the cytosolic Cu/Zn-SOD are induced by phenanthrene at day 5 and 7. Low expression of pri-miR398 and high expression of pre-miR398 indicate that the conversion process from pri-miR398 to pre-miR398 is impeded, which causes decrease in mature miR398. The relative expression of CSD1 is entirely up-regulated, further confirming the important role of CSD1 in response to phenanthrene exposure. Besides, the overexpression of WRKY implies its potential function in answering the call from phenanthrene stress. Therefore, it is concluded that the gene silencing of CSD1 recedes due to the biosynthesis inhibition of miR398, causing the increase of SOD activity in response to phenanthrene exposure in wheat roots. Our results are useful not only for better understanding miRNAs regulation in detoxication of reactive oxygen species, but also for alleviating the toxicity to crops caused by PAHs.

Assessment of the effects of zinc on the growth and antioxidant enzymes in Scenedesmus ellipsoideus Chodat

Abstract This study explores the activity of total superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR), biomass accumulation and chlorophyll a content in Scenedesmus ellipsoideus Chodat grown under conditions of varying zinc (Zn) concentrations. In addition, the activity of different SOD isozymes (MnSOD, FeSOD and CuZnSOD) was measured separately to determine the intracellular extent of oxidative stress resulting from Zn toxicity. We found that the activity of FeSOD and MnSOD was induced by lower Zn concentration (2 μg ml−1 and 4 μg ml−1, respectively), whereas CuZnSOD activity was not affected, which indicates that chloroplasts are the first location in S. ellipsoideus cells where superoxide accumulation is accelerated by Zn toxicity. The activity of total SOD and APX was significantly increased by moderate Zn concentrations, probably due to some oxidative stress caused by Zn toxicity. The higher level of Zn application, however, led not only to the inhibition of total SOD and APX activity, but also to the reduction of biomass accumulation and chlorophyll a content. As a result, it can be concluded that the accumulation of superoxide radicals and H2O2 in S. ellipsoideus cells induced by Zn toxicity may be responsible for the reduced growth rate and the impairment of photosynthetic pigments.

SODs involved in the hormone mediated regulation of H2O2 content in Kandelia obovata root tissues under cadmium stress

Cadmium (Cd) pollution in mangrove wetlands has received increasing attention as urbanization expands rapidly. As a dominant mangrove species, Kandelia obovata is highly tolerant to Cd toxicity. Plant hormones and superoxide dismutase (SODs) play critical roles in the response to heavy metal stress in K. obovata roots. Although theirs important influence have been reported, the regulation mechanism between SODs and plant hormones in Cd detoxification by K. obovata roots remains limited. Here, we investigated relationships among SOD, plant hormones, and Cd tolerance in K. obovata roots exposed to Cd. We found that Cd was retained in the epidermis and exodermis of roots, and the epidermis and exodermis had highest hydrogen peroxide (H2O2) content and SOD activity. Similarly, SOD isozymes also exhibited distinct activity in the different parts of root. Overexpressed KoCSD3 and KoFSD2 individually in Nicotiana benthamiana revealed that different SOD members contributed to H2O2 content regulation by promote the activity of downstream antioxidant enzymes under Cd treatment. In addition, assays on the effects of hormones showed that increased endogenous indole-3-acetic acid (IAA) was observed in the cortex and stele, whereas the abscisic acid (ABA) content was enhanced in the epidermis and exodermis in roots during Cd treatment. The results of exogenous hormones treatment indicated that KoFSD2 upregulated under ABA and IAA treatment, but KoCSD3 only induced by ABA stimulation. Taken together, our results reveal the relationship between SODs and plant hormones, which expands the knowledge base regarding KoSODs response to plant hormones and mediating H2O2 concentration under Cd stress.

Responses of Antioxidant Enzymes to Chronic Free-Air Ozone Stress in Rice (Oryza sativa L.) Cultivars with Different Ozone-Sensitivities.

