Induction in the antioxidative systems and lipid peroxidation in suspension culture roots of Panax ginseng induced by oxygen in bioreactors

Roots of mountain ginseng (Panax ginseng) were exposed to various levels of oxygen (O₂) (30, 40 and 50%) for 15, 30 and 45 days in 5 L (working volume 4 L) airlift bioreactors. Ginsenoside accumulation and dry weight was enhanced up to 40% O₂; but thereafter declined ginsenoside and dry weight of the roots by increasing level of O₂. Gradual increase in H₂O₂ content and lipoxygenase activity (LOX), resulting in cellular damage and oxidative stress as indicated by increased malondialdehyde (MDA) content after 30 and 45 days at all O₂ levels was shown. Increased levels of O₂ (above ambient) resulted in increases in non-protein thiol (NP-SH) and cysteine content. Higher activities of ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), glutathione reductase (GR), catalase (CAT), guaiacol peroxidase (G-POD), superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione S transferase (GST) activities indicated that antioxidant enzymes played an important role in protecting the roots from O₂ up to 45 days, except at 50% O₂ where GR, GST and GPx decreased compared to the control. However, after 45 days, SOD activity decreased significantly compared to the control in the O₂-treated roots. This reflects the sensitivity of enzymes to O₂ toxicity. In stress related experiment, roots showed increased synthesis of ginsenosides when 25 and 50 μM H₂O₂ was applied. However, higher dose and increasing treatment inhibited ginsenoside synthesis. The results indicate that plant roots could grow and protect themselves from O₂ stress by coordinated induction of various antioxidant enzymes and metabolite contents. These results suggest that O₂ supplementation is useful for ginsenoside accumulation using 5-L bioreactors.     

Differential expression and anti-oxidant function of glutathione peroxidase 3 in mouse uterus during decidualization

Glutathione peroxidase 3 (GPX3) is an important member of antioxidant enzymes for reducing reactive oxygen species and maintaining the oxygen balance. Gpx3 mRNA is strongly expressed in decidual cells from days 5 to 8 of pregnancy. After pregnant mice are treated with GPX inhibitor for 3 days, pregnancy rate is significantly reduced. Progesterone stimulates Gpx3 expression through PR/HIF1α in mouse endometrial stromal cells. In the decidua, the high level of GPX3 expression is closely associated with the reduction of hydrogen peroxide (H₂O₂). Based on our data, GPX3 may play a major role in reducing H₂O₂ during decidualization.     

Antioxidant response of a novel Streptomyces sp. M3004 isolated from legume rhizosphere to H2O2 and paraquat

This paper aims to investigate the effect of H₂O₂ and paraquat on the activities of superoxide dismutase (SOD) and catalase (CAT), and membrane lipid peroxidation (LPO) levels in newly isolated Streptomyces sp. M3004. SOD activities of Streptomyces sp. M3004, grown in 10 mM and 30 mM H₂O₂, were significantly lower than the control cultures. On the other hand, as an antioxidant enzyme, CAT activity in both H₂O₂ treatment conditions increased significantly compared with the control. These activity values in 10 mM and 30 mM H₂O₂ treatment on the 48th hour of incubation were 3.8- and 6.6-fold higher than the control, respectively. SOD activity decreased significantly with respect to paraquat concentration, which was added at the start of the incubation. CAT activities increased significantly in 1.0 mM and 3.0 mM paraquat treatments compared to control. As an indicative marker of membrane damage, LPO levels of the novel isolate Streptomyces sp. M3004 treated with H₂O₂, and paraquat stress conditions were significantly higher than the control. Nevertheless, compared with the 30 mM H₂O₂ in both treatment conditions, LPO levels in 10 mM H₂O₂ were significantly higher. The decreases in SOD activities in paraquat and H₂O₂ treatment conditions resulted in the increases in the LPO levels although it increases in CAT activities.     

