Selenium Accumulation Research Articles

Mortality, growth and metabolic responses by 1H-NMR-based metabolomics of earthworms to sodium selenite exposure in soils

The rapid development of selenium-enriched agriculture leads to the accumulation of selenium in the soil, which has an adverse impact on terrestrial ecosystems. In the present study, the mortality, growth inhibition rate and metabolism of earthworms were examined to investigate the toxicological effects of sodium selenite (Na2SeO3) on earthworms (Eisenia fetida) after exposuring for 14 days (d). We used 1H-NMR-based metabolomics to identify sensitive biomarkers and explored the metabolic responses of earthworms exposed to Na2SeO3. The mortality and growth inhibition rate of earthworms exposed to 70 and 90 mg/kg Na2SeO3 were significantly higher than the rate of control group. The LC50 (the median lethal concentration) of Na2SeO3 was 57.4 mg/kg in this artificial soil test of E. fetida exposed to Na2SeO3 for 14 d. However, there was no significant differences when earthworms were exposed to different concentrations of Na2SeO3. The selected metabolic markers were ATP, lactic acid, leucine, alanine, valine, glycine, glutamic acid, lysine, α-glucose and betaine. Na2SeO3 affected the metabolic level of earthworms, as the percentage of metabolic markers in the earthworm changes when exposed to different concentrations of Na2SeO3. The metabolic disturbances were greater with increasing concentrations of Na2SeO3. The differential metabolic markers were significantly changed when exposed to Na2SeO3 comparing to those in the control group, affecting the tricarboxylic acid cycle process and breaking the metabolic balance. This study showed that Na2SeO3 had toxic effect on the growth and development of earthworms. In addition, this study provided a biochemical insights for the development of selenium-enriched agriculture.

Selenium oxyanion bioconcentration in natural freshwater periphyton

Selenium (Se) enrichment has been demonstrated to vary by several orders of magnitude among species of planktonic algae. This is a substantial source of uncertainty when modelling Se biodynamics in aquatic systems. In addition, Se bioconcentration data are largely lacking for periphytic species of algae, and for multi-species periphyton biofilms, adding to the challenge of modelling Se transfer in periphyton-based food webs. To better predict Se dynamics in periphyton dominated, freshwater ecosystems, the goal of this study was to assess the relative influence of periphyton community composition on the uptake of waterborne Se oxyanions. Naturally grown freshwater periphyton communities, sampled from five different water bodies, were exposed to environmentally relevant concentrations of selenite [Se(IV)] or selenate [Se(VI)] (nominal concentrations of 5 and 25 μg Se L−1) under similar, controlled laboratory conditions for a period of 8 days. Unique periphyton assemblages were derived from the five different field sites, as confirmed by light microscopy and targeted DNA sequencing of the plastid 23S rRNA gene in algae. Selenium accumulation demonstrated a maximum of 23.6-fold difference for Se(IV) enrichment and 2.1-fold difference for Se(VI) enrichment across the periphyton/biofilm assemblages tested. The assemblage from one field site demonstrated both high accumulation of Se(IV) and iron, and was subjected to additional experimentation to elucidate the mechanism(s) of Se accumulation. Selenite accumulation (at nominal concentrations of 5 and 25 μg Se L−1 and mean pH of 7.5 across all treatment replicates) was assessed in both unaltered and heat-killed periphyton, and in periphyton from the same site grown without light to exclude phototrophic organisms. Following an exposure length of 8 days, all periphyton treatments showed similar levels of Se accumulation, indicating that much of the apparent uptake of Se(IV) was due to non-biological processes (i.e., surface adsorption). The results of this study will help reduce uncertainty in the prediction of Se dynamics and food-chain transfer in freshwater environments. Further exploration of the ecological consequences of extracellular adsorption of Se(IV) to periphyton, rather than intracellular absorption, is recommended to further refine predictions related to Se biodynamics in freshwater food webs.

Selenium-enriched Coriolus versicolor mushroom biomass: potential novel food supplement with improved selenium bioavailability.