Free-air O3 enrichment was used to investigate the responses of different antioxidant mechanisms in different rice (Oryza sativa L.) cultivars - O3-sensitive hybrid indica (O3-S) cultivars and O3-tolerant conventional japonica (O3-T) cultivars across all growth stages. Elevated [O3] induced increases in reactive oxygen species (ROS) production in O3-S cultivars, which were more pronounced in the later growing stages. In O3-S cultivars, continuous O3 stress decreased catalase (CAT), peroxidase (POD) and glutathione peroxidase (GPX) activities, while in O3-T cultivars, short-term O3 stress decreased superoxide dismutase (SOD), CAT, POD and GPX activities. The same POD isozyme patterns were observed in both O3-S and O3-T cultivars, while SOD and APX isozymes varied by cultivar. The results suggest that O3 tolerance might be improved at different rice development stages through regulating the responses of antioxidant mechanisms to O3 stress.

Differential regulation of defence pathways in aromatic and non-aromatic indica rice cultivars towards fluoride toxicity.

Excessive bioaccumulation of fluoride in IR-64 caused low abscisic acid level, inhibition of polyamine biosynthesis and ascorbate-glutathione cycle but not in Gobindobhog which had higher antioxidant activity. The current study presents regulation of diverse metabolic and molecular defence pathways during fluoride stress in non-aromatic rice variety, IR-64 and aromatic rice variety, Gobindobhog (GB). Increasing concentration of fluoride affected fresh weight, dry weight, vigour index and relative water content to a lesser extent in GB compared to IR-64. GB exhibited lower methylglyoxal accumulation and lipoxygenase activity compared to IR-64 during stress. The level of osmolytes (proline, amino acids and glycine-betaine) increased in both the stressed varieties. The biosynthesis of higher polyamines was stimulated in stressed GB. IR-64 accumulated higher amount of putrescine due to degradation of higher polyamines as supported by gene expression analysis. Unlike IR-64, GB efficiently maintained the ascorbate-glutathione cycle due to much lower fluoride bioaccumulation, compared to IR-64. GB adapted to fluoride stress by strongly inducing guaiacol peroxidase, phenylalanine ammonia lyase and a novel isozyme of superoxide dismutase. While GB accumulated higher abscisic acid (ABA) level during stress, IR-64 exhibited slow ABA degradation which enabled induction of associated osmotic stress-responsive genes.Unlike GB, ABA-independent DREB2A was downregulated in stressed IR-64. The research illustrates varietal differences in the defence machinery of the susceptible variety, IR-64, and the well adapted cultivar, GB, on prolonged exposure to increasing concentrations of fluoride.

Functional assessment of microbial superoxide dismutase isozymes suggests a differential role for each isozyme

Microbes can have multiple enzymes that are able to catalyse the same enzymatic reactions but may differ in structure. These are known as isozymes. It is assumed that isozymes have the same functional role for cells. Contrary to this assumption, we hypothesised that isozymes can confer different functions for microbial cells despite catalysing the same reactions. To test this hypothesis, we studied the role of superoxide dismutases (SOD) in Klebsiella pneumoniae, the causative agent of several nosocomial and community-acquired infections, in infection relevant assays. SODs are responsible for detoxification of toxic superoxide radicals. K. pneumoniae genome contains three superoxide dismutase genes, sodA, sodB, and sodC coding for Mn-, Fe- and CuZn- co-factored SODs, respectively. By creating and testing single, double, and triple SOD mutants, we investigated the regulatory interactions among SOD and determined the role of each isozyme in oxidative stress resistance, biofilm formation, cell morphology, metabolism, and in vivo colonization and persistence. Our results demonstrate that SOD isozymes in K. pneumoniae have unique roles beyond oxidative stress resistance, and there is a regulatory interplay among SODs.

