Quarter Horse mares (n=28, 465-612 kg BW, 6-19 yrs of age) were used to investigate the effect of organic selenium (Se) supplementation (Selenosource, Diamond V Mills, Inc. Cedar Rapids, IA (SeM)) and DE manipulation on plasma, muscle, and colostrum Se concentrations, plasma glutathione peroxidase (Gsh-Px) activity, foaling parameters, and physical characteristics in mares and their foals. Mares were arranged in a 2x2 factorial with two levels of nutrition, pasture (100% NRC DE) or pasture plus grain (120% NRC DE) (fed at 0.75% BW (0.63 ppm Se)) and two levels of Se supplementation (0 or 0.3 mg/kg DM) equaling four treatment groups: pasture (P), pasture grain (PG), pasture grain Se (PGS), or pasture Se (PS). Mares were blocked by expected foaling date and randomly assigned to dietary treatment within block. Body condition score (BCS), BW, and rump fat (RF) were observed every 14 d beginning at d 0. Mare and foal plasma and muscle sampling began on d 0 (birth in foals). Plasma continued every 14 d and muscle every 28 d until parturition (d 56 in foals). Upon parturition, foaling parameters consisting of times: water break to birth, birth to placenta expulsion, foal standing, and nursing were recorded. Colostrum quality was determined via refractometer and colostrometer analysis, and placenta weight, foal birth weight, whither and hip height and body length were recorded. Maternal SeM supplementation influenced (P<0.05) mare and foal plasma, muscle and colostrum Se concentrations. Increased maternal DE influenced (P<0.05) mare and foal plasma and foal muscle Se, mare BW, BCS, and RF. However, mare muscle Se was unaffected (P>0.05) by DE. Mare and foal plasma Gsh-Px, foal physical characteristics, and foaling parameters were unaffected by treatment (P>0.05). Greater (P<0.02) colostrum refractometer values (Brix%) for P, PS mares were noted and PGS, P mares had shorter gestational lengths (nutrition x SeM interaction (P<0.05)). These data indicate that maternal DE manipulation and SeM supplementation influences mare and foal Se status, mare BW and colostrum quality (Brix%), but not plasma Gsh-Px activity. Additionally, nutrition and SeM supplementation may affect gestational length. However, despite treatments there was no difference in foaling parameters or foal physical characteristics.

The chemistry of the enzyme glutathione peroxidase and synthetic organoselenium enzyme mimics has been a significant research interest for more than three decades. In this work, the results of a computational study employing modern electronic structure methods to model the reactions of a synthetic glutathione peroxidase mimic are presented. The ability of nine density-functional theory methods and thirteen basis sets to predict both molecular geometries and bond dissociation energies in organoselenium compounds is examined. This is used to determine the best methodology to employ for the study of glutathione peroxidase mimics. The key reactions in the catalytic mechanism of the organoselenium antioxidant N,N-dimethyl-benzylamine-2-selenol are the focus of the remainder of the document. This is a three-step mechanism which includes many of the organic forms adopted by selenium compounds, including selenol, oxoacids, and selenylsulfides. In the first step of the cycle, the well-studied reduction of hydrogen peroxide by a selenol and a diselenide is modelled. The second step modelled is a substitution reaction at the selenium centre of a selenenic acid with a thiol. The final step discussed is the reduction of the selenium centre in a selenylsulfide, regenerating the selenol and forming a disulfide species. Each mechanism is evaluated by discussing both molecular geometries and reaction energetics. To close the document, the peroxide reduction reaction is revisited to determine the effects of substitution on the phenyl ring of the synthetic antioxidant. This serves as a preliminary attempt to improve the antioxidant efficiency of this compound. In addition to a discussion of the changes in reaction energetics predicted, the topology of the electron density is studied using the quantum theory of atoms in molecules to better understand how the distribution of electron density is affected by substituents.

Lo, Yun Chuen. / Thesis (M.Sc.)--Chinese University of Hong Kong, 1992. / Includes bibliographical references (leaves 69-70). / Summary --- p.1 / Introduction --- p.2 / Methods --- p.6-15 / Subjects / Sample treatment / Protocol / "Equipment, reagents and assays" / Results --- p.15-58 / Technical aspects / Assay characteristics / Stability / Biological variation / Discussion --- p.58-68 / Acknowledgements --- p.68 / References --- p.69

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 76-93).

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Leaves vi, ix and 167 are blank. Typescript. Includes bibliographical references (leaves 173-174). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Leaves vi, ix and 167 are blank. Typescript. Includes bibliographical references (leaves 173-174). Also available on the Internet.

Thesis (Ph. D.)--Lund University.

Thesis (Ph. D.)--Lund University.

Thesis (Ph. D.)--University of Missouri--Columbia, 1998. / "July 1998." Typescript. Vita. Includes bibliographical references (leaves 138-170). Also available on the Internet.

Master of Science / Biochemistry and Molecular Biophysics Interdepartmental Program / Gerald Reeck / Pea aphids (Acyrthosiphon pisum) are sap-sucking insects that feed on the phloem sap of some plants of the family Fabaceae (legumes). Aphids feed on host plants by inserting their stylets between plant cells to feed from phloem sap in sieve elements. Their feeding is of major agronomical importance, as aphids cause hundreds of millions of dollars in crop damage worldwide, annually. Salivary gland transcripts from plant-fed and diet-fed pea aphids were studied by RNASeq to analyze their expression. Most transcripts had higher expression in plant-fed pea aphids, likely due to the need for saliva protein in the aphid/plant interaction. Numerous salivary gland transcripts and saliva proteins have been identified in aphids, including a glutathione peroxidase. Glutathione peroxidases are a group of enzymes with the purpose of protecting organisms from oxidative damage. Here, I present a bioinformatic analysis of pea aphid expressed sequence tag libraries that identified four unique glutathione peroxidases in pea aphids. One glutathione peroxidase, ApGPx1 has high expression in the pea aphid salivary gland. Two glutathione peroxidase genes are present in the current annotation of the pea aphid genome. My work indicates that the two genes need to be revised.