Browsing by Subject "Selenium"
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Item The effects of sulfur and selenium on glucoraphanin and seleno-methylselenocysteine concentrations in broccoli (Brassica oleracea L. italica)(2015-05) Doberstein, AnnieGlucosinolates (GLSs) are sulfur-containing secondary metabolites produced by broccoli (Brassica oleracea subsp. italica) and other cruciferous vegetables. GSLs exist for use in plant defense, but are gaining research interest for their role in cancer prevention. Glucoraphanin (GR) is a particular glucosinolate found in broccoli that has great health benefit potential. Seleno-methylselenocysteine (SeMSC) is another compound unique to broccoli when it has been exposed to selenium during plant growth, and is also of interest for its chemopreventive potential. To understand the relationship between root fertilization of sulfur and selenium on GR and SeMSC concentrations in a production environment, we exposed a low-GR ("Green Magic") and a high-GR ("Beneforte") broccoli to sulfur (0 - 34 kg.ha��) and selenium (0 - 3.36 kg.ha��) fertilization treatments in the field. GR and SeMSC concentrations depended upon cultivar, treatment, and environmental factors."Beneforte" consistently delivered the highest GR concentration, and "Green Magic" the lowest, and "Beneforte" GR concentrations were less affected by the presence of Se treatments than "Green Magic". "Beneforte" also accumulated higher concentrations of SeMSC overall than "Green Magic". A colder, wetter spring in 2013 led to reduced sulfur uptake and lower concentrations of GR overall, while a warmer, drier climate during later Se applications increased Se uptake and subsequent SeMSC concentrations. Contrasting, a warmer, dryer spring the following year gave way to increased sulfur uptake and greater GR concentrations, and wetter, cooler conditions during Se applications negatively impacted SeMSC concentrations overall. To assess the efficacy of foliar Se fertilization as an alternative to root application, the same two varieties were grown in a greenhouse and were subjected to one of four sodium selenate treatments (0 - 93.74 mg Se.plant�). Again, Se significantly affected the concentration of GR in "Green Magic", but not in "Beneforte". Overall, a weak relationship between GR and SeMSC concentrations give a promising outlook to the ability to maximize GR and SeMSC for ultimate benefit upon consumption of broccoli. This is especially true in "Beneforte", where GR concentrations remain relatively stable in the presence of Se, but still allow Se uptake and SeMSC formation.Item An Interdisciplinary Geochemical and Genomics Approach to Understanding Fungal Selenium Transformations for the Bioremediation of Contaminated Waters(2021-07) Sabuda, MarySelenium (Se) is both a micronutrient required for most life and an element of environmental concern due to its toxicity in high concentrations. Se can be released into the environment through both natural and anthropogenic (human) activity, where it can exist as volatile or organic Se(-II), nanoparticulate Se(0), or aqueous Se(+IV/VI). Coal mining, processing, and burning can release high levels of Se to the environment, as selenium can easily substitute for sulfur, a main component of coal. Se is also useful in the medical field, where it has anticancer properties and Se(0) is an effective coating on medical devices. While most knowledge of biotic Se transformations is related to either anaerobic or aerobic bacterial processes, some common soil Ascomycota fungi can reduce Se under oxic conditions. These microeukaryotes readily transform elevated concentrations of this essential toxin from a bioavailable aqueous phase (Se(IV/VI)) to solid or volatile phases (Se(0/-II)), which is ideal for engineering efficient, cost-effective treatment strategies for Se-contaminated environments. Elucidating the geochemical and genetic mechanisms behind filamentous fungal Se transformation strategies will progress biotechnological applications for biogenic Se nanoparticles, and aid in a more complete understanding of Se biogeochemical cycling.