Se Concentrations Research Articles

PSLBII-17 Supplementation with organic versus inorganic selenium during pregnancy to support ewe and lamb health

Abstract Selenium (Se) is essential for optimal ovine health and production, and sheep raised on Se-deficient soils can be vulnerable to Se deficiencies that can affect immune function. Organic or inorganic forms of Se supplementation can remedy these consequences. While inorganic Se is less costly, organic Se is more bioavailable and may be more efficient in providing Se to ewes and lambs. The objectives of this study were to determine how organic versus inorganic Se supplementation affects ewe Se status, Se transfer from ewes to lambs, and the antibody-mediated immune response and dermal hypersensitivity response (DHR) of ewes and their lambs. Dorset-Rideau ewes (n = 100) were enrolled in a randomized complete block design study. From gestation d (gd) 110 to postpartum d (ppd) 50, ewes were fed either a Se-deficient diet and supplemented with no Se, 0.3 mg inorganic Se, or 0.3 mg or 0.6 mg organic Se. Sera were collected on gd 110, 130, 140, and ppd 10 and 50 to determine ewe Se status. On gd 110 and 120, ewes received an intramuscular injection of 0.5 mg ovalbumin (OVA) antigen, and on gd 130 the DHR to OVA was assessed by measuring change in skinfold thickness 0, 6, 24 and 48 h post intradermal injection. To measure the transfer of Se from ewe to lamb, a subset of lambs was euthanized at ppd 10, and longissimus dorsi muscle samples were collected and analyzed for Se content. On ppd 20 and 30, lambs received an intramuscular injection of 0.5 mg hen egg white lysozyme (HEWL) antigen, and on ppd 40 the DHR to HEWL was assessed using the aforementioned protocol. Analysis of ewe sera showed a positive correlation between organic Se supplementation and greater Se concentrations (P < 0.01). Moreover, statistical analyses of the DHR results using a generalized least squares linear model (RStudio) indicate that Se supplementation increased the immune response compared with the non-supplemented ewes (P < 0.01). However, no significant differences between organic and inorganic Se supplementation were found. In lambs, greater ewe Se supplementation resulted in greater Se muscle content (P > 0.01). and organic Se supplementation to ewes significantly increased lamb Se muscle content compared with inorganic Se supplementation (P > 0.01). Finally, analyses of the lamb DHR showed that maternal organic Se supplementation improved the lamb immune response compared with the control group (P > 0.05). Therefore, organic Se supplementation optimally enhances ewe and lamb Se status and their adaptive immune response compared with the inorganic and control groups. This knowledge will guide optimal ewe Se-supplementation choices during pregnancy and postpartum, thus promoting lamb and ewe health.

208 Assessment of a new oral neonatal supplement for lambs

Abstract The objective of this study was to evaluate an easy to administer and economical oral nutritional supplement for neonatal lambs. Neonates are at risk of nutrient deficiencies because of maternal deficiencies, minimal body stores at birth and decreased nutritional intake. The pre-ruminant lamb relies solely on milk for adequate immunity and nutrition until they begin ingesting forages. Insufficiencies can lead to increased mortality and morbidity. However, deficiencies in the ewe are common due to variation in management, feeding and health protocols. A total of 10 lambs (5 sets of twins) were enrolled into the study. The lambs were divided into two groups (one twin from each set) received a treatment of an oral vitamin-mineral supplement (VitaFerst-Care) 3 mL and the control lambs a saline solution of 3 mL, all at 3 d of age (d0). Blood samples were collected, prior to, and again following supplementation (d 0, d 21) by jugular venipuncture. Vitamin A, vitamin E, iron (Fe) and selenium (Se) concentrations were determined in blood serum/plasma of the lambs by HPLC. Kidney and liver function markers were analyzed using HESKA DC5X veterinary analyzer to confirm the safety of the supplement. Variables tested included alkaline phosphatase (ALP), alanine aminotransferase (ALT), blood urea nitrogen (BUN), creatinine (CREA), glucose (GLU), total protein (TP), total bilirubin (T-BILI), albumin (ALB), phosphorus (PHOS), calcium (CA), cholesterol (CHOL), and gamma-glutamyl transferase (GGT). All lambs remained with their mothers. The average difference was calculated between d 21 and d 0 (baseline) for treated versus control animals for vitamin A, vitamin E, Se, and Fe. Significance was calculated using a two-tailed student’s t-test where P < 0.10 between d 21 control and treated animals. Control animals had an average vitamin E plasma concentration of 1.168 + 0.355 ppm on d 21, whereas treated animals had an average of 1.547 + 0.559 ppm. Significance was calculated at P = 0.09. Vitamin A, Fe and Se concentrations did not reach significance. Kidney and liver panel checks for animals in each group were not concerning. Future studies should look at modifying first and second sampling timepoints to be closer together. Based on results in calves with a similar study design, shortening the time between treatment and second sampling would give a clearer picture of how the neonatal supplement influenced the nutritional status of the treatment versus control animals.

