High Level Of Superoxide Dismutase Activity Research Articles

Application of Cinnamaldehyde Solid Lipid Nanoparticles in Strawberry Preservation

Strawberries are a popular food. However, the growth and reproduction of microorganisms on the surface of strawberries change their quality and may cause food poisoning. We compared the effects of solid lipid nanoparticles containing cinnamaldehyde (SLN-CA) and unencapsulated cinnamaldehyde on the freshness of strawberries stored for seven days. The impacts of SLN-CA at different concentrations on strawberry firmness, weight loss, rate of fruit rot, and sensory quality were investigated at 25 °C. Superoxide dismutase (SOD) and catalase activities and malonaldehyde (MDA) and vitamin C contents of strawberry cell homogenates were measured during storage. The experimental results showed that SLN-CA treatment can effectively reduce the probability of decay in strawberries without causing excessive weight loss. SLN-CA can reduce softening, maintain a high level of SOD activity in cells, reduce the accumulation of MDA and consumption of organic acids, and improve the sensory characteristics of strawberries and thereby their shelf life. Therefore, SLN-CA is a promising preservation method to increase the shelf life and safety of strawberries.

Effects of 4-Week Tangeretin Supplementation on Cortisol Stress Response Induced by High-Intensity Resistance Exercise: A Randomized Controlled Trial.

Objective: This study aimed to investigate the effects of 4-week tangeretin supplementation on the cortisol stress response induced by high-intensity resistance exercise. Methods: A randomized controlled trial of twenty-four soccer players was conducted during the winter training season. The experimental group (EG) took the oral supplement with tangeretin (200 mg/day) and the control group (CG) took placebo for 4 weeks. Before and after the 4-week intervention, all players performed a high intensity bout of resistance exercise to stimulate their cortisol stress responses. Serum cortisol, adreno-corticotropic hormone (ACTH) and superoxide dismutase (SOD) were obtained by collecting blood samples before (PRE), immediately after (P0), and 10 (P10), 20 (P20) and 30 minutes (P30) after the exercise. Results: The serum cortisol level (PRE, p = 0.017; P10, p = 0.010; P20, p = 0.014; P30, p = 0.007) and ACTH (P10, p = 0.037; P30, p = 0.049) of experimental group significantly decreased after the 4-week intervention. Compared with control group, EG displayed a significantly lower level of the serum cortisol (PRE, p = 0.036; P10, p = 0.031) and ACTH (P30, p = 0.044). Additionally, EG presented significantly higher superoxide dismutase activity level compared with CG at P30 (p = 0.044). The white blood cell of EG decreased significantly (PRE, p = 0.037; P30, p = 0.046) and was significantly lower than CG at P20 (p = 0.01) and P30 (p = 0.003). Conclusion: Four-week tangeretin supplementation can reduce serum cortisol and ACTH, which may ameliorate the cortisol stress response in soccer players during high-intensity resistance exercise training. It can also enhance antioxidant capacity, accelerate the elimination of inflammation throughout the body, and shorten recovery time after high-intensity exercise.

Changes in nutrient concentration and oxidative metabolism in pecan leaflets at different doses of zinc

Zinc deficiency limits pecan nut production. The objective of this study was to evaluate changes in nutrient concentration and oxidative metabolism in pecan leaflets in response to the application at different doses of zinc. The foliar concentration of nutrients, leaflet area, total chlorophyll, dry weight (leaflets and root), superoxide dismutase (SOD), hydrogen peroxide, catalase (CAT), guaiacol peroxidase (GP) and antioxidant capacity were evaluated. Statistical analysis indicates that the application of 200 µmol Zn<sup>2+</sup> affected the foliar concentration of N-total (24.50 ± 2.51 g/kg), P (10.34 ± 2.53 g/kg), Fe<sup>2+</sup> (153.33 ± 6.27 mg/kg) and Zn<sup>2+</sup> (42.00 ± 2.84 mg/kg), showing a greater area of the leaflet, total chlorophyll content and dry weight (leaflets and root). Plants treated with 50 µmol Zn<sup>2+</sup> showed a higher level of SOD activity (1.38 ± 0.016 units/min/g), GP (5.56 ± 0.229 nmol glutathione/min/g), and the production of hydrogen peroxide, without exceeding the control. On the other hand, Zn treatments caused a significant decrease in CAT activity. Zn is an essential micronutrient for the growth and development of pecan, which promotes the accumulation of other nutrients. Therefore, its absence affects the generation of oxidative stress with the subsequent activation of the antioxidant defense enzyme system.

