Essentiality Of Selenium Research Articles

Joint Biofortification of Plants with Selenium and Iodine: New Field of Discoveries.

The essentiality of selenium (Se) and iodine (I) to human beings and the widespread areas of selenium and iodine deficiency determine the high significance of functional food production with high levels of these elements. In this respect, joint biofortification of agricultural crops with Se and I is especially attractive. Nevertheless, in practice this topic has raised many problems connected with the possible utilization of many Se and I chemical forms, different doses and biofortification methods, and the existence of wide species and varietal differences. The limited reports relevant to this subject and the multiplicity of unsolved questions urge the need for an adequate evaluation of the results obtained up-to-date, useful for developing further future investigations. The present review discusses the outcome of joint plant Se–I biofortification, as well as factors affecting Se and I accumulation in plants, paying special attention to unsolved issues. A particular focus has been given to the prospects of herb sprouts production enriched with Se and I, as well as the interactions between the latter microelements and arbuscular-mycorrhizal fungi (AMF).

Joint Selenium-Iodine Supply and Arbuscular Mycorrhizal Fungi Inoculation Affect Yield and Quality of Chickpea Seeds and Residual Biomass.

The essentiality of selenium (Se) and iodine (I) for the human organism and the relationship between these two trace elements in mammal metabolism highlight the importance of the joint Se–I biofortification to vegetable crops in the frame of sustainable farming management. A research study was carried out in southern Italy to determine the effects of the combined inoculation with arbuscular mycorrhizal fungi (AMF) and biofortification with Se and I on plant growth, seed yield, quality, and antioxidant and elemental status, as well as residual biomass chemical composition of chickpea grown in two different planting times (14 January and 28 February). The AMF application improved the intensity of I and Se accumulation both in single and joint supply of these elements, resulting in higher seed yield and number as well as dry weight, and was also beneficial for increasing the content of antioxidants, protein, and macro- and microelements. Earlier planting time resulted in higher values of seed yield, as well as Se, I, N, P, Ca, protein, and antioxidant levels. Se and I showed a synergistic effect, stimulating the accumulation of each other in chickpea seeds. The AMF inoculation elicited a higher protein and cellulose synthesis, as well as glucose production in the residual biomass, compared to the single iodine application and the untreated control. From the present research, it can be inferred that the plant biostimulation through the soil inoculation with AMF and the biofortification with Se and I, applied singly or jointly, proved to be effective sustainable farming tools for improving the chickpea seed yield and/or quality, as well as the residual biomass chemical composition for energy production or beneficial metabolite extraction.

The Protective Role of Selenium Against AFB1-Induced Liver Apoptosis by Death Receptor Pathway in Broilers.

Aflatoxin B1 (AFB1) is the most toxic among the mycotoxins and causes detrimental health effects on the liver of human and animals. Selenium (Se) plays an important role in protection of various animal species against numerous notorious toxic agents. The present study is designed to explore the protective effects of Se against AFB1-induced liver pathogenesis by the methods of histopathology, flow cytometry, quantitative real-time polymerase chain reaction (qRT-PCR), and biochemical analysis. A total of 312, 1-day-old healthy Cobb-500 broilers were randomly divided into four groups and fed with basal diet (control group), 0.6mg/kg AFB1 (AFB1 group), 0.4mg/kg Se (+ Se group), and 0.6mg/kg AFB1 + 0.4mg/kg Se (AFB1 + Se group) for 21days, respectively. Our results showed that 0.4mg/kg Se supplement in broiler's diets could alleviate the AFB1-induced histological lesions in the liver. The apoptosis analysis by flow cytometry showed that 0.4mg/kg Se ameliorated the AFB1-induced apoptosis in the liver. Moreover, the mRNA expression levels of Fas, TNF-α, FAS-associated death domain, TNF receptor-associated death domain, TNF receptor-associated factor 2, caspase 10, caspase 8, B cell lymphoma 2, IκB kinase, X-linked inhibitor of apoptosis protein, caspase 9, and caspase 3 analyzed by qRT-PCR demonstrated that 0.4mg/kg Se could relieve the impact caused by AFB1 to these parameters. The biochemical analyses of activities of CAT, GSH-Px and SOD, hydroxyl ion scavenging and contents of MDA and GSH in liver cells also indicated that 0.4mg/kg Se has positive effect on AFB1-induced oxidative stress in the liver. In conclusion, Se could relieve AFB1-induced apoptosis by the molecular regulation of death receptors pathway in the liver of broilers. The outcomes from the present study may lead to a better understanding of the nature of selenium's essentiality and its protective roles against AFB1.