Identification, characterization, and expression analysis of WRKY transcription factors in Cardamine violifolia reveal the key genes involved in regulating selenium accumulation

BackgroundCardamine violifolia is a significant Brassicaceae plant known for its high selenium (Se) accumulation capacity, serving as an essential source of Se for both humans and animals. WRKY transcription factors play crucial roles in plant responses to various biotic and abiotic stresses, including cadmium stress, iron deficiency, and Se tolerance. However, the molecular mechanism of CvWRKY in Se accumulation is not completely clear.ResultsIn this study, 120 WRKYs with conserved domains were identified from C. violifolia and classified into three groups based on phylogenetic relationships, with Group II further subdivided into five subgroups. Gene structure analysis revealed WRKY variations and mutations within the CvWRKYs. Segmental duplication events were identified as the primary driving force behind the expansion of the CvWRKY family, with numerous stress-responsive cis-acting elements found in the promoters of CvWRKYs. Transcriptome analysis of plants treated with exogenous Se and determination of Se levels revealed a strong positive correlation between the expression levels of CvWRKY034 and the Se content. Moreover, CvWRKY021 and CvWRKY099 exhibited high homology with AtWRKY47, a gene involved in regulating Se accumulation in Arabidopsis thaliana. The WRKY domains of CvWRKY021 and AtWRKY47 were highly conserved, and transcriptome data analysis revealed that CvWRKY021 responded to Na2SeO4 induction, showing a positive correlation with the concentration of Na2SeO4 treatment. Under the induction of Na2SeO3, CvWRKY021 and CvWRKY034 were significantly upregulated in the roots but downregulated in the shoots, and the Se content in the roots increased significantly and was mainly concentrated in the roots. CvWRKY021 and CvWRKY034 may be involved in the accumulation of Se in roots.ConclusionsThe results of this study elucidate the evolution of CvWRKYs in the C. violifolia genome and provide valuable resources for further understanding the functional characteristics of WRKYs related to Se hyperaccumulation in C. violifolia.

210 Maternal dietary organic selenium improves selenium status in neonatal lambs compared with single maternal or neonatal injection of inorganic selenium

Abstract The objective of this study was to compare the efficiency of three industry standard practices for improving the selenium (Se) status in neonatal lambs. Pregnant Polypay ewes (n = 27) at around 40 d pre-partum were enrolled in the study. The ewes were fed with grass silage and grain and, at 40 d from expected lambing, randomly allocated to one of three groups: 1) a single injection of 25 g sodium selenate as BO-SE/kg body weight (BW) at 4 wk before expected parturition (Inj-E) and not injection in the lambs; 2) no injection of BO-SE in the ewe but injection of 4.38 mg sodium selenite as BO-SE at 3 d of life of the lambs (Inj-L); and 3) no injection of BO-SE to the ewes or lambs but the ewes were fed 3.6 mg Se/day as Se-yeast (Yst-E) through the duration of the study (40 d prepartum + 30 d postpartum). Lambs were nursed by their own dams for 30 d without access to other feed (i.e., only milk). Blood was collected from the lambs at d 3 and 10 of life to measure 14 minerals, including Se, using ICP-MS. Glutathione peroxidase activity (GPx) was measured using a commercial kit. Data were analyzed using a GLIMMIX of SAS with an ARH covariance with treatment and time as the main effect, with lambs nested in ewe as a random effect. The number of lambs/ewes was used as a covariate. The injection of BO-SE in the ewes did not affect concentrations of Se in the lambs at birth, as there were no differences in whole blood Se between lambs in Inj-E and lambs in Inj-L at 3 d of life (i.e., before Inj-L received the BO-SE). The injection of BO-SE did not affect the level of Se in the whole blood of lambs 7 d after the injection compared with baseline (i.e., 3 d of life). Consequently, there was no difference in whole blood Se between lambs in Inj-E and Inj-L groups (177 vs. 167 ng/mL, respectively). However, injection of Se in pre-parturient dams did improve GPx activity in offspring (P = 0.04). Lambs in Yst-E had significantly greater concentrations of Se in whole blood compared with the other two groups at both 3 and 10 d of life (281 ng/mL; P < 0.001). Our data demonstrate that the typical industry standard approach of injecting inorganic Se in prepartum ewes or neonatal lambs is ineffective while feeding Se-yeast to dams was effective in improving Se status in lambs.

