Melatonin Alleviates Abscisic Acid Deficiency Inhibition on Photosynthesis and Antioxidant Systems in Rice under Salt Stress

Melatonin and abscisic acid,as major plant hormones,play important roles in the physiological and biochemical activities of crops,but the interaction between the two under salt stress is not yet clear.This study investigated the endogenous levels of melatonin and abscisic acid in rice by using exogenous melatonin,abscisic acid,and their synthetic inhibitors,and examined their interactions under salt stress.The research results indicate that melatonin and abscisic acid can improve rice salt tolerance.Melatonin alleviated the salt sensitivity caused by abscisic acid deficiency,increased antioxidant enzyme activity and antioxidant content in rice treated with abscisic acid synth-esis inhibitors,and reduced total reactive oxygen species content and thiobarbituric acid reactive substance accu-mulation.Melatonin also increased the activity of key photosynthetic enzymes and the content of photosynthetic pigments,maintaining the parameters of photosynthetic gas exchange and chlorophyllfluorescence.In summary,melatonin alleviated the effects of abscisic acid deficiency on photosynthesis and antioxidant systems in rice and improved salt tolerance.This study is beneficial for expanding the understanding of melatonin regulation of crop salt tolerance.

Application of Polygonum minus Extract in Enhancing Drought Tolerance in Maize by Regulating Osmotic and Antioxidant System

Drought stress is a major factor affecting plant growth and crop yield production.Plant extracts as natural biostimulants hold great potential to strengthen plants to overcome drought impacts.To explore the effect of Polygonum minus extract(PME)in enhancing drought tolerance in plants,a study was set up in a glasshouse environment using 10 different treatment combinations.PME foliar application were designed in CRD and effects were closely observed related to the growth,physiology,and antioxidant system changes in maize(Zea mays L.)under well-watered and drought conditions.The seaweed extract(SWE)was used as a comparison.Plants subjected to drought stress exhibited a significant reduction in fresh weight,dry weight,relative water content(RWC),and soluble sugar,but they stimulated the phenolic,flavonoid,proline,glutathione(GSH),malondialdehyde(MDA)and antioxidant enzyme(catalase,CAT;peroxidase,POD;superoxide dismutase,SOD)activities.Foliar application of PME improved fresh and dry weight(FW:33.1%~41.4%;DW:48.0%~43.1%),chlorophyll content(Chl b:87.9%~100.76%),soluble sugar(23.6%~49.3%),and soluble protein(48.6%~56.9%)as well as antioxidant enzyme activities(CAT and POD)compared to CK under drought conditions.while decreasing the level of MDA.Notably,the mitigating effect of PME application with high concentration was more effective than those of SWE.Our study reveals that PME could alleviate drought stress by regulating osmoprotectant content and antioxidant defense system and can be used as an economical and environmentally friendly biostimulants for promoting maize growth under drought stress.

Ellagic Acid Enhances Antioxidant System Activity and Maintains the Quality of Strawberry Fruit during Storage

Ellagic acid(EA)is a natural antioxidant,widely present in a lot of forms’soft fruits,nuts,and other plant tissues,and helpful for promoting human health;however,its protective effect on postharvest fruit and improving the quality index of postharvest fruit have rarely been studied.In this experiment,the strawberries were soaked in 0,100,200,300,400,and 500 mg L^(−1) EA,respectively,and the influential EA on fruit quality and the antioxidant system of strawberries were studied.Compared with the control,EA treatment can reduce the browning degree and rotting rate of strawberry fruit during storage and augment the soluble solid content(SSC).EA treatment can also increase the content of related stuff and enzyme activity in antioxidant systems;the gene expression level of polyphenol oxidase(PPO)in strawberries treated with EA was always down-regulated,correspondingly,the expression of other antioxidant enzyme genes was enhanced.Among the strawberry fruits treated with EA of different concentrations,300 mg L^(−1) EA had the best effect in the process of strawberry preservation.The results suggested that the proper concentration of exogenous EA at 300 mg L−1 could maintain strawberries’quality and enhance the antioxidant system by improving the activities of antioxidative enzymes and the ascorbateglutathione(AsA-GSH)cycle during storage.

