Oxidative stress during selenium deficiency in seedlings of Trigonella foenum-graecum and mitigation by mimosine. Part I. Hydroperoxide metabolism.
TL;DR: The results including the differential response of GR activity to Se or mimosine supplementation are reflective of an effective reductive environment in Se groups and increased turnover of GSH in the presence of Mimosine.
Abstract: Actaptive alterations in glutathione (GSH) metabolism were studied during oxidative stress induced by selenium (Se) deficiency in germinating seedlings ofTrigonella foenum- graecum grown for 72 h and the response to supplementation individually of Se or mimosine was explored. Growth enhancement with improved mitochondrial efficiency was elicited by supplementation of Se at 0.5-0.75 ppm or mimosine at 0.1-0.2 mM. Total thiol and protein levels of mitochondrial and soluble fractions, in general, did not vary significantly with supplementation of either Se or mimosine except that the mitochondrial protein levels in mimosine groups (0.1-0.2 mM) decreased by 20–30%. Mitochondrial glutathione peroxidase (GSH-Px) increased by twofold in activity toward H2O2, cumene hydroperoxide (CHP), and t-butyl hydroperoxide (tBHP) in Se groups, and by 50–60% increase toward H2O2 and CHP but by a twofold enhancement in enzyme activity with tBHP in mimosine groups. Soluble GSH-Px activity increased by 30–40% only in mimosine groups and remained unaltered in Se groups. Glutathione S-transferase activity (GST) in the soluble fraction of both Se and mimosine groups increased dramatically by fivefold to sixfold. Distinct differences were noted in the response of the stressed seedlings toward exposure to Se or mimosine and included a decline in glutathione reductase (GR) activity by 50–60% in both mitochondria and soluble fractions of Se groups and an increase in GR activity of the mitochondria by twofold and of the soluble enzyme activity by 30% in the mimosine groups. Mimosine exposure resulted in a dose-dependent decrease in the γ-glutamyl transpeptidase levels, but, in contrast, a significant enhancement by 50% was noted in the Se group at 0.75 ppm. The results including the differential response of GR activity to Se or mimosine supplementation are reflective of an effective reductive environment in Se groups and increased turnover of GSH in the presence of mimosine.
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TL;DR: This review is to assess the mode of action and role of antioxidants in protecting plants from stress caused by the presence of heavy metals in the environment.
Abstract: The contamination of soils and water with metals has created a major environmental problem, leading to considerable losses in plant productivity and hazardous health effects. Exposure to toxic metals can intensify the production of reactive oxygen species (ROS), which are continuously produced in both unstressed and stressed plants cells. Some of the ROS species are highly toxic and must be detoxified by cellular stress responses, if the plant is to survive and grow. The aim of this review is to assess the mode of action and role of antioxidants in protecting plants from stress caused by the presence of heavy metals in the environment.
1,065 citations
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...A decline in GR activity by 50–60% was detected in both themitochondrial and soluble fractions of the Se-treated plants, while a 2-fold increase in GR activity in the mitochondria and 30% in the soluble fraction was detected in mimosine-treated plants (Santosh et al. 1999)....
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TL;DR: The results suggest that Se is an antioxidant or it activates protective mechanisms, which can alleviate oxidative stress in the chloroplasts, and improve the recovery of chlorophyll content following light stress.
Abstract: Higher plants are considered not to require selenium (Se). However, it has recently been shown that Se increases the antioxidative capacity and stress tolerance of lettuce (Lactuca sativa L.) and ryegrass (Lolium perenne L.). This research was undertaken to investigate the antioxidative properties of Se during photooxidative stress in potato (Solanum tuberosum L.) and to determine the defence mechanisms. Potato plants were exposed to 600 μmol/m2/s light intensity at low temperature (4 °C) or paraquat-mediated oxidative stress. The stress responses were monitored by measuring chlorophyll content and following changes in chlorophyll fluorescence and membrane ion leakage. Moreover, the effects of Se on the transcript levels of chloroplast CuZnSOD, mitochondrial MnSOD, glutathione peroxidase (GPX), and psbA were analyzed using northern hybridization. Se supplementation improved the recovery of chlorophyll content following light stress. After prolonged exposure to light, the reduction of Fv/Fm was slightly lower compared with plants cultivated without additional Se. The photosynthesis of Se treated plants was somewhat more tolerant of paraquat and the integrity of membranes was improved during oxidative stress. Se altered transcript accumulation of chloroplast CuZnSOD and GPX but the MnSOD and psbA transcript levels were unaffected. The results suggest that Se is an antioxidant or it activates protective mechanisms, which can alleviate oxidative stress in the chloroplasts.
