Interactive Effects Of Selenium Research Articles

Interactive Effects of Selenium and Arsenic on their Accumulation, Translocation, Arsenic and Selenium Species, and Subcellular Distribution in Brassica Vegetables

Interactive Effects of Selenium and Arsenic on their Accumulation, Translocation, Arsenic and Selenium Species, and Subcellular Distribution in Brassica Vegetables

Interactive effects of selenium and arsenic on phenolic constituents and antioxidant activity in rice (Oryza sativa L.)

Arsenic (As) is a heavy toxic metalloid found in air, water and soil that adversely affects the plant growth by inducing oxidative stress in plants. Its contamination of rice is a serious problem throughout the world. Selenium (Se) is a beneficial micronutrient for plants that acts as an antioxidant at low doses and protect the plants against number of environmental stresses either by modulating the primary metabolic pathways or regulating the production of phenolic compounds. In the present investigation, effect of Se on different phenolics, enzymes related to their metabolism and antioxidative potential were studied in As stressed rice leaves. Rice plants were grown in pots containing sodium arsenate (2–10 mg As(V) kg−1 soil) and sodium selenate (0.5–1 mg Se kg−1 soil), both alone and in combination and leaf samples were analyzed for various biochemical parameters. Phenolic constituents increased in rice leaves with As(V) treatment from 2 to 5 mg kg−1 soil and leaves exposed to As(V) @ 5 mg kg−1 soil exhibited 1.7, 1.9 and 2.5 fold increase in total phenolics, o-dihydroxyphenols and flavonols, respectively at grain filling stage. Binary application of Se + As improved various phenolic constituents, FRAP, reducing power and antioxidant activities as compared to control. PAL, TAL and PPO activities increased from 1.3 to 4.6 fold in combined As + Se treatment at both the stages. Anthocyanin contents showed a decline (10.8 fold) with increasing As doses and its content improved at both the stages with maximum increase of 3.76 fold with As5+Se1 combination. Binary application of As + Se improved gallic acid, chlorogenic acid, 3-hydroxy benzoic acid and kaempferol contents than control whereas catechin and coumaric acid showed the reverse trend. Application of Se can modulate phenolic constituents in leaf and grains of rice Cv PR126 due to As stress that helped plants to adapt to excess As and resulted in improved plant growth.

Interactive effects of selenium and arsenic on growth, antioxidant system, arsenic and selenium species of Nicotiana tabacum L.

This paper is aimed to study separate and interactive effects of selenium (Se) (selenite, 0–5mgL−1) and arsenic (As) (arsenate, 0–5mgL−1) on the growth and the antioxidant system of flue-cured tobacco (FCT) as well as the contents and species of As and Se in FCT through a hydroponic experiment and clarify the possible mechanism how Se alleviates the toxicity of As. The results were: single addition of Se (≤1mgL−1) or As (1mgL−1) by a low dose could stimulate the growth of FCT, but the growth of FCT would be inhibited when Se (5mgL−1) or As (5mgL−1) was added by a high dose. Low As levels stimulated the uptake of Se but high levels of As posing the opposite effects with the low Se dosage. However, the addition of As always inhibited the uptake of Se with high Se levels. Moreover, Se showed dual effects on the uptake of As. At the low As dose (1mgL−1), the addition of Se inhibited the growth of FCT, but significantly promoted the activity of superoxide dismutase (SOD) and peroxidase (POD) enzymes as well as the content of MDA. Meanwhile, the percentages of organic Se and As(III) in the leaves of FCT declined with the increasing Se dose. However, the addition of Se by a moderate dose (0.1mgL−1) alleviated the toxicity of the high As dose (5mgL−1) and promoted the growth of FCT by elevating the ability of anti-oxidative stress of FCT and reducing the contents of MDA and As in FCT. The Se species in the leaves of FCT existed in organic ones (SeCys and SeMet) (100%), while the major As speciation was As(III) (75%). Likewise, the addition of As counteracted the toxicity of high Se dose (5mgL−1) and promoted the growth of FCT slightly as it reduced the formation of organic Se or failed to transform excess inorganic Se species into organic ones and depressed the contents of Se in the roots and leaves of FCT. In a word, the low Se dose (0.1mgL−1) alleviated of the toxicity of the high As dose and the addition of As counteracted the toxicity of high Se dose (5mgL−1), as a result of which the promotion of the growth of FCT were realized.

Co-exposure Effects of Selenium and Mercury on Phaseolus vulgaris Excised Leaves Segment by Enhancing the NR, Anti-oxidative Enzyme Activity and Detoxification Mechanisms

Mercury is known to disrupt the biological function in plants by inhibiting their growth and developmental process, while selenium (Se) is an essential micronutrient within the appropriate amount. This paper is aimed to study co application and interactive effects of selenium (Se) and mercury (Hg) on the Nitrate Reductase NR (such as in-vivo and endogenous) and the antioxidant system through a pot experiment and clarify the possible mechanism how Se alleviates the toxicity of Hg. The observations indicate that when selenium applied after mercury exposure the enzyme activity enhanced hence Se may reduce the toxic level of Hg in phaseolus vulgaris.

