Topic
Selenium
About: Selenium is a research topic. Over the lifetime, 21192 publications have been published within this topic receiving 429715 citations. The topic is also known as: Se & selen.
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TL;DR: The large predominance of selenomethionine in local wheat shows that local wheat can be a promising raw material for naturally enriched products to be used to supplement human and animal diets in low selenium areas.
Abstract: Wheat (Triticum aestivum) collected in the Nawanshahr-Hoshiarpur Region (Punjab, India) showed the highest selenium concentrations ever recorded in cereal grains (29−185 μg g−1). There was a strong positive relationship between the selenium content in shoots and that in kernels, showing that grain selenium concentration can be predicted from that in the vegetative tissues of the plant. The identity and content of the selenocompounds in the grain samples and in wheat-based reference materials were investigated by HPLC−ICP−dynamic reaction cell−MS. Reversed-phase, cation exchange, and anion exchange HPLC were used to separate the selenium species after ultrasound-assisted enzymatic extraction with an ultrasonic probe. Selenomethionine and selenate accounted for 72−85% and 2−6% of the sum of the selenium species, respectively. The proportion of organic Se species varied with increasing Se content; namely, SeMet showed a relative reduction whereas the other organoselenium compounds increased up to 18−22% of t...
121 citations
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TL;DR: A selenite-respiring bacterium, Bacillus selenitireducens, produced significant levels of Se(-II) (as aqueous HSe−) when supplied with Se(0), while no such activity was noted in formalin-killed controls as mentioned in this paper.
Abstract: A selenite-respiring bacterium, Bacillus selenitireducens, produced significant levels of Se(-II) (as aqueous HSe−) when supplied with Se(0). B. selenitireducens was also able to reduce selenite [Se(IV)] through Se(0) to Se(-II). Reduction of Se(0) by B. selenitireducens was more rapid in cells grown on colloidal sulfur [S(0)] or Se(IV) as their electron acceptor than for cell lines grown on fumarate. In contrast, three cultures of selenate-respiring bacteria, Sulfurospirillum barnesii, B. arsenicoselenatis, and Selenihalanaerobacter shriftii either were unable to reduce Se(0) to Se(-II) or had only a very limited capacity to achieve this reduction. Biological reduction of Se(0) to Se(-II) was observed during incubation of estuarine sediment slurries, while no such activity was noted in formalin-killed controls. The majority of the Se(-II) produced was found in the sediments as a solid precipitate of FeSe, rather than in solution as HSe−. These results demonstrate that certain anaerobic bacteria have the ...
121 citations
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121 citations
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TL;DR: The proposed methodology was used to study qualitative and quantitative speciation of selenium in human serum samples from healthy volunteers and patients on haemodialysis.
Abstract: A post-column isotope dilution analysis (IDA) methodology has been applied to carry out the quantitative speciation of selenium in human serum by affinity chromatography coupled to inductively coupled plasma mass spectrometry (ICP-MS) with an octapole reaction system (ORS). The interfering argon dimers on the 78Se and 80Se isotopes were suppressed by pressurizing the octapole chamber with hydrogen. The separation of the selenium-containing proteins was evaluated both by anion exchange chromatography (Mono Q HR 5/5) and affinity chromatography (Hi-Trap Heparin- and Hi-Trap Blue-Sepharose columns). Quantification of selenium was performed by post-column isotope dilution analysis by continuous mixing of an enriched 77Se spike solution with the eluent from the column. Finally, the 78Se/77Se or 80Se/77Se isotope ratios were monitored and the amount of selenium bound to proteins was evaluated. The chromatographic separation of selenium-containing proteins in human serum by anion exchange chromatography was not satisfactory. On the other hand, the use of affinity chromatography allowed for a rapid, precise and convenient fractionation of those proteins. Three main selenium fractions could be separated and quantified: selenoprotein P, albumin and glutathione peroxidase. Mass balance performed under different experimental conditions showed quantitative selenium recovery. The proposed methodology was used to study qualitative and quantitative speciation of selenium in human serum samples from healthy volunteers and patients on haemodialysis. The distribution of selenium between plasma glutathione peroxidase (∼20%), selenoprotein P (∼55%) and albumin (∼20%) was similar in both populations.
121 citations