PO-113 Long-term Various Load Training Effects on Free Radical Metabolism in the Brain of Aging Mice

Objective To investigate the effects of long-term various load aerobic exercise on the free radical metabolism of the brain in aging mice through the establishment of different swimming exercise models. 
 Methods sixty 3-month-old male Kunming mice were randomly and equally divided into five groups, which were the control group (group C), 10 minute exercise group (group E1), 30 minute exercise group (group E2), 60 minute exercise group (group E3), and 90 minute exercise group (group E4). Group C had regular feeding during the natural aging time in 8 months without any exercise intervention. All other exercise groups performed different load swimming exercise (from 10 to 90 minutes as mentioned above) during the same 8 month period. All subjects were decapitated after exercise on the last day of the 8th month; and the brain tissues were harvested as samples. The malondialdehyde (MDA) amount was measured by the Thiobarbituric Acid method, and the superoxide dismutase (SOD) activity level was measured with Xanthine Oxidase method.
 Results group E3 demonstrated significantly higher SOD activity level and lower MDA amount than the other groups.
 Conclusions Long-term, medium-load aerobic exercise had greatly impacted the metabolism of free radicals in the brain of the mouse, evidenced by increased SOD activity level and decreased MDA production. These effects may indicate that this exercise model may be beneficial in slowing down brain aging by eliminating free radicals and improving brain anti-oxidation ability.

Association of age-related macular degeneration with erythrocyte antioxidant enzymes activity and serum total antioxidant status.

The aim was to estimate association of the oxidative stress with the occurrence of age-related macular degeneration (AMD). The activities of erythrocyte antioxidant enzymes: superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) and additionally serum total antioxidant status (TAS) were used as indicators of the oxidative stress level. 57 AMD patients (32 early and 25 late AMD) and 50 healthy, age and gender matched controls were included. GPx activity (P < 0.001) and serum TAS (P = 0.015) were significantly lower in AMD patients. The difference was not significant for SOD or CAT activities. Significant interaction between GPx and SOD was detected (P = 0.003). At high levels of SOD activity (over 75th percentile), one standard deviation decrease in GPx increases the odds for AMD for six times (OR = 6.22; P < 0.001). ROC analysis revealed that combined values of GPx activity and TAS are significant determinants of AMD status. Accuracy, sensitivity, specificity, and positive and negative predictive values were 75%, 95%, 52%, 69%, and 90%, respectively. The study showed that low GPx activity and TAS are associated with AMD. SOD modulates the association of GPx and AMD. The results suggest that erythrocyte antioxidant enzymes activity and serum TAS could be promising markers for the prediction of AMD.

Uncomplicated malaria infection in pediatric patients in Ghana: relationship with superoxide dismutase

Background: During malaria infection, the superoxide ion is produced as a by-product of hemoglobin digestion by Plasmodium falciparum as well as by the immune cells in defense against the malaria parasite. The ion is toxic to biological systems and adverse effect of the ion is limited when it is dismutated and made harmless by the enzyme superoxide dismutase (SOD). In this study, we investigated the activity of SOD in the context of protection against P.falciparum during uncomplicated malaria infection in pediatric patients. Method: Pediatric patients suffering from uncomplicated malaria and apparently healthy non-infected controls were recruited during malaria season into the study. Blood samples were taken from each participant; hematological indices were measured and parasitemia was quantified. In addition, red blood cells were separated from the blood, lysed, and SOD activity was measured. Results: Significant differences were recorded in levels of white blood cells, particularly lymphocytes, among the uncomplicated malaria patients and control participants. Statistically high levels of SOD activity were observed in uncomplicated malaria patients compared with apparently healthy controls. Partial eta analysis revealed significant and independent influence of polymorphonuclear neutrophils, platelets, mean cell hemoglobin concentration and hemoglobin levels on the SOD activity levels. Conclusion: Uncomplicated malaria was associated with high SOD activity when compared with apparently healthy controls in Ghanaian children.

