Aspects of the structure, function, and applications of superoxide dismutase

The role of Cu/Zn-SOD and Mn-SOD in the immune response to oxidative stress and pathogen challenge in the clam Meretrix meretrix

The copper/zinc superoxide dismutase (Cu/Zn-SOD) and manganese superoxide dismutase (Mn-SOD) could effectively eliminate reactive oxygen species (ROS) and maintain the redox balance of immune system. In the present study, the potential synergy of Cu/Zn-SOD and Mn-SOD in immune system was investigated in the clam Meretrix meretrix. The expression of Cu/Zn-SOD mainly distributed in hepatopancreas and that of Mn-SOD was higher in gill of M. meretrix, and their mRNA and protein activity paralleled with each other. In response to H2O2 challenge, Cu/Zn-SOD mRNA showed significantly higher level at 24 h post-challenge and Mn-SOD mRNA was significantly higher at 12 and 24 h post-challenge in the experimental clams than in the control clams (P<0.05). After injection with Vibrio-parahaemolyticus-related bacterium (MM21), the Cu/Zn-SOD mRNA was significantly up-regulated at 24 h and 48 h post-injection and Mn-SOD mRNA was significantly higher at 24 h post-injection in MM21-injected clams than in control clams (P<0.05), suggesting that both of them might involve in the immune defense to Vibrio challenge. The mRNA expression of Cu/Zn-SOD and Mn-SOD was examined in a Vibrio-resistant population and a control population after MM21 immersion challenge. The increased transcription of Cu/Zn-SOD and Mn-SOD in the resistant population suggested both of them could benefit the immune system to defend against pathogen infection. As expression of Mn-SOD mRNA depended on stimuli and was more easily inducible, its response to H2O2 and Vibrio challenge was earlier than Cu/Zn-SOD. Our study suggested the redox balance might play an important role in M. meretrix to resist pathogen infection.

Genome-based proteomic analysis of Lignosus rhinocerotis (Cooke) Ryvarden sclerotium

Lignosus rhinocerotis (Cooke) Ryvarden (Polyporales, Basidiomycota), also known as the tiger milk mushroom, has received much interest in recent years owing to its wide-range ethnobotanical uses and the recent success in its domestication. The sclerotium is the part with medicinal value. Using two-dimensional gel electrophoresis coupled with mass spectrometry analysis, a total of 16 non-redundant, major proteins were identified with high confidence level in L. rhinocerotis sclerotium based on its genome as custom mapping database. Some of these proteins, such as the putative lectins, immunomodulatory proteins, superoxide dismutase, and aegerolysin may have pharmaceutical potential; while others are involved in nutrient mobilization and the protective antioxidant mechanism in the sclerotium. The findings from this study provide a molecular basis for future research on potential pharmacologically active proteins of L. rhinocerotis.

A novel mechanism of protein thermostability: a unique N-terminal domain confers heat resistance to Fe/Mn-SODs

Superoxide dismutases (SODs), especially thermostable SODs, are widely applied in medical treatments, cosmetics, food, agriculture, and other industries given their excellent antioxidant properties. A novel thermostable cambialistic SOD from Geobacillus thermodenitrificans NG80-2 exhibits maximum activity at 70°C and high thermostability over a broad range of temperatures (20–80°C). Unlike other reported SODs, this enzyme contains an extra repeat-containing N-terminal domain (NTD) of 244 residues adjacent to the conserved functional SODA domain. Deletion of the NTD dramatically decreased its optimum active temperature (OAT) to 30°C and also impaired its thermostability. Conversely, appending the NTD to a mesophilic counterpart from Bacillus subtilis led to a moderately thermophilic enzyme (OAT changed from 30 to 55°C) with improved heat resistance. Temperature-dependant circular dichroism analysis revealed the enhanced conformational stability of SODs fused with this NTD. Furthermore, the NTD also contributes to the stress resistance of host proteins without altering their metal ion specificity or oligomerisation form except for a slight effect on their pH profile. We therefore demonstrate that the NTD confers outstanding thermostability to the host protein. To our knowledge, this is the first discovery of a peptide capable of remarkably improving protein thermostability and provides a novel strategy for bioengineering thermostable SODs.

A novel murrel Channa striatus mitochondrial manganese superoxide dismutase: gene silencing, SOD activity, superoxide anion production and expression

We have reported the molecular characterization including gene silencing, superoxide activity, superoxide anion production, gene expression and molecular characterization of a mitochondrial manganese superoxide dismutase (mMnSOD) from striped murrel Channa striatus (named as CsmMnSOD). The CsmMnSOD polypeptide contains 225 amino acids with a molecular weight of 25 kDa and a theoretical isoelectric point of 8.3. In the N-terminal region, CsmMnSOD carries a mitochondrial targeting sequence and a superoxide dismutases (SOD) Fe domain (28-109), and in C-terminal region, it carries another SOD Fe domain (114-220). The CsmMnSOD protein sequence shared significant similarity with its homolog of MnSOD from rock bream Oplegnathus fasciatus (96%). The phylogenetic analysis showed that the CsmMnSOD fell in the clade of fish mMnSOD group. The monomeric structure of CsmMnSOD possesses 9 α-helices (52.4%), 3 β-sheets (8.8%) and 38.8% random coils. The highest gene expression was noticed in liver, and its expression was inducted with fungal (Aphanomyces invadans) and bacterial (Aeromonas hydrophila) infections. The gene silencing results show that the fish that received dsRNA exhibited significant (P < 0.05) changes in expression when compared to their non-injected and fish physiological saline-injected controls. The SOD activity shows that the activity increases with the spread of infection and decreases once the molecule controls the pathogen. The capacity of superoxide anion production was determined by calculating the granular blood cell count during infection in murrel. It shows that the infection influenced the superoxide radical production which plays a major role in killing the pathogens. Overall, this study indicated the defense potentiality of CsmMnSOD; however, further research is necessary to explore its capability at protein level.

