Tissue Se Research Articles

Selenocompounds in juvenile white sturgeon: Evaluating blood, tissue, and urine selenium concentrations after a single oral dose

Selenium (Se) is an essential micronutrient for all vertebrates, however, at environmental relevant levels, it is a potent toxin. In the San Francisco Bay-Delta, white sturgeon, an ancient Chondrostean fish of high ecological and economic value, is at risk to Se exposure. The present study is the first to examine the uptake, distribution, and excretion of various selenocompounds in white sturgeon. A combined technique of stomach intubation, dorsal aorta cannulation, and urinary catheterization was utilized, in this study, to characterize the short-term effects of Se in the forms of sodium-selenate (Selenate), sodium-selenite (Selenite), selenocystine (SeCys), l-selenomethionine (SeMet), Se-methylseleno-l-cysteine (MSeCys), and selenoyeast (SeYeast). An ecologically relevant dose of Se (∼500μg/kg body weight) was intubated into groups of 5 juvenile white sturgeon. Blood and urine samples were repeatedly collected over the 48h post intubation period and fish were sacrificed for Se tissue concentration and distribution at 48h. The tissue concentration and distribution, blood concentrations, and urinary elimination of Se significantly differ (p≤0.05) among forms. In general, organic selenocompounds maintain higher blood concentrations, with SeMeCys maintaining the highest area under the curve (66.3±8.7 and 9.3±1.0μgh/ml) and maximum Se concentration in blood (2.3±0.2 and 0.4±0.2μg/ml) in both the protein and non-protein bound fractions, respectively. Selenate, however, did not result in significant increase of Se concentration, compared with the control, in the protein-bound blood fraction. Regardless of source, Se is preferentially distributed into metabolically active tissues, with the SeMet treated fish achieving the highest concentration in most tissues. In contrast, Selenite has very similar blood concentrations and tissue distribution profile to SeCys and SeYeast. From blood and tissue Se concentrations, Selenate is not stored in blood, but taken up rapidly by the liver and white muscle. Urinary elimination of Se is form dependent and peaks between 3 and 12h post intubation. A basic understanding of the overall Se absorption, distribution, and elimination is provided through monitoring tissue Se concentrations, however, conclusions regarding to the dynamics and the specific processes of Se metabolism can only be inferred, in the absence of kinetic information.

Selenoprotein W depletion induces a p53‐ and p21‐dependent delay in cell cycle progression in RWPE‐1 prostate epithelial cells

The anticancer activity of selenium (Se) has been demonstrated in myriad animal and in vitro studies, yet the mechanisms remain obscure. The main form of Se in animal tissues is selenocysteine in selenoproteins, but the relative importance of selenoproteins versus smaller Se compounds in cancer protection is unresolved. Selenoprotein W (SEPW1) is a highly conserved protein ubiquitously expressed in animals, bacteria, and archaea. SEPW1 depletion causes a delay in cell cycle progression at the G1/S transition of the cell cycle in breast and prostate epithelial cells. Tumor suppressor protein p53 is a master regulator of cell cycle progression and is the most frequently mutated gene in human cancers. p53 was increased in SEPW1 silenced cells and was inversely correlated with SEPW1 mRNA in cell lines with altered SEPW1 expression. Silencing SEPW1 decreased ubiquitination of p53 and increased p53 half-life. SEPW1 silencing increased p21(Cip1/WAF1/CDKN1A), while p27 (Kip1/CDKN1B) levels were unaffected. G1-phase arrest from SEPW1 knockdown was abolished by silencing p53 or p21. Cell cycle arrest from SEPW1 silencing was not associated with activation of ATM or phosphorylation of Ser-15 in p53, suggesting the DNA damage response pathway was not involved. Silencing GPX1 had no effect on cell cycle, suggesting that G1-phase arrest from SEPW1 silencing was not due to loss of antioxidant protection. More research is required to identify the function of SEPW1 and how it affects stability of p53.

