Silicon-mediated changes on some physiological and enzymatic parameters symptomatic of oxidative stress in barley grown in sodic-B toxic soil

The effect of silicon (Si) on the growth, sodium (Na), chloride (Cl), boron (B) concentrations, lipid peroxidation (MDA), membrane permeability (MP), lypoxygenase activity (LOX), proline (PRO) and H(2)O(2) accumulation, and the activities of major antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT and ascorbate peroxidase, APX) of barley grown in original sodic-B toxic soil were investigated. Si applied to the sodic-B toxic soil at 70, 140 and 280 mg kg(-1) levels significantly increased Si concentrations of the plants and counteracted the deleterious effects of sodicity (Na ions) and B on shoot growth. Membrane permeability and the concentrations of H(2)O(2) and MDA increased, while PRO concentration decreased in plants grown in sodic-B toxic soil without Si. LOX activity was increased by applied Si. Compared with control plants, the activities of SOD and CAT were decreased, but APX was increased by applied Si levels.     

Interactive effects of salicylic acid and silicon on oxidative damage and antioxidant activity in spinach (<Emphasis Type="Italic">Spinacia oleracea</Emphasis> L. cv. Matador) grown under boron toxicity and salinity

We investigated individual and combined effects of salinity, soil boron (B), silicon (Si) and salicylic acid (SA) on the activities of major antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT and ascorbate peroxidase, APX) and non-enzymatic antioxidants (AA), proline, chlorophyll, anthocyanin, H₂O₂ concentration, stomatal resistance (SR), lipid peroxidation (MDA), membrane permeability (MP), and the uptake of sodium (Na), chloride (Cl), boron and Si of spinach plants. In general, salinity significantly increased H₂O₂ and proline concentrations, antioxidant activity, membrane permeability, lipid peroxidation and SR of the spinach plants, indicating that they were stressed, whereas application of B only increased proline concentration. However, plant fresh weights did not decline with either treatment. The application of Si decreased H₂O₂ and increased the activity of SOD and CAT. The application of SA increased SOD activity. Neither SA nor Si had any effect on the proline concentration, or MP. However, application of Si increased chlorophyll concentration and decreased lipid peroxidation (MDA concentration). Si treatment had no effect on SR. The concentration of B in the tissues, which was strongly increased by B treatment, was decreased by NaCl. As a result of salinity, concentrations of Na⁺ and Cl⁻ ions were increased in the plant tissues, and application of Si slightly increased these concentrations. These results indicate that exogenous Si application increases stress tolerance of spinach, a plant that is naturally reasonably resistant to combined salinity and B toxicity, by the enhancement of antioxidant mechanisms that reduce membrane damage. Exogenous SA has a less obvious effect, although the levels of salinity and boron stress applied were not sufficient in this experiment to reduce plant fresh weight.     

Arbuscular mycorrhizal fungi regulate the oxidative system,hormones and ionic equilibrium to trigger salt stress tolerance in Cucumis sativus L.

Arbuscular mycorrhizal fungi (AMF) association increases plant stress tolerance. This study aimed to determine the mitigation effect of AMF on the growth and metabolic changes of cucumbers under adverse impact of salt stress. Salinity reduced the water content and synthesis of pigments. However, AMF inoculation ameliorated negative effects by enhancing the biomass, synthesis of pigments, activity of antioxidant enzymes, including superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase, and the content of ascorbic acid, which might be the result of lower level lipid peroxidation and electrolyte leakage. An accumulation of phenols and proline in AMF-inoculated plants also mediated the elimination of superoxide radicals. In addition, jasmonic acid, salicylic acid and several important mineral elements (K, Ca, Mg, Zn, Fe, Mn and Cu) were enhanced with significant reductions in the uptake of deleterious ions like Na+. These results suggested that AMF can protect cucumber growth from salt stress.     

No evidence for oxidative stress as a mechanism of action of hyperhomocysteinemia in humans

Oxidative stress has been suggested as one of the physiopathologic conditions underlying the association of total plasma homocysteine (p-tHcy) with cardiovascular disease (CVD), but this hypothesis has not been validated in human epidemiological studies. We measured plasma and erythrocyte antioxidant enzymes glutathione peroxidase (GPx) and superoxide dismutase (SOD), along with serum lipid-soluble antioxidants alpha-tocopherol, beta-carotene, lycopene and retinol, in a sample of 123 healthy elderly subjects (54 men, 69 women). Plasma malondialdehyde (p-MDA) was determined as a marker of lipid peroxidation, and p-tHcy was quantified by HPLC. No significant differences were found for p-MDA, GPx or SOD activities or serum antioxidant concentrations, in subjects with elevated p-tHcy (≥15 μmol/l) as compared to those with lower plasma homocysteine. Hyperhomocysteinemia did not lead to increased risk of having the highest p-MDA values, in either sex. We found no evidence that p-tHcy was associated with lipid peroxidation in this elderly human sample. Our results do not support the view that hyperhomocysteinemia would induce an adaptive response of antioxidant systems, either. More epidemiologic and clinical research is needed to clarify whether homocysteine promotes atherosclerosis by means of an oxidative stress mechanism.     