Hypoxanthine uptake by skeletal muscle microvascular endothelial cells from equilibrative nucleoside transporter 1 (ENT1)-null mice: effect of oxidative stress

Adenosine is an endogenous regulator of vascular tone. This activity of adenosine is terminated by its uptake and metabolism by microvascular endothelial cells (MVEC). The predominant transporter involved is ENT1 (equilibrative nucleoside transporter subtype 1). MVEC also express the nucleobase transporter (ENBT1) which is involved in the cellular flux of adenosine metabolites such as hypoxanthine. Changes in either of these transport systems would impact the bioactivity of adenosine and its metabolism, including the formation of oxygen free radicals. MVEC isolated from skeletal muscle of ENT1(+/+) and ENT1(-/-) mice were subjected to oxidative stress induced by simulated ischemia/reperfusion or menadione. The functional activities of ENT1 and ENBT1 were assessed based on zero-trans influx kinetics of radiolabeled substrates. There was a reduction in the rate of ENBT1-mediated hypoxanthine uptake by ENT1(+/+) MVEC treated with menadione or after exposure to conditions that simulate ischemia/reperfusion. In both cases, the superoxide dismutase mimetic MnTMPyP attenuated the loss of ENBT1 activity, implicating superoxide radicals in the response. In contrast, MVEC isolated from ENT1(-/-) mice showed no reduction in ENBT1 activity upon treatment with menadione or simulated ischemia/reperfusion, but they did have a significantly higher level of catalase activity relative to ENT1(+/+) MVEC. These data suggest that ENBT1 activity is decreased in MVEC in response to the increased superoxide radical that is associated with ischemia/reperfusion injury. MVEC isolated from ENT1(-/-) mice do not show this reduction in ENBT1, possibly due to increased catalase activity.

Free-radical first responders: the characterization of CuZnSOD and MnSOD regulation during freezing of the freeze-tolerant North American wood frog, Rana sylvatica

BACKGROUND

The North American wood frog, Rana sylvatica, is able to overcome subzero conditions through overwintering in a frozen state. Freezing imposes ischemic and oxidative stress on cells as a result of cessation of blood flow. Superoxide dismutases (SODs) catalyze the redox reaction involving the dismutation of superoxide (O(2)(-)) to molecular oxygen and hydrogen peroxide.

METHODS

The present study investigated the regulation of CuZnSOD and MnSOD kinetics as well as the transcript, protein and phosphorylation levels of purified enzyme from the muscle of control and frozen R. sylvatica.

RESULTS

CuZnSOD from frozen muscle showed a significantly higher V(max) (1.52 fold) in comparison to CuZnSOD from the muscle of control frogs. MnSOD from frozen muscle showed a significantly lower Km for O(2)(-) (0.66 fold) in comparison to CuZnSOD from control frogs. MnSOD from frozen frogs showed higher phosphorylation of serine (2.36 fold) and tyrosine (1.27 fold) residues in comparison to MnSOD from control animals. Susceptibility to digestion via thermolysin after incubation with increasing amount of urea (C(m)) was tested, resulting in no significant changes for CuZnSOD, whereas a significant change in MnSOD stability was observed between control (2.53 M urea) and frozen (2.92 M urea) frogs. Expressions of CuZnSOD and MnSOD were quantified at both mRNA and protein levels in frog muscle, but were not significantly different.

CONCLUSION

The physiological consequence of freeze-induced SOD modification appears to adjust SOD function in freezing frogs.

GENERAL SIGNIFICANCE

Augmented SOD activity may increase the ability of R. sylvatica to overcome oxidative stress associated with ischemia.

Isolation and in silico analysis of Fe-superoxide dismutase in the cyanobacterium Nostoc commune

Cyanobacteria are known to endure various stress conditions due to the inbuilt potential for oxidative stress alleviation owing to the presence of an array of antioxidants. The present study shows that Antarctic cyanobacterium Nostoc commune possesses two antioxidative enzymes viz., superoxide dismutase (SOD) and catalase that jointly cope with environmental stresses prevailing at its natural habitat. Native-PAGE analysis illustrates the presence of a single prominent isoform recognized as Fe-SOD and three distinct isoforms of catalase. The protein sequence of Fe-SOD in N. commune retrieved from NCBI protein sequence database was used for in silico analysis. 3D structure of N. commune was predicted by comparative modeling using MODELLER 9v11. Further, this model was validated for its quality by Ramachandran plot, ERRAT, Verify 3D and ProSA-web which revealed good structure quality of the model. Multiple sequence alignment showed high conservation in N and C-terminal domain regions along with all metal binding positions in Fe-SOD which were also found to be highly conserved in all 28 cyanobacterial species under study, including N. commune. In silico prediction of isoelectric point and molecular weight of Fe-SOD was found to be 5.48 and 22,342.98Da respectively. The phylogenetic tree revealed that among 28 cyanobacterial species, Fe-SOD in N. commune was the closest evolutionary homolog of Fe-SOD in Nostoc punctiforme as evident by strong bootstrap value. Thus, N. commune may serve as a good biological model for studies related to survival of life under extreme conditions prevailing at the Antarctic region. Moreover cyanobacteria may be exploited for biochemical and biotechnological applications of enzymatic antioxidants.

Genome of the avirulent human-infective trypanosome--Trypanosoma rangeli

Background

Trypanosoma rangeli is a hemoflagellate protozoan parasite infecting humans and other wild and domestic mammals across Central and South America. It does not cause human disease, but it can be mistaken for the etiologic agent of Chagas disease, Trypanosoma cruzi. We have sequenced the T. rangeli genome to provide new tools for elucidating the distinct and intriguing biology of this species and the key pathways related to interaction with its arthropod and mammalian hosts.

Methodology/Principal Findings

The T. rangeli haploid genome is ∼24 Mb in length, and is the smallest and least repetitive trypanosomatid genome sequenced thus far. This parasite genome has shorter subtelomeric sequences compared to those of T. cruzi and T. brucei; displays intraspecific karyotype variability and lacks minichromosomes. Of the predicted 7,613 protein coding sequences, functional annotations could be determined for 2,415, while 5,043 are hypothetical proteins, some with evidence of protein expression. 7,101 genes (93%) are shared with other trypanosomatids that infect humans. An ortholog of the dcl2 gene involved in the T. brucei RNAi pathway was found in T. rangeli, but the RNAi machinery is non-functional since the other genes in this pathway are pseudogenized. T. rangeli is highly susceptible to oxidative stress, a phenotype that may be explained by a smaller number of anti-oxidant defense enzymes and heat-shock proteins.

Conclusions/Significance

Phylogenetic comparison of nuclear and mitochondrial genes indicates that T. rangeli and T. cruzi are equidistant from T. brucei. In addition to revealing new aspects of trypanosome co-evolution within the vertebrate and invertebrate hosts, comparative genomic analysis with pathogenic trypanosomatids provides valuable new information that can be further explored with the aim of developing better diagnostic tools and/or therapeutic targets.

