Nutritional Se Research Articles

Alleviation of cadmium toxicity in soybean (Glycine max L.): Up-regulating antioxidant capacity and enzyme gene expressions and down-regulating cadmium uptake by organic or inorganic selenium

Although much interest has been focused on the role of selenium (Se) in plant nutrition over the last 20 years, the influences of organic selenium (selenomethionine; Se-Met) and inorganic selenium (potassium selenite; Se-K) on the growth and physiological characters of cadmium (Cd)-stressed Glycine max L.) seedlings have not yet been studied. In this study, the impacts of Se-Met or Se-K on the growth, water physiological parameters (gaseous exchange and leaf water content), photosynthetic and antioxidant capacities, and hormonal balance of G. max seedlings grown under 1.0 mM Cd stress were studied. The results showed that 30 μM Se-K up-regulates water physiological parameters, photosynthetic indices, antioxidant systems, enzymatic gene expression, total antioxidant activity (TAA), and hormonal balance. In addition, it down-regulates levels of reactive oxygen species (ROS; superoxide free radicals and hydrogen peroxide), oxidative damage (malondialdehyde content as an indicator of lipid peroxidation and electrolyte leakage), Cd translocation factor, and Cd content of Cd-stressed G. max seedlings. These positive findings were in favor of seedling growth and development under Cd stress. However, 50 μM Se-Met was more efficient than 30 μM Se-K in promoting the above-mentioned parameters of Cd-stressed G. max seedlings. From the current results, we conclude Se-Met could represent a promising strategy to contribute to the development and sustainability of crop production on soils contaminated with Cd at a concentration of up to 1.0 mM. However, further work is warranted to better understand the precise mechanisms of Se-Met action under Cd stress conditions.

Point-of-Care Diagnosis on Selenium Nutrition Based on Time-Resolved Fluorometric Glycoaffinity Chromatography.

Given the lack of timely evaluation of the well-received selenium fortification, a neat lateral-flow chromatographic solution was constructed here by using the recently identified urinary selenosugar (Sel) as a strongly indicative marker. As there are no ready-made receptors for this synthetic standard, phenylboronic acid (PBA) esterification and Dolichos biflorus agglutinin (DBA) affinity joined up to pinch and pin down the analyte into a sandwich-type glycol complex. Pilot lectin screening on homemade glycan microarrays verified such a new pairing between dual recognizers as PBA-Sel-DBA with a firm monosaccharide-binding constant. To quell the sample autofluorescence, europium nanoparticles with efficient long-life afterglow were employed as conjugating probes under 1 μs excitation. After systematic process optimizations, the prepared Sel-dipstick achieved swift and sensitive fluorometry over the physiological level of the target from 0.1 to 10 μM with a detection limit down to 0.06 μM. Further efforts were made to eliminate matrix effects from both temperature and pH via an approximate formula. Upon completion, the test strips managed to quantify the presence of Sel in not just imitated but real human urine, with comparable results to those in the references. As far as we know, this would be the first in-house prototype for user-friendly and facile diagnosis of Se nutrition with fair accuracy as well as selectivity. Future endeavors will be invested to model a more traceable Se-supplementary plan based on the rhythmic feedback of Sel excretion.

Effect of inorganic arsenic in paddy soil on the migration and transformation of selenium species in rice plants

