Effects of selenium-cadmium co-enriched Cardamine hupingshanensis on bone damage in mice.

Selenium (Se) and cadmium (Cd) usually co-existed in soils, especially in areas with Se-rich soils in China. The potential health consequences for the local populations consuming foods rich in Se and Cd are unknown. Cardamine hupingshanensis (HUP) is Se and Cd hyperaccumulator plant that could be an ideal natural product to assess the protective effects of endogenous Se against endogenous Cd-caused bone damage. Male C57BL/6 mice were fed 5.22 mg/kg cadmium chloride (CdCl2) (Cd 3.2 mg/kg body weight (BW)), or HUP solutions containing Cd 3.2 mg/kg BW and Se 0.15, 0.29 or 0.50 mg/kg BW (corresponding to the HUP0, HUP1 and HUP2 groups) interventions. Se-enriched HUP1 and HUP2 significantly decreased Cd-induced femur microstructure damage and regulated serum bone osteoclastic marker levels and osteogenesis-related genes. In addition, endogenous Se significantly decreased kidney fibroblast growth factor 23 (FGF23) protein expression and serum parathyroid hormone (PTH) levels, and raised serum calcitriol (1,25(OH)2D3). Furthermore, Se also regulated gut microbiota involved in skeletal metabolism disorder. In conclusion, endogenous Se, especially with higher doses (the HUP2 group), positively affects bone formation and resorption by mitigating the damaging effects of endogenous Cd via the modulation of renal FGF23 expression, circulating 1,25(OH)2D3 and PTH and gut microbiota composition.

Life-cycle selenium accumulation and its correlations with the rhizobacteria and endophytes in the hyperaccumulating plant Cardamine hupingshanensis.

Cardamine hupingshanensis (C. hupingshanensis) is known for its ability to hyperaccumulate selenium (Se). However, the roles of the rhizobacteria or endophytes in Se hyperaccumulation have not been explored in C. hupingshanensis. Here, in-situ-like pot experiments were conducted to investigate the characteristics of Se accumulation throughout C. hupingshanensis growth stages and its correlations with rhizobacteria and endophytes under varying soil Se levels. Results showed that Se levels in roots, stems and leaves increased from the seedling to bolting stage, but remained relatively stable during the flowering and maturity. Leaves exhibited the highest Se levels (736.48 ± 6.51 mg/kg DW), followed by stems (575.39 ± 27.05 mg/kg DW), and lowest in roots (306.62 ± 65.45 mg/kg DW) under high-Se stress. The Se translocation factors from soils to C. hupingshanensis roots was significantly higher (p < 0.05) in low-Se soils compared to medium- and high-Se soils. Rhizobacterial diversity showed significant positive correlations (p < 0.05) with both total and bioavailable soil Se contents. The levels of soil Se and growth stages of C. hupingshanensis were found to have significant effects (p < 0.03) on the compositions of rhizosphere bacteria and C. hupingshanensis endophytes. Low-abundance bacteria (< 5%), including Gemmatimonadetes, Latescibacteria and Nitrospirae, were identified to potentially increase the bioavailable Se levels in the rhizosphere. The Se accumulation significantly decreased (p < 0.05) in C. hupingshanensis grown in sterilized low- (32.4%), medium- (17%) and high-Se (42%) soils. Endophytes in C. hupingshanensis, such as Firmicutes and Proteobacteria, were likely recruited from the rhizobacteria, as evidenced by the isolated bacterial strains, and played an important role in Se hyperaccumulation, particularly during the flowering stage. This study provides new insights into potential mechanism underlying Se hyperaccumulation in C. hupingshanensis.

Effects of selenite on the responses of lettuce (Lactuca sativa L.) to polystyrene nano-plastic stress.