49 Crossing-talk between micronutrient and macronutrient metabolism: Implication in health and disease

Abstract Recent goals of swine ration formulation have evolved from preventing nutritional deficiency diseases and maximizing growth performance to optimizing immune function and disease resistance with least climate impact. Thus, certain micronutrients such as selenium (Se) are widely considered to be health beneficial at dietary concentrations above nutrient requirements. During the past decade, we have conducted a number of experiments to determine impacts and mechanisms of dietary Se concentrations (0.03 to 1 or 3 mg/kg) on metabolism of carbohydrate, lipid, and protein in pigs from growing to finishing. Strikingly, pigs fed high-Se diets developed hyperinsulinemia and insulin resistance. Those pigs also had increased lipid, protein, saturated fatty acids (myristic, palmitic, stearic, and behenic acids), and aspartic acid, glutamine, and alanine and decreased polyunsaturated fatty acids (dihomo-γ-linolenic, oleic, α-linolenic, and eicosatrienoic acids) in the liver and(or) adipose tissues. The high-Se diets increased and decreased amounts of 5 and 2 selenoproteins, respectively, in tissues of pigs. These effects were associated with down-regulated insulin signaling (INSR and AKT), glycolysis (glucokinase) and gluconeogenesis (PEPCK) and up-regulated lipogenesis (FOXO1, SREBP1, ACC and FAS), and protein synthesis (mTOR and RPS6/S6). In contrast, high dietary fat intakes up- or down-regulated expressions of all selenoproteins except for TXNRD2 and TXNRD3 and showed a strong effect on expressions of DIO2, GPX6, and SELENOK. These induced selenogenome expression changes were associated with increased serum malondialdehyde and plasma concentrations of tumor necrosis factor alpha and interleukin-6, along with risk of obesity and chronic inflammation. Altogether, metabolisms of micronutrients and macronutrients in pigs are coordinated through interdependent and mutually regulated crossing talks at tissue, cellular, biochemical, and signal levels.

Overcoming Ion Trapping in Chevrel Phase Compounds via Tailored Anion Substitution: An Integrated Study of Theory, Synthesis, and In Operando Techniques for Reversible Aqueous Zn-Ion Batteries.

Sustainable batteries are key for powering electronic devices of the future, with aqueous zinc-ion batteries (AZIBs) standing out for their use of abundant, readily available elements, and safer production processes. Among the various electrode materials studied for AZIBs, the Chevrel Phase, Mo6S8 has shown promise due to its open framework, but issues with zinc ion trapping have limited its practical application. In this work, we employed computational methods to investigate the insertion-deinsertion mechanism in a series of isostructural Mo6S8-xSex (x = 0-8) solid solutions as materials that could balance the gravimetric capacity and reversible cycling for AZIBs. Density functional theory (DFT) calculations revealed that increasing the Se content would reduce the binding energy of Zn within the structures, enabling Zn deinsertion compared to the Mo6S8 structure. Experiments confirmed the formation of Mo6S8-xSex (x = 0-8) solid solutions, and electrochemical testing showed improved reversibility of Zn insertion/deinsertion as the amount of Se increased, consistent with the computational predictions. Furthermore, combined in operando X-ray diffraction and electrochemical studies revealed a continuous, gradual Zn-insertion process into Mo6S4Se4, in stark contrast to the abrupt phase changes observed upon Zn insertion in Mo6S8 and Mo6Se8. DFT calculations attributed the stabilization of Zn0.5Mo6S4Se4 as a prime reason for preventing phase separation, making Se-substituted compounds promising materials for high-performance AZIBs. Overall, this interdisciplinary approach, integrating computational modeling, materials synthesis, and advanced characterization techniques, offers a pathway for fine-tuning anion chemistry that can help create high-performance electrode materials for sustainable energy storage technologies.