Selenium (Se) in paddy rice is one of the significant sources of human Se nutrition. However, the effect of arsenic (As) pollution in soil on the translocation of Se species in rice plants is unclear. In this research, a pot experiment was designed to examine the effect of the addition of 50 mg As/kg soil as arsenite or arsenate on the migration of Se species from soil to indica Minghui 63 and Luyoumingzhan. The results showed that the antagonism between inorganic As and Se was closely related to the rice cultivar and Se oxidation state in soil. Relative to the standalone selenate treatment, arsenite significantly (p < 0.05) decreased the accumulation of selenocystine, selenomethionine and selenate in the roots, stems, sheaths, leaves, brans and kernels of both cultivars by 21.4%-100.0%, 40.0%-100.0%, 41.0%-100%, 5.4%-96.3%, 11.3%-100.0% and 26.2%-39.7% respectively, except for selenocystine in the kernels of indica Minghui 63 and selenomethionine in the leaves of indica Minghui 63 and the stems of indica Luyoumingzhan. Arsenate also decreased (p < 0.05) the accumulation of selenocystine, selenomethionine and selenate in the roots, stems, brans and kernels of both cultivars by 34.9%-100.0%, 30.2%-100.0%, 11.3%-100.0% and 5.6%-39.6% respectively, except for selenate in the stems of indica Minghui 63. However, relative to the standalone selenite treatment, arsenite and arsenate decreased (p < 0.05) the accumulation of selenocystine, selenomethionine and selenite only in the roots of indica Minghui 63 by 45.5%-100.0%. Our results suggested that arsenite and arsenate had better antagonism toward Se species in selenate-added soil than that in selenite-added soil; moreover, arsenite had a higher inhibiting effect on the accumulation of Se species than arsenate.

Age-Dependent Developmental Changes of Selenium Content and Selenoprotein Expression and Content in Longissimus Dorsi Muscle and Liver of Duroc Pigs.

The trace element selenium (Se) plays a key role in development and various physiological processes, mainly through its transformation into selenoproteins. To investigate the developmental patterns of Se content and expression of selenoproteins, the liver and longissimus dorsi (LD) muscle of Duroc pigs were collected at 1, 21, 80, and 185days of age (7 pigs each age) for the determination of Se content, mRNA expression of selenoproteins, and concentrations of glutathione peroxidase (GPX), thioredoxin reductase (TrxR or TXNRD), and selenoprotein P (SELP). The results showed that age significantly affected the expression of GPX1, GPX2, GPX3, TXNRD1, TXNRD2, TXNRD3, iodothyronine deiodinases 2 (DIO2), DIO3, SELF, SELH, SELM, SELP, SELS, SELW, and selenophosphate synthetase2 (SPS2) in the liver, as well as GPX3, GPX4, TXNRD1, TXNRD2, DIO2, DIO3, SELF, SELN, SELP, SELR, SELS, and SELW in the LD muscle of Duroc pigs. The concentrations of GPX, TrxR, and SELP showed an increasing trend with age, and they were positively correlated with Se content at 1, 21, and 185days of age and negatively correlated at 80days of age, both in the liver and LD muscle. The Se content decreased at the age of 80days, especially in the LD muscle. In summary, our study revealed developmental changes in Se content and expression of selenoproteins in the liver and LD muscle of Duroc pigs at different growth stages, which provided a theoretical basis for further study of Se nutrition and functions of selenoproteins.

Selenium Requirements of Rats for Normal Hepatic and Thyroidal 5′-Deiodinase (Type I) Activities

The nutritional requirement of selenium for type I 5'-deiodinase activity in thyroid compared with liver was assessed in rats. Male weanling Sprague-Dawley rats were fed a torula yeast-based diet for 20 wk. One group of rats was fed the Se-deficient basal diet (0.01 mg Se/kg). The other three groups were fed the basal diet plus sodium selenite at 0.05, 0.1 and 0.5 mg Se/kg diet. Liver 5'-deiodinase and glutathione peroxidase (GSH-Px) activities were depressed in the group fed the Se-deficient (basal) diet compared with the other groups. Liver 5'-deiodinase activity in the group fed 0.05 mg Se/kg diet was as high as in the groups fed 0.1 and 0.5 mg Se/kg diet, whereas GSH-Px activities in the groups fed 0.05 and 0.1 mg Se/kg diet were intermediate in value. Feeding the Se-deficient diet for 20 wk did not cause a suppression in 5'-deiodinase in the thyroid, and thyroid GSH-Px activity was approximately 40% of that in the other groups. In rats fed Se-supplemented diets, thyroid GSH-Px was approximately 20% or less of the activity found in liver. Plasma thyroxine was higher in the group fed the Se-deficient (basal) diet, but there were no differences in plasma 3,3',5-triiodothyronine among all groups. The results suggest that the nutritional Se requirement for 5'-deiodinase is less than that for GSH-Px and is approximately 0.05 mg Se/kg in the diet for normal activity in the liver and approximately 0.01 mg Se/kg for normal activity in the thyroid. Thyroid seems to be a priority organ over liver for Se when the intake of the element is limited.

