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People living near coal mines have raised concerns on how coal mining affects surrounding communities. Coal mining is a well-documented source of selenium inputs into the environment, and while there is considerable evidence demonstrating adverse effects of excess selenium on reproductive outcomes in fish, selenium toxicity in mammals is less understood. Studies in humans showed a correlation between high levels of selenium and increased adverse pregnancy outcomes, but the mechanisms behind this association are unclear. Importantly, many of the observed adverse pregnancy outcomes associated with high levels of selenium are linked to placental dysfunction. Mechanistically, supraphysiological concentrations of selenium have been shown to cause dysregulation of cortisol and induce ER stress. Balancing the amount of cortisol and ER stress during placental development is important, as a deficiency or surplus of either can cause aberrant placental development and/or placental dysfunction. Given that exposure to excess cortisol has been shown to induce ER stress, and ER stress has been shown to cause aberrant invasion and migration, which are important processes during placental development, the objective of my thesis is to test the hypothesis that excess selenium exposure impacts invasion and migration in first-trimester trophoblasts, and that these effects are mediated by the glucocorticoid and ER stress pathways. HTR-8/SVneo cells (human first-trimester trophoblasts) were exposed to environmentally relevant concentrations of sodium selenite (NaSe) for 24 or 48h. Cortisol was measured via ELISA, migration was measured via a wound-healing assay, and steady-state mRNA expression of genes involved in glucocorticoid homeostasis, ER stress, and invasion, migration, and angiogenesis were measured by qPCR. NaSe treatment caused increased cortisol and induced genes that are indicative of glucocorticoid receptor activation. NaSe also induced genes involved in ER stress as well as the regulation of invasion, migration and angiogenesis. NaSe also decreased migration as measured in the wound healing assay. When cells were co-treated with NaSe and either 1) metyrapone, an inhibitor of the enzyme responsible for synthesizing cortisol (CYP11B1), or 2) mifepristone, an antagonist of glucocorticoid receptor, the genes associated with increased cortisol did not decrease in the cells, suggesting that selenium may be activating the glucocorticoid pathway through alternate means. When the cells were co-treated with NaSe and ER stress inhibitor TUDCA, there was an attenuation of ER stress-related and invasion, migration and angiogenesis-related genes, as well as partial restoration of migration. Selenium treatment appears to have an impact on glucocorticoid activation, ER stress, and migration. While these results do not definitively identify the role that glucocorticoids play in the impact of selenium on migration, the results support the hypothesis that ER stress induced by selenium exposure partially affects migration in first-trimester trophoblasts cells. / Thesis / Master of Science (MSc)

The objectives of this study were to assess growth and reproductive performance of boars fed a diet supplemented with organic selenium (Se). Crossbred boars received one of three treatments: I. basal diet with no supplemental Se, II. basal diet supplemented with 0.3 ppm organic Se (Sel-Plex), and, III. basal diet supplemented with 0.3 ppm sodium selenite. Nursery (n = 13 pens/treatment) boar performance was not affected (P > 0.1) by diet and only grow-finish (n = 11 pens/treatment) G:F was greater (P < 0.06) for Sel-Plex (0.378) compared with selenite (0.368) or control (0.363) boars. At 15-mo of age semen was collected from boars (n = 10/treatment) over 5-d. Semen quality declined over time, but the negative impact day had on sperm motility was less pronounced with Sel-Plex boars. Effects of treatment x day were detected for progressively motile (P = 0.02) and rapidly moving (P = 0.03) spermatozoa, sperm path velocity (VAP; P = 0.05), and average velocity (VSL; P = 0.05). At 17-mo of age, semen was collected from boars (n = 10/treatment), extended and stored over 10-d. Although semen quality decreased over time, sperm from Sel-Plex boars resisted the negative effects of day on sperm motility and pH. Effects of treatment x day were detected for percent motile spermatozoa (P < 0.01), static spermatozoa (P < 0.01), VAP (P = 0.06), amplitude of head displacement (ALH; P = 0.02), straightness (P = 0.01), and pH (P < 0.01). At 23-mo of age, semen was collected (day 0) from boars (n = 6/treatment), extended, stored and evaluated at d 1 and 8 using in vitro fertilization. Dietary Se treatment failed to affect (P < 0.05) in vitro fertilizing rates of boars. In summary, dietary supplementation with Sel-Plex enhanced G:F in grow/finish boars. Dietary Sel-Plex supplementation may decrease the effects that stressors, such as intensive semen collection or semen storage, have on boar sperm characteristics such as sperm motility. The mechanisms for these responses remain to be elucidated. / Ph. D.

