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Grains grown in various regions of the United States vary in their innate or natural Se contents. A regional study evaluated the effects of adding inorganic Se (sodium selenite) or organic Se (Se yeast) to diets with differing innate Se contents. A 2 × 2 + 1 factorial experiment evaluating 2 Se sources (organic or inorganic) at 2 Se levels (0.15 or 0.30 mg/kg) in 18 total replicates (n = 360 total pigs). A basal diet was fed without supplemental Se and served as the negative (basal) control. The study was conducted as a randomized complete block design in 9 states (Georgia, Illinois, Kentucky, Nebraska, North Carolina, Ohio, South Dakota, Texas, and Wisconsin) with each station conducting 2 replicates. Pigs were fed from 25 to approximately 115 kg BW. Similar dietary formulations were used at each station, incorporating a common source of trace mineral and Se premixes. Three pigs per treatment in 16 replicates (n = 240) were bled at 55, 85, and 115 kg BW and serum Se and glutathione peroxidase (GSH-Px) activities were determined. Three pigs (n = 260) from each treatment pen were killed at 115 kg BW and issues (liver, loin, and hair) were analyzed for Se. The corn Se content from the various states ranged from 0.026 to 0.283 mg Se/kg while the soybean meal Se content ranged from 0.086 to 0.798 mg Se/kg. Tissue and serum Se concentrations were greater (P < 0.01) when supplemental organic Se was fed, whereas serum GSH-Px was greater (P < 0.01) as Se level increased. There were linear increases (P < 0.01) in loin and quadratic increases (P < 0.01) in liver and hair Se concentrations as dietary Se level increased within each state. There was a source × level interaction (P < 0.01) for each tissue resulting in a greater increase when organic Se was fed. Serum Se and GSH-Px activity increased (P < 0.01) when both Se sources were fed and plateaued at each state at 0.15 mg Se/kg. There was a high and significant correlation between each tissue Se, serum Se, and GSH-Px activity to dietary Se level indicating that those states having greater grain natural Se contents also had greater tissue Se concentrations. These results indicate that a large difference in corn and soybean meal Se concentrations exists between states, that the addition of organic or inorganic Se to these grains increased tissue and serum Se in each state, and that organic Se was incorporated at greater concentrations in the loin, liver, and hair tissues of grower-finisher pigs than inorganic Se.

The aim of this study was to investigate the effects of dietary organic and inorganic selenium (Se) on the growth, Se concentration and meat quality of juvenile grouper, Epinephelus malabaricus. Organic Se (selenomethionine, SeMet) and inorganic Se (sodium selenite, Na2SeO3) were each added to the basal diet of juvenile grouper at 0.3, 0.7, 1.0 and 1.5 mg Se/kg-diet. The basal diet, without Se supplementation, was used as a control. There was a total of 9 experimental diets, and each was fed in triplicate to groups of fish (initial wt: 24.45 ± 0.73 g) in a seawater recirculating system for 8 weeks. Weight gain was significantly (P

Selenium (Se) is shown to be an essential element for poultry nutrition and a great deal of information has been accumulated for the last 20 years indicating that dietary form of Se is a major determinant of its efficiency. Generally speaking, there are two major Se sources for poultry, namely inorganic selenium (mainly selenite or selenate) and organic selenium in the form of selenomethionine (SeMet; mainly as Se-Yeast or SeMet preparations). In this review two main areas are considered in relation to the Se nutrition of breeders. Firstly, it is Se important roles in the maintenance of semen quality and optimal Se status of poultry males and Se is considered to be an important factor in ensuring the fertility of breeding stock. Secondly, Se status of the eggs from breeding birds is of great importance for the maintenance of the antioxidant system of the developing embryo. It is generally accepted that the hatching process is an oxidative stress and improvement in antioxidant defences of the embryo can increase hatchability. It is quite clear that the roles of Se in poultry nutrition and reproduction need new consideration in light of our recent knowledge on the molecular mechanisms of Se action at the cellular and sub-cellular levels. In particular, the discovery and characterisation of a range of new selenoproteins and a better understanding of the relationships between different antioxidants, as important parts of integrated antioxidant system with possibilities for antioxidant recycling in vivo, have yielded new insights in this area. In particular, it should be mentioned that increased levels of Se supplementation are not always beneficial, since selenoprotein synthesis is under the gene control and it reflects the need in these active molecules to deal with various stresses. However, to give a body a chance to affectively respond to environmental challenges by modulating selenoprotein synthesis there should be enough Se reserves available and this an ability of building Se reserves in the body is considered to be the main point in advantages of organic selenium in poultry and farm animal nutrition. A comprehensive analysis of the effects of various forms of dietary Se on its egg concentration, its transfer to the embryonic tissues and physiological consequences of the improved Se status of the progeny chicks are considered.