The Molecular Mechanisms of Protective Role of Se on the G2/M Phase Arrest of Jejunum Caused by AFB1.

Aflatoxin B1 (AFB1) is the most toxic among the mycotoxins and causes detrimental health effects on human and animals. Selenium (Se) plays an important role in chemopreventive, antioxidant, anticarcinogen, and detoxification and involved in cell cycle regulation. The aim of this study was to explore the molecular mechanisms of selenium involved in inhibition of G2/M cell cycle arrest of broiler's jejunum. A total of 240 one-day-old healthy Cobb broilers were randomly divided into four groups and fed with basal diet (control group), 0.6mg/kg AFB1 (AFB1 group), 0.4mg/kg Se (+Se group), and 0.6mg/kg AFB1 + 0.4mg/kg Se (AFB1 + Se group) for 21days, respectively. The histological observation and morphological analysis revealed that 0.4mg/kg Se prevented the AFB1-associated lesions of jejunum including the shedding of the apical region of villi, the decreased villus height, and villus height/crypt ratio. The cell cycle analysis by flow cytometry showed that 0.4mg/kg Se ameliorated the AFB1-induced G2/M phase arrest in jejunal cells. Moreover, the expressions of ATM, Chk2, p53, Mdm2, p21, PCNA, Cdc25, cyclin B, and Cdc2 analyzed by immunohistochemistry and qRT-PCR demonstrated that 0.4mg/kg Se restored these parameters to be close to those in the control group. In conclusion, Se promoted cell cycle recovery from the AFB1-induced G2/M phase arrest by the molecular regulation of ATM pathway in the jejunum of broilers. The outcomes from the present study may lead to a better understanding of the nature of selenium's essentiality and its protective roles against AFB1.

Toenail selenium as an indicator of environmental exposure: A cross-sectional study.

The relation between toxicity and essentiality of selenium(Se) is of growing interest in human health, as the effects may widely differ depending of its different chemical species and the exposure levels. Toenail Se has been proposed as a reliable biomarker of long-term Se exposure, but few studies investigated the correlation between its toenail content and environmental determinants(i.e.,dietary food intake). We aimed to determine the relation of toenail Se levels with serum Se species as well as food items. We recruited a random sample of Modena(Northern Italy) municipal residents, from whom we collected detailed personal information, dietary habits, toenail specimen for Se determination and a blood sample for serum Se speciation analysis. Toenail Se mean value was 0.96µg/g(range,0.47‑1.60), with slightly higher levels in females, in non-obese subjects and in Se supplements users, while it was lower in current smokers. Toenail Se positively correlated with organic Se forms, mainly selenoproteinP and selenocysteine, and inversely with the inorganic forms (selenite and selenate). Toenail Se was not associated with meat, cereals and dairy products consumption, positively correlated with fruit and slightly with vegetable intake, and negatively with fish and seafood consumption. Finally, no clear association emerged with estimated air Se exposure.

Ecological Importance of Insects in Selenium Biogenic Cycling

Selenium is an essential trace element for animal and human beings. Despite the importance of insects in most ecosystems and their significant contribution to the biological cycling of trace elements due to high abundance, population productivity, and diverse ecosystem functions, surprisingly little information is available on selenium bioaccumulation by these arthropods. This review considers selenium essentiality and toxicity to insects as well as insects’ contribution to selenium trophic transfer through the food chains. Data on Se accumulation by insects of the Dniester River Valley with no anthropogenic Se loading reveal typically low Se content in necrophagous insects compared to predators and herbivores and seasonal variations in Se accumulation.

Reproductive toxicity of di(2-ethylhexyl) phthalate in selenium-supplemented and selenium-deficient rats

Phthalates are abundantly produced plasticizers, and di(ethylhexyl) phthalate (DEHP) is the most widely used derivative in various consumer products and medical devices. Animal studies show that DEHP and various other phthalates cause reproductive and developmental toxicity. Although the evidences are limited, it seems reasonable that DEHP may have a potential for similar adverse effects in humans. Such concerns are increasing, particularly for the developing reproductive system of male infants and children. By taking into account the essentiality of selenium (Se) in testicular structure and functions and the high prevalence of inadequate Se intake in various part of the world, this study was designed to investigate the testicular toxicity of DEHP in Se-deficient male rats and to examine the possible preventive effects of Se supplementation on phthalate toxicity. Se deficiency was generated by feeding 3-week-old Sprague-Dawley rats with a ≤0.05 Se mg/kg diet for 5 weeks. Supplementation groups were on a 1 mg Se/kg diet, and DEHP-treated groups received a 1,000 mg/kg dose by gavage during the last 10 days of the feeding period. Testicular histopathology, sperm count and motility, and sperm morphology were examined, and plasma levels of sex hormones were measured. Toxicity and antiandrogenic effects of DEHP were evidenced by disturbed testicular histology and spermatogenesis, diminished testosterone, leutinizing hormone (LH) and follicle stimulating hormone (FSH) levels, and sperm motility. The effects of DEHP were much more pronounced in Se-deficient rats, whereas Se supplementation was found to be protective, reflecting its regulating role in cellular redox equilibrium.