Historically, environmental research associated with Appalachian coal surface mines focused on acid mine drainage and reclamation. Recent studies suggest that electrical conductivity (EC) levels above 500 ?S cm-1 can impair Appalachian streams, shifting the focus towards limiting release of total dissolved solids (TDS) and associated elements of concern. Previous column studies utilized an unsaturated bi-weekly leaching design to evaluate the behavior of overburden with respect to TDS, pH, and trace metals. The objective of this study was to determine the effects of column saturation, leaching solution chemistry, and leaching cycle on the release of TDS and associated elements from an unweathered sandstone. Treatments evaluating potential saturation, leaching solution pH, and leaching cycle included saturated, standard method, vacuum, and standpipe fitted columns; simulated acid rain, de-ionized water, and CaCO3 leaching solutions; and 2x week-1, 1x week-1, 2x month-1, and 1x day-1 leaching cycles. Saturation level in the column significantly impacted leachate pH, EC level, and the release of sulfate, bicarbonate, and associated cations by potentially affecting trace sulfide oxidation and carbonate dissolution reactions. Little evidence of saturation was noted with the standard method. Leaching solution bulk chemistry did not alter leachate chemistry. Longer times between dosing cycles corresponded to higher EC, bicarbonate, and associated cation levels, especially over time. Sulfate, Ca, and Se exhibited the greatest percent release based on total mass losses during peak elution. For managing TDS, time between precipitation events and saturation level can strongly affect short and long-term EC level, its major contributors, and elements of concern. / Master of Science

Marine mammals are known for their low susceptibility to mercury toxicity, and it was hypothesized that selenium may play a role in protection against mercury toxicity. To gain insight into the mechanisms of the low susceptibility of cetaceans, we investigated the in vitro effects (1) of mercuric chloride (HgCl₂) on the ultrastructure and cell death of Atlantic spotted dolphin renal cells (Sp1K cells), (2) of HgCl₂ on the cell proliferation and cell cycle status of Sp1K and Rhesus monkey renal cells (MK2), and (3) of sodium selenite (Na₂SeO₃) on cell proliferation and cell death of control and HgCl₂-treated Sp1K cells. HgCl₂ affected multiple organelles and nuclei in Sp1K cells, and induced apoptosis in a time-and dose-dependent manner. Both ultrastructural changes and induction of apoptosis were milder than seen in other cell types in previous publications. In addition, Sp1K cells were able to proliferate at 25 µM HgCl₂ while MK2 cells were killed at 15 µM HgCl₂. An increase in percentage of cells in the G0/G1 phase in the cell cycle and a decrease in S, and G2/M phase cells were seen in Sp1K cells exposed to more than 10 uM HgCl₂ more than 72 hours. MK2 cells showed cell cycle changes only at 24 hours exposure, and may be due to a sensitive subgroup. These data suggested that Sp1K cells were less susceptible than other cell types in a cell-specific way, which was independent of selenium protection. Concurrent exposure to Na₂SeO₃ provided protection against the HgCl₂-induced decrease in cell proliferation of Sp1K. The protective effects were greater if Na₂SeO₃ and HgCl₂ were premixed, but disappeared if exposures did not overlap. Although pretreatments with Na₂SeO₃ alone did not provide protection, they increased the protection of selenium administered later. Furthermore, Na₂SeO₃ decreased HgCl₂-induced apoptosis. These data demonstrated the Na₂SeO₃ protection against HgCl₂ toxicity in Sp1K cells in terms of cell proliferation and apoptosis. This study is the first report that reveals the existence of mercury-selenium antagonism in cultured cetacean cells. The data supported the hypothesis that selenium protection against mercury toxicity is, at least partially, through competition of binding sites and formation of mercury-selenium complex. / Master of Science