Silicon increases boron tolerance and reduces oxidative damage of wheat grown in soil with excess boron

The effect of silicon on the growth, boron concentrations, malondialdehyde (MDA) content, lipoxygenase (LOX) activity, proline (PRO) and H₂O₂ accumulation, and the activities of major antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX)] and non-enzymatic antioxidants (AA) of wheat grown in soil originally with toxic B concentrations were investigated. Applied of 5.0 and 10.0 mM Si to the B toxic soil significantly increased Si concentration of the wheat and counteracted the deleterious effects of B on shoot growth. The contents of PRO, H₂O₂, MDA, and LOX activity of wheat grown in B toxic soil were significantly reduced by Si treatments. Compared with control plants, the activities of SOD, CAT, APX and content of AA were decreased by applied Si. Based on the present work, it can be concluded that Si alleviates B toxicity of wheat by preventing oxidative membrane damage and also translocation of B from root to shoot and/or soil to plant.     

Effects of vanadate on male rat reproductive tract histology, oxidative stress markers and androgenic enzyme activities

Vanadium has been recognized as industrial hazards that adversely affect male reproductive systems of humans and animals. However, less information is available concerning the underlying mechanism in the pathogenesis of male reproductive dysfunction. The present study investigated the possible involvement of oxidative stress to induce oxidative deterioration of testicular functions in adult rats. The results of in vitro and in vivo studies demonstrate that vanadium treatment resulted in a significant dose- and time-dependent increase in the testicular lipid peroxidation, marked inhibition in the level of superoxide dismutase and catalase activities, decreased sperm counts, and substantially inhibited the activities of Delta(5)3beta- and 17beta-hydroxysteroid dehydrogenase as well as serum testosterone level. Histopathological examination revealed inhibition of spermatogenesis and the preferential loss of maturing and elongated spermatids along with increased percent of abnormal sperm. Taken together, the results suggest that an increase in free radical formation relative to loss of antioxidant defense system during vanadium exposure may render testis more susceptible to oxidative damage leading to their functional inactivation. Thus the toxic effects of vanadium are cumulative and that vanadium produced damages in testes are dose- and time-dependent.     

Genotoxicity and oxidative stress in fish after a short-term exposure to silver nanoparticles

This study examined the effects of waterborne silver nanoparticles (AgNPs) on juvenile fish Piaractus mesopotamicus (“pacú”), and analyzed toxicological endpoints such as metal burdens, oxidative stress and genotoxicity in a short-term assay. Fish were individually exposed to 0 (control), 2.5, 10, and 25 μg AgNPs/L. After 24 h, silver accumulation was greater in the brain than the liver and gills at all silver concentrations. Fish exposed to higher AgNPs concentrations showed major alterations in oxidative stress markers. An increase in lipid peroxidation (LPO) levels was observed in the liver of fish exposed to 10 μg AgNPs/L with no changes in the antioxidant enzymes activities. In the case of the 25 μg AgNPs/L treatment, a hepatic activation of the enzymatic antioxidant defense occurred, and LPO levels resulted unaltered. On the other hand, the brain presented the highest LPO levels at both 10 and 25 μg AgNPs/L exposures. The AgNPs toxicity was also evidenced by the DNA damage in fish erythrocytes at higher concentrations. Summarizing, a short exposure to sublethal concentrations of AgNPs is enough to generate deleterious effects on fish, including DNA damage.     