Ecological aspects of plant selenium hyperaccumulation

Hyperaccumulators are plants that accumulate toxic elements to extraordinary levels. Selenium (Se) hyperaccumulators can contain 0.1-1.5% of their dry weight as Se, levels toxic to most other organisms. In this review we summarise what is known about the ecological functions and implications of Se (hyper)accumulation by plants. Selenium promotes hyperaccumulator growth and also offers a plant several ecological advantages through negative effects on Se-sensitive partners. High tissue Se levels reduce herbivory and pathogen infection, and high-Se litter deposition can inhibit neighbouring plants. There is no evidence for a cost of hyperaccumulation in terms of reproductive functions or pollinator visitation. Hyperaccumulators offer a niche for Se-tolerant herbivores, pollinators, microbes and neighbouring plants. They may even facilitate these partners through Se enrichment: neighbouring plants with elevated Se levels enjoy enhanced growth and reduced herbivory. Through combined negative and positive effects on ecological partners, Se hyperaccumulators likely affect local plant, microbial and animal species composition and richness, favouring Se-tolerant species at different trophic levels. By locally concentrating Se and altering its chemical form, Se hyperaccumulators likely play an important role in Se entry into, and Se cycling through, seleniferous ecosystems. These findings are of significance since they provide insight into the ecological reverberations of Se hyperaccumulation, and shed light on the possible selection pressures that have led to the evolution of this fascinating phenomenon. Better ecological insight will also help in the management of seleniferous areas and the agricultural production of Se-rich crops for phytoremediation or biofortification.

Mercury exposure and mechanism of response in large game using the Almadén mercury mining area (Spain) as a case study

Mercury (Hg) accumulation, transfer, defense mechanism and adverse effects were studied in red deer (Cervus elaphus) and wild boar (Sus scrofa) from the Almadén mining district (Spain), the largest (285,000t of Hg) and the oldest (more than 2000 years) Hg mine/refining operation site in the world. Red deer (n=168) and wild boar (n=58) liver, kidney, bones (metacarpus), testis and muscle were analyzed for total Hg and selenium (Se) within a range of distances to the Almadén mining district. The highest Hg concentrations were found in kidney (0.092 and 0.103μg/g d.w. for red deer and wild boar, respectively) followed by the levels in liver (0.013 and 0.023μg/g d.w. for red deer and wild boar, respectively). A significant correlation (r=−0.609, p=0.007) was found between Hg concentrations and distance to the Almadén Hg mining district. However, both red deer and wild boar closest to the mining area still showed mercury concentrations well below the concentration associated with clinical signs of Hg poisoning. Highest Se concentrations were found in kidney (2.60 and 6.08μg/g in red deer and wild boar, respectively) and testis (2.20μg/g in red deer). For selenium, differences between red deer and wild boar were statistically significant (p<0.05) in all tissues, concentrations being higher in wild boar than in red deer. In the diagnosis of Se deficiency, the vast majority of the examined red deer livers were deficient. A significant correlation was found between Hg and Se in kidney (r=0.386, p>0.001 for red deer and r=0.567, p=0.005 for wild boar). Liver GSSG concentrations were negatively correlated to total mercury and Hg:Se molar ratio in male deer, which could indicate a hormetic response to Hg exposure. Moreover, a positive association was found between the antioxidant element Se and antioxidant vitamins in red deer tissues.

Trace elements of normal, benign hypertrophic and cancerous tissues of the Human prostate gland investigated by neutron activation analysis

The Ag, Co, Cr, Fe, Hg, Rb, Sb, Sc, Se, and Zn contents in normal (n=37), benign hypertrophic (n=43), and cancerous tissues (n=60) of the human prostate gland were investigated by neutron activation analysis. Mean values (M±SΕΜ) for content (mg/kg, dry weight basis) of trace elements in the normal tissue were: Ag-0.048±0.009, Co-0.045±0.004, Cr-0.53±0.08, Fe-111±9, Hg-0.056±0.011, Rb-12.7±0.9, Sb-0.045±0.007, Sc-0.029±0.005, Se-0.70±0.04, and Zn-1000±110, respectively. It was observed that in benign hypertrophic tissues the contents of Co, Cr, Hg, Sb, and Se were higher than in normal tissues, with statistically significant differences. The contents of Co, Rb, Sc, and Zn were significantly lower and those of Ag, Cr, Fe, Hg, and Sb were significantly higher in cancerous tissues than in normal tissues.