Weaning stress in young calves is often compounded with stress from transport, marketing, and commingling. The result is a weakened immune system, which can lead to increased incidence of diseases, especially bovine respiratory disease complex (BRDC). Backgrounding cattle post-weaning and prior to feedlot entry may alleviate some of the more common stresses and typically diminished feed intake. Five trials were conducted with a total of 228 weaned calves to evaluate different backgrounding systems. Drylot diets with 70:30 and 40:60 forage to concentrate total mixed rations with Se and vitamin E injections were studied. No differences were observed in daily gains or feed efficiency among treatments. Steers receiving Se injections had higher (P < 0.05) blood Se concentrations on d 7, 14, 28, and 42. Steers grazed four types of stockpiled pastures with previous pasture treatments: control, poultry litter fed to previous grazing cattle, poultry litter applied, and inorganic fertilizer. Supplements (16% CP) for each pasture treatment were none, soy hulls + SBM (0.5% BW), and corn + SBM (0.5% BW). On d 7, unsupplemented steers had higher (P < 0.05) daily gains than steers supplemented with corn + SBM. No differences were detected on any other day. Heifers grazed stockpiled fescue and were fed three 16% CP supplements: corn gluten feed + soy hulls (0.5% BW), corn gluten feed + soy hulls (1.0% BW), and soy hulls + SBM (0.5% BW). On d 14, heifers supplemented with soy hulls + SBM had higher (P < 0.05) cumulative daily gains. No other differences were detected in gains among treatments. Steers were allotted to four injection treatments: none, Se, vitamin E, and combination of Se and vitamin E. There were no differences in daily gain or blood Se concentrations on any day among all treatments. Steers grazed two pasture types: fescue and fescue + alfalfa, with the following injections: none, vitamin E, and Se. There were no differences in daily gains among all treatments. On d 7, 14, 28, and 42, steers receiving Se injections had higher (P < 0.05) blood Se concentrations. On d 7 and 14, steers grazing fescue pastures had higher serum alpha-tocopherol concentrations than steers grazing fescue + alfalfa pastures. There were no differences in serum alpha-tocopherol concentrations due to injection treatment on any day. No consistent differences were detected in forage and blood serum mineral concentrations in all trials. There were no differences in gains from by-product supplementation versus "traditional" corn-based supplementation, suggesting that by-product feedstuffs may be of value for backgrounding rations. Selenium and vitamin E supplementation did not have any significant effect on calf morbidity. / Master of Science

The effects of weaning stressors on several immune and health responses were measured in three experiments. Sixty-four beef calves from 2 sources were bled on d - 7 (pre-weaning), 0 (weaning), 7, 14, and 21 (post-weaning). Serum selenium (Se), neutrophil and lymphocyte counts, and glutathione peroxidase (GSH-Px) activity for erythrocytes and leukocytes were measured for each calf at each date. Erythrocyte GSH-Px activity remained constant over time, while leukocyte GSH-Px and serum Se increased on d 7 (P<0.0001). Effects of single mineral vs. multi-mineral supplementation were measured for several immune and health responses in 2 trials. Trial 1: 36 heifers weaned on-site at SVAREC were randomly assigned 1 of 2 dietary supplements: 1) no supplement; 2) 15% CP at 0.5% BW; and 1 of 3 injection treatments: 1) no treatment (control); 2) Mu-Se injection; 3) Multi-Min injection. Whole blood Se and serum Cu increased post-weaning and serum Zn decreased post-weaning. Mu-Se-supplemented heifers gained weight faster between d 14-28 vs. Multi-Min-supplemented (P=0.01) or control heifers (P=0.02). Trial 2: 48 steers purchased at auction and transported to SVAREC were randomly assigned to 1 of 4 pasture management systems: 1) control (no treatment); 2) litter fed; 3) litter applied; 4) inorganic fertilizer; and 1 of 3 injection treatments (same as Trial 1). Whole blood Se and serum Cu increased post-stress and serum Zn decreased post-stress. Oxidative burst activity decreased in Mu-Se and Multi-min supplemented steers between d 0-4 vs. control steers (P<0.01). Multi-min-supplemented steers had higher phagocytic activity vs. steers in either Mu-Se or control groups (P=0.04). / Master of Science

