A new organic selenium compound, 2-hydroxy-4-methylselenobutanoic acid (SeO), displayed a greater bioavailability than sodium selenite (SeNa) or seleno-yeast (SeY) in several species.
This study ...sought to determine the regulation of the speciation of selenium, expression of selenogenome and selenocysteine biosynthesis and degradation-related genes, and production of selenoproteins by the 3 forms of selenium in the tissues of broiler chicks.
Day-old male chicks (
= 6 cages/diet, 6 chicks/cage) were fed a selenium-deficient, corn and soy-based diet base diet (BD), 0.05 mg Se/kg or the BD + SeNa, SeY, or SeO at 0.2 mg Se/kg for 6 wk. Plasma, livers, and pectoral and thigh muscles were collected at weeks 3 and 6 to assay for total selenium, selenomethionine, selenocysteine, redox status, and selected genes, proteins, and enzymes.
Although both SeY and SeO produced greater concentrations (
< 0.05) of total selenium (20-172%) and of selenomethionine (≤15-fold) in the liver, pectoral muscle, and thigh than those of SeNa, SeO further raised (
< 0.05) these concentrations by 13-37% and 43-87%, respectively, compared with SeY. Compared with the BD, only SeO enhanced (
0.05) the mRNA of
(
)
and
(
) in the liver and thigh (62-98%) and thioredoxin reductase (TXRND) activity in the pectoral and thigh muscles (20-37%) at week 3. Furthermore, SeO increased (
0.05) the expression of
(
)
, GPX4, SELENOP, and SELENOU relative to the SeNa group by 26-207%, and the expression of
, GPX4, and SELENOP relative to the SeY group by 23-55% in various tissues.
Compared with SeNa or SeY, SeO demonstrated a unique ability to enrich selenomethionine and total selenium depositions, to induce the early expression of
and
mRNA and TXRND activity, and to enhance the protein production of GPX4, SELENOP, and SELENOU in the tissues of chicks.
Chagas disease is one of the most prevalent tropical neglected diseases and causes high mortality and morbidity in endemic countries. Current treatments for this disease, nifurtimox and benznidazole, ...are ineffective in the chronic phase of the disease and produce severe adverse effects. Therefore, novel therapies are urgently required. The trace element selenium has an important role in human health, due to its antioxidant, antiinflammatory and pro-immune properties. Actually, its deficiency has been related to several diseases and supplementation with this element has been proven to be beneficial for multiple pathologies. Furthermore, the usefulness of organic-selenium compounds has been studied in many disorders, showing promising results. The aim of this review is to analyse the available literature regarding the role of selenium in Chagas disease in order to determine whether its use could be beneficial for the management of this pathology.
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•Patients with selenium deficiency showed more severe forms of the disease.•Se supplementation reduced parasitemia and increased survival in infected mice.•Se showed beneficial effects for the cardiac and gastrointestinal manifestations.•Novel organoselenium compounds have shown promising activity in vitro.
There is a growing appreciation that it is not just the total intake of dietary Se that is important to health but that the species of Se ingested may also be important. The present review attempts ...to catalogue what is known about Se species in foods and supplements and the health effects in which they are implicated. The biosynthetic pathways involved in Se assimilation by plants and the way in which Se species are metabolised in animals are presented in order to give an insight into the species likely to be present in plant and animal foods. Known data on the species of Se in the food chain and in food supplements are tabulated along with their concentrations and the analytical methodology used. The latter is important, since identification that is only based on retention-time matching with authentic standards must be considered as tentative: for evidence of structural confirmation, fragmentation of the molecular ion in addition to MS data is required. Bioavailability, as normally defined, is higher for organic Se species. Health effects, both beneficial and toxic, thought to be associated with specific Se species are described. Potent anti-tumour effects have been attributed to the low-molecular-weight species, Se-methyl-selenocysteine and its γ-glutamyl-derivative, found in a number of edible plants of the Allium and Brassica families. There remain considerable gaps in our knowledge of the forms of Se that naturally occur in foods. Without adequate knowledge of Se speciation, false conclusions may be drawn when assessing Se requirements for optimal health.
•Se is essential for several microalgae, but it exerts toxicity at high concentration.•Se oxyanions influence the uptake of other nutrients and heavy metals by algae.•Se contamination due to ...Se-containing drainage waters and fly ash is of concern.•Se-enriched microalgae might be used as valuable dietary Se supplement.