Enzymatic Analysis of Superoxide Dismutase (SOD) from Hordeum vulgare: Its Role in Drought Stress Tolerance

Superoxide dismutases (SODs) are ubiquitous metalloenzymes that constitute the first line of defense against reactive oxygen species. The role of SOD in neutralizing free radical production has already been documented. In the present investigation we have attempt to study kinetic properties of SODs in three drought sensitive and drought resistant varieties of H. vulgare. The results demonstrated that SOD displayed decreased affinities of substrate binding to their corresponding enzymes under drought conditions. The SOD isozymes profile was also analyzed and it was found that under drought conditions the only two SOD isozymes expressed as against three isozymes expressed under control. These data suggest that the decreased substrate binding affinity to SODs as well as decrease in one isozyme band of SOD under drought condition may be responsible for resistance. These findings may be used to develop drought resistance varieties of other crops.

Investigation into the relationship among Cd bioaccumulation, nutrient composition, ultrastructural changes and antioxidative metabolism in lettuce genotypes under Cd stress

Lettuce (Lactuca sativa L.) is known to have high cadmium (Cd) concentrations in its shoots, which makes it necessary to protect against Cd toxicity. Understanding Cd-induced physiological responses in lettuce plants can contribute to the definition of useful strategies to decrease Cd uptake. This study aimed to gain new insights into Cd-induced stress by measuring Cd bioaccumulation, nutrient composition, anatomical and ultrastructural changes, and antioxidative metabolism in three lettuce genotypes characterized as having different degrees of Cd tolerance (Vanda = low, Lidia = medium and Stela = high). Plants were grown hydroponically with Cd concentrations of 0.0 and 0.1 or 0.5 μmol L−1, for 30 days. Cadmium uptake in the lettuce genotypes assayed is controlled by the root/shoot ratio, higher root/shoot ratios allowing greater Cd uptake. The Fe and Ni content increased in shoots of the genotype Lidia, which could be associated with a decrease in oxidative stress in chloroplasts due to superoxide dismutase (SOD) isozyme activity. Cadmium-induced oxidative stress is associated with de-structuring of the phloem and xylem in roots, and starch grain and plastoglobule accumulation in chloroplasts. Lettuce genotypes that presented higher SOD and ascorbate peroxidase (APX) activity presented better preserved anatomical structures. These results suggest that genotypes with less efficient antioxidant defence in the roots tend to take up more Cd, increasing root-to-shoot Cd translocation.

Relationship of ROS accumulation and superoxide dismutase isozymes in developing anther with floret fertility of rice under heat stress

High temperature (HT) at meiosis stage is one of most important environment constraint affecting spikelet fertility and rice yield. In this paper, the effects of HT exposure at meiosis stage on the ROS (reactive oxygen species) accumulation, various superoxide dismutase (SOD, EC1.15.1.11) isozymes in developing anther, and its relationship with HT-induced decline in pollen viability and floret fertility were investigated by using four rice cultivars differing in heat tolerance under well-controlled climatic condition. Results showed that HT exposure significantly increased ROS level and malondialdehyde (MDA) content in rice anther, and this occurrence was strongly responsible for the HT-induced decline in pollen viability and harmful effect of HT adversity on floret fertility. However, the increased extent of ROS concentration in rice anther under HT exposure was greatly variable, depending on both the intensity and duration of HT exposure and different rice cultivars used. The SOD and CAT activities of HT-sensitive cultivars decreased more profoundly than those of HT-tolerant cultivars under the same HT regimes. Among various types of SOD enzymes, Cu/Zn–SODa expressed highly in rice anther and responded sensitively to HT exposure, while Cu/Zn–SODb expressed weakly in rice anther and preferentially in rice leaves. HT exposure suppressed the expression of Cu/Zn–SODa in developing anther, which was closely associated with the down-regulated transcripts of cCu/Zn–SOD1 gene. Hence, Cu/Zn–SODa may play a central role in the regulation of total SOD activity and ROS detoxification in rice anther as affected by HT exposure at meiosis stage.