Thesis (MScAgric)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: In many parts of the world, soil is depleted of selenium (Se), leading to selenium-poor plants, animals and, therefore, humans. It was recognised that a study to examine the functionality of new products on the market to address this problem was required. The purpose of this research were threefold: to compare the effects of sodium selenite (NaSe) and organically bound selenium sources on small ruminant performance, to investigate the bioavailability of these Se sources, and analyse their influence on carcass characteristics, meat quality and antioxidant capabilities. Fourty growing Döhne Merino wethers from the Southern Cape region, a selenium-deficient area, were used for the study. The animals were all fed the same basal diet in the adaptation period and were then allocated to one of four treatment groups: Control (CT), inorganic selenium (IS), organically bound Se A (OSA) or B: (OSB). The period of supplementation was 90 days. This first study assessed the effect of the different Se sources on growth and Se bioavailability in the wethers. The wethers and the feed they consumed were regularly weighed to determine their growth and feed conversion rate (FCR) in the trial period. To gauge their Se level, blood samples were collected via jugular venipuncture at monthly intervals. The wool around the jugular was shorn and samples were collected on day 0 and day 90 for comparative Se level analysis. Liver, skeletal muscle and kidney samples were collected at day 90, directly after slaughter, to determine the Se level in these tissues. No effect could be reported in the growth and FCR of the wethers between the supplementation groups. For whole blood Se levels there was an effect in the early part of the study, with a greater increase in Se levels for the organically bound Se groups, but in the end no effect on whole blood levels could be seen between the different Se treatments. Neither could any difference between the inorganic Se and organic bound Se treatments be found in the liver – however, the total Se concentration of the wool, kidney and meat samples was greater in those animals offered organically bound Se when compared with those receiving a comparable dose of inorganic Se. The second study evaluated the antioxidant capabilities of the different Se supplements in the wethers. Blood samples were taken monthly for plasma collection to test for Glutathione peroxidase (GSH-Px) activity and total antioxidative capacity (TAC) with the oxygen radical absorbance capacity (ORAC) assay. Liver, skeletal muscle and kidney samples were collected at day 90, immediately after slaughter and measured for GSH-Px activity. With TAC, there was a significant effect for the treatment period between day 0 and day 90, however the treatments did not show any significant difference. No significant differences could be established between the different Se treatments for the GSH-Px analysis in any of the tissues. For the mean plasma values of the treatments no significant differences can be reported, but a significant difference was observed at day 30 in the contrast between the organically bound Se and the other treatment groups. The third study was to evaluate the quality and lipid oxidation of muscle from those wethers supplemented with different Se sources. Skeletal muscle samples were collected at day 90, directly after slaughter to determine this. No differences in the meat quality of the wethers could be detected between Se sources after the 90-day supplementation period. Lipid oxidation was measured by determining TBA reactive substances (TBARS) and once again no differences could be detected. Based on the results found in this