Impact Of Se Research Articles

Biochemical and molecular responses of the ascorbate-glutathione cycle in wheat seedlings exposed to different forms of selenium

Biofortification aims to increase selenium (Se) concentration and bioavailability in edible parts of crops such as wheat (Triticum aestivum L.), resulting in increased concentration of Se in plants and/or soil. Higher Se concentrations can disturb protein structure and consequently influence glutathione (GSH) metabolism in plants which can affect antioxidative and other detoxification pathways. The aim of this study was to elucidate the impact of five different concentrations of selenate and selenite (0.4, 4, 20, 40 and 400 mg kg−1) on the ascorbate-glutathione cycle in wheat shoots and roots and to determine biochemical and molecular tissue-specific responses. Content of investigated metabolites, activities of detoxification enzymes and expression of their genes depended both on the chemical form and concentration of the applied Se, as well as on the type of plant tissue. The most pronounced changes in the expression level of genes involved in GSH metabolism were visible in wheat shoots at the highest concentrations of both forms of Se. Obtained results can serve as a basis for further research on Se toxicity and detoxification mechanisms in wheat. New insights into the Se impact on GSH metabolism could contribute to the further development of biofortification strategies.

Aryl selenonium vs. aryl sulfonium counterions in polyoxometalate chemistry: the impact of Se+ cationic centers on the photocatalytic reduction of dichromate.

A selenonium organic counter ion has been used in polyoxometalate chemistry to develop a new aryl selenonium polyoxometalate (POM) hybrid, and its photocatalytic properties have been explored in comparison with an aryl sulfonium POM-hybrid counterpart for the first time. The chalcogenonium counterions, namely, methyldiphenylsulfonium trifluoromethane sulfonate (MDPST) and methyldiphenylselenonium trifluoromethane sulfonate (MDPSeT), and their octamolybdate ([Mo8O26]4-) hybrids, 1 and 2, with the general formula (C13H13X)4[Mo8O26] (where X = S for 1 and Se for 2) were synthesized and characterized. Hybrids 1 and 2 vary in their chalcogenonium cationic center (S+vs. Se+), which enabled a direct comparison of their photocatalytic properties as a function of the cationic center. The photocatalytic activities of hybrids 1 and 2 were tested using the reduction of dichromate (Cr2O72-) as a model reaction under UV irradiation. A 99% photocatalytic reduction of Cr2O72- with a rate constant of 0.0305 min-1 was achieved with hybrid 2, while only a 67% reduction with a rate constant of 0.0062 min-1 was observed with hybrid 1 in 180 minutes. The better catalytic performance of hybrid 2 may be correlated to the larger atomic radii of Se than S, which helps in better stabilizing the photogenerated electron-hole (e--h+) pair on the POM cluster by polarizing its lone pair more efficiently compared to S. The catalytic recyclability was tested for up to 4 cycles using hybrid 2, and up to 98% reduction was obtained even after the 4th cycle. Recyclability tests and control experiments also indicated the generation of some elemental Se through possible cleavage of some C-Se bonds of MDPSe under prolonged UV exposure during catalysis, and the Se thus generated was found to contribute to the catalytic reduction of dichromate. This study, therefore, opens new avenues for aryl selenonium moieties and their POM hybrids for potential catalytic applications.

Impact of Se and Te addition on optical characteristics of ternary GeInSb chalcogenide films as promising materials for optoelectronic applications