Selenium Regulates Gene Expression of Selenoprotein W in Chicken Gastrointestinal Tract

Selenoprotein W (SelW) is an existing form of selenium (Se). Se influences the levels of SelW in mammals. However, little is known about the pattern of SelW expression in the gastrointestinal tract tissue of bird. The present paper describes the effects of different dietary levels of Se on the SelW mRNA expression in the gastrointestinal tract tissue of chicken. The expression levels of SelW mRNA and the Se contents in the gastrointestinal tract tissues (glandular stomach, gizzard, duodenum, small intestine, and rectum) were determined on days 15, 25, 35, 45, and 55, respectively. The results showed that the Se contents and the SelW mRNA expression were significantly higher (p < 0.05) in the high-Se group, and the Se contents and SelW mRNA expression in the low-Se group were significantly lower (p < 0.05) than in the controls. The Se contents were the highest in the duodenum and the lowest in the rectum, while the SelW mRNA expression was the highest in the gizzard and the lowest in the rectum. In addition, the SelW mRNA levels in the gastrointestinal tract tissue were found to increase in a time-dependent manner with increasing feeding time. Furthermore, the expression of the SelW mRNA in the gastrointestinal tract tissues of chickens was found to correlate with the dietary Se concentrations, but not with the tissue Se contents.

Association of Pb, Cd, and Se Concentrations and Oxidative Damage-Related Markers in Different Grades of Prostate Carcinoma

Prostate cancer is known to be affected by the heavy metal levels and oxidative damage of the body, yet there are very few studies which look into the way it occurs. The aim of this study was to determine whether blood and tissue lead (Pb), cadmium (Cd), and selenium (Se) levels are associated with oxidative damage in the context of prostate cancer progression and development. Seventy-nine patients comprising 25 patients with benign prostatic hypertrophy (BPH), 23 patients with malignant prostatic carcinoma (malign Ca), 16 patients with low-grade prostatic intraepithelial neoplasia (LGPIN), and 15 patients with high-grade prostatic intraepithelial neoplasia (HGPIN) diagnosed on the basis of their clinical profile, transrectal ultrasonography, and histopathology were included in this study. Cd and Pb levels in whole blood were found to be increased in patients with HGPIN compared with the BPH group; also, the levels of Cd in whole blood and tissue were found to be increasing in patients with malign Ca, unlike BPH patients. Moreover, the levels of malondialdehyde (MDA) in plasma and tissue were significantly increased in malign Ca, LGPIN, and HGPIN than those in BPH. However, the levels of tissue Pb were found to be decreasing in BPH, unlike the malign Ca and HGPIN patients, and the levels of tissue protein carbonyls in malign Ca were significantly lower than those in HGPIN. The levels of tissue reduced glutathione (GSH) in malign Ca were significantly lower than those in BPH. Additionally, the levels of Se in serum and tissue in LGPIN were significantly lower than those in BPH. The serum Se levels in HGPIN were also significantly lower than those in BPH and malign Ca groups. Furthermore, the concentrations of serum Se in LGPIN were significantly lower than those in malign Ca. From the Pearson correlation analysis, there were significant positive correlations between tissue Cd and MDA levels in malign Ca, LGPIN, and HGPIN and between the tissue Pb and tissue MDA and protein carbonyl levels in malign Ca. Blood Pb and tissue Pb were also significantly positively correlated with plasma MDA and protein carbonyl levels in malign Ca. In addition, blood Pb was significantly positively correlated with tissue MDA and protein carbonyl levels in malign Ca, and a significant positive correlation was also found between blood Cd and plasma protein carbonyls and tissue MDA in LGPIN. We observed that altered prooxidant-antioxidant balance and heavy metal levels may lead to an increase in oxidative damage and may consequently play an important role in prostate carcinogenesis. These findings indicate that changes in the levels of Pb, Cd, Se, MDA, protein carbonyls, and GSH in the blood and/or tissue are related to the prostatic carcinoma development and progression, although triggering one of the mentioned changes is unknown; therefore, further study is required to determine the exact steps of the process and clarify the roles of different substances in order to obtain a more detailed explanation of the phenomenon.

