Selenium metabolism and bioavailability

The effect of hydroxy-selenomethionine on the productive and reproductive performance of old broiler breeders

BACKGROUND

Selenium (Se) is a rare essential element that plays a vital role in the health and performance of animals. By interfering in the production of antioxidant enzymes such as glutathione peroxidase, thioredoxin reductase and methionine sulfoxide, Se plays a role in reducing the effects of oxidative stress and animal performance.

OBJECTIVES

This study aimed to investigate the effect of hydroxy-selenomethionine (OH-SeMet) in the diet of broiler breeder and old broiler breeder roosters on productive performance, reproduction and sperm quality parameters.

METHODS

For this purpose, 260 broiler breeders of the Ross 308 strain were used in a completely randomized design with four treatments and five replications (13 hens and one rooster in each replication). Experimental treatments included: (1) a basal diet without OH-SeMet (T1:control), (2) a broiler breeder diet without OH-SeMet and a rooster diet containing 0.1 mg/kg OH-SeMet (T2), (3) broiler breeder diet containing 0.1 mg/kg OH-SeMet and rooster diet without OH-SeMet (T3) and (4) broiler breeder and rooster diet contained 0.1 mg/kg OH-SeMet (T4).

RESULTS

The results showed that T3 and T4 treatments improved egg production, egg weight, egg mass and feed conversion ratio (FCR) compared to the control treatment (p < 0.05). The fertility and hatchability percentages of T4 and T2 treatments increased compared to T1 and T3 treatments (p < 0.05). The rate of embryonic losses in T1 was higher than in other treatments. However, grade one chickens were higher in T4 than in other treatments (p < 0.05). Total motility and viability of sperms were significantly higher in T2 and T4 treatments than in T1 and T3 treatments. The sperm abnormality percentage and sperm MDA concentration decreased in T2 and T4 treatments.

CONCLUSIONS

Therefore, using OH-SeMet may be a practical approach to help old broiler breeders' production and reproduction performance.

A screening for optimal selenium enrichment additives for selenium-enriched fish production: Application of a HPLC-ICP-MS method

The production of selenium-enriched fish contributes to alleviating selenium deficiency for humans. In this study, selenium nanoparticles (SeNPs) comparable in bioavailability to selenomethionine (SeMet), increased SeMet content in O. macrolepis (Onychostoma macrolepis) muscle. Additionally, dietary SeNPs significantly enhanced selenocysteine (SeCys2) and methylselenocysteine (MeSeCys) levels in O. macrolepis muscle. The effect of SeNPs on selenium speciation in grass carp muscle was consistent with O. macrolepis results. SeCys2 and MeSeCys showed antioxidant capacity in HEK293T cells, indicating enhanced health benefits of Se-enriched fish produced using SeNPs. Furthermore, the addition of 0.3 mg/kg SeNPs significantly improved the flesh quality of O. macrolepis by reducing the content of crude fat and heavy metals, as well as increasing the levels of crude protein, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and the ratio of n-3/n-6 polyunsaturated fatty acids (PUFAs). Therefore, selenium-enriched fish produced from SeNPs is a good source for improving human dietary selenium intake.

Lacticaseibacillus rhamnosus GG Improves Periodontal Bone Repair via Gut-Blood Axis in Hyperlipidemia

Periodontal bone regeneration remains a clinical challenge, and hyperlipidemia can aggravate alveolar bone resorption. Probiotics have recently been reported to improve bone mass. We aimed to determine the role of Lacticaseibacillus rhamnosus GG (LGG) in periodontal bone regeneration improvement within the context of periodontitis with hyperlipidemia. A Sprague Dawley rat model for periodontitis, hyperlipidemia, and periodontal fenestration defect was constructed (n = 36) and administered LGG gavage for 6 wk (the rats were subsequently sacrificed). Fecal microbiota from donor rats 3 wk after LGG gavage was transplanted into recipient rats to evaluate the role of LGG-modulated gut microbiota in periodontal bone regeneration. Regenerated bone mass was detected using micro-computerized tomography and hematoxylin and eosin stain. Gut microbiota was analyzed using 16S ribosomal RNA sequencing. Serum metabolites were detected by liquid chromatography-mass spectrometry (6 wk after LGG gavage). The pro-osteogenic effects of screened serum metabolite were verified in vitro on bone marrow mesenchymal stem cells (BMMSCs). We found that the bone mineral density, bone volume (BV), trabecular bone volume fraction (BV/TV), and trabecular thickness of the regenerated periodontal bone increased after LGG gavage (P < 0.05) but had little effect on oral flora. After LGG gavage, Staphylococcus, Corynebacterium, and Collinsella in the gut of donors were significantly changed, and these differences were maintained in recipients, who also showed increased trabecular thickness of the regenerated periodontal bone (P < 0.05). These key genera were correlated with BV/TV and BV (P < 0.05). In addition, LGG gavage significantly regulated bone-related blood metabolites, of which selenomethionine promoted BMMSC osteogenesis. Notably, selenomethionine was associated with key gut genera (P < 0.05). Collectively, LGG improved periodontal bone regeneration in the context of periodontitis with hyperlipidemia by modulating gut microbiota and increasing pro-osteogenic metabolites in the blood. These results reveal new insights into the use of probiotics to promote periodontal bone regeneration via the gut-blood-bone axis.

Influence of Dietary Fibre and Protein Fractions on the Trace Element Bioaccessibility of Turnip Tops (Brassica rapa) Growing under Mediterranean Conditions

The objective of this work was to study the influence of three dietary fibre fractions (pectin, gum arabic and cellulose) and three protein fractions (casein, lactalbumin and soy) on the trace element bioaccessibility (Fe, Mn, Ni, Se and Zn) of turnip tops (B. rapa subsp. Rapa) growing under Mediterranean conditions. Then, it aimed to promote the use of this vegetable not only for direct fresh consumption but also as a main ingredient in the development of food mixtures. The results showed that soluble fibre fractions, such as pectin and gum arabic, can enhance the bioaccessibility of trace elements, such as Fe, Mn, Se and Zn. This effect was not proved for cellulose (an insoluble fibre fraction), in which, at best, no bioaccessibility effect was observed. Regarding the protein fractions, with the exception of Se, caseins and lactalbumin had a neutral effect on improving the trace element bioaccessibility. This did not hold true for soy protein, in which a considerable improvement in the bioaccessibility of Fe, Mn, Se and Zn was determined.

Agronomic and Genetic Strategies to Enhance Selenium Accumulation in Crops and Their Influence on Quality

Selenium (Se) is an essential trace element that plays a crucial role in maintaining the health of humans, animals, and certain plants. It is extensively present throughout the Earth's crust and is absorbed by crops in the form of selenates and selenite, eventually entering the food chain. Se biofortification is an agricultural process that employs agronomic and genetic strategies. Its goal is to enhance the mechanisms of crop uptake and the accumulation of exogenous Se, resulting in the production of crops enriched with Se. This process ultimately contributes to promoting human health. Agronomic strategies in Se biofortification aim to enhance the availability of exogenous Se in crops. Concurrently, genetic strategies focus on improving a crop's capacity to uptake, transport, and accumulate Se. Early research primarily concentrated on optimizing Se biofortification methods, improving Se fertilizer efficiency, and enhancing Se content in crops. In recent years, there has been a growing realization that Se can effectively enhance crop growth and increase crop yield, thereby contributing to alleviating food shortages. Additionally, Se has been found to promote the accumulation of macro-nutrients, antioxidants, and beneficial mineral elements in crops. The supplementation of Se biofortified foods is gradually emerging as an effective approach for promoting human dietary health and alleviating hidden hunger. Therefore, in this paper, we provide a comprehensive summary of the Se biofortification conducted over the past decade, mainly focusing on Se accumulation in crops and its impact on crop quality. We discuss various Se biofortification strategies, with an emphasis on the impact of Se fertilizer strategies on crop Se accumulation and their underlying mechanisms. Furthermore, we highlight Se's role in enhancing crop quality and offer perspective on Se biofortification in crop improvement, guiding future mechanistic explorations and applications of Se biofortification.