English

Interesting observation of earlier investigation on regulation of leaf senescence in pigeon pea with serine prompted us to undertake studies on kinetin (Kn)-serine interaction in senescent leaf discs of Spinacia oleracea L., cv. S-23, over time, in the dark to determine their effectiveness individually, and in combination, on photosynthetic pigments, total soluble proteins, lipid peroxidation and activities of the senescence associated enzymes- protease, lipoxygenase (LOX), guaiacol peroxidase (POD) and superoxide dismutase (SOD). Serine and Kn each individually, and in combination, minimized loss in chlorophyll a and b in all days and carotenoids at day 6. Kinetin and serine retarded protein loss and also curtailed protease activity. POD activity increased in untreated leaf discs up to 6-day; SOD activity decreased in control as leaf discs senescence advanced. Senescence increased POD activity and promoted chlorophyll degradation. Serine along with Kn was able to minimize increases in POD and maintained slightly higher level of SOD activity in all days when compared with the control. Although, combined treatment of serine and Kn could lower malondialdehyde content slightly at day 2, LOX activity was reduced. Serine and Kn can scavenge ROS by regulating antioxidant enzymes during leaf senescence. Key words: Spinacia oleracea, chlorophyll, lipid peroxidation, lipoxygenase, superoxide dismutase.

Seasonal-dependent variations in metabolic status of spermatozoa and antioxidant enzyme activity in the reproductive tract fluids of wild boar/domestic pig hybrids.

This study investigated seasonal changes in the metabolic performance of spermatozoa and activity of the antioxidant enzymes in the seminal plasma of three wild boar/domestic pigs (aged 1.5 to 2.5 years) and the activity of the antioxidant enzymes in fluids of the cauda epididymidis and vesicular glands from 16 wild boar/domestic pig hybrids (aged 1 to 3 years). Parameters of the sperm metabolic activity, such as total motility, mitochondrial functions, and measurements of oxygen uptake, ATP content and L-lactate production, were analyzed during the spring-summer and autumn-winter periods. Besides these sperm metabolic parameters, the sperm membrane integrity was also assessed. Total protein content and activity of the antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), were measured in the reproductive tract fluids. There were no marked significant differences (P > 0.05) between the seasonal periods in terms of sperm motility, mitochondrial function and oxygen uptake; however, spermatozoa collected during the autumn-winter period exhibited higher (P < 0.05) ATP content and L-lactate production than those harvested during the spring-summer period. It was found that the vesicular gland fluid exhibited a higher level of SOD activity during the spring-summer period compared with the autumn-winter period. Furthermore, CAT activity in the seminal plasma and vesicular gland fluid was greater during the autumn-winter. Total protein content was significantly higher in the vesicular gland fluid, whereas the cauda epididymidal fluid exhibited greater SOD and GPx activities, irrespective of the seasonal period. The findings of this study confirmed seasonal-related differences in the metabolic performance of spermatozoa and activity of antioxidant enzymes of the reproductive tract of the boar/domestic pig hybrids.

