http://hdl.handle.net/1957/456 Search the Channel search http://ir.library.oregonstate.edu/jspui/simple-search http://hdl.handle.net/1957/12715 Title: Antibiotic Resistance Gene Transfer in Oysters as a Result of Fecal Pollution<br/><br/>Authors: Cooper, Rebecca<br/><br/>Abstract: Antibiotic resistance is an increasing problem in many species of bacteria today, with pathogens an important focus. Fecal contamination of shellfish is already a concern due to potential pathogens. This report examines the possibility of resistance gene transfer between microbes, due to fecal bacteria, within the oyster. In this study, the transfer of a tetracycline resistance gene, tetQ, in a quasi-natural environment is examined. A donor strain of Bacteroides thetaiotaomicron, a species that can be found in feces, successfully transferred a tetQ containing conjugative transposon to a recipient B. thetaiotaomicron strain. Oysters were exposed to various treatments and controls, and examined for the presence of transconjugant microbial colonies. Transconjugant colonies were recovered from the bodies of experimental oysters, and verified via growth on selective media and PCR amplification. The preliminary work in this report indicates that fecal bacteria could initiate resistance gene transfer between microbes within oysters.<br/><br/>Description: Graduation date: 2001 http://hdl.handle.net/1957/12714 Title: Quantifying the Potential of Native Plants for Improving Pollination and Biological Control in Agroecosystems<br/><br/>Authors: Winfield, Tammy L.<br/><br/>Abstract: Agricultural areas can be inhospitable to the attraction and maintenance of beneficial insects like natural enemies and pollinators and this can result in a decrease in the ecosystem services of pollination and pest control that these insects supply. If habitat can be created and maintained on-farm, an increase in the numbers and diversity of beneficial insects could be seen which could correspond to an increase in ecosystem services. This study was undertaken to quantify what insect communities are supported by a set of native Oregon plants and to test for differences in the relative attractiveness of plant species to three broad categories of insects: herbivores, natural enemies, and pollinators. This first season of research shows that plant species vary in their relative attractiveness to the three functional groups of insects. Some of this variation is likely related to differences in flowering phenology. There was a significant positive association between percent peak bloom and the number of natural enemies collected on a particular plant species. The numbers of natural enemies, herbivores, and pollinators collected on plant species also varied across sites, suggesting that landscape characteristics also influence the insect communities associated with particular plant species.<br/><br/>Description: Graduation date: 2010 http://hdl.handle.net/1957/12640 Title: Integration of embryonic zebrafish and passive sampling device extracts to explore effects of pesticide mixtures<br/><br/>Authors: Corvi, Margaret<br/><br/>Abstract: Pesticides are ubiquitous, with more than one billion tons of pesticide products used in the United States annually. These compounds are characterized by their toxic effects to the target organism; however, pesticides are also well known for their deleterious effects to non-target species. Because pesticides have ecological and human health effects, it is important toinvestigate their prevalence in the environment, as well as their bioavailability and toxicity.Passive sampling devices (PSD) are commonly used to evaluate contaminants, including pesticides, found in water, air and soil. The PSD used for this research is an aquatic sampler that sequesters freely dissolved non-polar and semi-polar contaminants by diffusion into and adsorption to a lipid-free polyethylene membrane tubing (LFT). Thus, PSD can act reasonably as a biological surrogate, mimicking non-dietary bioavailability. Additionally, PSD extracts are proposed to be amenable to investigate toxicity of biologically available environmental mixtures utilizing the embryonic zebrafish (Danio rerio) model. To investigate this potential application, experiments were performed to evaluate the toxicity of non-deployed blank PSD extracts andnon-deployed extracts spiked with individual pesticides or pesticide mixtures. For this proof of concept study, embryonic zebrafish were static waterborne exposed before the initiation oforganogenesis. Two time points were monitored for mortality and alterations in development. The blank extracts did not result in any adverse developmental effects, relative to non-exposedcontrols. Embryos exposed to a comprehensive fourteen compound pesticide mixture extract produced an increase in adverse developmental responses as concentration increased. Experiments investigating the toxicity of individual compounds and partial pesticide mixtures were also performed. These preliminary studies indicate that the coupling of PSD extracts and in vivo toxicological assessments is realistic.<br/><br/>Description: Graduation date: 2010 http://hdl.handle.net/1957/12611 Title: Superior Anti-tumor Activity Exhibited From a Gemcitabine Prodrug Incorporated into Lecithin-Based Nanoparticles<br/><br/>Authors: Sandoval, Michael<br/><br/>Abstract: Cancer is class of diseases that has great diversity and unfortunately is one of the leading causes of death in the United States. Chemotherapy remains an important cancer treatment modality, and superior chemotherapeutic drugs are constantly being sought. Gemcitabine is an anti-tumor chemotherapeutic drug and it is the first line of defense in treating pancreatic cancer, as well as, used in combination therapy for non-small cell lung, ovarian, and metastatic breast cancers. Patients with cancer, specifically pancreatic carcinoma, have a high mortality rate which highlights the poor anti-tumor activity of gemcitabine. The anti-tumor activity of gemcitabine shows needed improvement due to its short half-life and low specificity in patients. The objective of this study is to utilize lecithin-based nanoparticles (NP) as a delivery system for a lipophilic gemcitabine prodrug. From this current study, a maximum drug concentration of 5 mg/ml was achieved into nanoparticles, thereby improving anticancer activity of gemcitabine.Keywords: Gemcitabine, nanoparticles, chemotherapy<br/><br/>Description: Graduation date: 2010