Alleviation of Cr(VI)-induced oxidative stress in maize (Zea mays L.) seedlings by NO and H2S donors through differential organ-dependent regulation of ROS and NADPH-recycling metabolisms

Chromium (Cr) contamination in soil is a growing concern in relation to sustainable agricultural production and food safety. Nitric oxide (NO) and, more recently, hydrogen sulfide (H2S) are considered to be new signalling molecules with biotechnological applications in the agronomical sector. Using 9-day-old maize (Zea mays) seedlings exposed to 200μM Cr(VI), the potential mitigating effects of exogenous NO and H2S on chromium-induced stress in maize seedlings were investigated in roots, cotyledons and coleoptiles. Analysis of Cr content, lipid peroxidation, antioxidant enzymes (catalase and superoxide dismutase isozymes), peroxisomal H2O2-producing glycolate oxidase and the main NADPH-regenerating system revealed that chromium causes oxidative stress, leading to a general increase in these activities in coleptiles and roots, with the latter organ being the most affected. However, cotyledons behaved in an opposite manner. Moreover, exogenous applications of NO and H2S to Cr-stressed maize seedlings triggered a significant response, involving the virtual restoration of the values for all these activities to those observed in unstressed seedlings, although their specific impact on ROS and NADPH-recycling metabolisms depends on the seedling organ involved. Taken together, the data indicate that gas transmitters, NO and H2S, which act as a defence against the negative effects of hexavalent chromium contamination, are alternative compounds with potential biotechnological applications.

Mechanical wounding promotes local and long distance response in the halophyte Cakile maritima through the involvement of the ROS and RNS metabolism

Mechanical wounding in plants, which are capable of generating defense responses possibly associated with nitro-oxidative stress, can be caused by (a)biotic factors such as rain, wind, herbivores and insects. Sea rocket (Cakile maritima L.), a halophyte plant belonging to the mustard family Brassicaceae, is commonly found on sandy coasts throughout Europe. Using 7-day-old Cakile maritima L. seedlings, mechanical wounding was induced in hypocotyls by pinching with a striped-tip forceps; after 3 h, several biochemical parameters were analyzed in both the damaged and unwounded organs (green cotyledons and roots). We thus determined NO production, H2O2 content, lipid oxidation as well as protein nitration patterns; we also identified several antioxidant enzymes including catalase, superoxide dismutase (SOD) isozymes, peroxidases, ascorbate-glutathione cycle enzymes and NADP-dehydrogenases. All these parameters were differentially modulated in the damaged (hypocotyls) and unwounded organs, which clearly indicated an induction of CuZnSOD V in the three organs, an increase in protein nitration in green cotyledons and an induction of NADP-isocitrate dehydrogenase activity in roots. On the whole, our results indicate that the wounding of hypocotyls, which showed an active ROS metabolism and oxidative stress, causes long-distance signals that also trigger responses in unwounded tissues with a more active RNS metabolism. These data therefore confirm the existence of local and long-distance responses which counteract negative effects and provide appropriate responses, enabling the wounded seedlings to survive.

Ten-eleven translocation 1 functions as a mediator of SOD3 expression in human lung cancer A549 cells

Superoxide dismutase (SOD) 3, one of the SOD isozymes, plays a pivotal role in extracellular redox homeostasis. The expression of SOD3 is regulated by epigenetics in human lung cancer A549 cells and human monocytic THP-1 cells; however, the molecular mechanisms governing SOD3 expression have not been elucidated in detail. Ten-eleven translocation (TET), a dioxygenase of 5-methylcytosine (5mC), plays a central role in DNA demethylation processes and induces target gene expression. In the present study, TET1 expression was abundant in U937 cells, but its expression was weakly expressed in A549 and THP-1 cells. These results are consistent with the expression pattern of SOD3 and its DNA methylation status in these cells. Moreover, above relationship was also observed in human breast cancer cells, human prostate cancer cells, and human skin fibroblasts. The overexpression of TET1-catalytic domain (TET1-CD) induced the expression of SOD3 in A549 cells, and this was accompanied by the direct binding of TET1-CD to the SOD3 promoter region. Furthermore, in TET1-CD-transfected A549 cells, the level of 5-hydroxymethylcytosine within that region was significantly increased, whereas the level of 5mC was decreased. The results of the present study demonstrate that TET1 might function as one of the key molecules in SOD3 expression through its 5mC hydroxylation in A549 cells.