Synthesis of Polymerizable Superoxide Dismutase Mimetics to Reduce Reactive Oxygen Species Damage in Transplanted Biomedical Devices

AbstractA new polymerizable superoxide dismutase (SOD) mimetic metalloporphyrin macromer was synthesized to minimize inflammatory damage associated with tissue transplantation and biomaterial implantation, such as the use of encapsulated pancreatic islets for the treatment of type I diabetes mellitus (TIDM). This functional SOD mimetic, Mn(III) Tetrakis[1‐(3‐acryloxy‐propyl)‐4‐pyridyl] porphyrin (MnTPPyP‐Acryl), was copolymerized and crosslinked with poly(ethylene glycol) diacrylate (PEGDA) to form hydrogel networks that may actively reduce reactive oxygen species (ROS) damage associated with biomaterial implantation. Solution phase activity assays with MnTPPyP‐Acryl macromers showed comparable SOD activity to MnTMPyP, a non‐polymerizable commercially available SOD mimetic. This work also describes the development of a new, simple, and inexpensive solid phase assay system that was developed to assess the activity of MnTPPyP‐Acryl macromers polymerized within PEGDA hydrogels, which has the potential to fulfill an existing void with the biochemical tools available for testing other immobilized ROS antagonists. With this new assay system, hydrogels containing up to 0.25 mol% MnTPPyP‐Acryl showed significantly higher levels of SOD activity, whereas control hydrogels polymerized with inactive TPPyP‐Acryl macromers showed only background levels of activity. The potential for repeated use of such hydrogel devices to consistently reduce superoxide anion concentrations was demonstrated upon retention of ∼100% SOD activity for at least 72 h post‐polymerization. These results demonstrate the potential that polymerizable SOD mimetics may have for integration into medical devices for the minimization of inflammatory damage upon transplantation, such as during the delivery of encapsulated pancreatic islets.

Phototoxic effect of UVR on wild type, ebony and yellow mutants of Drosophila melanogaster: Life Span, fertility, courtship and biochemical aspects

Melanin plays an important role in protecting organisms from ultraviolet radiation (UVR). Therefore, it is possible that differently colored strains can show different sensitivities to UVR. In the present work, life span, fertility and courtship behavior of wild type (w), ebony (e) and yellow (y) strains of Drosophila melanogaster were studied to evaluate their sensitivity to ultraviolet (UV). Because a range of phototoxic effects of UVR are mediated through generation of free radicals, levels of free radicals, lipid peroxide (malondialdehyde, MDA) and superoxide dismutase (SOD) activity of three strains were examined to indicate their antioxidant defending ability and oxidative status. It was shown that w always had the highest lifespan and fertility not only in the control but also in UV-exposed groups. Moreover, lifespan and fertility of e were significantly higher (P<0.0001) than those of y in the UV-exposed groups, but not for the control. On the other hand, UV exposure had an adverse effect on courtship of flies. Stronger electron paramagnetic resonance (EPR) signals could be detected in w, e and y exposed to 5 min UV. And there were more significant changes of EPR signals in y than in w and e. UVR had no significant (P=0.1782) effect on the SOD activities. After pooling data from the control and UV-exposed groups, we found that w had a significantly (P<0.05) higher level of SOD activity, but e and y were nearly at the same levels (P>0.05). MDA levels were increased in the UV dose-dependent manner (P=0.0495). In conclusion, our results suggested that UVR can decrease life span and fertility of flies and do harm to courtship, which may be due to oxidative damage to flies tissues (e.g. central nervous system) induced by free radicals. w had the highest tolerance to UVR, which may be ascribed to its advantage of survival under the natural condition and at high level of SOD activity. Then differences of pigment between e and y in absorbing UV, shielding against UV and scavenging free radicals produced by UVR should be responsible for their different sensitivity to UVR.

Over expression of cytosolic copper/zinc superoxide dismutase from a mangrove plant Avicennia marina in indica Rice var Pusa Basmati-1 confers abiotic stress tolerance