Dietary Selenium Across Species.

This review traces the discoveries that led to the recognition of selenium (Se) as an essential nutrient and discusses Se-responsive diseases in animals and humans in the context of current understanding of the molecular mechanisms of their pathogeneses. The article includes a comprehensive analysis of dietary sources, nutritional utilization, metabolic functions, and dietary requirements of Se across various species. We also compare the function and regulation of selenogenomes and selenoproteomes among rodents, food animals, and humans. The review addresses the metabolic impacts of high dietary Se intakes in different species and recent revelations of Se metabolites, means of increasing Se status, and the recycling of Se in food systems and ecosystems. Finally, research needs are identified for supporting basic science and practical applications of dietary Se in food, nutrition, and health across species.

Effects of different forms and application methods of selenium fertilizers on wheat selenium uptake and utilization and its residual availability

<p id="C3">A two-year positioning field experiment was conducted to determine the reasonable regulation measures of selenium (Se) fertilizer for improving wheat grain Se nutrition, and to explore the feasibilities of different Se application approaches in Se agronomic biofortification of wheat grown in the typical Se-deficient soils of Yongshou County, Shaanxi Province. To study the effects of different forms and application methods of Se fertilizers on wheat yield, Se concentration and its accumulation and utilization, with the goal of producing wheat grain with Se concentration of 100 μg kg ^-1, five Se application rates of 0, 15, 18, 700, and 45 g hm^-2 were calculated for the treatments of no Se application (control), soil- and foliar-sodium selenate, and soil- and foliar-sodium selenite in the first year, respectively. In the following wheat season, for further investigating the residual Se availability, no Se fertilizer was applied and each plot was divided into straw removal and straw return. These results showed that the wheat grain yield and straw biomass were not influenced by Se forms and application methods. For the first wheat season, grain Se concentration reached the expected target value with a range of 109-397 μg kg ^-1, and the flour Se concentration varied from 101 μg kg ^-1 to 356 μg kg ^-1 for all the Se application treatments. In the next year, both grain and white flour Se concentrations were 100 μg kg ^-1 higher than under the treatment of soil-sodium selenite, and there was no significant difference of straw removal and straw return. Grain Se biofortification index was 4.7, 16, 0.3, 8.0 (μg kg^-1) (g hm^-2)^-1 for soil- and foliar-sodium selenate, and soil- and foliar-sodium selenite, respectively. The Se use efficiency was the highest for foliar-sodium selenate (7.3%), whereas its cumulative use efficiency was only 0.3% in soil-sodium selenite treatment with the long-term residue effects. At wheat harvest, the highest soil available Se was observed for soil-sodium selenite, with 91 μg kg ^-1 and 107 μg kg ^-1 for the straw removal and straw return, respectively. In conclusion, both soil- and foliar-sodium selenate /selenite were beneficial for producing wheat grain with target Se concentration of 100 μg kg ^-1, and the sodium selenite requirement was the highest, and its residual availability should be taken into consideration for Se biofortification in wheat production in the Se-deficient area of Chinese Loess Plateau.

Characteristics of Se in water-soil-plant system and threshold of soil Se in seleniferous areas in Enshi, China

Se-enrichment characteristics in water-soil-plant system and dietary Se status of local residents in seleniferous areas were investigated. Results showed that Se in well water might mainly derived from Se-enriched shales and coals, and Se mobility in seleniferous soils was relatively low with less than 6.7% bioavailable forms in high-Se areas. Soil Se with irrigation, precipitation and fertilization sources contributed more to soil Se than Se-enriched shales and coals in low-Se areas, resulting in slightly higher mobility of Se in low-Se soils. Se concentration in edible parts of main crops ranged from 0.005 mg kg−1 to 4.17 mg kg−1, and cereal plants had a higher Se-enrichment ability than tuber plants. The probable dietary Se intake (PDI) in high-Se areas was decreased to 959.3 μg d−1 in recent years, which might be attributed to tap water as drinking water in recent year rather than well water-dependent and changes in dietary structure, but still far above the permissible value of 400 μg d−1. Reducing cereal-derived dietary Se intake is an important strategy to better Se nutrition status in high-Se areas. After synthesis considerations on soil Se bioavailability and PDI of Se, the soil total Se of 4 mg kg−1 and the soil available Se content of 0.32 mg kg−1 were proposed to be the reference threshold values of soil Se excess in high-Se areas in Enshi, respectively.

