Effect of TiO2 nanoparticles on oxidative damage and antioxidant defense systems in chickpea seedlings during cold stress

The effects of TiO₂ nanoparticles (NPs) on physiologo-biochemical responses were studied in two chickpea (Cicer arietimun L.) genotypes differing in cold sensitivity (tolerant Sel11439 and sensitive ILC533) during cold stress (CS). The results showed that hydrogen peroxide and MDA contents and electrolyte leakage index (ELI) increased under CS conditions in both genotypes and that these damage indices were higher in ILC533 than in Sel11439 plants. In plants treated with TiO₂ NPs, a decreased H₂O₂ level was accompanied by a decrease in the MDA content and ELI compared to control plants, and these changes occurred more effectively in Sel11439 than in ILC533 plants. The antioxidant enzymes were more effective in cell protection against CS in Sel11439 plants compared to ILC533 plants, as well as in plants treated with TiO₂ NPs compared to control plants. The lipoxygenase activity was induced efficiently only in Sel11439 plants treated with TiO₂ NPs during CS, probably indicating its role in stress response (which was confirmed by measuring allen oxide synthase activity). TiO₂ NPs caused stability of chlorophyll and carotenoid contents during CS. Results suggest that TiO₂ NPs confer an increased tolerance of chickpea plants to CS, decreasing the level of injuries and increasing the capacity of defense systems.     

Effect of cold acclimation on antioxidant status in cold acclimated skaters

We investigated whether cold acclimation leads to increased activity of the antioxidant defense enzymes and muscle injury. Comparisons were between short track skaters (n=6) and inline skaters (n=6) during rest and at submaximal cycling (65% VO2max) in cold (ambient temperature: 5+/-1 degrees C, relative humidity: 41+/-8%) and warm conditions (ambient temperature: 21+/-1 degrees C, relative humidity: 35+/-5%), during 60 min, respectively, and during the recovery phase. Erythrocyte superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSHpx), reduced glutathione (GSH), thiobarbituric substance acid (TBARS), serum creatine kinase (CK), lactate dehydrogenase (LDH), plasma myoglobin (Mb) and cortisol were determined. Activities of CAT and GSHpx and the level of GSH and TBARS in erythrocyte and the level of LDH in serum were elevated in cold acclimated subjects. We suggested that the compensatory increase in antioxidative defense enzymes resulting from long-term cold exposure may reflect the elevated reactive oxygen species (ROS) production and muscle injury at this environment acclimation.     

Water stress-induced oxidative damage and antioxidant responses in micropropagated banana plantlets

Oxidative injury and antioxidant responses were investigated in two banana genotypes (Musa AAA Berangan and Musa AA Mas) subjected to 40 % PEG-induced water stress. PEG treatment resulted in oxidative injury, as expressed in increased lipid peroxidation and reduced membrane stability index, in both cultivars; however, greater oxidative injury was detected in Mas. Under PEG treatment, catalase activity and glutathione reductase activity were enhanced in both cultivars, but were higher in Mas. Ascorbate peroxidase activity was enhanced in Berangan under water stress, but was unaffected in Mas. Meanwhile, superoxide dismutase activity was inhibited in both cultivars under water stress, but higher activity was detected in Berangan. Higher ascorbate peroxidase and superoxide dismutase activities were associated with greater protection against water stress-induced oxidative injury.     

Cadmium-induced oxidative damage and antioxidant responses in Brassica juncea plants

Indian mustard (Brassica juncea L. cv. Vitasso) plants exposed to 10, 30, 50 and 100 μM of Cd for 5 d in hydroponic culture were analysed with reference to the distribution of Cd²⁺, the accumulation of biomass and antioxidants and antioxidative enzymes in leaves. Cd induced a decrease in plant biomass. The maximum accumulation of Cd occurred in roots followed by stems and leaves. Cd induced a decrease in catalase (CAT) and guiacol peroxidase (GPX) activities but an increase in ascorbate peroxidase (APX) and monodehydroascorbate reductase (MDHAR) activities. Enhancement in dehydroascorbate reductase (DHAR) activity was also at 10 μM Cd. Glutathione reductase (GR) activity showed pronounced stimulation after all treatments, but glutathione S-transferase (GST) and glutathione peroxidase (GPOX) activities decreased. The effectiveness of ascorbate-glutathione cycle (AGC) was determined by the ratio of ascorbate to H₂O₂. This ratio decreased in the Cd-treated leaves which indicated that the cycle was disordered.     