Selenoproteins: the key factor in selenium essentiality. State of the art analytical techniques for selenoprotein studies

Selenium is an essential element for human health. The benefits of selenium are many including protection against cancer, heart diseases and other cardiovascular and muscle disorders. Selenium is also helpful in controlling gastrointestinal disorders, enhancing immunity of the human body and reducing age-related diseases. The health-promoting properties of Se are due to vital functions of selenoproteins in which selenium is present as selenocysteine, the 21st amino acid. To date, dozens of selenoprotein families have been described though many have roles that have not been fully elucidated. Selenoproteins research has attracted tremendous interest from different scientific areas. Analytical chemists have not remained indifferent to the attractive features of these unique proteins. Different analytical techniques, such as multidimensional chromatography-inductively coupled plasma mass spectrometry (ICPMS), electrospray (tandem) mass spectrometry (ESI-MS/MS), matrix-assisted laser desorption ionization time-of flight (MALDI-TOF) and sodium dodecyl sulphate polyacrylamide gel electrophoresis-laser ablation inductively coupled plasma mass spectrometry (SDS-PAGE-LA-ICPMS), have been applied to the determination of selenoproteins and selenium-containing proteins. This review describes the best-characterized selenoproteins to date in addition to the major contributions of analytical chemistry to the field of selenoproteins. The article also highlights the challenges of combining elemental and molecular mass spectrometry for the determination of selenoproteins and selenium-containing proteins.

Agronomic Biofortification with Selenium

Although the essentiality of selenium (Se) has been known for five decades, the most effective method of Se delivery to cattle is unclear. Se may be administered as an injection or in feed and mineral supplements, with Se usually provided as inorganic sodium selenite. One limitation of inorganic Se is the apparent short duration of Se storage in the body. Natural Se sources in plants are organic forms, namely selenomethionine, selenocysteine, or Se-methylselenocysteine. Organic Se accumulates in muscle as selenoproteins, and subsequently becomes available during dietary inadequacy or during stress conditions when the Se requirement is increased but feed consumption is decreased. Agronomic biofortification is defined as increasing the bioavailable concentration of an essential element in edible portions of crop plants through the use of fertilizers. The purpose of this study was to evaluate Se status in beef cattle after short-term exposure to high-Se-fertilized forage vs a commonly used mineral supplement containing inorganic sodium selenite.

Selenium as an essential micronutrient: roles in cell cycle and apoptosis.

Selenium is an essential trace element for humans and animals, and selenium deficiency is associated with several disease conditions such as immune impairment. In addition, selenium intakes that are greater than the recommended daily allowance (RDA) appear to protect against certain types of cancers. In humans and animals, cell proliferation and death must be regulated to maintain tissue homeostasis, and it has been well documented that numerous human diseases are directly related to the control of cell cycle progression and apoptosis. Thus, the elucidation of the mechanisms by which selenium regulates the cell cycle and apoptosis can lead to a better understanding of the nature of selenium’s essentiality and its role in disease prevention. This article reviews the status of knowledge concerning the effect of selenium on cell cycle and apoptosis.

Human Health Risks of Selenium-Contaminated Fish: A Case Study for Risk Assessment of Essential Elements

ABSTRACT A screening level human health risk assessment (HHRA) was applied to evaluate the human health implications of consuming selenium found in fish tissues collected downstream of coal mines in southeastern British Columbia, Canada. The study evaluated the potential for adverse human health effects associated with selenium, and considered known and potential benefits of selenium and fish ingestion. The results indicated that risks of selenosis due to consumption of selenium-contaminated fish in the region are negligible. Conclusions were strengthened by consideration of the potential benefits of selenium to human health, including: selenium essentiality for maintenance of good health; potential cancer prevention properties due to its role as an antioxidant; potential benefits for cardiovascular health; and other positive health benefits. The findings indicated that some aspects of the traditional framework for HHRA (e.g., application of safety factors to “err on the side of safety”) are inappropriate for the assessment of selenium-contaminated fish. Due to both deficiency and toxicity in the selenium dose-response relationship, application of compounding conservatism in risk assessment may lead to recommended intakes of fish that are contrary to the public health interest. The need for balancing risk types, for incorporating positive responses in risk assessments, and the linkage to the precautionary principle, are discussed.

