Tissue Selenium Concentrations Research Articles

Inorganic elements in green sea turtles (Chelonia mydas): relationships among external and internal tissues.

Inorganic elements from anthropogenic sources have entered marine environments worldwide and are detectable in marine organisms, including sea turtles. Threatened and endangered classifications of sea turtles have heretofore made assessments of contaminant concentrations difficult because of regulatory restrictions on obtaining samples using nonlethal techniques. In the present study, claw and skin biopsy samples were examined as potential indicators of internal tissue burdens in green sea turtles (Chelonia mydas). Significant relationships were observed between claw and liver, and claw and muscle concentrations of mercury, nickel, arsenic, and selenium (p < 0.05). Similarly, significant relationships were observed between skin biopsy concentrations and those in liver, kidney, and muscle tissues for mercury, arsenic, selenium, and vanadium (p < 0.05). Concentrations of arsenic, barium, chromium, nickel, strontium, vanadium, and zinc in claws and skin biopsies were substantially elevated when compared with all other tissues, indicating that these highly keratinized tissues may represent sequestration or excretion pathways. Correlations between standard carapace length and cobalt, lead, and manganese concentrations were observed (p < 0.05), indicating that tissue concentrations of these elements may be related to age and size. Results suggest that claws may indeed be useful indicators of mercury and nickel concentrations in liver and muscle tissues, whereas skin biopsy inorganic element concentrations may be better suited as indicators of mercury, selenium, and vanadium concentrations in liver, kidney, and muscle tissues of green sea turtles.

셀레늄 강화 청보리 사일리지 급여가 비육기 거세한우의 생산성, 혈액성상 및 도체특성과 조직 내 셀레늄 축적에 미치는 영향

본 연구는 다양한 수준의 셀레늄 강화 청보리 사일리지와 무기셀레늄을 급여 시 비육기 거세한우의 생산성, 혈액 성상, 도체특성 및 조직 내 셀레늄 축적에 미치는 영향을 조사하였다. 시험은 거세비육우 20두를 공시하였고, 처리구는 셀레늄 수준에 따라 0.1 ppm Se(대조구), 0.3 ppm Se (T1), 0.9 ppm Se (T2) 및 무기셀레늄 0.9 ppm Se (T3) 급여구로 4처리를 나누어 처리구 구당 5두씩 완전임의 배치하여 90일간 사양시험을 실시하였다. 각 시험사료는 셀레늄 강화 및 셀레늄 무처리 관행 청보리 사일리지를 조합하여 건물기준 30% 함유하도록 배합하였다. 실험사료 내에 셀레늄 강화수준은 사료섭취량과 증체에 영향을 미치지 않았고, 혈중 총 지질과 중성지방농도는 대조구보다 T2구가 유의하게 낮았다(p<0.05). 혈중 면역글로불린은 셀레늄함유량이 많을수록 높게 나타나 T2와 T3구가 대조구보다 유의하게 높았다(p<0.05). 혈중 셀레늄농도는 유기태 셀레늄을 0.9 ppm 급여한 T2구가 가장 높았다(p<0.05). 도체율, 배최장근, 등지방두께, 근내지방도, 육색 및 지방색은 셀레늄급여로 인한 효과가 나타나지 않았다. 또한, 사료 내 셀레늄 수준 및 형태는 육질 및 육량등급 간에 관련성이 형성되지 않았다. 신장, 간장 및 후지 내 셀레늄 함량은 사료 내 셀레늄 강화수준이 증가함에 따라 유의하게 직선적으로 증가하였고(p<0.05), 무기셀레늄급여는 대조구와 유의한 차이가 나타나지 않아, 조직 내 셀레늄함량 증가에 도움이 되지 않았다(p>0.05). 이상의 결과에서 셀레늄 강화 청보리 사일리지 내 존재하는 셀레늄은 조직 내 셀레늄함량을 증가시키기에 유효한 셀레늄급원인 것으로 나타났고, 셀레늄 강화 청보리 최고수준(0.9 ppm Se)으로 급여하여 생산된 한우 후지육 100 g에 함유되어 있는 셀레늄은 성인기준 1일 최소 셀레늄 권장량(<TEX>$40{\mu}g$</TEX>)의 약 69%를 충족시키는 것으로 조사되었다. This study was conducted to investigate the effects of feeding seleniferous whole crop barley silage (WCBS) on the growth performance, blood and carcass characteristics, and tissue selenium deposition infinishing Hanwoo steers. A total of 20 growing Hanwoo steers were selected and assigned to one of the following feed groups: control (0.1 ppm Se), T1 (0.3 ppm Se), T2 (0.9 ppm Se), and T3 (0.9 ppm of inorganic Se). Five steers were allocated to each treatment group, and the trial lasted for 90 days. All experimental diets combined seleniferous and/or non-seleniferous WCBS up to a ratio of 30%. For the T3 diet, 0.9 ppm Se in the form of sodium selenite was added to the control diet. Dietary level and type of selenium did not affect feed intake and body weight gain. Blood total lipid and triglyceride concentrations were significantly (p<0.05) lower in the T2 group than in control. Blood immunoglobulin G concentration increased significantly (p<0.05) with increasing levels of dietary selenium; concentrations were significantly (p<0.05) higher in T2 and T3 than in control. Blood selenium concentration was the highest (p<0.05) in T2. No significant difference was observed in dressing rate, ribeye area, marbling score, meat color and fat color. Further, no association was found between levels and chemical form of dietary selenium and quality and quantity of meat. To the contrary, tissue selenium content in kidney, liver, and hind leg increased significantly (p<0.05) with increasing levels of selenium; however, feeding inorganic selenium did not introduce a significant increase in tissue selenium content of finishing Hanwoo steers. The results indicated that the selenium present in seleniferous WCBS was an effectively absorbable selenium source, suitable for increasing tissue selenium content in beef. Approximately 100 g of hind leg muscle from steers fed on the T2 diet met approximately 69% of the recommended daily selenium requirements.