Comparative genomics is a powerful tool that affords detailed study of the genetic and evolutionary basis for aspects of lifecycles and pathologies caused by phylogenetically related pathogens. The reference genome sequences of three trypanosomatids, T. brucei, T. cruzi and L. major, and subsequent addition of multiple Leishmania and Trypanosoma genomes has provided data upon which large-scale investigations delineating the complex systems biology of these human parasites has been built. Here, we compare the annotated genome sequence of T. rangeli strain SC-58 to available genomic sequence and annotation data from related species. We provide analysis of gene content, genome architecture and key characteristics associated with the biology of this non-pathogenic trypanosome. Moreover, we report striking new genomic features of T. rangeli compared with its closest relative, T. cruzi, such as (1) considerably less amplification on the gene copy number within multigene virulence factor families such as MASPs, trans-sialidases and mucins; (2) a reduced repertoire of genes encoding anti-oxidant defense enzymes; and (3) the presence of vestigial orthologs of the RNAi machinery, which are insufficient to constitute a functional pathway. Overall, the genome of T. rangeli provides for a much better understanding of the identity, evolution, regulation and function of trypanosome virulence determinants for both mammalian host and insect vector.

Parasitization by Scleroderma guani influences expression of superoxide dismutase genes in Tenebrio molitor

Superoxide dismutase (SOD) is an antioxidant enzyme involved in detoxifying reactive oxygen species. In this study, we identified genes encoding the extracellular and intracellular copper-zinc SODs (ecCuZnSOD and icCuZnSOD) and a manganese SOD (MnSOD) in the yellow mealworm beetle, Tenebrio molitor. The cDNAs for ecCuZnSOD, icCuZnSOD, and MnSOD, respectively, encode 24.55, 15.81, and 23.14 kDa polypeptides, which possess structural features typical of other insect SODs. They showed 20-94% identity to other known SOD sequences from Bombyx mori, Musca domestica, Nasonia vitripennis, Pediculus humanus corporis, and Tribolium castaneum. Expression of these genes was analyzed in selected tissues and developmental stages, and following exposure to Escherichia coli and parasitization by Scleroderma guani. We recorded expression of all three SODs in cuticle, fat body, and hemocytes and in the major developmental stages. Relatively higher expressions were detected in late-instar larvae and pupae, compared to other developmental stages. Transcriptional levels were upregulated following bacterial infection. Analysis of pupae parasitized by S. guani revealed that expression of T. molitor SOD genes was significantly induced following parasitization. We infer that these genes act in immune response and in host-parasitoid interactions.

Activity of melatonin against Leishmania infantum promastigotes by mitochondrial dependent pathway

Visceral leishmaniasis, a potentially fatal disease, remains a major international health problem. Only a limited number of effective antileishmanial agents are available for chemotherapy, and many of them are expensive with severe side effects or have a markedly reduced effectiveness due to the development of drug resistance. Hence, there is a genuine need to develop a novel effective and less toxic antileishmanial drug. Melatonin, a neurohormone found in animals, plants, and microbes, can participate in various biological and physiological functions. Several in vitro or in vivo studies have reported the inhibitory effect of melatonin against many parasites via various mechanisms, including modulation of intracellular concentrations of calcium in the parasite and/or any other suggested mechanism. Importantly, many of available antileishmanial drugs have been reported to exert their effects by disrupting calcium homeostasis in the parasite. The objective of the present study was to test the efficacy of exogenous melatonin against Leishmania infantum promastigotes in vitro. Interestingly, melatonin not only demonstrated a significant antileishmanial activity of against promastigote viability in tested cultures but was also accompanied by an alteration of the calcium homeostasis of parasite mitochondrion, represented by earlier mitochondrial permeability transition pore opening, and by changes in some mitochondrial parameters are critical to parasite survival. These pioneering findings suggest that melatonin may be a candidate for the development of novel effective antileishmanial agents either alone or in associations with other drugs.

Effect of choline on antioxidant defenses and gene expressions of Nrf2 signaling molecule in the spleen and head kidney of juvenile Jian carp (Cyprinus carpio var. Jian)

The present work evaluates the effects of various levels of dietary choline on antioxidant defenses and gene expressions of Nrf2 signaling molecule in spleen and head kidney of juvenile Jian carp (Cyprinus carpio var. Jian). Fish were fed with six different experimental diets containing graded levels of choline at 165 (choline-deficient control), 310, 607, 896, 1167 and 1820 mg kg(-1) diet for 65 days. At the end of the feeding trail, fish were challenged with Aeromonas hydrophila and mortalities were recorded over 17 days. Dietary choline significantly decreased malondialdehyde and protein carbonyl contents in spleen and head kidney. However, anti-superoxide anion and anti-hydroxyl radical activities in spleen and head kidney also decreased. Interestingly, activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and glutathione reductase (GR) in spleen, GPx activity in head kidney, and glutathione contents in spleen and head kidney were decreased with increase of dietary choline levels up to a certain point, whereas, activities of SOD, GST and GR in head kidney showed no significantly differences among groups. Similarly, expression levels of CuZnSOD, MnSOD, CAT, GPx1a, GPx1b and GR gene in spleen and head kidney were significantly lower in group with choline level of 607 mg kg(-1) diet than those in the choline-deficient group. The relative gene expressions of Nrf2 in head kidney and Keap1a in spleen and head kidney were decreased with increasing of dietary choline up to a certain point. However, the relative gene expression of Nrf2 in spleen were not significantly affected by dietary choline. In conclusion, dietary choline decreased the oxidant damage and regulated the antioxidant system in immune organs of juvenile Jian carp.