The ability of Coriolus versicolor medicinal mushroom to accumulate and transform selenium from selenourea and sodium selenite into an organic form-l-selenomethionine-during growth in liquid medium is examined in this paper. Additionally, the impact of supplementation on biological activity of the selenated mushroom methanol extracts, as well as their chemical composition, is studied. Selenium accumulation was more efficient with sodium selenite application, but biomass yield was significantly lower (1.89 g DW L-1 ) compared to samples enriched with selenourea (4.48 g DW L-1 ). Mushroom sample obtained after growing in liquid medium with selenourea had significantly higher l-selenomethionine content compared to the sample grown in medium with sodium selenite. Selenium-enriched methanol extracts of C. versicolor mushroom showed improved antimicrobial and antioxidant activities compared to non-enriched extract. Our results suggest that C. versicolor mushroom cultivated in liquid culture enriched with selenourea can be used for the production of novel food supplements with improved selenium bioavailability. More than 30% of total accumulated selenium from selenourea is transformed into l-selenomethionine. Differences in biological activity of methanol extracts can be explained not only by different selenium content but also by the differences in chemical composition of extracts. © 2019 Society of Chemical Industry.

The Biological Activity of a Selenium Nanocomposite Encapsulated in Carrageenan Macromolecules with Respect to Ring Rot Pathogenesis of Potato Plants

The effect of selenium nanocomposite encapsulated in a carrageenan matrix (NC Se/Car) on the Clavibacter michiganensis ssp. sepedonicus (Cms) bacteria (causing potato ring rot) and potato plants has been studied. The electron microscopy data indicate that NC Se/Car comprise spherical selenium nanoparticles (of a wide size range) forming aggregates. The nanocomposite has not been found to exhibit any bacteriostatic and antibiofilm activity against Cms. Our experiments on plants have shown a stimulating effect of NC Se/Car on the plant biometric indicators and a decreased harmful effect of Cms infection. The insignificant accumulation of selenium in the potato tissues treated with NC Se/Car (0.01–0.03% of air-dry weight) has been found. These results allow us to consider NC Se/Car as a plant development stimulator for agricultural crops.

Transcriptional profiling of Auricularia cornea in selenium accumulation

Auricularia cornea is a widely cultivated edible fungus with substantial nutritive value. This study aimed to enrich the multifunctional bionutrient element selenium in A. cornea to improve its quality and explore the accumulation of selenium in the fungus using high-throughput RNA-Seq technology. In general, the treatment group with a 100 µg/g supply of selenium outperformed the other treatment groups in terms of high yield, rich crude polysaccharides and a high total selenium concentration. Additional evidences demonstrated the budding and mature phases were two typical growth stages of A. cornea and were important for the accumulation of selenium. Therefore, the budding and mature phase tissues of A. cornea in the treatment group with a 100 µg/g supply of selenium were used for transcriptome analysis and compared to those of a control group that lacked additional selenium. A total of 2.56 × 105 unigenes from A. cornea transcriptome were assembled and annotated to five frequently used databases including NR, GO, KEGG, eggNOG and SwissProt. GO and KEGG pathway analysis revealed that genes involved in metabolic process and translation were up-expressed at the budding stage in response to selenium supplementation, including amino acid metabolism, lipid metabolism, ribosome. In addition, the differential gene expression patterns of A. cornea suggested that the up-expressed genes were more likely to be detected at the budding stage than at the mature stage. These results provide insights into the transcriptional response of A. cornea to selenium accumulation.

Arsenic and selenium in shore soils and bottom sediments of Samara city ponds

Arsenic and selenium are included in the group of chemical elements of the first hazard class, which confirms the need to analyze their content in natural environments of natural and man-made ecosystems during ecological and biogeochemical monitoring. By their chemical properties, arsenic and selenium are metalloids or semimetals. In very low concentrations, they are necessary for the normal functioning of the organisms, but with increasing concentrations in the habitat or food they show high toxicity. Particularly dangerous is the accumulation of arsenic and selenium in accumulative environments and landscapes, which include soils and confined water bodies. For the urban ecosystems of the Samara Region, earlier monitoring of the content of arsenic and selenium in the components of their accumulative landscapes was not carried out, which confirms the relevance and practical significance of the presented materials. The authors carried out ecological and geochemical studies of the accumulation of arsenic and selenium in coastal soils and bottom sediments of twenty ponds located in the Samara city within the coastal slope of the Saratov reservoir (Volga slope) and on the watershed between the Saratov reservoir and the Samara River. The results analysis showed a relatively low level of arsenic accumulation in the analyzed substrates of the studied ponds. Compared with the level of regional background for the Middle Volga, the studied accumulative aqual landscapes are noticeably enriched in selenium (2-15 times). The technogenic influx of arsenic and selenium into the accumulative landscapes of the Samara city may be associated with the activities of metalworking and machine-building enterprises, as well as thermal power plants. The materials presented in the paper concerning the content of arsenic and selenium in coastal soils and bottom sediments of urban ponds in the Samara city can be considered as pioneering for the region and subsequently used in the ecological and geochemical monitoring of regional urban ecosystems.