Dietary Selenomethionine Increases Exon-Specific DNA Methylation of the p53 Gene in Rat Liver and Colon Mucosa ,

The regulation of site-specific DNA methylation of tumor suppressor genes has been considered as a leading mechanism by which certain nutrients exert their anticancer property. This study was to investigate whether selenium (Se) affects the methylation of globe genomic DNA and the exon-specific p53 gene. Three groups of rats ( n = 6–7/group) were fed the AIN-93G basal diet supplemented with 0 [Se deficient (D)], 0.15 [Se adequate (A)], or 4 mg [Se supranutritional (S)] (Se as L-selenomethionine)/kg diet for 104 d, respectively. Rats fed the A or S diet had greater plasma and liver glutathione peroxidase activity, liver thioredoxin reductase activity, and plasma homocysteine concentration than those fed the D diet. However, compared with the A diet, rats fed the S diet did not further increase these Se-dependent enzyme activities or homocysteine concentration. In contrast, Se concentrations in kidney, liver, gastrocnemius muscle, and plasma were increased in a Se-dose–dependent manner. Interestingly, rats fed the S diet had significantly less global liver genomic DNA methylation than those fed the D diet. However, the S diet significantly increased the methylation of the p53 gene (exons 5–8) but not the β-actin gene (exons 2–3) DNA in liver and colon mucosa compared with those fed the D diet. Taken together, long-term Se consumption not only affects selenoprotein enzyme activities, homocysteine, tissue Se concentrations, and global genomic DNA methylation but also increases exon-specific DNA methylation of the p53 gene in a Se-dose–dependent manner in rat liver and colon mucosa.

Effects of selenomethionine and sodium selenite supplementation on meat quality, selenium distribution and antioxidant status in broilers

This study was conducted to investigate the effects of selenomethionine (Se-Met) and sodium selenite (SS) supplementation on meat quality, selenium (Se) distribution, and antioxidant status in broilers. A total of 360 seven-days-old Ross 308 broilers of an average body weight 162 &amp;plusmn; 0.59 g were randomly allotted to three treatments, each of which included three replications of 40 birds. The treatments included a control diet containing 0.04 mg Se/kg and other two diets that contained 0.15 mg Se/kg supplemented by SS or Se-Met. The experiment lasted for 42 days. Selenium supplementation improved (P &amp;lt; 0.05) the Hunter a value of breast muscle in 8 and 16 h and decreased (P &amp;lt; 0.05) the drip loss of breast muscle in 24 and 48 h. Both Se sources and exposed time significantly influenced (P &amp;lt; 0.01) the drip loss of breast muscle. Selenium and glutathione concentrations in serum and in the studied organs were significantly higher (P &amp;lt; 0.05) after dietary Se supplementation while the Se-Met group showed the highest value (P &amp;lt; 0.05). Glutathione peroxidase activity in serum and in the studied organs was also significantly elevated (P &amp;lt; 0.05) by dietary Se supplementation while SS increased the glutathione peroxidase activities in pancreas and breast muscle to a larger extent (P &amp;lt; 0.05) than did Se-Met. The addition of Se from either source caused a significant increase (P &amp;lt; 0.05) in superoxide dismutase activities in tissues (except for kidney) whereas the Se-Met group was more effective (P &amp;lt; 0.05) than the SS group in breast muscle. Selenium supplementation increased (P &amp;lt; 0.05) the total antioxidant capability in serum, liver, kidney and breast muscle while the Se-Met group proved to be more effective (P &amp;lt; 0.05) than the SS group except for kidney. The Se-supplemented diets had a lower (P &amp;lt; 0.05) malondialdehyde concentration in serum and in the studied organs but the effect was more pronounced (P &amp;lt; 0.05) when Se-Met was used except for the serum. These results indicated that Se-Met supplementation was more effective than SS supplementation for depositing Se in serum and tissues, enhancing the antioxidant status and reducing the drip loss of breast muscle.