Effect of dietary supplements on Se bioavailability: A comprehensive in vitro and in vivo study

Selenium (Se) is an essential micronutrient for animals and humans, and it is present in many different forms with different levels of bioaccessibility in food. Based on the maldistribution of Se and overall low level of Se dietary intake in China, an integrated study was conducted in this thesis to provide references for the regulation of Se nutrition. An in vitro simulation test was used to monitor the concentration effects, the impacts of dietary supplement combinations on the bioaccessibility of Se were examined in rice, and a model animal experiment (in vivo) was used to evaluate the practicability of the Se nutrition regulation scheme. The main results were as follows: the bioaccessibility of Se was effectively increased by 30 mg·d−1 VE (VE), 300 mg·d−1 VC + 300 μg·d−1 VB9 (VC+VB9) and 30 mg·d−1 VE + 300 mg·d−1 VC + 300 μg·d−1 VB9 (3IN1) (P < 0.05). The results of the healthy broiler tests showed that the 3 treatments increased the weight and Se content of the broilers, and 3IN1 had the most significant effect (P < 0.05). VC+VB9 was the best at promoting GPx activity, while 3IN1 was the best at promoting SOD activity and the inhibition of MDA content in broilers. The results suggested that VE, VC+VB9 and 3IN1 can benefit the bioavailability of Se and the antioxidant capacity of the body. The results can be used as a scientific reference for Se nutrition regulation.

Effect of an Established Nutritional Level of Selenium on Energy Metabolism and Gene Expression in the Liver of Rainbow Trout.

The nutritional selenium (Se) has been demonstrated to have health-boosting effects on fish. However, its effect on fish energy metabolism remains unclear. This study explores the effect and underlying mechanism of the action of nutritional Se on energy metabolism in fish. Rainbow trout (Oncorhynchus mykiss) were fed a basal diet (0mg Se/kg diet) and a diet containing an already established nutritional Se level (2mg Se/kg diet, based on Se-yeast) for 30days. After the feeding experiment, the plasma and liver biochemical profiles and liver transcriptome were analyzed. The results showed that the present nutritional level of Se significantly increased liver triglyceride, total cholesterol, and plasma total cholesterol contents (P < 0.05) compared with the control. Transcriptome analysis showed that 336 and 219 genes were significantly upregulated and downregulated, respectively. Gene enrichment analysis showed that many differentially expressed genes (DEGs) were associated with lipid metabolism pathways (fatty acid biosynthesis, fatty acid elongation, and unsaturated fatty acid biosynthesis), carbohydrate metabolism pathways (glycolysis, the pentose phosphate pathway, and the citrate cycle), and the oxidative phosphorylation pathway. Real-time quantitative PCR (Q-PCR) validation results showed that the expression profiles of 15 genes exhibited similar trends both in RNA sequencing (RNA-seq) and Q-PCR analysis. These results reveal that optimum dietary Se activates glucose catabolic processes, fatty acid biosynthetic processes, and energy production and hence produces higher liver lipid content. This study concludes that the previously established level of nutritional Se (Se-yeast) (2mg/kg diet, fed basis) for rainbow trout promotes energy storage in the liver, which may benefit fish growth to some extent.