Selenite and Selenomethionine Promote HL-60 Cell Cycle Progression

The essential role of selenium (Se) in nutrition is well established. The elucidation of the mechanisms by which selenium regulates the cell cycle can lead to a better understanding of the nature of selenium's essentiality and its role in disease prevention. In this study, the effects of selenium deficiency or adequacy (0.25 micromol/L selenite or selenomethionine) on HL-60 cell cycle progression were examined in serum-free media. Selenium was critical for promotion of HL-60 cell growth. Cell-cycle analysis revealed that selenium deficiency caused a decrease in G1 phase cells that corresponded to an increase in G2 and sub-G1 phase cells. Gene array analysis suggested that c-Myc, cyclin C, proliferating cell nuclear antigen, cyclin-dependent kinase (cdk)1, cdk2, cdk4, cyclin B and cyclin D2 mRNA levels were lower in selenium-deficient cells than in the cells supplemented with 0.25 micromol/L selenomethionine. The decrease in the c-Myc mRNA level in selenium-deficient cells was confirmed by reverse transcription-polymerase chain reaction analysis. Furthermore, the phosphorylation state of total cellular protein was higher (57%) in selenium-supplemented cells than in selenium-deficient cells. Collectively, these results suggest a novel role for selenium at 0.25 micromol/L in up-regulation of the expression of numerous cell cycle-related genes and total cellular phosphorylated proteins in HL-60 cells in serum-free culture media. This leads to the promotion of cell cycle progression, particularly G2/M transition and/or the reduction of apoptosis, primarily in G1 cells. These observations may have additional implications for understanding the nature of selenium's essentiality.

Essentiality of selenium in the human body: relationship with different diseases

In the present review different aspects related to the essential element selenium in the human organism are considered. A large number of human studies have been performed in order to improve knowledge on the influence of this element in the origin and development of several degenerative diseases. Selenium deficiencies among human beings as well as animals are being recognized worldwide to be related to a number of pathologies. This element has also the special characteristic that the range between its essential and toxic character is very close, and consequently daily dietary intake should be appropriately monitored in individuals. Nevertheless, nowadays there is still a lot of controversy about the optimum dietary level of this element in order to cure or to prevent the appearance of diseases such as cirrhosis, cancer, diabetes, or cardiovascular pathologies. Results obtained in several animal and epidemiological studies have indicated that Se could constitute a dietary factor with protective action against several degenerative diseases.

Importance and physiologic nutritional requirement of the selenium trace element within the scope of parenteral nutrition (TPN)

Selenium-responsive clinical manifestations of selenium deficiency and elucidation of the biochemical and molecular biological basis of the essentiality of selenium give evidence for the biological importance of the trace element in human nutrition. The dietary parenteral selenium requirement can be calculated on the basis of the maximal gene expression of the selenoprotein plasma glutathione peroxidase (plGPx). In total parenteral nutrition a daily requirement of 0.01 mumol/kg body weight for adults and 0.025 mumol/kg body weight for children can be seen as adequate and safe.

Selenium-mediated biochemical changes in Japanese quail

Essentiality of selenium (Se) for Japanese quail,Coturnix coturnix japonica, was confirmed using a formulated semipurified low-Se diet (basal) (0.05 ppm). Selenium-deficiency symptoms appeared in quails on this diet within 15 d, which corresponded to low levels of hemolysate glutathione peroxidase (GSH-Px) activity. Selenium administration at 0.05 and 2.0 ppm levels resulted in an increase of hemolysate GSH-Px activity by 64 and 116%, respectively, in both short- and long-term experiments. Growth over a 2-mo period increased the hemolysate GSH-Px activity by 120% at each level of dietary Se. A differential response was exhibited by hepatic mitochondrial and soluble GSH-Px activity to Se supplementation, the former increasing progressively with increments of Se at 0.05, 2.0, and 4.0 ppm by 45, 70 and 150%, respectively. The soluble GSH-Px activities of tissues, such as liver, kidney, and testis, and RBC membrane-bound activity remained unchanged in long-term studies at different levels of Se. Replenishment of Se to quails maintained on low-Se diets reflected no change in RBC membrane-bound and liver-soluble GSH-Px activities, although the activity in hemolysate increased consistently with Se. The GSH-Px activity in hemolysate was restored to the levels comparable to those of long-term studies only at Se administration at the 2.0-ppm level. The differential response of mitochondrial and soluble GSH-Px activities to Se and other related observations on mitochondrial functions suggest an additional role for Se in mitochondrial membrane processes and glutathione-related metabolic regulations.