HYGIENIC ASSESSMENT OF THE SECURITY WITH SELENIUM IN VARIOUS GROUPS OF THE POPULATION OF THE ORENBURG REGION

The integrated approach to studying of the element status of the population as a whole, is an actual problem in biology and medicine. 1270 people took part in research - children, teenagers and adults. Selenium definition in hair was carried out on the basis of test laboratory Autonomous Non-Commercial Organization Center of Biotic Medicine, according to methodical instructions TORMENTS 4.1.1482-03, 4.1.1483-03. Average values of selenium in hair (25 - 75 testily interval), received when carrying out population researches in various regions of Russia became a basis for an assessment of accumulation of selenium in hair surveyed. These testily intervals were accepted by us, according to A.V. Skalnu (2003) recommendations, as reference sizes for persons of the corresponding age. These concentration of selenium received during research in hair of the children’s population were much lower than reference sizes: at boys this indicator was lowered by 1,3 times, and at girls by 1,5 times of rather minimum level of physiologically admissible sizes for persons of the corresponding age. The similar picture developed and in group of the surveyed teenagers. Four multiple decrease in indicators of concentration of selenium in hair of both groups of teenagers concerning level 25 testily was established. The comparative analysis of concentration of selenium in hair of adult population of the Orenburg region established decrease in concentration of selenium in hair in all surveyed on the average by 1,5 times of rather reference sizes. The hygienic assessment of concentration of selenium in hair of all surveyed persons revealed decrease in concentration of selenium in hair rather physiologically admissible sizes for all surveyed age groups of the population of the Orenburg region.

Effect of dietary Bio-fermented selenium on growth performance, nonspecific immune enzyme, proximate composition and bioaccumulation of zebrafish (Danio rerio)

A four-weeks feeding trial was conducted to evaluate the effects of dietary Bio-fermented selenium (Bio-Se) on zebrafish (Danio rerio). Effects of three Se diets containing basal diet (1.63 mg Se/kg), L-Se diet (3 mg Se/kg), and H-Se diet (10 mg Se/kg) on growth performance, nonspecific immune enzyme activities, proximate composition, and selenium accumulation of zebrafish were tested. The results indicate that body weight gain (BWG), specific growth rate (SGR), and nonspecific immune enzyme [glutathione peroxidase (GPx), superoxide dismutase (SOD), and alkaline phosphatase (ALP)] activities of fish fed with L-Se diet were significantly highest among all the groups. However, increased H2O2 content and decreased SOD activity indicates oxidative stress when fish was fed with H-Se diet. Dietary Se did not affect the proximate composition of zebrafish. The Se concentration in muscle increased in a dose-dependent manner, and the highest Se concentration was recorded in H-Se diet. In summary, the growth performance and nonspecific immunity of zebrafish fed with L-Se diet improved, but exposure to higher concentrations of Bio-Se severely affects the health status of fish.

Effects of foliar application of selenate and selenite at different growth stages on Selenium accumulation and speciation in potato (Solanum tuberosum L.)

Since the potato is a new staple food in China, the production of selenium (Se)-enriched potato may be an effective approach for Se supplementation in Se-deficient populations. Herein, we biofortified potato via the foliar application of sodium selenate and sodium selenite at three growth stages and investigated the resulting Se contents and speciation. Results showed that selenate was more efficient than selenite in improving total Se, and the highest tuber Se concentration was obtained at the tuber bulking stage. However, the accumulation of inorganic Se was higher in tubers treated with selenate (31.9% of total Se) compared with the selenite treatment (1.5%). The major Se species in tubers treated with both selenite and selenate was selenomethionine, which accounted for ∼80.0% and ∼50.0% of total Se, respectively. The findings suggest that the foliar application of selenite during the tuber bulking stage is appropriate for the production of Se-rich potatoes.