The present study investigates the linear and non-linear optical characteristics of non-crystalline quaternary Ge15In5Sb5Se75 (GIS-Se) and Ge15In5Sb5Te75 (GIS-Te) chalcogenide thin films. The amorphous nature of the studied compositions was confirmed by x-ray diffraction (XRD). The values of transformation temperatures determined by differential thermal analysis (DTA), such as glass transition and crystallization temperatures, are 524.3 and 639.6 K for GIS-Se and 503.6 and 542.0 K for GIS-Te. The calculated values of glass forming ability () and thermal stability () for GIS-Se are higher than those for GIS-Te. The transmittance and reflectance spectrophotometric measurements in the UV–vis. wavelength range (400–2500 nm) are used to estimate the index of refraction and extinction coefficient The obtained values of and are found to be thickness independent in the investigated range. Tauc’s extrapolation model was used to determine both Urbach tail () and optical band gap () energies. The values of () are 0.416, 0.526 eV and () are 1.83, 1.31 eV with indirect allowed transitions for GIS-Se and GIS-Te, respectively. The optical conductivity increased as photon energy () increased, and it was enhanced in the presence of Te than Se addition. The analysis of the index of refraction () is used to evaluate the dispersion energy the high frequency dielectric constant the oscillator strength the lattice dielectric constant the ratio and the optical electronegativity which were found to be higher in GIS-Te than those in GIS-Se composition. The volume () and surface () energy loss functions were found to be increased with increasing () and the presence of Te. Furthermore, the calculated values of nonlinear optical susceptibility and nonlinear index of refraction for GIS-Se and GIS-Te are 0.195 × 10−12, 2.44 × 10−11 esu and 0.868 × 10−12, 10.19 × 10−11 esu, respectively. The detailed outcomes show that the studied film samples are suitable for various optical applications such as phase-change optical rewritable disks, optical sensors, optoelectronic devices and high-speed optical fibers.

Impact of Se in Structural, Mechanical, Thermal, Thermoelectric and Optical Properties of n-type SnTe

Lead-free SnTe compound is an alternative material for thermoelectric devices offering suitable band gap, non-toxicity, and mechanical stability. Here the structural, electronic, mechanical, thermal, thermoelectric, and optical properties of parent binary SnTe and ternary SnTe0.125Se0.875, SnTe0.25Se0.75, SnTe0.5Se0.5, SnTe0.75Se0.25, SnTe0.875Se0.125 materials are discussed at ambient conditions using full-potential linearized augmented plane wave method based on density functional theory. To make an accurate band gap we have used the mBJ scheme for the parent compound. The stability of the materials was confirmed using their calculated elastic constants. From the calculated mechanical properties, we have noted that the SnTe0.25Se0.75 material is more ductile and the SnTe0.875Se0.125 material has more hardness and a more brittle nature compared to other materials. We have computed the Seebeck coefficient, electrical conductivity, and power factor value in the temperature range of 300 to 1000 K in steps of 100 K using Boltzmann transport theory interfaced with the Wien2k program. From the thermoelectric properties, the ternary SnTe0.5Se0.5 havs a high power factor due to maximum electrical conductivity and is identified as a potential compound for thermoelectric applications. From the calculated optical results, the series of SnTe combinations are deemed suitable materials for optoelectronic applications. Our theoretical results are agreed well with available experimental results.

The Effect of Selenium- or Metal-Nanoparticles Incorporated Nanocomposites of Vinyl Triazole Based Polymers on Fungal Growth and Bactericidal Properties

Nano(Se, Ag, Au) capped with triazole-based polymers are promising nanomaterials for medicine and technique. Natural biopolymers are capable of exhibiting high efficiency in stabilization of metal/nonmetal nanoparticles. In this work, fungal extracellular polymers were found to contribute positively to the formation of hybrid polymeric element-containing nanocomposites and their biological activity. The impact of Se-, Ag-, or Au- nanocomposites chemically obtained in the matrix of homo- and co-polymer of vinyltriazole, on mushroom cultures with different taxonomic characteristics and growth conditions was studied. Enhanced mycelium growth caused by the nanocomposites implementation in the nutrient media was a prerequisite for making the Se-, Ag- or Au-containing polymeric agents based on the fungal extracellular metabolites. Sixty biopreparations thus obtained were screened for the bactericidal effect. Element-containing biocomposites suppressed the bacterial phytopathogens from the genera Micrococcus, Pectobacterium, Pseudomonas, Xanthomonas. Comparative studies of the chemically-and-biologically synthesized polymeric composites comprising selenium or metal nanoparticles would contribute to scientific foundations of manufacturing and implementing the innovative agents under question.

The Essential Role of Selenoproteins in the Resolution of Citrobacter rodentium-Induced Intestinal Inflammation.

