Initial Step of Selenite Reduction via Thioredoxin for Bacterial Selenoprotein Biosynthesis.

Many organisms reductively assimilate selenite to synthesize selenoprotein. Although the thioredoxin system, consisting of thioredoxin 1 (TrxA) and thioredoxin reductase with NADPH, can reduce selenite and is considered to facilitate selenite assimilation, the detailed mechanism remains obscure. Here, we show that selenite was reduced by the thioredoxin system from Pseudomonas stutzeri only in the presence of the TrxA (PsTrxA), and this system was specific to selenite among the oxyanions examined. Mutational analysis revealed that Cys33 and Cys36 residues in PsTrxA are important for selenite reduction. Free thiol-labeling assays suggested that Cys33 is more reactive than Cys36. Mass spectrometry analysis suggested that PsTrxA reduces selenite via PsTrxA-SeO intermediate formation. Furthermore, an in vivo formate dehydrogenase activity assay in Escherichia coli with a gene disruption suggested that TrxA is important for selenoprotein biosynthesis. The introduction of PsTrxA complemented the effects of TrxA disruption in E. coli cells, only when PsTrxA contained Cys33 and Cys36. Based on these results, we proposed the early steps of the link between selenite and selenoprotein biosynthesis via the formation of TrxA-selenium complexes.

Profiling of selenium and other trace elements in breads from rice and maize cultivated in a seleniferous area of Punjab (India).

The objective of the study was to assess selenium and other elements levels in Indian Roti bread from Se-rich maize and rice using inductively coupled plasma mass-spectrometry. Se levels in Roti bread from Se-rich maize and rice exceeded those in the control samples by a factor of more than 594 and 156, respectively. Using Se-enriched maize increased bread Co, Cr, Mn, Mo, and Zn content, whereas Fe and I levels were reduced. In Se-rich rice-based bread a decrease in Co, Cr, Cu, Fe, I, Mo, and Zn contents was observed. Daily consumption of Se-rich maize and rice bread (100 g) could account for 5.665% and 4.309% from recommended dietary allowance, also exceeding the upper tolerable levels by a factor of 7.8 and 5.9, respectively. Therefore, Roti bread from both Se-rich maize and rice may be considered as an additional source of selenium. At the same time, regular intake of Se-rich grains and its products including breads may cause adverse health effects even after a few days and should be regularly monitored in order to prevent Se overload and toxicity.

Integrating genome-wide association study summaries and element-gene interaction datasets identified multiple associations between elements and complex diseases.

Chemical elements are closely related to human health. Extensive genomic profile data of complex diseases offer us a good opportunity to systemically investigate the relationships between elements and complex diseases/traits. In this study, we applied gene set enrichment analysis (GSEA) approach to detect the associations between elements and complex diseases/traits though integrating element-gene interaction datasets and genome-wide association study (GWAS) data of complex diseases/traits. To illustrate the performance of GSEA, the element-gene interaction datasets of 24 elements were extracted from the comparative toxicogenomics database (CTD). GWAS summary datasets of 24 complex diseases or traits were downloaded from the dbGaP or GEFOS websites. We observed significant associations between 7 elements and 13 complex diseases or traits (all false discovery rate (FDR) < 0.05), including reported relationships such as aluminum vs. Alzheimer's disease (FDR = 0.042), calcium vs. bone mineral density (FDR = 0.031), magnesium vs. systemic lupus erythematosus (FDR = 0.012) as well as novel associations, such as nickel vs. hypertriglyceridemia (FDR = 0.002) and bipolar disorder (FDR = 0.027). Our study results are consistent with previous biological studies, supporting the good performance of GSEA. Our analyzing results based on GSEA framework provide novel clues for discovering causal relationships between elements and complex diseases.

Correlation of Serum Selenium in Asthma Patients with Severity of the Disorder.

Asthma is characterized by reversible airway obstruction, increased bronchial hyper-responsiveness and chronic inflammation, as well as higher levels of oxidative stress mainly due to decreased antioxidant defenses. Our primary aim was to investigate the correlation of serum selenium (Se) levels with the severity of asthma across gender, age, family history, and prevalence from childhood. Selenium levels in blood samples in 103 asthmatic patients and 103 healthy individuals were evaluated. The obtained data indicated that the mean serum Se levels in asthma patients were found to be twofold lower as compared to the controls (p < 0.001). However, there were no significant differences in the asthmatic patients when gender and age were considered. Patients characterized by family history of asthma and inhaler usage had 8% and 7% lower serum Se concentrations, although the difference was only border significant (p = 0.05). Multiple regression analysis demonstrated a significant inverse association of inhaler usage (ß = - 0.226; p < 0.001) with serum Se levels even after adjustment for asthma severity (ß = - 0.644; p < 0.001). While this report clearly necessitates a more detailed study, it is plausible that Se deficiency leads to impaired immune response, and therefore, Se supplementation might modulate oxidative stress in the lung and could potentially alleviate asthma pathophysiology.

Complete Genome Sequence of Pseudomonas stutzeri Strain F2a, Isolated from Seleniferous Soil.