Uses of Selenium Nanoparticles in the Plant Production

Plant production today depends on the ability of agriculturists to transport and recycle minerals, particularly those minerals which are nutritionally important to animals and human beings, through various agriculture products. It is important to note that the attenuation of these mineral deposits by green plants, as well as their subsequent role in the production of organic compounds, is fundamental to almost all known forms of life. Selenium (Se) is among those trace mineral which are crucial for the maintenance of plant physiology. The significance, production, and biological effects of this element, as well as its application in sustainable development, are remaining an interesting topic of discussion. Moreover, there has been a huge rise in the potential applications of nanotechnology in the food and agriculture industries. Several studies have been conducted on the various biological activities of selenium nanoparticles (SeNPs) and their biosynthesis. There is plenty of research performed on the effects of Se in plant nutrition and physiology, but there is a lack of information about the effects of SeNPs in SeNPs toxicity, and other aspects of using SeNPs in agriculture. The current review is focused on recent information related to the effects and fate of SeNPs in agronomy. We also aimed attention at the primary sources and behavior of Se in different environments, such as soil, water, air, and plants. All the data provides an extremely fertile domain for future investigation and research.

Selenium Biofortification: Roles, Mechanisms, Responses and Prospects.

The trace element selenium (Se) is a crucial element for many living organisms, including soil microorganisms, plants and animals, including humans. Generally, in Nature Se is taken up in the living cells of microorganisms, plants, animals and humans in several inorganic forms such as selenate, selenite, elemental Se and selenide. These forms are converted to organic forms by biological process, mostly as the two selenoamino acids selenocysteine (SeCys) and selenomethionine (SeMet). The biological systems of plants, animals and humans can fix these amino acids into Se-containing proteins by a modest replacement of methionine with SeMet. While the form SeCys is usually present in the active site of enzymes, which is essential for catalytic activity. Within human cells, organic forms of Se are significant for the accurate functioning of the immune and reproductive systems, the thyroid and the brain, and to enzyme activity within cells. Humans ingest Se through plant and animal foods rich in the element. The concentration of Se in foodstuffs depends on the presence of available forms of Se in soils and its uptake and accumulation by plants and herbivorous animals. Therefore, improving the availability of Se to plants is, therefore, a potential pathway to overcoming human Se deficiencies. Among these prospective pathways, the Se-biofortification of plants has already been established as a pioneering approach for producing Se-enriched agricultural products. To achieve this desirable aim of Se-biofortification, molecular breeding and genetic engineering in combination with novel agronomic and edaphic management approaches should be combined. This current review summarizes the roles, responses, prospects and mechanisms of Se in human nutrition. It also elaborates how biofortification is a plausible approach to resolving Se-deficiency in humans and other animals.

Tissue localization of selenium of parental or dietary origin in rainbow trout (Oncorhynchus mykiss) fry using LA-ICP MS bioimaging

Abstract In relation to the decrease of selenium (Se) content in aquafeeds, the impact of level and form of parental and dietary Se supplementation was investigated in rainbow trout fry using laser ablation-inductively coupled plasma mass spectrometry (LA-ICP MS) bioimaging. The offspring of rainbow trout broodstock, fed either a control diet without any Se supplementation (0.3 mg Se/kg diet) or a diet supplemented with Se (0.6 mg Se/kg diet) either as sodium selenite or hydroxy-selenomethionine, were sampled at swim-up fry stage or after 11 weeks of cross-feeding. Total body Se levels were influenced by parental Se nutrition in swim-up fry and by direct Se feeding in 11-week fry with higher levels in the Se-supplemented groups compared with the control and the highest levels in the hydroxy-selenomethionine treatment. The Se retention was lower for dietary sodium selenite. Selenomethionine levels increased when Se was provided as hydroxy-selenomethionine. LA-ICP MS maps revealed yolk in swim-up fry and intestine, liver, and kidney in 11-week fed fry as tissues with high Se abundance. In swim-up fry, muscle Se was the highest abundant when parents were fed hydroxy-selenomethionine. In 11-week fed fry, muscle Se abundance was higher in the head part of fry fed both Se-supplemented diets, but only in the tail part of fry fed hydroxy-selenomethionine. Liver Se abundance was higher in fry fed sodium selenite compared with the control diet supporting the hypothesis that tissue Se distribution can be influenced by parental and dietary Se forms and levels.