Nowadays, nano-plastics are widespread in agricultural soils and could be uptaken by crops to cause an increased risk for food safety. As a beneficial element for plants, selenium (Se) can alleviate oxidative damages under various environmental stresses (eg. heavy metals, heat, cold). This study investigated the single and co-applications of nano-size polystyrene (PS) (80 nm and 200 nm) and selenite (0.8 ppm and 5 ppm) in lettuce (Lactuca sativa L.). Results showed nano-PS significantly decreased the root-shoot fresh biomass ratios, inhibited physiological functions in roots and leaves (e.g. root length, chlorophyll content and net photosynthetic rate), as well as stimulated the activities of the antioxidant enzymes in roots and shoots with greater toxicity at the smaller particle size (80 nm). However, both exogenous selenite applications significantly alleviated the above toxic effects of nano-PS in lettuces, especially at a high Se level of 5 ppm. Regression Path Analysis (RPA) revealed that regulation of chlorophyll levels by Se might be a key mechanism for counteracting PS stress in lettuces, which led to the increase in indigenous defense capacity. The present findings provide a novel but safer and cleaner agricultural strategy to alleviate or minimize nano-plastics toxicity in agricultural soils for staple crops and vegetables via application of Se.

A novel selenite-tolerant rhizosphere bacterium Wautersiella enshiensis sp. nov., isolated from Chinese selenium hyperaccumulator, Cardamine hupingshanensis.

Selenium (Se) is a dietary essential trace element for humans with various physiological functions and it could also be accumulated by some plant species, like Astragalus bisulcatus, Stanleya pinnata, and Cardamine hupinshanensis. A novel Gram-stain-negative, facultatively anaerobic, selenite-tolerant bacterium, designated strain YLX-1T , was isolated from the rhizosphere of a Se hyperaccumulating plant, Cardamine hupingshanensis in Enshi, China. Phylogenetic analysis based on 16 S rRNA gene sequences indicated that strain YLX-1T is a potential new species in the genus Wautersiella. Strain YLX-1T could grow in the temperature range of 4-37°C (optimally at 28°C) and in the pH range of 5-9 (optimum pH 7), which also could tolerate Se up to 6000 mg Se/L via producing extracellular red nano-Se with 100-300 nm size. However, it could predominantly accumulate selenocystine (SeCys2 ) in the cell under lower Se stress (1.5 mg Se/L). These results would help broaden our knowledge about the Se accumulation and transformation mechanism involved in rhizosphere bacteria like strain YLX-1T in C. hupingshanensis. Based on polyphasic data, we propose the creation of the new species Wautersiella enshiensis sp. nov., strain YLX-1T ( = CCTCC M 2013671) which will be promising to produce nano-Se as fertilizer, food additives or medicine.

Geographical pattern of minerals and its association with health disparities in the USA.

This study aimed to determine the common latent patterns of geographical distribution of health-related minerals across the USA and to evaluate the real-world cumulative effects of these patterns on overall population health. It was an ecological study using county-level data (3080 contiguous counties) on the concentrations of 14 minerals (i.e., aluminum, arsenic, calcium, copper, iron, lead, magnesium, manganese, mercury, phosphorus, selenium, sodium, titanium, zinc) in stream sediments (or surface soils), and the measurements of overall health including life expectancy at birth, age-specific mortality risks and cause-specific (summarized by 21 mutually exclusive groups) mortality rates. Latent class analysis (LCA) was employed to identify the common clusters of life expectancy-related minerals based on their concentration characteristics. Multivariate linear regression analyses were then conducted to examine the relationship between the LCA-derived clusters and the health measurements, with adjustment for potential confounding factors. Five minerals (i.e., arsenic, calcium, selenium, sodium and zinc) were associated with life expectancy and were analyzed in LCA. Three clusters were determined across the USA, the 'common' (n = 2056, 66.8%), 'infertile' (n = 739, 24.0%) and 'plentiful' (n = 285, 9.3%) clusters. Residents in counties with the 'infertile' profile were associated with the shortest life expectancy, highest mortality risks at all ages, and highest mortality rates for many reasons including the top five leading causes of death: cardiovascular diseases, neoplasms, neurological disorders, chronic respiratory conditions, and diabetes, urogenital, blood and endocrine diseases. Results remained statistically significant after confounding adjustment. Our study brings novel perspectives regarding environmental geochemistry to explain health disparities in the USA.

Geographical distribution of trace elements (selenium, zinc, iron, copper) and case fatality rate of COVID-19: a national analysis across conterminous USA.