Transcriptomic Changes in Response to Form of Selenium on the Interferon-Tau Signaling Mechanism in the Caruncular Tissue of Beef Heifers at Maternal Recognition of Pregnancy

We have reported that selenium (Se) provided to grazing beef cattle in an inorganic (ISe) form versus a 1:1 mixture (MIX) of inorganic and organic (OSe) forms affects cholesterol biosynthesis in the corpus luteum (CL), the abundance of interferon tau (IFNτ) and progesterone (P4)-induced mRNAs in the caruncular (CAR) tissue of the endometrium, and conceptus length at maternal recognition of pregnancy (MRP). In this study, beef heifers were supplemented with a vitamin-mineral mix containing 35 ppm Se as ISe or MIX to achieve a Se-adequate status. Inseminated heifers were killed at MRP (d 17, n = 6 per treatment) for tissue collection. In CAR samples from MIX versus ISe heifers, qPCR revealed that mRNA encoding the thyroid regulating DIO2 and DIO3 was decreased (p < 0.05) and a complete transcriptomic analysis revealed effects on the interferon JAK-STAT1/2 pathway, including decreased expression of mRNAs encoding the classical interferon stimulated genes IFIT1, IFIT2, IFIT3, IRF1, IRF9, ISG15, OAS2, and RSAD2 (p < 0.05). Treatment also affected the abundance of mRNAs contributing to the immunotolerant environment (p < 0.05). In combination, these findings suggest more advanced preparation of the CAR and developing conceptus for implantation and to evade immune rejection by the maternal system in MIX- vs. ISe-treated heifers.

Potential role of selenium in modifying the effect of maternal methylmercury exposure on child neurodevelopment - A review

Selenium (Se) is an essential trace element for normal neurodevelopment. It is incorporated into multiple selenoenzymes which have roles in the brain and neurological function, the synthesis of thyroid hormones, the antioxidant defense system, DNA synthesis, and reproduction. Fish is a source of both Se and neurotoxic methylmercury (MeHg). Selenium is known to ameliorate the effects of MeHg in experimental animals, but studies in children exposed to both Se and MeHg through prenatal fish consumption have been inconclusive. Research on Se's implications for pregnancy and child neurodevelopment is limited. The aims of this review are to summarize the literature on the biological roles of Se during pregnancy and the potential role in mitigating the effects of MeHg exposure from fish consumption on human health. This review has shown that Se concentrations among pregnant women globally appear insufficient, with the majority of pregnant women reporting Se concentrations below 70 µg/L during pregnancy. The role of Se in child development and its interactions with MeHg in children are inconclusive. Further investigation of the interaction between Se and MeHg in relation to child neurodevelopment in high fish-eating populations is required to fully elucidate effects.

GPX4 in cell death, autophagy, and disease

Selenoprotein GPX4 (glutathione peroxidase 4), originally known as PHGPX (phospholipid hydroperoxide glutathione peroxidase), is the main oxidoreductase in the use of glutathione as a reducing agent in scavenging lipid peroxidation products. There are three GPX4 isoforms: cytosolic (cGPX4), mitochondrial (mGPX4), and nuclear (nGPX4), with distinct spatiotemporal expression patterns during embryonic development and adult life. In addition to inducing the main phenotype of ferroptosis, the loss of GPX4 can in some cells trigger apoptosis, necroptosis, pyroptosis, or parthanatos, which mediates or accelerates developmental defects, tissue damage, and sterile inflammation. The interaction of GPX4 with the autophagic degradation pathway further modulates cell fate in response to oxidative stress. Impaired GPX4 function is implicated in tumorigenesis, neurodegeneration, infertility, inflammation, immune disorders, and ischemia-reperfusion injury. Additionally, the R152H mutation in GPX4 can promote the development of Sedaghatian-type spinal metaphyseal dysplasia, a rare and fatal disease in newborns. Here, we discuss the roles of classical GPX4 functions as well as emerging GPX4-regulated processes in cell death, autophagy, and disease.Abbreviations: AA: arachidonic acid; cGPX4: cytosolic GPX4; CMA: chaperone-mediated autophagy; DAMPs: danger/damage-associated molecular patterns; mGPX4: mitochondrial GPX4; nGPX4: nuclear GPX4; GSDMD-N: N-terminal fragment of GSDMD; I/R: ischemia-reperfusion; PLOOH: phospholipid hydroperoxide; PUFAs: polyunsaturated fatty acids; RCD: regulated cell death; ROS: reactive oxygen species; Se: selenium; SSMD: Sedaghatian-type spondylometaphyseal dysplasia; UPS: ubiquitin-proteasome system.

Time-Resolved Examination of Fungal Selenium Redox Transformations

Selenium (Se) is both a micronutrient required for most life and an element of environmental concern due to its toxicity at high concentrations, and both bioavailability and toxicity are largely influenced by the Se oxidation state. Environmentally relevant fungi have been shown to aerobically reduce Se(IV) and Se(VI), the generally more toxic and bioavailable Se forms. The goal of this study was to shed light on fungal Se(IV) reduction pathways and biotransformation products over time and fungal growth stages. Two Ascomycete fungi were grown with moderate (0.1 mM) and high (0.5 mM) Se(IV) concentrations in batch culture over 1 month. Fungal growth was measured throughout the experiments, and aqueous and biomass-associated Se was quantified and speciated using analytical geochemistry, transmission electron microscopy (TEM), and synchrotron-based X-ray absorption spectroscopy (XAS) approaches. The results show that Se transformation products were largely Se(0) nanoparticles, with a smaller proportion of volatile, methylated Se compounds and Se-containing amino acids. Interestingly, the relative proportions of these products were consistent throughout all fungal growth stages, and the products appeared stable over time even as growth and Se(IV) concentration declined. This time-series experiment showing different biotransformation products throughout the different growth phases suggests that multiple mechanisms are responsible for Se detoxification, but some of these mechanisms might be independent of Se presence and serve other cellular functions. Knowing and predicting fungal Se transformation products has important implications for environmental and biological health as well as for biotechnology applications such as bioremediation, nanobiosensors, and chemotherapeutic agents.

Properties of Selenolate-Diselenide Redox Equilibria in View of Their Thiolate-Disulfide Counterparts

Selenium, the multifaceted redox agent, is characterized in terms of oxidation states, with emphasis on selenol and diselenide in proteinogenic compounds. Selenocysteine, selenocystine, selenocysteamine, and selenocystamine are depicted in view of their co-dependent, interfering acid-base, and redox properties. The pH-dependent, apparent (conditional), and pH-independent, highly specific, microscopic forms of the redox equilibrium constants are described. Experimental techniques and evaluation methods for the determination of the equilibrium and redox parameters are discussed, with a focus on nuclear magnetic resonance spectroscopy, which is the prime technique to observe selenium properties in organic compounds. The correlation between redox, acid-base, and NMR parameters is shown in diagrams and tables. The fairly accessible NMR and acid-base parameters are discussed to assess the predictive power of these methods to estimate the site-specific redox properties of selenium-containing moieties in large molecules.

Effects of preharvest sprays of iodine, selenium and calcium on apple biofortification and their quality and storability

The low dietary intake of iodine (I) and selenium (Se) by humans leads to serious health and socioeconomic problems. Therefore, enrichment of plants with I and Se using fertilisers containing these micronutrients is commonly recommended. In this study, we examined the impacts of combined spraying of I as iodide or iodate, Se as selenite or selenate, and calcium (Ca) as Ca-chloride on the enrichment of 'Red Jonaprince' (Malus domestica Borth.) apples, as well as fruit quality and their storability. Sprays were applied 2 weeks before harvest at rates of 0.5 kg I, 0.25 kg Se and 7 kg Ca per ha. Trees not sprayed with these nutrients served as controls. The tested sprays caused leaf burn, but they did not affect the cold injury of buds and shoots. Those sprays had no effect on yield, fruit size and russeting or skin colouring. At harvest, sprayed apples contained about 50 times more I and Se and 30% more Ca than the control fruit. After storage, compared to the control fruit, sprayed apples were firmer, had more organic acids and were less susceptible to disorders, such as bitter pit, internal breakdown and decay caused by Neofabraea spp. The results indicate that preharvest spraying with I, Se and Ca at high rates can be recommended to effectively enrich apples with I and Se and to simultaneously improve their storability.