Lymphocyte enzymatic antioxidant responses to oxidative stress following high-intensity interval exercise

The purposes of this study were to 1) examine the immune and oxidative stress responses following high-intensity interval training (HIIT); 2) determine changes in antioxidant enzyme gene expression and enzyme activity in lymphocytes following HIIT; and 3) assess pre-HIIT, 3-h post-HIIT, and 24-h post-HIIT lymphocyte cell viability following hydrogen peroxide exposure in vitro. Eight recreationally active males completed three identical HIIT protocols. Blood samples were obtained at preexercise, immediately postexercise, 3 h postexercise, and 24 h postexercise. Total number of circulating leukocytes, lymphocytes, and neutrophils, as well as lymphocyte antioxidant enzyme activities, gene expression, cell viability (CV), and plasma thiobarbituric acid-reactive substance (TBARS) levels, were measured. Analytes were compared using a three (day) × four (time) ANOVA with repeated measures on both day and time. The a priori significance level for all analyses was P < 0.05. Significant increases in superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) activities were observed in lymphocytes following HIIT. No significant increases in lymphocyte SOD, CAT, or GPX gene expression were found. A significant increase in TBARS was found immediately post-HIIT on days 1 and 2. Lymphocyte CV in vitro significantly increased on days 2 and 3 compared with day 1. Additionally, there was a significant decrease in CV at 3 h compared with pre- and 24 h postexercise. These findings indicate lymphocytes respond to oxidative stress by increasing antioxidant enzyme activity. Additionally, HIIT causes oxidative stress but did not induce a significant postexercise lymphocytopenia. Analyses in vitro suggest that lymphocytes may become more resistant to subsequent episodes of oxidative stress. Furthermore, the analysis in vitro confirms that lymphocytes are more vulnerable to cytotoxic molecules during recovery from exercise.     

Effect of salinity on antioxidant responses of chickpea seedlings

The changes in the activity of antioxidant enzymes, like superoxide dismutase, ascorbate peroxidase, catalase and glutathione reductase, and growth parameters such as length, fresh and dry weight, proline and H₂O₂ contents, chlorophyll fluorescence (Fv/Fm), quantum yield of PSII and the rate of lipid peroxidation in terms of malondialdehyde in leaf and root tissues of a chickpea cultivar (Cicer arietinum L. cv. Gökçe) under salt treatment were investigated. Plants were subjected to 0.1, 0.2 and 0.5 M NaCl treatments for 2 and 4 days. Compared to controls, salinity resulted in the reduction of length and of the fresh and dry weights of shoot and root tissues. Salinity caused significant (P < 0.05) changes in proline and MDA levels in leaf tissue. In general, a dose-dependent decrease was observed in H₂O₂ content, Fv/Fm and quantum yield of photosynthesis under salt stress. Leaf tissue extracts exhibited three activity bands, of which the higher band was identified as MnSOD and the others as FeSOD and Cu/ZnSOD. A significant enhancement was detected in the activities of Cu/ZnSOD and MnSOD isozymes in both tissues. APX and GR activities exhibited significant increases (P < 0.05) in leaf tissue under all stress treatments, whereas no significant change was observed in root tissue. The activity of CAT was significantly increased under 0.5 M NaCl stress in root tissue, while its activity was decreased in leaf tissue under 0.5 M NaCl stress for 4 days. These results suggest that CAT and SOD activities play an essential protective role against salt stress in chickpea seedlings.     

Survivorship of geographic Pomacea canaliculata populations in responses to cold acclimation

1. Pomacea canaliculata, a freshwater snail from South America, has rapidly established natural populations from south to north subtropical region in China, since its original introductions in the 1980s. Low temperature in winter is a limiting factor in the geographic expansion and successfully establishment for apple snail populations. There have been some studies on population level of low temperature tolerance for P. canaliculata, yet little is quantified about its life‐history traits in responses to cold temperatures. Whether these responses vary with the acclimation location is also unclear. We investigated the survivorship and longevity of P. canaliculata in responses to cold temperatures and examine whether these responses vary with the location and snail size. We hypothesized that survival of the snails depends on their shell height and the level of low temperature, and P. canaliculata population from the mid-subtropical zone may exhibit the highest viability over the cold thermal range.
2. We sampled P. canaliculata populations from five latitude and longitude ranges of subtropical China: Guangzhou population in southernmost (SM‐GZ), three populations of Yingtan (MR‐YT), Ningbo (MR‐NB), Ya'an (MR‐YA) in midrange, and Huanggang population in northernmost (NM‐HG) subtropical zone. For each P. canaliculata population, survival and longevity at six cold acclimation temperature levels (12, 9, 6, 3, 0, and ?3°C) were quantified, and the effects of location and shell height were examined.
3. The MR‐YA population from mid-subtropical zone of China exhibited the highest survival rate and prolonged survival time regardless of the temperature acclimation treatments, whereas the SM‐GZ population from southern subtropical was the most sensitive to cold temperatures, particular temperatures below 9°C. No individuals of the SM‐GZ population could survive after stressed for 30 days (3°C), 5 days (0°C) and 2 days (?3°C), respectively. For each experimental P. canaliculata population held at 3, 0, and ?3°C, individuals with intermediate shell height of 15.0–25.0 mm had significantly higher survivals.
4. The results highlight a request of a more thorough investigation on acclimation responses in each of the life table demographic parameters for P. canaliculata, and pose the question of whether natural selection or some genetic changes may have facilitated adaptation in invasive locations.

