Liver glutathione peroxidase activity is affected by changes in selenium (Se) status. To investigate the effect of Se status on GSH-Px protein we prepared antibodies against rat liver GSH-Px and used them in an ELISA. The immunoreactivity of the anti-GSH-Px antibodies against GSH-Px was both tissue and species specific. When rats were depleted of Se, liver GSH-Px activity decreased exponentially to zero with a half-life of 2.8 d. Liver GSH-Px protein also decreased exponentially, but not to zero, with a longer half-life of 5.2 d. Dietary repletion of Se-deficient rats with 0.5 mg Se/kg diet increased GSH-Px protein and activity after 1 d. After 14 d of repletion the levels of GSH-Px protein and activity had plateaued at the levels present in Se-adequate rats. When Se-deficient rats were injected with 15 or 60 ug Se, only rats injected with 60 ug Se and killed 24 h later showed an increase in GSH-Px protein and activity. These results suggest that when Se is limiting, GSH-Px protein and GSH-Px activity are coordinately regulated by the available Se, but in Se-adequacy homeostatic processes control the level of GSH-Px.

The effects of dietary methionine (Met) on the utilization of selenium (Se) from stored tissue Se and dietary selenomethionine (SeMet) for glutathione peroxidase (GSH-Px) synthesis were studied in male rats. Plasma, liver and muscle Se significantly increased when rats were fed 0.5 mg Se/kg diet as SeMet in a Met-deficient diet for 21 d, whereas tissue GSH-Px activities decreased 43-50% during the SeMet supplementation period, suggesting that Se is deposited as SeMet in general body proteins. By calculation, a significant lower percentage of Se was associated with GSH-Px in Met-deficient as compared to Met-supplemented rats. Dietary Met supplementation increased the incorporation of 75Se from 75SeMet into specific rat selenoproteins in addition to liver GSH-Px. Overall, these results suggest that intact SeMet is preferentially incorporated non-specifically into general body proteins in Met-deficient rats, whereas with supplemental Met, more SeMet is degraded and the released Se used for specific selenoprotein synthesis. (Abstract shortened with permission of author.)

Thesis (M.Sc.Agric.(Animal Science))--University of Pretoria, 2002. / Summaries in Afrikaans and English. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1939. / Typescript. Includes abstract and vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Please read the abstract in the section 00front of this document. / Dissertation (MSc (Agric) Animal Nutrition)--University of Pretoria, 2006. / Animal and Wildlife Sciences / unrestricted

Call number: LD2668 .T4 1958 O52

No description available.

Includes 25 papers previously published in Journals / 114, 16 leaves : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (D.Sc.)--University of Adelaide, Dept. of Biochemistry, 1975

Two studies were conducted to determine the effects of zinc (Zn), copper (Cu) and/or selenium (Se) on the humoral immune response of weaned steers fed diets deficient in these minerals. Steers were bled weekly for eight weeks to measure plasma mineral levels. Humoral immune response was measured as antibody response to Keyhole limpet hemocyanin (KLH) over seven weeks of the trials. Steers were injected with 0.5 ml KLH vaccine on weeks 2 and 5 of the Zn study. Ten steers (5 per treatment) were randomly assigned to either a Zn supplemented (z), 3.25 ml injectable zinc-oxide suspension (100 mg/ml oil) or a control (c) treatment. Plasma Zn was maintained at higher (P<.05) levels in supplemented steers from week 3 through week 8. Humoral immune response was not different (P>.10) between treatments. In 1988, 20 steers were stratified by weaning weight and randomly assigned to one of four treatments: 1) Injectable Se 1 ml Mu-Se/ 90.9 kg body weight, 2) Injectable Molycu 2 ml, 3) control, or 4) Se + Cu. Plasma Cu was higher (P<.05) in treatments 2 and 4 from week 2 through 8. Steers were injected with 0.5 ml of KLH vaccine on weeks 2 and 6. Immune response was not different (P>.10) between Cu supplemented steers and other treatments. Plasma Se was higher (P<.05) in treatment 1 as compared to 2 and 3, but not different (P>.10) from 4. Immune response was highest (P<.05) in treatment 1 with others not different(P>.10). In 1990, a second trial was conducted with 48 steers stratified by weight and randomly assigned to one of the same four treatments. Plasma Cu was higher (P<.05) on week 3 for both groups receiving Cu. Plasma Se was higher (P<.05) on weeks 2 through 5 for both groups receiving Se. Humoral immune response was higher (P<.05) on weeks 7 and 8 for both groups receiving Se. Humoral immune response was uneffected by Zn status of weaned beef steers. Selenium had a positive effect and Cu had no effect on humoral immune response of weaned beef steers. Copper also tended (P=.07) to reduce the positive response from Se. / Graduation date: 1991

No description available.