The aim of the study was to examine the assimilability of organic and inorganic selenium supplied as an additive to pig feed. The influence of both selenium forms on pig slaughter value as well as on the physicochemical and sensory characteristics of meat was also examined (experiment I). An attempt to establish the distribution of selenium in the body of experimental fatteners was made (experiment II). Experiment I was performed on 20 carcasses of crossbred pigs of (Polish Large White × Polish Landrace) × Duroc genotype and experiment II was carried out on 45 samples of longissimus and semimembranosus muscles taken from fatteners of the same genotype (PLW × PL × Duroc). The results obtained indicated that selenium supplementation in the diet had no impact on slaughter performance, meat quality and most physicochemical and sensory characteristics of meat. Selenium was found to have no significant effect on meat colour. The meat water holding capacity (WHC) was lower in the group of pigs fed organic selenium. The highest selenium concentration was found in the semimembranosus muscle of fatteners receiving the inorganic selenium additive.

The research results of impact «E-selenium» preparations to thyroid gland histophysiologies of soviet chinchilla breed females are represented. The regularity of growth and development of body parenchymal and stromal components as well as theirs correlation with thyroid and thyroid-stimulating hormones dynamics have been shown after selenium preparation injection.

Effect of selenium(+4) as selenite (Se32−) on two Azospirillum brasilense strains, which occupy different ecological niches (an epiphyte Sp7 and a facultative endophyte Sp245), was studied. The cultures grown in the medium with sodium selenite exhibited intense red coloration. Transmission electron microscopy and X-ray fluorescence analysis revealed accumulation of elementary selenium within the cells of both strains as nanoparticles 50–400 nm in diameter. The ability to reduce inorganic selenium(+4) to elementary selenium (as nanoparticles) has not been previously reported for azospirilla. Our results indicate the possibility to apply Azospirillum strains as microsymbionts for phytoremediation of, and cereal cultivation on, selenium-contaminated soils. The ability of azospirilla to synthesize selenium nanoparticles may be of interest for nanobiotechnology.

Newborn lambs depend on their dams for passive transfer of immunoglobulins, primarily IgG, for protection from harmful pathogens until their own immunological defenses have developed. Previous studies have suggested that supplementation with Se results in a modest increase in IgG concentration in serum of newborn calves and lambs. To evaluate the effect of the Se source and supplementation rate in ewes during pregnancy on passive transfer of IgG to their lambs, 210 Polypay, Suffolk, or Suffolk × Polypay cross ewes were divided into 7 treatment groups (n = 30 each) and drenched weekly with no Se, at the maximum FDA-allowed concentration with inorganic Na-selenite or organic Se-yeast (4.9 mg Se/wk), or with inorganic Na-selenite and organic Se-yeast at supranutritional concentrations (14.7 and 24.5 mg Se/wk). Ewe serum IgG concentrations were measured within 30 d of parturition, ewe colostrum and lamb serum IgG concentrations were measured at parturition before suckling, and lamb serum IgG concentrations were measured again at 48 h postnatal. Ewes receiving 24.5 mg Se/wk tended to have or had, independent of Se source, greater colostral IgG concentrations than ewes receiving 4.9 mg Se/wk overall (81.3 vs. 66.2 mg/mL; P = 0.08) and for Polypay ewes only (90.1 vs. 60.7 mg/mL; P = 0.03). Polypay ewes receiving Se-yeast at 24.5 mg Se/wk transferred a greater calculated total IgG amount to their lambs than Polypay ewes receiving Se-yeast at 4.9 mg Se/wk (15.5 vs. 11.6 g; P = 0.02), whereas the converse was true (interaction between Se source and dose concentration; P = 0.03) for Polypay ewes receiving inorganic Na-selenite at 24.5 mg Se/wk vs. Na-selenite at 4.9 mg/wk (11.6 vs. 15.7 g; P = 0.08). Our results suggest that supranutritional Se supplementation of Polypay ewes during pregnancy increases colostral IgG concentrations but that the optimal supplementation rate for IgG transfer from ewe to lamb may differ for Na-selenite and Se-yeast.

The present study aims to determine the effect of dietary Se supplement on Merghoz goats at the last stage of gestation on serum Se, Cu, Zn and Fe status of goats and their kids. Thirty Merghoz does (30 ± 3 kg) were fed the same basal diet containing 0.11 mg Se kg −1 DM and randomly assigned to one of three dietary treatments in a randomized complete block design. Three weeks before the expected kidding, the basal diet was supplemented with 0 (control) or 0.3 mg Se head −1 d −1 in the form of l -selenomethionin (Se-Met) and 0.3 mg Se head −1 d −1 in the form of sodium selenite (SS). Blood samples were collected from the does three weeks before the expected kidding and on the kidding day. Blood samples of newborn kids were also taken from the jugular vein at birth and 7 days of age. The results indicated that the serum concentration of Se increased in supplemented does compared with the control ones. The selenium concentration was also significantly increased in colostrum of treated does ( P P