Enhanced selenium content in wheat grain by co-inoculation of selenobacteria and arbuscular mycorrhizal fungi: A preliminary study as a potential Se biofortification strategy

Cereal crops grown in southern Chilean Andisol provide suboptimal levels of this metalloid for human diet. Certain rhizosphere microorganisms, such as rhizobacteria and arbuscular mycorrhizal fungi can increase the selenium uptake in plants. The purpose of this study was to evaluate selenium acquisition by wheat plants through the co-inoculation of native selenobacteria strains (Stenotrophomonas sp. B19, Enterobacter sp. B16, Bacillus sp. R12 and Pseudomonas sp. R8), both individually and in mixture, as selenonanosphere source with one arbuscular mycorrhizal fungus (Glomus claroideum). Total selenium content in plant tissues and substrate was analyzed. According to our results, significant higher selenium content was found in inoculated plants in comparison to uninoculated controls (P ≤ 0.05). Independently of fungal presence, selenium content in grain from plants inoculated with Enterobacter sp. B16 (236 mg kg−1) was higher than the rest of the strains (116–164 mg kg−1). However, when plants were co-inoculated with a mixture of selenobacteria strains and G. claroideum, selenium content in grain was 23.5% higher (725 mg kg−1) than non-mycorrhizal plants (587 mg kg−1). The results suggest a synergistic effect between the selenobacteria mixture and G. claroideum associated to major biodiversity and demonstrate a great potential of these rhizosphere microorganisms for biofortification of cereals and its derivates.

Production of Selenoprotein P (Sepp1) by Hepatocytes Is Central to Selenium Homeostasis