Effects of Manganese on the Antioxidant System and Related Gene Expression Levels in the “Hong Yang” Kiwifruit Seedlings

To explore how manganese affects the antioxidant system and the expression levels of related genes of“Hong yang”seedlings,the leaves of its tissue cultured seedlings were taken as test materials,and single factor treatment was performed by changing the manganese chloride(MnCl_(2)·4H_(2)O)solution concentration when spraying the leaves.The expression levels of Mn-SOD,POD64 and POD27 genes in leaves were quantitatively analyzed by real-time quantitative PCR(qRT-PCR)at different determination times.Meanwhile,the contents of malondial-dehyde(MDA),hydrogen peroxide(H_(2)O_(2)),the activities of antioxidant enzymes,including catalase(CAT),peroxidase(POD),and superoxide dismutase(SOD).The results showed that the SOD,CAT,POD,ascorbate peroxidase(APX),and reduced glutathione(GSH)activities in leaves were the highest at 12 h post-treatment with 50μM MnCl_(2)·4H_(2)O.Furthermore,the contents of MDA and H_(2)O_(2) in leaves also peaked when the concentration of H_(2)O_(2) is 50μM,which is the minimum value.Additionally at 50μM Mn^(2+),the Mn-SOD and POD27 expression was up-regulated as compared to the control,which promoted the expression of their respective enzyme activities.However,POD64 expression increased with the increasing Mn^(2+) concentration.Therefore,50μM is the optimal concentration of Mn when exogenously applied on“Hong yang”,which improve the antioxidant enzyme activity and regulate the plant’s physiological and biochemical functions.

Transcriptomes of Litopenaeus vannamei reveal modulation of antioxidant system induced by dietary archaeal carotenoids

Oxidative stress induced by factors such as ammonia nitrogen has become a major issue in shrimp farming.The effects of carotenoids on the growth and antioxidant capability of Litopenaeus vannamei juveniles were investigated in this study using dietary archaeal carotenoids supplementation.For four weeks,shrimp were given diets containing 0 mg/kg(Ctrl)and 55.98 mg/kg(Car)archaeal carotenoids.Dietary archaeal carotenoids significantly enhanced the astaxanthin content in shrimp muscles and carapaces,as well as the superoxide dismutase(SOD)and glutathione peroxidase(GSH-Px)activity(P<0.05).The malonaldehyde(MDA)content in Car group significantly decreased(P<0.05).The transcriptome analysis was conducted to determine the molecular processes in response to archaeal carotenoids supplementation.A total of 1536 differentially expressed genes(DEGs)were detected,including 538 upregulated DEGs and 998 downregulated DEGs.GO functional enrichment analysis between Ctrl and Car indicated that 26 GO terms including extracellular region,metabolic process,and proteolysis were enriched.The KEGG pathway enrichment analysis revealed that the amino sugar and nucleotide sugar metabolism,cysteine and methionine metabolism,glycine serine and threonine metabolism,and amino acid biosynthesis were enriched.Archaeal carotenoids influenced the expression of several important genes involved in reactive oxygen species(ROS)generation,Nrf2 signaling,and antioxidant enzymes.Seven DEGs were chosen to confirm the RNA-Seq data using qRT-PCR.The genes and pathways discovered in this work assist to elucidate the molecular processes through which archaeal carotenoid enhances L.vannamei antioxidative system.