Selenium is an essential micronutrient in sheep, and deficiency can limit lamb growth and survival. To evaluate how different chemical forms of Se administered to mature ewes at comparative dosages affect ewe and progeny performance, 240 ewes were divided into 8 treatment groups (n = 30 each) and drenched weekly with no Se; at the maximum FDA-allowed concentration with inorganic Na-selenite or organic Se-yeast (4.9 mg Se/wk); with inorganic Na-selenate (8.95 mg Se/wk); or with inorganic Na-selenite and organic Se-yeast at supranutritional concentrations (14.7 and 24.5 mg Se/wk, respectively). The treatment period started approximately 2 wk before breeding and lasted for 62.5 wk. Ewes of the no-Se and Se-yeast groups continued treatments for another 21 to 24 wk through a second lambing season. Chemical form or dosage of Se did not affect ewe reproductive performance based on proportion of ewes lambing in each treatment group, or number of lambs born, nursed, or weaned per ewe (all P > 0.10). Ewes receiving the highest supplementation rate of Se-yeast at 24.5 mg Se/wk had higher BCS (scale 1 to 5) at the end of yr 1 (2.95 vs. 2.66; P = 0.05) than ewes receiving Se-yeast at 4.9 mg Se/wk. Performance was better in lambs from ewes receiving Se-yeast at 24.5 mg Se/wk than in lambs from ewes receiving Se-yeast at 4.9 mg Se/wk or no Se. In yr 1, lambs from ewes receiving Se-yeast at 24.5 vs. 4.9 mg Se/wk were heavier at 120 d of age (37.0 vs. 34.2 kg; P = 0.05). In yr 2, lambs from ewes receiving Se-yeast at 24.5 mg Se/wk were or tended to be heavier at 60 d of age than lambs from ewes receiving no Se (21.2 vs. 19.0 kg; P = 0.04) or lambs from ewes receiving Se-yeast at 4.9 mg Se/wk (19.2 kg; P = 0.09). This effect was more pronounced in ewes raising multiple lambs. We conclude that supranutritional supplementation of ewes with Se-yeast at 24.5 mg Se/wk improves lamb growth and ewe health without negatively affecting reproductive performance.

An overview highlighting the anti-cancer potential of (bio-essential) selenium- and tellurium-containing species, with an emphasis on biological targets and mechanisms of action, is presented. Studies thus far have focused on selenium(II) compounds (along with – to a lesser extent – inorganic selenium and selenium nanoparticles) which often successfully exploit the inherent anti-oxidizing ability of selenium. Significantly less work has been conducted in developing anti-cancer tellurium compounds, yet two tellurium(IV) species are proven, clinically, as anti-cancer agents. Given the prevalence of the disease and the accumulated insights into mechanisms of action, the continued development of selenium- and tellurium-containing molecules is an area deserving greater attention. Copyright © 2012 John Wiley & Sons, Ltd.

Selenium was believed to be toxic to animals, however, in 1957, selenium was reported as a dietary vital nutrient. Selenium is available in inorganic and organic forms. In 1974, the Food and Drug Administration (FDA) regulated the supplementation of selenium in poultry diets. In 1994, the National Research Council recognized selenium as a dietary essential nutrient for laying hens. The maximum allowed selenium addition level is 0.30 mg/kg. One of the most common supplements used is sodium selenite (SS), the inorganic selenium source. However, in 2000, the FDA approved the use of the organic source of selenium, Se-enriched yeast (SY) in poultry diets. Selenium has valuable effects on animal immune status, growth parameters, production and reproduction. Experimentally, it has been indicated that SY benefits more than that of SS due to its more bioavailability. Selenium inclusion in food-animal diets has an extra nutritional advantage to human consumers of Se-enriched food-animal products.

A study was conducted to evaluate the effect of dietary selenium (Se) sources (organic and inorganic Se at 0.30 ppm and basal diet at 0 ppm level of supplemented Se) on hatching traits in four varieties of Aseel chicken, Lakha, Mushki, Peshawari, and Mianwali. In total, 84 adult molted hens (50 wk old), 21 from each variety, were randomly assigned to 12 treatment groups in a 3 (Se diets) × 4 (Aseel varieties) factorial arrangement under a randomized complete block design. Each treatment was replicated 7 times with individual hens in each. Settable egg, fertility, hatch of fertile eggs, hatchability, A-grade chick, and embryonic mortality parameters were evaluated. The results indicated that the birds fed an organic Se supplemented diet had greater (P 0.05) settable eggs, fertility, hatch of fertile eggs, hatchability, and A-grade chicks and reduced embryonic mortality than those fed inorganic or no Se. Among varieties, Mushki had lower (P 0.05) fertility, hatch of fertile eggs, hatchability, and A-grade chicks than rest of three varieties. Interaction of Se sources and varieties indicated that dietary organic Se supplementation improved (P 0.05) hatch of fertile eggs in Peshawari and Mianwali, whereas hatchability only in Peshawari variety and reduced embryonic mortality in Mianwali. It was concluded that dietary supplementation of organic Se could be used to improve hatching traits as well as reduce embryonic mortality in native Aseel chicken.

