The term symbiosis describes a close partnership between two or more organisms whose interactions may result in beneficial or harmful outcomes to the other. These interactions are not always fixed, but rather exist upon a continuum that is influenced by environmental context and time. One factor that plays a role in influencing symbiotic outcomes is the structure of the host and symbiont population. A question in the field is how initial infections loads, long-term population dynamics, and developmental processes impact symbiotic trajectories. This thesis aims to advance our understanding of how these parameters fluctuate and relate to distinct outcomes using an easily manipulatable symbiotic model system. Here, we study the interaction between Burkholderia bacteria and the social amoeba Dictyostelium discoideum. Burkholderia is a large genus, comprising species belonging to a pathogenic cluster and a plant beneficial environmental (PBE) cluster. Three species belonging to the PBE group have been found to naturally infect D. discoideum; B. agricolaris, B. hayleyella, and B. bonniea. Burkholderia infections may be beneficial or detrimental for their amoeba host depending upon context and symbiont genotype. Using fluorescently labeled Burkholderia strains from each species in combination with flow cytometry and confocal microscopy, we interrogated the population dynamics of host and symbiont cells to elucidate potential links between infection phenotypes, symbiont genotypes, and host outcomes. The results of this study show that infection phenotypes vary across symbiont strains, with symbionts belonging to the same species generally (but not always) displaying similar characteristics. Interestingly, final infection loads do not correlate to final host outcomes. Although some symbionts demonstrate “aggressive” infection patterns, this does not necessarily result in more detrimental host outcomes, nor is the reverse scenario true.
|Commitee:||Lieble, Faith, Fowler, Tom, Greenfield, Ben|
|School:||Southern Illinois University at Edwardsville|
|School Location:||United States -- Illinois|
|Source:||MAI 81/6(E), Masters Abstracts International|
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