Exogenous selenium mitigates cadmium uptake and accumulation in two rice (Oryza sativa L.) varieties in cadmium-contaminated soil

Rice grown in cadmium (Cd)-contaminated soil, is a potential threat to human health, but exogenous selenium (Se) application on rice can mitigate Cd toxicity. However, the mechanisms underlying Se mitigation of Cd stress in ratoon rice (RR) are still poorly understood. We conducted a pot experiment with moderate Cd-contaminated yellow–brown paddy soil on two rice varieties ‘Taoyouxiangzhan’ (TX) and ‘Liangyou 6326’(LY). For all treatments, 1.0 mg kg−1 sodium selenite solution was added to soil. Treatment T1 was sodium selenite only, and in the other treatments 100 mg L−1 Se solution was sprayed on the leaves at seedling stage (T2), at tillering stage (T3), and in early anthesis stage (T4). Se treatments decreased Cd accumulation in rice grains and herbage. Under foliar spraying 100 mg L−1 Se at the seedling + 1.0 mg kg−1 Se in soil (T2), leaf Cd content decreased 16.95% in the current season and grains content decreased 46.67% in the subsequent season. Furthermore, grain Se content increased 0.94 mg kg−1 for the TX variety combined with the analysis of Cd bio-accumulation factor in grains, and Se treatments effectively decreased Cd grain concentrations due to reduced Cd translocation from roots to grains. TX variety rice showed a more pronounced response to Se treatments than LY.

Estimated daily intake and health risk assessment of total and organic selenium in crops across areas with different selenium levels

BackgroundThe health risk of Se has gained significant attention. Previous studies mainly focused on the health risk of total Se in high-Se area. Less attention has been paid to the health risk of organic selenium in areas with varying selenium levels. MethodsA total number of 109 crop samples (edible parts) were collected in Langao County, Shannxi Province, China from 2018 to 2020, including 42 corn, 18 rice, 9 sweet potato, 25 potato, 12 radish, and 3 eggplant samples. The hydride generation atomic fluorescence spectrometry (HG-AFS) method was used to determine the total and organic Se contents. Result and conclusion(1) Corn (2.82 mg/kg), rice (0.44 mg/kg), potato (6.56 mg/kg), and eggplant (0.77 mg/kg) in high-Se area, as well as sweet potato (1.07 mg/kg) and radish (4.28 mg/kg) in medium-Se area, exhibited the highest total Se content among all crops in this county, and 5–328 times higher than the values of Se-enriched standard (2) The average daily intake of total/organic Se of residents in high-Se area reached 676/449 μg/day, which was 1–4 times higher than levels observed in medium-Se area (419/257 μg/day) and low-Se area (196/128 μg/day). The organic Se daily intakes from dietary combinations of rice + radish and rice + eggplant in high-Se area lower than 400 μg/day, which could be safely consumed. The organic Se daily intakes from dietary combinations of sweet potato + radish and sweet + eggplant in medium-Se area higher than 400 μg/day, which could not be safely consumed. The total / organic Se daily intakes of all dietary combinations in low-Se area lower than 400 μg/day, which could be safely consumed. (3) The health risk associated with crops might be overestimated due to the higher non-carcinogenic risk attributed to total Se compared to organic Se. The present study demonstrated that daily intake and health risk of total and organic Se in crops across areas with different Se levels varied significantly.

Determination of some antioxidant vitamins and trace elements in selected grains, fruits and vegetables commercially sold in Eke Awka market, Awka, Anambra State, Nigeria

Six samples from cucumber (Cucumis sativus), apple (Malus domestica), cabbage (Brassica oleracea), Tiger nuts (Cyperus esculentus), Beans (Phaseolus vulgaris), Green peas (Pisum sativum) were purchased from Eke Awka market, Awka in Anambra state, and evaluated for some antioxidant vitamins using standard method. The concentration of the Trace metals namely Fe,Zn, Cu, Mn, Se, Pb, Cd and Ni were assessed using Atomic Absorption Spectrophotometer. The concentration of each trace metal in the sample was determined and compared with the permissible levels set by the Food and Agricultural Organization/World Health Organization. Antioxidant vitamins results showed that cabbage has the highest Vitamin A level, green peas the highest Vitamin C level while tigernuts has the highest Vitamin E level. The result of trace metal analysis showed that the concentration of Fe, Zn, Cu, Mn, Se, Pb, Cd and Ni in the six selected samples were lower or within the recommended permissible limit. This indicates that the samples are nontoxic and also safe for human consumption because they are within the acceptable limit that is not dangerous to health as recommended by World Health Organization /Food and Agriculture Organization. Keywords: Trace element, Antioxidant vitamins, Atomic Absorption Spectrophotometer, Grains, Fruits, Vegetables