Selenium Distribution and Translocation in Rice (Oryza sativa L.) under Different Naturally Seleniferous Soils

Selenium (Se) accumulation in plant foods may be providing dietary Se to minimize the health problems related to Se deficiency. In this study, rice plants were cultivated in different naturally seleniferous soils (0.5–1.5 mg Se kg−1). Se concentration in rice plant tissues was analysed, and the distribution and translocation of Se in rice were also studied. The effect of exogenous Se on yield and Se concentration in rice grain was also investigated by spraying Na2SeO3 (15 mg L−1, 15 g ha−1). Results show that Se concentration in root, straw and grain of rice was increased with increased concentrations of Se in seleniferous soils. The root accumulated higher Se than straw and grain under the same naturally seleniferous soil. Spraying Se significantly increased Se concentration in grain, hull, brown rice and polished rice compared with spraying water. Se concentration in the grain fractions was in the following order: Bran > brown rice > whole grain > polished rice > hull. About 13.7% Se in wholegrain was discarded by milling process if about 6.9% of it was polished as bran. Se-enriched rice could be produced in naturally seleniferous soils with Se concentration from 0.5 to 1.0 mg kg−1, and this polished rice would provide enough Se (60–80 μg day−1) to satisfy the human requirement. Therefore, naturally seleniferous soils may be an effective way to produce Se-enriched rice without spraying Se fertilizer, which will be more economically feasible and environmentally friendly for without exogenous Se added to the soils or plants. However, the polished rice and brown rice, produced by spraying Na2SeO3 (15 g ha−1) or grown in soil with total Se upto 1.5 mg kg−1 was not suitable for daily human consumption, unless diluted with Se-deficient rice to meet the standard (≤0.3 mg Se kg−1). This study imparted a better understanding of the utilization of seleniferous soils and Se-enriched rice for human health and food safety.

Characterization of selenium accumulation of different rice genotypes in Chinese natural seleniferous soil

In this study, the difference of Se content in brown rice of different rice genotypes was evaluated on natural seleniferous soil. Firstly, the Se content of brown rice in 80 rice germplasm resources was determined, which ranged from 0.0249–0.1426 mg/kg, showing obvious differences. Next, two cultivars with a significant difference in Se content in brown rice, i.e., cv. Wuyangeng (high) and cv. IR68144 (low), were used to study the distribution pattern of Se in different organs. Moreover, the physiological mechanism of the Se content diversity in brown rice of the two cultivars was explored preliminarily. The results showed that the Se content of cv. Wuyangeng was 2–3 times higher compared to cv. IR68144. However, the Se contents of cv. IR68144 root and leaf were significantly higher than that of cv. Wuyangeng under both natural soil environment and artificial nutrient solution culture. Cv. IR68144 also had a stronger root Se accumulation coefficient and shoot Se transfer coefficient. Consequently, it can be inferred that the stronger Se transfer ability from stem to grain was the key reason for the higher Se content in brown rice cv. Wuyangeng than in cv. IR68144.

Effects of dietary selenium polysaccharide on growth performance, oxidative stress and tissue selenium accumulation of juvenile black sea bream, Acanthopagrus schlegelii

Selenium (Se) plays an important role in the immune system and is essential for growth. An 8-week growth trial was conducted to determine the dietary Se requirement of juvenile black sea bream, Acanthopagrus schlegelii. A basal diet was supplemented with Se polysaccharide at levels of 0.34, 0.52, 0.68, 0.91, 1.08 and 3.06 mg Se/kg. Triplicates of black sea bream (13.00 ± 0.20 g) were each hand fed one of the diets. Abnormal fish behavior was not observed, and mortality was not influenced by dietary treatment. Increased levels of Se significantly increased the weight gain in fish fed ≤0.91 mg Se/kg diets, while higher inclusion levels showed a slightly decreasing trend for growth performance. The activities of superoxide dismutase, glutathione peroxidase, catalase and glutathione reductase in the serum and liver significantly increased and levelled off in the fish fed ≥1.08 mg Se/kg diets, while the liver and serum malonaldehyde contents significantly decreased with increasing Se levels. The liver and muscle Se contents linearly increased with increasing dietary Se levels. On the basis of the obtained results, it can be concluded that the dietary Se requirement for juvenile black sea bream appears to be 0.86 mg/kg based on weight gain.

