Effects of selenium application concentration, period and method on the selenium content and grain yield of Tartary buckwheat of different varieties.

BACKGROUND: As a potential selenium-enriched crop, it is of great significance to study the selenium application of Tartary buckwheat. Therefore, to study the effects of selenium application concentration, variety, selenium application period and method on the grain selenium content and yield of Tartary buckwheat, an orthogonal experimental design was used to carry out field experiments in the Jinzhong and Northwest Shanxi ecological regions at the same time. Heifeng 1 and Jinqiao 2 were applied at the branching stage and flowering stage in the Jinzhong, and Heifeng 1 and Jinqiao 6 were applied at the early flowering stage and peak flowering stage in the Northwest Shanxi with different concentrations of sodium selenite (0, 1.37, 2.74, 5.48, 8.22, 12.33, 18.495, 27.7425 g hm-2 ) by foliar spraying and soil application. RESULTS: The results showed that the selenium content in Tartary buckwheat grains was positively correlated with the selenium application concentration and increased with increasing selenium application concentration, while the yield of Tartary buckwheat first increased and then decreased with the selenium application concentration. The grain selenium content and yield of Tartary buckwheat were affected by the selenium application concentration, variety and application method. CONCLUSION: The most effective selenium biofortification program was spraying 2.32 g hm-2 sodium selenite on the leaves of Heifeng 1 at the early flowering stage in the Jinzhong. In the Northwest Shanxi, spraying 11.01 g hm-2 sodium selenite on the leaves of Jinqiao 6 at the flowering stage was the most effective selenium biofortification program. © 2022 Society of Chemical Industry.

Selenium modulated gut flora and promoted decomposition of methylmercury in methylmercury-poisoned rats.

INTRODUCTION: Selenium plays important roles in antagonizing the toxicity of methylmercury. The underlying mechanism for the antagonism between Se and MeHg is still not fully understood. OBJECTIVE: The role of gut flora against the toxicity of environmental contaminants is receiving more and more attention. The objective of this study was to investigate the role of Se against MeHg-poisoning in the modulation of gut flora and the decomposition of MeHg. METHODS: MeHg-poisoned rats were treated with sodium selenite every other day for 90 days. Fecal samples were collected on Day 8, 30, 60 and 90. Gut flora in feces was determined using 16S rRNA gene profiling, and the concentrations of Se and total mercury (THg) were measured by ICP-MS, and the concentration of MeHg was measured by CVAFS. RESULTS: Gut flora at both the ranks of phylum and genus in the MeHg-poisoned rats after Se treatment was modulated towards that in the control group, suggesting the restoration of the profile of gut flora. Increased THg was found in fecal samples after Se treatment on day 30. The percentage of MeHg (of total mercury) in the MeHg-poisoned group was in the range of 81-105% while it was 65-84% in the Se treatment group on different days, suggesting the increased decomposition of MeHg in MeHg-poisoned rats after Se treatment. CONCLUSIONS: This study suggests that MeHg poisoning damaged the abundance of gut flora and decreased their capacity for the decomposition of MeHg. After Se treatment, the abundance of gut flora was partially restored and the decomposition and excretion of MeHg was enhanced. These findings suggest that the modulation of gut flora may be one way to promote the health status in MeHg-poisoned rats and possibly in human beings.

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

BACKGROUND: 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. RESULTS: 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. CONCLUSIONS: 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.

Assessment of selenium bioaccumulation in lactic acid bacteria.

Selenium is an essential micronutrient for living beings, as it helps to maintain the normal physiological functions of the organism. The numerous discoveries involving the importance of this element to the health of human beings have fostered interest in research to develop enriched and functional foods. The present study evaluated the potential for bacterial strains of Enterococcus faecalis (CH121 and CH124), Lactobacillus parabuchneri (ML4), Lactobacillus paracasei (ML13, ML33, CH135, and CH139), and Lactobacillus plantarum (CH131) to bioaccumulate Se in their biomass by adding different concentrations of sodium selenite (30 to 200 mg/L) to the culture medium. Quantification of Se with UV and visible molecular absorption spectroscopy showed that the investigated bacteria were able to bioaccumulate this micromineral into their biomass. Two of the L. paracasei strains (ML13 and CH135) bioaccumulated the highest Se concentrations (38.1 ± 1.7 mg/g and 40.7 ± 1.1 mg/g, respectively) after culture in the presence of 150 mg/L of Se. This bioaccumulation potential has applications in the development of dairy products and may be an alternative Se source in the diets of humans and other animals.