Antioxidant enzymes play an important role in conferring abiotic stress tolerance. Superoxide dismutase (SOD) is the first enzyme in the enzymatic antioxidative pathway. Halophytic plants like mangroves have been reported to have a high level of SOD activity, which plays a major role in defending the mangrove species against severe abiotic stresses. We had previously reported the isolation of Sod1, a cDNA encoding a cytosolic copper zinc superoxide dismutase from the mangrove plant Avicennia marina and its mRNA expression pattern during various oxidative and abiotic stresses. The present study is an extension of the previous study in further characterizing the Sod1 cDNA by transforming it into rice and analysing the transgenic plants for abiotic stress tolerance. Southern hybridization of A. marina genomic DNA using Sod1, revealed that this gene in A. marina genome is present as a single copy. The cDNA was cloned into a binary vector (pCAMBIA 1300) and transformed into indica rice var Pusa Basmati-1. Southern hybridization analysis of transgenic rice plants revealed stable integration of the Sod1 transgene in the rice genome. The mRNA transcript of Sod1 was detected by Northern hybridisation in the transgenic rice plants. SOD isozyme assay of the transgenic rice plants revealed the stable expression of the transgenic Sod1 protein. The transgenic plants were more tolerant to methyl viologen mediated oxidative stress in comparison to the untransformed control plants. The transgenic plants also withstood salinity stress of 150 mM of NaCl for a period of eight days while the untransformed control plants wilted at the end of the stress treatment in hydroponics. Pot grown transgenic plants could also tolerate salinity stress better than the untransformed control plants, when irrigated with saline water. The transgenic plants also revealed better tolerance to drought stress in comparison to untransformed control plants.

Superoxide dismutase activities in long-lived Drosophila melanogaster females: chico 1 genotypes and dietary dilution

Superoxide dismutase (SOD) activities were determined for dietary dilution conditions that extend the life span of Drosophila melanogaster. The hypothesis motivating this research was that elevated SOD activity is associated with increased life span resulting from flies being held on a restricted diet. SOD activities were also measured for chico (1) which is a mutation in the insulin receptor substrate protein gene associated with life span extension. This allowed us to confirm the results of (Clancy et al. 2001) and extend the results by measuring CuZn SOD and Mn SOD activities in addition to the previously determined overall SOD activity. If the same form of SOD activity (CuZn SOD or Mn SOD) was elevated on the dilute diet that extends life span and in the long lived chico (1) homozygotes, then it would suggest that life span extension by dietary restriction and by insulin signaling mutations has a similar underlying mechanism. However, overall SOD activity, and CuZn SOD or Mn SOD activities did not differ among the diets tested. As observed previously (Clancy et al. 2001), overall SOD activity was elevated in chico (1) homozygotes compared to the heterozygote or wild type. Results from the present study indicate that elevated CuZn SOD activity, not Mn SOD, is the basis for the relatively high level of SOD activity in the chico (1) homozygotes.

Effects of microcystins on and toxin degradation by Poterioochromonas sp.

A Chrysophyceae species, Poterioochromonas sp., was isolated from Microcystis cultures. This species can efficiently prey on Microcystis and can grow faster phagotrophically than autotrophically. The growth of Poterioochromonas sp. was stimulated in the presence of microcystin-LR and microcystin-RR (in concentrations ranging from 0.1 to 4 mg/L). The growth rate of Poterioochromonas was 4-5 times higher than the control, indicating the toxins serve as growth stimuli for this organism. A subculture of toxin-treated cells, however, showed low cellular viability, suggesting that growth enhancement by microcystins was not a normal process. The antioxidant enzymatic activity of Poterioochromonas sp. was screened for toxicology analysis. Glutathione, malondialdehyde, and superoxide dismutase (SOD) content was up-regulated within 8 h of exposure to microcystin-LR (500 microg/L). A high level of SOD activity during exposure to the toxin indicated that SOD was involved in decreasing oxidative stress caused by microcystin-LR. Simultaneously with growth, Poterioochromonas was able to degrade microcystin-LR even, at a toxin concentration of 4 mg/L. This putative degradation mechanism in Poterioochromonas is explored further and discussed in this article. Our findings may shed light on understanding the role of Poterioochromonas in the aquatic ecosystem, in particular, as a grazer of toxic cyanobacteria and a biodegrader for microcystins.

Antioxidant enzymatic defences in human follicular fluid: characterization and age-dependent changes.