Enteropathogenic Escherichia coli (EPEC) leads to adverse colonic inflammation associated with poor resolution of inflammation and loss of epithelial integrity. Micronutrient trace element selenium (Se) is incorporated into selenoproteins as the 21st amino acid, selenocysteine (Sec). Previous studies have shown that such an incorporation of Sec into the selenoproteome is key for the anti-inflammatory functions of Se in macrophages and other immune cells. An intriguing mechanism underlying the anti-inflammatory and pro-resolving effects of Se stems from the ability of selenoproteins to skew arachidonic acid metabolism from pro-inflammatory mediators, prostaglandin E2 (PGE2) toward anti-inflammatory mediators derived from PGD2, such as 15-deoxy-Δ12, 14- prostaglandin J2 (15d-PGJ2), via eicosanoid class switching of bioactive lipids. The impact of Se and such an eicosanoid-class switching mechanism was tested in an enteric infection model of gut inflammation by C. rodentium, a murine equivalent of EPEC. C57BL/6 mice deficient in Se (Se-D) experienced higher mortality when compared to those on Se adequate (0.08 ppm Se) and Se supplemented (0.4 ppm Se) diets following infection. Decreased survival was associated with decreased group 3 innate lymphoid cells (ILC3s) and T helper 17 (Th17) cells in colonic lamina propria of Se-D mice along with deceased expression of epithelial barrier protein Zo-1. Inhibition of metabolic inactivation of PGE2 by 15-prostaglandin dehydrogenase blocked the Se-dependent increase in ILC3 and Th17 cells in addition to reducing epithelial barrier integrity, as seen by increased systemic levels of FITC-dextran following oral administration; while 15d-PGJ2 administration in Se-D mice alleviated the effects by increasing ILC3 and Th17 cells. Mice lacking selenoproteins in monocyte/macrophages via the conditional deletion of the tRNA[Sec] showed increased mortality post infection. Our studies indicate a crucial role for dietary Se in the protection against inflammation following enteric infection via immune mechanisms involving epithelial barrier integrity.

Cadmium-induced oxidative stress promotes apoptosis and necrosis through the regulation of the miR-216a-PI3K/AKT axis in common carp lymphocytes and antagonized by selenium

Cadmium (Cd) is a primary environmental pollutant which causes the immune dysfunction of aquatic animals. MicroRNAs (miRNAs) play a key role in programmed necrosis and apoptosis of immune organs. Selenium (Se), known as an important element, can antagonize Cd toxicity in birds, but the impact of Se on common carps (Cyprinus carpio) has not been reported. To investigate the Cd-induced immunotoxicity mechanism mediated by miR-216a in splenic lymphocytes of common carp and antagonized by Se, we extracted lymphocytes from the spleen and divided them into control group, Se group (10−6 mol/L of Na2SeO3), Se + Cd group and Cd group (4 × 10−5 mol/L of CdCl2). After 6 h of incubation, AO/EB staining, Flow cytometry, qPCR and Western blot were performed. The results showed that Cd exposure caused the apoptosis (BAX, Bcl-2, Caspase 3, Caspase 9) and programmed necrosis (RIP, RIP3, MLKL) in lymphocytes, increased the expression of CYP enzymes, glycometabolism-related enzymes and production of ROS, while irritated the oxidative stress (MDA, SOD, CAT and GSH-PX), upregulated the expression of miR-216a which attenuated the levels of PI3K. However, those variations were apparently mitigated in the Se + Cd group. In short, we have proven that Cd activates oxidative stress and miR-216a-PI3K/AKT axis disorder, thus promoting apoptosis and necrosis in lymphocytes. Moreover, Se can antagonize Cd-triggered apoptosis and necrosis in lymphocytes.

Effect Of Selenium on Antioxidant Enzymes and Content of Photosynthetic Pigments in algae Chlorococcum littorale Chihara,Nakayama &Inouye

The study provides a new insight into the impact of Se on green algae Chlorocouyeoccum littorale and effects of Se on antioxidant system and bioaccumulation. Se positively promoted C. littorale growth at lower concentrations (≤50 mg L−1), acting as an antioxidant through the inhibition of lipid peroxidation (LPO) and intracellular reactive oxygen species (ROS). The antioxidative effect was associated with an increase in guaiacol peroxidase (GPX), catalase (CAT), superoxide dismutase (SOD) and photosynthetic pigments. Meanwhile, significant increase in the cell growth rate and organic Se content was also detected in the algae.