Sepp1 transports selenium, but its complete role in selenium homeostasis is not known. Deletion of Sepp1 in hepatocytes increases liver selenium at the expense of other tissues and decreases whole-body selenium by increasing excretion. Sepp1 production by hepatocytes retains selenium in the organism and distributes it from the liver to peripheral tissues. Sepp1 is central to selenium homeostasis. Sepp1 is a widely expressed extracellular protein that in humans and mice contains 10 selenocysteine residues in its primary structure. Extra-hepatic tissues take up plasma Sepp1 for its selenium via apolipoprotein E receptor-2 (apoER2)-mediated endocytosis. The role of Sepp1 in the transport of selenium from liver, a rich source of the element, to peripheral tissues was studied using mice with selective deletion of Sepp1 in hepatocytes (Sepp1(c/c)/alb-cre(+/-) mice). Deletion of Sepp1 in hepatocytes lowered plasma Sepp1 concentration to 10% of that in Sepp1(c/c) mice (controls) and increased urinary selenium excretion, decreasing whole-body and tissue selenium concentrations. Under selenium-deficient conditions, Sepp1(c/c)/alb-cre(+/-) mice accumulated selenium in the liver at the expense of extra-hepatic tissues, severely worsening clinical manifestations of dietary selenium deficiency. These findings are consistent with there being competition for metabolically available hepatocyte selenium between the synthesis of selenoproteins and the synthesis of selenium excretory metabolites. In addition, selenium deficiency down-regulated the mRNA of the most abundant hepatic selenoprotein, glutathione peroxidase-1 (Gpx1), to 15% of the selenium-replete value, while reducing Sepp1 mRNA, the most abundant hepatic selenoprotein mRNA, only to 61%. This strongly suggests that Sepp1 synthesis is favored in the liver over Gpx1 synthesis when selenium supply is limited, directing hepatocyte selenium to peripheral tissues in selenium deficiency. We conclude that production of Sepp1 by hepatocytes is central to selenium homeostasis in the organism because it promotes retention of selenium in the body and effects selenium distribution from the liver to extra-hepatic tissues, especially under selenium-deficient conditions.

Effects of Selenium Source and Level on Growth Performance, Tissue Selenium Concentrations, Antioxidation, and Immune Functions of Heat-Stressed Broilers

An experiment is conducted to investigate the effects of selenium (Se) source and level on growth performance, tissue Se concentrations, antioxidation, and immune functions of heat-stressed broilers from 22 to 42 days of age. A total of 210 22-day-old Arbor Acres commercial male chicks were assigned by body weight to one of seven treatments with six replicates of five birds each in a completely randomized design involving a 3 × 2 factorial arrangement plus one Se-unsupplemented basal diet control (containing 0.027 mg of Se/kg). The three Se sources were sodium selenite (Na₂SeO₃), Se yeast, and AMMS Se (Se protein), and the two supplemental Se levels were 0.15 or 0.30 mg Se/kg. All birds were reared under heat-stressed condition (33 ± 1 °C during 0900-1700 hours and 27 ± 1 °C during 1900-0700 hours with a relative humidity of 60-80 %). The results showed that heat-stressed chicks fed Se-supplemented diets had higher (P < 0.10) average daily feed intake, Se concentrations in liver and breast muscle, liver glutathione peroxidase (GSH-Px) activity, serum antibody titers against H5N1(Re-4 strain), H5N1(Re-5 strain) and lower (P < 0.01) mortality compared with the control. Chicks fed the diets supplemented with 0.30 mg/kg of Se had higher (P < 0.05) Se concentrations in liver and breast muscle, liver GSH-Px activity, and serum antibody titer against H5N1 (Re-4 strain) than those fed the diets supplemented with 0.15 mg/kg of Se. Broilers fed the diets supplemented with Se yeast had higher (P < 0.001) Se concentrations in liver and breast muscle than those fed the diets supplemented with Na₂SeO₃ or AMMS Se. However, broilers fed the diets supplemented with AMMS Se had higher (P < 0.05) serum antibody titers against H5N1 (Re-4 strain) and H5N1 (Re-5 strain) than those fed the diets supplemented with Na₂SeO₃. These results indicated that Se yeast was more effective than Na₂SeO₃ or AMMS Se in increasing tissue Se retention; however, AMMS Se was more effective than Na₂SeO₃ or Se yeast in improving immune functions of heat-stressed broilers.

Effects of nano-selenium on performance, meat quality, immune function, oxidation resistance, and tissue selenium content in broilers

This study was conducted to investigate the effect of nano-selenium (nano-Se) on performance, meat quality, immune function, oxidation resistance, and tissue selenium content in broilers. A total of five hundred forty 1-d-old male Arbor Acres broilers were randomly allotted to 1 of 5 treatments with each treatment being applied to 6 replicates of 18 chicks. The 5 treatments consisted of corn-soybean meal-based diets supplemented with 0.0, 0.3, 0.5, 1.0, or 2.0 mg/kg of nano-Se. The selenium content of the unsupplemented control diet was 0.09 mg/kg for the starter phase (0 to 21 d) and 0.08 mg/kg for the grower phase (22 to 42 d). There were no significant differences (P > 0.05) in performance, meat color, or immune organ index (thymus, bursa, and spleen) due to supplementation with nano-Se. On d 42, a significant quadratic effect of nano-Se was observed on glutathione peroxidase activity, free radical inhibition, contents of IgM, glutathione, and malondialdehyde in serum, on glutathione peroxidase activity, free radical inhibition in liver, and on glutathione peroxidase activity in muscle, with birds fed 0.30 mg/kg of nano-Se exhibiting the best effect and birds fed 2.0 mg/kg of nano-Se showing the worst effect on these parameters. Liver and muscle selenium content increased linearly and quadratically as the dietary nano-Se level increased (P < 0.01), and reached the highest value when 2.0 mg/kg of nano-Se was fed. Based on a consideration of all experiment indexes, 0.3 to 0.5 mg/kg is suggested to be the optimum level of supplementation of nano-Se, and the maximum supplementation of nano-Se could not be more than 1.0 mg/kg in broilers.