The Role of Selenoprotein Tissue Homeostasis in MetS Programming: Energy Balance and Cardiometabolic Implications

Selenium (Se) is an essential trace element mainly known for its antioxidant, anti-inflammatory, and anti-apoptotic properties, as it is part of the catalytic center of 25 different selenoproteins. Some of them are related to insulin resistance (IR) and metabolic syndrome (MetS) generation, modulating reactive oxygen species (ROS), and the energetic sensor AMP-activated protein kinase (AMPK); they can also regulate the nuclear transcription factor kappa-B (NF-kB), leading to changes in inflammation production. Selenoproteins are also necessary for the correct synthesis of insulin and thyroid hormones. They are also involved in endocrine central regulation of appetite and energy homeostasis, affecting growth and development. MetS, a complex metabolic disorder, can appear during gestation and lactation in mothers, leading to energetic and metabolic changes in their offspring that, according to the metabolic programming theory, will produce cardiovascular and metabolic diseases later in life. However, there is a gap concerning Se tissue levels and selenoproteins’ implications in MetS generation, which is even greater during MetS programming. This narrative review also provides an overview of the existing evidence, based on experimental research from our laboratory, which strengthens the fact that maternal MetS leads to changes in Se tissue deposits and antioxidant selenoproteins’ expression in their offspring. These changes contribute to alterations in tissues’ oxidative damage, inflammation, energy balance, and tissue function, mainly in the heart. Se imbalance also could modulate appetite and endocrine energy balance, affecting pups’ growth and development. MetS pups present a profile similar to that of diabetes type 1, which also appeared when dams were exposed to low-Se dietary supply. Maternal Se supplementation should be taken into account if, during gestation and/or lactation periods, there are suspicions of endocrine energy imbalance in the offspring, such as MetS. It could be an interesting therapy to induce heart reprogramming. However, more studies are necessary.

Effects of Supplementary Selenium and Vitamin E on the Growth Performance, Antioxidant Enzyme Activity, and Gene Expression of Sea Cucumber Apostichopus japonicus

A 60-day feeding experiment was conducted to evaluate the effects of single selenomethionine (Se) and its mixture with vitamin E (VE) on the growth, antioxidant enzyme activities, and gene expression of juvenile sea cucumber Apostichopus japonicus. The design of the experiment contained two factors and 5 × 2 levels by means of adding various levels of Se and VE in the feed, i.e., combination of 0, 0.3, 0.6, 0.9, or 1.2 mg Se kg^-1 and 0 or 200 mg VE kg^-1. The results revealed that the specific growth rate and weight gain rate were the highest in the group with 0.3 mg Se kg^-1 and 200 mg VE kg^-1, followed by the group with 0.6 mg Se kg^-1 without VE. Se significantly improved the activities of amylase and protease with VE also imposed positive effect on the amylase activity. Glutathione peroxidase (GPX) activity was highest in the group with 1.2 mg Se kg^-1 and lowest with the basal diet. The activity of catalase (CAT) was increased while glutathione reductase (GR) activity was decreased in response to the addition of Se. No significant interactive effects of Se and VE on the enzyme activities were found except superoxide dismutase (SOD) activity. While relative expressions of GPX, CAT, and SOD genes were significantly responsive to the addition of dietary Se, VE significantly promoted the gene expression of SOD. The results suggested that Se and VE might have beneficial effects on the growth and antioxidant responses of A. japonicus.

Selenomethionine Improves Mitochondrial Function by Upregulating Mitochondrial Selenoprotein in a Model of Alzheimer's Disease

Alzheimer’s disease (AD), the most common neurodegenerative disease in elderly humans, is pathologically characterized by amyloid plaques and neurofibrillary tangles. Mitochondrial dysfunction that occurs in the early stages of AD, which includes dysfunction in mitochondrial generation and energy metabolism, is considered to be closely associated with AD pathology. Selenomethionine (Se-Met) has been reported to improve cognitive impairment and reduce amyloid plaques and neurofibrillary tangles in 3xTg-AD mice. Whether Se-Met can regulate mitochondrial dysfunction in an AD model during this process remains unknown.In this study, the N2a-APP695-Swedish (N2aSW) cell and 8-month-old 3xTg-AD mice were treated with Se-Met in vitro and in vivo. Our study showed that the numbers of mitochondria were increased after treatment with Se-Met. Se-Met treatment also significantly increased the levels of NRF1 and Mfn2, and decreased those of OPA1 and Drp1. In addition, the mitochondrial membrane potential was significantly increased, while the ROS levels and apoptosis rate were significantly decreased, in cells after treatment with Se-Met. The levels of ATP, complex IV, and Cyt c and the activity of complex V were all significantly increased. Furthermore, the expression level of SELENO O was increased after Se-Met treatment. Thus, Se-Met can maintain mitochondrial dynamic balance, promote mitochondrial fusion or division, restore mitochondrial membrane potential, promote mitochondrial energy metabolism, inhibit intracellular ROS generation, and reduce apoptosis. These effects are most likely mediated via upregulation of SELENO O. In summary, Se-Met improves mitochondrial function by upregulating mitochondrial selenoprotein in these AD models.

Organic Selenium Increased Gilts Antioxidant Capacity, Immune Function, and Changed Intestinal Microbiota

Selenium is an indispensable essential micronutrient for humans and animals, and it can affect biological functions by combining into selenoproteins. The purpose of this study was to investigate the effects of 2-hydroxy-4-methylselenobutanoic acid (HMSeBA) on the antioxidant performance, immune function, and intestinal microbiota composition of gilts. From weaning to the 19th day after the second estrus, 36 gilts (Duroc × Landrace × Yorkshire) were assigned to three treatments: control group, sodium selenite group (0.3 mg Se/kg Na₂SeO₃), and HMSeBA group (0.3 mg Se/kg HMSeBA). Dietary supplementation with HMSeBA improved the gilts tissue selenium content (except in the thymus) and selenoprotein P (SelP1) concentration when compared to the Na₂SeO₃ or control group. Compared with the control group, the antioxidant enzyme activity in the tissues from gilts in the HMSeBA group was increased, and the concentration of malondialdehyde in the colon had a decreasing trend (p = 0.07). Gilts in the HMSeBA supplemented group had upregulated gene expression of GPX2, GPX4, and SelX in spleen tissue, TrxR1 in thymus; GPX1 and SelX in duodenum, GPX3 and SEPHS2 in jejunum, and GPX1 in the ileum tissues (p < 0.05). In addition, compared with the control group, the expression of interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), and monocyte chemotactic protein-1 (MCP-1) in the liver, spleen, thymus, duodenum, ileum, and jejunum of gilts in the HMSeBA group were downregulated (p < 0.05), while the expression of interleukin-10 (IL-10) and transforming growth factor-β (TGF-β) in the liver, thymus, jejunum, and ileum were upregulated (p < 0.05). Compared with the control group and the Na₂SeO₃ group, HMSeBA had increased concentration of serum cytokines interleukin-2 (IL-2) and immunoglobulin G (IgG; p < 0.05), increased concentration of intestinal immunoglobulin A (sIgA; p < 0.05), and decreased concentration of serum IL-6 (p < 0.05). Dietary supplementation with HMSeBA also increased the abundance of intestinal bacteria (Ruminococcaceae and Phascolarctobacterium; p < 0.05) and selectively inhibited the abundance of some bacteria (Parabacteroides and Prevotellaceae; p < 0.05). In short, HMSeBA improves the antioxidant performance and immune function of gilts, and changed the structure of the intestinal microflora. And this study provided data support for the application of HMSeBA in gilt and even pig production.

Revisiting the Effects of Different Dietary Sources of Selenium on the Health and Performance of Dairy Animals: a Review

Selenium (Se) is one of the most important essential trace elements in livestock production. It is a structural component in at least 25 selenoproteins such as the iodothyronine deiodinases and thioredoxin reductases as selenocysteine at critical positions in the active sites of these enzymes. It is also involved in the synthesis of the thyroid hormone and influences overall body metabolism. Selenium being a component of the glutathione peroxidase enzyme also plays a key role in the antioxidant defense system of animals. Dietary requirements of Se in dairy animals depend on physiological status, endogenous Se content, Se source, and route of administration. Most of the dietary Se is absorbed through the duodenum in ruminants and also some portion through the rumen wall. Inorganic Se salts such as Na-selenate and Na-selenite have shown lower bioavailability than organic and nano-Se. Selenium deficiency has been associated with reproductive disorders such as retained placenta, abortion, early embryonic death, and infertility, together with muscular diseases (like white muscle disease and skeletal and cardiac muscle necrosis). The deficiency of Se can also affect the udder health particularly favoring clinical and subclinical mastitis, along with an increase of milk somatic cell counts in dairy animals. However, excessive Se supplementation (5 to 8 mg/kg DM) can lead to acute toxicity including chronic and acute selenosis. Se is the most vital trace element for the optimum performance of dairy animals. This review focuses to provide insights into the comparative efficacy of different forms of dietary Se (inorganic, organic, and nano-Se) on the health and production of dairy animals and milk Se content.