Exploring the new dimensions of selenium research to understand the underlying mechanism of its uptake, translocation, and accumulation.

Selenium (Se) is a vital mineral for both plants and animals. It is widely distributed on the earth's crust and is taken up by the plants as selenite or selenate. Plants substantially vary in their physiological response to Se. The amount of Se in edible plants is genetically controlled. Its availability can be determined by measuring its phytoavailability in soil. The low concentration of Se in plants can help them in combating stress, whereas higher concentrations can be detrimental to plant health and in most cases it is toxic. Thus, solving the double-edged sword problem of nutritional Se deficiency and its elevated concentrations in environment requires a better understanding of Se uptake and metabolism in plants. The studies on Se uptake and metabolism can help in genetic biofortification of Se in plants and also assist in phytoremediation. Moreover, Se uptake and transport, especially biochemical pathways of assimilation and incorporation into proteins, offers striking mechanisms of toxicity and tolerance. These developments have led to a revival of Se research in higher plants with significant break throughs being made in the previous years. This review explores the new dimensions of Se research with major emphasis on key research events related to Se undertaken in last few years. Further, we also discussed future possibilities in Se research for crop improvement.

Sex-dependent association between selenium status and cognitive performance in older adults.

Selenium (Se) is an essential nutrient required for maintaining brain health across lifespan, and adequate nutritional Se status has been positively associated with sustained cognitive performance in older adults. However, critical physiological sex differences in Se metabolism have not been specifically assessed in human studies. Therefore, we aimed to investigate sex differences in the association between Se concentration in whole blood and cognitive performance in US older adults. This cross-sectional study included 2016 participants (984 male and 1032 female) ≥ 60 years from the 2011 to 2014 National Health and Nutrition Survey (NHANES). All participants were assessed for whole blood Se concentration and completed the following battery of cognitive tests: Consortium to Establish a Registry for Alzheimer's Disease (CERAD) Word Learning Test, Animal Fluency test, and Digit Symbol Substitution Test (DSST). In this cohort, all participants presented with adequate Se status (mean 196.7μg/L; 95% CI 193.5, 200.0), and cohort-wide scores were equivalent to a cognitively healthy population. A sex effect on CERAD recall (P = 0.005) and animal fluency (P = 0.018) was observed in models adjusted for age, diabetes, history of cardiovascular disease, physical activity and body mass index. Se concentration was positively associated with CERAD recall (β: 0.015, 95% CI 0.007, 0.022) and animal fluency (β: 0.017, 95% CI 0.003, 0.030) performance in males only, while no associations were observed for females. This study provides the first evidence for sex differences in the association between Se status and cognitive performance in older adults.

Dietary Serine and Sulfate-Containing Amino Acids Related to the Nutritional Status of Selenium in Lactating Chinese Women.

Previous studies suggested that serine can promote the synthesis of selenoproteins and the interaction, transformation, and replacement of serine, cysteine, and selenocysteine have been observed in the human body. This study was designed to clarify whether the dietary intakes of serine and sulfate-containing amino acids (SAAs) could directly affect the selenium (Se) nutritional status or the level of milk Se in lactating women. Breast milk and plasma samples were collected from a total of 264 lactating Chinese women when they revisited their local hospital at the 42nd day postpartum to detect the concentration of Se with ICP-MS and the content of selenoprotein P (SEPP1) and the activity of glutathione peroxidase 3 (GPX3) in the plasma by ELISA. The daily Se intake by each subject was calculated based on her own plasma Se concentration. The 24-h dietary record data for 3 consecutive days were collected to calculate their dietary intakes of protein together with each amino acid daily based on the China Food Composition Tables (CFCT). Ordinal polytomous logistic regression was applied to examine the determinants of BMI values for lactating women. For all subjects, the concentration of plasma SEPP1 and milk Se of participants with insufficient Se intake were significantly associated with the dietary intake of serine and 2 SAAs (methionine and cystine), respectively (P < 0.05). No significant correlation was found between each amino acid related to the synthesis of endogenous serine and every biomarker of the Se nutrition status in subjects with an insufficient dietary protein intake (P > 0.05). The ordinal logistic regression analysis showed that dietary protein intake (ordinal OR 1.012, 95% CI = 0.004-0.020, P = 0.002) and plasma SEPP1 (ordinal OR 0.988, 95% CI = - 0.023 to - 0.001, P = 0.036) affected the BMI value together in these lactating women. In conclusion, dietary serine and SAAs were found to directly affect the nutritional status, and both high protein intake and low plasma SEPP1 might be the health risks in these lactating Chinese women.