Assessment of Mercury and Selenium Concentrations in Tissues of Stranded Leatherback Sea Turtles (Dermochelys coriacea)

The impact of mercury (Hg) and selenium (Se) compounds on wildlife health is an issue of concern, especially because anthropogenic practices (e.g., fossil fuel combustion, metal processing) release these trace elements and their compounds into the environment where they become incorporated into food chains. Little is known about the concentrations of these elements in tissues (other than in blood) of most wild reptiles, especially for pelagic species. The purpose of this study was to document Hg and Se concentrations in leatherback sea turtles, Dermochelys coriacea. To assess Hg and Se concentrations in leatherbacks, multiple tissue samples (whole blood, enteric contents from the small intestine, feces, yolked follicles, liver, and salt gland) were collected from dead, stranded male and female leatherbacks that were assigned to three life stage classes (juvenile, subadult, adult) identified at gross necropsy. The tissues were tested for Hg and Se concentrations. The liver exhibited the highest concentrations of both Hg and Se compared with other tissues. Adults had the highest concentrations of Hg in their livers compared with juveniles and subadults; however, Se concentrations did not differ between subadults and adults. Leatherbacks with a larger curved carapace length had greater liver Hg and Se concentrations. The Se:Hg ratio in the liver was highest in juveniles, followed by subadults, and then adults. Because these animals are long-lived, Hg or Se accumulation may become a physiological challenge, especially because of ongoing anthropogenic input of these elements and their compounds into the environment. Further population monitoring of toxicants in marine turtles is warranted to determine whether tissue concentrations of these elements continue to increase long term or vary with age, life stage, sex, or reproductive status.

Determination of Metal (Cu, Zn, Se, Cr and Cd) Levels in Tissues of the Cyprinid Fish, Capoeta trutta (Heckel, 1843) from Different Regions of Keban Dam Lake (Euphrates-Turkey)

The aim of this study was to evaluate Copper (Cu), Zinc (Zn), Selenium (Se), Chromium (Cr) and Cadmium (Cd) concentrations in liver, muscle, gills and kidney tissues of Capoeta trutta collected from four sites of Keban Dam Lake, Turkey. The highest heavy metal level in all tissues was for Zn, while Cd was the lowest. The lowest heavy metal levels were generally found at Station 4 (Agin) for all tissues (p<0.05). There were statistically significant differences among stations for Cu, Zn, Cr and Se in gills; for Cu, Zn, Se and Cr in liver and kidney; and Cu, Zn and Cr in muscle (p<0.05). Cadmium concentrations did not differ between sites for any of the tissues. Turkish Food Codex sets the maximum limits of Zn, Cu and Cd as, 50, 20 and 0.05mgkg(-1) dry weight, respectively, in the muscle of fish used for human consumption. In our study, the level of Zn was higher than Turkish permissible limits only at Station 3 (Guluskur). Cadmium levels were much higher than permissible limits at three stations [S1 (Pertek), S2 (Kockale) and S3], whereas Cu levels were within permissible limits in all stations.