Physiological behaviour, oxidative damage and antioxidative protection of olive trees grown under different irrigation regimes

Irrigation effects were investigated on an 8-year-old olive (Olea europaea L., cv. Cobrançosa) commercial orchard located in northeast Portugal. Trees were subjected to a rainfed control (T0) and three treatments (T1, T2, T3) that received a seasonal water amount equivalent to 30%, 60% and 100% of the estimated local evaporative demand by a drip irrigation system. Irrigation increases the photosynthetic activity of olive trees, in association with increases in water status, and reduces the midday and afternoon depression in gas exchange. The closely association between photosynthetic rate (A) and stomatal conductance (g _s) revealed that the decline in net photosynthesis over the course of the day was largely a consequence of stomatal limitation. However, the ratio of intercellular to atmospheric CO₂ concentration increased markedly from morning to midday in non-irrigated plants, in spite of lower g _s, suggesting that non-stomatal limitations of photosynthesis also occur when environmental conditions become more stressful. The occurrence of perturbations at chloroplastic level in rainfed plants was demonstrated by a lower maximum photochemical efficiency of photosystem II during the afternoon. Chlorophyll fluorescence measurements also revealed the occurrence of a dynamic photoinhibition in irrigated trees, mainly in T2 and T3, which seemed to be effective in protecting the photosynthetic apparatus from photodamage. Irrigation enhances antioxidant protection and decreases the oxidative damage at leaf level. Leaves grown under rainfed conditions revealed symptoms of oxidative stress, like the reduction (14%) in chlorophyll concentration and the increased levels (57%) of lipid peroxidation. We also found that the scavenging function of superoxide dismutase was impaired in rainfed plants. In contrast, the low thiobarbituric acid reactive substances concentration in T3 indicates that irrigation enhances the repairing mechanisms and decreases the oxidative damage by lipid peroxidation. Accordingly, leaves in T3 treatment had high levels of –SH compounds and the highest antioxidant potential. Meanwhile, the finding that guaiacol peroxidase activity increased in rainfed plants, associated with the appearance of oxidative damage, suggests that this enzyme has no major antioxidative function in olive.     

Salicylic acid induced changes on some physiological parameters symptomatic for oxidative stress and mineral nutrition in maize (Zea mays L.) grown under salinity

It has been proposed that salicylic acid (SA) acts as an endogenous signal molecule responsible for inducing abiotic stress tolerance in plants. The effect of varying salicylic acid (SA) supply (0, 0.1, 0.5 and 1.0mM) on growth, mineral uptake, membrane permeability, lipid peroxidation, H(2)O(2) concentration, UV-absorbing substances, chlorophyll and carotenoid concentrations of NaCl (40 mM) stressed maize (Zea mays L.) was investigated. Exogenously applied SA increased plant growth significantly both in saline and non-saline conditions. As a consequence of salinity stress, lipid peroxidation, measured in terms of malondialdehyde (MDA) content and membrane permeability was decreased by SA. UV-absorbing substances (UVAS) and H(2)O(2) concentration were increased by increasing levels of SA. SA also strongly inhibited Na(+) and Cl(-) accumulation, but stimulated N, Mg, Fe, Mn and Cu concentrations of salt stressed maize plants. These results suggest that SA could be used as a potential growth regulator to improve plant salinity stress resistance.     

Biochemical markers of oxidative stress in Perna viridis exposed to mercury and temperature

Oxidative damage and antioxidant properties have been studied in Perna viridis subjected to short-term exposure to Hg along with temperature (72h) and long-term temperature exposures (14 days) as pollution biomarkers. The elevated thiobarbituric acid reactive substances (TBA-RS) levels observed in gills and digestive gland under exposure to Hg, individually and combined with temperature, as also long-term temperature stress have been assigned to the oxidative damage resulting in lipid peroxidation (LPX). Increased activities of antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione reductase (GR) and glutathione-S-transferase (GST) both in gills and digestive glands under long-term exposures to temperatures are more prominent to heat rather than cold stress suggesting activation of physiological mechanism to scavenge the ROS produced during heat stress. Also decreased values of reduced glutathione (GSH) on long exposures to temperature stress indicate utilisation of this antioxidant, either to scavenge oxiradicals or act in combination with other enzymes, was more than its production capacity under heat stress. The results suggest that temperature variation does alter the active oxygen metabolism by modulating antioxidant enzyme activities, which can be used as biomarker to detect sublethal effects of pollution.     