The potency of Monascus purpureus to achieve the transformation from inorganic selenium into organic selenium during the fermentation process

Selenium (Se), as an essential element for the human body, cannot be produced by itself, making Se-rich products research a current hotspot. Microorganisms are common Se-rich carriers and previous experiments mainly focused on yeast and lactic acid bacteria, lacking mold. In this study, the total Se and organic Se content in Monascus purpureus (M. purpureus) were determined by a liquid chromatography-atomic fluorescence spectrometry after fermentation, applying inorganic sodium selenite as exogenous Se. The research results indicated that M. purpureus successfully converted inorganic Se into organic Se, with an organic Se to total Se ratio of 30.50%, 36.14%, 39.94%, 46.18%, and 53.00% at 2, 4, 6, 8, and 10 mg/L sodium selenite, respectively. The proportion of Se-protein (28.04%–47.33%) was highest in organic Se, especially water-soluble Se-protein, followed by Se-polysaccharide (3.80%–5.07%) and Se-nucleic acid (1.84%–3.07%). Furthermore, Se-enriched treatment did not significantly alter the morphology or structure of M. purpureus, while enriching the types and content of volatile components in the fermentation broth. Thus, this study was expected to lay the foundation for the development and utilization of Se-rich M. purpureus products.

Effects of high-dose selenium-enriched Saccharomyces cerevisiae on growth performance, antioxidant status, tissue fat content and selenium concentration, and selenoenzyme mRNA expression in chicks

Selenium-enriched Saccharomyces cerevisiae (SSC) as organic selenium (Se) has been shown to have better advantages and is approved for use in animal feed rather than inorganic Se, however, there is little available data on the toxic effects of SSC on poultry. The present study was conducted to investigate the effects of high-dose SSC on growth performance, antioxidant status, tissue fat content and Se concentration, and selenoenzyme mRNA expression in chicks. A total of 500, 1-day-old SPF chicks were randomly divided into 5 groups with 10 replicates of 10 chicks each. Group 1 served as a control and was fed a basal diet supplemented with 0.15 mg/kg Se from sodium selenite (SS), group 2 was fed the basic diet supplemented with 1.5 mg/kg Se from SS, while groups 3, 4, and 5 were fed the basal diet supplemented with 1.5, 5 and 10 mg/kg Se from SSC, respectively. The results showed that SS and SSC supplementation significantly affected the average daily feed intake (ADFI), feed/gain ratio (FCR), glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities, total antioxidant capacity (T-AOC), malondialdehyde (MDA) content, tissue fat content and Se concentration, and GPx1 and GPx4 mRNA levels compared with the control group (P < 0.05). Compared with group 2, group 3 exhibited higher GPx and SOD activities, tissue Se concentration, and lower MDA content on d 30, and higher Se concentration, GPx1 mRNA levels in liver and breast muscle and GPx4 mRNA levels in liver and thigh muscle, and lower MDA content on d 60 (P < 0.05). The results of correlation analysis showed that high-dose SSC supplementation was positively correlated with AFDI, FCR, MDA content, and tissue Se concentration, and negatively correlated with GPx and SOD activities, T-AOC, GPx1 and GPx4 mRNA levels in tissues. In conclusion, up to 1.5 mg/kg Se from SSC in diet may be a safe concentration for chicks that exhibited better biological effects than SS, the toxic effects of high-dose SSC supplementation mainly exhibited growth decrease, peroxidation and lipid metabolism disturbance, and became stronger with the increase of dietary Se levels.

Selenium, Zinc, and Plasma Total Antioxidant Status and the Risk of Colorectal Adenoma and Cancer.