Selenium is an essential trace element in the diets which is required for maintenance of health, growth and biochemical-physiological functions. The area covered in this review has been rapidly unfolding in recent years and has already acquired a vast spread. This study presents a concise introductory overview of the effect of organic and inorganic selenium on growth performance, carcass traits, daily egg production, egg quality, Se uptake in various tissues and plasma and plasma glutathione peroxidase activity in animals.

Although the essentiality of dietary Se for sheep has been known for decades, the chemical source and Se dosage for optimal health remain unclear. In the United States, the Food and Drug Administration (FDA) regulates Se supplementation, regardless of the source of Se, at 0.3 mg of Se/kg of diet (as fed), which is equivalent to 0.7 mg of Se/d or 4.9 mg of Se/wk per sheep. The objectives of this study were to evaluate the effects of Se source (inorganic vs. organic) and supplementation rate (FDA vs. supranutritional rates of 14.7 and 24.5 mg of Se/wk) on whole-blood (WB) and serum-Se concentrations. Mature ewes (n = 240) were randomly assigned to 8 treatment groups (n = 30 each) based on Se supplementation rate (4.9, 14.7, and 24.5 mg of Se•wk(-1)•sheep(-1)) and source [Na-selenite, Na-selenate (4.9 mg/wk only), and organic Se-yeast] with a no-Se control group (0 mg of Se/wk). Treatment groups were balanced for healthy and footrot-affected ewes. For 1 yr, ewes were individually dosed once weekly with 0, 4.9, 14.7, or 24.5 mg of Se, quantities equivalent to their summed daily supplementation rates. Serum- and WB-Se concentrations were measured every 3 mo in all ewes; additionally, WB-Se concentrations were measured once monthly in one-half of the ewes receiving 0 or 4.9 mg of Se/wk. Ewes receiving no Se showed a 78.8 and 58.8% decrease (P < 0.001) in WB- (250 to 53 ng/mL) and serum- (97 to 40 ng/mL) Se concentrations, respectively, over the duration of the study. Whole-blood Se decreased primarily during pregnancy (-57%; 258 to 111 ng/mL) and again during peak lactation (-44%; 109 to 61 ng/mL; P < 0.001). At 4.9 mg of Se/wk, Se-yeast (364 ng/mL, final Se concentration) was more effective than Na-selenite (269 ng/mL) at increasing WB-Se concentrations (P < 0.001). Supranutritional Se-yeast dosages increased WB-Se concentrations in a dose-dependent manner (563 ng/mL, 14.7 mg of Se/wk; 748 ng/mL, 24.5 mg of Se/wk; P < 0.001), whereas WB-Se concentrations were not different for the Na-selenite groups (350 ng/mL, 14.7 mg of Se/wk; 363 ng/mL, 24.5 mg of Se/wk) or the 4.9 mg of Se/wk Se-yeast group (364 ng/mL). In summary, the dose range whereby Se supplementation increased blood Se concentrations was more limited for inorganic Na-selenite than for organic Se-yeast. The smallest rate (FDA-recommended quantity) of organic Se supplementation was equally effective as supranutritional rates of Na-selenite supplementation in increasing WB-Se concentrations, demonstrating the greater oral bioavailability of organic Se.

Adequate Se transfer from ewes to lambs is important to prevent Se-deficiency diseases. To evaluate how different chemical forms of Se admin- istered at comparative dosages to mature ewes affect Se status of their lambs, 240 ewes were divided into 8 treatment groups (n = 30 each) and drenched weekly (at an amount equal to their summed daily intake) with no-Se (controls); at recommended amounts (4.9 mg of Se/wk) with inorganic Na-selenite, inorganic Na-selenate, or organic Se-yeast; or at supranutritional amounts (14.7 and 24.5 mg of Se/wk) with Na-selenite or Se-yeast for 1 yr. Weekly drenching of Se was effec- tive at increasing (P < 0.002) Se concentrations in ewe colostrum and milk at 30 d of lactation and in improv- ing (P < 0.001) the Se status of lambs (whole-blood and serum-Se concentrations at birth, and skeletal-muscle Se concentrations at 14 d of age). Selenium concentra- tions in lacteal secretions were greater in ewes drenched with Se-yeast (colostrum: 374, 436, and 982 ng/mL at 4.9, 14.7, and 24.5 mg of Se/wk, respectively; milk: 26, 39, 64 ng/mL) compared with ewes drenched with Na- selenite (colostrum: 204, 334, 428 ng/mL; milk: 16, 21, 24 ng/mL), and were also greater (P < 0.001) in their lambs. Selenium concentrations continued to increase (P < 0.001) in lamb whole blood (558 and 695 ng/ mL at 14.7 and 24.5 mg of Se/wk, respectively), serum (126, 183 ng/mL), and skeletal muscle (991, 1,696 ng/ mL) with supranutritional concentrations of Se-yeast, whereas Se concentrations did not differ in whole blood (304, 332 ng/mL), serum (77, 85 ng/mL), or skeletal muscle (442, 482 ng/mg) of lambs from ewes drenched with 14.7 or 24.5 mg of Se/wk of Na-selenite. We con- clude that weekly oral drenching of ewes during ges- tation and lactation with organic Se-yeast results in a more efficient transfer of Se (over a wide range of supplementation rates) from ewe to lamb than does in- organic Na-selenite.

