Selenium is one of the elements classified within the group of micronutrients which are necessary in trace amounts for the proper functioning of organisms. Selenium participates in the protection of ...cells against excess H₂O₂, in heavy metal detoxification, and regulation of the immune and reproductive systems as well. It also ensures the proper functioning of the thyroid gland. Selenium induces the occurrence of the selenoprotein synthesis process involved in the antioxidant defense mechanism of the organism. Recent years have brought much success in the studies on selenium. Anticarcinogenic properties of selenium against some cancers have been reported. Supplementation is increasingly becoming a solution to this problem. A large number of different supplementation methods are promoting studies in this area. Slight differences in the selenium content can result in excess or deficiency, therefore supplementation has to be done carefully and cautiously.
The fungi
Aureobasidium pullulans
,
Mortierella humilis
,
Trichoderma harzianum and Phoma glomerata
were used to investigate the formation of selenium- and tellurium-containing nanoparticles during ...growth on selenium- and tellurium-containing media. Most organisms were able to grow on both selenium- and tellurium-containing media at concentrations of 1 mM resulting in extensive precipitation of elemental selenium and tellurium on fungal surfaces as observed by the red and black colour changes. Red or black deposits were confirmed as elemental selenium and tellurium, respectively. Selenium oxide and tellurium oxide were also found after growth of
Trichoderma harzianum
with 1 mM selenite and tellurite as well as the formation of elemental selenium and tellurium. The hyphal matrix provided nucleation sites for metalloid deposition with extracellular protein and extracellular polymeric substances localizing the resultant Se or Te nanoparticles. These findings are relevant to remedial treatments for selenium and tellurium and to novel approaches for selenium and tellurium biorecovery.
The present experiment aimed to compare toxic effects of dietary organic or inorganic selenium (Se) and to predict of Se intake and tissue Se concentrations in broiler chickens based on feather Se ...concentrations. A total of four hundred twenty 7-day-old Ross 308 male broiler chicks were allotted to 1 of 7 dietary treatments in a completely randomized design. Each treatment had 6 replicates with 10 birds per replicate. Organic Se (selenium yeast) or inorganic Se (sodium selenite) was added to the basal diet at the levels of 5, 10, or 15 mg/kg Se. All experimental diets were fed to birds on an ad libitum basis for 28 d. Results indicated that a significant interaction (P < 0.01) was observed between Se sources and inclusion levels for the BW gain and feed intake of broiler chickens with inorganic Se at 15 mg/kg in diets showing a greatest negative effect. Increasing inclusion levels of Se in diets increased (linear, P < 0.01) plasma concentrations of uric acid. Increasing inclusion levels of Se in diets increased (linear, P < 0.01) relative liver weight. No significant interactions were observed between Se sources and inclusion levels in diets on hepatic antioxidant capacity. Increasing inclusion levels of Se in diets increased (linear, P < 0.01) Se concentrations in the liver, breast, and feather. The concentrations of Se in the breast, liver, and feather were greater (P < 0.05) for organic Se than for inorganic Se in diets. The toxic levels of organic or inorganic Se in broiler diets were near 7 or 9 mg/kg based on the BW gain, respectively. The prediction equations indicate that feather Se concentrations in broiler chickens can be used to predict both daily Se intake and Se concentrations in the liver and breast.
Selenium, Selenoproteins, and Immunity Avery, Joseph C; Hoffmann, Peter R
Nutrients,
2018-Sep-01, 2018-09-01, 20180901, Volume:
10, Issue:
9
Journal Article
Peer reviewed
Open access
Selenium is an essential micronutrient that plays a crucial role in development and a wide variety of physiological processes including effect immune responses. The immune system relies on adequate ...dietary selenium intake and this nutrient exerts its biological effects mostly through its incorporation into selenoproteins. The selenoproteome contains 25 members in humans that exhibit a wide variety of functions. The development of high-throughput omic approaches and novel bioinformatics tools has led to new insights regarding the effects of selenium and selenoproteins in human immuno-biology. Equally important are the innovative experimental systems that have emerged to interrogate molecular mechanisms underlying those effects. This review presents a summary of the current understanding of the role of selenium and selenoproteins in regulating immune cell functions and how dysregulation of these processes may lead to inflammation or immune-related diseases.
Traditional supplements of selenium generally have a low degree of absorption and increased toxicity. Therefore, it is imperative to develop innovative systems as transporters of selenium compounds, ...which would raise the bioavailability of this element and allow its controlled release in the organism. Nanoscale selenium has attracted a great interest as a food additive especially in individuals with selenium deficiency, but also as a therapeutic agent without significant side effects in medicine. This review is focused on the incorporation of nanotechnological applications, in particular exploring the possibilities of a more effective way of administration, especially in selenium-deficient organisms. In addition, this review summarizes the survey of knowledge on selenium nanoparticles, their biological effects in the organism, advantages, absorption mechanisms, and nanotechnological applications for peroral administration.