Selective fluorescence detection method for selenide and selenol using monochlorobimane.

The low redox potential of selenide and selenol is physiologically important, as it confers efficient catalytic abilities to selenoproteins. Quantitative determination of selenol and selenide provide important clues for understanding the metabolism and physiological function of selenium. However, selective detection of selenol and selenide is extremely difficult because of their chemical similarity to thiol and sulfide. In this study, we established a highly sensitive, selective, quantitative, and simple method for detection of selenol and selenide, using a reaction with monochlorobimane (MCB), followed by ethyl acetate extraction of the product syn-(methyl,methyl)bimane. We analyzed selenide production from selenite, catalyzed by human glutathione reductase, and also determined selenide and selenol concentrations in Hepa1-6 cells using the MCB method, to demonstrate its practical applications. This study provides a new tool for selenium detection in biology.

Online preconcentration-IC-ICP-MS for selenium quantification and speciation at ultratraces.

Selenium (Se) is of key importance to human health with a very narrow concentration range of optimal dietary intake. Due to the inherent analytical challenge linked with the low natural abundance, information on precise and accurate Se speciation in deficient environments is hardly existent. This study presents a novel approach to determine Se species-specifically at ultratraces, by online coupling of a preconcentration (trap) column to an ion chromatography inductively coupled plasma mass spectrometry (IC-ICP-MS) system. It is demonstrated that with this robust and work/time efficient method, the predominant selenium oxyanions, selenite (Se(IV)) and selenate (Se(VI)), can be quantified down to 7.3 and 8.3 picogram total Se, respectively, in an overall analytical time of 420 s, only. The applicability for environmental samples was proven on pristine volcanic ashes collected from seven different volcanoes. The high sensitivity of the novel approach allowed to determine speciation in samples that were strongly depleted in total selenium (<0.05 mg kg(-1) Se) with only minor fractions of Se mobilized (i.e., less than 10% of the total selenium was leached in 10 out of 12 samples). The studied samples showed considerate differences in selenium speciation, with selenite and selenate co-occurring in most samples. The fact that the studied sample leachates had a wide range of pH (3.78-9.55) and major anion/cation composition underlines the versatility and wide potential application range of the method presented.

Biomimetic chromatographic analysis of selenium species: application for the estimation of their pharmacokinetic properties.

The retention behavior of selenites, selenates, seleno-DL-methionine, selenocystine, selenocystamine, selenourea, dimethyl selenide, and dimethyl diselenide was investigated by means of biomimetic liquid chromatography. For this purpose, two immobilized artificial membrane (IAM) columns, namely, IAM.PC.DD2 and IAM.PC.MG, and two immobilized plasma protein columns, human serum albumin (HSA) and alpha(1)-acid glycoprotein (AGP) columns, were employed using different mobile phase conditions in respect to pH and buffer composition. In general, satisfactory interrelations between retention factors obtained with the two IAM stationary phases and HSA/AGP columns were obtained. Large differences were observed between biomimetic retention factors and octanol-water logD values, since the latter fail to describe electrostatic interactions. In contrast, despite the column diversity, the net retention outcome on all four biomimetic columns was quite similar, especially in the presence of phosphate-buffered saline, which by its effective shielding alleviates the differences between the stationary phases. Of the two IAM columns, IAM.PC.DD2 showed better performance when compared with HSA and AGP columns as well as to octanol-water partitioning. Biomimetic chromatographic indices were further used to estimate the percentage of human oral absorption and plasma protein binding of the eight selenium species investigated, according to equations previously reported in the literature. The estimated values of human oral absorption imply moderate absorption only for dimethyl diselenide, which also may exhibit considerable plasma protein binding. Moderate affinity for plasma proteins should also be expected for dimethyl selenide and selenocystamine.