Effects of Selenium on MAC-T Cells in Bovine Mastitis: Transcriptome Analysis of Exosomal mRNA Interactions

Selenium, a micronutrient, is indispensable for maintaining normal metabolic functions in animals and plants. Selenium has shown promise in terms of its effect on the immune function, ability to control inflammation, and ability to improve bovine mammary gland health. Bovine mastitis remains a major threat to dairy herds globally and has economically significant impacts. The exosomes are a new mode of intercellular communication. Exosomal transfer of mRNAs, microRNAs, and proteins between cells affects the protein production of recipient cells. The development of novel high-throughput omics approaches and bioinformatics tools will help us understand the effects of selenium on immunobiology. However, the differential expression of mRNAs in bovine mammary epithelial cell-derived exosomes has rarely been studied. In the present study, differences in the exosomal transcriptome between control and selenium-treated MAC-T cells were identified by RNA sequencing and transcriptome analysis. The results of mRNA profiling revealed 1978 genes in exosomes that were differentially expressed between the selenium-treated and control cells. We selected and analyzed 91 genes that are involved in inflammation, redox reactions, and immune cell function related to mastitis. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed enrichment pathways involved in selenoproteins and the Ras/PI3K/AKT, MAPK, and FOXO signaling pathways. Our results revealed that selenium may play a crucial role in immune and inflammatory regulation by influencing the differential expression of exosomal mRNAs of key genes in bovine mastitis.

Selenium Nanoparticles for Biomedical Applications: From Development and Characterization to Therapeutics

Selenium (Se) is an essential element to human health that can be obtained in nature through several sources. In the human body, it is incorporated into selenocysteine, an amino acid used to synthesize several selenoproteins, which have an active center usually dependent on the presence of Se. Although Se shows several beneficial properties in human health, it has also a narrow therapeutic window, and therefore the excessive intake of inorganic and organic Se-based compounds often leads to toxicity. Nanoparticles based on Se (SeNPs) are less toxic than inorganic and organic Se. They are both biocompatible and capable of effectively delivering combinations of payloads to specific cells following their functionalization with active targeting ligands. Herein, the main origin of Se intake, its role on the human body, and its primary biomedical applications are revised. Particular focus will be given to the main therapeutic targets that are explored for SeNPs in cancer therapies, discussing the different functionalization methodologies used to improve SeNPs stability, while enabling the extensive delivery of drug-loaded SeNP to tumor sites, thus avoiding off-target effects.

Selenium in Human Health and Gut Microflora: Bioavailability of Selenocompounds and Relationship With Diseases

This review covers current knowledge of selenium in the dietary intake, its bioavailability, metabolism, functions, biomarkers, supplementation and toxicity, as well as its relationship with diseases and gut microbiota specifically on the symbiotic relationship between gut microflora and selenium status. Selenium is essential for the maintenance of the immune system, conversion of thyroid hormones, protection against the harmful action of heavy metals and xenobiotics as well as for the reduction of the risk of chronic diseases. Selenium is able to balance the microbial flora avoiding health damage associated with dysbiosis. Experimental studies have shown that inorganic and organic selenocompounds are metabolized to selenomethionine and incorporated by bacteria from the gut microflora, therefore highlighting their role in improving the bioavailability of selenocompounds. Dietary selenium can affect the gut microbial colonization, which in turn influences the host's selenium status and expression of selenoproteoma. Selenium deficiency may result in a phenotype of gut microbiota that is more susceptible to cancer, thyroid dysfunctions, inflammatory bowel disease, and cardiovascular disorders. Although the host and gut microbiota benefit each other from their symbiotic relationship, they may become competitors if the supply of micronutrients is limited. Intestinal bacteria can remove selenium from the host resulting in two to three times lower levels of host's selenoproteins under selenium-limiting conditions. There are still gaps in whether these consequences are unfavorable to humans and animals or whether the daily intake of selenium is also adapted to meet the needs of the bacteria.

Delivery of selenium using chitosan nanoparticles: Synthesis, characterization, and antioxidant and growth effects in Nile tilapia (Orechromis niloticus)

This study aimed to elucidate the effects of selenium-loaded chitosan nanoparticles used as a dietary supplement on Nile tilapia (Oreochromis niloticus) antioxidant and growth responses. First, chitosan-based nanoparticles containing selenium (Se) were synthesized using the ionotropic gelation method and their physicochemical characteristics, controlled release profile, and antioxidant activity properties were investigated. Thereafter, the effects on glutathione peroxidase and antioxidant activities (by radical scavenging activity), growth, and whole-body composition of Nile tilapia were evaluated when they were fed with Se-loaded chitosan nanoparticles and compared with other selenium dietary supplements. Se-loaded chitosan nanoparticles showed high entrapment efficiency (87%), spherical shape, smooth surface, and broad size distribution. The controlled release of Se consisted of an initial burst followed by a gradual release over 48 h. Se-loaded nanoparticles presented significantly higher antioxidant activity compared to free Se. A 60-day feeding trial was conducted to compare the effects of supplementing different dietary Se sources, including selenomethionine (as organic source), sodium selenite (as inorganic source), and Se-loaded chitosan nanoparticles (Se-Nano and Se-Nano x1.5) on antioxidant and growth responses of Nile tilapia. A basal diet without Se supplementation was used as the control. The dietary supplementations with different Se sources (free and encapsulated selenium) lead to significant improvements in final weight and feed efficiency of Nile tilapia fingerlings. However, dietary treatments did not affect whole-body protein and lipid content. Diets containing Se-Nano and Se-Nano x1.5 were more effective than sodium selenite and selenomethionine in preventing oxidative stress and improving antioxidant activity in Nile tilapia. Overall, Se-loaded nanoparticles presented a great potential as an efficient source for delivering dietary Se to Nile tilapia, directly affecting the growth performance, feed efficiency, oxidative stress, and antioxidant activity of this species.

Juvenile Selenium Deficiency Impairs Cognition, Sensorimotor Gating, and Energy Homeostasis in Mice

Selenium (Se) is an essential micronutrient of critical importance to mammalian life. Its biological effects are primarily mediated via co-translational incorporation into selenoproteins, as the unique amino acid, selenocysteine. These proteins play fundamental roles in redox signaling and includes the glutathione peroxidases and thioredoxin reductases. Environmental distribution of Se varies considerably worldwide, with concomitant effects on Se status in humans and animals. Dietary Se intake within a narrow range optimizes the activity of Se-dependent antioxidant enzymes, whereas both Se-deficiency and Se-excess can adversely impact health. Se-deficiency affects a significant proportion of the world's population, with hypothyroidism, cardiomyopathy, reduced immunity, and impaired cognition being common symptoms. Although relatively less prevalent, Se-excess can also have detrimental consequences and has been implicated in promoting both metabolic and neurodegenerative disease in humans. Herein, we sought to comprehensively assess the developmental effects of both Se-deficiency and Se-excess on a battery of neurobehavioral and metabolic tests in mice. Se-deficiency elicited deficits in cognition, altered sensorimotor gating, and increased adiposity, while Se-excess was surprisingly beneficial.

Advances in Research on the Toxicological Effects of Selenium

Selenium is a trace element necessary for the growth of organisms. Moreover, selenium supplementation can improve the immunity and fertility of the body, as well as its ability to resist oxidation, tumors, heavy metals, and pathogenic microorganisms. However, owing to the duality of selenium, excessive selenium supplementation can cause certain toxic effects on the growth and development of the body and may even result in death in severe cases. At present, increasing attention is being paid to the development and utilization of selenium as a micronutrient, but its potential toxicity tends to be neglected. This study systematically reviews recent research on the toxicological effects of selenium, aiming to provide theoretical references for selenium toxicology-related research and theoretical support for the development of selenium-containing drugs, selenium-enriched dietary supplements, and selenium-enriched foods.