Selenium Moderates Mercury Toxicity in Free-Ranging Freshwater Fish.

Due to the extremely high affinity of selenium (Se) to mercury (Hg), Se sequesters Hg and reduces its biological availability in organisms. However the converse is also true. Hg sequesters Se, causing Hg to inhibit the formation of Se dependent enzymes while supplemental Se supports their continued synthesis. Hence, whether or not toxic effects accompany exposure to Hg depends upon the tissue Se:Hg molar ratio of the organism. The main objective of the present study was to investigate how levels of Hg and Se affected metallothionein (MT) induction in free-ranging brown trout, Salmo trutta, from Lake Mjøsa, Norway (a Se depauperate lake). MT is proposed as a sensitive biomarker of potential detrimental effects induced by metals such as Hg. Emphasis was addressed to elucidate if increased tissue Se:Hg molar ratios and Se levels affected the demands for MT in the trout. The Se:Hg molar ratio followed by tissue Se levels were most successful for assessing the relationship between metal exposure and MT levels in the trout. Thus, Hg in molar excess over Se was a stronger inducer of MT synthesis than tissue Hg levels in the trout, supporting the assumption that Se has a prominent protective effect against Hg toxicity. Measuring Hg in animals may therefore provide an inadequate reflection of the potential health risks to humans and wildlife if the protective effects of Se are not considered.

Food rationing affects dietary selenium bioaccumulation and life cycle performance in the mayfly Centroptilum triangulifer

Selenium effects in nature are mediated by the relatively large bioconcentration of aqueous Se by primary producers and smaller, yet critical, dietary transfers to primary consumers. These basal processes are then propagated through food webs to higher trophic levels. Here we quantified the movement of dissolved Se (as selenite) to periphyton, and used the resultant periphyton as a food source for conducting full life-cycle dietary Se exposures to the mayfly Centroptilum triangulifer. Periphyton bioconcentrated Se ~2,200-fold from solution in a log-linear fashion over dissolved Se concentrations ranging from 1.1 to 23.1 μg L(-1). We examined the influence of two feeding ration levels (1x and 2x) on trophic transfer, tissue Se concentrations, maternal transfer, and functional endpoints of mayfly performance. Mayflies fed a lesser ration (1x) displayed greater trophic transfer factors (mean TTF, 2.8 ± 0.4) than mayflies fed 2x rations (mean TTF, 1.1 ± 0.3). In 1x exposures, mayflies exhibited significant (p < 0.05) reductions in survivorship and total body mass at dietary [Se] ≥ 11.9 μg g(-1), reduced total fecundity at ≥ 4.2 μg g(-1), and delayed development at ≥ 27.2 μg g(-1). Mayflies fed a greater ration (2x) displayed reduced tissue Se concentrations (apparently via growth dilution) relative to 1x mayflies, with no significant effects on performance. These results suggest that the influence of Se on mayfly performance in nature may be tied to food resource availability and quality. Furthermore, nutritional status is an important consideration when applying laboratory derived estimates of toxicity to risk assessments for wild populations.

Responses of Growing Japanese Quails that Received Selenium from Selenium Enriched Kale Sprout (Brassica oleracea var. alboglabra L.)