A Case-Control Study of the Risk of Cutaneous Melanoma Associated with Three Selenium Exposure Indicators

A direct association between exposure to the metalloid selenium and risk of cutaneous melanoma has been suggested by some observational and experimental cohort studies, whereas other studies have yielded inconsistent results. Since some of the inconsistencies may be due to exposure misclassification arising from the use of exposure indicators that do not adequately reflect body tissue selenium content or the levels of the biologically relevant species of this metalloid, we examined this issue using multiple indicators of exposure. We analyzed the relation of selenium exposure with risk of cutaneous melanoma using two different biomarkers, plasma and toenail selenium concentration, and estimated dietary selenium intake in a population-based case-control series (54 cases, 56 controls) from an Italian community. In unmatched and matched logistic regression models as well as nonparametric generalized additive models, higher plasma selenium levels were strongly associated with excess disease risk. In contrast, toenail and dietary selenium exhibited little relation with melanoma risk. The pattern of correlation among indicators of exposure differed by disease status, with dietary intake associated with plasma selenium levels in patients but not in controls. Our data showed that different selenium exposure indicators can yield different inferences about melanoma risk. Although the series was small, our results are consistent with a positive association between circulating levels of selenium and melanoma risk. Further investigation of the exposure classification performance of various selenium biomarkers and of metabolic patterns of the metalloid and of its speciation are needed to help elucidate the relation between selenium exposure and human health.

Tissue selenium concentration increases slowly in critically ill patients compared with plasma

Tissue selenium concentration increases slowly in critically ill patients compared with plasma

Changes in the antioxidant defence and in selenium concentration in tissues of vanadium exposed rats

Vanadium is an element whose role as a micronutrient for humans is not yet completely established, but which has been shown to possess hypoglycaemic properties in diabetes. In an earlier study, we showed that in STZ-diabetic rats, exposure to 1 mg V per day has no effect on glycaemia or on antioxidant status. When the exposure was raised to 3 mg V per day there was a hypoglycaemic effect, together with reduced Se in the tissues, which reduced antioxidant defences. The aim of the present study was to examine whether exposure to 1 mg V per day modifies Se nutritional status and/or antioxidant defences in healthy rats. Two groups of rats were examined: control and vanadium-treated. Vanadium, as bis(maltolato)oxovanadium(iv), was supplied in the drinking water. The experiment had a duration of five weeks. Selenium was measured in excreta, serum, skeletal muscle, kidneys, liver, heart, femur and adipose tissue. Number of red (RBC) and white (WBC) blood cells and haemoglobin (Hb) were determined in samples of whole blood. Glutathione peroxidase (GPx), glutathione transferase (GST), catalase (CAT) and NAD(P)H:quinine-oxidoreductase1 (NQO1) activity, and malondialdehyde (MDA) in the liver were evaluated. Treatment significantly reduced food intake, produced an anaemic state, and decreased Se absorption and Se content in serum, kidneys and the liver. GPx, GST and NQO1 activity were decreased in the liver, while MDA levels rose. We conclude that healthy rats are more sensitive than diabetic ones to the effects of V. This should be taken into account for populations that are particularly exposed to V for environmental reasons, and/or that consume V as a nutritional supplement.

Effects of organic selenium supplementation on growth performance, carcass measurements, tissue selenium concentrations, characteristics of reproductive organs, and testis gene expression profiles in boars1

The objective was to compare growth and physiological responses in boars fed diets supplemented with organic or inorganic sources of Se. At weaning, crossbred boars (n = 117; 8.3 kg of BW) were placed in nursery pens (3 boars/pen) and assigned within BW blocks to receive on an ad libitum basis 1 of 3 dietary treatments: I) basal diets with no supplemental Se (controls), II) basal diets supplemented with 0.3 mg/kg of organic Se, and, III) basal diets supplemented with 0.3 mg/kg of sodium selenite (13 pens/dietary treatment). Average daily gain (470 g/d), ADFI (896 g/d), and G:F (0.54) were similar among groups. Blood Se concentrations were greater (P < 0.01) for boars consuming organic Se (107.5 ± 4.8 µg/L) or sodium selenite (114.7 ± 4.8 µg/L) compared with controls (28.4 ± 4.8 µg/L). Intact pens of boars (11 pens/dietary treatment) were moved to a grow-finish barn and continued to receive appropriate diets on an ad libitum basis. Average daily gain (1,045 g/d) and ADFI (2,716 g/d) were similar among groups. Gain:feed was affected by treatment (P = 0.02) and was greater (P < 0.06) for boars fed organic Se (0.378 ± 0.004) compared with boars fed sodium selenite (0.368 ± 0.004) or controls (0.363 ± 0.004). Blood Se concentrations were greater (P < 0.01) in grow-finish boars consuming organic Se (198.9 ± 5.5 µg/L) than boars consuming sodium selenite (171.4 ± 5.4 µg/L) or controls (26.7 ± 5.4 µg/L). Treatment did not affect (P > 0.15) HCW, dressing percent, carcass length, LM area, standardized fat-free lean, lean percentage, backfat thickness, visual color, firmness, marbling, or Minolta loin color scores. Selenium supplementation did not affect (P > 0.17) testis or accessory sex gland sizes. Concentrations of Se in loin, liver, kidney, testis, cauda epididymis, and accessory sex glands were greatest (P < 0.01) in boars receiving organic Se, intermediate in boars receiving sodum selenite, and least in control boars. Microarray analysis of testis gene expression did not detect differences (P > 0.05) due to dietary treatment. Testis gene expression of glutathione peroxidase 4, as determined using quantitative PCR, was increased (P < 0.01) in boars fed organic Se compared with those fed sodium selenite. In summary, dietary supplementation of boars with organic Se failed to alter ADG or ADFI but enhanced G:F during grow-finish. More research is needed to discern the mechanism by which organic Se improves feed efficiency in boars.