Molecular cloning, tissue distribution and expression analysis of a manganese superoxide dismutase in blunt snout bream Megalobrama amblycephala

The full-length mitochondrial manganese superoxide dismutase cDNA of blunt snout bream Megalobrama amblycephala (denoted as MamMnSOD) was identified in liver using homology cloning and rapid amplification of cDNA ends. The full-length cDNA of MamMnSOD consisted of 986 bp, with an open reading frame encoding 224 amino acids, a 58-bp 5' untranslated region and a 256-bp 3' untranslated region. The deduced amino acid sequences of MamMnSOD showed high sequence homology to mitochondrial MnSODs from crustaceans. Several motifs, including three mitochondrial MnSOD signatures, amino acid residues responsible for coordinating the manganese, and the putative active center, were almost completely conserved in the deduced amino acid sequences of MamMnSOD. The mRNA expression of MamMnSOD in the tissues of heart, liver, spleen, kidney, muscle, intestine, and gill was examined by quantitative real-time PCR; the highest expression was in the liver. Transcription of MamMnSOD was kinetically modulated in response to nitrite stress in liver and gill tissues. The purified recombinant MamMnSOD showed potent antioxidant activity. Polyclonal antibodies generated from the recombinant product of MamMnSOD were used to specifically identify the native protein in liver of M. amblycephala. Collectively, the findings of this study strongly suggested that MamMnSOD combats oxidative stress and cellular damage induced by nitrite, by detoxifying harmful reactive oxygen species in M. amblycephala.

Genotoxicity of dichlorvos in strains of Drosophila melanogaster defective in DNA repair

Dichlorvos (DDVP), an organophosphate pesticide, is reported to be genotoxic at high concentrations. However, the roles of DNA damage repair pathways in DDVP genotoxicity are not well characterized. To test whether pre- and post-replication pathways are involved, we measured changes in DNA migration (Comet assay) in the midgut cells of Drosophila melanogaster Oregon R+ larvae and in some mutants of pre- (mei-9, mus201, and mus207) and post- (mei-41 and mus209)replication DNA repair pathways. Insects were exposed to environmentally relevant concentrations of DDVP (up to 15ng/ml) for 48h. After insect exposure to 0.15ng/ml DDVP, we observed greater DNA damage in pre-replication repair mutants; effects on Oregon R+ and post-replication repair mutants were insignificant. In contrast, significant DNA damage was observed in the post-replication repair mutants after their exposure to 1.5 and 15ng/ml DDVP. The pre-replication repair mutant mus207 showed maximum sensitivity to DDVP, suggestive of alkylation damage to DNA. We also examined mutants (SOD- and urate-null) that are sensitive to oxidative stress and the results indicate that significant oxidative DNA damage occurs in DDVP-exposed mutants. This study suggests involvement of both pre- and post-replication repair pathways against DDVP-induced DNA damage in Drosophila, with oxidative DNA damage leading to genotoxicity.

Association of antitumor antibiotic Mithramycin with Mn2+ and the potential cellular targets of Mithramycin after association with Mn2+

Mithramycin (MTR), an aureolic acid group of antitumor antibiotic is used for the treatment of several types of tumors. We have reported here the association of MTR with an essential micronutrient, manganese (Mn(2+)). Spectroscopic methods have been used to characterize and understand the kinetics and mechanism of complex formation between them. MTR forms a single type of complex with Mn(2+) in the mole ratio of 2:1 [MTR: Mn(2+)] via a two step kinetic process. Circular dichroism (CD) spectroscopic study indicates that the complex [(MTR)2 Mn(2+)] has a right-handed twist conformation similar in structure with the complexes reported for Mg(2+) and Zn(2+). This conformation allows binding via minor groove of DNA with (G, C) base preference during the interaction with double-stranded B-DNA. Using absorbance, fluorescence, and CD spectroscopy we have shown that [(MTR)2 Mn(2+)] complex binds to double-stranded DNA with an apparent dissociation constant of 32 μM and binding site size of 0.2 (drug/nucleotide). It binds to chicken liver chromatin with apparent dissociation constant value 298 μM. Presence of histone proteins in chromatin inhibits the accessibility of the complex for chromosomal DNA. We have also shown that MTR binds to Mn(2+) containing metalloenzyme manganese superoxide dismutase from Escherichia coli.

Manganese superoxide dismutase plays an important role in the inflammatory process and predicts disease severity and activity in patients with ulcerative colitis

The aim of this study was to investigate the expression pattern of manganese superoxide dismutase (MnSOD) in relation to inflammatory factors in ulcerative colitis (UC) and characterize this enzyme as a newly identified biomarker potentially linked to disease pathogenesis of UC. MnSOD expression was analyzed immunohistochemically in 48 formalin-fixed and paraffin-embedded specimens from patients with UC who had undergone endoscopical biopsy. MnSOD expression was observed in vascular endothelium, macrophages, and polymorphonuclear leukocytes within lamina propria of inflamed mucosa. The patients who did not express MnSOD tended to have stabilization of symptoms, but accompanied with status of inflammation. The MnSOD expression pattern was strongly correlated with disease type. MnSOD was expressed in polymorphonuclear leukocytes of all disease types, but cases of chronically counting and exacerbation type had particularly high frequency of immunopositive cells. MnSOD expression in macrophages was frequently observed in cases of symptom remaining type. The cases with MnSOD expression in the vascular endothelium showed a tendency to express in relapse-remission and exacerbation of symptoms. Immunohistochemical evaluation for MnSOD expression may be useful for predicting disease severity and activity in patients with UC.

Preparation and properties of a calcium(ii)-based molecular chain decorated with manganese(ii) butterfly-like complexes

The room temperature reaction of [Mn₂O₂(bipy)₄](ClO₄)₃ (bipy = 2,2′-bipyridine) with Ca(CHCl₂COO)₂ in methanol produced a yellow crystalline material.

Frataxin deficiency leads to defects in expression of antioxidants and Nrf2 expression in dorsal root ganglia of the Friedreich's ataxia YG8R mouse model

AIMS

Oxidative stress is thought to be involved in Friedreich's ataxia (FRDA), yet it has not been demonstrated in the target neurons that are first to degenerate. Using the YG8R mouse model of FRDA, microarray and neuritic growth experiments were carried out in the dorsal root ganglion (DRG), the primary site of neurodegeneration in this disease.

RESULTS

YG8R hemizygous mice exhibited defects in movement, and DRG neurites had growth defects. Microarray of DRG tissue identified decreased transcripts encoding the antioxidants, including peroxiredoxins, glutaredoxins, and glutathione S-transferase, and these were confirmed by immunoblots and quantitative real-time PCR. Because the decreased gene transcripts are the known targets of the antioxidant transcription factor nuclear factor-E2-related factor-2 (Nrf2), Nrf2 expression was measured; it was significantly decreased at the transcript and protein level in both the DRG and the cerebella of the YG8R hemizygous mouse; further, frataxin expression was significantly correlated with Nrf2 expression. Functionally, in YG8R hemizygous DRG, the total glutathione levels were reduced and explanted cells were more sensitive to the thioredoxin reductase (TxnRD) inhibitor auranofin, a thiol oxidant. In cell models of FRDA, including Schwann and the DRG, frataxin deficiency caused a decreased expression of the Nrf2 protein level in the nucleus, but not a defect in its translocation from the cytosol. Further, frataxin-deficient cells had decreased enzyme activity and expression of TxnRD, which is regulated by Nrf2, and were sensitive the TxnRD inhibitor auranofin.