Selenium Deficiency Is Widespread and Spatially Dependent in Ethiopia

Selenium (Se) is an essential element for human health and livestock productivity. Globally, human Se status is highly variable, mainly due to the influence of soil types on the Se content of crops, suggesting the need to identify areas of deficiency to design targeted interventions. In sub-Saharan Africa, including Ethiopia, data on population Se status are largely unavailable, although previous studies indicated the potential for widespread Se deficiency. Serum Se concentration of a nationally representative sample of the Ethiopian population was determined, and these observed values were combined with a spatial statistical model to predict and map the Se status of populations across the country. The study used archived serum samples (n = 3269) from the 2015 Ethiopian National Micronutrient Survey (ENMS). The ENMS was a cross-sectional survey of young and school-age children, women and men. Serum Se concentration was measured using inductively coupled plasma mass spectrometry (ICPMS). The national median (Q1, Q3) serum Se concentration was 87.7 (56.7, 123.0) μg L−1. Serum Se concentration differed between regions, ranging from a median (Q1, Q3) of 54.6 (43.1, 66.3) µg L−1 in the Benishangul-Gumuz Region to 122.0 (105, 141) µg L−1 in the Southern Nations, Nationalities, and Peoples’ Region and the Afar Region. Overall, 35.5% of the population were Se deficient, defined as serum Se < 70 µg L−1. A geostatistical analysis showed that there was marked spatial dependence in Se status, with serum concentrations greatest among those living in North-East and Eastern Ethiopia and along the Rift Valley, while serum Se concentrations were lower among those living in North-West and Western Ethiopia. Selenium deficiency in Ethiopia is widespread, but the risk of Se deficiency is highly spatially dependent. Policies to enhance Se nutrition should target populations in North-West and Western Ethiopia.

Oxidative stress and antioxidant response in rainbow trout fry exposed to acute hypoxia is affected by selenium nutrition of parents and during first exogenous feeding

Selenium (Se) deficiency is a problem widely encountered in humans and terrestrial livestock production with increasing attention also in aquaculture. Se supports the antioxidant system, which becomes especially important during stressful conditions. In the present study, the effect of Se-supplementation in broodstock and fry diets on the performance and antioxidant metabolism of rainbow trout fry under acute hypoxia was investigated. Rainbow trout broodstock were fed plant-ingredient based diets either without any Se-supplementation (Se level: 0.3 mg/kg) or supplemented with Se supplied as sodium selenite or as hydroxy-selenomethionine (Se level: 0.6 mg/kg respectively) for 6 months prior to spawning. The progenies were subdivided into three triplicate feeding groups and fed diets with similar Se levels compared to the parental diets, resulting in a 3x3 factorial design. After 11 weeks of feeding, the fry were either sampled or subjected to a hypoxic stress challenge. One hundred fish were transferred to tanks containing water with a low oxygen level (1.7 ± 0.2 ppm) and monitored closely for 30 min. When a fish started to faint it was recorded and transferred back to normoxic water. Direct fry feeding of the hydroxy-selenomethionine supplemented diet improved the resistance towards the hypoxic stress. On the contrary, fry originating from parents fed Se-supplemented diets showed a lower stress resistance compared to fry originating from parents fed the control diet. Fry subjected to hypoxia showed elevated oxidative stress with reduced glutathione (GSH) levels and increased isoprostanes (IsoP) and phytoprostanes (PhytoP) levels produced by lipid peroxidation of polyunsaturated fatty acids (PUFA), arachidonic and α-linolenic acids respectively. Increased mRNA expression of transcription factors (nrf2, nfκb, keap1X2) and decreased mRNA expression of antioxidant enzymes (trxr, sod, gstπ) indicated a transcriptional regulation of the antioxidant response. In stressed fry, the mRNA expression of several antioxidant genes including gr, msr and gstπ was found to be higher when fed the control diet compared to the sodium selenite treatment, with a contrary effect for parental and direct Se nutrition on gpx. The long-term parental effect becomes of greater importance in stressed fry, where more than half of the genes were significantly higher expressed in the control compared to the selenite supplemented group.