Pseudomonas stutzeri is a potential candidate for bioremediation of selenium-contaminated grounds and waters. Here, we report the complete genome sequence of a novel strain, F2a, which was isolated from a seleniferous area of Punjab, India. The genome sequence provides insight into the potential selenium oxyanion-reducing activity of this strain.

Removal of selenium from Se enriched natural soils by a consortium of Bacillus isolates.

Four bacterial strains designated as SNTP-1, NS-2 to NS-4 were isolated from selenium contaminated soils of Nawanshahr-Hoshiarpur region of Punjab, India, by enrichment technique and a consortium was developed using these isolates. The isolates were observed to be belonging to Bacillus sp. In soil microcosm, complete removal was observed by the consortium in selenite augmented soils while the rate of removal with consortia in selenate treatment was 72% after 120 days. Population survival of isolates showed stability at lower treatments and decline at higher levels of Se enrichment. The consortium can, thus, be used for removal of Se contaminated sites.

Selenium and Other Elements in Wheat (Triticum aestivum) and Wheat Bread from a Seleniferous Area.

The objective of the present study was to assess the levels of Se, as well as other essential and toxic trace elements in wheat grains and traditional Roti-bread from whole-grain flour in a seleniferous area of Punjab (India) using inductively-coupled plasma mass-spectrometry. Wheat grain and bread selenium levels originating from seleniferous areas exceeded the control values by a factor of more than 488 and 179, respectively. Se-rich wheat was also characterized by significantly increased Cu and Mn levels. Se-rich bread also contained significantly higher levels of Cr, Cu, I, Mn, and V. The level of Li and Sr was reduced in both Se-enriched wheat and bread samples. Roti bread from Se-enriched wheat was also characterized by elevated Al, Cd, and Ni, as well as reduced As and Hg content as compared to the respective control values. Se intake with Se-rich bread was estimated as more than 13,600% of RDA. Daily intake of Mn with both Se-unfortified and Se-fortified bread was 133% and 190% of RDA. Therefore, Se-rich bread from wheat cultivated on a seleniferous area of Punjab (India) may be considered as a potent source of selenium, although Se status should be monitored throughout dietary intervention.

Selenium-rich mushrooms cultivation on a wheat straw substrate from seleniferous area in Punjab, India.

Intensive rice-wheat cultivation cycle in Northern belt of India in general and in the State of Punjab in particular results in large volumes of straw and other post-harvest residue annually. The agricultural area, bordering the districts of Nawanshahr and Hoshiarpur, is popularly known as the seleniferous belt of India. The agri-residues, generated in seleniferous region of this state, are observed to contain significantly high concentration of selenium (Se). The present study was aimed to evaluate the Se uptake by different mushroom species: Pleurotus sajor-caju, Pleurotus ostreatus, Pleurotus citrinopileatus, Agaricus bisporus, and Volvariella volvacea, cultivated on Se-rich wheat and paddy straw from the seleniferous region. Wheat (Pleurotus species and A. bisporus) and paddy straw (V. volvacea) was inoculated with the mycelium spawn and left for 7-20 days, depending on the species, to grow. Control mushrooms were grown analogously using the agricultural residues from non-seleniferous area of the State of Punjab. All fruiting bodies were collected and analyzed in triplicate. Se was quantified using inductively coupled plasma sector field mass spectrometry. The Se accumulation was high in all species under study, being the highest in A. bisporus (1396 µg/g vs. 46.8 µg/g in controls - dry weight) and V. volvacea (231 µg/g vs. 3.77 µg/g - dry weight). The observed biological efficiency and total yield for all mushroom species showed good and unaltered productivity in Se-rich conditions, if compared to the controls. The Se-rich mushrooms can be prospective Se-supplements sourcing and biofortified foods, providing readily bioavailable and accessible Se for the diets deficient of this biologically essential element.

The Level of Toxic Elements in Edible Crops from Seleniferous Area (Punjab, India).

The primary objective of the present study was to assess the level of selenium and toxic trace elements in wheat, rice, maize, and mustard from seleniferous areas of Punjab, India. The content of selenium (Se) and toxic trace elements, including aluminum (Al), arsenic (As), cadmium (Cd), mercury (Hg), nickel (Ni), lead (Pb), and tin (Sn), in crop samples was assessed using inductively coupled plasma mass-spectrometry after microwave digestion of the samples. The obtained data demonstrate that cultivation of crops on seleniferous soils significantly increased Se level in wheat, mustard, rice, and maize by a factor of more than 590, 111, 85, and 64, respectively. The study also showed that Se exposure affected toxic metal content in crops. In particular, Se-rich wheat was characterized by a significant decrease in Al, As, Ni, Pb, and Sn levels. The level of As, Cd, Ni, Pb, and Sn was significantly decreased in Se-rich rice, whereas As content was increased. In turn, the decrease in Al, As, Cd, Ni, Pb, and Sn levels in Se-rich maize was associated with a significant elevation of Hg content. Finally, Se-rich mustard was characterized by a significant increase in Al, As, and Hg levels, while the content of Ni, Pb, and Sn was significantly lower than the control levels. These findings should be taken into account while developing the nutritional strategies for correction of Se status. At the same time, the exact mechanisms underlying the observed differences are to be estimated.