Physiological mechanism of programmed cell death aggravation and acceleration in wheat endosperm cells caused by waterlogging

Wheat (Triticum aestivum L.) is one of the world’s three major food crops, the previous studies have indicated that the development of wheat endosperm cells underwent a special programmed cell death (PCD) and it could be accelerated by waterlogging. Hua 8 wheat cultivar (waterlogging tolerant) and Hua 9 (waterlogging sensitive) were used to reveal the physiological mechanism in this study. The results showed that after 7 days waterlogging treatment (DWT), the malondialdehyde (MDA) and O2 − (superoxide anion-free radical) were increased in both endosperms, especially in Hua 9 endosperm. Content of hydrogen peroxide (H2O2) increased significantly in both endosperms at 12 days after flowering (DAF) and 15 DAF. Proline, soluble sugar, and protein contents in Hua 8 endosperm were increased, nevertheless, the soluble sugar and proline contents declined in Hua 9 endosperm. The activities of superoxide dismutase (SOD) were induced in both endosperms, especially in Hua 8, while showed different change trends in activities of peroxidase (POD) and catalase (CAT). The SOD isozyme spectrogram appeared a new band, and CAT added two bands in Hua 8 endosperm after 7 DWT. CAT isozyme activity was increased markedly, but SOD isozyme in Hua 9 endosperm showed no significant effect by waterlogging stress. Above all, the accumulation of MDA, O2 −, and H2O2 in wheat endosperm after waterlogging led to the aggravation of PCD progress. Compared to Hua 8, more reactive oxygen species (ROS) accumulated in Hua 9 endosperm after waterlogging, combined with the weak ROS scavenging enzyme activities, in addition to the low osmotic pressure accelerated the PCD progress.

Erratum to: Superoxide dismutase and catalase: tissue activities and relation with age in the long-lived species Margaritifera margaritifera

Free radicals are extremely reactive and produce damage and modify cell functions. Furthermore, superoxide dismutase and catalase are believed to play a key role in the enzymatic defence of the cells. Indeed, some authors have argued that reduced free-radical damage could explain increased longevity. Margaritifera margaritifera is one of the longest-lived animals in the world (up to 100-200 years). Furthermore, this organism may serve as a useful model for gerontologists interested in exploring the mechanisms that promote long life and the slowing of senescence. The present study estimated for the first time individual enzymatic activity for superoxide dismutase isozymes (Cu,Zn-SOD and Mn-SOD) and catalase in tissue preparations of gills, digestive glands and mantles of two natural populations of M. margaritifera. Superoxide dismutase activities showed significant differences in the tissues analysed of specimens from the same river and in specimens from different rivers for the same tissue. Catalase activity levels also showed significant variation, but differences among tissues, within tissues or between rivers were of relatively little interest. We failed to find any relationship between individual enzymatic activities and the age estimated for each mussel. Indeed, the wide variation found in activity levels can be principally interpreted as an adaptation to the unpredictable and changing nature of freshwater natural habitats.

Superoxide dismutase and catalase: tissue activities and relation with age in the long-lived species Margaritifera margaritifera.

Free radicals are extremely reactive and produce damage and modify cell functions. Furthermore, superoxide dismutase and catalase are believed to play a key role in the enzymatic defence of the cells. Indeed, some authors have argued that reduced free-radical damage could explain increased longevity. Margaritifera margaritifera is one of the longest-lived animals in the world (up to 100-200 years). Furthermore, this organism may serve as a useful model for gerontologists interested in exploring the mechanisms that promote long life and the slowing of senescence. The present study estimated for the first time individual enzymatic activity for superoxide dismutase isozymes (Cu,Zn-SOD and Mn-SOD) and catalase in tissue preparations of gills, digestive glands and mantles of two natural populations of M. margaritifera. Superoxide dismutase activities showed significant differences in the tissues analysed of specimens from the same river and in specimens from different rivers for the same tissue. Catalase activity levels also showed significant variation, but differences among tissues, within tissues or between rivers were of relatively little interest. We failed to find any relationship between individual enzymatic activities and the age estimated for each mussel. Indeed, the wide variation found in activity levels can be principally interpreted as an adaptation to the unpredictable and changing nature of freshwater natural habitats.