Interactive Effects of Selenium and Mercury on Their Uptake by Rice Sedlings

In this study, a new modeling method based on metasynthesis is proposed from the macro and micro levels. And the system analysis and design agent-oriented based on POMDP are provided in the same time. Finally, the two case studies are given and the experimental results have shown efficiency and rationality of this modeling method. Under greenhouse conditions, rice was taken as test object and the interactive effects of selenium and mercury in rice seedlings grown in solution culture were researched by the use of quadratic-orthogonal-rotation-combination design. The results showed that low mercury concentration (<30 μg/L) promoted selenium absorption in rice roots and shoots, which may be associated with selenium’s favorable effect on plant. Higher mercury concentration (>30 μg/ L) reduced selenium accumulation in rice roots and stems, as well as the transfer of selenium to the rice shoot. When the mercury concentration was fixed at 100 μg/L, Se in the growth medium significantly reduced Hg accumulation in the roots and the effect of Se on Hg accumulation in shoots displayed a similar pattern. However, with the increase of selenium concentration of the solution, the Hg transfer coefficient from the root to the shoot remained unchanged.

Interactive effects of selenium and antimony on the uptake of selenium, antimony and essential elements in paddy-rice

Aims Selenium (Se) can be used to detoxify antimony (Sb); however, the associated mechanisms are not fully understood, in particular, the responses of essential elements to co-exposure to Se and Sb.

Interactive effects of selenium and arsenic on their uptake by Pteris vittata L. under hydroponic conditions

The interactive effects of selenium (Se) and arsenic (As) on plant uptake of Se and As have rarely been documented. In this study, the interactive effects of As and Se on their uptake by Chinese brake fern ( Pteris vittata), an As-hyperaccumulator and Se-accumulator, were explored in two hydroponic experiments based on a two-factor, five-level central composite design. At Se levels of less than 2.5 mg L −1, increasing amounts of As stimulated the uptake of Se in Chinese brake fern roots, possibly because of the beneficial effects of Se. In contrast, at Se concentrations greater than 2.5 mg L −1, As suppressed the uptake of Se in Chinese brake fern roots. Uptake of As by both fronds and roots of Chinese brake fern was suppressed by the addition of Se, indicating the antagonistic effects of Se on As. In addition, at Se concentrations of less than 2.5 mg L −1, As stimulated the translocation of Se from roots to fronds; meanwhile, the addition of Se resulted in reduced translocation of As from roots to fronds. These findings demonstrate the interactive effects of As and Se on their uptake by Chinese brake fern.

Interactive Effects of Selenium and Cadmium on Mammary Tumor Development and Growth in MMTV-Infected Female Mice. A Model Study on the Roles of Cadmium and Selenium in Human Breast Cancer

Previous studies demonstrated that the age-corrected breast cancer mortalities in different countries are inversely correlated with the per-capita dietary intakes of selenium and directly with the estimated intakes of cadmium, zinc, and chromium, suggesting that the anticarcinogenic properties of selenium are counteracted by these elements. The tumor-preventative effects of selenium and the converse effects zinc and chromium have already been confirmed experimentally in studies with female inbred C3H mice carrying murine mammary tumor virus (MMTV). Using the same model of human breast cancer, it is now demonstrated that cadmium abolishes the cancer-protecting effects of selenium. In addition, cadmium was also found to interact with zinc, copper, and chromium. At 1.4 ppm in the drinking water, cadmium caused a significant depletion of zinc in vital organs such as the liver, which is held responsible for a delay of the appearance of the mammary tumors by 4 months and their slower growth rates relative to the Cd-unexposed controls. The results of the present study are relevant to human breast cancer prevention as selenium counteracts the effects of cadmium.

Interactive Effects of Selenium and Chromium on Mammary Tumor Development and Growth in MMTV-Infected Female Mice and Their Relevance to Human Cancer

Evidence for interactive effects of chromium and selenium on the appearance of mammary tumors was obtained by exposing female virgin C3H mice infected with the murine mammary tumorvirus (MMTV) to subtoxic levels of Cr [as Cr(III) nitrate] and Se (as sodium selenite) in the supply water. Cr counteracted the inhibitory effect of Se on tumor development in a dose-dependent manner, shortened the tumor latency period, and accelerated tumor growth rates. Exposure to Cr also altered the levels of Se in the liver and kidneys of the mice, indicating that Cr interacts with Se and affects its organ distribution. Chromium must be added to the list of Se-antagonistic elements that weaken or abolish the antitumorigenic effects of Se. These findings are relevant to human cancer as previous studies revealed the age-corrected mortalities from breast and other major forms of cancer in different countries to be inversely correlated with the dietary Se intakes, and directly correlated with the estimated intakes of Cr and of other Se-antagonistic elements. The presence of these elements in foods must be taken into account when estimating the optimal dose of supplemental Se for cancer risk reduction.