Selenium Uptake and Biotransformation and Effect of Selenium Exposure on the Essential and Trace Elements Status: Comparative Evaluation of Four Edible Plants

<p>Due to the essential nature of selenium and the beneficial effects attributed to the consumption of selenized plants in human and animal health. The accumulation, metabolism in plants and the effects of this element on the nutritional quality of exposed crops is still a subject of study. The selenium plant enrichment, in addition to providing dietary supplements with organic selenium species as SeMet and MeSeCys, could be a strategy to yield functional foods that guarantee the recommended absorption of other essential minerals. To contributing to the design of biofortification/supplementation strategies to obtain selenized edible sprouts, in this work were selected four types of plants commonly consumed in Mexico (radish, alfalfa, sunflower and chard), which were exposed to different concentrations of sodium selenite (0, 0.25, 0.5, 1.0, 5.0 and 10 mg of Se L-1) for 10 days. At the end of the exposure time, the growth, uptake and biotransformation from iSe to oSe, as well as the impact of Se on the content of other essential elements were evaluated. The results obtained indicate that alfalfa could be a good candidate to produce selenized food supplement, due to its short germination time (5 days), high yield of biomass production without growth inhibition up to selenite concentration corresponding to 10 mg L-1. Using this exposure condition, tSe accumulated in biomass is high (75.0 mg g-1) with 66% of iSe transformed to oSe in plant and with enhanced uptake of important minerals, namely Cu, Mn, Mo, Ca and K.</p>

Phenological application of selenium differentially improves growth, oxidative defense and ion homeostasis in maize under salinity stress

The underlying mechanism of selenium (Se) mediating plant salt tolerance is not well understood and information on how plant growth and development is regulated by phenological Se application (20 and 40 mg/L) under salinity stress is scarce. In present study, we have appraised the impact of phenological Se application on growth, antioxidant defense system and ionic imbalance in maize under salinity. Salinity (12 dS m−1) reduced growth, concentration of chlorophyll and K+ in root and leaf. Contrarily, salinity increased toxic Na+, malondialdehyde (MDA) and H2O2 concentration that resulted in oxidative damage. Lower level of Se application (20 mg/L) increased growth and chlorophyll by reducing oxidative damage due to high cell concentrations of MDA and H2O2. Se reduced endogenous levels of H2O2 and MDA under salinity. Moreover, Se regulated antioxidant defense system by increasing the activities of antioxidant enzymes (SOD, POD and CAT) and influenced the concentrations of non-enzymatic antioxidants (phenolics and flavonoids). Se-induced better antioxidant system protected plants from oxidative damage. We have also recorded substantial increase in K+ and decrease in Na+ concentration in plants treated with 20 mg/L Se under salinity stress. The impact of Se on plant growth and development is linked with the growth stage of exogenous application. Foliar Se at reproductive and both vegetative and reproductive stages improved salinity tolerance in maize compared with vegetative stage.

Selenium accelerates chicken dendritic cells differentiation and affects selenoproteins expression

Selenium (Se) promotes immune cell differentiation and improves immune response. Antigen-presenting cells such as dendritic cells (DCs) play an important role in immune system, however, the impact of Se on DCs is still unclear. In this study, we successfully induced and cultured chicken DCs from peripheral blood mononuclear cells by incubating mononuclear cells with 50 ng/mL recombinant chicken granulocyte-macrophage colony stimulating factor and 10 ng/mL recombinant chicken interleukin-4 for total 9 days. In + Se group, we added 10−7 mol/L sodium selenite from the first day of cell culture. The results showed that Se supplementation expedited and increased the expression of cell surface markers including CD11c, CD40, CD86, and MHC II. Principal component analysis showed that the expression of selenoproteins SelW, SelK, Dio3, GPX1, GPX2, SelN, SelS, SelH in chicken DCs was highly correlated, and SelW had highest correlation with the cell surface markers MHC II and CD11c. In conclusion, Se accelerates the differentiation and maturation of chicken DCs. Se regulates the differentiation and maturation of chicken DCs by selenoproteins. Selenoproteins has closely correlated to surface markers of chicken DCs.