The objectives of this study were to determine the effect of selenium (Se) from Se-enriched kale sprout (Brassica oleracea var. alboglabra L.) on the performance and Se concentrations in tissues of growing Japanese quails. Two hundred quails were divided into five treatments. Each treatment consisted of four replicates and each replicate contained ten quails in a completely randomize design. The experiment was conducted for 5weeks. The treatments were T1, control diet; T2, control diet plus 0.2mg Se/kg from sodium selenite; T3, T4, and T5, control diet plus 0.2, 0.5, and 1.0mg Se/kg from Se-enriched kale sprout. The results revealed that Se supplementation had no impact on feed intake, performance, and carcass characteristics of quails (p > 0.05). However, Se supplementation from both sodium selenite and Se-enriched kale sprout increased (p < 0.05) Se concentrations in the heart and breast meat of quails. Se concentrations in the liver and breast meat of quails increased (p < 0.05) with increasing Se concentration from Se-enriched kale sprout. The results indicate that Se from Se-enriched kale sprout offers no advantage over Se from sodium selenite on tissue Se concentration.

Selenium bioavailability from naturally produced high-selenium peas and oats in selenium-deficient rats.

This study determined the bioavailability of selenium (Se) from yellow peas and oats harvested from the high-Se soil of South Dakota, United States. The Se concentrations were 13.5 ± 0.2 and 2.5 ± 0.1 mg/kg (dry weight) for peas and oats, respectively. Male weanling Sprague-Dawley rats were depleted of Se by feeding them a 30% Torula yeast-based diet (4.1 μg Se/kg) for 56 days, and then they were replenished with Se for an additional 50 days by feeding them the same diet supplemented with 20, 30, or 40 μg Se/kg from peas or oats, respectively. Selenium bioavailability was determined on the basis of the restoration of Se-dependent enzyme activities and tissue Se concentrations in Se-depleted rats, comparing those responses for yellow peas and oats to those for l-selenomethionine (SeMet; used as a reference) by using a slope-ratio method. Dietary supplementation with peas or oats resulted in linear or log-linear, dose-dependent increases in glutathione peroxidase activities in blood and liver and in thioredoxin reductase activity in liver. Supplementation with peas or oats resulted in linear or log-linear, dose-dependent increases in Se concentrations of plasma, liver, gastrocnemius muscle, and kidneys. The overall bioavailability was approximately 88% for Se from yellow peas and 92% from oats, compared to SeMet. It was concluded that Se from naturally produced high-Se yellow peas or oats is highly bioavailable in this model and that these high-Se foods may be a good dietary source of Se.

Assessing the adaptability of the actinorhizal symbiosis in the face of environmental change

Human activity, and in particular industrial activity, has altered natural environments. Here we present an experimental approach adapted to study the actinorhizal symbiosis in alder trees and shrubs submitted to abiotic stress. We measured the impact of exogenous nitrogen on the establishment of the alder symbiosis with Frankia sp., and its primary function; nitrogen fixation. Results showed our version of the growth pouch method was functional, and corroborated the gradual inhibition of symbiosis in the presence of increasing exogenous nitrogen concentrations. In mountain alder ( Alnus viridis ssp. crispa) there was a gradual and suppressive effect of nitrogen on the relative number or root nodules, while in black alder ( Alnus glutinosa) results suggested a threshold effect at 45 ppm N. Shoot to root biomass ratios were increased in the presence of the microsymbiont, and this effect was generally maintained even in the presence of heavy metals (As, Se or V). Alders and the actinorhizal symbiosis were not heavily affected by the presence of heavy metals, confirming potential applications in soil rehabilitation, however the distribution of metals in plant tissues sometimes changed when high levels of metals were present. A. glutinosa plants exposed to high levels of As significantly increased the allocation of As to roots (≈90%), while those exposed to high levels of Se rose their aerial tissue Se allocation to roughly 86%. A. glutinosa plants exposed to high V levels did not change behavior: V was in all cases preferentially accumulated in underground tissues (≥90%). Our results detail the use of a high-throughput approach to study the plasticity of the actinorhizal symbiosis in the presence of fluctuating nitrogen and metal conditions. These methods are transposable to numerous actinorhizal studies in both fundamental and applied research.