Antioxidant activity and protection of human umbilical vein endothelial cells from hydrogen peroxide-induced injury by DMC,a chalcone from buds of Cleistocalyx operculatus

The aim of this work was to study the antioxidant activity and the protective effect of 2′,4′-dihydroxy-6′-methoxy-3′,5′-dimethylchalcone (DMC), the main compound from the buds of Cleistocalyx operculatus, on human umbilical vein endothelial cells against cytotoxicity induced by H₂O₂. The antioxidant activities of DMC were measured by ABTS assay, ferric reducing antioxidant power (FRAP) and hydroxyl radical scavenging activity, and protective effects of DMC on human umbilical vein endothelial cells against cytotoxicity induced by H₂O₂ were tested. DMC was found to have high ABTS radical scavenging activity (176.5 ± 5.2 μmol trolox equivalents/500 μmol DMC) and strong ferric reducing antioxidant power (213.3 ± 5.8 μmol trolox equivalents/500 μmol DMC). In addition, DMC scavenged the hydroxyl radicals, with IC₅₀ values of 243.7 ± 6.3 μM, slightly lower than the reference antioxidant ascorbic acid (ASC). Moreover, DMC could protect the human umbilical vein endothelial cells against H₂O₂-induced cytotoxicity by decrease intracellular and extracellular ROS levels, reduction in catalase (CAT) activity and increment in malondialdehyde (MDA) level. These results suggested that DMC has the potential to be used in the therapy of oxidative damage.     

Induction of heme oxygenase-1 by chamomile protects murine macrophages against oxidative stress

AimsProtection of cells from oxidative insult may be possible through direct scavenging of reactive oxygen species, or through stimulation of intracellular antioxidant defense mechanisms by induction of antioxidant gene expression. In this study we investigated the cytoprotective effect of chamomile and elucidated the underlying mechanisms.Main methodsThe cytoprotective effect of chamomile was examined on H₂O₂-induced cellular stress in RAW 264.7 murine macrophages.Key findingsRAW 264.7 murine macrophages treated with chamomile were protected from cell death caused by H₂O₂. Treatment with 50 μM H₂O₂ for 6 h caused significant increase in cellular stress accompanied by cell death in RAW 264.7 macrophages. Pretreatment with chamomile at 10–20 μg/mL for 16 h followed by H₂O₂ treatment protected the macrophages against cell death. Chamomile exposure significantly increased the expression of antioxidant enzymes viz. heme oxygenase-1 (HO-1), peroxiredoxin-1 (Prx-1), and thioredoxin-1 (Trx-1) in a dose-dependent manner, compared with their respective controls. Chamomile increased nuclear translocation of Nrf2 with increased phosphorylated Nrf2 levels, and binding to the antioxidant response element in the nucleus.SignificanceThese molecular findings for the first time provide insights into the mechanisms underlying the induction of phase 2 enzymes through the Keap1-Nrf2 signaling pathway by chamomile, and provide evidence that chamomile possesses antioxidant and cytoprotective properties.     

Protective effects of aloe-emodin on scopolamine-induced memory impairment in mice and H2O2-induced cytotoxicity in PC12 cells