Construction and optimisation of a hyphenated analytical system for high performance liquid chromatography with hydride generation atomic absorption spectrometry detection system are described together with results of its use for investigation of food products. The use of anion-exchange chromatographic column permitted separation of inorganic selenium species Se(IV) and Se(VI) at the limit of detection of 10 ng mL−1 for both species. The analytical system was used for determination of selenium species in dietary supplements available on the Polish market. The content of inorganic selenium species was found not to exceed 50% of its total content, and in the majority of products, the dominant species was Se(IV). In the majority of products, the total contents of selenium were close to those declared by the producers.

A new method was established for the speciation of Se by hydride generation-atomic fluorescence spectrometry. Effective separation of organic and inorganic Se in Se-enriched eggs was achieved by precipitating albumen with trichloroacetic acid. The detection limit for Se was 0.07 μg L−1. The proposed method was successfully applied for the determination of organic and inorganic Se as well as total Se in Se-enriched eggs with the recovery of 90.1–112% and the relative standard deviation (n = 5) of 0.6–3.4%. Se in Se-enriched eggs presents mainly in organic forms, the content of which was three to seven times that of inorganic Se.

International audience; A method for the quantitation of proteinaceous selenocysteine (SeCys) in Se-rich yeast was developed. The method is based on the reduction of the Se-Se and S-Se bridges with dithiotretiol, derivatization with iodoacetamide (carbamidomethylation), followed by HPLC-ICP MS. The chromatographic conditions were optimized for the total recovery of the proteinaceous selenocysteine, the minimum number of peaks in the chromatogram (reduction of derivatization products of other Se-species present) and the baseline separation. A typical chromatogram of a proteolytic digest of selenized yeast protein consisted of up to five peaks (including SeMet, carbamidomethylated (CAM)-SeCys, and Se(CAM) 2) identified by retention time matching with available standards and electrospray MS. Inorganic selenium non-specifically attached to proteins and selenomethionine could be quantified (in the form of Se(CAM) 2) along with SeCys. Selenocysteine, selenomethionine, inorganic selenium, and the water soluble-metabolite fraction accounted for the totality of selenium species in Se-rich yeast.

Selenium has been recognized as an important element from the perspective of human health and environmental geochemistry because it is either essential or toxic depending on its concentration and c...

We have investigated a possibility of sorption concentration concurrently with fractionation of different valence forms of inorganic selenium during fluorimetric determination of its mass concentration in natural and drinking waters. We have also studied sorption of anions of tetra- and hexavalent selenium from the aqueous medium on the surface of anion-exchange sorbents. We have found optimal conditions of sorption and desorption of selenate- and selenite-anions on the strong-base anion-exchanger AV-17.

Tube-well water samples in several parts of the Northeastern region of Indian Punjab, where extensive cases of selenosis were reported earlier, have been analyzed for Se(IV) and Se(VI). The total s...

The study was conducted to determine the efficacy of organic Se from Se-enriched alga Chlorella spp. in placental transfer to piglets. In group A (n = 8) the sows were fed during the gestation a diet supplemented with inorganic Se (sodium selenite, 0.3 mg/kg). In group B (n = 8) the diet of the sows was supplemented with organic Se from Se-enriched alga (0.3 mg/kg). The Se concentrations in the whole blood (P < 0.05) and in colostrums (P < 0.05) were higher in the group of sows provided with the organic Se form. No differences in GSH-Px activities were found between the two groups. The concentrations of Se in piglet tissues were also higher when the organic form was provided. It is concluded that the use of the organic Se from Se-enriched alga Chlorella spp. in sows resulted in greater transfer of Se to their progeny.

The objective of this study was to compare the effects of feed supplementation with sodium selenite or selenized yeast on serum Se levels and reproduction indicators in cattle. In three beef herds young heifers, cows in late pregnancy, and their calves were randomly grouped by 6. In Herd 1, the mean Se serum levels were 51.01 μg l-1 in heifers, 32.12 μg l-1 in cows in late pregnancy, and 29.07 μg l-1 in their calves. In Herd 2, 27.42 μg l-1 (heifers), Z22.9 μg l-1 (late pregnancy), and 23.46 μg l-1 (calves). In Herd 3, 27.07 μg l-1 (heifers), 22 μg l-1 (late pregnant cows), and 31.05 μg l-1 (calves). Over a 6-month period, the animals in Herd 1 were given selenium yeast supplement; in Herd 2 sodium selenite, whereas Herd 3 served as a negative control. Afterwards, a second blood sample was taken. The mean Se serum levels were as follows: Herd 1 (selenium yeast): 90.73 μg l-1 in late pregnant cows ( p < 0.01), 57.99 μg l-1 in calves (p < 0.01); Herd 2 (sodium selenite): 42.08 μg l-1 (late pregnant cows p < 0.01), 37 μg l-1 (calves p < 0.05); Herd 3 (control) 25.77 μg l-1 (late pregnant cows), 32.85 μg l-1 (calves). A significant difference was also observed in the second blood sample taken in both the late pregnant cows and the calves between the Herds 1 and 2 (late pregnant cows p < 0.01, calves p < 0.01). No significant differences were demonstrated between the groups. Herds 1 and 2 showed an improvement in their health status, as compared with the previous period, neither in reproduction indicators nor in the weight gain of the calves.