investigation, it may be inferred that organically bound Se (OSA & OSB) supplementation will hold a number of advantages for small ruminants over inorganic Se supplementation. Animals fed the organically bound Se had reached adequate Se levels sooner on the organically bounded treatments than the inorganically bounded treated animals. The greater bioavailability of organically bounded Se over inorganic Se was proven by the increased Se levels in certain tissues and organs. Additionally, only the organically bounded Se could find a pathway to the wool, confirming that it was carried in an organic form (probably selenomethionine) in the body. Organically bound Se will therefore have a positive impact on small ruminant health and production, which will result in an indirect advantage for consumer health. / AFRIKAANSE OPSOMMING: Die grond in groot dele van die wêreld word selenium-arm en dit lei na selenium-arm plante, diere en mense. Dit is waargeneem dat ‘n studie wat kyk na die funksionaliteit van nuwe produkte op die mark om die probleem aan te spreek nodig is. Die doelwit van die studie was om verskillende selenium (Se) bronne te vergelyk en die uitwerking daarvan op klein herkouer prestasie te evalueer. Daar is gekyk na die biobeskikbaarheid, invloed daarvan op die karkas eienskappe en antioksidant vermoëns van die verskillende Se bronne. Veertig groeiende Dohne Merino-hamels van die Suid-Kaap-streek, 'n Se arm gebied is gebruik vir die studie. Die diere is almal dieselfde basale dieet gevoer in die aanpassing periode en dan toegeken aan een van vier behandelings: kontrole (CT), anorganiese Se (IS), organies gebinde Se A (OSA) of B: (OSB). Die tydperk van die aanvulling was 90 dae. In die eerste studie is gekyk na die effek van die verskillende bronne van Se op die groei en die biobeskikbaarheid daarvan aan die hamels. Die hamels en voer verbruik, is gereeld geweeg sodat hul groei en voer omset verhouding (VOV) in die proef tydperk te bepaal. Bloedmonsters is versamel deur middel van die jugulêre venipuncture vir die Se vlak bepaling daarvan. Lewer, skeletspier en nier monsters is versamel op dag 90, direk na die slagting vir die Se vlak bepaling. Die wol rondom die nekslagaar is geskeer en monsters is versamel op dag 0 en 90 vir Se vlak analise. Geen effek kan gerapporteer word vir die groei en VOV van die hamels tydens die aanvullings periode nie. Vir die bloed Se vlakke was daar 'n uitwerking in die vroeë deel van die studie, met 'n vinniger toename in Se vlakke vir die organies gebinde Se groepe, maar aan die einde kon geen effek gesien word tussen die verskillende Se behandelings nie. Geen verskil tussen die NaSe en organiese gebonde Se behandelings kon gevind word in die lewer nie. Die totale Se konsentrasie van die wol-, nier-en vleis

Twenty-one women, lifelong residents of Xichang County, Sichuan Province, China, an area of very low soil selenium (Se), received tablets containing either 100 μg Se daily as Se-enriched yeast (+Se) or no additional Se (-Se), throughout the last trimester of pregnancy and the first three months of lactation. Diet was analyzed using diet recalls and proximate analysis of mixed diet samples. Milk and plasma samples were analyzed for Se content, glutathione peroxidase activity, and fatty acid profile and plasma alone was analyzed for vitamin E content and lipid peroxidation. At parturition and three months after delivery, milk and plasma Se levels and plasma GPx activities were significantly higher in the +Se women than the -Se women. Milk GPx activity did not change significantly with supplementation. Plasma vitamin E was not different between the treatment groups at either time. Plasma lipid peroxidation levels (TBARS) were significantly higher in the supplemented women at both time points. Fatty acid profiles at delivery and three months after delivery were similar in both plasma and milk between the two groups. The data suggest that this level and length of supplementation, when given to pregnant women of very low Se status, are not adequate to influence the fatty acids in milk. / Graduation date: 2000