Acute selenium toxicosis in polo ponies

Just prior to an international polo event, 21 horses from one team exhibited clinical signs of central nervous system disturbance, hyperexcitability, sweating, ataxia, tachycardia, dyspnea, pyrexia, and rapid death. The suspected cause of this peracute onset of illness and death included intentional contamination of feed or iatrogenic administration of performance-enhancing drugs resulting in a severe adverse reaction. Six horses were submitted to the Bronson Animal Disease Diagnostic Laboratory for necropsy and toxicological examination. The clinical signs and sudden death, the similarity to earlier work by the lead author of selenium toxicosis in calves, as well as published reports, prompted investigators to focus on selenium testing. Sixty-four hours following receipt, the laboratory detected toxic selenium concentrations in the tissues of these animals. Following further investigation of the case by regulatory officials, it was determined that all affected horses had received an intravenous injection of a compounded "vitamin/mineral" supplement just prior to the onset of signs. The compounded supplement contained toxic levels of selenium. The present report illustrates the in-depth laboratory investigation of the cause of acute death in 6 polo ponies due to selenium toxicosis. In addition to solving this high profile case, the toxic levels of selenium found in livers (6.13 ± 0.31 mg/kg wet weight), kidneys (6.25 ± 0.3 mg/kg wet weight), and sera (1.50 ± 0.11 µg/ml) of these affected animals may provide important diagnostic criteria for future interpretations of selenium concentrations in tissues of horses.

Serum and lung tissue selenium measurements in subjects with lung cancer from Xuanwei, China

背景与目的宣威是我国肺癌高发区，有研究发现肿瘤的死亡率与硒的地理分布及摄入量呈负相关，肺癌死亡率与血硒水平呈负相关。本研究通过检测宣威肺癌患者的血清硒含量和肺组织硒水平，以初步探讨宣威地区肺癌高发与硒的关系。方法取120例宣威女性的血清，其中试验组为60例肺癌患者，对照组为60例非肿瘤非呼吸道疾病人群，测定其血清硒水平。术中取60例肺癌患者的肺癌组织、癌旁肺组织和正常肺组织，其中31例来自于宣威地区，29例来自于非宣威地区，分析癌组织、癌旁组织及正常组织的硒含量。血清和组织硒均采用荧光法进行测定。结果宣威地区女性肺癌患者血清硒含量为（55.22±13.34）μg/L，低于对照组（60.33±13.82）μg/L（P < 0.05）。宣威地区肺癌组织硒含量为（0.105±0.034）μg/g，低于正常肺组织（0.140±0.048）μg/g（P < 0.05）。宣威地区和非宣威地区肺癌组织、癌旁肺组织和正常肺组织间硒水平无统计学差异。腺癌和鳞癌、不同分期的肺癌组织、癌旁肺组织和正常肺组织之间的硒水平均无统计学差异。结论宣威地区肺癌的发生与低血硒状态有关，肺组织细胞低硒可能是导致癌变的潜在危险因素。

The effects of dietary selenium on growth performances, oxidative stress and tissue selenium concentration of gibel carp (Carassius auratus gibelio)