Effect of Soil Drought Stress on Leaf Water Status, Membrane Permeability and Enzymatic Antioxidant System of Maize

A simulation experiment on the responses of maize (Zea mays L.) from the third leaf stage to maturity for different soil water levels (well-watered, moderately stressed, and severely stressed) was conducted by controlling irrigation and using a mobile rain shelter in a neutral loam, meadow soil to determine the effects on leaf water status, membrane permeability and enzymatic antioxidant system for different growth stages. The results indicated that drought stress relied on drought intensity and duration, with more severe drought stress creating more serious effects on maize. Compared with well-watered conditions, during the silking and blister stages moderate stress did not significantly change the relative water content (RWC) and did change significantly the relative conductivity (RC) (P < 0.05) of the leaves; however, severe stress did significantly decrease (P < 0.01) the leaf RWC and increase (P < 0.01) membrane permeability (leaf relative conductivity). Furthermore, under severe drought stress antioxidant enzyme activities declined significantly (P < 0.01) in later stages, namely for superoxide dismutase (SOD) the tasseling and blister stages, for peroxidase (POD) the milk stage, and for catalase (CAT) during the tasseling, blister, and milk stages. Meanwhile, membrane lipid peroxidation (measured as malondialdehyde content) significantly increased (P < 0.01) in all stages.

Four-Octyl itaconate ameliorates periodontal destruction via Nrf2-dependent antioxidant system

Periodontitis is a widespread oral disease characterized by continuous inflammation of the periodontal tissue and an irreversible alveolar bone loss, which eventually leads to tooth loss. Four-octyl itaconate(4-OI) is a cell-permeable itaconate derivative and has been recognized as a promising therapeutic target for the treatment of inflammatory diseases. Here, we explored, for the first time,the protective effect of 4-OI on inhibiting periodontal destruction, ameliorating local inflammation, and the underlying mechanism in periodontitis. Here we showed that 4-OI treatment ameliorates inflammation induced by lipopolysaccharide in the periodontal microenvironment. 4-OI can also significantly alleviate inflammation and alveolar bone loss via Nrf2 activation as observed on samples from experimental periodontitis in the C57BL/6 mice. This was further confirmed as silencing Nrf2 blocked the antioxidant effect of 4-OI by downregulating the expression of downstream antioxidant enzymes. Additionally, molecular docking simulation indicated the possible mechanism under Nrf2 activation. Also, in Nrf2-/-mice, 4-OI treatment did not protect against alveolar bone dysfunction due to induced periodontitis, which underlined the importance of the Nrf2 in 4-OI mediated periodontitis treatment.Our results indicated that 4-OI attenuates inflammation and oxidative stress via disassociation of KEAP1-Nrf2 and activation of Nrf2 signaling cascade. Taken together, local administration of 4-OI offers clinical potential to inhibit periodontal destruction,ameliorate local inflammation for more predictable periodontitis.

The role of antioxidant system in freezing acclimation-induced freezing resistance of Populus suaveolens cuttings

We investigated the changes in the contents of H202, malonaldehyde （MDA） and endogenous antioxidants, the activities of protective enzymes and some critical enzymes involved in the ascorbate-glutathione （ASA-GSH） cycle as well as freezing resistance （expressed as LT50） and correlations mentioned above, in detail using Populus suaveolens cuttings. The purpose was to explore the physiological mechanism of the enhancement of freezing resistance induced by freezing acclimation at -20℃, and to elucidate the physiological mechanisms by which trees adapt to freezing. The results showed that freezing acclimation enhanced the activities of superoxide dismutase （SOD）, peroxidase （POD）, catalase （CAT）, monodehydroascorbate reductase （MDAR）, ascorbate peroxidase （APX）, dehydroascorbate reductase （DHAR） and glutathione reductase （GR）. And it increased the contents of reduced ascorbate （ASA）, reduced glutathione （GSH）, dehydroascorbate （DHA） and oxidized glutathione （GSSG）. However, H202 and MDA contents and LT50 of cuttings were decreased. LTs0 in cuttings was found to be closely correlated to the levels of SOD, POD, CAT, APX, DHAR, MDAR, GR, H202, MDA, ASA, GSH, DHA and GSSG during freezing acclimation. This suggested that the enhancement of freezing resistance of cuttings induced by freezing acclimation may relate to the distinct increase for the levels of SOD, POD, CAT, APX, DHAR, MDAR, GR, ASA, GSH, DHA, and GSSG. In addition, the observed levels of APX, DHAR, MDAR, GR, ASA, DHA, GSH and GSSG were higher than those of SOD, POD and CAT during freezing acclimation. It indicated that a higher capacity of the ASA-GSH cycle is required for H202 detoxification, and growth and development of cuttings. Based on the obtained results, it can be concluded that the ASA-GSH cycle plays an important role in enhancement of freezing resistance of P. suaveolens cuttings during freezing acclimation.