The biochemistry, pharmacology and epidemiology of selenium and selenium-containing compounds continue to be subjects of considerable interest from the viewpoint of public health. Selenium has a long history of association with human health and disease, and we now recognize that this element is an essential nutrient that is critical to key cellular processes. We now know that the selenoproteins constituting the human selenoproteome are encoded by 25 genes in the human genome, and much progress is being made in our understanding of selenium metabolism and the health effects of selenium metabolites in normal and disease states. The idea that selenium-containing dietary supplements might be effective in preventing disease has gone through both optimistic and pessimistic phases in recent years, and the future prospects for such a nutritional approach are unclear at the present time. In contrast, a significant number of promising efforts are underway that are aimed at designing and developing pharmaceutical agents that are selenium-based or that target specific aspects of selenium metabolism. This chapter focuses on some of these efforts to develop new selenium-based anticancer, antioxidant, antihypertensive, antiviral, immunosuppressive, and antimicrobial agents. While most of the efforts that entail designed organoselenium compounds – as opposed to inorganic selenium metabolites – are still at the preclinical stage, evidence is emerging that selenium-based compounds can operate via several beneficial biochemical and pharmacological mechanisms. Since our understanding of the biology, biochemistry and pharmacology of selenium and selenoproteins is rapidly expanding, we can anticipate that the coming years will bring further development of new selenium-based pharmaceutical agents with therapeutic potential against human diseases.

For studying geochemical behavior of selenium, a marine investigation was conducted in September 1998 cruise in the Bohai Sea. Horizontal and vertical distributions of inorganic selenium and selenite were studied. The inorganic selenium varied from 0.73 to 2.41 nmol/L, with an average of 1.31 nmol/L; while selenite varied from 0.18 to 0.72 nmol/L with an average of 0.47 nmol/L. The average ratio of selenite to selenate was 0.68, and selenate was the predominant species of inorganic selenium in the most study area. Concentrations of inorganic selenium and selenite decreased with distance from the coast. No apparent variations of the concentration between surface and bottom was shown. There were two water masses in the area, one from the Huanghe (Yellow) River and other from the Yellow Sea. Of the two, Huanghe River was the major source of inorganic selenium.

Two cruises were undertaken to study the selenium species and arsenic, and their relationship with marine production in the Zhujiang (Pearl River) Estuary, covering both wet (July, 1999) and dry (January, 2000) seasons. Concentrations of dissolved Se (IV), Se (VI) and arsenic in the Zhujiang River are generally within the range of Chinese rivers and other large systems, like the Rhone River and Panama River. In January 2000, the concentration of selenium was lower than that in the July 1999. Total dissolved inorganic selenium averaged 2.77 nmol L−1 in the winter and 4.15 nmol L−1 in the summer, with Se (VI) accounting for 55% and 58%, respectively. Total dissolved inorganic arsenic averaged 25.8 nmol L−1 in the winter and 22.3 nmol L−1 in the summer. The data indicated that dissolved arsenic and selenium did not behave conservatively in the estuary. An important mobilization of dissolved selenium and arsenic was observed from the river up to halfway in the estuary. Both input flux (from river to estuary) and output flux (from estuary to coastal zone) of dissolved selenium and arsenic were calculated from statistical interpretations of the salinity profiles.

A method for the analysis of selenium in marine aquatic products by HG-AFS has been investigated. The method is based on the reduction of inorganic selenium to volatile SeH2 which is bubbled out by carrier gas of pure argon, and then swept to Ar-H2 flame quarts atomizer to measure its fluorescence intensity. The hydride generation, transportation, atomization and some instrumental parameters were studied by a kind of orthogonal design. The optimum conditions selected are as follows: reactive acidity, 20% HC1; the amount of NaBH4, 4.9mL; gas flow of argon, 6OO mLmin−1; atomizing temperature, 200°C, negative high voltage,−300V; light current, 100 mA; integral time, 7 s. The detection limit of the presented method is 0.072µgL−1 for selenium. The calibration curve shows a satisfactory line in the concentration range from 0.000 to l.OOOµgL−1 Se. The recovery is 95.8%–102.2% .