Effects of Different Selenium Sources on Laying Performance, Egg Selenium Concentration, and Antioxidant Capacity in Laying Hens.

Supplementation of selenium (Se) is a common practice in the poultry industry via sodium selenite (SS) and selenium yeast (SY), while the effects of nano-selenium (NS) on laying hens are poorly known. This study aimed to compare the effects of NS, SS, and SY on productivity; selenium (Se) deposition in eggs; and antioxidant capacity in laying hens. A total of 288 30-week-old Brown Hy-line laying hens were randomly assigned into four dietary treatments, which included corn-soybean meal basal diet (Con) without Se sources and basal diets supplemented with 0.3 mg Se/kg as SS, SY, or NS, respectively. The results exhibited that Se-supplemented treatments achieved greater egg production, egg weight, and daily egg mass, also better feed conversion ratio than Con group (p < 0.05). Se supplementation significant increased egg Se concentration and decreased the egg Se deposition efficiency (p < 0.05), while SY or NS supplementation had higher Se deposition efficiency than SS group at 35 days (p < 0.05). Moreover, serum glutathione peroxidase (GSH-Px) activity increased in SS or NS group compared to Con group (p < 0.05). The glutathione peroxidase 4 (GPX-4) mRNA levels in liver were significantly higher (p < 0.05) in SS or SY group than in NS group, and mRNA levels of the methionine (Met) metabolism gene glycine N-methyltranserfase (GNMT) were markedly upregulated (p < 0.05) in SY group compared to SS or NS group. Taken together, the results revealed Se from SY is deposited into eggs more efficiently than Se from NS or SS, probably via enhancing the route of Met metabolism. Meanwhile, it might be concluded that SS or SY supplementation directly regulated GSH-Px activity via enhancing GPx4 level, whereas NS via GPx1, thus affecting body oxidation and development.

Effects of sodium selenite and L-selenomethionine on feed intake, clinically relevant blood parameters and selenium species in plasma, colostrum and milk from high-yielding sows.

A field study in periparturient sows fed different dietary concentrations of either sodium selenite or L-selenomethionine (SeMet) was conducted to evaluate feed intake, haematological and biochemical parameters as well as to describe some key selenium (Se) species, namely selenoprotein P (SelP), selenoalbumin (SeAlb) and selenomethionine (SeMet) as well as total Se in plasma, colostrum and milk. Thirty-two sows were allotted to four treatments from 30 days (d) prepartum throughout on average a 32 d lactation period. Sodium selenite supplemented diets contained 0.40 and 0.60 mg Se/kg feed, while SeMet supplemented feed contained 0.26 and 0.43 mg Se/kg feed. Concentrations of sodium selenite and SeMet in complete feed exceeded the upper limits for total dietary Se and added organic Se, respectively, according to the European Union legislation. Blood samples were collected at initiation of the study, at farrowing and at weaning. Colostrum samples were collected at farrowing and milk samples at weaning. Se species were subjected to liquid chromatography, and total Se and Se species were determined using inductively coupled plasma mass spectrometry. The SeMet supplemented diets resulted in higher feed intake and in higher levels of total Se, SelP, SeAlb and SeMet in colostrum compared with sows fed sodium selenite. Similar results were obtained for levels of total Se and SeMet in milk at weaning. The higher dietary sodium selenite concentration in sows' feed did not increase the Se transfer into colostrum or milk when compared with those receiving the lower level of sodium selenite. However, the increase in serum-Zn from initiation until farrowing, observed in sows fed SeMet as well as the higher glutamate dehydrogenase activity in sodium selenite supplemented sows in this period might indicate a higher requirement of antioxidant defence in sodium selenite-supplemented sows. To our knowledge, the present data on Se species in plasma, colostrum and milk of sows represent the most complete investigation of Se in sows conducted to date. A higher amount of the above-mentioned Se species in the colostrum of sows supplemented with SeMet might strengthen the piglets' antioxidative system and passive immunity as well as improve their average daily weight gain. The higher feed intake in sows fed diets supplemented with SeMet is an interesting finding that warrants further investigation.