Aloe-emodin (AE) is one of the most important active components of Rheum officinale Baill. The present study aimed to investigate that AE could attenuate scopolamine-induced cognitive deficits via inhibiting acetylcholinesterase (AChE) activity and modulating oxidative stress. Kunming (KM) mice were received intraperitoneal injection of scopolamine (2 mg/kg) to induce cognitive impairment. Learning and memory performance were assessed in the Morris water maze (MWM). After behavioral testing, the mice were sacrificed and their hippocampi were removed for biochemical assays (superoxide dismutase (SOD), glutathione peroxidase (GPx), malondialdehyde (MDA), AChE and acetylcholine (ACh)). In vitro, we also performed the AChE activity assay and H₂O₂-induced PC12 cells toxicity assay. After 2 h exposure to 200 μM H₂O₂ in PC12 cells, the cytotoxicity were evaluated by cell viability (MTT), nitric oxide (NO)/lactate dehydrogenase (LDH) release and intracellular reactive oxygen species (ROS) production. Our results confirmed that AE showed significant improvement in cognitive deficit in scopolamine-induced amnesia animal model. Besides, it increased SOD, GPx activities and ACh content, while decreased the level of MDA and AChE activity in AE treated mice. In addition, AE was found to inhibit AChE activity (IC₅₀ = 18.37 μg/ml) in a dose-dependent manner. Furthermore, preincubation of PC12 cells with AE could prevent cytotoxicity induced by H₂O₂ and reduce significantly extracellular release of NO, LDH and intracellular accumulation of ROS. The study indicated that AE could have neuroprotective effects against Alzheimer’s disease (AD) via inhibiting the activity of AChE and modulating oxidative stress.     

Effect of the dietary probiotic Clostridium butyricum on growth,intestine antioxidant capacity and resistance to high temperature stress in kuruma shrimp Marsupenaeus japonicus

A 56-day feeding trial followed by an acute high temperature stress test were performed to evaluate the effect of dietary probiotic Clostridium butyricum (CB) on growth performance and intestine antioxidant capacity of kuruma shrimp Marsupenaeus japonicus. Shrimp were randomly allocated in 9 tanks (30 shrimp per tank) and triplicate tanks were fed with diets containing different levels of C. butyricum (1×10⁹ cfu/g): 0 mg g⁻¹ feed (Control), 100 mg g⁻¹ feed (CB-100), 200 mg g⁻¹ feed (CB-200) as treatment groups. The results indicated that dietary supplementation of C. butyricum increased the growth performance and decreased the feed conversion rate (FCR) of shrimp in the CB-100 group. HE stain showed that C. butyricum increased the intestine epithelium height of M. japonicus. C. butyricum supplemented in diets decreased·O₂^- generation capacity and malondialdehyde (MDA) content, and increased total antioxidant capacity (T-AOC), catalase (CAT) and peroxidase (POD) activity and the expression level of heat shock protein 70 (hsp70) and metallothionein (mt) gene in intestine of shrimp cultured under normal condition for 56 d, while no significant changes in glutathione peroxidase (GPx) activity and ferritin gene expression level. After shrimp exposed to high temperature stress 48 h, the lower level of·O₂^- generation capacity and MDA content, and the higher level survival, activities of T-AOC, CAT, GPx and POD, as well as hsp70, ferritin and mt gene expression level were found in intestine of two C. butyricum groups. These results revealed that C. butyricum could improve the growth performance, increase intestine antioxidant capacity of M. japonicus against high temperature stress, and could be a potential feed additive in shrimp aquaculture.     

White shrimp Litopenaeus vannamei catalase: Gene structure,expression and activity under hypoxia and reoxygenation

Catalase (EC 1.11.1.6) is an antioxidant enzyme involved in redox equilibrium, regulating hydrogen peroxide (H₂O₂) concentration, a harmful reactive oxygen species (ROS) that is produced during hypoxia. Hypoxia occurs commonly in aquatic environments and in shrimp farms. We studied the catalase gene of the shrimp Litopenaeus vannamei and tested its expression and enzyme activity during hypoxia (1.5 mg/L O₂; 6 and 24 h) and reoxygenation (1 h after hypoxia). The complete gene is 2974 bp long and has four introns of 821, 223, 114 and 298 bp, respectively. The first intron has tree microsatellites, with GT and (T)AT(GT) repeated sequences. L. vannamei catalase is part of an invertebrate clade including crustaceans and rotifers. Catalase expression and activity is different in gills and hepatopancreas. Expression in gills increased 3.2 and 3-fold in response to hypoxia and reoxygenation (6 and 24 h hypoxia, followed by 1 h reoxygenation) compared to normoxia, while no differences were detected in the expression and activity in hepatopancreas. Catalase activity in gills had a contrary response to expression in hypoxia and reoxygenation.     