Rickettsia parkeri colonization in Amblyomma maculatum: the role of superoxide dismutases.

BackgroundThe Gulf Coast tick (Amblyomma maculatum) is an arthropod vector of Rickettsia parkeri, the causative agent of American boutonneuse fever and an infectious agent of public health significance. In this study, we evaluated the biological significance of the superoxide dismutases (SODs) of A. maculatum in hematophagy and R. parkeri colonization within the tick host.MethodsAn RNA interference approach was used to measure the functional roles of tick SODs (Cu/Zn-SOD and Mn-SOD) in R. parkeri colonization of the tick vector. Total microbial load, R. parkeri infection rate, and compensatory mechanisms by tick genes were examined using quantitative polymerase chain reaction (PCR) and quantitative reverse-transcriptase PCR assays. SOD enzymatic activity assays and malondialdehyde (MDA) lipid peroxidation were employed to determine the redox states in the tick tissues.ResultsKnockdown of the Cu/Zn-SOD gene caused the upregulation of Mn-SOD in transcript levels. Single and dual knockdowns of the SOD genes caused an increase in MDA lipid peroxidation while SOD enzymatic activities did not show a significant change. Mn-SOD knockdown resulted in a substantial increase in the microbial load; however, Cu/Zn-SOD transcript depletion prompted an upsurge in the midgut bacterial load, and significantly decreased the bacterial load in salivary gland tissues. Additionally, Cu/Zn-SOD transcript silencing led to significantly fewer R. parkeri DNA copy numbers in both tick tissues (midguts and salivary glands).ConclusionsSOD enzymes play an important function in the regulation of bacterial communities associated with tick vectors and also in the defense mechanisms against the damage caused by reactive oxygen species within the tick. Knockdown experiments increased the levels of total oxidative stress in ticks, revealing the interplay between SOD isozymes that results in the transcriptional regulation of tick antioxidants. Moreover, the tick's Cu/Zn-SOD aids in the colonization of R. parkeri in tick tissues providing evidence of A. maculatum's vectorial success for a spotted fever group rickettsial pathogen.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1579-1) contains supplementary material, which is available to authorized users.

Antioxidant enzymes expression in Pseudomonas aeruginosa exposed to UV-C radiation.

It was well known that, UV-C irradiation increase considerably the reactive oxygen species (ROS) levels in eukaryotic and prokaryotic organisms. In the enzymatic ROS-scavenging pathways, superoxide dismutase (SOD), Catalase (CAT), and peroxidase (POX) were developed to deal with oxidative stress. In this study, we investigated the effects of UV-C radiations on antioxidant enzymes (catalase, superoxide dismutase, and peroxidases) expression in Pseudomonas aeruginosa. Catalase, superoxide dismutase, and peroxidases activities were determined spectrophotometrically. Isozymes of superoxide dismutase were revealed by native gel activity staining method. Lipid peroxidation was determined by measuring malondialdehyde formation. Our results showed that superoxide dismutase, catalase and peroxidase activities exhibited a gradual increase during the exposure time (30 min). However, the superoxide dismutase activity was maximized at 15 min. Native gel activity staining assays showed the presence of three superoxide dismutase isozymes. The iron-cofactored isoform activity was altered after exposure to UV-C stress. These finding suggest that catalase and peroxidase enzymes have the same importance toward UV-C rays at shorter and longer exposure times and this may confer additional protection to superoxide dismutase from damage caused by lipid peroxidation. Moreover, our data demonstrate the significant role of the antioxidant system in the resistance of this important human pathogen.