Roles of Selenoproteins in Brain Function and the Potential Mechanism of Selenium in Alzheimer's Disease

Selenium (Se) and its compounds have been reported to have great potential in the prevention and treatment of Alzheimer's disease (AD). However, little is known about the functional mechanism of Se in these processes, limiting its further clinical application. Se exerts its biological functions mainly through selenoproteins, which play vital roles in maintaining optimal brain function. Therefore, selenoproteins, especially brain function-associated selenoproteins, may be involved in the pathogenesis of AD. Here, we analyze the expression and distribution of 25 selenoproteins in the brain and summarize the relationships between selenoproteins and brain function by reviewing recent literature and information contained in relevant databases to identify selenoproteins (GPX4, SELENOP, SELENOK, SELENOT, GPX1, SELENOM, SELENOS, and SELENOW) that are highly expressed specifically in AD-related brain regions and closely associated with brain function. Finally, the potential functions of these selenoproteins in AD are discussed, for example, the function of GPX4 in ferroptosis and the effects of the endoplasmic reticulum (ER)-resident protein SELENOK on Ca²⁺ homeostasis and receptor-mediated synaptic functions. This review discusses selenoproteins that are closely associated with brain function and the relevant pathways of their involvement in AD pathology to provide new directions for research on the mechanism of Se in AD.

Long-term effect of parental selenium supplementation on the one-carbon metabolism in rainbow trout (Oncorhynchus mykiss) fry exposed to hypoxic stress

This study evaluated how different forms of selenium (Se) supplementation into rainbow trout broodstock diets modified the one-carbon metabolism of the progeny after the beginning of exogenous feeding and followed by hypoxia challenge. The progeny of three groups of rainbow trout broodstock fed either a control diet (Se level: 0·3 µg/g) or a diet supplemented with inorganic sodium selenite (Se level: 0·6 µg/g) or organic hydroxy-selenomethionine (Se level: 0·6 µg/g) was cross-fed with diets of similar Se composition for 11 weeks. Offspring were sampled either before or after being subjected to an acute hypoxic stress (1·7 mg/l dissolved oxygen) for 30 min. In normoxic fry, parental Se supplementation allowed higher glutathione levels compared with fry originating from parents fed the control diet. Parental hydroxy-selenomethionine treatment also increased cysteine and cysteinyl-glycine concentrations in fry. Dietary Se supplementation decreased glutamate-cysteine ligase (cgl) mRNA levels. Hydroxy-selenomethionine feeding also lowered the levels of some essential free amino acids in muscle tissue. Supplementation of organic Se to parents and fry reduced betaine-homocysteine S-methyltransferase (bhmt) expression in fry. The hypoxic stress decreased whole-body homocysteine, cysteine, cysteinyl-glycine and glutathione levels. Together with the higher mRNA levels of cystathionine beta-synthase (cbs), a transsulphuration enzyme, this suggests that under hypoxia, glutathione synthesis through transsulphuration might have been impaired by depletion of a glutathione precursor. In stressed fry, S-adenosylmethionine levels were significantly decreased, but S-adenosylhomocysteine remained stable. Decreased bhmt and adenosylmethionine decarboxylase 1a (amd1a) mRNA levels in stressed fry suggest a nutritional programming by parental Se also on methionine metabolism of rainbow trout.

Co-application of Se and a biostimulant at different wheat growth stages: Influence on grain development

An appropriate selenium intake can be beneficial for human health. Se-biofortified food in Se-deficient regions is becoming an increasingly common practice but there are still issues to be addressed regarding the observed Se-induced toxicity to the plant. In this respect, plant biostimulants are used to enhance nutrition efficiency, abiotic stress tolerance and crop quality. In this work, the efficacy of a plant biostimulant to counteract the Se-induced stress in wheat plants is experimentally assessed. The co-application of different Se-biofortification treatments and the biostimulant at different growth stages (tillering or heading stage) was investigated. The use of micro focused X-ray spectroscopy allows us to confirm organic Se species to be the main Se species found in wheat grain and that the proportion of organic Se species is only slightly affected by the Se application stage. Our study proves that the biostimulant had a key role in the enhancement of both the amount of grains produced per spike and their dry biomass without hindering Se enrichment process, neither diminishing the Se concentration nor massively disrupting the Se species present. This information will be useful to minimize both plant toxicity and economic cost towards a more effective and plant healthy selenium supplementation.

Biochemical metal accumulation effects and metalloprotein metal detoxification in environmentally exposed tropical Perna perna mussels

Marine bivalves have been widely applied as environmental contamination bioindicators, although studies concerning tropical species are less available compared to temperate climate species. Assessments regarding Perna perna mytilid mussels, in particular, are scarce, even though this is an extremely important species in economic terms in tropical countries, such as Brazil. To this end, Perna perna mytilids were sampled from two tropical bays in Southeastern Brazil, one anthropogenically impacted and one previously considered a reference site for metal contamination. Gill metallothionein (MT), reduced glutathione (GSH), carboxylesterase (CarbE) and lipid peroxidation (LPO) were determined by UV-vis spectrophotometry, and metal and metalloid contents were determined by inductively coupled plasma mass spectrometry (ICP-MS). Metalloprotein metal detoxification routes in heat-stable cellular gill fractions were assessed by size exclusion high performance chromatography (SEC-HPLC) coupled to an ICP-MS. Several associations between metals and oxidative stress endpoints were observed at all four sampling sites through a Principal Component Analysis. As, Cd, Ni and Se contents, in particular, seem to directly affect CarbE activity. MT is implicated in playing a dual role in both metal detoxification and radical oxygen species scavenging. Differential SEC-HPLC-ICP-MS metal-binding profiles, and, thus, detoxification mechanisms, were observed, with probable As-, Cu- and Ni-GSH complexation and binding to low molecular weight proteins. Perna perna mussels were proven adequate tropical bioindicators, and further monitoring efforts are recommended, due to lack of data regarding biochemical metal effects in tropical species. Integrated assessments, as performed herein demonstrate, are invaluable in evaluating contaminated aquatic environments, resulting in more accurate ecological risk assessments.

Histopathological assessment of protective effects of selenium nanoparticles on rat hepatocytes exposed to Gamma radiation

Gamma radiation are used in many medical and technical applications, however, it is one of the most dangerous kinds of radiation and can be harmful to the body. The present study was designed to clarify the protective effects of the selenium supplementation as selenium nanoparticle and selenite selenium in rat liver against Gamma irradiation with different intensities of 2.00 and 8.00 Gy. A total number of 45 healthy male Wistar rats were randomly divided into nine groups of five each. The radiation procedure was carried out in the Cobalt 60 equipment in Omid hospital, Urmia. The animals were simultaneously immobilized in a transparent acrylic plate and exposed to different intensities of 2.00 and 8.00 Gy radiations on day 7th and 14th of the experiment. After 72 hr after the last radiation, the animals were euthanized, and blood and liver tissue were collected. Histological analyses revealed the radiation-induced hepatic injury in rats, which included vacuolated cytoplasm, liver necrosis, fibrosis, and vascular lesions followed by a significant increase in alanine transaminase, alanine transaminase, alkaline phosphatase, and Gamma-glutamyl transferase. Selenium nanoparticles bear a more potent antioxidant effect in comparison with selenium selenite and can effectively protect the liver cell against Gamma radiation at a dose of 8.00 Gy.