Photooxidation and antioxidant responses in the earthworm Amynthas gracilis exposed to environmental levels of ultraviolet B radiation

Ultraviolet (UV) radiation leads to photooxidation in various organisms. Our previous study demonstrated that ultraviolet B (UV-B) radiation is lethal for particular species of earthworms, but the mechanisms responsible for the lethality are unclear. In our current study, we investigated that ultraviolet light causes photooxidative damage and reduces antioxidant responses in the earthworm Amynthas gracilis. Intact earthworms and skin/muscle tissue extracts were exposed to UV-B radiation for in vivo and in vitro studies. Both in vitro and in vivo results showed that the products of photooxidative damage, MDA and H₂O₂, increased after UV-B exposure. Glutathione peroxidase (GPx) and catalase were inhibited immediately after exposure to high doses (3000 J/m²) of UV-B radiation in vivo. Catalase activity was increased following a low UV-B dose (500 J/m²) in vivo, but decreased in response to all dosage levels in vitro. These data indicate that a relationship exists between UV-B induced damage and photooxidation and also that catalase and GPx act as important antioxidants to prevent photooxidation. According to these data, A. gracilis exhibits high sensitivity to environmental levels of UV-B. Therefore, A. gracilis represents a sensitive and cost-effective model organism for investigations of UV-radiation damage and environmental UV stress.     

A dissection of the effects of ethylene,H2O2 and high irradiance on antioxidants and several genes associated with stress and senescence in tobacco leaves

Ethylene and hydrogen peroxide are involved in the modulation of stress responses in plants, but their interrelation is not well understood. This work was designed to find differences between the actions of ethylene and H₂O₂ on antioxidants and senescence markers. Leaves of Nicotiana tabacum were sprayed with H₂O₂ or with ethephon (precursor of ethylene). To find the possible modulation of responses to acute abiotic stress, ethephon- and H₂O₂-sprayed leaves were further subjected to high irradiance (HL). The application of H₂O₂ strongly stimulated ethylene synthesis (ACC). Ethylene and H₂O₂, as single factors, stimulated the trolox equivalent antioxidant capacity (TEAC) and the activity of catalase (CAT), in contrast to HL alone (stimulation of nonspecific peroxidases and the total glutathione pool). However, after combined treatments (ethylene + HL and H₂O₂ + HL), the stimulatory action of H₂O₂ was related to TEAC and CAT activity, while the application of ethylene stimulated the total glutathione pool. Hydrogen peroxide enhanced the expression of the three CAT genes (Cat1, Cat2 and Cat3), in contrast to ethylene (Cat2 and Cat3) and HL (Cat1). In regard to the markers of senescence and pathogenesis the most pronounced difference between the actions of ethylene and H₂O₂, as single factors, was related to NPR1, whereas when leaf spraying was combined with HL, differences were found at WRKY53 and PR1a. HL reversed the stimulatory effects of H₂O₂/ethylene-driven enhancements of the expression of several genes (Cat1, Cat2, NPR1, WRKY53). These results show that multiple stressors, as usually encountered by plants in nature, may largely change those expression patterns of genes determined in a single factor analysis. Moreover, the actions of HL (often considered the internal H₂O₂ trigger) and of exogenous H₂O₂ on gene expression are clearly different.     