Accumulation, mobilization, and transformation of selenium in rice grain provided with foliar sodium selenite.

Selenium is an indispensable trace element for humans and its deficiency can lead to serious health complications. Nearly 70% of the area of China faces selenium deficiency. To deal with this problem, selenium-enriched rice has been increasingly incorporated into everyday diets. However, there is a lack of in-depth studies of the absorption, translocation, and transformation of selenium in the different parts of the rice plant when sprayed with sodium selenite. Foliar sodium selenite applied at critical growth stages can significantly improve the total and organic selenium content of plants. Application of 10 mg L-1 sodium selenite led to the most organic selenium (0.03 mg kg-1 ) in polished rice. Correlation studies of sodium selenite applied to leaves and other plant parts showed that total selenium accumulated most in glume, followed by rice bran, then polished rice, and finally embryo. The behavior of organic selenium was different. Organic selenium accumulated most in polished rice, then embryo, then rice bran, and finally glume. Moreover, 75-85% of the Se found in polished rice and embryo was organic in nature. We propose that 10 mg L-1 sodium selenite can be recommended as appropriate for foliar fertilization in the organic selenium biofortification of Se-free rice. © 2018 Society of Chemical Industry.

Study on selenium accumulation characteristics of different ploidies Solanum nigrum

The selenium accumulation characteristics of Solanum nigrum with different ploidy were studied by the pot experiment, and the biomass, selenium content and selenium accumulation of diploid (Solanum photeinocarpum), tetraploid (Solanum photeinocarpum) and hexaploid (Solanum nigrum) plants were determined, the results showed that there was a difference between the biomass and selenium content of three kinds of ploidy plants of S. nigrum. The biomass of various organs and shoots of hexaploid S. nigrum plants was significantly higher than that of tetraploid and diploid plants. In terms of selenium content and selenium accumulation, the hexaploid plants had the highest selenium content and selenium accumulation in stems, leaves and shoots. After comprehensive comparison, the hexaploid S. nigrum has large biomass and strong selenium-enriching ability, so it can be used as an excellent plant material for soil selenium absorption and transformation.

Study on the selenium accumulation of peach seedlings

An experiment was conducted to study the effect of peach seedlings (Prunus davidiana) grown in nutrient solution with different selenium concentration. The results showed that selenium concentration were 0.05 and 0.10 mg/L which caused a marked increase of roots and shoorts biomass, and the root/shoot ratio were relatively low (0.180 and 0.170) compared with control, and other selenium treatments decreased significantly the biomass. Consequently, 0.05 and 0.10 mg/L selenium treatments were conducive to peach seedlings growth, while the peach seedlings was inhibited significantly by the increasing concentration of selenium (≥ 0.10 mg/L). Selenium content of peach seedlings increased remarkably with the increase of selenium concentration that indicated the accumulation of selenium in peach seedlings had a linear relation with the dose of selenium. Above all, when selenium concentration in the range of 0-0.10 mg/ L, which not only promotes peach seedlings growth, but also increases peach seedlings selenium content.

不同甘薯品种在安康地区的适应性及对硒元素吸收积累的研究

不同甘薯品种在安康地区的适应性及对硒元素吸收积累的研究

Influences of dietary selenomethionine exposure on tissue accumulation, blood biochemical profiles, gene expression and intestinal microbiota of Carassius auratus