The mixed application of organic and inorganic selenium shows better effects on incubation and progeny parameters

This experiment aims to study the effects of dietary selenium (Se) sources on the production performance, reproductive performance, and maternal effect of breeder laying hens. A total of 2,112 Hyline brown breeder laying hens of 42 wk of age were selected and randomly divided into 3 groups, with 8 repeats in each group and 88 chickens per repeat. The sources of dietary Se were sodium selenite (SS, added at 0.3 mg/kg), L-selenomethionine (L-SM, added at 0.2 mg/kg), and combination of SS and L-SM (SS 0.15 mg/kg + L-SM 0.15 mg/kg). The pretest period was 7 d, and the breeding period was 49 d. Compared with 0.3 mg/kg SS, the addition of 0.2 mg/kg L-SM in the diet significantly increased the hatchability (P < 0.05) and the Se content (P < 0.05) in egg yolk and chicken embryo tissues and improved the activity of yolk glutathione peroxidase (GSH-px) effectively (P < 0.05). Treatment with 0.2 mg/kg L-SM also reduced the content of yolk malondialdehyde (P < 0.05) and significantly improved the antioxidant performance of 1-day-old chicks, as manifested by increased activity of antioxidant enzymes (GSH-px, total antioxidant capacity and the ability to inhibit hydroxyl radicals) in serum, pectoral, heart, and liver (P < 0.05). This treatment decreased the malondialdehyde content (P < 0.05) and increased the expression of liver glutathione peroxidase 4 and deiodinase 1 mRNA (P < 0.05). Adding L-SM to the diets of chickens increased the hatchability of breeder eggs as well as the amount of Se deposited and antioxidant enzyme activity in breeder eggs and embryos. Compared with SS, L-SM was more effectively transferred from the mother to the embryo and offspring, showing efficient maternal nutrition. For breeder diets, the combination of organic and inorganic Se (0.15 mg/kg SS + 0.15 mg/kg L-SM) is an effective nutrient supplementation technology program for effectively improving the breeding performance of breeders and the antioxidant performance and health level of offspring chicks.

Dietary supplementation with selenium-enriched earthworm powder improves antioxidative ability and immunity of laying hens

Selenium (Se) has been recognized as an essential dietary nutrient for decades, and organic Se sources rather than inorganic ones are increasingly advocated as Se supplements. Earthworms have been studied as a feed additive and animal protein source for many yr. The aim of this study was to evaluate the effect of Se-enriched earthworm powder (SEP) on the antioxidative ability and immunity of laying hens. A total of 120 27-wk-old laying hens were randomly divided into 4 groups (30 hens per group). Laying hens were fed diets supplemented with SEP having 0, 0.5, or 1 mg/kg of Se or with earthworm powder alone. After 5 wk of supplementation, serum from the hens was tested for nutritional components (protein, globulin, albumin, triglycerides, total cholesterol, and glucose), antioxidative properties (glutathione peroxidase, superoxide dismutase, catalase, and nitric oxide), and immune responses (lysozymes, immunoglobulin G, IL-2, and interferon gamma). We found that SEP with 1.0 mg/kg of Se upregulated the hens' total protein, albumin, glutathione peroxidase, superoxide dismutase, IgG, and IL-2 and downregulated triglycerides, total cholesterol, glucose, and nitric oxide. These results indicate that SEP improves antioxidative levels and immune function of laying hens, indicating potential benefit from use of SEP as a feed additive in the poultry industry.

Selenoneine Ameliorates Hepatocellular Injury and Hepatic Steatosis in a Mouse Model of NAFLD

Selenoneine is a novel organic selenium compound markedly found in the blood, muscles, and other tissues of fish. This study aimed to determine whether selenoneine attenuates hepatocellular injury and hepatic steatosis in a mouse model of non-alcoholic fatty liver disease (NAFLD). Mice lacking farnesoid X receptor (FXR) were used as a model for fatty liver disease, because they exhibited hepatomegaly, hepatic steatosis, and hepatic inflammation. Fxr-null mice were fed a 0.3 mg Se/kg selenoneine-containing diet for four months. Significant decreases in the levels of hepatomegaly, hepatic damage-associated diagnostic markers, hepatic triglycerides, and total bile acids were found in Fxr-null mice fed with a selenoneine-rich diet. Hepatic and blood clot total selenium concentrations were 1.7 and 1.9 times higher in the selenoneine group than in the control group. A marked accumulation of selenoneine was found in the liver and blood clot of the selenoneine group. The expression levels of oxidative stress-related genes (heme oxygenase 1 (Hmox1), glutathione S-transferase alpha 1 (Gsta1), and Gsta2), fatty acid synthetic genes (stearoyl CoA desaturase 1(Scd1) and acetyl-CoA carboxylase 1 (Acc1)), and selenoprotein (glutathione peroxidase 1 (Gpx1) and selenoprotein P (Selenop)) were significantly decreased in the selenoneine group. These results suggest that selenoneine attenuates hepatic steatosis and hepatocellular injury in an NAFLD mouse model.

Selenium-Ethylene Interplay in Postharvest Life of Cut Flowers

Selenium (Se) is considered a beneficial element in higher plants when provided at low concentrations. Recently, studies have unveiled the interactions between Se and ethylene metabolism throughout plant growth and development. However, despite the evidence that Se may provide longer shelf life in ethylene-sensitive flowers, its primary action on ethylene biosynthesis and cause-effect responses are still understated. In the present review, we discuss the likely action of Se on ethylene biosynthesis and its consequence on postharvest physiology of cut flowers. By combining Se chemical properties with a dissection of ethylene metabolism, we further highlighted both the potential use of Se solutions and their downstream responses. We believe that this report will provide the foundation for the hypothesis that Se plays a key role in the postharvest longevity of ethylene-sensitive flowers.

Effect of Dietary Selenium Supplementation on Growth and Reproduction of Silkworm Bombyx mori L

The effects of selenium (Se) on the growth and reproduction of the Lepidoptera insect, the silkworm, Bombyx mori L were investigated. Initially, the silkworms were divided into eight groups (150 larvae/group) on the basis of feeding with mulberry leaves saturated with different concentrations of Se (25, 50, 100, 125, 150, 175, and 200 μM) and control from the first day of the fourth instar larvae. After feeding, growth and reproductive performance of B. mori L. were investigated with standard techniques used in sericulture. After the data analysis, 50 μM of Se was recognized as the optimal level which positively influenced the growth and production, with prolonged stage of larvae, increased larval, cocoon, and pupal weights, and enhanced number of eggs laid by the female moth as compared to the control group. On the contrary, 200 μM of Se treatment displayed toxic to silkworm and induced significant decrease in the growth, cocoon production, and reproduction. The weight of the cocoon shell, the cocoon shell ratio, number of eggs produced, and fertilization ratio in all the Se-treated groups were lower than the control group. The present study indicated that lower levels of (50 μM) of Se can promote the larval and pupal growth of the B. mori L. resulting in the higher yield of cocoon crop and significantly influencing the fecundity, while high concentration was toxic to silkworm. Our data supply the novel application of Se which could be highly beneficial to sericulture farmers.

Selenium Supplementation and Prostate Health in a New Zealand Cohort

Background: There is variable reporting on the benefits of a 200 μg/d selenium supplementation towards reducing prostate cancer impacts. The current analysis is to understand whether stratified groups receive supplementation benefits on prostate health. Methods: 572 men were supplemented with 200 µg/d selenium as selinized yeast for six months, and 481 completed the protocol. Selenium and prostate-specific antigen (PSA) levels were measured in serum at pre- and post-supplementation. Changes in selenium and PSA levels subsequent to supplementation were assessed with and without demographic, lifestyle, genetic and dietary stratifications. Results: The post-supplementation selenium (p = 0.002) and the gain in selenium (p < 0.0001) by supplementation were significantly dependent on the baseline selenium level. Overall, there was no significant correlation between changes in PSA and changes in selenium levels by supplementation. However, stratified analyses showed a significant inverse correlation between changes in PSA and changes in selenium in men below the median age (p = 0.048), never-smokers (p = 0.031), men carrying the GPX1 rs1050450 T allele (CT, p = 0.022 and TT, p = 0.011), dietary intakes above the recommended daily intake (RDI) for zinc (p < 0.05), and below the RDI for vitamin B12 (p < 0.001). Conclusions: The current analysis shows the influence of life factors on prostate health benefits of supplemental selenium.

Selenium and cadmium in bioaccessible fraction of organic weaning food: Risk assessment and influence of dietary components

BACKGROUND

The tendency of some sectors of the population to consume organic food has also come to include baby food. Nevertheless, it is necessary to develop studies to support the true nutritional and toxicological value of these products, making special emphasis in several trace elements. To our knowledge, no studies have been conducted on this type of organic food.

