In this study bioluminescence-marker systems were used to investigate the fate of two genetically engineered degradative bacteria in soil under different conditions. These bacteria were chromosomally <I>lux-</I>marked <I>Alcaligenes eutrophus </I>H850 Lr with <I>lux</I>AB genes which was able to degrade polychlorinated biphenyls (PCBs), and <I>Pseudomonas stutzeri </I>P16. <I>P. stutzeri </I>P16 was genetically marked with the <I>lux</I>AB <I>tet</I> cassette by insertional mutagenesis using mini Tn5-transposons and was characterised for <I>lux</I> gene stability, phenanthrene degradability and sensitivity to aldehyde. Insertion of <I>lux</I> gene into genome of <I>P. stutzeri</I> P16 provided a novel strain with lower maximum specific growth rate and less sensitivity to high concentrations of phenanthrene in liquid culture. Survival and activity of <I>P. stutzeri</I> P16 <I>lux</I>AB4 was further investigated in soil amended with low and high concentrations of phenanthrene. Initially high concentrations of phenanthrene had a less toxic effect on viable cell concentrations and luminescence activity of genetically engineered <I>P. stutzeri</I> P16 comparing with its wild type showing that <I>lux</I>-marking the above degradative strain made the marked strain more suitable for environmental application in heavily polluted sites. However, resistant cells to high concentration of phenanthrene were not able to survive longer than those which was inoculated to microcosms with lower concentrations of phenanthrene. This indicates that toxicity of the target compound and its concentration have to be considered before releasing the GEMs. Degradation of phenanthrene was enhanced in both sterile and non-sterile soil inoculated with <I>P. stutzeri </I>P16 <I>lux</I>AB4. This study could be used as model for further investigated of degradation of other PAHs such as fluoranthene, benz[a]anthracene, benzo[a]pyrene, by degradative bacteria and also monitoring the survival and activity of those bacteria in the environment using bioluminescence-marker systems.

The aim of this work was to develop and test a mathematical model for DNA transfer by conjugation which considered spatial separation of cells on surfaces. Model parameters include the initial donor and recipient numbers, maximum specific population growth rate, microcolony radial extension rate, maximum cell yield, maximum incubation time, standard deviation of the mean intercellular distance (σ), cellular area and area available for colonization. Sensitivity analysis indicated that growth areas and σ had the greatest effects on conjugation. The model was extended to consider the presence of a strain that did not conjugate and its effect on plasmid transfer. Filter matings with <I>Pseudomonas fluorescens</I> MON787 RP4 as the plasmid donor and <I>P. fluorescens</I> MON787 R <I>lux</I> as recipient were used to test the model. Model predictions were generally accurate but transconjugants were consistently underestimated. This was attributed to intercellular distances not following a strict Gaussian distribution. Nevertheless, predicted and experimental data were qualitatively similar, which increased confidence in the validity of the mechanisms proposed. Conjugation occurred over a wide range of cell densities, donor to recipient ratios, nutrient levels and incubation temperatures. Starved cells retained the capacity to conjugate, but plasmid transfer frequency was higher in the presence of nutrient. Above a minimum level, conjugation ability was not enhanced by nutrients. Temperature affected conjugation ability, the optimum being 20°C - 30°C. The presence of a nonconjugative strain decreased conjugation, by leading to earlier nutrient exhaustion and growth arrest which limited meetings between donor and recipient microcolonies. The model and the experimental system demonstrate the importance of spatial effects on conjugation. Description and prediction of gene transfer in natural environments will require models of greater complexity, and more sophisticated experimental testing, but this study provides a basis for theoretical descriptions of gene transfer in heterogeneous natural environments, such as soil and biofilms on solid surfaces in aquatic environments.

No description available.

