Dissertations, Theses, and Capstone Projects
Date of Degree
2-2014
Document Type
Dissertation
Degree Name
Ph.D.
Program
Physics
Advisor
Mark Hillery
Subject Categories
Biology | Biophysics | Physics
Keywords
Bacterial Evolution, Horizontal Gene Transfer, Population Dynamics, Spontaneous Mutation
Abstract
This thesis studies the two fundamental mechanisms of bacterial evolution — horizontal gene transfer and spontaneous mutation, in the bacterium Escherichia coli through novel experimental assays and mathematical simulations. First, I will develop a growth assay utilizing the quantitative polymerase chain reaction (qPCR) to provide real-time enumeration of genetic marker abundance within bacterial populations. Second, I will focus on horizontal gene transfer in E. coli occurring through a process called conjugation. By fitting the qPCR data to a resource limited, logistic growth model, I will obtain estimated values of several key parameters governing the dynamics of DNA transfer through conjugation under two different conditions: i) in the absence of selection; ii) in the presence of negative selection pressure — bacteriophage infection. Last, I will investigate spontaneous mutation through qPCR assay of competition between wild-type and mutator phenotype E. coli. Mutator phenotype has an elevated mutation rate due to defects in DNA proofreading and repairing system. By introducing antibiotic selective pressure, I will examine the fixation probability of mutators competing with wild-type in novel environment. I also will utilize simulations to study the impact of three parameters on the fixation probability.
Recommended Citation
Wan, Zhenmao, "An experimental investigation into the mechanisms of bacterial evolution" (2014). CUNY Academic Works.
https://academicworks.cuny.edu/gc_etds/125