Zea mays L. Grain: Increase in Nutraceutical and Antioxidant Properties Due to Se Fortification in Low and High Water Regimes.

This work aimed to investigate the effect of selenium (Se) and irrigation on the grain yield, on the forms of Se, phenols, and carotenes, and on some antioxidant activities of maize ( Zea mays L.) grains. To reach this goal, a 2 year experiment was undertaken. Maize was fertigated with sodium selenite at the rate of 200 g of Se ha-1 and grown under two water regimes. While the irrigation did not show a clear effect on the selected parameters, Se fertigation increased the contents of inorganic and organic Se forms, xanthophyll, and salicylic acid. Furthermore, while Se fertigation decreased the hydroxycinnamic acid content, generally higher antioxidant activities were found in Se-treated grains than in the control. These findings suggest that Se fertigation increases most of the nutraceutical values of maize grains, which therefore might improve human and livestock health and could increase the maize grain shelf life and its byproducts.

Determination of selenium and tellurium compounds in biological samples by ion chromatography dynamic reaction cell inductively coupled plasma mass spectrometry.

An ion chromatography-inductively coupled plasma mass spectrometric (IC-ICP-MS) method for the speciation of selenium and tellurium compounds namely selenite [Se(IV)], selenate [Se(VI)], Se-methylselenocysteine (MeSeCys), selenomethione (SeMet), tellurite [Te(IV)] and tellurate [Te(VI)] is described. Chromatographic separation is performed in gradient elution mode using 0.5 mmol L(-1) ammonium citrate in 2% methanol (pH 3.7) and 20 mmol L(-1) ammonium citrate in 2% methanol (pH 8.0). The analyses are carried out using dynamic reaction cell (DRC) ICP-MS. The DRC conditions have also been optimized to obtain interference free measurements of (78)Se(+) and (80)Se(+) which are otherwise interfered by (38)Ar(40)Ar(+) and (40)Ar(40)Ar(+), respectively. The detection limits of the procedure are in the range 0.01-0.03 ng Se mL(-1) and 0.01-0.08 ng Te mL(-1), respectively. The accuracy of the method has been verified by comparing the sum of the concentrations of individual species obtained by the present procedure with the total concentration of the elements in two NIST SRMs Whole Milk Powder RM 8435 and Rice Flour SRM 1568a. The selenium and tellurium species are extracted from milk powder and rice flour samples by using Protease XIV at 70 degrees C on a water bath for 30 min.

Capabilities of microbore columns coupled to inductively coupled plasma mass spectrometry in speciation of arsenic and selenium.

The performance of microHPLC-microconcentric nebulizer-inductively coupled plasma-mass spectrometry (ICP-MS) coupling for the simultaneous determination of As(III), As(V), monomethylarsenic acid (MMA), dimethylarsinic acid (DMA), selenite (SeIV) and selenate (SeVI) in water was evaluated. The accurate reduction of the off-column dead volume, specially the capillary of the micronebulizer, as well as the optimization of chromatographic conditions led to the claimed advantages expected for microbore columns: a significant diminution of sample and solvent consumption without sacrificing sensitivity and the overall resolution in faster analysis time (less than 5 min). Detection limits are in the range 0.03-0.04 microg L(-1) for arsenic species and 0.35 microg L(-1) for selenium species. The developed method was validated by analysing different spiked environmental water samples. Linearity, tested up to 50 microg L(-1), showed correlation coefficients above 0.999 and no matrix effect for high saline water samples. Good accuracy and repeatability was obtained for spiked influent and effluent water treatment plant.

Selenium Supplementation Changes the Ion Profile in the Pancreas of Chickens Treated with Cadmium.