Severe outcome particularly death is the largest burden of COVID-19. Clinical observations showed preliminary data that deficiency in certain trace elements, essential for the normal activity of immune system, may be associated with worse COVID-19 outcome. Relevant study of environmental epidemiology has yet to be explored. We investigated the geographical association between concentrations of Se, Zn, Fe and Cu in surface soils and case fatality rate of COVID-19 in USA. Two sets of database, including epidemiological data of COVID-19 (including case fatality rate, from the University of John Hopkinson) and geochemical concentration data of Se, Zn, Fe and Cu in surface soils (from the National Geochemical Survey), were mapped according to geographical location at the county level across conterminous USA. Characteristics of population, socio-demographics and residential environment by county were also collected. Seven cross-sectional sampling dates, with a 4-week interval between adjacent dates, constructed an observational investigation over 24 weeks from October 8, 2020, to March 25, 2021. Multivariable fractional (logit) outcome regression analyses were used to assess the association with adjustment for potential confounding factors. In USA counties with the lowest concentration of Zn, the case fatality rate of COVID-19 was the highest, after adjustment for other influencing factors. Associations of Se, Fe and Cu with case fatality rate of COVID-19 were either inconsistent over time or disappeared after adjustment for Zn. Our large study provides epidemiological evidence suggesting an association of Zn with COVID-19 severity, suggesting Zn deficiency should be avoided.

Effects of sulfur application on selenium uptake and seed selenium speciation in soybean (Glycine max L.) grown in different soil types.

AIMS: The objective of the present study was to elucidate the effects of sulfur (S) application on selenium (Se) uptake and seed Se speciation in high-protein soybean (Glycine max L.) grown in different soil types. METHODS: Pot experiments were conducted with soybean plants grown in yellow-brown soil (pH 5.68) and in calcareous alluvial soil (pH 7.87). Sodium selenate (Na2SeO4, 2 mg kg-1) was applied to soil with or without S fertilizer (S, 100 mg kg-1). RESULTS: Soybean grain yield and total biomass in calcareous alluvial soil were both approximately 1.3-fold the levels in yellow-brown soil. Following Se application, seed Se concentration in calcareous alluvial soil was 3.2-fold the concentration in yellow-brown soil, although additional S application reduced the corresponding seed Se concentrations by 55.6% and 38.6%, respectively. Generally, Se application facilitated Se translocation and enrichment in soybean seeds. Organic Se accounted for 92% of seed total Se and Se-methionine (>90%) was always the major Se species. Available Se (soluble and exchangeable fractions) accounted for 50.7% (yellow-brown soil) and 70.1% (calcareous alluvial soil) of soil total Se under Se treatment, while additional S application decreased the corresponding proportion of soluble Se by 12.6% and 14.4%. CONCLUSIONS: The bioavailability of selenate in calcareous alluvial soil was higher than the bioavailability in yellow-brown soil and was more negatively affected by S application. Although S application inhibited Se uptake in soybean plants in both soil types, it did not influence seed Se speciation and Se-methionine was the major Se species.

Soil Selenium Concentration and Residents Daily Dietary Intake in a Selenosis Area: A Preliminary Study in Yutangba Village, Enshi City, China.

In 1963, selenosis occurred in Yutangba Village, Enshi City, China. Subsequently, local residents migrated to a new area of Yutangba to avoid high selenium (Se) exposure. In this study, 19 soil samples, 43 food samples, 60 hair samples and 58 plasma samples from local residents were randomly collected in New Yutangba Village. The mean total Se concentrations in cultivated soil samples were 1753.6 ± 742.8 µg/kg (n = 14). The estimated daily Se intake in New Yutangba Village decreased to 63.2 ± 39.8 µg/day, slightly higher than the recommended dietary Se intake for adults in China (60 µg/day). The mean Se concentrations in hair and plasma samples were 549.7 ± 165.2 µg/kg (n = 60) and 98.4 ± 32.1 µg/L (n = 58), respectively. The result indicated that appropriate activities, such as relocation, consuming a mixture of local foods and market foods containing low Se concentration, could effectively reduce the risk of high Se exposure.

Assessment of organochlorine pesticide contamination in waterbirds from an agricultural region, Central China.

Twenty-one organochlorine pesticides (OCPs) were measured in the muscle of six predominant waterbird species from Jianghan Plain, Hubei Province, Central China. Among OCPs, DDTs were the most prevalent compounds, with average concentration ranging from 31.1 to 1445 ng/g lipid weight. Little egrets (Egretta garzetta) and Chinese pond herons (Ardeola bacchus) showed significantly higher concentrations of OCPs (p < 0.05) due to their dietary habits and migratory patterns. There were no statistically significant differences (p > 0.05) for most OCPs between sex and age groups. The accumulation profiles of HCHs and DDTs suggested that these OCPs in Jianghan Plain were largely derived from historical usage. Risk assessment indicated that heptachlor could be likely to pose adverse health effects on people consuming ducks in Jianghan Plain.