INNOVATION AND CONCLUSION

These results support a mechanistic hypothesis in which frataxin deficiency decreases Nrf2 expression in vivo, causing the sensitivity to oxidative stress in target tissues the DRG and the cerebella, which contributes to the process of neurodegeneration.

Effect of acute administration of L-tyrosine on oxidative stress parameters in brain of young rats

Tyrosinemia type II, also known as Richner-Hanhart syndrome, is an autosomal recessive inborn error of metabolism caused by a deficiency of hepatic cytosolic tyrosine aminotransferase, and is associated with neurologic and development difficulties in numerous patients. Considering that the mechanisms underlying the neurological dysfunction in hypertyrosinemic patients are poorly known and that studies demonstrated that high concentrations of tyrosine provoke oxidative stress in vitro and in vivo in the cerebral cortex of rats, in the present study we investigate the oxidative stress parameters (enzymatic antioxidant defenses, thiobarbituric acid-reactive substances and protein carbonyl content) in cerebellum, hippocampus and striatum of 30-old-day rats after acute administration of L-tyrosine. Our results demonstrated that the acute administration of L-tyrosine increased the thiobarbituric acid reactive species levels in hippocampus and the carbonyl levels in cerebellum, hippocampus and striatum. In addition, acute administration of L-tyrosine significantly decreased superoxide dismutase activity in cerebellum, hippocampus and striatum, while catalase was increased in striatum. In conclusion, the oxidative stress may contribute, along with other mechanisms, to the neurological dysfunction characteristic of hypertyrosinemia and the administration of antioxidants may be considered as a potential adjuvant therapy for tyrosinemia, especially type II.

Link between oxidative stress and acute brain ischemia

The pathogenesis of acute brain ischemia (ABI) is highly complex and involves multiple mechanisms including free radical generation. Imbalance between the cellular production of free radicals and the ability of cells to defend against them is referred to as oxidative stress. Oxidative stress is one of the mechanisms contributing to neuronal damage, potentially induced through the ABI. Through interactions with a large number of molecules, reactive oxygen species may irreversibly destroy or alter the function of the cellular lipids, proteins, and nucleic acids and initiate cell signaling pathways after cerebral ischemia. Future investigations should focus on the understanding of oxidative stress mechanisms and neuroprotection in order to discover new treatment targets.

Molecular basis of active copper resistance mechanisms in Gram-negative bacteria

Copper is a metallic element that is crucial for cell metabolism; however, in extended concentrations, it is toxic for all living organisms. The dual nature of copper has forced organisms, including bacteria, to keep a tight hold on cellular copper content. This challenge has led to the evolution of complex mechanisms that on one hand enable them to deliver the essential element and on the other to protect cells against its toxicity. Such mechanisms have been found in both eukaryotic and prokaryotic cells. In bacteria a number of different systems such as extra- and intracellular sequestration, enzymatic detoxification, and metal removal from the cell enabling them to survive in the presence of high concentration of copper have been identified. Gram-negative bacteria, due to their additional compartment, need to deal with both cytoplasmic and periplasmic copper. Therefore, these bacteria have evolved intricate and precisely regulated systems which interact with each other. In this review the active mechanisms of copper resistance at their molecular level are discussed.

Identification of immune response-related genes in the Chinese oak silkworm, Antheraea pernyi by suppression subtractive hybridization

Insects possess an innate immune system that responds to invading microorganisms. In this study, a subtractive cDNA library was constructed to screen for immune response-related genes in the fat bodies of Antheraea pernyi (Lepidoptera: Saturniidae) pupa challenged with Escherichia coli. Four hundred putative EST clones were identified by suppression subtractive hybridization (SSH), including 50 immune response-related genes, three cytoskeleton genes, eight cell cycle and apoptosis genes, five respiration and energy metabolism genes, five transport genes, 40 metabolism genes, ten stress response genes, four transcription and translation regulation genes and 77 unknown genes. To verify the reliability of the SSH data, the transcription of a set of randomly selected immune response-related genes were confirmed by semi-quantitative reverse transcription-PCR (RT-PCR) and real-time quantitative reverse transcription-PCR (qRT-PCR). These identified immune response-related genes provide insight into understanding the innate immunity in A. pernyi.

Chunggan extract (CGX), methionine-and choline-deficient (MCD) diet-induced hepatosteatosis and oxidative stress in C57BL/6 mice

In the present study, we aimed to evaluate the hepatoprotective and antioxidant effects of Chunggan extract (CGX) in an animal model of hepatosteatosis. The C57BL/6N mice were fed either methionine- and choline-sufficient (MCS) diet (n = 10) or a methionine- and choline-deficient (MCD) diet (n = 50) for 4 weeks, and then they were treated orally with CGX (100 or 200 mg/kg), ursodeoxycholic acid (80 mg/kg, as a positive control), or distilled water (DW, MCS diet group, and MCD diet group) for the final 2 weeks (once per day). The MCD diet induced severe hepatic injury with the typical features of hepatosteatosis in both serum and hepatic tissues. CGX treatment significantly attenuated these alterations in the serum levels including triglyceride (TG), aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and total bilirubin. Moreover, CGX also efficiently prevented from the hepatic TG accumulation in the hepatic tissue, evidenced by histopathological findings, compared with the MCD diet. In addition, CGX treatment significantly ameliorated the excessive oxidative stress and antioxidant markers in the serum as well as the hepatic levels of reactive oxygen species, the levels of malondialdehyde, the protein carbonyl, and total antioxidant capacity, and the activities of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase. In conclusion, our results indicate the experimental relevance of CGX for potential clinical application in patients with hepatosteatotic disorders and a possible mechanism related to its antioxidant properties.