The National Bioengineered Food Disclosure Standard (PL 114-216) will require nearly all foods sold in the U.S. to bear a statement disclosing whether they contain genetically modified (GM) material. Past studies suggest the presence of such a statement could have profound effects on consumers; however, research comparing consumer response towards different GM-disclosure statements is scarce. PL 114-216 states that GM foods shall not be considered more or less safe than their non-bioengineered counterparts, nevertheless it would benefit regulators and food manufacturers to be aware of the possible effects such disclosures might have on consumers. In a nationwide survey, multiple disclosure statements with varying degrees of public familiarity were compared to evaluate consumer perceptions and attitudes associated with each statement. Average consumer knowledge level of GM processes was also measured. The statements were then paired with actual food items to determine whether specific product categories influenced consumer responses. A select few of these statements and foods were included in a taste panel, allowing researchers to analyze if disclosure statements affected a consumer's sensorial experience. Results suggested that consumers were most favorable towards statements indicating the absence of GM-material, however they also responded less negatively towards new disclosure statements that do not have negative connotations. Additionally, consumers may react differently depending on the food accompanying a particular disclosure, although the taste panel data found no evidence that statements affected actual eating experience. Importantly, data from both surveys and taste panel suggested a disclosure statement may affect consumer willingness to buy a product.

No description available.

No description available.

Science can define what is practicable, what can be done, but it cannot determine which developments it is right to pursue- this is largely an ethical judgment attempting to answer ‘ought we to do it’? The most sensible approach to making an ethical assessment is to try and weigh up the benefits of a novel technology against its potential to do harm. Deciding whether GM technology is acceptable in ethical terms involves a judgment about both the plausibility and moral weight of competing sets of claims, beginning with an assessment of the possible benefits and risks. Using four main guiding principles as the basis of my discussion and point of evaluation, I focus firstly on the principle of general welfare to examine the debate what would amount to an adequate safety assessment of GM foods and its possible ecological risk. The right of consumers to freedom of choice is addressed by exploring both the arguments against and for labelling. The principle of justice then questions the claims whether food security can indeed be improved by using GM technology and how patents, bioprospecting and biopiracy can be judged ethically justifiable. Finally the ethical status of the natural world is raised by attempting to answer whether modern biotechnology could be considered blasphemous and whether it is ethically permissible to breach the natural integrity of the species. Using these guiding principles do not make such as assessment straightforward as they cannot be rigidly applied in an abstract way to reflect absolutes on what is right or wrong and their operation depends on context. My approach is normative and presented in a way to stimulate dialogue as an explorative ethical travel through the genetically modified zone with the recognition that the debate remains inconclusive and controversial. Keywords: GM; Genetically Modified Foods; GM Technology; Transgenic.

The Biotech dispute at WTO received a great deal of attention, and reopened a wide-ranging debate over the benefits of genetically modified organisms (GMOs) and their effects on human health and the environment. The dispute was complex and involved a high level of political sensitivity. It brought attention to procedural and substantive issues in which the roles of science and precaution, and the interrelationship between trade law and international law took centre stage. It raised questions as to the degree of risk acceptable to society, as well as questions regarding the regulation of GMOs in the face of continuing uncertainty about the risks they may pose to human health and the environment. This thesis explores both the conceptual foundations and the legal aspects of this debate. It argues that extending the scope of the SPS Agreement in the manner the Biotech decision did is problematic, and overburdens the EU with demonstrating that its GMO authorisation framework is based on scientific risk assessments and not otherwise disguised restrictions on trade. This thesis also highlights that the conflict surrounding GMOs is not limited to the World Trade Organization. By leaving little room for the application of precautionary approaches and non-scientific factors, the Panel largely failed to recognise the institutional and discursive complexity in which the conflict about GMOs is embedded. The thesis concludes that increased sensitivity of WTO law to environmental and non-scientific factors will reduce the existing tension allowing it to coexist with other international treaties.

Thesis (M.S.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 95-99). Also available on the Internet.

Thesis (M.S.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 95-99). Also available on the Internet.