Mercury Concentrations and Se:Hg Molar Ratios in Flyingfish (Exocoetus volitans) and Squid (Uroteuthis chinensis).

We measured total mercury (Hg) and selenium (Se) concentrations as well as stable nitrogen (N) isotopic composition in flyingfish and squid muscle tissues from the eastern Indian Ocean and western South China Sea. The results showed that the mean Hg concentration in squid muscle from the western South China Sea was lower than that in the eastern Indian Ocean. The Hg concentrations in flyingfish and squid muscle samples were positively correlated with organism size (length and weight) and δ15N in all the study areas. Furthermore, we found a negative correlation between Se and Hg in molar content of flyingfish and squid muscle from the western South China Sea. The Se:Hg molar ratio was significantly negative correlated with fish weight and δ15N, suggesting that the Se:Hg molar ratio decreases with the increase of fish size and trophic level in the food web.

Dietary nano-selenium relieves hypoxia stress and, improves immunity and disease resistance in the Chinese mitten crab (Eriocheir sinensis).

Hypoxia is a relevant physiological challenge for crab culture, and the hemolymph plays a crucial role in response to the hypoxia. In a 60 d feeding trial, Chinese mitten crabs (Eriocheir sinensis) fed a diet containing 0.2 mg/kg nano-selenium (nanoSe) showed a significantly increased weight gain rate (WGR) and a reduced feed coefficient (FC) compared to those fed diets with 0, 0.1, 0.4, 0.8, and 1.6 mg/kg nanoSe. Another 90 d feeding trial was conducted to determine the influence of dietary nanoSe on the immune response in juvenile Chinese mitten crabs kept under the condition of hypoxia. The results showed that hypoxia stress resulted in significantly increased hemocyte counts (THC, LGC, SGC, and HC), expression levels of the hemocyanin gene and protein, lactic acid level, and antioxidant capacity (T-AOC activities, SOD activities, GSH-Px and GSH content) in hemolymph supernatant. When these crabs were infected with Aeromonas hydrophila bacteria, hypoxia exposure increased mortality, but it was alleviated by a diet supplemented with 0.2 mg/kg nanoSe. The up-regulative effects of nanoSe (0.2 mg/kg) on antioxidant capacity, hemocyte counts, and hemocyanin expression under hypoxia exposure were further strengthened throughout, whereas lactic acid levels induced by hypoxia stress were restored. Thus, the observations in this study indicate that the level of dietary nanoSe is important in regulating immunity and disease resistance in crabs kept under hypoxia stress.

Inhibitory effect of selenium against Penicillium expansum and its possible mechanisms of action.

Some organic and inorganic salts could inhibit the growth of many pathogens. Selenium (Se), as an essential micronutrient, was effective in improving the plant resistance and antioxidant capacity at a low concentration. Penicillium expansum is one of the most important postharvest fungal pathogens, which can cause blue mold rot in various fruits and vegetables. In this study, the inhibitory effect of Se against P. expansum was evaluated. The result showed that Se strongly inhibited spore germination, germ tube elongation, and mycelial spread of P. expansum in the culture medium. The inhibitory effect was positively related to the concentration of Se used. Fluorescence microscopy observation of P. expansum conidia stained with propidium iodide (PI) indicated that the membrane integrity decreased to 37 % after the conidia were treated with Se (20 mg/l) for 9 h. With the use of an oxidant-sensitive probe 2,7-dichlorofluorescin (DCHF-DA), we found that Se at 15 mg/l could induce the generation of intracellular reactive oxygen species (ROS). Furthermore, methane dicarboxylic aldehyde (MDA) content, hydrogen peroxide (H2O2), and superoxide anion (O2 (-)) production rate in P. expansum spores exposed to Se increased markedly. Compared with the control, the activities of superoxide dismutase (SOD) and the content of glutathione (GSH) were reduced, confirming that damage of Se to cellular oxygen-eliminating system is the main reason. These results suggest that Se might serve as a potential alternative to synthetic fungicides for the control of the postharvest disease of fruit and vegetables caused by P. expansum.