Ginsenoside Rg3 induces apoptosis in the U87MG human glioblastoma cell line through the MEK signaling pathway and reactive oxygen species

Ginsenoside is known to have potential cancer-preventive activities. The major active components in red ginseng consist of a variety of ginsenosides including Rg3, Rg5 and Rk1, each of which has different pharmacological activities. Among these, Rg3 has been reported to exert anticancer activities through inhibition of angiogenesis and cell proliferation. However, the effects of Rg3 and its molecular mechanism on glioblastoma multiforme (GBM) remain unclear. Therefore, it is essential to develop a greater understanding of this novel compound. In the present study, we investigated the effects of Rg3 on a human glioblastoma cell line and its molecular signaling mechanism. The mechanisms of apoptosis by ginsenoside Rg3 were related with the MEK signaling pathway and reactive oxygen species. Our data suggest that ginsenoside Rg3 is a novel agent for the chemotherapy of GBM.

Redox markers and inflammation are differentially affected by atorvastatin, pravastatin or simvastatin administered before endotoxin-induced acute lung injury

Statins are standard therapy for the treatment of lipid disorders, and the field of redox biology accepts that statins have antioxidant properties. Our aim in this report was to consider the pleiotropic effects of atorvastatin, pravastatin and simvastatin administered prior to endotoxin-induced acute lung injury. Male mice were divided into 5 groups and intraperitoneally injected with LPS (10 mg/kg), LPS plus atorvastatin (10 mg/kg/day; A + LPS group), LPS plus pravastatin (5 mg/kg/day; P + LPS group) or LPS plus simvastatin (20 mg/kg/day; S + LPS group). The control group received saline. All mice were sacrificed one day later. There were fewer leukocytes in the P + LPS and S + LPS groups than in the LPS group. MCP-1 cytokine levels were lower in the P + LPS group, while IL-6 levels were lower in the P + LPS and S + LPS groups. TNF-α was lower in all statin-treated groups. Levels of redox markers (superoxide dismutase and catalase) were lower in the A + LPS group (p < 0.01). The extent of lipid peroxidation (malondialdehyde and hydroperoxides) was reduced in all statin-treated groups (p < 0.05). Myeloperoxidase was lower in the P + LPS group (p < 0.01). Elastance levels were significantly greater in the LPS group compared to the statin groups. Our results suggest that atorvastatin and pravastatin but not simvastatin exhibit anti-inflammatory and antioxidant activity in endotoxin-induced acute lung injury.

Molecular characterization of a manganese superoxide dismutase and copper/zinc superoxide dismutase from the mussel Mytilus galloprovincialis

The full-length cDNA sequences coding respectively for a manganese superoxide dismutase (Mg-MnSOD) and copper/zinc superoxide dismutase (Mg-CuZnSOD) were cloned from Mytilus galloprovincialis. Mg-MnSOD and Mg-CuZnSOD cDNAs encoded a polypeptide of 228 and 211 amino acids, respectively. Sequence analysis indicated Mg-MnSOD was a mitochondrial MnSOD and Mg-CuZnSOD was an intracellular CuZnSOD. Multiple alignment analysis showed that both Mg-MnSOD and Mg-CuZnSOD sequences had the common features conserved in MnSODs and CuZnSODs, respectively. Phylogenetic analysis revealed that Mg-MnSOD clustered together with MnSODs from other mollusks, whereas Mg-CuZnSOD clustered with other mollusk intracellular CuZnSODs with a wider phylogenetic distance. By quantitative real-time RT-PCR (qPCR) analysis, both Mg-MnSOD and Mg-CuZnSOD transcripts were detected in all tissues examined with the highest expression level in hepatopancreas. Following bacterial challenge, the expression level of Mg-MnSOD and Mg-CuZnSOD increased first and subsequently decreased to the original level in hemocytes. In hepatopancreas, Mg-CuZnSOD mRNA was up-regulated significantly at 72 h and 96 h post challenge, while the level of Mg-MnSOD transcript had no significant change. Therefore, Mg-MnSOD and Mg-CuZnSOD expressions were inducible and they were probably involved in the immune response against bacterial challenge. These results suggest that these SODs may play important roles in the immune defense system of M. galloprovincialis and perhaps contribute to the protective effects against oxidative stress in this mussel.

Corrective role of Eugenia jambolana on testicular impairment in streptozotocin-induced diabetic male albino rat: an approach through genomic and proteomic study

The present study was conducted to explore the effect of ethyl acetate fraction of hydro-methanolic (40 : 60) extract of seed of Eugenia jambolana on testicular impairment in diabetic rats. In this respect, biomarkers of oxidative stress, genomics and proteomics in testicular tissue were assessed. Side by side, glycated haemoglobin, serum testosterone, activities of glutamate oxaloacetate transaminase and glutamate pyruvate transaminase in serum, epididymal sperm count including reproductive organosomatic indices were evaluated. Results indicate that a significant recovery (P < 0.05) in the levels of these parameters in fraction-treated diabetic group in comparison with diabetic control. A significant recovery was noted (P < 0.05) in the expression of Bax and Bcl-2 gene towards the control after the treatment of said fraction. Histological study also focused a significant recovery (P < 0.05) in the number of different generation of germ cells at stage VII of spermatogenesis in fraction-treated diabetic group. The said fraction treatment to diabetic rat can recover the activities of serum glutamate oxaloacetate transaminase and glutamate pyruvate transaminase significantly towards the control (P < 0.05). Finally, it may be concluded that ethyl acetate fraction of seed of E. jambolana has a promiseable remedial effect on diabetes-induced testicular dysfunctions in male rat without inducing any metabolic toxicity.

Combined proteomic and molecular approaches for cloning and characterization of copper-zinc superoxide dismutase (Cu, Zn-SOD2) from garlic (Allium sativum)

Superoxide dismutases (SODs; EC 1.15.1.1) are key enzymes in the cells protection against oxidant agents. Thus, SODs play a major role in the protection of aerobic organisms against oxygen-mediated damages. Three SOD isoforms were previously identified by zymogram staining from Allium sativum bulbs. The purified Cu, Zn-SOD2 shows an antagonist effect to an anticancer drug and alleviate cytotoxicity inside tumor cells lines B16F0 (mouse melanoma cells) and PAE (porcine aortic endothelial cells). To extend the characterization of Allium SODs and their corresponding genes, a proteomic approach was applied involving two-dimensional gel electrophoresis and LC-MS/MS analyses. From peptide sequence data obtained by mass spectrometry and sequences homologies, primers were defined and a cDNA fragment of 456 bp was amplified by RT-PCR. The cDNA nucleotide sequence analysis revealed an open reading frame coding for 152 residues. The deduced amino acid sequence showed high identity (82-87%) with sequences of Cu, Zn-SODs from other plant species. Molecular analysis was achieved by a protein 3D structural model.