Predictive modeling of selenium accumulation in brine shrimp in saline environments

Great Salt Lake, Utah, is a large, terminal, hypersaline lake consisting of a northern more saline arm and a southern arm that is less saline. The southern arm supports a seasonally abundant fauna of low diversity consisting of brine shrimp (Artemia franciscana), 7 species of brine flies, and multiple species of algae. Although fish cannot survive in the main body of the lake, the lake is highly productive, and brine shrimp and brine fly populations support large numbers of migratory waterfowl and shorebirds, as well as resident waterfowl, shorebirds, and gulls. Selenium and other trace elements, metals, and nutrients are contaminants of concern for the lake because of their concentrations in municipal and industrial outfalls and runoff from local agriculture and the large urban area of Salt Lake City. As a consequence, the State of Utah recently recommended water quality standards for Se for the southern arm of Great Salt Lake based on exposure and risk to birds. The tissue-based recommendations (as measured in bird eggs) were based on the understanding that Se toxicity is predominately expressed through dietary exposure, and that the breeding shorebirds, waterfowl, and gulls of the lake are the receptors of most concern. The bird egg-based recommended standards for Se require a model to link bird egg Se concentrations to their dietary concentrations and water column values. This study analyzes available brine shrimp tissue Se data from a variety of sources, along with waterborne and water particulate (potential brine shrimp diet) Se concentrations, in an attempt to develop a model to predict brine shrimp Se concentrations from the Se concentrations in surrounding water. The model can serve as a tool for linking the tissue-based water quality standards of a key dietary item to waterborne concentrations. The results were compared to other laboratory and field-based models to predict brine shrimp tissue Se concentrations from ambient water and their diet. No significant relationships were found between brine shrimp and their dietary Se, as measured by seston concentrations. The final linear and piecewise regression models showed significant positive relationships between waterborne and brine shrimp tissue Se concentrations but with a very weak predictive ability for waterborne concentrations<10 µg/L.

Effects of organic and inorganic dietary selenium supplementation on gene expression profiles in oviduct tissue from broiler-breeder hens

Selenium (Se) is an essential component of at least 25 selenoproteins involved in a multitude of physiological functions, including reproduction. However, relatively little is known about the mechanisms by which Se exerts its physiological effects in reproductive tissue. The objective of this study was to compare the effect of long-term inorganic Se (sodium selenite, SS) and organic yeast-derived Se (Sel-Plex ®, SP) supplementations on tissue Se content and gene expression patterns in the oviduct of broiler-breeder hens. Hens were randomly assigned at 6 weeks of age to one of the three treatments: basal semi-purified diet (control), basal diet + 0.3 ppm Se as SP or basal diet + 0.3 ppm Se as SS. At 49 weeks, oviduct tissue from hens randomly selected from each treatment ( n = 7) was analyzed for Se content and gene expression profiles using the Affymetrix Chicken genome array. Gene expression data were evaluated using GeneSpring GX 10.0 (Silicon Genetics, Redwood, CA) and Ingenuity Pathways Analysis software (Ingenuity Systems, Redwood City, CA). Oviduct Se concentration was greater with Se supplementation compared with the control ( P ≤ 0.05) but did not differ between SS- and SP-supplemented groups. Gene expression analysis revealed that the quantity of gene transcripts associated with energy production and protein translation were greater in the oviduct with SP but not SS supplementation. Targets up-regulated by SP, but not SS, included genes encoding several subunits of the mitochondrial respiratory complexes, ubiquinone production and ribosomal subunits. SS hens showed a decrease in transcripts of genes involved in respiratory complexes, ATP synthesis and protein translation and metabolism in oviduct relative to control hens. In this study, although tissue Se concentrations did not differ between hens fed SS- and SP-supplemented diets, expression patterns of genes involved in energy production and protein synthesis pathways differed between treatments. These variations may partially explain the differences in reproductive performance reported in hens fed different forms of Se.