Selenium (Se), zinc (Zn), and copper (Cu) are known to be involved in carcinogenesis and participate in the defence against reactive oxygen species (ROS). This study aimed to evaluate the clinical utility of serum Se, Zn, and Cu concentrations and plasma total antioxidant status (TAS) in the diagnosis of colorectal cancer (CRC) and colorectal adenoma (CRA) in a population of low Se and borderline Zn status. Based on clinical examination and colonoscopy/histopathology, the patients (n = 79) were divided into three groups: colorectal cancer (n = 30), colorectal adenoma (n = 19), and controls (CONTROL, n = 30). The serum Se concentration was lower in the CRC group than in the CRA group (by 9.1%, p < 0.0001) and the CONTROL group (by 7.9%, p < 0.0001). In turn, the serum Zn concentration was decreased in the CRA group (by 17.9%, p = 0.019) when compared to the CONTROL group. Plasma TAS was lower in the CRC group (by 27.8%, p = 0.017) than in the CONTROL group. In turn, the serum Zn concentration was decreased in the CRA group when compared to the CONTROL group. Plasma TAS was lower in the CRC group than in the CONTROL group. ROC (receiver operating characteristic) curve analysis revealed that the Se level was of the highest diagnostic utility for the discrimination of the CRC group from both the CRA group (area under ROC curve (AUC) 0.958, sensitivity 84.21%, specificity 100%) and the CONTROL group (AUC 0.873, sensitivity 100%, specificity 66.67%). The Zn and TAS levels were significantly accurate in the differentiation between the groups. An individualised risk of colorectal adenoma and cancer approach could comprise Se, Zn, and TAS assays in the population.

Se‐dopant Modulated Selective Co‐Insertion of H+ and Zn2+ in MnO2 for High‐Capacity and Durable Aqueous Zn‐Ion Batteries

AbstractMnO2 is commonly used as the cathode material for aqueous zinc‐ion batteries (AZIBs). The strong Coulombic interaction between Zn ions and the MnO2 lattice causes significant lattice distortion and, combined with the Jahn–Teller effect, results in Mn2+ dissolution and structural collapse. While proton intercalation can reduce lattice distortion, it changes the electrolyte pH, producing chemically inert byproducts. These issues greatly affect the reversibility of Zn2+ intercalation/extraction, leading to significant capacity degradation of MnO2. Herein, we propose a novel method to enhance the cycling stability of δ‐MnO2 through selenium doping (Se−MnO2). Our work indicates that varying the selenium doping content can regulate the intercalation ratio of H+ in MnO2, thereby suppressing the formation of ZnMn2O4 by‐products. Se doping mitigates the lattice strain of MnO2 during Zn2+ intercalation/deintercalation by reducing Mn−O octahedral distortion, modifying Mn−O bond length upon Zn2+ insertion, and alleviating Mn dissolution caused by the Jahn–Teller effect. The optimized Se−MnO2 (Se concentration of 0.8 at.%) deposited on carbon nanotube demonstrates a notable capacity of 386 mAh g−1 at 0.1 A g−1, with exceptional long‐term cycle stability, retaining 102 mAh g−1 capacity after 5000 cycles at 3.0 A g−1.

Arsenic, selenium, and mercury speciation in hypersaline lakes of the Andean Altiplano: Link between extreme levels and biodiversity repartition

Arsenic (As) and mercury (Hg) are highly toxic contaminants whereas selenium (Se) is both an essential trace element and potentially harmful at higher concentrations. The hyper-saline lakes of southern Bolivian Altiplano, which are ecological niches for endemic species, are also expected to be enriched in these toxic trace elements. The biogeochemistry of As, Hg, and Se in such high-altitude extreme environments (e.g., high UV radiation and salt content) remains poorly understood. In this study, we investigated the concentrations and chemical forms (speciation) of As, Hg, and Se in sediment, water, and air samples of Lagunas Colorada (LC), Verde (LV), and Blanca (LB) in the South Lipez region (>4200 m a.s.l.). We compared them with the repartition of biodiversity (invertebrates, algae, and bacteria). Extreme As concentrations were found in water (up to 82 mg L−1), and the main As species was inorganic As(V), with neither biogenic methylated As nor volatile As forms being detected in water and air, respectively. Se concentrations in water were of 0.1 to 1.4 μg L−1, and Se existed under different redox states, i.e., Se(IV), Se(VI), and reduced Se (0, -II), including biogenic methylated Se(-II) (trimethyl selenonium). Volatile Se compounds (e.g., dimethyl selenide) were detected in water and air samples. Hg was enriched in the surface water (6 to 30 ng L−1) compared to other regional water bodies, and a significant amount of methyl-Hg and gaseous Hg(0) was detected. The drastic disparity between As, Se and Hg concentrations and speciation between lakes has important implications for their cycling in these extreme aquatic systems. While As mostly accumulated in its oxidized and non-volatile form, Hg and Se concentrations can be controlled by significant conversion to reduced and methylated forms, allowing efficient evasion to the atmosphere. Finally, the salinity, including major ions, and high levels of As were among the main drivers of biodiversity repartition between lakes.