Influence of 50 Hz electromagnetic frequency on oxidative stress and morphological characteristics in mosquito-borne filariasis Culex pipiens

The electromagnetic field (EMF) is a vital issue in research, but its use as an alternative technique for insect management is still in its beginnings. The study aimed to evaluate the effects of exposure to the electromagnetic field on the biochemical analysis and morphological characteristics in Culex pipiens. Therefore, the third instar larvae were exposed to EMF frequency (50 Hz) at different intensities (250, 500, 1000 mT) for 1 h during four successive days. After end exposure to EMF, the biochemical analysis, oxidative stress parameters, body weight, and morphological features were investigated. The results showed that larval body weight and total protein content were decreased significantly in all treated groups compared to controls. The total lipid content significantly decreased at 500 & 1000 mT exposure, while the treatment group exposed to EMF at 250 mT was not statistically different compared to control. At a high intensity of EMF 1000 mT all oxidative stress parameters; catalase (CAT) and Glutathione S-transferase (GST) activity and lipid peroxidation level (MDA) were decreased significantly compared to the control. On the other hand, at a low intensity (250 mT), CAT and GST activity was significantly increased, while MDA content was not statistically changed. Scanning electron microscopy showed that both 500 & 1000 mT caused distinct malformations to the larval body parts, mouthparts, thorax and abdomen with last abdominal structures. In conclusion, the results demonstrated that EMF exposure is a considerable stress factor that affects oxidative state and morphological features in mosquitoes and give hope that EMF will be used as an alternative method for Culex pipiens vector control.     

Involvement of oxidative stress and role of antioxidative defense system in growing rice seedlings exposed to toxic concentrations of aluminum

When seedlings of rice (Oryza sativa L.) cultivar Pant-12 were raised in sand cultures containing 80 and 160 μM Al³⁺ in the medium for 5–20 days, a regular increase in Al³⁺ uptake with a concomitant decrease in the length of roots as well as shoots was observed. Al³⁺ treatment of 160 μM resulted in increased generation of superoxide anion (O₂ ⁻) and hydrogen peroxide (H₂O₂), elevated amount of malondialdehyde, soluble protein and oxidized glutathione and decline in the concentrations of thiols (-SH) and ascorbic acid. Among antioxidative enzymes, activities of superoxide dismutase (SOD EC 1.15.1.1), guaiacol peroxidase (Guaiacol POX EC 1.11.1.7), ascorbate peroxidase (APX EC 1.11.1.11), monodehydroascorbate reductase (MDHAR EC 1.6.5.4), dehydroascorbate reductase (EC 1.8.5.1) and glutathione reductase (EC 1.6.4.2) increased significantly, whereas the activities of catalase (EC EC 1.11.1.6) and chloroplastic APX declined in 160 μM Al³⁺ stressed seedlings as compared to control seedlings. The results suggest that Al³⁺ toxicity is associated with induction of oxidative stress in rice plants and among antioxidative enzymes SOD, Guaiacol POX and cytosolic APX appear to serve as important components of an antioxidative defense mechanism under Al³⁺ toxicity. PAGE analysis confirmed the increased activity as well as appearance of new isoenzymes of APX in Al³⁺ stressed seedlings. Immunoblot analysis revealed that changes in the activities of APX are due to changes in the amounts of enzyme protein. Similar findings were obtained when the experiments were repeated using another popular rice cv. Malviya-36.     

Dapsone induces oxidative stress and impairs antioxidant defenses in rat liver

Dapsone (DDS) is currently used in the treatment of leprosy, malaria and in infections with Pneumocystis jirovecii and Toxoplasma gondii in AIDS patients. Adverse effects of DDS involve methemoglobinemia and hemolysis and, to a lower extent, liver damage, though the mechanism is poorly characterized. We evaluated the effect of DDS administration to male and female rats (30 mg/kg body wt, twice a day, for 4 days) on liver oxidative stress through assessment of biliary output and liver content of reduced (GSH) and oxidized (GSSG) glutathione, lipid peroxidation, and expression/activities of the main antioxidant enzymes glutathione peroxidase, superoxide dismutase, catalase and glutathione S-transferase. The influence of DDS treatment on expression/activity of the main DDS phase-II-metabolizing system, UDP-glucuronosyltransferase (UGT), was additionally evaluated. The involvement of dapsone hydroxylamine (DDS-NHOH) generation in these processes was estimated by comparing the data in male and female rats since N-hydroxylation of DDS mainly occurs in males. Our studies revealed an increase in the GSSG/GSH biliary output ratio, a sensitive indicator of oxidative stress, and in lipid peroxidation, in male but not in female rats treated with DDS. The activity of all antioxidant enzymes was significantly impaired by DDS treatment also in male rats, whereas UGT activity was not affected in any sex. Taken together, the evidence indicates that DDS induces oxidative stress in rat liver and that N-hydroxylation of DDS was the likely mediator. Impairment in the activity of enzymatic antioxidant systems, also associated with DDS-NHOH formation, constituted a key aggravating factor.     