Antioxidant system responses in two co-occurring green-tide algae under stress conditions

Green tides have occurred every year from 2007 to 2014 in the Yellow Sea. Ulva prolifera （Mtiller） J. Agardh has been identified as the bloom-forming alga, co-occurring with U. intestinalis. We observed distinct strategies for both algal species during green tides. U.prolifera exhibited a high abundance initially and then decreased dramatically, while U. intestinalis persisted throughout. The antioxidant system responses of these two macroalgae were compared in the late phase of a green tide （in-situ） and after laboratory acclimation. Lipid peroxidation and antioxidant system responses differed significantly between the two. Malondialdehyde and hydrogen peroxide contents increased significantly in-situ in U. prolifera, but not in U. intestinalis. In U. prolifera, we observed a significant decrease in total antioxidant ability （T-AOC）, antioxidant enzymes （SOD and Apx）, and non-enzyme antioxidants （GSH and AsA） in-situ. U. intestinalis showed the same pattern of T-AOC and SOD, but its Gpx, Apx, and GSH responses did not differ significantly. The results suggest that U. prolifera was more susceptible than U. intestinalis to the harsh environmental changes during the late phase of a Yellow Sea green tide. The boom and bust strategy exhibited by U. prolifera and the persistence of U. intestinalis can be explained by differences in enzyme activity and antioxidant systems.

Antioxidant System of the Intertidal Mollusk Littorina kurila in Its Natural Habitat

Based on the theory of oxidative stress, it is believed that the induction of antioxidant components of the cellular defense system reflects the adaptive compensatory response of an organism aimed at overcoming stressful conditions. Therefore, this work concentrated on investigating the effect of the low and high tides on the antioxidant system of L. （Littorina） kurila and also compared the antioxidant parameters of two species of gastropods： intertidal--L, kurila and subtidal--L, squalida. The following parameters were evaluated in the hepatopancreas of mollusks： the activity of the antioxidant enzymes SOD （superoxide dismutase）, CAT （catalase）, and GR （glutathione reductase）, the production of ROS （reactive oxygen species）, and the levels of GSH （glutathione） and the lipid peroxidation product-MDA （malondialdehyde）. The results of this work indicate that the state of the antioxidant system of L. kurila reflected the adaptive capacity of the species in the changing environmental conditions.

Effects of Hydrogen on Storage Decay and Antioxidant System of Strawberry

In order to determine whether hydrogen acts as antioxidant in plant tissues,fresh strawberry was put in sealed bags filled with 4%H_(2) atmosphere(T_(1)),100%H_(2)(T_(2)),100%air(CK_(1))and 100%N_(2)(CK_(2)),respectively.The decay rate,soluble solids content(SSC),titration acid(TA),ascorbic acid(Vc),MDA content,SOD and antioxidant activity in strawberry were measured during storage periods.Results showed that the decay rate and MDA content were reduced in H_(2) treatments;and H_(2) treatments gave lower level of TA and higher SSC,Vc,SOD and antioxidant activity,and 100%H_(2) had the best effect.It is suggested that strawberry fruit quality,antioxidant system and membrane lipid peroxidation were affected by H_(2) treatments.