Impact of Moringa oleifera leaf extract in reducing the effect of lead acetate toxicity in mice

This study aimed to assess the impact of Moringa oleifera (M. oleifera) leaf extract against the poisoning of lead acetate; therefore, sixty mice were allocated into 4 groups with 15 in each, as G1) blank control, G2) supplied with 300 mg/kg body weight (BWT). M. oleifera extract, G3) supplied with 60 mg/kg BWT of lead acetate [Pb(C₂H₃O₂)₂], and G4) supplied with extract of M. oleifera + lead acetate. The liver enzymes were elevated post-treatment with Pb(C₂H₃O₂)₂, which then lowered to almost the normal level when M. oleifera was supplied to mice previously treated with Pb(C₂H₃O₂)₂. The values in (G3) decreased when compared with G1 (92.33 ± 12.99, 21.67 ± 2.91 and 98.00 ± 13.20 U/L, respectively. Also, the cholesterol and low-density lipoprotein levels were elevated post-supplementation with M. oleifera and Pb(C₂H₃O₂)₂. Pb(C₂H₃O₂)₂ improves the lipid profile, whereas M. oleifera pretreatment reduced cholesterol (CHOL), high density low cholesterol (HDL-c), and low-density low cholesterol (LDL-c) levels in animals fed Pb(C₂H₃O₂)₂. Pb(C₂H₃O₂)₂ elevates the total protein but lowers the total bilirubin and triglycerides post M. oleifera treatment and Pb(C₂H₃O₂)₂ when contrasted with G1. The protective effect of M. oleifera was caused by the fact that it lowered triglycerides (TG) and total bilirubin (TBIL) and raised total protein (TP). After administration of Pb(C₂H₃O₂)₂, the histological examination revealed alterations in the hepatocytes and kidneys of G3. Also, the liver and kidney cells in mice supplied with M. oleifera after Pb(C₂H₃O₂)₂ poisoning recovered. In conclusion, Pb is toxic, and the usage of M. oleifera partially enhances the negative impacts induced by Pb(C₂H₃O₂)₂.     

The seed ecology of an ornamental wattle in South Africa — Why has Acacia elata not invaded a greater area?

Australian Acacia species introduced to South Africa as ornamentals have notably smaller invasive ranges than those introduced for forestry or dune stabilization. We asked whether the relatively small invasive extent of Acacia elata, a species used widely for ornamental purposes, is due to low rates of reproduction. Age at reproductive maturity, seed dispersal, annual seed production, seed bank dynamics and seed germination and viability were assessed at five sites in the Western Cape. Results indicate that A. elata has similar traits to other invasive Australia Acacia species: annual seed input into the leaf litter was high (up to 5000 seeds m^− 2); large seed banks develop (> 20,000 seeds m^− 2) in established stands; seed germinability is high (> 90%); seeds accumulate mostly in the top soil layers but can infiltrate to depths of 40 cm; and seed germination appears to be stimulated by fire. However the age at the onset of reproduction (~ 4 years) is longer than most widespread invaders (~ 3 years) and dispersal is fairly limited (seeds fell up to distances of 6 m from the parent canopy; the highest density of seed rain was found directly under the canopy with over 20% of seeds falling directly under the terminal branches). We suggest that the current limited distribution of invasive A. elata populations is the result of the relatively small size of initial populations (cf. large plantations and widespread plantings for forestry and dune stabilization species), the species' apparent lack of secondary dispersal vectors, and the planting of trees in gardens and urban settings offer limited opportunities for recruitment, proliferation and spread. The species is, however, increasing in abundance and range. We propose methods to improve management of invasions of the species. Management to reduce seed production of this species through classical biological control, as has been achieved for other Australian Acacia species in South Africa, should be prioritised.     

Effects of salt stress on ion content,antioxidant enzymes and protein profile in different tissues of Broussonetia papyrifera

