Search results for "Selenium"
showing 10 items of 178 documents
Food and Environment: Trace Element Content of Hen Eggs from Different Housing Types
2013
AbstractEleven trace elements (Ba, Cu, Fe, Mn, Ni, Pb, Rb, Se, Sr, V, Zn) were quantitatively determined in hen egg samples collected from different poultry housing types (large-scale poultry farms, organic farms and domestic farms) over the territory of Latvia. Samples were wet digested and quantitatively analysed by total reflection X-ray fluorescence spectrometry (TXRF). The accuracy of analytical method was verified with analysis of certified reference material NCS ZC73017 (GSB-10)-Apple. The most variable range of concentrations and the highest content of elements were determined for hen egg samples derived from organic farms, while egg samples from domestic farms and poultry farms mos…
Mercury and selenium in fish and shellfish: Occurrence, bioaccessibility and uptake by Caco-2 cells
2012
This study evaluates Hg and Se concentrations and bioaccessibility (element solubilised after simulated gastrointestinal digestion) in 16 raw seafood species consumed in Spain. The concentrations varied greatly (Hg, 3.8-1621 ng/g wet weight, ww; Se, 84-1817 ng/g ww). Only one sample of swordfish exceeded the Hg limit permitted in Spain (1mg/kg), and for this sample the Hg/Se molar ratio and Se Health Benefit Value food safety criteria also indicated the presence of a risk. Bioaccessibility of Hg (35-106%) and Se (17-125%) was very variable and the Hg/Se molar ratio in the bioaccessible fraction was less than one for all samples. Transport by Caco-2 cells, an intestinal epithelium model, was…
Characterization of a novel selenium methyltransferase from freshwater bacteria showing strong similarities with the calicheamicin methyltransferase
2004
A novel group of Se-methyltransferases is presented. The genetic determinant, named mmtA, which revealed this group was isolated from selenite and selenate-resistant freshwater bacteria. E. coli expressing mmtA and grown with a Se supplement emitted dimethyl selenide (DMSe) and dimethyl diselenide (DMDSe). Phylogenetic analysis divided MmtA-like bacterial sequences into two clusters, one grouping MmtA with S- and O-methyltransferases, and one grouping UbiE C-methyltransferases. Se methylation by some of these MmtA phyletic neighbours was investigated.
Beneficial Effect of Two Culture Systems with Small Groups of Embryos on the Development and Quality of In Vitro-Produced Bovine Embryos
2014
Summary Currently, in vitro-produced embryos derived by ovum pick up (OPU) and in vitro fertilization (IVF) technologies represent approximately one-third of the embryos worldwide in cattle. Nevertheless, the culture of small groups of embryos from an individual egg donor is an issue that OPU-IVF laboratories have to face. In this work, we tested whether the development and quality of the preimplantation embryos in vitro cultured in low numbers (five embryos) could be improved by the addition of epidermal growth factor, insulin, transferrin and selenium (EGF-ITS) or by the WOW system. With this aim, immature oocytes recovered from slaughtered heifers were in vitro matured and in vitro ferti…
Assimilation of Selenium, Copper, and Zinc in Rye Malt
2018
Abstract Trace elements selenium, copper, and zinc are essential minerals for the human body. One of the means to increase the micronutrient content in diets is to add them to food raw materials, for example, to enrich grain with micronutrients during malt production. To obtain rye malt, 3 kg grain was soaked in 10 l water with addition of three mineral salts — sodium selenate (Na2SeO4), copper sulphate (CuSO4 5H2O), and zinc sulphate (ZnSO4 7H2O) at different concentrations and different combination of salts. The concentration of selenium, copper, and zinc was determined in rye malt. The obtained results were used to calculate the degree of assimilation of trace elements in rye malt. The i…
Influence of bacterial physiology on processing of selenite, biogenesis of nanomaterials and their thermodynamic stability
2019
We explored how Ochrobactrum sp. MPV1 can convert up to 2.5 mM selenite within 120 h, surviving the challenge posed by high oxyanion concentrations. The data show that thiol-based biotic chemical reaction(s) occur upon bacterial exposure to low selenite concentrations, whereas enzymatic systems account for oxyanion removal when 2 mM oxyanion is exceeded. The selenite bioprocessing produces selenium nanomaterials, whose size and morphology depend on the bacterial physiology. Selenium nanoparticles were always produced by MPV1 cells, featuring an average diameter ranging between 90 and 140 nm, which we conclude constitutes the thermodynamic stability range for these nanostructures. Alternativ…
PIXE ANALYSES OF THE SOLUBLE AND MEMBRANE SE-CONTAINING PROTEINS EXTRACTED FROMCUPRIAVIDUS METALLIDURANSCH34 AFTER SELENIUM OXIDES CHALLENGE
2008
The soil bacterium Cupriavidus metallidurans CH34 resist selenite by reducing it into the insoluble and less toxic elemental selenium. Two mechanisms of reduction of selenium oxides in C. metallidurans CH34 were highlighted: assimilation leading to organic species and detoxification leading to precipitation of selenite in nanoparticules of elemental selenium. The alkyl selenide detected as an intermediate product during assimilation of selenite or as the major accumulated chemical form during assimilation of selenate was identified as selenomethionine.Soluble and membrane proteins were extracted from C. metallidurans CH34 submitted to selenium oxides challenge. After separation by SDS-PAGE,…
Isotope Fractionation of Selenium During Fungal Biomethylation by Alternaria alternata
2011
The natural abundance of stable Se isotopes may reflect sources and formation conditions of methylated Se. We aimed at (1) quantifying the degree of methylation of selenate [Se(VI)] and (hydro)selenite [Se(IV)] by the fungus Alternaria alternata at pH 4 and 7 and (2) determining the effects of these different Se sources and pH values on 82Se/76Se ratios (δ82/76Se) in methylselenides. Alternaria alternata was incubated with Se(VI) and Se(IV) in closed microcosms for 11-15 days and additionally with Se(IV) for 3-5 days at 30 °C. We determined Se concentrations and δ82/76Se values in source Se(VI) and Se(IV), media, fungi, and trapped methylselenides. In Se(VI) incubations, methylselenide vola…
Selenium: A Cure for Autoimmune Thyroiditis.
2021
Autoimmune thyroiditis (AT) is a disease whose incidence has increased dramatically over the past few decades. In iodine sufficient areas, this pathological condition affects up to 5% of the general population. The higher incidence of AT observed in areas of the world with low-selenium (Se) soils apperas to be the consequence of a reduced activity of the intracellular Sedependent glutathione peroxidase activity. Se is involved, through selenoproteins, in the regulation of intracellular antioxidant, redox and anti-inflammatory processes. As a component of selenoproteins, Se exerts various structural and enzymatic functions. A low Se/high fat diet can cause selenoprotein changes and promote t…