Effects of Drought Stress on Antioxidant System of Leaves from Different Citrus Rootstocks

[Objective] The paper aims to study the effects of drought stress on antioxidation system of different Citrus rootstock leaves. [Method] Potted plant experiments were carried out to control the water content of soil in pots,in order to investigate the effects of drought stress on antioxidation system activity （SOD,POD and CAT） and the content of protein,GSH,MDA and O-·2 from the leaves of Shandong Zhike,Ningminju,Yangshuojinbaosuanju,Huapijinju and Guizhi No.1. [Result] The content of chlorophyll a,chlorophyll b and chlorophyll （a＋b） from the test 5 breeds decreased with the enhancement of drought stress,and there were significant differences between them and the control under the severe stress; the activities of SOD,POD and CAT from the 5 breeds increased as the drought stress strengthened; the content of soluble protein declined while that of GSH,MDA and O-·2 rose because of the drought stress. [Conclusion] This research provided a good reference to choose the breeds of citrus rootstocks in arid and semi-arid areas.

Effect of methoxychlor on antioxidant system of goat epididymal sperm in vitro

Aim: To evaluate the effect of methoxychlor on the antioxidant system of goat epididymal sperm. Methods:Epididymis of adult goat was obtained from local slaughter houses and sperm were collected by chopping the epididymisin modified Ringer's phosphate solution (RPS). After several washings, the sperm samples were dispersed in RPS andincubated with methoxychlor (1μmol/L, 10μmol/L and 100μmol/L) and methoxychlor + vitamin C (100μmol/Leach) for 3 h at 32℃. After incubation, the sperm motility and viability were assessed. An aliquot of sperm samplewas homogenized, centrifuged and used for the assay of superoxide dismutase, glutathione peroxidase, glutathione re-ductase and lipid peroxidation. Results; In methoxychlor-incubated sperm and in sperm co-incubated with methoxy-chlor and vitamin C, the sperm motility and viability showed no significant changes as compared to the correspondingcontrols. In methoxychlor-incubated sperm the activity of superoxide dismutase, glutathione reductase and glutathioneperoxidase were decreased while lipid peroxidation was increased in a dose-dependent manner. Co-incubation of spermwith methoxychlor and vitamin C showed no changes in the activity of superoxide dismutase, glutathione reductase andglutathione peroxidase and in the level of lipid peroxidation. Conclusion; Methoxychlor induced oxidative stress inepididymal sperm of goats by decreasing the levels of antioxidant enzymes. Co-incubation of sperm with methoxychlorand vitamin C, a natural antioxidant, reversed the effect of methoxychlor. (Asian J Androl 2001 Dec; 3; 285 - 288)

Free radicals and antioxidant systems in reflux esophagitis and Barrett's esophagus

AIM: Experimental studies suggest that free radicals are involved in acid and pepsin-induced damage of esophageal mucosa. The profile and balance between free radicals and antioxidant systems in human esophagitis are unknown. METHODS: Superoxide anion and its powerful oxidant reaction with nitric oxide (peroxynitrite) generation were determined in esophageal mucosal biopsies from 101 patients with different gastro-esophageal reflux diseases and 28 controls. Activity of both superoxide dismutase (SOD) and catalase, and reduced glutathione (GSH) levels, were also assessed. Expression of Cu,ZnSOD, MnSOD and tyrosine-nitrated MnSOD were analyzed by Western blot and/or immunohistochemistry. RESULTS: The highest levels of superoxide anion generation were found in patients with severe lesions of esophagitis. Peroxynitrite generation was intense in Barrett's biopsies, weaker in esophagitis and absent/weak in normal mucosa. Expression of Cu,ZnSOD and MnSOD isoforms were present in normal mucosa and increased according to the severity of the lesion, reaching the highest level in Barrett's esophagus. However, SOD mucosal activity significantly decreased in patients with esophagitis and Barrett's esophagus, which was, at least in part, due to nitration of its tyrosine residues. Catalase activity and GSH levels were significantly increased in mucosal specimens from patients with esophagitis and/or Barrett's esophagus. CONCLUSION: A decrease in SOD antioxidant activity leading to increased mucosal levels of superoxide anion and peroxynitrite radicals may contribute to the development of esophageal damage and Barrett's esophagus in patients with gastroesophageal reflux. Administration of SOD may be a therapeutic target in the treatment of patients with esophagitis and Barrett's esophagus.