Although some plant responses to salinity have been characterized, the precise mechanisms by which salt stress damages plants are still poorly understood especially in woody plants. In the present study, the physiological and biochemical responses of Broussonetia papyrifera, a tree species of the family, Moraceae, to salinity were studied. In vitro-produced plantlets of B. papyrifera were treated with varying levels of NaCl (0, 50, 100 and 150 mM) in hydroponic culture. Changes in ion contents, accumulation of H₂O₂, as well as the activities and isoform profiles of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in the leaves, stems and roots were investigated. Under salt stress, there was higher Na⁺ accumulation in roots than in stems and leaves, and Ca^2 +, Mg^2 + and P^3 + content, as well as K⁺/Na⁺ ratio were affected. NaCl treatment induced an increase in H₂O₂ contents in the tissues of B. papyrifera. The work demonstrated that activities of antioxidant defense enzymes changed in parallel with the increased H₂O₂ and salinity appeared to be associated with differential regulation of distinct SOD and POD isoenzymes. Moreover, SDS-PAGE analysis of total proteins extracted from leaves and roots of control and NaCl-treated plantlets revealed that in the leaves salt stress was associated with decrease or disappearance of some protein bands, and induction of a new protein band after exposure to 100 and 150 mM NaCl. In contrast, NaCl stress had little effect on the protein pattern in the roots. In summary, these findings may provide insight into the mechanisms of the response of woody plants to salt stress.     

Phytochemical screening of flavonoids with their antioxidant activities from rapeseed (Brassica napus L.)

Ten flavone compounds, including three new flavonoid glycosides, were isolated from defatted rapeseed, and their protective antioxidant effect on H₂O₂-induced oxidative damage in human umbilical vein endothelial cells (ECV-304) was investigated. Three new flavonoid glycosides were identified as kaempferol-3-O-[(6-O-sinapoyl)-β-d-glucopyranosyl-(1 → 2)-β-d-glucopyranoside]-7-O-β-d-glucopyranoside (8), kaempferol-3,7-di-O-β-d-glucopyranoside-4'-O-(6-O-sinapoyl)-β-d-glucopyranoside (9), and kaempferol-3-O-[(3-O-sinapoyl)-β-d-glucopyranosyl-(1 → 2)-β-d-glucopyranoside]-7-O-β-d-glucopyranoside (10). The protective effects of all of the isolated compounds on H₂O₂-induced oxidative damage were assessed, and the activities of superoxide dismutase (SOD) and lactate dehydrogenase (LDH) were measured. All of compounds had a protective effect on H₂O₂-induced oxidative damage in ECV-304 cells and the presence of a substituted sinapoyl group and its position in the structures were used to elucidate the activity differences.     

Physiological parameters correlated with Tomato Mosaic Virus inducing defensive response in Datura metel

Programed cell death resembles a real nature active defense in Datura metel against TMV after three days of virus infection. This adaptive plant immune response was quantitatively assessed against Tomato Mosaic Virus infection by the following physiological markers; Chlorophyll-a (mg/g), Chlorophyll-b (mg/g), total protein (mg/g), hydrogen peroxide H₂O₂ (μmol/100 mg), DNA (μg/100 mg), RNA (μg/100 mg), Salicylic acid (μg/g), and Comet Assays. Parameters were assessed for asymptomatic healthy and symptomatic infected detached leaves. The results indicated H₂O₂ and Chlorophyll-a as the most potential parameters. Chlorophyll-a was considered the only significant predictor variant for the H₂O₂ dependent variant with a P value of 0.001 and R-square of 0.900. The plant immune response was measured within three days of virus infection using the cutoff value of H₂O₂ (⩽1.095 μmol/100 mg) and (⩽3.201 units) for the tail moment in the Comet Assay. Their percentage changes were 255.12% and 522.40% respectively which reflects the stress of virus infection in the plant. Moreover, H₂O₂ showed 100% specificity and sensitivity in the symptomatic infected group using the receiver-operating characteristic (ROC). All tested parameters in the symptomatic infected group had significant correlations with twenty-five positive and thirty-one negative correlations where the P value was <0.05 and 0.01. Chlorophyll-a parameter had a crucial role of highly significant correlation between total protein and salicylic acid. Contrarily, this correlation with tail moment unit was (r = −0.930, P < 0.01) where the P value was <0.01. The strongest significant negative correlation was between Chlorophyll-a and H₂O₂ at P < 0.01, while moderate negative significant correlation was seen for Chlorophyll-b where the P value < 0.05. The present study discloses the secret of the three days of rapid transient production of activated oxygen species (AOS) that was enough for having potential quantitative physiological parameters for defensive plant response toward the virus.     

