CONTAMINATION EVENTS AND LINKAGES IN WORLD RICE MARKETS

AN ABSTRACT OF THE THESIS OF Mana-anya Iemsam-arng, for the Master\u27s degree in Agribusiness Economics, presented on November 9, 2010, at Southern Illinois University Carbondale. TITLE: Contamination Events and Linkages in World Rice Markets MAJOR PROFESSOR: Dr. Dwight Sanders In August of 2006, genetically modified LibertyLink rice contaminated the supply of non-GMO rice in the United States, causing damage to the U.S. rice production sector\u27s credibility in their export market. The damage to the United States\u27 credibility included doubt as to whether or not they had the ability to separate GMO and non-GMO rice strains during planting and/or production. This caused a short-term decline in the price of U.S. rice. The purpose of this paper is to examine rice price relationships from August 1997 to February 2010 among the four major rice exporting countries (Thailand, Vietnam, the United States, and India) before and after the genetically modified rice contamination event. Using unit root tests and cointegration tests, the results show that international rice export prices are independent from each other, yet the U.S., Thailand, and Vietnam 5 percent broken DWP rice prices tended to change in the same direction. The fact that the change in rice prices occurred right after the U.S. GMO contamination event of August 2006 is statistically significant. However, the results of this study cannot be proven to indicate that the contamination event\u27s impact caused this change in rice export prices. Keywords: Rice prices, Contamination Event

Poly(ethylene) glycol based Delivery Systems for Nucleic Acid Therapies

Our work is aimed at developing a synthetic biocompatible gene and siRNA delivery system for the treatment of primary and metastatic tumours. To facilitate delivery of nucleic acid based drugs into the cell, one strategy is to formulate the naked gene with an amine based non-viral gene delivery system via the counterion interaction. The delivery systems including 4arm-PEG-amine, 4arm-PEG-N-2-ethylamine, 8arm-PEG-amine and 8arm-PEG-N-2-ethylamine were synthesised, characterised and complexed with a reporter gene (β-gal plasmid DNA) in phosphate buffer pH 6.0. The resulting complexes were sized and their zeta potential measured (Malvern Zetasizer 3000HS, Malvern Instruments, UK). The complexes were also imaged using transmission electron microscopy and characterised for DNA binding and DNA protection using gel electrophoresis and the ethidium bromide displacement assay. The in vitro transfection efficiency and cell cytotoxicity of the complexes were determined in the A431 and HeLa cells. Additionally, in vivo therapeutic studies in female nude tumour bearing mice were carried out. A promising DNA-polymer complex of 4arm-PEG-N-2-ethylamine produced a complex of 200-300 nm in diameter (polydispersity < 0.6). Complexes had a zeta potential of +19.8 mV (n=3) and were spherical, fibrillar and toroidal in shape. The new gene delivery complex protected DNA from degradation in serum up to 2 hours and was as efficient as poly(ethylenimine) (PEI) in transfecting the A431 cell line, but it was more than 3 orders of magnitude less cytotoxic than PEI. In vivo a gene medicine, comprising the polymer and the tumour necrosis factor alpha gene, was tumouricidal. When complexed with siRNA, the siRNA polymer complex demonstrated a trend of gene silencing activity. A new synthetic gene delivery polymer of 4arm-PEG-N-2-ethylamine has been synthesised. This polymer is biocompatible to cells and is an efficient in vitro and in vivo gene transfer agent