Selenium increases hepatic DNA methylation and modulates one-carbon metabolism in the liver of mice

The average intake of the essential trace element selenium (Se) is below the recommendation in most European countries, possibly causing sub-optimal expression of selenoproteins. It is still unclear how a suboptimal Se status may affect health. To mimic this situation, mice were fed one of three physiologically relevant amounts of Se. We focused on the liver, the organ most sensitive to changes in the Se supply indicated by hepatic glutathione peroxidase activity. In addition, liver is the main organ for synthesis of methyl groups and glutathione via one-carbon metabolism. Accordingly, the impact of Se on global DNA methylation, methylation capacity, and gene expression was assessed. We observed higher global DNA methylation indicated by LINE1 methylation, and an increase of the methylation potential as indicated by higher S-adenosylmethionine (SAM)/S-adenosylhomocysteine (SAH) ratio and by elevated mRNA expression of serine hydroxymethyltransferase in both or either of the Se groups. Furthermore, increasing the Se supply resulted in higher plasma concentrations of triglycerides. Hepatic expression of glycolytic and lipogenic genes revealed consistent Se-dependent up-regulation of glucokinase. The sterol regulatory element-binding transcription factor 1 (Srebf1) was also up-regulated by Se. Both effects were confirmed in primary hepatocytes. In contrast to the overall Se-dependent increase of methylation capacity, the up-regulation of Srebf1 expression was paralleled by reduced local methylation of a specific CpG site within the Srebf1 gene. Thus, we provided evidence that Se-dependent effects on lipogenesis involve epigenetic mechanisms.

Se-methylselenocysteine inhibits apoptosis induced by clusterin knockdown in neuroblastoma N2a and SH-SY5Y cell lines.

Apoptosis, as a programmed cell death process, is essential for the maintenance of tissue function in organisms. Alteration of this process is linked to many diseases. Over-expression of clusterin (Clu) can antagonize apoptosis in various cells. Selenium (Se) is an essential trace element for human health. Its biological function is also associated with cell apoptosis. To explore the function of Clu and the impact of Se in the process of apoptosis, several short-hairpin RNAs (shRNA) were designed for the construction of two sets of recombinant plasmids: one set for plasmid-transfection of mouse neuroblastoma N2a cells (N2a cells); and the other set for lentiviral infection of human neuroblastoma SH-SY5Y cells (SH-SY5Y cells). These shRNAs specifically and efficiently interfered with the intracellular expression of Clu at both the mRNA and protein levels. The Clu-knockdown cells showed apoptosis-related features, including down-regulation of antioxidative capacity and the Bcl-2/Bax ratio and up-regulation of caspase-8 activity. Se-methylselenocysteine (MSC) at an optimum concentration of 1 μM could reverse the alteration in antioxidative capacity, Bcl2/Bax ratio and caspase-8 activity caused by Clu-knockdown, thus inhibiting apoptosis and maintaining cell viability. The results hereby imply the potentiality of Clu and Se in neuroprotection.

Does Nursing Student Self-efficacy Correlate with Knowledge When Using Human Patient Simulation?

BackgroundSelf-efficacy (SE) is commonly believed to be associated with nursing knowledge and is thought to be improved with manikin-based human patient simulation (HPS) training. Yet there is little evidence of a relationship between SE and knowledge. MethodsUsing a 2-group (HPS and control) experimental design, we examined the relationship of knowledge and SE and the predictors of knowledge scores in 161 students (age 25.7 ± 6.6; 89% female) from 4 prelicensure cohorts at three nursing schools. Knowledge and SE assessments were given at two testing points: Baseline and after HPS. Statistical analyses consisted of Pearson's correlations, analysis of variance, and multivariate logistic regression with the covariates of group (HPS or control), gender, ethnicity, SE and knowledge at baseline, school, and number of prior HPS exposure(s). ResultsSignificant score increases in SE and knowledge were seen between the testing points for the experimental group (had HPS), but not the control group (no HPS) and differences were found between the groups for both variables (p < .01 for each). However, there was no correlation between SE and knowledge. Additionally, a logistic regression for “high” SE scores revealed baseline SE (p ≤ .01) and HPS participation (p = .002) as the only predictors of higher SE scores. Furthermore, SE was not a predictor of “good” knowledge scores. ConclusionThis study demonstrated SE and knowledge gains in subjects who participated in HPS; however, there was no correlation between SE and knowledge nor was SE a predictor of “good” knowledge scores. Although educators strive to develop SE in their students, the limitations of SE's impact on outcome measures such as knowledge needs to be established.