Role of intracellular labile iron,ferritin, and antioxidant defence in resistance of chronically adapted Jurkat T cells to hydrogen peroxide

To examine the role of intracellular labile iron pool (LIP), ferritin (Ft), and antioxidant defence in cellular resistance to oxidative stress on chronic adaptation, a new H₂O₂-resistant Jurkat T cell line “HJ16” was developed by gradual adaptation of parental “J16” cells to high concentrations of H₂O₂. Compared to J16 cells, HJ16 cells exhibited much higher resistance to H₂O₂-induced oxidative damage and necrotic cell death (up to 3 mM) and had enhanced antioxidant defence in the form of significantly higher intracellular glutathione and mitochondrial ferritin (FtMt) levels as well as higher glutathione-peroxidase (GPx) activity. In contrast, the level of the Ft H-subunit (FtH) in the H₂O₂-adapted cell line was found to be 7-fold lower than in the parental J16 cell line. While H₂O₂ concentrations higher than 0.1 mM fully depleted the glutathione content of J16 cells, in HJ16 cells the same treatments decreased the cellular glutathione content to only half of the original value. In HJ16 cells, H₂O₂ concentrations higher than 0.1 mM increased the level of FtMt up to 4-fold of their control values but had no effect on the FtMt levels in J16 cells. Furthermore, while the basal cytosolic level of LIP was similar in both cell lines, H₂O₂ treatment substantially increased the cytosolic LIP levels in J16 but not in HJ16 cells. H₂O₂ treatment also substantially decreased the FtH levels in J16 cells (up to 70% of the control value). In contrast in HJ16 cells, FtH levels were not affected by H₂O₂ treatment. These results indicate that chronic adaptation of J16 cells to high concentrations of H₂O₂ has provoked a series of novel and specific cellular adaptive responses that contribute to higher resistance of HJ16 cells to oxidative damage and cell death. These include increased cellular antioxidant defence in the form of higher glutathione and FtMt levels, higher GPx activity, and lower FtH levels. Further adaptive responses include the significantly reduced cellular response to oxidant-mediated glutathione depletion, FtH modulation, and labile iron release and a significant increase in FtMt levels following H₂O₂ treatment.     

Gene expression of apoptosis-related genes,stress protein and antioxidant enzymes in hemocytes of white shrimp Litopenaeus vannamei under nitrite stress

Apoptotic cell ratio and mRNA expression of caspase-3, cathepsin B (CTSB), heat shock protein 70 (HSP70), manganese superoxide dismutase (MnSOD), catalase (CAT), glutathione peroxidase (GPx) and thioredoxin (TRx) in hemocytes of white shrimp Litopenaeus vannamei exposed to nitrite-N (20 mg/L) was investigated at different stress time (0, 4, 8, 12, 24, 48 and 72 h). The apoptotic cell ratio and mRNA expression level of CTSB were significantly increased in shrimp exposed to nitrite-N for 48 and 72 h. Caspase-3 mRNA expression level significantly increased by 766.50% and 1811.16% for 24 and 48 h exposure, respectively. HSP70 expression level significantly increased at 8 and 72 h exposure. MnSOD mRNA expression in hemocytes up-regulated at 8 and 48 h, while CAT mRNA expression level increased at 24 and 48 h. GPx expression showed a trend that increased first and then decreased. Significant increases of GPx expression were observed at 8 and 12 h exposure. Expression level of TRx reached its highest level after 48 h exposure. These results suggest that nitrite exposure induces expression of apoptosis-related genes in hemocytes, and subsequently caused hemocyte apoptosis. Meanwhile, expression levels of HSP70 and antioxidant enzymes up-regulated to protect the hemocyte against nitrite stress.