A 100-day growth trial was executed to determine the dietary selenium (Se) requirement of juvenile gibel carp (Carassius auratus gibelio). Selenomethionine was supplemented to casein-gelatin diets at 0, 0.1, 0.25, 0.5, 1.0, 2.5 and 5 mg Se kg(-1), respectively. Each of these seven semi-purified diets containing 0.34, 0.47, 0.66, 0.82, 1.23, 2.77 and 5.13 mg Se kg(-1) was fed to triplicate groups of gibel carp (2.74 +/- 0.02 g) in a flow-through system. No behaviour abnormalities and no mortality were found in fish exposed to dietary Se concentrations. With the increasing dietary Se supplemented concentrations, weight gain of fish remarkably increased at the levels of l= 1 mg Se kg(-1) diet and then showed no significant difference above 1 mg Se kg(-1) levels. Although growth performances (weight gain, hepatosomatic index, condition factor and survival) were not impaired in gibel carp fed at above the levels of 2.5 mg Se kg(-1), indicators of oxidative stress were changed significantly. Serum superoxide dismutase (SOD) activities significantly declined, hepatic glutathione peroxidase (GPx) activities significantly increased and the tissue Se concentrations significantly raised at the highest supplemented level of 5 mg Se kg(-1). A clear linear relationship between Se-depended GPx activities and hepatic Se concentrations was observed. The present results indicated that the dietary Se requirement for gibel carp is 1.18 mg Se kg(-1) diet based on weight gain, GPx activities and tissue accumulation.

The effects of soybean selenium proteinate on tissue selenium and meat quality traits in finishing pigs

The purpose of the present study was to evaluate the effects of soybean selenium proteinate on Se tissue retention and meat quality in pigs. In group A (n = 11) the mixtures were supplemented with soybean selenium proteinate, in group B (n = 11) with sodium selenite and in group C (n = 11) with Se-enriched yeast (0.3 mg Se per kg in all groups). The use of soybean selenium proteinate resulted in lower retention of Se in tissues (liver, heart, muscle) compared to Se-enriched yeast. Selenium concentrations in tissues achieved by soybean selenium proteinate and sodium selenite were comparable. No differences in serum Se, serum GSH-Px and meat quality traits were found among the groups.

Galvanostatic Stripping Chronopotentiometric Study for Determination of Selenium: Pharmacokinetic Application in Experimental Mice

The aim of this study was to determine the selenium content in various tissues of the mouse employing the galvanostatic stripping chronopotentiometry (SCP) technique and to investigate the distribution profile of selenium as well as its pharmacokinetics in a mouse model. The animals received 0.25 μg/g Se orally for 5 days. Samples of whole blood and various tissues comprising kidney, liver and brain were harvested from mice and then analysed for Se content employing the SCP technique. The SCP method was validated over Se concentration range of 10 – 100 ng/mL and showed good linearity (r² > 0.999). The precision (over 5 days) of the assay in various mouse tissues (liver, kidney, and brain) ranged from 0.03 to 2.9% with accuracy results that varied from -6.69 to 0.28%. The mean (n = 5) recoveries of Se from the mouse tissues ranged from 93.31 to 100.28%. The lower limit of Se detection in the mouse tissues was 0.2 ng/mL. The present method was successfully applied in evaluating the distribution of Se in various tissues as well as its pharmacokinetics in the mouse model. The Se tissue concentrations in the mouse model showed that the maximum Se levels in most tissues were attained within 3-4 days following its administration. Furthermore, the pharmacokinetic profile of Se in the mouse model indicates that the element is slowly absorbed from the gastrointestinal tract (GIT) reaching a plateau in 4 days and then it is slowly eliminated from the body with a half-life of about 4.5 days. The present SCP method was employed to analyse Se in various mouse tissues. The method was characterized by excellent performance parameters necessary for the determination of Se in biological matrices. Se distributes in whole blood as well as into various tissues of the mouse with high concentrations in the kidney and liver and low levels in the blood and brain tissues. The absorption of Se from the GIT was very slow and the data suggest that the elimination of Se seems to be through the kidney at a very slow rate as well. The data of the present study thus suggest that Se remains in the mouse body for a long period of time.

Does proximity to coal-fired power plants influence fish tissue mercury?