Cinnamic acid induced changes in reactive oxygen species scavenging enzymes and protein profile in maize (Zea mays L.) plants grown under salt stress

Plant growth and development are greatly affected due to changes in environmental conditions and become a serious challenge to scientific people. Therefore, present study was conducted to determine the role of secondary metabolites on the growth and development of maize under abiotic stress conditions. Cinnamic acid (CA) is one of the basic phenylpropanoid with antioxidant activity, produced by plants in response to stressful conditions. Response of maize seeds to the presoaking treatment with 0.5 mM CA was studied under different concentrations of NaCl stress. Exogenous CA increased growth characteristics in saline and non-saline conditions, while effects of CA were more significant under saline conditions in comparison to non-saline conditions in maize plants. CA also reduced oxidative damage through the induction of ROS scavenging enzymes such as supperoxide dismutase (SOD) (EC 1.15.1.1), peroxidase (POD) (EC 1.11.1.7), while the activity of enzyme catalase (CAT) (EC 1.11.1.6) was decreased. The content of malondialdehyde (MDA) was reduced significantly in maize leaf under CA treatment. Changes in protein banding patterns in the maize leaves showed a wide variation in response to NaCl-stress, while in the presence of CA salt-induced expression of polypeptides was reduced significantly. Present study clearly reports the alleviative effects of CA in response to salinity stress on growth, metabolic activity and changes in protein profile of 21 days old maize plants.     

Combined effect of salicylic acid and salinity on some antioxidant activities,oxidative stress and metabolite accumulation in <Emphasis Type="Italic">Phaseolus vulgaris</Emphasis>

It has been shown that salicylic acid (SA) acts as an endogenous signal molecule responsible for inducing abiotic stress tolerance in plants. The effect of SA and sodium chloride (NaCl) on growth, metabolite accumulation, oxidative stress and enzymatic and non-enzymatic antioxidant responses on common bean plants (Phaseolus vulgaris, cv. F-15) was studied. Results revealed that either SA or NaCl decrease, shoot, root and total plant dry weights. SA treatments decreased the contents of proline, and reduced forms of ascorbate and glutathione, however, the content of soluble sugars (TSS), thiobarbituric acid-reactive substances (TBARs) and oxidized ascorbate remained unaffected. On the other hand, salinity significantly reduced the levels of endogenous SA but increased the content of proline, soluble sugars, TBARs, ascorbate and glutathione, as well as all increasing the levels of antioxidant enzyme activities assayed, except CAT. The application of SA improved the response of common bean plants to salinity by increasing plant dry weight and decreasing the content of organic solutes (proline and TSS) and damage to the membrane (TBARs). Moreover, SA application under saline conditions decreased the levels of antioxidant enzyme activities POX, APX and MDHAR which could indicate successful acclimatization of these plants to saline conditions.     

Salinity-induced changes in two cultivars of Vigna radiata: responses of antioxidative and proline metabolism

The influence of increasing salinity stress on plant growth, antioxidant enzymes and proline metabolism in two cultivars of Vigna radiata L. (cv. Pusa Bold and cv. CO 4) was investigated. Salt stress was imposed on 30-days-old cultivars with four different concentrations of NaCl (0, 100, 200 and 300 mM). The roots and shoots of CO 4 showed greater reduction in fresh weight, dry weight and water content when compared to Pusa Bold with increasing salt stress. Under salinity stress, the roots and shoots of CO 4 exhibited higher Na⁺: K⁺ ratio than Pusa Bold. The activities of reactive oxygen species (ROS) scavenging enzymes and reduced glutathione (GSH) concentration were found to be higher in the leaves of Pusa Bold than in CO 4, whereas oxidized glutathione (GSSG) concentration was found to be higher in the leaves of CO 4 compared to those in Pusa Bold. Our studies on oxidative damage in two Vigna cultivars showed lower levels of lipid peroxidation and H₂O₂ concentration in Pusa Bold than in CO 4 under salt stress conditions. High accumulation of proline and glycine betaine under salt stress was also observed in Pusa Bold when compared to CO 4. The activities of proline biosynthetic enzymes were significantly high in Pusa Bold. However, under salinity stress, Pusa Bold showed a greater decline in proline dehydrogenase (ProDH) activity compared to CO 4. Our data in this investigation demonstrate that oxidative stress plays a major role in salt-stressed Vigna cultivars and Pusa Bold has efficient antioxidative characteristics which could provide better protection against oxidative damage in leaves under salt-stressed conditions.     

