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PhD Dissertation Sandra Un Jan with corrections 21.82 MB
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Dissertation
The Environmental Fate and Effects of Antibiotic Resistance Genes and Small Interference RNAs from Genetically Modified Crops
Washington State University
Doctor of Philosophy (PhD), Washington State University
2023
DOI:
https://doi.org/10.7273/000006369
Abstract
Rising global populations have amplified food scarcity across the world and accelerated the development of genetically modified crops to overcome these challenges. Cultivation of major crops such as corn and soy has favored genetically modified crops over conventional varieties to meet crop production and resilience needs. Modern genetically modified crops containing small interference RNA molecules and antibiotic resistance genes have become increasingly common in the United States. However, the use of these crops remains controversial due to the uncertainty regarding the unintended release of its genetic material into the environment and possible downstream effects on human and environmental health. DNA or RNA transgenes, which are considered emerging contaminants, may be exuded from crop tissues during cultivation or released during plant decomposition and adsorbed to soils. This can contribute to the persistence and bioavailability in soil or water environment and possible uptake by soil microbial communities and further passing of this information to neighboring bacteria, disrupting microbial ecosystem services such as nutrient cycling and soil fertility. In this dissertation, the fate, transport, and non-target effects of model antibiotic resistance genes and small interference RNAs were explored. The specific objectives of this research were to 1) evaluate the fate of transgenes in soil-saturated environments using lab-scale batch reactors; 2) quantify transgene transport using soil columns and characterize microbe-transgene interactions; and 3) evaluate the influence of potential non-target gene silencing caused by small interference RNAs in common soil bacteria using the GeoChip 5S microarray. This study aims to expand the current state of knowledge on potential environmental consequences posed by these emerging contaminants. This research determined that transgenes can be persistent in soil-saturated environments, which suggests the bioavailability of these genetic constructs for downstream microbial transformations. It was also found that transgenes can be transported across soil columns and interact with the microbial communities in the system. These interactions were then determined to result in an overall decrease in the microbial population in the system and significant variations in the genetic expression of important nutrient-cycling genes.
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Details
- Title
- The Environmental Fate and Effects of Antibiotic Resistance Genes and Small Interference RNAs from Genetically Modified Crops
- Creators
- Sandra Paola Un Jan Contreras
- Contributors
- Courtney M Gardner (Advisor)Timothy R Ginn (Committee Member)Lauren K Redfern (Committee Member)Markus Flury (Committee Member)Amanda K Hohner (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Civil and Environmental Engineering
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 174
- Identifiers
- 99901087514401842
- Language
- English
- Resource Type
- Dissertation