Much of the mercury contamination in aquatic biota originates from coal-fired power plants, point sources that release mercury into the atmosphere. Understanding mercury dynamics is primarily important because of the toxic threat mercury poses to wildlife and humans through the consumption of contaminated fish. In this study, we quantified the relative importance of proximity to coal-fired power plants on mercury accumulation in two fish species of different trophic positions. Fish, water and sediment were collected and analyzed from 14 lakes, seven near to (<10 km) and seven far from (>30 km) coal-fired power plants. Lower tissue mercury and higher tissue selenium concentrations were measured in fish collected near power plants. Moreover, mercury accumulation in fish was driven by biotic characteristics (e.g., trophic position, total length, age), waterbody characteristics (e.g., pH, dissolved organic carbon and sulfate) and distance from power plants. Proximity to an atmospheric point-source of mercury and selenium, such as a coal-fired power plant, affects the quantities of mercury and selenium accumulated in fish tissue. Differences in accumulation are hypothesized to be driven in part by selenium-mitigated reductions in fish tissue mercury near power plants. Although reduced fish tissue mercury in systems near power plants may decrease mercury-specific risks to human consumers, these benefits are highly localized and the relatively high selenium associated with these tissues may compromise ecological health.

Quality of meat and selenium content in tissues of rabbits fed diets supplemented with sodium selenite, selenized yeast and selenized algae

Forty rabbits weaned at 35 d of age were randomly assigned to 4 groups of 10 rabbits each. The rabbits were fed a basal granulated diet containing 0.08 mg Se/kg, or diets obtained from basal diet, supplemented with sodium selenite, selenized yeast (Se-yeast) or selenized algae Chlorella (Se-algae) to increase the Se concentration to 0.40 mg/kg. After 6 weeks rabbits were slaughtered at 77 d of age. Samples of meat, liver and hair were analyzed. The Se supplements did not influence rabbit growth, feed intake and weight loss during cooling. The nutrient composition of meat (dry matter, protein and fat concentration) was only marginally influenced. The Se concentration in the loin and hindleg meat increased by 23.0% and 19.2%, respectively in rabbits receiving the selenite supplement. In rabbits fed Se-yeast and Se-algae, the Se content in meat doubled from 0.11-0.15 mg/kg to 0.24-0.29 mg/kg. High Se concentrations (=1 mg/kg) were observed in hair and liver of rabbits which had received the Se-supplements. In all supplemented groups, the activity of glutathione peroxidase in the loin meat was higher than in control rabbits by 51.9-72.8% (P<0.001). The oxidative stability of rabbit meat, however, was not influenced. It follows from our results that (i) the enrichment of meat with Se is the main benefit of supranutritional Se supply in rabbits, and (ii) Se-yeast and Se-algae are more effective in increasing Se content in tissues than selenite.

Correlation between selenium concentrations and glutathione peroxidase activity in serum and human prostate tissue

Low serum selenium concentration has been associated with increased risk of prostate cancer. A possible mechanism is through the antioxidant activity of selenoenzymes. However, the effect of selenium intake on selenoenzymes at target tissues is not well established. Hence, we investigated the correlation between serum and prostate tissue selenium concentrations and prostate tissue activity of glutathione peroxidase (GPX), a major selenoenzyme with antioxidant properties. In an ongoing study investigating gene expression in prostate tissue, we measured serum selenium concentration in 98 men using atomic absorption spectrometry. Of these men, we selected 12 men with the highest and 12 men with the lowest serum selenium concentrations and measured selenium concentration and GPX activity in fresh frozen prostate tissue using the cyclic neutron activation analysis and a direct spectrophotometric procedure, respectively. The mean serum selenium concentrations among low and high selenium groups were 123.7 +/- 5.9 and 196.7 +/- 16.6 microg/L (P < 0.0001), respectively. The corresponding mean prostate tissue selenium concentrations were 1.39 +/- 0.28 and 1.65 +/- 0.42 microg/g (P = 0.08), resulting in a positive correlation between serum and prostate tissue selenium concentrations (r = 0.56, P = 0.02). The mean prostate tissue GPX activity was non-significantly greater in the low serum selenium group (32.2 +/- 8.4 U/g protein) than in the high serum selenium group (29.6 +/- 5.9 U/g protein) (P = 0.39) and it was not correlated with serum or prostate tissue selenium concentrations (r = -0.22, P = -0.37 for serum and r = -0.33, P = 0.18 for prostate tissue). Serum and prostate tissue selenium concentrations were moderately correlated. In this population with relatively high selenium concentration, neither prostate tissue nor serum selenium concentrations were associated with prostate tissue GPX activity.