Characterization of a selenium-tolerant rhizosphere strain from a novel Se-hyperaccumulating plant Cardamine hupingshanesis.

A novel selenium- (Se-) hyperaccumulating plant, Cardamine hupingshanesis, accumulating Se as a form of SeCys2, was discovered in Enshi, Hubei, China, which could not be explained by present selenocysteine methyltransferase (SMT) theory. However, it is interesting to investigate if rhizosphere bacteria play some roles during SeCys2 accumulation. Here, one Se-tolerant rhizosphere strain, Microbacterium oxydans, was isolated from C. hupingshanesis. Phylogenetic analysis and 16S rRNA gene sequences determined the strain as a kind of Gram positive bacillus and belonged to the family Brevibacterium frigoritolerans. Furthermore, Se tolerance test indicated the strain could grow in extreme high Se level of 15.0 mg Se L(-1). When exposed to 1.5 mg Se L(-1), SeCys2 was the predominant Se species in the bacteria, consistent with the Se species in C. hupingshanesis. This coincidence might reveal that this strain played some positive effect in SeCys2 accumulation of C. hupingshanesis. Moreover, when exposed to 1.5 mg Se L(-1) or 15.0 mg Se L(-1), As absorption diminished in the logarithmic phase. In contrast, As absorption increased when exposed to 7.5 mg Se L(-1), indicating As metabolism processes could be affected by Se on this strain. The present study provided a sight on the role of rhizosphere bacteria during Se accumulation for Se-hyperaccumulating plant.

Characterization of Selenium Speciation in Se-Enriched Crops: Crop Selection Approach.

Accurately quantifying selenium (Se) speciation and transformation in Se-enriched crops is highly significant for human health. The investigation of Se species in Se-enriched crops involves assessing the enrichment of both organic and inorganic Se species, considering their plant families and edible parts. The staple crops of rice, corn, and wheat showed no or less inorganic Se with the increase of total Se; however, potatoes expressed a proportion of selenate [Se(VI)]. In addition, the organic Se proportions in Se-enriched crops of Cruciferous, Brassicaceae, and Umbelliferae plant families were relatively lower than the proportion of inorganic Se. Concurrently, the edible parts of the Se-enriched gramineous or cereal crops enriched with organic Se and crops with fruit, stem, leaf, and root as edible parts contain the maximum percentage of organic Se with a certain proportion of inorganic Se. This study contributes to a sparse body of literature by meticulously discerning appropriate Se-enriched crop selection through a comprehensive evaluation of Se speciation and its organic and inorganic accumulation potential.

Protective effects and mechanism of chemical- and plant-based selenocystine against cadmium-induced liver damage.

Although selenium (Se) and cadmium (Cd) often coexist naturally in the soil of China, the health risks to local residents consuming Se-Cd co-enriched foods are unknown. In the present study, we investigated the effects of chemical-based selenocystine (SeCys2) on cadmium chloride-induced human hepatocarcinoma (HepG2) cell injury and plant (Cardamine hupingshanensis)-derived SeCys2 against Cd-induced liver injury in mice. We found that chemical- and plant-based SeCys2 showed protective effects against Cd-induced HepG2 cell injury and liver damage in mice, respectively. Compared with Cd intervention group, co-treatment with chemical- or plant-based SeCys2 both alleviated liver toxicity and ferroptosis by decreasing ferrous iron, acyl-CoA synthetase long-chain (ACSL) family member 4, lysophosphatidylcholine acyltransferase 3, reactive oxygen species and lipid peroxide levels, and increasing ACSL3, peroxisome proliferator-activated receptor α, solute carrier family 7 member 11 (SLC7A11) and glutathione and glutathione peroxidase 4 (GPX4) levels. In conclusion, chemical- and plant-based SeCys2 alleviated Cd-induced hepatotoxicity and ferroptosis by regulating SLC7A11/GPX4 signaling and lipid peroxidation. Our findings indicate that potential Cd toxicity from consuming foods grown in Se- and Cd-rich soils should be re-evaluated. This study offers a new perspective for the development of SeCys2-enriched agricultural products.

The use of selenium for controlling plant fungal diseases and insect pests.