Influence of dietary nano elemental selenium on growth performance, tissue selenium distribution, meat quality, and glutathione peroxidase activity in Guangxi Yellow chicken

This experiment was designed to investigate the effect of feed supplementation with nano elemental Se (Nano-Se) on growth performance, tissue Se distribution, meat quality, and glutathione peroxidase (GSH-Px) activity in Guangxi Yellow chicken. Four treatments (control, T-1, T-2, and T-3 treatment groups) with 3 replicates of 30 chickens each were carried out. Diets for the control, T-1, T-2, and T-3 groups consisted of the basal diet supplemented with, respectively, 0.00, 0.10, 0.30, and 0.50 mg/kg of Nano-Se. Improved final BW, daily BW gain (DWG), feed conversion ratios, and survival rate (P < 0.05) were observed in the groups supplemented with Nano-Se as compared with the control groups after 90 d of feeding. The groups that received Nano-Se showed higher (P < 0.05) hepatic and muscle Se contents, drip loss percentage, inosine 5'-monophosphate content, and GSH-Px activities in the serum and liver than that did the control groups. For the T-2 and T-3 groups, a significant difference (P < 0.05) was observed in final BW, DWG, muscle Se content, breast drip loss, and GSH-Px activities in the serum and liver compared with the T-1 group. However, no significant differences were observed in final BW, DWG, and GSH-Px activities in the serum and liver between the T-2 and T-3 groups. It could be concluded from this study that supplementing diets with 0.30 mg/kg of Nano-Se for was effective in increasing the growth performance and feed conversion ratios of chickens, the Se content of tissues, and the quality of the meat.

Efficacy of feeding selenium-enriched yeast to finishing beef cattle

<h2>ABSTRACT</h2> An experiment was conducted to evaluate supplementation with Se yeast of a finishing diet containing adequate Se from feedstuffs. Forty calves (307 ± 3.2 kg) were blocked by sex and randomly allotted to 8 pens. After completing acclimation to the diet, pens were randomly assigned within sex to the basal finishing diet (CON) or the basal finishing diet plus 0.34 mg of supplemental Se per kilogram of dietary DM from Se yeast (SUP) for a 130-d finishing period. Body weight and blood samples were obtained at 28-d intervals and before shipping. At slaughter, hot carcass weights were recorded and liver samples collected. After a 48-h chill, standard carcass data and LM samples were obtained. No differences (P > 0.10) in BW, ADG, DMI, feed efficiency, or any carcass measures were detected. Serum Se had a treatment-bytime interaction (P < 0.01) where initial serum Se concentrations were similar, but subsequently SUP calves had greater (P < 0.01) serum Se concentrations than did CON calves. Muscle and liver Se concentrations were lower (P < 0.01) for CON than for SUP calves. There was a treatment-by-sex interaction (P < 0.01), with heifers on SUP having higher liver Se concentrations than those of SUP steers. Results of this experiment indicate that supplementing 0.34 mg/kg Se (DM) from Se yeast to a basal feedlot diet with adequate Se does not increase performance but does result in increased tissue Se concentrations that do not exceed a range determined as normal.

Accumulation and Speciation of Selenium in Plants as Affected by Arbuscular Mycorrhizal Fungus Glomus mosseae

Effects of arbuscular mycorrhizal fungus (Glomus mosseae) on the accumulation and speciation of selenium (Se) in alfalfa, maize, and soybean were investigated by using Se(IV)-spiked soil. Mycorrhizal inoculation decreased Se accumulation in roots and shoots of all the plants at Se spiked level of 0 or 2mgkg(-1), while an increased Se accumulation was observed in alfalfa shoots and maize roots and shoots at the spiked level of 20mgkg(-1). Concentration of inorganic Se (especially Se(VI)) in roots and shoots of the three plants was much higher in mycorrhizal than non-mycorrhizal treatment. Mycorrhizal inoculation decreased the portion of total organic Se in plant tissues with the exception of alfalfa and maize shoots at Se spiked level of 20mgkg(-1), in which organic Se portion did not reduced greatly (<5%) for mycorrhizal treatment. Mycorrhizal effects on alfalfa and maize were more obvious than on soybean in terms of root colonization rate, biomass, and Se accumulation.

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.