Selenium mitigates cadmium toxicity by preventing oxidative stress and enhancing photosynthesis and micronutrient availability on radish (Raphanus sativus L.) cv. Cherry Belle.

We aimed to examine the effects of selenium on the tolerance of radish plants CV. Cherri Belle under cadmium phytotoxicity. The biomass accumulation was drastically decreased under Cd toxicity and the supplementary Se maintained the biomass acquisition under Cd pressure. The chlorophyll index (SPAD), PSII efficiency (Fv/Fm), and PSII quantum yield (ΦPSII) were declined in response to Cd treatment, while Se nutrition improved these variables in a dose-dependent manner. The highest H2O2 and MDA contents were observed in the plants fed with 10mg-1L Cd. The Cd stress resulted in a considerable decline in the activities of GPX, CAT, and APX antioxidant enzymes, while Se supplementation increased their activities in the Cd-treated plants. Based on the mineral analyses, no Cd was traced in the control plants, while the Cd concentration in both roots and leaves of the Cd-stressed radish plants increased with increasing the supplemented Cd levels. Compared with plants solely treated with 10mgL-1 Cd, Se nutrition declined the Cd absorption in roots and in leaves. The concentration of evaluated micronutrients including Fe, Mn, Cu, and Zn tended to decrease in the Cd-imposed plants in comparison with control plants. Se nutrition of both stressed and non-stressed radish plants increased the concentrations of the studied microelements, except for Zn in which the individual use of Se led to a decrease in the Zn content. Significant positive and negative correlation values were found among the studied traits and the principle component analysis (PCA) biplot and Ward dendrogram confirmed the results of the correlation analysis. Se proved to be efficient in the alleviation of Cd-triggered deleterious effects by improving biomass acquisition, enhancing chlorophyll biosynthesis and fluorescence, and increasing micronutrient uptake in a dose-dependent manner. Furthermore, the Se alleviation mechanism under Cd stress was also connected with the activation of enzymatic antioxidative protection system as well as with decreasing Cd uptake, transport, and distribution in radish leaves. Altogether, our research strongly suggests the implementation of Se in the growth medium to enhance the tolerance of radish plants under Cd stress.

The Correlation between Dietary Selenium Intake and Type 2 Diabetes: A Cross-Sectional Population-Based Study on North Chinese Adults.

The relationship between selenium (Se) and type 2 diabetes (T2D) remains controversial. In previous animal and cell studies, Se was found to be insulin mimic and antidiabetic, whereas recent epidemiological and interventional trials have shown an unexpected association between high Se intake and increased risk of T2D. The present study aimed to investigate the significance of dietary Se and T2D in North Chinese adults. A large sample of the population was enrolled through cluster sampling in Northern China (N=8824). Information on basic characteristics, anthropometric measures, and dietary Se intake was collected from each subject for analysis. Multivariable logistic regression was used to investigate the association between dietary Se and T2D through adjusted odds ratio (OR) and the corresponding 95% confidence interval (CI). The average nutritional Se intake was 52.43 μg/day, and the prevalence of T2D was 20.4% in the studied population. The OR for developing T2D was 1.66 (95% CI: 1.38, 1.99; P for linear trend <0.005), comparing the highest to the lowest quintile of energy-adjusted Se intake in multivariate logistic regression analysis. The mediation analysis discovered that glucose metabolism (indicated by FBG and HbA1c) mediated this association. In conclusion, our research adds further support to the role of high dietary Se in the incidence of T2D. The results also suggested that this association was mediated by glucose metabolism.