Influence of selenium (Se) on carbohydrate metabolism, nodulation and growth in alfalfa (Medicago sativa L.)

Background and Aims Selenium (Se) is an essential micronutrient for humans and animals, but its role in plants remains unclear. Selenium enters the food chain via crops, and thus, plants constitute an essential source of Se in human nutrition. As a N2-fixing plant of high nutritive value, alfalfa (Medicago sativa L.) is an important forage legume for sustainable agriculture. This study investigated the effects of Se on carbohydrate metabolism, nodulation and growth in alfalfa. In addition, the impact of Se on fructose 1,6-bisphosphatase (F1,6-BPase), a key enzyme in carbohydrate metabolism, as well as on nitrogenase activity in N-metabolism was examined.

Abstract 1896: Selenium and isothiocyanates increases TrxR1 and GI-GPx expression but DNA methylation of LINE-1 remains unchanged in Caco-2 cells

Abstract Currently, there is significant interest in the field of diet-gene interactions and the mechanisms by which food compounds regulate gene expression through epigenetic events to modify cancer susceptibility. Evidence from epidemiological, in vivo and in vitro studies have suggested that the chemopreventive effect of cruciferous vegetables is attributed to the glucosinolate break-down products, isothiocyanates (ITCs). Similarly, selenium (Se) is an integral part of many cellular antioxidant enzymes and like isothiocyanates has been inversely associated with the incidence of cancer as a result of influencing multiple pathways in the development of cancer. However, their efficacy might depend on the chemical form in which they are administered. We therefore examined the synergistic effect of two forms of selenium, selenium-methylselenocysteine (Se-MSC) and selenite (200nM) with ITCs (6µM) such as iberin and sulforaphane on the expression of antioxidant selenoenzymes such as thioredoxin-reductase (TrxR1) and gastrointestinal glutathione peroxidise (GI-GPx) in an in vitro model using Caco-2 cells. Our preliminary results suggest that the simultaneous addition of Se-MSC and iberin significantly induced TrxR1 and GI-GPx mRNA and protein expression more than either compound alone by ∼6 fold (p&amp;lt;0.001). In addition to the antioxidant protection provided by these selenoproteins, DNA methylation is essential for normal development, but aberrant DNA methylation patterns are a hallmark of most cancers and include global DNA hypomethylation, region-specific hypermethylation and increased DNA methyltransferases (DNMTs) activity. We therefore also examined the impact of Se and ITCs on DNA methylation, specifically examining factors modulating DNMT1, 3A, 3B expression and methylation of the LINE-1 retrotransposon, a surrogate marker of global DNA methylation. Caco-2 cells were treated with Se-MSC and selenite using 0.2, 0.5, 1, 2 and 5µM, in addition to the ITCs (6µM) after 5 and 10 days of treatment. Our initial data suggests that methylation of LINE-1 in the control group was indeed low (55%) and treatment of cells with DNMT inhibitor 5-aza-2 deoxycytidine resulted in a 45% reduction in LINE-1 methylation as expected. Unexpectedly, none of the food compounds or dose used in this study modified significantly the methylation status of LINE-1. Interestingly, although the methylation levels of this marker remain unchanged, the mRNA expression of the DNMTs showed the tendency to decrease, following the same pattern in the different treatments and time courses albeit with small differences, which suggests that both de novo and maintenance DNMTs work in concert to create and propagate methylation patterns. However, only DNMT3B showed a significant reduction of 35 and 38% after 10 days of treatment with Se-MSC (500nM) (p=0.04) and selenite (1µM) (p=0.035) respectively. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1896.