     

Change in membrane fatty acid compositions and cold-induced responses in chickpea

Plant cells often increase cold tolerance by reprogramming their genes expression which results in adjusted metabolic alternations, a process enhanced under cold acclimation (CA) phase. In present study, we assessed the changes of membrane fatty acid compositions and defense machine (like antioxidative enzymes) along with damage indexes like electrolyte leakage index (ELI) and malondialdehyde (MDA) during CA, cold stress (CS) and recovery (R) phases in chickpea (Cicer arietinum L.). Results showed an increase in unsaturated fatty acids ratio compare to saturated ones which is a sign of cold tolerance especially after CA phase. Antioxidant enzymes had an important role during CA and R phases while CS affected their activity which can be a sign for associating other metabolites or enzymes activities to create cold tolerance in plants. To investigation of enzymes assay under experimental treatments, the expression pattern of some enzymes including superoxide dismutase (sod), catalase (cat) and lipoxygenase (lox) was studied using quantitative real time PCR. LOX activity has shown a bilateral behavior: a positive relation with membrane damage index in CA and an interesting link with double bond index (DBI) in CS indicating probably its role in secondary metabolites like jasmonic acid signaling pathway. It was suggested that increased DBI and low LOX activity under CS could be a reason for plant cold tolerance.     

Effects of short-term heat stress on oxidative damage and responses of antioxidant system in Lilium longiflorum

This paper aims to determine the changes in reactive oxygen species (ROS) and the responses of the lily (Lilium longiflorum L.) antioxidant system to short-term high temperatures. Plants were exposed to three levels of heat stress (37°C, 42°C, 47°C) for 10 h when hydrogen peroxide (H₂O₂) and superoxide (O₂⁻) production rate along with membrane injury indexes, and changes in antioxidants were measured. Compared with the control (20°C), electrolyte leakage and MDA concentration varied slightly after 10 h at 37°C and 42°C, while increased significantly at 47°C. During 10 h at 37°C and 42°C, antioxidant enzyme activities, such as SOD, POD, CAT, APX and GR, were stimulated and antioxidants (AsA and GSH concentrations) maintained high levels, which resulted in low levels of O₂⁻ and H₂O₂ concentration. However, after 10 h at 47°C, SOD, APX, GR activities and GSH concentration were similar to the controls, while POD, CAT activities and AsA concentration decreased significantly as compared with the control, concomitant with significant increase in O₂⁻ and H₂O₂ concentrations. In addition, such heat-induced effects on antioxidant enzymes were also confirmed by SOD and POD isoform, as Cu/ZnSOD maintained high stability under heat stress and the intensity of POD isoforms reduced with the duration of heat stress, especially at 47°C. It is concluded that in lily plants, the oxidative damage induced by heat stress was related to the changes in antioxidant enzyme activities and antioxidants.     

DNA damage responses to oxidative stress

The DNA damage response is a hierarchical process. DNA damage is detected by sensor proteins such as the MRN complex that transmit the information to transducer proteins such as ATM and ATR, which control the damage response through the phosphorylation of effector proteins. The extent of the DNA damage determines cell fate: cell cycle arrest and DNA repair or the activation of apoptotic pathways. In aerobic cells, reactive oxygen species (ROS) are generated as a by-product of normal mitochondrial activity. If not properly controlled, ROS can cause severe damage to cellular macromolecules, especially the DNA. We describe here some of the cellular responses to alterations in the cellular redox state during hypoxia or oxidative stress. Oxidative damage in DNA is repaired primarily via the base excision repair (BER) pathway which appears to be the simplest of the three excision repair pathways. To allow time for DNA repair, the cells activate their cell cycle checkpoints, leading to cell cycle arrest and preventing the replication of damage and defective DNA.     