Effect of lindane on testicular antioxidant system and steroidogenic enzymes in adult rats

Aim: To find out the effect of lindane on testicular antioxidant system and testicular steroidogenesis in adult malerats. Methods: Adult male rats were orally administered with lindane at a dose of 5.0 mg/kg body weight per dayfor 30 days. Twenty-four hours after the last treatment the rats were killed using anesthetic ether. Testes, epididymis,seminal vesicles and ventral prostate were removed and weighed. A 10% testicular homogenate was prepared and cen-trifuged at 4℃. The supernatant was used for various biochemical estimations. Results; The body weight and theweights of testes, epididymis, seminal vesicles and ventral prostate were reduced in lindane-treated rats. There was asignificant decline in the activities of antioxidant enzymes superoxide dismutase (SOD), catalase and glutathione reduc-tase while an increase in hydrogen peroxide (H_2O_2) generation was observed. The specific activities of testicularsteroidogenic enzymes 3β-hydroxysteroid dehydrogenase and 17β-hydroxysteroid dehydrogenase were decreased. Thelevels of DNA, RNA and protein were also decreased in lindane-treated rats. Conclusion: Lindane induces oxida-tive stress and decreases antioxidant enzymes in adult male rats.

Responses of the antioxidant system to fluroxypyr in foxtail millet (Setaria italica L.) at the seedling stage

Foxtail millet （Setaria italica L.） is an important food and fodder crop in semi-arid areas. However, there are few herbicides suitable for use on weed control in field-grown foxtail millet during the post-emergence herbicides stage. The present study was conducted using four concentrations （0.5, 1, 2, and 4 L ai ha-1） of foliar-applied fluroxypyr, and the effect of fluroxypyr on selected metabolic and stress-related parameters in foxtail millet were assessed after 15 days. In this study, increasing concentrations decreased plant height and accumulation of chlorophylls. Our results also showed that malondialdehyde （MDA） accumulated in response to fluroxypyr application, demonstrating increased lipid peroxidation due to excessive reactive oxygen species production. In response to this oxidative stress, the activities of antioxidant enzymes were generally enhanced. Non-enzymatic antioxidant defense systems, which function in concert with antioxidant enzymes, can also protect plant cells from oxidative damage by scavenging reactive oxygen species （ROS）. In conclusion, the hybrid variety （Zhangzagu） exhibited a greater tolerance to fluroxypyr than did the conventional variety Jingu 21, which might be associated with the antioxidant mechanisms of Zhangzagu hybrid millet.

Effects of 24-Epibrassinolide on Antioxidant System in Cucumber Seedling Roots Under Hypoxia Stress

This article aims to study the effects of exogenous 24-epibrassinolide （EBR） on the changes in ROS, activities of antioxidative enzymes and antioxidants in cucumber （Cucumis sativus L.） seedling roots under hypoxia stress. Seedlings of a hypoxiaresistant cultivar, Lühachun 4, and a hypoxia-sensitive cultivar, Zhongnong 8, were hydroponically grown for 8 d in normoxic or hypoxic nutrient solutions that were added or not added with 10^-3 mg L^-1 EBR. Under hypoxia stress, the ROS levels and the lipid peroxidation were significantly increased in the roots upon exposure to hypoxia stress, which were inhibited by EBR application. The EBR treatment significantly increased the seedlings growth and SOD, APX, GR activities, and contents of AsA and GSH under hypoxia stress. From the results obtained in this study, it can be concluded that oxidative damage on seedling roots by hypoxia stress can be considerably alleviated and the tolerance of plants was elevated.