Selenium availability in tea: Unraveling the role of microbiota assembly and functions

Tea (Camellia sinensis (L.) O. Kuntze) plants have a strong ability to accumulate selenium (Se). However, the question of how tea plants affect Se availability has received little attention. In this study, five tea cultivars, including Soubei (SB), Aolǜ (AL), Longjing43 (LJ), Zhaori (ZR) and Fenglǜ (FL), were chosen for the study. Quantitative Microbial Ecology Chip and high-throughput sequencing were used to explore the effects of five tea cultivars on soil functions, microbial community structures and Se availability. The results showed that the total soil Se content in the FL garden was lower compared to LJ and SB gardens, whereas available Se was highest in the FL garden. Based on the Bray-Curtis distances, tea cultivar was the main factor affecting bacterial and fungal community structures. The abundance of functional genes concerning carbon, nitrogen, phosphorus and sulfur cycling processes varied among tea gardens. The higher soil NH4+ and NO3− contents, and higher abundance of functional genes like nifH, amoA1 and narG, whereas lower total nitrogen in the FL garden than in the AL and LJ tea gardens demonstrated that the FL tea plants induced microbes to accelerate soil nitrogen cycling processes. Dominant microbes that positively related with functional genes like nifH, narG, and amoA1 were also positively related with the available Se content. In conclusion, tea cultivars could regulate soil functions through affecting microbial community structures and then affecting the soil Se availability. The soil nitrogen cycle processes are suggested to be closely related with Se transformation in tea gardens.

Understanding the electrochemical processes of SeS2 positive electrodes for developing high-performance non-aqueous lithium sulfur batteries

SeS2 positive electrodes are promising components for the development of high-energy, non-aqueous lithium sulfur batteries. However, the (electro)chemical and structural evolution of this class of positive electrodes is not yet fully understood. Here, we use operando physicochemical measurements to elucidate the dissolution and deposition processes in the SeS2 positive electrodes during lithium sulfur cell charge and discharge. Our analysis of real-time imaging reveals the pivotal role of Se in the SeS2 nucleation process, while S enables selective depositions. During the initial discharge, SeS2 converts into Se and S separately, with the dissolved Se acting as nucleation sites due to their lower nucleation potential. The Se effectively catalyzes the growth of S particles, resulting in improved lithium sulfur battery performance compared to cells using positive electrodes containing only Se or S as active materials. By adjusting the Se-to-S ratio, we demonstrate that a low concentration of Se enables uniform catalytic sites, promotes the homogeneous distribution of S and favours improved lithium sulfur battery performance.

Temperature-Gradient Solution Deposition Amends Unfavorable Band Structure of Sb2(S,Se)3 Film for Highly Efficient Solar Cells.

Band structure of a semiconducting film critically determines the charge separation and transport efficiency. In antimony selenosulfide (Sb2(S,Se)3) solar cells, the hydrothermal method has achieved control of band gap width of Sb2(S,Se)3 thin film through tuning the atomic ratio of S/Se, resulting in an efficiency breakthrough towards 10 %. However, the obtained band structure exhibits an unfavorable gradient distribution in terms of carrier transport, which seriously impedes the device efficiency improvement. To solve this problem, here we develop a strategy by intentionally regulating hydrothermal temperature to control the chemical reaction kinetics between S and Se sources with Sb source. This approach enables the control over vertical distribution of S/Se atomic ratio in Sb2(S,Se)3 films, forming a favorable band structure which is conducive to carrier transport. Meanwhile, the adjusted element distribution not only ensures the uniformity of grain structure, but also increases the Se content of the films and suppress sulfur vacancy defects. Ultimately, the device delivers a high efficiency of 10.55 %, which is among the highest reported efficiency of Sb2(S,Se)3 solar cells. This study provides an effective strategy towards manipulating the element distribution in mixed-anion compound films prepared by solution-based method to optimize their optical and electrical properties.

Selenium Treatment Ameliorates the Adverse Effects Caused by Dynamin Gene Knockdown in Bombyx mori.