METHODS

Weaning foods with different formulations categorized as organic were analyzed to determine Se and Cd contents as well as its bioaccesibility. The analyses were conducted by electro thermal atomic absorption spectroscopy (ET - AAS) after the treatment of the samples with acid mineralization. Besides, macronutrient analyses (protein, fat and dietary fiber) were also developed. Finally, a novelty statistic approach such as @Risk was used to evaluate contributions to DRI or PTWI of Se and Cd derived for consumption of these weaning foods.

RESULTS

Se content ranged between 2.44-15.4 μg Kg ¹. Samples with meat ingredients showed the highest Se contents, while weaning foods consisting of fruits or vegetables presented the lowest concentrations. Se bioccessible concentration ranged between 1.90-4.35 μg Kg^-1 with a greater uniformity amongst analyzed samples. Regarding Cd, concentrations of this heavy metal ranged between 1.23 and 3.64 μg Kg^-1. Furthermore, Cd bioaccessibility of organic weaning foods ranged between 0.17 and 1.38 μg Kg^-1. The solubility of all samples studied was around 20% from the initial Cd concentration. A negative statistical correlation between fat content - Cd bioaccesible (p < 0.05; r = - 0.756) and Cd content - Se bioaccesible (p < 0.05; r = - 0.777) were also found.

CONCLUSIONS

Cd concentrations are considerably lower than those reported in weaning formulas which were not categorized as organic. On the other hand, the analysed organic jars did not represent a significant source of Se. The probabilistic assessment developed, showed that contributions to DRI of Se for infants 1-3 years old by consumption of these weaning foods, are excessively low (15% at best).

Selenium as a Protective Agent Against Pests: A Review

The aim of the present review is to summarize selenium's connection to pests. Phytopharmaceuticals for pest control, which increase the pollution in the environment, are still widely used nowadays regardless of their negative characteristics. The use of trace elements, including selenium, can be an alternative method of pest control. Selenium can repel pests, reduce their growth, or cause toxic effects while having a positive effect on the growth of plants. In conclusion, accumulated selenium protects plants against aphids, weevils, cabbage loopers, cabbage root flies, beetles, caterpillars, and crickets due to both deterrence and toxicity.

Trace minerals in tilapia fillets: Status in the United States marketplace and selenium supplementation strategy for improving consumer's health

This goal of this study was to highlight the importance of minerals in the diet of fish for meeting micronutrient requirements in the human diet. First arsenic, calcium, cadmium, copper, iron, molybdenum, magnesium, manganese, sodium, phosphorus, potassium, selenium, and zinc concentrations of twelve commercially available tilapia samples were measured. The nutritional value of fillets in regard to their mineral content were assessed to establish potential health benefits or risks for consumers. The health benefit value of selenium was also calculated. Positive health benefit values indicate that tilapia fillets in the United States marketplace of this study do not pose health risks associated with mercury exposures. Selenium was the trace mineral of interest. After the market study, a seven-week fish feeding trial was conducted to study the influence of organic versus inorganic dietary selenium on Nile tilapia (Oreochromis niloticus). Fish were fed two different diets enriched with the same concentration (0.01g kg-1) of selenium in form of inorganic (sodium selenite) or organic (seleno-L-methionine) selenium in triplicate groups. There were no significant differences between growth and biometrics of fish fed different diets (p>0.05). At the end of trial twelve fish from each treatment were collected. Fillets of fish fed organic selenium had selenium concentrations of 0.55 ± 0.01 μg g-1 which were significantly (p<0.05) higher than fish fed inorganic selenium at levels of 0.22 ± 0.008 μg g-1 or fish samples from the marketplace with a selenium level of 0.2 ± 0.03 μg g-1. Fish fed organic selenium also had significantly higher (p<0.05) plasma and kidney selenium in comparison to fish fed inorganic selenium. No significant differences (p>0.05) were observed in glutathione peroxidase activities in either the plasma or liver of Nile tilapia in the different treatment groups. This study shows that organic selenium is a better option for production of Nile tilapia fillets rich in selenium.

Comparison of the effects of selenomethionine and selenium-enriched yeast in the triple-transgenic mouse model of Alzheimer's disease

Alzheimer's disease (AD) is a complex, multifactorial neurodegenerative disease that exhibits multiple pathogeneses and heterogeneity. Selenium (Se) is an essential trace element for human and animal nutrition. It has been shown that supplementation with two organic forms of Se, Se-enriched yeast (Se-yeast) and selenomethionine (Se-Met), could improve cognitive impairment, reverse synaptic deficits and mitigate tau pathology in triple-transgenic (3× Tg) AD mice. Se-yeast is well known for its high Se-Met content, which may mediate its anti-AD effects. In addition, a large amount of the physiological and biochemical mechanisms of these two Se drugs in the amelioration AD pathology remains unknown. In this study, the content of Se-yeast aside from Se was analyzed, and the effects of Se-Met and Se-yeast on 3× Tg-AD mice were investigated and compared. The results showed that both Se-Met and Se-yeast not only significantly increased the Se levels, enhanced the antioxidant capacity and improved the cognitive decline in the model, but also decreased the Aβ and tau pathologies in the brain tissue of the AD mice. Moreover, the ability of Se-Met to increase the Se levels in different tissues of the AD mice was more significant than that of Se-yeast. However, the positive effect of Se-yeast on improving the cognitive ability of the AD mice was better than that of Se-Met, likely due to the various elements, vitamins and other nutrients in Se-yeast. Collectively, these results suggest that Se-yeast has potential as a clinical health product or drug for AD but that Se-Met, as a pure organic Se compound, is more suitable for studying the therapeutic mechanism of Se because of its comprehensive effects on AD.

High status of mercury and selenium in false killer whales (Pseudorca crassidens, Owen 1846) stranded on Southern South America: A possible toxicological concern?

The study was carried out to determine Hg and Se concentrations in false killer whales stranded on the Estrecho de Magallanes, Chile, South America. Tissue samples of five mature specimens were analyzed (two females and three males). Mean Hg concentration in liver 1068 (234) μg g^-1 dry weight (DW) (standard deviation in parenthesis) was markedly higher than those in kidney 272 (152) μg g^-1 DW, lung 423 (325) μg g^-1 DW, spleen 725 (696) μg g^-1 DW, muscle 118 (94) μg g^-1 DW and testicle 18.0 (2.8) μg g^-1 DW. Mean Se concentration in liver, 398 (75) μg g^-1 DW, was higher than those in kidney 162 (69) μg g^-1 DW, lung 128 (84) μg g^-1 DW, spleen 268 (245) μg g^-1 DW, muscle 47 (38) μg g^-1 DW and testicle 25.4 (2.1) μg g^-1 DW. Positive correlations were found between Hg and Se molar concentrations in muscle, lung, spleen and kidney. Molar ratio of Se/Hg in liver, lung and muscle were <1, but those in kidney and testicle were markedly >1 suggesting a Se protection against Hg toxicity. In all the examined specimens Hg values exceeded the toxic thresholds defined for hepatic damage in marine mammals, with Se/Hg molar ratios below 1 implying limited protective action of Se. Generally, our results showed that individuals are carrying a significant burden, reflecting a high exposure to this toxic metal. This constitutes the first report on Hg and Se levels for a large subantarctic odontocete in South America region, providing insights into their contamination status and with information to the understanding of possible impacts on wild populations.

Bioaccessible selenium sourced from Se-rich mustard cake facilitates protection from TBHP induced cytotoxicity in melanoma cells

Selenium (Se) is an essential dietary supplement that resolves inflammatory responses and offers antioxidant cytoprotection. In this study, we present the data on the cytoprotective effect of Se-rich mustard protein isolated from mustard cultivated in seleniferous soils in Punjab, India. The concentrations of total Se in mustard seed, oil-free mustard cake, and mustard protein were 110.0 ± 3.04, 143.0 ± 5.18, and 582.3 ± 6.23 μg g-1, respectively. The cytoprotective effect of Se-rich mustard protein was studied on tert-butyl hydroperoxide (TBHP)-induced cytotoxicity in a mouse melanoma cell line (B16-F10). When compared with TBHP treated cells (where no viable cells were found), Se-rich protein made bioaccessible through simulated gastrointestinal digestion protected melanoma cells from cytotoxicity with decreased levels of oxidative stress resulting in 73% cell viability. Such an effect was associated with a significant increase in glutathione peroxidase activity as a function of bioaccessible Se and its response towards cytoprotection.