Imbalance of dietary nutrients and the associated differentially expressed genes and pathways may play important roles in juvenile Kashin-Beck disease.

BACKGROUND: Kashin-Beck disease (KBD) is a childhood-onset endemic osteoarthropathy in China. Nutrients including trace elements may play active roles in the development of KBD. OBJECTIVE: This study aimed to estimate the nutrient intakes of children in endemic areas and to identify the imbalanced nutrients associated differentially expressed genes in the juvenile patients with KBD. METHODS: In this cross-sectional study, a consecutive 3 day 24 h semi-quantitative dietary retrospect questionnaire was conducted to estimate the daily nutrient intakes of children using CDGSS 3.0 software. Gene profile analysis was employed to identify differentially expressed genes in peripheral blood mononuclear cells of children with KBD. GOC, CTD, KEGG, and REACTOME databases were used to establish the relationship between nutrients and nutrients-associated differentially expressed genes and pathways. Statistical analyses were accomplished by SPSS 18.0 software. RESULTS: Daily Se intakes without supplementation of children were significantly lower in Se-supplemented (Se + ) KBD areas (29.3 ∼ 29.6 mg/d) and non-endemic area (27.8 ±â€¯7.9 mg/d) compared to non-Se-supplemented (Se-) KBD area (32.9 ±â€¯7.9 mg/d, c2 = 20.24, P < .01). Children in Se+ KBD areas were suffering more serious insufficient intake of multiple nutrients, including vitamins-B2/-C/-E, Ca, Fe, Zn and I. Gene profile analysis combined with bioinformatics technique identified 34 nutrients associated differentially expressed genes and 10 significant pathways which are related to the pathological changes in juvenile KBD. CONCLUSIONS: Imbalance of dietary nutrients and nutrients-associated differentially expressed genes and pathways may play important roles in the development of juvenile KBD.

Selenium supplementation through Se-rich dietary matrices can upregulate the anti-inflammatory responses in lipopolysaccharide-stimulated murine macrophages.

The accessibility of selenium from naturally enriched sources such as cereals crops can potentially be used as selenium supplements to support nutritional requirements. Dietary selenium supplementation, as Se-rich wheat extracts, on RAW264.7 macrophage cells enhanced the antioxidant capacity via augmentation of cellular selenoprotein glutathione peroxidase 1 (GPx-1) expression in the absence or presence of lipopolysaccharide (LPS) treatment. Cells were supplemented with Se in the form of sodium selenite (SS), seleniferous wheat extract (SeW) and seleniferous wheat extract with rMETase treatment (SeW+rMET) at three different concentrations. Cells supplemented with SS and SeW+rMET showed increase in GPx-1 expression as compared to SeW treated cells. SeW+rMET, further, down-regulated the LPS-induced expression of cyclooxygenase-2, microsomal PGE synthase-1 and inducible nitric oxide synthase w.r.t. Se-deficient cells, while the expression of hematopoietic PGD synthase was upregulated. This demonstrates SeSup effectively modulates the expression inflammatory responses, indicating the potential benefits of dietary selenium supplementation.

Selenium uptake by edible oyster mushrooms (Pleurotus sp.) from selenium-hyperaccumulated wheat straw.

In an effort to produce selenium (Se)-fortifying edible mushrooms, five species of oyster mushroom (Pleurotus sp.), were cultivated on Se-rich wheat straw collected from a seleniferous belt of Punjab, India. Total selenium was analyzed in the selenium hyperaccumulated wheat straw and the fruiting bodies. Significantly high levels (p<0.0001) of Se uptake were observed in fruiting bodies of all mushrooms grown on Se-rich wheat straw. To the best of our knowledge, accumulation and quantification of selenium in mushrooms has hitherto not been reported with substrates naturally enriched with selenium. The results demonstrate the potential of selenium-rich agricultural residues as substrates for production of Se-enriched mushrooms and the ability of different species of oyster mushrooms to absorb and fortify selenium. The study envisages potential use of selenium-rich agricultural residues towards cultivation of Se-enriched mushrooms for application in selenium supplementation or neutraceutical preparations.

Transesterification of triglycerides by dried biomass of Aspergillus sp.

Fungus isolate, Aspergillus sp. (RBD01), which was isolated from biocontaminated clarified butter was evaluated for its potential to transesterify used edible and non-edible oils for generation of alkyl esters, when used as biocatalyst as dry biomass. The work aimed at determining the potential of dry biomass of Aspergillus sp. (RBD01) to transesterify used cottonseed oil and non-edible oils viz., jatropha and karanj under various culture conditions. A conversion of oil (cotton seed) to ethyl ester to the extent of 84% was obtained at reaction temperature of 35°C, with 20% biomass and step-wise addition of ethanol at 1:5 molar ratio (oil to ethanol), within total reaction time of 36 h. Under similar conditions, transesterification of Jatropha and Karanj oils resulted in only 75 and 78.2% ethyl ester. Further, with reference to the effect of frying on transesterification, increase in frying time decreased the extent of transesterification from 84% to 30%.