Effects of the Angiotensin II Type 1 Receptor Antagonist Valsartan on the Expression of Superoxide Dismutase in Hypertensive Patients

The role of oxidative stress in the pathogenesis of vascular diseases such as hypertension has been well recognized. Angiotensin (Ang) II is regarded as a pro-oxidant because it can stimulate the production of reactive oxygen species. The purpose of this study was to evaluate whether treatment with the Ang II type 1 (AT(1)) receptor antagonist valsartan has an antioxidant effect in patients with mild to moderate hypertension. A randomized, double-blind, placebo-controlled study was conducted in 48 stage I and II hypertensive subjects. Patients were followed every 4 weeks for 12 weeks after randomization to valsartan titrated to 80 to 160 mg once or twice daily or matching placebo. The erythrocyte superoxide dismutase (SOD) activity and expression of SOD-mRNA in polymorphonuclear leukocytes were measured before and after treatment. Valsartan showed concentration-dependent inhibition of reactive oxygen species generation in polymorphonuclear leukocytes from hypertensive patients. The erythrocyte superoxide dismutase activity before treatment was more than 2 times higher in hypertensive subjects compared to normal controls. Superoxide dismutase activity decreased significantly after 12 weeks of treatment with valsartan but did not change with placebo. The amount of SOD-mRNA in the polymorphonuclear leukocytes decreased progressively over 3 months in the hypertensive subjects receiving valsartan treatment but did not change in the placebo group. The production of reactive oxygen species is increased in hypertension, and superoxide dismutase activity is increased, presumably as a compensatory mechanism. Treatment with valsartan but not placebo resulted in a progressive down-regulation of SOD-mRNA expression and a reduction in superoxide dismutase activity, suggesting antioxidant activity and a reduction of reactive oxygen species generation. These findings imply that AT(1) receptor antagonists may provide benefits to hypertensive patients beyond blood pressure reduction.

The quantitative proteomic response of Synechocystis sp. PCC6803 to phosphate acclimation

BACKGROUND

Inorganic phosphate (Pi) is a critical nutrient for all life and is periodically limiting in marine and freshwater provinces, yet little is understood how organisms acclimate to fluctuations in Pi within their environment. To investigate whole cell adaptation, we grew Synechocystis sp. PCC6803, a model freshwater cyanobacterium, in 3%, and 0.3% inorganic phosphate (Pi) media. The cells were allowed to acclimate over 60 days, and cells were harvested for quantitative high throughput mass spectrometry-based proteomics using the iTRAQ™ labelling technology.

RESULTS

In total, 120 proteins were identified, and 52 proteins were considered differentially abundant compared to the control. Alkaline phosphatase (APase) activities correlated significantly (p < 0.05) with observed relative PhoA abundances. PstS1 and PstS2 were both observed, yet PstS1 was not differentially more abundant than the control. Phycobilisome protein abundances appeared to be coordinated, and are significantly less abundant in 0.3% Pi than 3% Pi cultures. Also, the central metabolic cell function appears to have shifted towards the production of (NADPH) reducing energy and nucleotide sugars.

CONCLUSIONS

This acclimation response bears strong similarity to the previously reported response to nitrogen deprivation within Synechocystis sp. PCC 6803. However, it also demonstrates some characteristics of desiccation stress, such as the regulation of fatty acids and increased abundance of rehydrin in the 3% Pi culture.

Cloning, expression and characterization of mitochondrial manganese superoxide dismutase from the Whitefly, Bemisia tabaci

A mitochondrial manganese superoxide dismutase from an invasive species of the whitefly Bemisia tabaci complex (Bt-mMnSOD) was cloned and analyzed. The full length cDNA of Bt-mMnSOD is 1210 bp with a 675 bp open reading frame, corresponding to 224 amino acids, which include 25 residues of the mitochondrial targeting sequence. Compared with various vertebrate and invertebrate animals, the MnSOD signature (DVWEHAYY) and four conserved amino acids for manganese binding (H54, H102, D186 and H190) were observed in Bt-mMnSOD. Recombinant Bt-mMnSOD was overexpressed in Escherichia coli, and the enzymatic activity of purified mMnSOD was assayed under various temperatures. Quantitative real-time PCR analysis with whiteflies of different development stages showed that the mRNA levels of Bt-mMnSOD were significantly higher in the 4th instar than in other stages. In addition, the in vivo activities of MnSOD in the whitefly were measured under various conditions, including exposure to low (4 °C) and high (40 °C) temperatures, transfer from a favorable to an unfavorable host plant (from cotton to tobacco) and treatment with pesticides. Our results indicate that the whitefly MnSOD plays an important role in cellular stress responses and anti-oxidative processes and that it might contribute to the successful worldwide distribution of the invasive whitefly.

Characterization of superoxide dismutase 1 (SOD-1) by electrospray ionization-ion mobility mass spectrometry

In this paper, we report nano-electrospray ionization-ion mobility mass spectrometry (nano-ESI-IM-MS) characterization of bovine superoxide dismutase (SOD-1) and human SOD-1 purified from erythrocytes. SOD-1 aggregates are characteristic of amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease in humans that could be triggered by dissociation of the native dimeric enzyme (Cu(2),Zn(2)-dimer SOD-1). In contrast to ESI-MS, nano-ESI-IM-MS allowed an extra dimension for ion separation, yielding three-way mass spectra (drift time, mass-to-charge ratio and intensity). Drift time provided valuable structural information related to ion size, which proved useful to differentiate between the dimeric and monomeric forms of SOD-1 under non denaturing conditions. In order to obtain detailed structural information, including the most relevant post-translational modifications, we evaluated several parameters of the IM method, such as sample composition (10 mM ammonium acetate, pH 7) and activation voltages (trap collision energy and cone voltage). Neutral pH and a careful selection of the most appropriate activation voltages were necessary to minimize dimer dissociation, although human enzyme resulted less prone to dissociation. Under optimum conditions, a comparison between monomer-to-dimer abundance ratios of two small sets of blood samples from healthy control and ALS patients demonstrated the presence of a higher relative abundance of Cu,Zn-monomer SOD-1 in patient samples.