Increasing evidence indicates that selenium (Se) could antagonize metal toxicity, including cadmium (Cd) toxicity. However, the effects of Se on Cd-induced changes in the ion profile in the pancreas of chickens have not been reported. In the present study, 128 Hy-Line brown laying chickens were divided into the control group, Se-treated group, Se/Cd-treated group, and Cd-treated group, and we detected the concentrations of 28 ions in the four groups by inductively coupled plasma mass spectrometry. In the Cd-treated group, the accumulation of Cd in the pancreas was 836.8 times higher that than in the control group (27,353.71 ppb/32.69 ppb). Meanwhile, the Ca, Ti, Fe, Mo, Li, Al, and Pb levels increased and the Cr, Mn, Ni, Cu, Zn, Se, Sr, and Sb levels decreased due to sub-chronic Cd poisoning. The Fe, Mo, Ba, and Pb levels decreased in the Se/Cd-treated group. Our findings suggest that Cd can accumulate in the chicken pancreas and affect the ion profiles, whereas Se can ameliorate the accumulation of Cd and change the ion profiles in the chicken pancreas.

Effects of acute and subchronic exposures to waterborne selenite on the physiological stress response and oxidative stress indicators in juvenile rainbow trout.

Selenium (Se) is an essential element that may bioaccumulate to toxic levels. In fish, the major toxicity symptom is larval teratogenic deformities, but little is known about the effect of Se on other systems such as the physiological stress response and oxidative stress. To test the hypothesis that Se is a chemical stressor that causes toxicity through oxidative stress, juvenile rainbow trout were exposed to waterborne sodium selenite, and physiological stress response and stress-related parameters (plasma cortisol, glucose, T3 and T4, gill Na+/K+-ATPase, the ability of the head kidney to secrete cortisol, and condition factor) and hepatic oxidative stress indicators (reduced glutathione, glutathione peroxidase, and lipid peroxidation) were measured after 96 h (acute exposure to 0-2.67 mg/L Se) and 30 days (sub-chronic exposure to 0-0.16 mg/L). Acute exposure to waterborne sodium selenite significantly increased plasma cortisol levels (control=0.01+/-0.0 ng/mL, and 2.52 mg/L Se=73.5+/-22 ng/mL) and plasma glucose levels (control=0.75+/-0.1 mg/mL, and 3.60 mg/L Se=1.64+/-0.2 mg/mL), but gill Na+/K+-ATPase activities, plasma T3 and T4 levels, and condition factor were unchanged. The 96 h acute selenite exposure decreased hepatic reduced glutathione levels (control=18.4+/-1.5 micromol/mg protein, and 3.60 mg/L Se=12.4+/-1.1 micromol/mg protein). Lipid peroxidation levels (0.03-0.08 U/mg protein) and glutathione peroxidase (3.7-6.0 mU/mg protein) activities significantly varied with treatment. The 30 days sub-chronic exposure increased plasma cortisol, T3, and T4, but there was no effect on plasma glucose levels, gill Na+/K+-ATPase activity, the ability to secrete cortisol, and condition factor. The 30 days sub-chronic exposure to selenite did not alter antioxidant activities or lipid peroxidation levels. These experiments show, for the first time, that exposure to waterborne selenite up to 0.1mg/L, activates the physiological stress response in fish but does not impair cortisol secretion after 30 days. The decrease in reduced glutathione in juvenile rainbow trout subjected to the acute sodium selenite exposure suggests that oxidative stress may play an important role in the effects of Se in fish.

Chemical status of selenium in evaporation basins for disposal of agricultural drainage.

