Concentrations Of Selenium In Medium Research Articles

Accumulation of selenium and catalase activity changes in the cells ofSaccharomyces cerevisiae on pulsed electric field (PEF) treatment

The aim of this work is the evaluation of selenium accumulation and catalase activity in pulsed electric field (PEF) treatedSaccharomyces cerevisiae cells. Cultures ofS. cerevisiae in the medium containing selenium as sodium selenite were treated with PEF. Applied range of field parameters (field frequency of 1 Hz, intensity of 1.5 kV/cm and pulse duration of 1 ms) does not influence the changes of catalase activity which depend only on the concentration of selenium accumulated in the yeast cells. It was noted for the non-PEF-treated cultures that the accumulation of selenium in the yeast cells increased to 60 μg/g dry mass (DM) together with the increase of selenium concentration in medium from 1 to 3 μg/mL. Consequently, the activity of extra- and intra-cellular catalase also increased. At higher selenium concentrations in medium (4–6 ug/mL) its accumulation in the cells reached 127 μg/g DM which resulted in the decrease of catalase activity. In the PEF-treated cultures, twofold higher accumulation of selenium in the cells was obtained in the whole rang e of concentrations applied, which caused the significant decrease of catalase activity.

Ukrainian dietary bakery product with selenium-enriched yeast

Bread is a most important food product and source of selenium in Ukraine. However, low content of selenium in wheat flour from north and northwest regions of Ukraine does not ensure the recommended consumption of selenium. Daily intake of selenium by the population of North Ukraine is below recommended allowance. The aim of this research was to study the production of the dietary rolls with selenium-enriched yeast for the population of North Ukraine. The study showed that to obtain bakery yeast of good quality, concentration of sodium hydroselenite in the medium for yeast cultivation should be in the range from 2 to 5 μg Se/ml. Under these concentrations of selenium in medium, specific growth rate and biomass yield as well as bakery properties of the yeast Saccharomyces cerevisiae did not differ from the parameters of yeast, grown in the medium without selenium. Maturation of the selenium-enriched yeast improved their bakery properties. The 100 g wheat roll prepared with selenium-enriched yeast contained 50 μg Se (25% of the recommended daily allowance) in the form of selenomethionine, which is the best form of selenium for human consumption. These rolls can be used as a dietary product to reach recommended daily consumption of selenium by the population of North Ukraine and Chernobyl region.

Significance of selenium-labeled proteins for selenium's chemopreventive functions.

A 58 kDa selenium-labeled protein purified from mouse mammary epithelial cells (MMEC) was used to examine whether selenium modulates protein synthesis or is just a marker for cellular selenium status. The protein was isolated using Sephadex G150 gel filtration and DEAE-Sephadex A50 ion-exchange chromatography. It was further analysed using 2-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and was found as a single spot with a pI of 4.6. The immunoreactivity with anti-58 kDa antiserum and the 75Se signal co-localized on a single 58 kDa protein band on both 1D- and 2D-PAGE. Partial amino acid analysis of the peptide showed homology with the thiol protein disulfide oxidoreductase (TPDO). Varying the selenium concentration in culture medium did not affect the protein content or the immunoreactivity of the 58 kDa protein. Additionally, selenium did not seem to regulate the activity of TPDO in TM6 cells. The glutathione peroxidase activity of TM6 cells, taken as the internal positive control, was enhanced with the increase in selenium concentration in the medium. The results suggest that selenium is attached to the 58 kDa protein, but does not regulate either its protein synthesis or its functional activity. We conclude that selenium labeling of the 58 kDa protein reflects the cellular selenium status but probably is not involved in its chemopreventive ability.