Impact of poly chlorinated biphenyl (Aroclor 1254) and vitamin C on antioxidant system of rat ventral prostate

Aim: To evaluate the effect of polychlorinated biphenyls (PCB) and vitamin C on ventral prostatic antioxidant system in adult male rats. Methods: A group of 20 adult male rats were administered ip Aroclor 1254 in corn oil at a dose of 2 mg·kg-1·day-1 for 30 days. Ten control rats were administered only the vehicle. After 30 days the treated rats were divided at random into 2 sub-groups of 10 animals each. One sub-group received vitamin C at a dose of 500 mg·kg-1·day-1 for 10 days. The other group was maintained as Aroclor 1254 control. Twenty-four hours after the last treatment the rats were killed by decapitation. Ventral prostatic homogenate was prepared and used for the estimation of enzymatic antioxidants, including superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST) and hydrogen peroxide (H2O2), lipid peroxidation (LPO) and prostatic acid phosphatase. The serum levels of total T3, total T4, TSH, testosterone and estradiol were also assayed. Results: The body weight and ventral prostatic weight were reduced in PCB treated rats. The activities of SOD, CAT, GST and acid phosphatase were decreased while the levels of H2O2 and lipid peroxidation were increased in the ventral prostate of PCB treated rats. Administration of vitamin C restored these parameters. Serum levels of thyroid hormones, estradiol and testosterone were decreased in PCB treated animals. Administration of vitamin C restored the thyroid hormone levels. Conclusion: PCB induces oxidative stress and decreases the antioxidant enzymes in the ventral prostate of adult male rats; the effects could be reversed by the administration of vitamin C.

Effects of Mercuric Chloride on Antioxidant System and DNA Integrity of the Crab Charybdis japonica

Mercury （Hg） is one of the commonly encountered heavy metals, which is widespread in inshore sediments of China. In order to investigate the toxicity of Hg on marine invertebrates, we studied the effects of the divalent mercuricion （Hg2＋） （at two final concentrations of 0.0025 and 0.0050mgL-1, prepared with HgC12） on metallothionein （MT） content, DNA integrity （DNA strand breaks） and catalase （CAT） in the gills and hepatopancreas, antioxidant enzyme activities of superoxide dismutase （SOD）, catalase （CAT） and glutathione peroxidase （GPx）, in the hemolymph, gills and hepatopancreas of the portunid crab Chao,bdisjaponica for an experiment period up to 15 d. The results indicated that MT was significantly induced after 3 d, with a positive correlation with Hg2＋ dose and time in the hepatopancreas and a negative correlation with Hg2＋ dose and time in the gills. While CAT in the hemolymph was not detected, it increased in the hepatopancreas during the entire experiment; SOD and GPx in the three tissues were stimulated after 12h, both attained peak value and then reduced during the experimental period. Meanwhile, DNA strand breaks were all induced significantly after 12 h. These results suggested the detoxification strategies against Hg2＋ in three tissues of C. japonica.

Enzymatic antioxidant system in vascular inflammation and coronary artery disease

In biological systems there is a balance between the production and neutralization of reactive oxygen species(ROS). This balance is maintained by the presence of natural antioxidants and antioxidant enzymes suchas superoxide dismutase(SOD), catalase and glutathione peroxidase. The enhancement of lipid peroxidation or the decrease of antioxidant protection present in metabolic diseases or bad lifestyle can induce endothelial dysfunction and atherosclerosis.Clinical studies have shown that oxidative stress can increase ROS reducing the formation of antioxidant defences, especially in subjects with coronary artery disease(CAD). Some observation indicated that in the early stages of the disease there is a homeostatic upregulation of the antioxidant enzyme system in response to increased free radicals to prevent vascular damage.As soon as free radicals get to chronically elevated levels, this compensation ceases. Therefore, SOD and the other enzymes may represent a good therapeutic target against ROS, but they are not useful markers for the diagnosis of CAD. In conclusion antioxidant enzymes are reduced in presence of metabolic disease and CAD. However the existence of genes that promote their enzymatic activity could contribute to create new drugs for the treatment of damage caused by metabolic diseases or lifestyle that increases the plasma ROS levels.