209 citations
TL;DR: Although there was no change in total biomass, Se treatment was associated with a 43% increase in seed production and the Se-treated Brassica plants had higher total respiratory activity in leaves and flowers, which may have contributed to higher seed production.
Abstract: Selenium (Se) is essential for humans and animals but is not considered to be essential for higher plants. Although researchers have found increases in vegetative growth due to fertiliser Se, there has been no definitive evidence to date of increased reproductive capacity, in terms of seed production and seed viability. The aim of this study was to evaluate seed production and growth responses to a low dose of Se (as sodium selenite, added to solution culture) compared to very low-Se controls in fast-cycling Brassica rapa L. Although there was no change in total biomass, Se treatment was associated with a 43% increase in seed production. The Se-treated Brassica plants had higher total respiratory activity in leaves and flowers, which may have contributed to higher seed production. This study provides additional evidence for a beneficial role for Se in higher plants.
181 citations
TL;DR: This review attempts to appraise the literature related to non-protein amino acids, both in terms of their metabolism, plant–soil interactions and at the level of the ecosystem, where they are seen as significant drivers of structure and function.
Abstract: Non-protein amino acids are a significant store of organic nitrogen in many ecosystems, but there is a lack of knowledge relating to them. Research has indicated that they play important roles as metabolites, as allelopthic chemicals, in nutrient acquisition, in signalling and in stress response. They are also thought to be responsible for significant medical issues in both invertebrate and vertebrate animals. This review attempts to appraise the literature related to non-protein amino acids, both in terms of their metabolism, plant–soil interactions and at the level of the ecosystem, where they are seen as significant drivers of structure and function. Finally, important areas for future research are discussed.
120 citations
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...…growth factor Crounse et al. 1962; Hylin and Lichton 1965; Jones 1979; Ebuenga et al. 1979; Serrano et al. 1983; Sreekala et al. 1999; Santosh et al. 1999; Borthakur et al. 2003; Xuan et al. 2006; Andrade et al. 2009 3-aminopropionic acid -alanine Precursor, protection against stress…...
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TL;DR: An extra isoenzyme of glutathione reductase (GR) was induced in the presence of selenite, which confirmed the previous results obtained with Cd and Ni indicating that this GR isoenzymes may have the potential to be a marker for oxidative stress in coffee.
Abstract: Selenium (Se) is an essential element for humans and animals that is required for key antioxidant reactions, but can be toxic at high concentrations. We have investigated the effect of Se in the form of selenite on coffee cell suspension cultures over a 12-day period. The antioxidant defence systems were induced in coffee cells grown in the presence of 0.05 and 0.5 mm sodium selenite (Na2SeO3). Lipid peroxidation and alterations in antioxidant enzymes were the main responses observed, including a severe reduction in ascorbate peroxidase activity, even at 0.05 mm sodium selenite. Ten superoxide dismutase (SOD) isoenzymes were detected and the two major Mn-SOD isoenzymes (bands V and VI) responded more to 0.05 mm selenite. SOD band V exhibited a general decrease in activity after 12 h of treatment with 0.05 mm selenite, whereas band VI exhibited the opposite behavior and increased in activity. An extra isoenzyme of glutathione reductase (GR) was induced in the presence of selenite, which confirmed our previous results obtained with Cd and Ni indicating that this GR isoenzyme may have the potential to be a marker for oxidative stress in coffee.
99 citations
Cites background from "Oxidative stress during selenium de..."
...Studies with Trigonella foenun-graecum have shown a decline in GR activity by 50–60% in both the mitochondrial and soluble fractions of selenite-treated plants (Santosh et al. 1999)....
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...exhibited oxidative stress during Se deficiency and changes in the antioxidant enzyme activity, particularly of superoxide dismutase, catalase and peroxidase, in response to Se supplementation were identified (Santosh et al. 1999; Sreekala et al. 1999)....
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References
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TL;DR: Procedures are described for measuring protein in solution or after precipitation with acids or other agents, and for the determination of as little as 0.2 gamma of protein.