The selenium (Se) applications in biomedicine, agriculture, and environmental health have become great research interest in recent decades. As an essential nutrient for humans and animals, beneficial effects of Se on human health have been well documented. Although Se is not an essential element for plants, it does play important roles in improving plants' resistances to a broad of biotic and abiotic stresses. This review is focused on recent findings from studies on effects and mechanisms of Se on plant fungal diseases and insect pests. Se affects the plant resistance to fungal diseases by preventing the invasion of fungal pathogen through positively affecting plant defense to pathogens; and through negative effects on pathogen by destroying the cell membrane and cellular extensions of pathogen inside plant tissues after invasion; and changing the soil microbial community to safeguard plant cells against invading fungi. Plants, grown under Se enriched soils or treated with Se through foliar and soil applications, can metabolize Se into dimethyl selenide or dimethyl diselenide, which acts as an insect repellent compound to deter foraging and landing pests, thus providing plant mediated resistance to insect pests; moreover, Se can also lead to poisoning to some pests if toxic amounts of Se are fed, resulting in steady pest mortality, lower reproduction rate, negative effects on growth and development, thus shortening the life span of many insect pests. In present manuscript, reports are reviewed on Se-mediated plant resistance to fungal pathogens and insect pests. The future perspective of Se is also discussed on preventing the disease and pest control to protect plants from economic injuries and damages.

Protective effects of epigallocatechin-3-o-gallate combined with organic selenium against transforming growth factor-beta 1-induced fibrosis in LX-2 cells.

In this study, we investigated the protective effects and possible mechanism of epigallocatechin-3-o-gallate (EGCG) combined with organic selenium in transforming growth factor (TGF)-ß1-activated LX-2 cells. After 12 h of starvation, LX-2 cells were treated with 10 ng/ml of recombinant TGF-ß1 and different concentrations of EGCG, L-selenomethionine (L-SeMet), or L-selenomethylcysteine (L-SeMC) for 24 h. We found that 100 and 200 µM EGCG combined with 1 mM L-SeMet or L-SeMC showed a synergistic effect in decreasing the survival rate of activated LX-2 cells. In addition, the combination of 100 mM EGCG and 1 mM L-SeMet or L-SeMC promoted the apoptosis of activated LX-2 cells. Compared with the EGCG treatment group, the combination intervention group had significantly suppressed levels of hepatic stellate cell activation markers including alpha-smooth muscle actin, collagen type I alpha 1, collagen type III alpha 1, 5-hydroxytryptophan (5-HT), and 5-HT receptors 2A and 2B. Moreover, interleukin-10 levels were decreased, while TGF-ß1 levels were increased after TGF-ß1 activation in LX-2 culture medium, whereas the combin1ation intervention reversed this phenomenon. The combination treatment had a more pronounced effect than any single treatment at the same dose. These results demonstrated that the combination of EGCG and organic selenium synergistically improves the TGF-ß1-induced fibrosis of LX-2 cells to some extent by promoting apoptosis and inhibiting cell activation. PRACTICAL APPLICATIONS: Here, we found that the effects of epigallocatechin-3-o-gallate (EGCG) + L-selenomethionine or L-selenomethylcysteine were more pronounced than those of EGCG alone. Future studies should investigate the protective effects of green tea and selenium-enriched green tea against hepatic fibrosis and explore the differences in their molecular mechanisms. The results of this study will be helpful for the development and utilization of selenium-enriched tea for food processing and health supplement production.

Hair Se Is a Sensitive Biomarker to Monitor the Effects of Se Supplementation in Elderly.

It is rapidly increasing to have selenium (Se) supplementation for urban elderly population in China since they are facing a widespread deficiency daily Se intake. However, until now, there is no low-cost, non-invasive, rapid, and reliable method to monitor the health improvement or risk for elderly Se-supplemented population in China. The present cross-sectional study (229 participants with older than 55 years old) performed in Beijing, China, revealed that the Se concentrations of non-supplementer users (n = 27) were 55 ± 23 µg/L in urine, 139.9 ± 102.3 µg/L in serum, and 487.6 ± 158.7 µg/kg in hair. But a significant increase on hair Se concentrations (615.4 ± 238.8 µg/kg) was observed for Se supplementer users (n = 202) (p < 0.05); there were no significant statistical differences in serum and urine between the Se-supplemented (n = 202) and Se non-supplemented groups (n = 27). This indicated the hair Se levels could be a more sensitive biomarker for Se-supplemented elderly population. Participants who consumed Se supplements for 7-12 months had the highest Se status based on hair and serum Se concentrations (p < 0.05). The present study also revealed that most elderly adults in Beijing just need to supplement 50 µg Se per day to achieve Se plateau status. Furthermore, hair Se levels were positively related with triglycerides/TG levels (p < 0.05) but not body mass index/BMI, total cholesterol/TC, and low-density lipoprotein cholesterol/LDL, implicating Se supplementation for Se sufficiency baseline in elderly population in Beijing likely posed health risk, especially on TG because of excessive Se oxidation stress. An ongoing monitoring of Se status via hair is still warranted to prevent future Se deficiency or excess in China.