Selenium (Se) is an intriguing element because it is metabolically required by a variety of organisms, but it may induce toxicity at high doses. Algae primarily absorb selenium in the form of selenate or selenite using mechanisms similar to those reported in plants. However, while Se is needed by several species of microalgae, the essentiality of this element for plants has not been established yet. The study of Se uptake and accumulation strategies in micro- and macro-algae is of pivotal importance, as they represent potential vectors for Se movement in aquatic environments and Se at high levels may affect their growth causing a reduction in primary production. Some microalgae exhibit the capacity of efficiently converting Se to less harmful volatile compounds as a strategy to cope with Se toxicity. Therefore, they play a crucial role in Se-cycling through the ecosystem. On the other side, micro- or macro-algae enriched in Se may be used in Se biofortification programs aimed to improve Se content in human diet via supplementation of valuable food. Indeed, some organic forms of selenium (selenomethionine and methylselenocysteine) are known to act as anticarcinogenic compounds and exert a broad spectrum of beneficial effects in humans and other mammals. Here, we want to give an overview of the developments in the current understanding of Se uptake, accumulation and metabolism in algae, discussing potential ecotoxicological implications and nutritional aspects.
Selenium is regulated in the body to maintain vital selenoproteins and to avoid toxicity. When selenium is limiting, cells utilize it to synthesize the selenoproteins most important to them, creating ...a selenoprotein hierarchy in the cell. The liver is the central organ for selenium regulation and produces excretory selenium forms to regulate whole-body selenium. It responds to selenium deficiency by curtailing excretion and secreting selenoprotein P (Sepp1) into the plasma at the expense of its intracellular selenoproteins. Plasma Sepp1 is distributed to tissues in relation to their expression of the Sepp1 receptor apolipoprotein E receptor-2, creating a tissue selenium hierarchy.
N
-terminal Sepp1 forms are taken up in the renal proximal tubule by another receptor, megalin. Thus, the regulated whole-body pool of selenium is shifted to needy cells and then to vital selenoproteins in them to supply selenium where it is needed, creating a whole-body selenoprotein hierarchy.
To exploit the plant byproducts from selenium (Se) biofortification and reduce environmental risk of inorganic Se fertilizer, pot experiment was conducted in this study. The effects of Se-enriched ...wheat (Triticum aestivum L.) straw (WS + Se) and pak choi (Brassica chinensis L.) (P + Se) amendment on organo-selenium speciation transformation in soil and its bioavailability was evaluated by pak choi uptake. The Se contents of the cultivated pak choi in treatments amended with the same amount of Se-enriched wheat straw and pak choi were 1.7 and 9.7 times in the shoots and 2.3 and 6.3 times in the roots compared with control treatment. Soil respiration rate was significantly increased after all organic material amendment in soil (p < 0.05), which accelerated the mineralization of organic materials and thus resulted in soluble Se (SOL-Se), exchangeable Se (EX-Se), and fulvic acid-bound Se (FA-Se) fraction increasing by 25.2–29.2%, 9–13.8%, and 4.92–8.28%, respectively. In addition, both Pearson correlation and cluster analysis showed that EX-Se and FA-Se were better indicators for soil Se availability in organic material amendment soils. The Marquardt–Levenberg Model well described the dynamic kinetics of FA-Se content after Se-enriched organic material amendment in soil mainly because of the mineralization of organic carbon and organo-selenium. The utilization of Se in P + Se treatment was significantly higher than those in WS + Se treatment because of the different mineralization rates and the amount of FA-Se in soil. Se-enriched organic materials amendment can not only increase the availability of selenium in soil but also avoid the waste of valuable Se source.
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•Se-enriched pak choi amendment resulted in better Se utilization efficiency than wheat straw.•Se-enriched organic material amendments elevated soil Se availability through increasing FA-Se fraction.•EX-Se and FA-Se fraction could better reflect Se availability in organic materials amended soils.•The dynamic kinetics of FA-Se could be well described by Marquardt–Levenberg Model.
Abstract For investigating the effect of selenium on the growth of rice seedlings, this study used different concentrations of selenium ions (0, 0.5, 5, 10 and 20 µmol/L) to treat rice seedlings ...hydroponically. The experimental findings demonstrated that rice seedlings could grow and develop properly in the presence of a selenium deficiency (0 mol/L). Selenium ions had a positive impact on the development of rice seedlings at low and middle selenium concentrations of 0.5 mol/L and 5 mol/L, boosting plant height, above-ground fresh and dry weights. Selenium ions had a substantial inhibitory impact on the development of rice seedlings at high selenium concentrations of 10 mol/L and 20 mol/L.