Abstract: Since 1922 when Wu proposed the use of the Folin phenol reagent for the measurement of proteins, a number of modified analytical procedures utilizing this reagent have been reported for the determination of proteins in serum, in antigen-antibody precipitates, and in insulin. Although the reagent would seem to be recommended by its great sensitivity and the simplicity of procedure possible with its use, it has not found great favor for general biochemical purposes. In the belief that this reagent, nevertheless, has considerable merit for certain application, but that its peculiarities and limitations need to be understood for its fullest exploitation, it has been studied with regard to effects of variations in pH, time of reaction, and concentration of reactants, permissible levels of reagents commonly used in handling proteins, and interfering substances. Procedures are described for measuring protein in solution or after precipitation with acids or other agents, and for the determination of as little as 0.2 gamma of protein.
289,852 citations
TL;DR: A water-soluble (at pH 8) aromatic disulfide [5,5′-dithiobis(2-nitrobenzoic acid] has been synthesized and shown to be useful for determination of sulfhydryl groups.
Abstract: A water-soluble (at pH 8) aromatic disulfide [5,5′-dithiobis(2-nitrobenzoic acid)] has been synthesized and shown to be useful for determination of sulfhydryl groups. Several applications have been made to show its usefulness for biological materials. A study of the reaction of this disulfide with blood has produced some evidence for the splitting of disulfide bonds by reduced heme.
23,232 citations
"Oxidative stress during selenium de..." refers methods in this paper
...Free thiol levels were measured by the procedure of Ellman ( 18 ) after deproteinization of the sample with metaphosphoric acid....
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TL;DR: In this article, the catalytic activity of catalase has been investigated using ultraviolet (UV) spectrophotometry and Titrimetric methods, which is suitable for comparative studies for large series of measurements.
Abstract: Publisher Summary Catalase exerts a dual function: (1) decomposition of H 2 O 2 to give H 2 O and O 2 (catalytic activity) and (2) oxidation of H donors, for example, methanol, ethanol, formic acid, phenols, with the consumption of 1 mol of peroxide (peroxide activity) The kinetics of catalase does not obey the normal pattern Measurements of enzyme activity at substrate saturation or determination of the K s is therefore impossible In contrast to reactions proceeding at substrate saturation, the enzymic decomposition of H 2 O 2 is a first-order reaction, the rate of which is always proportional to the peroxide concentration present Consequently, to avoid a rapid decrease in the initial rate of the reaction, the assay must be carried out with relatively low concentrations of H 2 O 2 (about 001 M) This chapter discusses the catalytic activity of catalase The method of choice for biological material, however, is ultraviolet (UV) spectrophotometry Titrimetric methods are suitable for comparative studies For large series of measurements, there are either simple screening tests, which give a quick indication of the approximative catalase activity, or automated methods
20,238 citations
TL;DR: The purification of homogeneous glutathione S-transferases B and C from rat liver is described, and only transferases A and C are immunologically related.
Abstract: The purification of homogeneous glutathione S-transferases B and C from rat liver is described. Kinetic and physical properties of these enzymes are compared with those of homogeneous transferases A and E. The letter designations for the transferases are based on the reverse order of elution from carboxymethylcellulose, the purification step in which the transferases are separated from each other. Transferase B was purified on the basis of its ability to conjugate iodomethane with glutathione, whereas transferase C was purified on the basis of conjugation with 1,2-dichloro-4-nitrobenzene. Although each of the four enzymes can be identified by its reactivity with specific substrates, all of the enzymes are active to differing degrees in the conjugation of glutathione with p-nitrobenzyl chloride. Assay conditions for a variety of substrates are included. All four glutathione transferases have a molecular weight of 45,000 and are dissociable into subunits of approximately 25,000 daltons. Despite the similar physical properties and overlapping substrate specificities of these enzymes, only transferases A and C are immunologically related.
16,953 citations
TL;DR: The staining procedure for localizing superoxide dismutase on polyacrylamide electrophoretograms has been applied to extracts obtained from a variety of sources and could thus be assayed either in crude extracts or in purified protein fractions.
Abstract: Nitro blue tetrazolium has been used to intercept O2− generated enzymically or photochemically. The reduction of NBT by O2− has been utilized as the basis of assays for superoxide dismutase, which exposes its presence by inhibiting the reduction of NBT. Superoxide dismutase could thus be assayed either in crude extracts or in purified protein fractions. The assays described are sensitive to ng/ml levels of super-oxide dismutase and were applicable in free solution or on polyacrylamide gels. The staining procedure for localizing superoxide dismutase on polyacrylamide electrophoretograms has been applied to extracts obtained from a variety of sources. E. coli has been found to contain two superoxide dismutases whereas bovine heart, brain, lung, and erthrocytes contain only one.
10,933 citations