The influence of sea animals on selenium distribution in tundra soils and lake sediments in maritime Antarctica.

The biogeochemical behavior of selenium (Se) has been extensively studied in Se-enriched or Se contaminated soils at low and middle latitudes. However, the Se distribution patterns have not been studied in tundra ecosystems of remote Antarctica. Here, the soils/sediments were collected from penguin and seal colonies, their adjacent tundra and lakes, tundra marsh, human-activity areas, normal tundra and the periglacial in maritime Antarctica, and total Se and seven operationally defined Se fractions were analyzed. Overall the regional distribution of Se levels showed high spatial heterogeneity (coefficient of variation, CV = 114%) in tundra soils, with the highest levels in penguin (mean 6.12 ± 2.66 µg g-1) and seal (mean 2.29 ± 1.43 µg g-1) colony soils, and the lowest in normal tundra soils and periglacial sediments (<0.5 µg g-1). The contribution rates of penguins and seals to tundra soil Se levels amounted to 91.7% and 78.0%. The lake sediment Se levels (mean 2.15 ± 0.87 µg g-1) close to penguin colonies were one order of magnitude higher than those (mean 0.49 ± 0.87 µg g-1) around normal tundra. Strong positive correlations (p < 0.01) of Se concentrations between lake sediments and adjacent tundra soils, and lower Se: P (<0.001) and S: P (<1) ratios in the lake sediments close to penguin colonies, indicated the infiltration or leaching of penguin guano as the predominant Se source in lake sediment. The Se species in penguin and seal guano were dominated by SeCys2 (76.6%) and SeMet (73.5%), respectively. The evidence from the predominant proportions of total organic matter-bound Se (Seom, 67%-70% of total Se) in penguin or seal colony soils further supported penguin or seal guano had a great influence on the distribution patterns of Se fractions in the tundra. This study confirmed that sea animal activities transported substantial amount Se from ocean to land, and significantly altered the biogeochemical cycle of Se in maritime Antarctica.

Selenium Effect Threshold for Soil Nematodes Under Rice Biofortification.

Crop biofortification with inorganic selenium (Se) fertilizer is a feasible strategy to improve the health of residents in Se-deficient areas. For eco-friendly crop Se biofortification, a comprehensive understanding of the effects of Se on crop and soil nematodes is vital. In this study, a rice pot experiment was carried out to test how selenite supply (untreated control (0), 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 100, or 200 mg Se kg-1) in soil affected rice growth, rice Se accumulation, and soil nematode abundance and composition. The results showed that selenite supply (5-200 mg kg-1) generally increased the number of rice tillers, rice yield, and Se concentrations in rice grains. In soil under 10 mg kg-1 Se treatment, the genus composition of nematodes changed significantly compared with that in the control soil. With increased Se level (> 10 mg kg-1), soil nematode abundance decreased significantly. Correlation analysis also demonstrated the positive relationships between soil Se concentrations (total Se and bioavailable Se) with rice plant parameters (number of rice tillers, rice yield, and grain Se concentration) and negative relationships between soil Se concentrations (total Se and bioavailable Se) with soil nematode indexes (nematode abundance and relative abundance of Tobrilus). This study provides insight into balancing Se biofortification of rice and soil nematode community protection and suggests the effective concentrations for total Se (1.45 mg kg-1) and bioavailable Se (0.21 mg kg-1) to soil nematode abundances at 20% level (EC20) as soil Se thresholds. At Se concentrations below these thresholds, rice plant growth and Se accumulation in the grain will still be promoted, but the disturbance of the soil nematodes would be negligible.