Our previous research reported the influence of 50 μM selenium (Se) on the cytosolization (endocytosis) pathway, which in turn stimulates the growth and development of Bombyx mori. Lately, dynamin is recognized as one of the key proteins in endocytosis. To explore the underlying mechanisms of Se impact, the dynamin gene was knocked down by injecting siRNAs (Dynamin-1, Dynamin-2, and Dynamin-3). This was followed by an analysis of the target gene and levels of silk protein genes, as well as growth and developmental indices, Se-enrichment capacity, degree of oxidative damage, and antioxidant capacity of B. mori. Our findings showed a considerable decrease in the relative expression of the dynamin gene in all tissues 24 h after the interference and a dramatic decrease in the silkworm body after 48 h. RNAi dynamin gene decreased the silkworm body weight, cocoon shell weight, and the ratio of cocoon. In the meantime, malondialdehyde level increased and glutathione level and superoxide dismutase/catalase activities decreased. 50 μM Se markedly ameliorated these growth and physiological deficits as well as decreases in dynamin gene expression. On the other hand, there were no significant effects on fertility (including produced eggs and laid eggs) between the interference and Se treatments. Additionally, the Se content in the B. mori increased after the dynamin gene interference. The dynamin gene was highly expressed in the silk gland and declined significantly after interference. Among the three siRNAs (Dynamin-1, Dynamin-2, and Dynamin-3), the dynamin-2 displayed the highest interference effects to target gene expression. Our results demonstrated that 50 μM Se was effective to prevent any adverse effects caused by dynamin knockdown in silkworms. This provides practical implications for B. mori breeding industry.

Therapeutic Efficacy of Selenium Pre-treatment in Mitigating Cadmium-Induced Cardiotoxicity in Zebrafish (Danio rerio)

Cardiovascular diseases are a rampant public health threat. Environmental contaminants, such as Cadmium (Cd), a toxic metal, are risk factors for cardiovascular diseases. Given that human exposure to Cd is increasing, there is a need for therapies to ameliorate Cd toxicity. Selenium (Se), an essential trace element, has been proposed to rescue the effects of Cd toxicity, with mixed effects. Se's narrow therapeutic window necessitates precise dosing to avoid toxicity. Here, we assessed the effects of various waterborne Cd and Se concentrations and sequences on cardiac function using zebrafish (Danio rerio). We showed that Cd induced pericardial edemas and modified heart rates in zebrafish larvae in a concentration-dependent manner. To identify the therapeutic range of Se for Cd-induced cardiotoxicity, zebrafish embryos were treated with 0, 10, 50, 100, 150, or 200 μg/L Se for 1–4 days prior to exposure to 2.5 and 5 μg/L Cd. We found that a 50 µg/L Se pre-treatment before 2.5 μg/L Cd, but not 5 μg/L Cd, reduced the prevalence of pericardial edemas and ameliorated Cd-induced bradycardia in zebrafish. Zebrafish exposed to 10 and 50 μg/L of Se for up to 4 days showed typical heart morphology, whereas other Se-exposed and control fish presented pericardial edemas. Longer Se pre-treatment durations led to fewer incidences of pericardial edemas. Overall, this study highlights the importance of optimizing Se concentrations and pre-treatment periods to harness its protective effects against Cd-induced cardiotoxicity. These findings provide insights into potential therapeutic strategies for reducing Cd-related cardiovascular damage in humans.Graphical

Bioaccumulation and biotransformation of selenium nanoparticles in soybean and natto, and the bioaccessibility of multi-elements and amino acids

Soybean is a food crop with strong selenium (Se) enrichment ability. Selenium nanoparticles (SeNPs) are a low-toxic Se source. To develop strategies in SeNPs biofortification of soybean and natto, the effects of Se enrichment and natto fermentation on selenoamino acids, mineral elements, free amino acids, γ-polyglutamic acid, nattokinase, and bioaccessibility were investigated. Soybean grains were able to convert SeNPs into selenomethionine (SeMet). Selenium enrichment and natto fermentation influenced the enrichment and distribution of multi-elements in soybean, as well as the composition of free and bound amino acids. Selenium enrichment had no significant effect on the bioaccessibility of amino acids. After natto fermentation, the bioaccessibility of SeMet, Fe, Mn, Cu, and Zn in the gastrointestinal tract increased significantly by 10.1–18.9 %. These findings indicate that SeNPs can enhance the Se content of soybean grains, and natto fermentation can further improve the nutritional quality of Se-enriched soybean.