The oxidative stress and antioxidant systems in cucumber cells during acclimation to salinity

In the present study, we measured the markers of oxidative stress as well as activity of antioxidative enzymes and content of α-tocopherol in the acclimated and non-acclimated cucumber (Cucumis sativus L.) cell suspension cultures subjected to 150 and 200 mM NaCl. The content of carbonyl groups and lipid peroxidation were lower in the acclimated cultures than in the non-acclimated ones as well as their increases after NaCl treatments. Both NaCl concentrations enhanced activity of glutathione peroxidase in the examined cultures whereas activity of glutathione-S-transferase rose only in the acclimated ones. The increase in content of α-tocopherol induced by NaCl was more pronounced in the acclimated cultures. NaCl caused high decline in cell vigour in the non-acclimated cultures up to 80–90 % at the end of the experiment. The presented data suggest that the acclimated cultures coped with the salt stress better than the non-acclimated ones.     

Hydroxy-urea protects erythrocytes against oxidative damage

Hydroxy-urea (OH-U) is used to treat sickle cell anemia by increasing hemoglobin fetal-fraction. It has been suggested that the sickle cell mutations lead to the formation of unstable HbS and release of iron, which can result in lipid peroxidation (LPO), and eventual cell damage. Since oxidative processes might be involved in pathogenesis of sickle cell disease, we investigated the antioxidant property of OH-U in a red blood cell (RBC) model. Intact RBCs or RBC membranes were exposed to t-butyl hydroperoxide (t-BHP, 0.75 mM) or iron (ferrous sulfate; 100 microM) at 37 degrees C for 60 min in the presence or absence of OH-U (1.25 mM). The extent of oxidative damage was measured by LPO (as thiobarbituric acid reactive substances, TBARS), hemoglobin oxidation (as percent of methemoglobin, metHb %), and decrease in the activities of membrane-bound Na+/K+-ATPase and Ca2+-ATPases. Our results show that OH-U inhibited t-BHP-induced LPO in fresh RBC membranes significantly (P <0.01). OH-U significantly inhibited t-BHP-mediated LPO (P <0.01) and metHb formation (P <0.01) in intact RBC. Also, OH-U inhibited iron-induced LPO and metHb formation in intact RBC (P <0.01). In addition, OH-U blocked t-BHP-mediated changes in membrane ATPase activities. Furthermore, OH-U blocked iron-mediated hydroxyl radical generation in a dose-dependent fashion. In conclusion, the observed antioxidant properties of OH-U might contribute to its therapeutic action in sickle cell disease.     

PSII photochemistry and antioxidant responses of a chickpea variety exposed to drought

The effect of drought on the chickpea variety ILC 3279 was investigated at the vegetative stage. After 20 days from sowing, the plants subjected to drought stress for 3, 5 and 7 days imposed by withholding water were permitted to recover by rewatering for 2 days after 3, 5 and 7 days of drought. Shoot elongation, leaf production, fresh and dry biomass reduced while MDA and proline accumulation increased with extended duration of stress. The plants stressed for 3 days exhibited a rapid drop in their relative and absolute water contents. The quantum efficiency of PSII open centres in the dark-adapted and light-saturated state, excitation energy trapping of PSII and electron transport rate decreased significantly from the 5th day to the end of the drought treatments. Plants drought-stressed for 7 days brought about a marked increase in non-photochemical energy dissipation and a marked decline in photochemical quenching. After rewatering all chlorophyll a fluorescence characteristics except for F(M) completely recovered and reached the control values. Under 5 and 7 days of drought, the anthocyanin content increased gradually while the total chlorophyll content of leaves declined compared to the controls. The total carotenoid content remained unchanged during the experiments. The antioxidant enzyme response to drought treatments was quite variable. The total SOD activity upregulated with increasing duration of stress. On the other hand, the total APX activity was significantly higher only on the 7th day while the total POD activity increased from the 5th day. Differences in the total GR activity of treated groups were not statistically significant compared to their controls throughout the treatments. The present results indicate that the chickpea variety ILC 3279 withstands severe drought with its upregulated protective mechanisms at the vegetative stage.     

Nicotinamide (vitamin B3) as an effective antioxidant against oxidative damage in rat brain mitochondria

Nicotinamide (vitamin B3) an endogenous metabolite, showed significant inhibition of oxidative damage induced by reactive oxygen species (ROS) generated by ascorbate-Fe2+ and photosensitization systems in rat brain mitochondria. It protected against both protein oxidation and lipid peroxidation, at millimolar concentrations. Inhibition was more pronounced against oxidation of proteins than peroxidation of lipids. Chemically related endogenous compounds, tryptophan and isonicotinic acid, showed comparable inhibitory properties. The protective effect observed, at biologically relevant concentrations, with nicotinamide was more than that of the endogenous antioxidants ascorbic acid and alpha-tocopherol. Hence our studies suggest that nicotinamide (vitamin B3) can be considered as a potent antioxidant capable of protecting the cellular membranes in brain, which is highly susceptible to prooxidants, against oxidative damage induced by ROS.