Effects of putrescine and ethephon on some oxidative stress enzyme activities and proline content in salt stressed spinach leaves

The effects of putrescine and ethephon on peroxidase (POD; EC 1.11.1.7), polyphenol oxidase (PPO; EC 1.14.18.1), catalase (CAT; EC 1.11.1.6) activities and proline content in spinach leaves under saline stress were investigated. In control conditions, putrescine increased PPO and CAT activities and proline content, but decreased POD activity. Ethephon increased these three enzyme activities but did not affect proline content. In saline conditions, putrescine increased POD and CAT activities and proline content, while it decreased PPO activity. Ethephon increased both PPO and CAT activities and proline content, but decreased POD activity. Putrescine and ethephon have opposite effects on the enzyme activities and proline accumulation because they acts as antagonists.     

Effect of cryopreservation on sperm parameters, lipid peroxidation and antioxidant enzymes activity in fowl semen

The aim of the present study was to determine the influence of chicken semen cryopreservation on sperm parameters, lipid peroxidation and antioxidant enzymes activities. Pooled semen from 10 Black Minorca roosters was used in the study. Semen samples were subjected to cryopreservation using the “pellet” method and dimethylacetamide (DMA) as a cryoprotectant. In the fresh and the frozen-thawed semen sperm membrane integrity (SYBR-14/propidium iodide (PI)), acrosomal damage (PNA-Alexa Fluor^®488) and mitochondrial activity (Rhodamine 123) were assessed using flow cytometry. Malondialdehyde (MDA) concentration, catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities were determined in sperm cells and seminal plasma by spectrophotometry. All sperm characteristics evaluated using flow cytometry were affected by cryopreservation. After freezing-thawing, there was significant (P < 0.01) reduction in sperm membrane integrity, sperm acrosome integrity and mitochondrial activity. Following cryopreservation, MDA concentration significantly increased in chicken seminal plasma and spermatozoa (P < 0.01, P < 0.05). The CAT activity in seminal plasma significantly decreased (P < 0.05), while intracellular activity of this enzyme did not significantly change in frozen-thawed semen. In seminal plasma of frozen-thawed semen the significant increase (P < 0.01) in GPx activity was detected. Whereas GPx activity in spermatozoa remained statistically unchanged after thawing. The SOD activity significantly increased (P < 0.01) in cryopreserved seminal plasma with simultaneous decrease (P < 0.01) of its activity in cells. In conclusion, this is probably the first report describing the level of antioxidant enzymes in frozen-thawed avian semen. The present study showed that the activity of CAT, GPx and SOD in chicken semen was affected by cryopreservation, what increased the intensity of lipid peroxidation (LPO). Catalase appeared to play an important role in the sperm antioxidant defense strategy at cryopreservation since, opposite to SOD and GPx, its content was clearly reduced by the cryopreservation process. Change in the antioxidant defense status of the chicken spermatozoa and surrounding seminal plasma might affect the semen quality and sperm fertilizing ability.     

Effects of 24-epibrassinolide on seed germination, seedling growth, lipid peroxidation, proline content and antioxidative system of rice (Oryza sativa L.) under salinity stress

The effects of 24-epibrassinolide (24-epiBL) on seedling growth, antioxidative system, lipid peroxidation, proline and soluble protein content were investigated in seedlings of the salt-sensitive rice cultivar IR-28. Seedling growth of rice plants was improved by 24-epiBL treatment under salt stress conditions. When seedlings treated with 24-epiBL were subjected to 120 mM NaCl stress, the activities of superoxide dismutase (EC 1.15.1.1), catalase (EC 1.11.1.6) and glutathione reductase (EC 1.6.4.2) did not show significant difference, whereas the activity of ascorbate peroxidase (EC 1.11.1.11) significantly increased. Increased activity of peroxidase (EC 1.11.1.7) under NaCl stress showed remarkable decrease in the 24-epiBL+NaCl-applied group. Lipid peroxidation level significantly increased under salt stress but decreased with 24-epiBL application revealing that less oxidative damage occurred in this group (24-epiBL+NaCl). In addition, increased proline content in the NaCl-applied group was decreased by 24-epiBL application in the 24-epiBL+NaCl-applied group. Soluble protein content was increased by 24-epiBL application even under NaCl stress, being also higher than control conditions (no 24-epiBL or NaCl treatment). 24-epiBL treatment considerably alleviated oxidative damage that occurred under NaCl-stressed conditions and improved seedling growth in part under salt stress in sensitive IR-28 seedlings.