Berberine-induced changes in protein expression and antioxidant enzymes in melanoma cells

Proteomic identification of differentially expressed proteins after treatment with berberine, a natural alkaloid, was investigated in this study. The 23 differentially expressed proteins, 3 of which were enhanced and 20 were reduced, were associated with diverse biological functions including cell death and molecular chaperone. The proteomic result was also validated by western blot analysis of ezrin, septin, UQCRC1 and elongation factor Tu. Moreover, changes in total activity and isozyme pattern of antioxidant enzymes were examined via activity assay and in-situ activity staining, respectively. Total activities of catalase and superoxide dismutase were enhanced, while those of glutathione peroxidase and glutathione reductase were unchanged by berberine. Taken together, the results showed that berberine elicited alteration of protein expression patterns and signaled the induction of isozyme of catalase and superoxide dismutase in melanoma cells.

Effects of Edaravone on Hippocampal Antioxidants in EL Mice.

The role of oxidative stress in susceptibility to seizures has been the focus of several recent studies. The aim of the present study was to evaluate the antiepileptic effects of the free radical scavenger edaravone on EL mice, a strain that is highly susceptible to convulsive seizures. EL mice were treated intraperitoneally with edaravone or saline for 1 week. The levels of reduced glutathione (GSH), oxidized glutathione (GSSG) and 3 isozymes of superoxide dismutase (SOD) (cytoplasmic copper- and zinc-containing SOD, extracellular SOD, and mitochondrial manganese-containing SOD) were measured in the hippocampus, and electroencephalograms (EEGs) were used to evaluate seizure sensitivity. Hippocampal levels of GSSG were lower in the edaravone group than in the untreated control group, and the GSH/GSSG ratio, Cu/Zn-SOD, and EC-SOD activities were higher in the edaravone group. Edaravone shortened the duration of interictal spike discharges and clinically suppressed epileptic seizures. Edaravone increases antioxidant potency and reduces seizure susceptibility in EL mice, making it a promising novel antiepileptic agent.

Superoxide Dismutase of Micrococcus sp. S2 and Its Involve in Paraquat Detoxification

As an active ingredient of herbicide, paraquat will induce formation of superoxide radicals. The previous research succeeded in isolating paraquat degrading bacteria from peat soil, Micrococcus sp. S2, that tolerant to high concentration of paraquat. An anti-oxidative enzyme, namely superoxide dismutase (SOD, EC.1.15.1.1), was believed to be responsible for the paraquat tolerance. This research was conducted to study the characteristic of the SOD synthesize by Micrococcus sp. S2 and its ability on neutralize superoxide which arise from paraquat reoxidation. To observe the effect of paraquat on Micrococcus sp. S2, the bacteria was grown in 10% Luria Bertani broth medium amended with several concentrations of paraquat, from 0 (control) up to 100 mg/ml. Within incubation time of 72 hours, bacterial growth, activity of superoxide dismutase and paraquat residue were analyzed. The isozymes of superoxide dismutase were distinguished using two kinds of specific inhibitor, namely HO and KCN. 2 2 The results showed that paraquat significantly inhibit the growth of Micrococcus sp. S2. The higher paraquat cocentration in the medium caused the higher growth inhibition. However, the bacteria is still survive in the medium containing toxic herbicide, and this ability was suggested related to superoxide dismutase activity in removing the superoxide radicals. Analysis using gel electrophoresis indicated that at least three types of SOD isozyme were synthesized by Micrococcus sp. S2; they were Ferri-SOD (Fe-SOD), Mangani-SOD (Mn-SOD), and the last one was suspected to be the Cupro Zinc-SOD (CuZn-SOD). The Mangani-SOD was suspected to play an important roles on detoxifying superoxide which arise from paraquat oxidation. Keywords : Micrococcus sp.S2, paraquat, superoxide dismutase, isozymes