Selenium is an essential trace element for regulating immune functions through redox-regulating activity of selenoproteins (e.g. glutathione peroxidase), protecting immune cells from oxidative ...stress. However, in cancer, selenium has biological bimodal action depending on the concentration. At nutritional low doses, selenium, depending on its form, may act as an antioxidant, protecting against oxidative stress, supporting cell survival and growth, thus, plays a chemo-preventive role; while, at supra-nutritional higher pharmacological doses, selenium acts as pro-oxidant inducing redox signalling and cell death. To date, many studies have been conducted on the benefits of selenium intake in reducing the risk of cancer incidence at the nutritional level, indicating that likely selenium functions as an immunostimulator, i.e. reversing the immunosuppression in tumour microenvironment towards antitumour immunity by activating immune cells (e.g. M1 macrophages and CD8+ T-lymphocytes) and releasing pro-inflammatory cytokines such as interferon-gamma; whereas, fewer studies have explored the effects of supra-nutritional or pharmacological doses of selenium in cancer immunity. This review, thus, systematically analyses the current knowledge about how selenium stimulates the immune system against cancer and lay the groundwork for future research. Such knowledge can be promising to design combinatorial therapies with Selenium-based compounds and other modalities like immunotherapy to lower the adverse effects and increase the efficacy of treatments.
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•Se is an essential element for regulating immune functions.•Se reverses immunosuppression in the tumour microenvironment.•Effects of Se on cancer immunity are neglected and require more detailed studies.
Selenium nanoparticles (SeNPs) have attracted considerable attention globally due to their significant potential for alleviating abiotic stresses in plants. Accordingly, further research has been ...conducted to develop nanoparticles using chemical ways. However, our knowledge about the potential benefit or phytotoxicity of bioSeNPs in rapeseed is still unclear. Herein, we investigated the effect of bioSeNPs on growth and physiochemical attributes, and selenium detoxification pathways compared to sodium selenite (Se (IV)) during the early seedling stage under normal and salt stress conditions. Our findings showed that the range between optimal and toxic levels of bioSeNPs was wider than Se (IV), which increased the plant's ability to reduce salinity-induced oxidative stress. BioSeNPs improved the phenotypic characteristics of rapeseed seedlings without the sign of toxicity, markedly elevated germination, growth, photosynthetic efficiency and osmolyte accumulation versus Se (IV) under normal and salt stress conditions. In addition to modulation of Na
and K
uptake, bioSeNPs minimized the ROS level and MDA content by activating the antioxidant enzymes engaged in ROS detoxification by regulating these enzyme-related genes expression patterns. Importantly, the main effect of bioSeNPs and Se (IV) on plant growth appeared to be correlated with the change in the expression levels of Se-related genes. Our qRT-PCR results revealed that the genes involved in Se detoxification in root tissue were upregulated upon Se (IV) treated seedlings compared to NPs, indicating that bioSeNPs have a slightly toxic effect under higher concentrations. Furthermore, bioSeNPs might improve lateral root production by increasing the expression level of LBD16. Taken together, transamination and selenation were more functional methods of Se detoxification and proposed different degradation pathways that synthesized malformed or deformed selenoproteins, which provided essential mechanisms to increase Se tolerance at higher concentrations in rapeseed seedlings. Current findings could add more knowledge regarding the mechanisms underlying bioSeNPs induced plant growth.
Dietary selenium (Se), mainly through its incorporation into selenoproteins, plays an important role in inflammation and immunity. Adequate levels of Se are important for initiating immunity, but ...they are also involved in regulating excessive immune responses and chronic inflammation. Evidence has emerged regarding roles for individual selenoproteins in regulating inflammation and immunity, and this has provided important insight into mechanisms by which Se influences these processes. Se deficiency has long been recognized to negatively impact immune cells during activation, differentiation, and proliferation. This is related to increased oxidative stress, but additional functions such as protein folding and calcium flux may also be impaired in immune cells under Se deficient conditions. Supplementing diets with above-adequate levels of Se can also impinge on immune cell function, with some types of inflammation and immunity particularly affected and sexually dimorphic effects of Se levels in some cases. In this comprehensive article, the roles of Se and individual selenoproteins in regulating immune cell signaling and function are discussed. Particular emphasis is given to how Se and selenoproteins are linked to redox signaling, oxidative burst, calcium flux, and the subsequent effector functions of immune cells. Data obtained from cell culture and animal models are reviewed and compared with those involving human physiology and pathophysiology, including the effects of Se levels on inflammatory or immune-related diseases including anti-viral immunity, autoimmunity, sepsis, allergic asthma, and chronic inflammatory disorders. Finally, the benefits and potential adverse effects of intervention with Se supplementation for various inflammatory or immune disorders are discussed.
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