Interactive effects of selenium and mercury on the restoration potential of leaves of the medicinal plant, Portulaca oleracea Linn

Leaves of Portulaca oleracea have the potential of regeneration, when grown in a distilled water medium. The two heavy metals, Se and Hg individually and in combination affected both shoot and root development. They completely arrested shoot development at all concentrations. However, they produced concentration-dependent changes in the development of roots, which ranged from their complete inhibition to variation in their initiation time, number and length. Leaf decay was initiated on day 46 in control leaves. Concentration-dependent changes were also observed in the time of initiation and magnitude of decay of leaves. The data indicates that Hg was more toxic than Se. The protective effect of Se against Hg toxicity was evident only at very low concentrations. With further increases in the concentration of both Se and Hg, the protective effect decreased and simultaneously the toxicity increased. Following the decay of leaves, a pink colour development was observed only on leaves exposed to Se. Microbial analysis of leaves showed the presence of Acinetobacter only in Se-exposed leaves. Acinetobacter was therefore considered as probably involved in the formation of elemental Se, which produced a pink colour. © 1998 Elsevier Science B.V. All rights reserved.

Interactive effects of selenium, methionine, and dietary protein on survival, growth, and physiology in mallard ducklings.

Concentrations of over 100 ppm (100 mg/kg) selenium (Se) have been found in aquatic food chains associated with irrigation drainwater. Both quantity and composition of dietary protein for wild ducklings may vary in selenium-contaminated environments. Day-old mallard (Anas platyrhynchos) ducklings received one of the following diets containing 22% protein: unsupplemented (controls), 15 ppm Se (as selenomethionine), 60 ppm Se, methionine supplemented, 15 ppm Se with methionine supplement, or 60 ppm Se with methionine supplement. In a second concurrent experiment the above sequence was repeated with a protein-restricted (11%) but isocaloric diet. In a third concurrent experiment all ducklings received 44% protein with 0, 15, or 60 ppm Se added. After 4 weeks, blood and tissue samples were collected for biochemical and histological examination. With 22% protein and 60 ppm Se in the diet, duckling survival and growth was reduced and histopathological lesions of the liver occurred. Antagonistic interactive effects occurred between supplementary methionine and Se, including complete to partial alleviation of the following Se effects by methionine: mortality, hepatic lesions, and altered glutathione and thiol status. With 11% protein, growth of controls was less than that with 22% protein, Se (60 ppm) caused 100% mortality, and methionine supplementation, although protective afforded less protection than it did with 22% protein. With 44% protein, ducklings experienced physiological stress, and Se was more toxic than with methionine-supplemented 22% protein. These findings suggest the potential for antagonistic effects of Se, methionine, and protein on duckling survival and physiology.

Influence of dietary fat and selenium in initiation and promotion of aflatoxin B1-induced preneoplastic foci in rat liver.

Aflatoxin B1-induced hepatic gamma-glutamyl transpeptidase-positive foci were quantified in rats fed different levels of fat and selenium during either initiation or early promotion. Male Sprague-Dawley rats were divided into 12 groups. One of six experimental diets were fed to groups 1-6 prior to and during aflatoxin B1 exposure (initiation, weeks 1-4.5) and to groups 7-12 during weeks 4.5-15 (promotion). The six experimental diets contained 2 or 20% corn oil, each with either less than 0.02, 0.15 or 2.5 (or 1.9) p.p.m. selenium. When not fed the experimental diets, rats were fed a modified AIN-76A diet. In groups 1-6, 0.03% phenobarbital was added as a promoter to the AIN-76A diet. Individual and interactive effects of selenium and fat were dependent on the stage of carcinogenesis. High dietary fat fed with either less than 0.02 or 0.15 p.p.m. selenium during initiation resulted in a significant increase in the number and size of foci when compared with low fat groups. In rats fed 20% fat and 2.5 p.p.m. selenium during initiation, preneoplastic development was reduced below all low fat groups. In contrast, selenium status but not dietary fat level influenced focal formation during promotion. Rats fed less than 0.02 p.p.m. selenium had a significantly greater percentage of liver section occupied by foci than rats fed either 0.15 or 1.9 p.p.m. selenium. Feeding 1.9 p.p.m. selenium during promotion did not afford greater protection above the 0.15 p.p.m. level. Hepatic glutathione peroxidase activity at week 15 was significantly diminished in animals fed less than 0.02 p.p.m. selenium during promotion. Feeding 1.9 p.p.m. selenium when compared with 0.15 p.p.m. did not result in a consistent increase in enzyme activity. Although differences were observed in growth due to dietary treatment, there were no significant correlations between preneoplastic foci and body weight, food consumption or food efficiency. These findings indicate an interaction between dietary fat and selenium during initiation, but not during early promotion. Furthermore, dietary selenium and fat may function by different mechanisms at different stages of carcinogenesis.