Metabolic syndrome and selenium in fetal programming: gender differences

OBJECTIVES

Since Selenium (Se) forms part of glutathione peroxidase (GPx), which appears to have a dual role in Metabolic Syndrome (MS), this study evaluates the implication of Se in the transmission of this pathology to the progeny.

METHODS

Se body distribution, glucose, triglycerides, cholesterol, insulin and metabolic hormones [glucagon, leptin, gastric inhibitory polypeptide (GIP), and triiodothyronine (T3)], growth factors, receptor activator of nuclear factor kappa-B ligand (RANK-L) and osteopontin, as well as oxidative hepatic balance in the offspring of dams exposed to a fructose-rich diet (65%) with normal Se content (0.01 ppm) during gestation and lactation, were measured according to sex.

RESULTS

Fructose pups had lower body weight; however, male pups had a lower body mass index and growth indicators in serum. Fructose pups, especially females, had lower levels of serum insulin and HOMA-IR. With regard to Se homeostasis, fructose pups presented a depletion of Se in heart and muscle, and repletion in kidneys, pancreas and thyroid, although only female pups showed a repletion of Se in the liver. Fructose pups presented lower superoxide dismutase activity and only female fructose pups had higher GPx activity, which provoked hepatic oxidation.

CONCLUSIONS

Se balance and Se tissue deposits in MS pups during lactation are altered by gender. This difference is focused on hepatic Se deposits that affect GPx activity, which could be related to a disruption in the insulin-signaling cascade in females. Furthermore, although female fructose pups had greater metabolic disorders, only the males' growth and development were affected. Particularly relevant is the depletion of Se found in the heart of fructose pups, as this element is essential for correct heart function.

Biofortified Crops Generated by Breeding, Agronomy, and Transgenic Approaches Are Improving Lives of Millions of People around the World

Biofortification is an upcoming, promising, cost-effective, and sustainable technique of delivering micronutrients to a population that has limited access to diverse diets and other micronutrient interventions. Unfortunately, major food crops are poor sources of micronutrients required for normal human growth. The manuscript deals in all aspects of crop biofortification which includes-breeding, agronomy, and genetic modification. It tries to summarize all the biofortification research that has been conducted on different crops. Success stories of biofortification include lysine and tryptophan rich quality protein maize (World food prize 2000), Vitamin A rich orange sweet potato (World food prize 2016); generated by crop breeding, oleic acid, and stearidonic acid soybean enrichment; through genetic transformation and selenium, iodine, and zinc supplementation. The biofortified food crops, especially cereals, legumes, vegetables, and fruits, are providing sufficient levels of micronutrients to targeted populations. Although a greater emphasis is being laid on transgenic research, the success rate and acceptability of breeding is much higher. Besides the challenges biofortified crops hold a bright future to address the malnutrition challenge.

Selenium Homeostasis and Clustering of Cardiovascular Risk Factors: A Systematic Review

Selenium is a trace element required for a range of cellular functions. It is widely used for the biosynthesis of the unique amino acid selenocysteine [Sec], which is a structural element of selenoproteins. This systematic review focused on the possible relation between selenium and metabolic risk factors. The literature was searched via PubMed, Scopus, ISI Web of Science, and Google Scholar. Searches were not restricted by time or language. Relevant studies were selected in three phases. After an initial quality assessment, two reviewers extracted all the relevant data, whereas the third reviewer checked their extracted data. All evidence came from experimental and laboratory studies. Selenoprotein P is the best indicator for selenium nutritional levels. In addition, high levels of selenium may increase the risk of metabolic syndrome while the lack of sufficient selenium may also promote metabolic syndrome. selenium supplementation in subjects with sufficient serum selenium levels has a contrary effect on blood pressure, LDL, and total cholesterol. According to the bioavailability of different types of selenium supplementation such as selenomethionine, selenite and selenium-yeast, it seems that the best nutritional type of selenium is selenium-yeast. Regarding obtained results of longitudinal studies and randomized controlled trials, selenium supplementation should not be recommended for primary or secondary cardio-metabolic risk prevention in populations with adequate selenium status.

Systematic review and meta-analysis shows a specific micronutrient profile in people with Down Syndrome: Lower blood calcium, selenium and zinc, higher red blood cell copper and zinc, and higher salivary calcium and sodium

Different metabolic profiles as well as comorbidities are common in people with Down Syndrome (DS). Therefore it is relevant to know whether micronutrient levels in people with DS are also different. This systematic review was designed to review the literature on micronutrient levels in people with DS compared to age and sex-matched controls without DS. We identified sixty nine studies from January 1967 to April 2016 through main electronic medical databases PubMed, Scopus, and Web of knowledge. We carried out meta-analysis of the data on four essential trace elements (Cu, Fe, Se, and Zn), six minerals (Ca, Cl, K, Mg, Na, and P), and five vitamins (vitamin A, B9, B12, D, and E). People with DS showed lower blood levels of Ca (standard mean difference (SMD) = -0.63; 95% confidence interval (CI): -1.16 to -0.09), Se (SMD = -0.99; 95% CI: -1.55 to -0.43), and Zn (SMD = -1.30; 95% CI: -1.75 to -0.84), while red cell levels of Zn (SMD = 1.88; 95% CI: 0.48 to 3.28) and Cu (SMD = 2.77; 95% CI: 1.96 to 3.57) were higher. They had also higher salivary levels of Ca (SMD = 0.85; 95% CI: 0.38 to 1.33) and Na (SMD = 1.04; 95% CI: 0.39 to 1.69). Our findings that micronutrient levels are different in people with DS raise the question whether these differences are related to the different metabolic profiles, the common comorbidities or merely reflect DS.

Antioxidant capacities of the selenium nanoparticles stabilized by chitosan

Backgrounds

Selenium (Se) as one of the essential trace elements for human plays an important role in the oxidation reduction system. But the high toxicity of Se limits its application. In this case, the element Se with zero oxidation state (Se⁰) has captured our attention because of its low toxicity and excellent bioavailability. However, Se⁰ is very unstable and easily changes into the inactive form. By now many efforts have been done to protect its stability. And this work was conducted to explore the antioxidant capacities of the stable Se⁰ nanoparticles (SeNPs) stabilized using chitosan (CS) with different molecular weights (Mws) (CS-SeNPs).

Results

The different Mws CS-SeNPs could form uniform sphere particles with a size of about 103 nm after 30 days. The antioxidant tests of the DPPH, ABTS, and lipid peroxide models showed that these CS-SeNPs could scavenge free radicals at different levels. And the 1 month old SeNPs held the higher ABTS scavenging ability that the value could reach up to 87.45 ± 7.63% and 89.44 ± 5.03% of CS(l)-SeNPs and CS(h)-SeNPs, respectively. In the cell test using BABLC-3T3 or Caco-2, the production of the intracellular reactive oxygen species (ROS) could be inhibited in a Se concentration-dependent manner. The topical or oral administration of CS-SeNPs, particularly the Se nanoparticles stabilized with low molecular weight CS, CS(l)-SeNPs, and treated with a 30-day storage process, could efficiently protect glutathione peroxidase (GPx) activity and prevent the lipofusin formation induced by UV-radiation or d-galactose in mice, respectively. Such effects were more evident in viscera than in skin. The acute toxicity of CS(l)-SeNPs was tenfold lower than that of H₂SeO₃.

Conclusions

Our work could demonstrate the CS-SeNPs hold a lower toxicity and a 30-day storage process could enhance the antioxidant capacities. All CS-SeNPs could penetrate the tissues and perform their antioxidant effects, especially the CS(l)-SeNPs in mice models. What’s more, the antioxidant capacities of CS-SeNPs were more evident in viscera than in skin.

Organic selenium in animal nutrition – utilisation, metabolism, storage and comparison with other selenium sources

The importance of selenium as a key component of antioxidant systems in animals is well recognised due to much research about this mineral in many species. Selenium is required as part of the antioxidant enzyme structure and plays a major role in various protective systems in animal physiology, including immunity, cellular stability and DNA protection. The following review is the first in a series of three which details the importance of selenium in animal nutrition, and how the chemically organic form, which is akin to the form of the mineral in natural feed materials, can provide increased benefits in utilisation, storage and metabolism compared to inorganic sources.