The aim of this work was to study the antioxidant enzymatic defences in human follicular fluid and investigate their possible changes during reproductive ageing. To this end, we tested the specific activities and protein expression of enzymes involved in reactive oxygen species (ROS) scavenging and in detoxification of ROS byproducts in follicular fluid from young (range 27-32 years, n = 12) and older (range 39-45 years, n = 12) women participating in an IVF programme. Results show that all the tested enzymes [superoxide dismutase (SOD), catalase, glutathione peroxidase, glutathione transferase, glutathione reductase] were significantly expressed in human follicular fluid. However, when the two age groups were compared, we found that follicular fluid from older women exhibited a reduced level of glutathione transferase and catalase activities and a higher level of SOD activity. Immunoblot analysis revealed that ageing was associated with decreased protein expression of GST Pi isoform and did not affect SOD and catalase protein expression. Taken together, these findings indicate that reproductive ageing is accompanied by a change in the antioxidant enzymatic pattern that could impair ROS scavenging efficiency in the follicular environment.

Role of superoxide dismutase in individualization of breast cancer radiation therapy protocols

Background: The goal of this study was to introduce a new predictive biomarker assay that might improve a clinical irradiation treatment of malignant diseases. Methods: Thirty-two peripheral blood samples obtained from breast cancer patients were analyzed for superoxide dismutase (SOD) after irradiation with gamma rays (60 Co). SOD was measured in subcellular fractions prepared from unirradiated and irradiated blood samples (McCord and Fridovich). The activity of SOD was measured by the method of Misra and Fridovich and protein concentration by the method of Lowry et al. Results Antioxidant radiation response of patients' blood cells was very variable and specific for each individual. The results indicated that the radiation response during radiotherapy directly depends on the initial state of antioxidant activity in the blood of cancer patients. In the blood samples with high level of SOD activity the irradiation decreased enzymatic activity while in the samples with medium or low level of SOD, the SOD activity was preserved or increased by irradiation with 2 Gy of gamma rays. Conclusion We showed that the modulation of SOD activity in blood cells after irradiation in vitro might be used as predictive biomarker in individualization of therapy protocols.

Superoxide dismutase activity in human follicular fluid after controlled ovarian hyperstimulation in women undergoing in vitro fertilization

Objective: To determine the activity of superoxide dismutase (SOD) and the total protein concentration in human preovulatory ovarian follicular fluid (FF) in relation to corresponding serum levels and the fertilization capacity of oocytes. Design: Prospective, observational study. Setting: Academic-based center for reproductive medicine. Patient(s): Twenty-eight female partners of infertile couples, 13 of whom were smokers, undergoing controlled ovarian hyperstimulation for IVF. Intervention(s): Blood and follicular fluid samples were collected 34–36 hours after hCG administration. Main Outcome Measure(s): Levels of SOD activity and total protein concentrations. Result(s): Superoxide dismutase activity was present in all the FF studied and mean levels were statistically significantly higher than in serum. Total protein concentrations in serum were statistically significantly correlated with corresponding concentrations in FF. There was no difference in SOD activity between smokers and nonsmokers. Total protein concentrations in FF were marginally and statistically significantly lower in nonsmokers. Follicular fluid from patients whose oocytes did not become fertilized had a statistically significantly higher level of SOD activity than that from patients whose oocytes did become fertilized. Conclusion(s): Superoxide dismutase activity is present in FF and is higher than in serum. The degree of SOD activity is variable and seems to be inversely related to the fertilization of oocytes.

Superoxide Anion Radical Production as a Cadmium-Mediated Mechanism of Toxicity in Avian Thyroid: An Electron Spin Resonance Study by Spin Trapping