Two cruises of “R/V Dong Fang Hong 2” were carried out in September 1998 and May 1999, respectively, to understand the behavior of selenium in the Bohai Sea. Selenium species (dissolved inorganic selenium, selenite) are determined by HG-AFS for 30 grid stations. Selenium concentrations display short-term variability and seasonal change in the Bohai Sea, with higher levels in shallow coastal waters than in the Central Bohai Sea. The influence of riverine discharge on selenium levels can be seen from salinity isopleths, selenium distribution and species ratios. Near-bottom waters have similar selenium concentrations as to the surface waters in the Central Bohai Sea, whereas stratification takes place in the Bohai Strait and North Yellow sea. Based on the data of this study, a preliminary estimate of selenium budgets via riverine input is established. The seasonal variation of Se (IV)/Se (VI) ratio is maximum in Bohai Sea. The predominant species of selenium was selenate in autumn 1998. However, selenite became the dominant species in spring 1999. A simple box model was used to estimate the water-mass balance and selenium budgets for the Bohai Sea. Selenium budgets demonstrated that net sink of selenium can be mainly from the water column into bottom sediments and/or by transformation to other forms of selenium.

This experiment evaluated the maximum tolerable level of inorganic Se fed to growing wether lambs for 1 year. Sodium selenite was added to provide 0.2, 2, 4, 6, 8, and 10 ppm Se to a basal diet. Thirty-nine crossbred wether lambs initially weighing 22.8 ± 3.3 kg were randomly allotted to one of six treatments. Blood samples were collected and liveweight gain determined at 28-day intervals and tissue samples were collected at experiment termination. Serum, whole blood, wool, hooves, bile and five tissues were analyzed for Se concentrations. Five tissues at experiment termination were microscopically evaluated for tissue breakdown due to Se toxicosis. Also, five enzyme activities and albumin were determined. Lamb BW were not influenced by dietary Se concentrations ( P > 0.15). Both serum and whole blood Se concentrations increased at each collection period as dietary Se level increased ( P P r = 0.92) between serum and whole blood Se concentration. At termination of the study, all tissues and wool, hoof, and bile Se concentrations increased as dietary Se level increased ( P P > 0.15) among treatments, and enzymes were within their respective normal ranges. These results suggest that ≤10 ppm dietary Se as selenite is not toxic to wether lambs when fed for 1 year. It seems plausible, therefore, to consider the maximum tolerable level of Se as selenite for sheep to be considerably higher than 2 ppm as previously suggested.

1. Selenium (Se) is an essential part of numerous selenoproteins, most of which are involved in the antioxidant system of the body. It is also required by poultry for the maintenance of optimal health and meat quality. This paper reports data from a study examining the effect of dietary source and concentration of selenium on broiler performance and meat quality. 2. Increased dietary selenium content markedly reduced feed conversion ratio (FCR) as a result of significantly lower feed intakes of birds while maintaining the same weight gains. 3. Selenium supplementation increased feathering, with organic selenium (selenised yeast) being superior to inorganic selenium (sodium selenite). 4. Birds receiving organic selenium in their diets had improved eviscerated weight, breast yield and reduced drip loss. 5. There were significant concentration x source interactions on yields of breasts and marylands (thigh plus drumstick), with elevated levels of organic selenium increasing the yields, whereas the opposite was true for the inorganic selenium.

Using a flow-through photochemical reactor and a low pressure mercury lamp as a UV source, alkyl selenium species are formed from inorganic selenium(IV) in the presence of low molecular weight organic acids (LMW acids). The volatile alkyl Se species were cryogenically trapped and identified by GC-MS and GC-ICP-MS. In the presence of formic, acetic, propionic and malonic acids, inorganic selenium(IV) is converted by UV irradiation to volatile selenium hydride and carbonyl, dimethylselenide and diethylselenide, respectively. Se(IV) was successfully removed from contaminated agricultural drainage waters (California, U.S.A.) using a batch photoreactor system Se. Photochemical alkylation may thus offer a promising means of converting toxic selenium salts, present in contaminated water, to less toxic dimethylselenide. The LMW acids and photochemical alkylation process may also be key to understanding the source of atmospheric selenium and are likely involved in its mobility in the natural anaerobic environment.

The distribution and metabolism of an inorganic selenium (Se) compound and a selenoamino acid in quails were evaluated by speciation with inductively coupled plasma mass spectrometry (ICP-MS) and a stable isotope. Quails were orally administered stable isotope [(77)Se]-labeled selenite and selenomethionine (SeMet) at the nutritional dose of 10 μg Se/bird. Then, the quails were dissected 3, 9, and 24 h after the administration to examine the metabolic pathway and the time-dependent change of Se. The concentrations of exogenous Se in all the organs and tissues of the SeMet-administered group were significantly higher than those of the selenite-administered group 3 h after the administration. This suggested that SeMet was more rapidly and/or efficiently incorporated into the quail body than selenite. A Se-containing protein in the serum was detected only in the SeMet-administered quails, but not in the selenite-administered quails. The major urinary Se metabolite, i.e., Se-methylseleno-N-acetyl-galactosamine (selenosugar), was detected in the quail serum after the administration of both selenite and SeMet. The endogenous amount of Se-methylated selenosugar (MeSeSug) in the serum of quails seemed to be larger than that of the rodents. We conclude that the metabolic pathway of Se in quails was the same as that in rodents, but the metabolic capacity for Se seemed to be larger in quails than in rodents.