In the recent decade, growing efforts have been devoted to employing elemental selenium as a selenium source in organic synthesis. In contrast to unstable, smelly, and toxic previous selenium ...reagents, elemental selenium is readily available, cheap, bench‐stable, and easy to handle. This review will mainly focus on the strategies for the activation of elemental selenium and the synthesis of organoselenium compounds including monoselenides, diselenides, selenium‐containing heterocycles and so on.
Selenium (Se³⁴₇₉) is a metalloid which is close to sulfur (S) in terms of properties. The Se concentration in soil varies with type, texture and organic matter content of the soil and with rainfall. ...Its assimilation by plants is influenced by the physico-chemical properties of the soil (redox status, pH and microbial activity). The presence of Se in the atmosphere is linked to natural and anthropogenic activities. Selenoproteins, in which selenium is present as selenocysteine, present an important role in many body functions, such as antioxidant defense and the formation of thyroid hormones. Some selenoprotein metabolites play a role in cancer prevention. In the immune system, selenium stimulates antibody formation and activity of helper T cells, cytotoxic T cells and Natural Killer (NK) cells. The mechanisms of intestinal absorption of selenium differ depending on the chemical form of the element. Selenium is mainly absorbed in the duodenum and caecum by active transport through a sodium pump. The recommended daily intake of selenium varies from 60 μg/day for women, to 70 μg/day for men. In growing ruminants the requirements are estimated at 100 μg/kg dry matter and 200 μg/Kg for pregnant or lactating females. A deficiency can cause reproductive disorders in humans and animals.
Selenium (Se) is an essential trace element unevenly distributed on the Earth's crust with low selenium regions predominating. To prevent selenium-deficiency diseases in livestock, additions of ...selenium to animal feed are required and were approved for all species, but the chemical form of the element to be added was not specified. Presently, sodium selenite is still widely employed, although it is not a natural nutritional form of selenium. Its use creates ecological problems and affects human selenium nutriture in as much as the meat, milk, and eggs from animals maintained on selenite contain less selenium than from animals receiving it as selenomethionine, the chief natural nutritional form of the element present in grain crops grown in selenium-adequate regions, or from high-selenium yeast added to feedstock.
Human dietary selenium intakes are sub-optimal in many countries but are considered to be adequate if they reach the currently adopted Recommended Dietary Allowances (RDAs). Their upward revision will be required if the health benefits of selenium are to be fully utilized.
During the last decades, the perception of selenium has undergone substantial changes. While its toxic effects were recognized causing hair and hoof loss in animals during the 1930s, its essential ...role in microbial, animal and human metabolism has been recognized later, i.e. with the discovery of selenium deficiency causing “white muscle disease” in feedstock in the 1950s. Nowadays, the positive effect of systematic selenium supplementation is discussed in manifold topics such as cancer or diabetes prevention and avian influenza susceptibility. Treatment of selenium containing waste streams poses a notable challenge to environmental engineers, and to date no ultimate solution has been found for e.g. the selenium contamination in agricultural areas of the western USA. For the future, selenium contamination carries an imminent danger, if the increasing energy demand is covered by fossil fuel combustion, which will lead to major selenium emission and toxicity. This review presents current knowledge of selenium’s role in environmental sciences and outlines potentially feasible treatment options targeting a variety of selenium contaminated waste streams.
•The delay of spraying stage decreased the proportions of organic Se and protein Se in brown rice.•The proportions of organic Se and protein Se in brown rice showed no differences between selenite ...and selenate treatments.•Foliar spray of Se contributes to a relatively high conversion of Se to organic and protein forms in rice grains.
Foliar spray of selenium (Se) has increasingly been applied to improve Se concentrations in crops. There is a lack of systematic and in-depth study comparing the effects of foliar spray with different Se sources at different growth stages. In this study, selenite or selenate (75g Se ha−1) was sprayed to the foliage of rice plants at the late tillering or full heading stage. Se concentrations in different parts of rice plants were determined to assess the effects of foliar spray with different Se sources at different growth stages on Se distribution in the plant, Se metabolism in the grains, and Se recovery efficiency in the brown rice. At the same spraying stages, total Se, organic Se, and protein Se concentrations in brown rice obtained with selenate were ∼2-fold those obtained with selenite. With the same Se sources, total Se, organic Se, and protein Se concentrations in brown rice treated at full heading were 2-fold higher than those treated at late tillering. The delay of spraying stage decreased the distribution ratio of Se in straw and roots, while it increased the distribution ratio of Se in grain; this trend was more evident with selenate. The proportions of organic Se and protein Se in brown rice showed no differences between selenite and selenate treatments at the same stages. The delay of spraying stage decreased the proportions of organic Se and protein Se in brown rice (still up to 80% and 44%, respectively), whereas the recovery efficiency of Se was improved in brown rice by more than 1-fold. In conclusion, appropriately delaying the spraying stage and selecting selenate as the Se source can be more efficient for producing Se-enriched rice.
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