Cadmium (Cd) induced superoxide anion radical (O ·− 2) generation in vivo has been demonstrated in the thyroid gland of Columba livia intermedia by electron spin resonance (ESR) spin trapping. A single dose of Cd caused generation of O ·− 2, elevated lipid peroxidation (LPO) and superoxide dismutase (SOD) activity and depletion of glutathione (GSH) content in the thyroid gland on the 1st and 3rd day after the treatment. After the 7th and 10th day of Cd intoxication, the thyroid gland resumes normal reducing atmosphere characterized by a very low LPO level, total decay of O ·− 2 and an adaptive recovery of depleted GSH to that of control. A high level of SOD activity over the experimental period and return of GSH content to that of control by the 7th day of treatment till the 10th day suggest their role as a very effective oxyradical scavenging sink during Cd-mediated oxidative assault. A low plasma triiodothyronine (T 3) level, decreased plasma T 3/T 4 ratio over most of the study period and a transient drop in plasma thyroxine (T 4) level during early phase of acute poisoning indicate that pigeons are in the hypothyroid state. We propose that avian thyroid dysfunction under acute Cd-exposure is due to impaired thyroid hormonogenesis under an oxidative stress and a direct Cd-inhibition of peripheral monodeiodination of T 4 to T 3.

Oxidative stress in Agrobacterium‐induced tumors on Kalanchoe plants

The induction of tumor formation by wild‐type Agrobacterium tumefaciens was found to be associated with the apparent rate of production of superoxide anions (O2°−) in the infected tissue of Kalanchoe plants. The transcript levels of MnSOD and Cu/ZnSOD and the specific activity of superoxide dismutase (SOD) during different stages of tumor induction support this. A. tumefaciens strain with mutations in the cytokinin biosynthetic gene produced delayed, smaller and abnormal tumors which underwent significantly lower levels of superoxide stress compared with normal tumors, produced by the wild‐type strain. These suppressed tumors developed into normal tumors with the concurrent production of O2°− when supplemented in vitro with exogenous phytohormones. Phytohormone‐induced callus from non‐infected stem tissues maintained in vitro in the presence of phytohormones produced O2°− in the same order of magnitude as the tumor cells. Transgenic plants expressing three‐ to five‐fold higher levels of SOD activity exhibited a 55% reduction in the apparent rate of O2°− production compared with that of the non‐transgenic plants when challenged with wild‐type Agrobacterium. These results suggest the possible role of phytohormones in creating superoxide stress which, in turn, may cause deregulation of cell division, oncogenicity and ultimately tumor formation.

Superoxide dismutase (SOD) activity ofDictyocaulus viviparusand its inhibition by antibody from infected and vaccinated bovine hosts

The presence of superoxide dismutase (SOD) activity in the bovine lungworm Dictyocaulus viviparus was examined using the xanthine-xanthine oxidase assay system and by non-denaturing PAGE followed by specific enzyme staining. High levels of activity were detected in excretory-secretory (ES) products of adult worms and in soluble extracts of both the L3 and adult stages of the parasite. Stage-specific and ES-specific activities were indicated by differences in SOD isoenzyme profiles between adult and larval parasite extracts and between adult extract and ES products, with a fast migrating activity being specific to ES products. All isoenzymes were sensitive to cyanide, indicating copper/zinc dependency. The antigenicity of ES SOD was demonstrated by a reduction in SOD activity in both the chemical assay and non-denaturing PAGE following incubation of parasite ES products with IgG antibody purified from serum of infected or vaccinated bovine hosts. The high level of SOD activity released by adult D. viviparus may be a reflection of the problems faced by a parasite occupying an oxygen-rich environment. Antibody inhibition of SOD may, therefore, be an important target of protective immunity.

Oxidative stress and ageing in Caenorhabditis elegans.

Mutations in the age-1 gene double both the mean and maximum life span of Caenorhabditis elegans. They also result in an age-specific increase of catalase and Cu/Zn superoxide dismutase activity levels. The higher superoxide dismutase activity levels in age-1 mutants confer hyperresistance to the superoxide-anion-generating drug paraquat. The rate of superoxide anion production by microsome fractions declines linearly with age in age-1(+) worms, but, after an initial decline, is stabilized at a higher level in senescent age-1 mutant nematodes. These results clearly show that oxidative stress resistance and potential life span are correlated in this organism, and they suggest that the natural product of age-1 either directly or indirectly downregulates the activities of several other genes as a function of age.