Evaporation basins (or ponds) are the most commonly used facilities for disposal of selenium-laden saline agricultural drainage in the closed hydrologic basin portion of the San Joaquin Valley, California. However concerns remain for potential risk from selenium (Se) toxicity to water fowl in these evaporation basins. In this study, we examined the chemical status of Se in both waters and sediments in two currently operating evaporation pond facilities in the Tulare Lake Drainage District. Some of the saline ponds have been colonized by brine-shrimp (Artemia), which have been harvested since 2001. We evaluated Se concentration and speciation, including selenate [Se(VI)], selenite [Se(IV)], and organic Se [org-Se or Se(-II)] in waters and sediment extracts, and fractionation (soluble, adsorbed, organic matter (OM)-associated, and Se(0) and other resistant forms) in sediments and organic-rich surface detrital layers from the decay of algal blooms. Selenium in ponds without vascular plants exhibited similar behavior to wetlands with vascular plant present, indicating that similar Se transformation processes and mechanisms had resulted in Se immobilization and an increase of reduced Se species [Se(IV), org-Se, and Se(0)] from Se(VI)-dominated input waters. Selenium concentrations in most pond waters were significantly lower than the influent drainage water. This decrease of dissolved Se concentration was accompanied by the increase of reduced Se species. Selenium accumulated preferentially in sediments of the initial pond cell receiving drainage water. Brine-shrimp harvesting activities did not affect Se speciation but may have reduced Se accumulation in surface detrital and sediments.

Selenium speciation by high-performance anion-exchange chromatography-post-column UV irradiation coupled with atomic fluorescence spectrometry.

A technique for the speciation of selenomethylcysteine (SeMeCys), selenocystine (SeCys), selenite [Se(IV)] and selenomethionine (SeMet) was established in this paper using high-performance anion-exchange chromatography coupled with atomic fluorescence spectrometry (HPAEC-AFS). Analytes were separated on an AminoPac PA10 column and then digested by on-line ultraviolet (UV) irradiation, which destroyed organic compound structure. Hydride generation was used as an available sample introduction technique for atomic fluorescence detection. The detection limits of four compounds were 1-5 microg/L (250 microL injection, 10 times of the baseline noise). The relative standard deviations (RSDs), calculated from seven consecutive injections of 100 microg/L standard mixtures, were from 2 to 4%. Selenious yeast tablet, which had been proposed as selenium supplement, and human urine collected from a volunteer were analyzed. Good spiked recoveries from 86 to 103% were obtained.

Kale carotenoids are unaffected by, whereas biomass production, elemental concentrations, and selenium accumulation respond to, changes in selenium fertility.

Selenium (Se) is a micronutrient in mammalian nutrition and is accumulated in kale (Brassica oleracea L. var. acephala), which has high levels of lutein and beta-carotene. Selenium, lutein, and beta-carotene have important human health benefits and possess strong antioxidant properties. The objectives of this study were to determine the influence of different Se [as sodium selenate (Na(2)SeO(4)) and sodium selenite (Na(2)SeO(3))] fertility levels on (1) biomass accumulation, (2) the accumulation patterns of carotenoid pigments, and (3) elemental accumulation in the leaves of kale. Winterbor kale was greenhouse-grown using nutrient solution culture with Se treatment concentrations of 0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, and 3.5 mg Se/L as Na(2)SeO(4) and 0.0, 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 mg Se/L as Na(2)SeO(3). Increases in either selenate (SeO(4)(-)(2)) or selenite (SeO(3)(-)(2)) resulted in decreases in kale leaf tissue biomass. Neither of the Se treatments had an effect on the accumulation of lutein or beta-carotene in leaf tissues. Increasing SeO(4)(-)(2) significantly increased the accumulation of kale leaf Se; however, leaf tissue Se did not significantly change over the SeO(3)(-)(2) treatments. Increases in SeO(4)(-)(2) affected the leaf tissue concentrations of P, K, Ca, Mg, S, B, Cu, Mn, and Mo, whereas SeO(3)(-)(2) only affected B and S. Growing kale in the presence of SeO(4)(-)(2) would result in the accumulation of high levels of tissue Se without affecting carotenoid concentrations.

Distribution coefficient of selenium in Japanese agricultural soils.