A 30-days feeding trail was conducted to determine the sensitivity of Carassius auratus to the toxicological effects of elevated dietary Selenomethionine (Se-Met). C. auratus averaging 23.56 ± 1.82 g were exposed to four Se-Met concentrations (mg Se/kg): 0 (Se-Met0), 5 (Se-Met5), 10 (Se-Met10) and 20 (Se-Met20) to estimate the effects on tissue selenium (Se) accumulation, blood biochemical profiles, transcript expression and intestinal microbiota. Se accumulated in the kidney, liver and muscle in a dose-dependent manner and followed this order: kidney > liver > muscle, the highest accumulation were obtained in kidney of Se-Met20 diet after 30 days of feeding. Serum contents of alanine transaminase (ALT), aspartate transaminase (AST) and alkaline phosphatase (ALP) in fish exposed to Se-Met20 group was significantly highest among Se-Met exposure groups. Hydrogen peroxide (H2O2) concentrations in liver were affected by dietary Se-Met exposures. Liver contents of total antioxidant capacity (TAC), catalase (CAT), glutathione peroxidase (GPx) and malondialdehyde (MDA) in fish exposure to Se-Met5 group was significantly highest among Se-Met exposure groups. Growth hormone receptor (GHR), insulin-like growth factor 1 (IGF-1) and antioxidant enzyme related genes including glutathione peroxidase (GPx), catalase (CAT) and glutathione S-transferase (GST) expression in liver were down-regulated with the concentration of Se-Met exposure groups. The results of high-throughput sequencing showed that gut microbial communities and hierarchy cluster heatmap analysis were significantly affected by Se-Met exposure. The abundances of Cetobacterium and Vibrio increased while fish exposed to Se-Met20 group. The abundance of Ralstonia increased when the Se-Met exposure dose reached 10 mg Se kg−1. The results suggested that the exposure to elevated dietary Se-Met may result toxic effects in C. auratus.

Study on Selenium Accumulation Characteristics of Radish

In order to study the effects of different concentrations of selenium on the selenium accumulation characteristics of radish, we used the pot experiment to study effects of different selenium concentrations (0, 5, 10, 25, 50, 75, and 100 mg/kg) on the biomass and selenium content of radish. The results showed that selenium stress inhibited the biomass of radish and the higher the concentration of selenium and the stronger the inhibition of radish growth. In addition, the selenium content of radish increased with the increase of selenium concentration. Selenium content in radish roots, tubers and leaves were in the ranges of 21.71-346.64 mg/kg, 11.05-251.38 mg/kg, and 8.34-210.91 mg/kg respectively under the selenium stress. Compared with the selenium concentration of 0 mg/kg, all treatments significantly increased the tubers, leaves, shoots and whole plants of radish selenium accumulation. In all treatments, when the concentration of selenium was 25 mg/kg, the selenium accumulation of each part of radish reached the maximum and the selenium accumulation of radish in shoots and whole plants reached 111.96 μg/plant and 119.21 μg/plant respectively. In a word, radish has the strongest accumulation ability of selenium in soil when the concentration of selenium is 25 mg/kg, which can be considered as the best selenium concentration to increase the selenium content of radish.

Selenium Accumulation Characteristics of Solanum alatum

To study the effects of different concentrations of selenium on the selenium accumulation characteristics of Solanum alatum, we used the pot experiment to study effects of different selenium concentrations (0, 5, 10, 25, 50, 75, 100 mg/kg) on the biomass and selenium content of S. alatum. The results showed that all concentrations of selenium reduced the biomass of S. alatum. The biomass of S. alatum decreased with the increase of selenium concentration. In addition, with the increase of Se concentration, the Se content of S. alatum roots and stems increased. The Se content of S. alatum leaves and shoots increased first and then decreased with the increase of Se concentration. The selenium accumulation of each part of S. alatum increased first and then decreased with the increase of selenium concentration. Selenium accumulation in S. alaum shoots and whole plants were in the ranges of 0.503-13.915 μg/plant and 1.089-18.319 μg/plant respectively under the selenium stress. In all treatments, when the concentration of selenium was 10 mg/kg, the selenium accumulation of each part of S. alatum was the highest. Therefore S. alatum is most suitable for planting at a selenium concentration of 10 mg/kg.

Study on Selenium Accumulation Characteristics of Pterocypsela laciniata

Pot experiments were conducted to investigate the selenium accumulation characteristics of Pterocypsela laciniata under different selenium concentrations. The results showed that with the increase of Se concentration in soil, the biomass of root, stem, leaf and shoot of P. laciniata decreased, but the Se content of root, stem, leaf and aboveground part increased, and all reached the maximum when Se concentration was 100 mg/kg. When the concentration of Se in soil was 5 mg/kg and 10 mg/kg, the root and shoot of P. laciniata had the strongest ability to enrich Se in soil, respectively. When the concentration of selenium was 10 mg/kg, the accumulation of selenium in root and shoot of P. laciniata reached 123.06 μg/plant and 67.63 μg/plant respectively. Therefore, P. laciniata has strong selenium accumulation ability.