Gastroprotective effects of Leejung-tang, an oriental traditional herbal formula, on ethanol-induced acute gastric injury in rats

Leejung-tang (LJT, Rechu-to in Japanese and Lizhong-tang in Chinese) is an oriental traditional traditional herbal formula. LJT has been used for treatment of gastrointestinal disorders in Korea, Japan, and China for a long time. In present study, we investigated the protective effects of LJT against absolute ethanol induced gastric injuries. Rats in the control group were given PBS orally (5 mL/kg body weight) as the vehicle, and the absolute-ethanol group (EtOH group) received absolute ethanol (5 mL/kg body weight) by oral gavage. Rats in the positive control group were given omeprazole orally (50 mg/kg body weight) 2 h prior to the administration of absolute ethanol. The treatment groups received LJT (400 mg/kg body weight) 2 h prior to absolute ethanol administration. All rats were sacrificed 1 h after receiving the ethanol treatment. The stomach was excised for macroscopic examination and biochemical analysis. The administration of LJT protected gastric mucosa against ethanol-induced acute gastric injury, including hemorrhage and hyperemia. LJT reduced the increase in lipid peroxidation in ethanol-induced acute gastric lesions. LJT increased GSH content and activities of the antioxidant enzymes, catalase, glutathione-S-transferase, glutathione reductase, glutathione peroxidase, and superoxide dismutase. These results indicate that LJT protects gastric mucosa against ethanol-induced acute gastric injury by increasing their antioxidant content. We suggest that LJT can be developed as an effective drug for the treatment of acute gastric injury.

Separation and characterization of superoxide dismutase 1 (SOD-1) from human erythrocytes by capillary electrophoresis time-of-flight mass spectrometry

Cu, Zn-superoxide dismutase (SOD-1) is a homodimeric metalloenzyme that has been related to ALS (amyotrophic lateral sclerosis). The majority of ALS cases are sporadic while approximately 10% are inherited (familial ALS, FALS). Mutations in the amino acid sequence of human SOD-1 cause only 25% of the FALS cases, while the explanation for the rest is not clear yet. In this way, several authors have suggested the importance of posttranslational modifications or dimer dissociation on formation of the characteristic fatal intraneuronal SOD-1 aggregates. In this paper, we used capillary electrophoresis-electrospray mass spectrometry with an accurate mass and high-resolution time-of-flight mass spectrometer (CE-TOF-MS) for separation and characterization of standard bovine SOD-1 and human SOD-1 purified from erythrocytes. Two background electrolytes (BGEs) were used for CE-TOF-MS experiments in positive ion mode. An acidic BGE allowed detection of apo-monomer SOD-1, because the metal ions were completely released during the electrophoretic separation. The better sensitivity at acidic pH was especially interesting to detect different isoforms of human SOD-1. In contrast, a neutral BGE provided enhanced conditions for detection of the fully metalated dimeric and monomeric enzyme, but selecting an appropriate fragmentor voltage value in the TOF analyzer was critical to obtain reliable quantitative information. Anyway, only the metalated forms involving the main isoform of human SOD-1 were detected due to the lower sensitivity. Hence, the combination of both methodologies resulted necessary to obtain detailed structural information from the enzyme.

Characterization and expression of superoxide dismutase genes in Chironomus riparius (Diptera, Chironomidae) larvae as a potential biomarker of ecotoxicity

Superoxide dismutase (SOD, EC 1.15.1.1) is an enzyme involved in the scavenging of reactive oxygen species (ROS) into molecular oxygen and hydrogen peroxide. In this study, a copper-zinc superoxide dismutase (Cu-ZnSOD) gene and a manganese superoxide dismutase (MnSOD) gene in aquatic midge, Chironomus riparius (CrSODs) was identified using an Expressed Sequence Tag (EST) database generated by 454 pyrosequencing. A multiple sequence alignment of C. riparius sequences revealed high homology with other insect sequences in terms of the amino acid level. Phylogenetic analysis of the CrSODs revealed that they were grouped with SODs of other organisms, such as Polypedilum vanderplanki, Drosophila melanogaster, Aedes aegypti, Anopheles gambiae, Culex quinquefasciatus and Bombyx mori. Expression of the corresponding CrSODs was analyzed during different developmental stages and following exposure to various environmental contaminants with different mode of actions i.e., paraquat, cadmium, benzo[a]pyrene, and chloropyrifos. CrSOD gene expression was significantly up or down regulated in response to exposure to the chemicals tested. The overall results suggested that SOD gene expression provided a platform for the understanding of oxidative stress responses caused by exposure to various environmental contaminants, and the SOD genes could be used as biomarkers for environmental disturbances such as oxidative stress initiated by xenobiotics.

A manganese superoxide dismutase (MnSOD) from Ruditapes philippinarum: comparative structural- and expressional-analysis with copper/zinc superoxide dismutase (Cu/ZnSOD) and biochemical analysis of its antioxidant activities

Superoxide dismutases (SODs), antioxidant metalloenzymes, represent the first line of defense in biological systems against oxidative stress caused by excessive reactive oxygen species (ROS), in particular O(2)(•-). Two distinct members of SOD family were identified from Manila clam Ruditapes philippinarum (abbreviated as RpMnSOD and RpCu/ZnSOD). The structural analysis revealed all common characteristics of SOD family in both RpSODs from primary to tertiary levels, including three MnSOD signatures and two Cu/ZnSOD signatures as well as invariant Mn(2+)- and Cu/Zn(2+)-binding sites in RpMnSOD and RpCu/ZnSOD, respectively. Putative RpMnSOD and RpCu/ZnSOD proteins were predicted to be localized in mitochondrial matrix and cytosol, respectively. They shared 65.2% and 63.9% of identity with human MnSOD and Cu/ZnSOD, respectively. Phylogentic evidences indicated the emergence of RpSODs within molluscan monophyletic clade. The analogous spatial expression profiles of RpSODs demonstrated their higher mRNA levels in hemocytes and gills. The experimental challenges with poly I:C, lipopolysaccharide and Vibrio tapetis illustrated the time-dependent dynamic expression of RpSODs in hemocytes and gills. The recombinant RpMnSOD was expressed in a prokaryotic system and its antioxidant property was studied. The rRpMnSOD exhibited its optimum activity at 20 °C, under alkaline condition (pH 9) with a specific activity of 3299 U mg(-1). These outcomes suggested that RpSODs were constitutively expressing inducible proteins that might play crucial role(s) in innate immunity of Manila clam.