In order to evaluate the selenium (Se) sorption level in Japanese soils, soil/soil solution distribution coefficients (K(d)s) were obtained for 58 agricultural soil samples (seven soil classification groups) using 75Se as a tracer. Although several chemical forms of Se are present in agricultural fields, selenite was used, because it is the major inorganic Se form in acid soils such as found in Japan. The Kd values obtained covered a wide range, from 12 to 1060l/kg, and their arithmetic mean was 315l/kg. Among the soil groups, Andosols had higher Kd values. The Kd values for all samples were highly correlated with soil active-aluminum (Al) and active-iron (Fe) contents. Thus, active-Al and active-Fe were considered to be the major adsorbents of Se. Then, a new sequential extraction procedure was applied to 12 soil samples in order to quantify the effect of soil components on Se adsorption. The sequential extraction results showed that 80-100% of the adsorbed Se was recovered as Al-bound Se and Fe-bound Se. The amount of Al-bound Se was the highest in the soils that showed high Kd values, though the relative contribution of Fe-bound Se tended to increase with decreasing Kd values. The high values of Kd seemed to be caused mainly by the adsorption of Se onto active-Al in Japanese soils.

Composition of chemical species of selenium contained in selenium-enriched shiitake mushroom and vegetables determined by high performance liquid chromatography with inductively coupled plasma mass spectrometry.

Selenium (Se) species in Se-enriched shiitake mushroom (Lentinula edodes) were identified and quantified by high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICPMS). Two types of Se-enriched shiitake obtained from selenite- or selenate-fertilized mushroom beds were used. More than 80% of Se in both shiitake samples could not be extracted with 0.2 M HCl. Protease digestion released a large amount of selenomethionine from the shiitake enriched with selenite. However, most of the Se in the shiitake enriched with selenate was not released by protease but was released by a cell wall digestive enzyme and most of the Se released was identified as selenate. These results indicate that the main Se species in the shiitake enriched with selenite or selenate is selenomethionine bound to protein or selenate bound to polysaccharides in the cell wall, respectively. Several Se-enriched vegetables grown on a soil fertilized with selenate were also analyzed by HPLC-ICPMS. Four Se species, selenate, Se-methylselenocysteine, selenomethionine, gamma-glutamyl-Se-methylselenocysteine, and an unknown Se compound were detected in the vegetables. The composition of Se species varied with the kinds or parts of vegetables. The main Se species in bulbs, leaves or flowers of the Se-enriched garlic, onions, cabbage and ashitaba were selenate, Se-methylselenocysteine or gamma-glutamyl-Se-methylselenocysteine, while those in fruit bodies of the peppers and pumpkin were selenomethionine bound to protein. Bioavailabilities of Se in the shiitake mushroom enriched with selenite and the vegetables enriched with selenate are expected to be high, but that in shiitake enriched with selenate may be low.

Effect of supplementing selenium yeast in diets of laying hens on egg selenium content.

An 8-wk experiment was conducted using 90 Hy-Line W-98 hens (26 wk of age) to evaluate the use of organic Se from Se yeast as an Se source for laying hens. At 22 wk of age, the hens were placed on a low Se corn-soybean meal pretest diet for 4 wk. At the end of the pretest period, hens were placed on 1 of 3 experimental treatments; the low Se diet without supplementation (basal diet), basal diet with 0.3 ppm of Se added from sodium selenite, or basal diet with 0.3 ppm of Se added from Se yeast. Diets contained 0.11, 0.38, and 0.34 ppm Se for basal, basal plus sodium selenite, and basal plus Se yeast diets, respectively. The experimental diets were each fed to 10 replicate groups of 3 hens for 8 wk (26 to 34 wk of age). Selenium levels in eggs (mg/kg of whole egg) were analyzed at 0, 4, and 8 wk. Egg Se contents at 0 wk were similar among treatments. Eggs from hens fed the 2 Se-fortified diets had higher (P < 0.01) Se concentrations than did eggs from hens fed the low Se diet at 4 and 8 wk. The Se yeast diet also yielded levels of egg Se that were significantly higher (P < 0.01) than those from the sodium selenite diet at 4 and 8 wk. The Se yeast resulted in a 4.8-fold increase in egg Se concentration compared with a 2.8-fold increase for the sodium selenite diet over the unsupplemented diet at 8 wk (0.065, 0.182, and 0.311 ppm for the control, sodium selenite, and Se yeast diets, respectively). There were no differences in egg production, egg weight, feed intake, or mortality among treatments. Results of this study indicate that use of Se yeast in laying hens diets is very effective for increasing the Se content of eggs.