http://hdl.handle.net/1957/494 Search the Channel search http://ir.library.oregonstate.edu/dspace/simple-search http://hdl.handle.net/1957/8494 Title: Physiological, proteomic, and whole-genome transcriptional responses of Nitrosomonas europaea to heavy metals (Zn²⁺,Cd²⁺, Cu²⁺, and Hg²⁺) and cyanide : identification of heavy metals and cyanide stress response genes <br/> <br/>Abstract: Nitrosomonas europaea (ATCC19718) participates in the biological removal of nitrogen from wastewater by oxidizing ammonia to nitrite, the first step in nitrification. This bacterium is sensitive to heavy metals (Zn²⁺, Cd²⁺, Cu²⁺, and Hg²⁺) and cyanide, compounds commonly encountered in wastewater treatment plants. Therefore, we characterized physiological and transcriptional responses of N. europaea cells exposed to these inhibitors in batch reactors to identify stress-induced genes. N. europaea exposed to 3.4 uM ZnCl₂ showed about 61% inhibition in nitrification within 30 minutes. In microarrays of N. europaea exposed to 3.4 uM ZnCl₂ for 60 minutes, 27 genes were observed to be up regulated more than 2-fold, of the total of 2460 genes, while 30 genes were seen to be down regulated. Up-regulated genes included mercury resistance genes (merTPCAD), inorganic ion transport genes, oxidative stress genes, toxin-antitoxin genes (TA). merTPCAD was the highest up regulated operon (46-fold). Down- regulated genes included RubisCO (cbbO), biosynthesis (mrsA), and amino acid transporters. N. europaea exposed to 1 uM CdCl₂, 6 uM HgCl₂, or 8 uM CuCl₂ showed about 90% inhibition in nitrification within 30 minutes. In microarrays of N. europaea exposed to 1 uM CdCl₂ for 60 minutes, 66 genes were up regulated while 50 genes were down-regulated. merTPCADE showed the highest up regulation (277-fold) under cadmium stress. Interestingly, merA also showed 250-fold up regulation in N. europaea cells exposed to 6 uM HgCl₂. Therefore, merTPCADE appear to be common stress response genes to zinc, cadmium, and mercury exposure. N. europaea cells were very sensitive to low concentrations of cyanide; nitrification decreased about 50% in 30 minutes after exposure to 1 uM NaCN. In microarrays of N. europaea exposed to 1 uM NaCN for 60 minutes, 35 genes showed up regulation while 29 genes showed down regulation. A gene cluster that included moeZ (NE2353), encoding a rhodanese homologue, thought to be involved in detoxification of cyanide, showed the highest up regulation (7-fold). The down-regulated genes included genes encoding proteins involved in the sulfate reduction pathway, signal transduction mechanism, carbohydrate transport, energy production, and coenzyme metabolism. <br/> <br/>Description: Graduation date: 2008 http://hdl.handle.net/1957/7649 Title: Sensitivity analysis of the Catchment Modeling Framework (CMF) and use in evaluating two agricultural management scenarios <br/> <br/>Abstract: Abstract Watershed-scale fate/transport modeling of contaminants is a tool that scientists and land managers can use to assess pesticide contamination to stream systems. The Catchment Modeling Framework (CMF) is a catchment-scale fate/transport modeling tool. It was developed to help scientists and land managers assess the effects of possible land-use decisions on water quality. This study performed a sensitivity analysis on the CMF using Extended Fourier Amplitude Sensitivity Testing (FAST) methods. The hydrology model and the pesticide model were analysed separately. Additionally, results of a local sensitivity analysis are compared to a global analysis. Finally, the model is used to assess the effectiveness of two possible land-use strategies. The sensitivity analysis showed that initial soil moisture and porosity were the dominant first-order parameters for the hydrology model. Combined, they yielded greater than 50% of the total first-order sensitivity. Results from the local sensitivity analysis compared less than favorably with the global analysis. The sensitivity analysis of the pesticide model showed that initial soil moisture, porosity and saturated hydraulic conductivity are the dominant first-order parameters, again combining to yield greater than 50% of the total first order sensitivity. The model was then used to assess the relative benefit of reducing the cultivated area of an agricultural catchment (field size) vs. reducing the amount of pesticides that land directly on the soil. Results show that reduction in field size yields little benefit when compared to reducing the amount of pesticides landing on the soil. Management implications of this finding are explored. <br/> <br/>Description: Graduation date: 2008