Selenium is an essential element for the normal cellular function of living organisms. However, selenium is toxic at concentrations of only three to five times higher than the essential concentration. The inorganic forms (mainly selenite and selenate) present in environmental water generally exhibit higher toxicity (up to 40 times) than organic forms. Therefore, the determination of low levels of different inorganic selenium species in water is an analytical challenge. Solid-phase extraction has been used as a separation and/or preconcentration technique prior to the determination of selenium species due to the need for accurate measurements for Se species in water at extremely low levels. The present paper provides a critical review of the published methods for inorganic selenium speciation in water samples using solid phase extraction as a preconcentration procedure. On the basis of more than 75 references, the different speciation strategies used for this task have been highlighted and classified. The solid-phase extraction sorbents and the performance and analytical characteristics of the developed methods for Se speciation are also discussed.

The importance of inorganic selenium and chromium speciation at low concentration levels is well established. Thus, society demands that accurate analytical methods be implemented in routine laboratories. In this context, the European Commission, through the Standards, Measurements and Testing Programme, has contributed significantly to improving the quality control of the speciation of inorganic selenium, as Se(IV) and Se(VI), and chromium, as Cr(III) and Cr(VI), by organising interlaboratory studies followed by the preparation of candidate reference materials. In this article are outlined the performance of the methods used by the participating laboratories and the main sources of errors detected.

Selenium in the form of selenocysteine plays an essential role in a number of proteins, but its role in non-enzymatic biochemistry is also important. In this short review we discuss the interactions between inorganic selenium, arsenic and mercury under physiological conditions, especially in the presence of glutathione. This chemistry is obviously important in making the arsenic and mercury unavailable for more toxic interactions, but in the process it suggests that a side-effect of chronic arsenic and/or mercury exposure is likely to be functional selenium deficiency.

The toxicity and essential nature of selenium in the environment depend on its concentration and on the chemical forms in which it is present. Dissolved inorganic selenium can be found in natural waters as selenides (Se-II), colloidal elemental selenium (Se0), selenite (SeIV) as well as selenate (SeVI). Organic forms of selenium that may be found in organisms, air or in the aqueous environment are volatile methylselenides, trimethylselenonium ion and selenoamino acids. This review article intends to show some general ideas in speciation analysis of selenium and to highlight some important procedures.

This paper describes the preparation of two artificial solutions containing inorganic SeIV (selenite) and SeVI (selenate), the homogeneity and stability studies and the analytical work performed for the tentative certification of the contents of total inorganic selenium, selenite and selenate. The results submitted by a group of EU laboratories are discussed, in addition to the methods used to determine the selenium species in solutions containing low (6 µg l–1) and high (50 µg l–1) analyte levels. Although the good agreement obtained by the laboratories would have permitted certification, the Se species were found not to be stable over a long-term period (36 months) in polypropylene bottles which hence hampered certification of these reference materials.

Inorganic selenium species were determined in several parts of a freshwater fish of the speciesTilapia nilotica found breeding in disused tin-mining pools. The inorganic selenium species in the monazite-rich ores can enter the human food chain through the consumption of the fish. The Se(IV) and Se(VI) species were preconcentrated by solvent extraction with APCDT-CHCl3 before irradiation in a TRIGA Mk.II reactor. Total inorganic selenium species separation was done using Chelex-100 chelating resin. Quantitative interpretations of the distribution of inorganic selenium species in the fish are discussed with particular reference to the Se(IV)/Se(VI) ratio.

International audience; The aim of this study was to compare the effects of a new organic Se [2-hydroxy-4-methylselenobutanoic acid (HMSeBA)] with routinely used mineral and organic Se sources (sodium selenite and selenized yeast) on chosen performance criteria and Se deposition in egg and muscle of laying hens. A total of 240 laying hens (40 wk of age) were randomly assigned to 6 treatments for 56 d with 8 replicates of 5 hens per replicate. The 6 treatments were as follows: control group received basal diet without Se supplementation; the second, fourth, and sixth experimental groups (SS-0.2, SY-0.2, and HMSeBA-0.2, respectively) were fed basal diet supplemented with Se at 0.2 mg/kg from sodium selenite, selenized yeast, and HMSeBA, respectively; and the third and fifth experimental groups (SY-0.1, and HMSeBA-0.1, respectively) were fed basal diet supplemented with Se at 0.1 mg/kg from selenized yeast and HMSeBA, respectively. No difference was observed among dietary treatments on feed intake, egg weight, and laying rate. All hens fed the Se-supplemented diets exhibited greater total Se contents in their eggs compared with control hens (P < 0.01). The egg Se concentrations were greater in hens fed organic Se (HMSeBA-0.2, P < 0.01, and SY-0.2, P < 0.01) than those fed the SS-0.2. In addition, hens fed the diet with HMSeBA-0.2 accumulated more Se in their eggs (+28.78%; P < 0.01) and muscles (+28%; P < 0.01) than those fed the diet supplemented with SY-0.2. These results showed the greater ability of HMSeBA to increase Se deposition in eggs and breast muscle of laying hens, which can subsequently lead to greater supply of Se for humans.