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.

Selenium biofortification and antioxidant activity in lettuce plants fed with selenate and selenite

Abstract: Selenium is an important element associated with enhancement of antioxidant activity in plants, microorganisms, animals, and humans. In Brazil, the information on Se in agricultural crops is lacking, though there are indications that low levels of Se are consumed by the population. The experiment was conducted under greenhouse conditions with pots containing 3 l of nutritive solution in a completely randomized factorial design, with seven Se concentrations (0, 2, 4, 8, 16, 32, and 64 µmol/l) and two forms of Se (sodium selenate – Na 2 SeO 4 and sodium selenite – Na 2 SeO 3 ), with six replicates. The application of Se as selenate at low concentrations is more appropriate for let tuce biofortification because it favors shoot biomass growth and Se levels in the shoot biomass. Selenium in both forms had two effects on lettuce plant metabolism: at low doses it acted as an antioxidant and enhanced plant growth, whereas at higher levels it reduced yield.

Delayed formation of zero-valent selenium nanoparticles by Bacillus mycoides SeITE01 as a consequence of selenite reduction under aerobic conditions

Abstract: Background: Selenite (SeO3 2� ) oxyanion shows severe toxicity to biota. Different bacterial strains exist that are capable of reducing SeO3 2� to non-toxic elemental selenium (Se 0 ), with the formation of Se nanoparticles (SeNPs). These SeNPs might be exploited for technological applications due to their physico-chemical and biological characteristics. The present paper discusses the reduction of selenite to SeNPs by a strain of Bacillus sp., SeITE01, isolated from the rhizosphere of the Se-hyperaccumulator legume Astragalus bisulcatus. Results: Use of 16S rRNA and GyrB gene sequence analysis positioned SeITE01 phylogenetically close to B. mycoides .O n agarized medium, this strain showed rhizoid growth whilst, in liquid cultures, it was capable of reducing 0.5 and 2.0 mM SeO3 2� within 12 and 24 hours, respectively. The resultant Se 0 aggregated to form nanoparticles and the amount of Se 0 measured was equivalent to the amount of selenium originally added as selenite to the growth medium. A delay of more than 24 hours was observed between the depletion of SeO3 2 and the detection of SeNPs. Nearly spherical-shaped SeNPs were mostly found in the extracellular environment whilst rarely in the cytoplasmic compartment. Size of SeNPs ranged from 50 to 400 nm in diameter, with dimensions greatly influenced by the incubation times. Different SeITE01 protein fractions were assayed for SeO3 2� reductase capability, revealing that enzymatic activity was mainly associated with the membrane fraction. Reduction of SeO3 2� was also detected in the supernatant of bacterial cultures upon NADH addition.

Biogenic Synthesis of Selenium Nanoparticles and Their Effect on As(III)-Induced Toxicity on Human Lymphocytes

Abstract: A bioreductive capacity of a plant, Terminalia arjuna leaf extract, was utilized for preparation of selenium nanoparticles. The leaf extract worked as good capping as well as stabilizing agent and facilitated the formation of stable colloidal nanoparticles. Resulting nanoparticles were characterized using UV-Vis spectrophotometer, transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDAX), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction analysis (XRD), respectively. The colloidal solution showed the absorption maximum at 390 nm while TEM and selected area electron diffraction (SAED) indicated the formation of polydispersed, crystalline selenium nanoparticles of size raging from 10 to 80 nm. FT-IR analysis suggested the involvement of O-H, N-H, C=O, and C-O functional group of the leaf extract in particle formation while EDAX analysis indicated the presence of selenium in synthesized nanoparticles. The effect of nanoparticles on human lymphocytes treated with arsenite, As(III), has been studied. Studies on cell viability using MTT assay and DNA damage using comet assay revealed that synthesized selenium nanoparticles showed protective effect against As(III)-induced cell death and DNA damage. Chronic ingestion of arsenic infested groundwater, and prevalence of arsenicosis is a serious public health issue. The synthesized benign nanoselenium can be a promising agent to check the chronic toxicity caused due to arsenic exposure.