Master of Arts, The Ohio State University, 2022, Communication

This study serves as the first test of the Planned Risk Information Avoidance (PRIA) model proposed by Deline & Kahlor (2019). Information avoidance is an often overlooked subject of information management, and it must be studied in order to inform our understanding and allow health communicators to apply the knowledge gained in the study of information avoidance to reduce the prevalence of avoidance of health promotion messaging. The context of this study concerned parents of children age 5-11 (N=508), and their interactions with COVID-19 vaccination information for their children. Results showed that the PRIA model was largely supported by our findings, with the exception of closure and perceived behavioral control. Implications for this study are the expansion of a model dedicated to understanding avoidance, and some suggestions for how to apply these findings. This includes considering vaccination risk as separate from disease risk (in trying to combat avoidance of vaccination messaging), and using norms to influence attitudes toward avoidance, in efforts to minimize avoidance intentions.

Committee: Graham Dixon (Committee Member); Shelly Hovick (Advisor) Subjects: Communication; Health

Master of Science (M.S.), University of Dayton, 2013, Chemistry

Complete and faithful replication of a cell's genetic information is an essential process. Many enzymes are involved in the process of successfully duplicating a cell's genetic information. Helicases, DNA polymerases, ligases, nucleases, and DNA binding proteins all play a role in DNA replication. However, the integrity of these enzymes can be compromised when they encounter DNA damage, which in general could be caused by chemical mutagens, ionizing radiations, or reactive oxidative species. Bacterial cells use a pathway called "DNA replication restart" to resume DNA replication following a disruptive encounter of the DNA replication enzymes with DNA damage. This pathway is catalyzed by primosome proteins, including PriA, PriB, PriC, DnaT, DnaB, DnaC, and DnaG. The importance of DNA replication restart for bacterial cell survival is demonstrated by the inability of strains that carry mutations in key primosome genes to grow and resist DNA damaging agents. Furthermore, this pathway is specific for bacterial cells: human cells don't use the same replication restart pathway and they don't encode genes for the primosome proteins that function in bacteria. Since DNA replication restart pathways are essential for bacterial cell growth and survival and are notably absent in human cells, we seek to answer the following question: can bacterial DNA replication restart pathways be targeted with novel antibacterial compounds? In order to answer this question, we have developed an enzyme based assay for high-throughput inhibitor screening to identify compounds that block the function of the primosome proteins PriA and PriB. Several interesting lead compounds have already been identified from the preliminary screening. In this study, the lead compounds have been validated as legitimate inhibitors and characterized with respect to their potency and mechanism of action.

Committee: Matthew Lopper (Advisor); Gary Crosson (Committee Member); Mark Masthay (Committee Member); Shawn Swavey (Committee Member) Subjects: Biochemistry; Chemistry

Master of Science (M.S.), University of Dayton, 2012, Chemistry

Neisseria gonorrhoeae is the causative organism of gonorrheal infection. This pathogen shows remarkable resistance to the oxidative damaging agents released by the neutrophils. The Bacterial genome is one of the important targets of these agents and studies indicate that DNA replication restart pathways help in bypassing the hazardous effects of these oxidative agents. The DNA replication restart pathway helps to reload and restart the stalled or derailed replication machinery onto the DNA which is blocked by obstructions such as single stranded nicks, double stranded breaks, or oxidized bases. In N. gonorrhoeae, the primosome proteins PriA and PriB carry out the DNA replication restart process by forming a nucleoprotein complex with the DNA. PriA, a helicase protein, binds and partially unwinds the DNA at the fork where the replication machinery will be reloaded. PriB serves to stimulate PriAs DNA binding and unwinding activity. PriA, PriB and the DNA form a ternary nucleo-protein complex in this process. In, E. coli the PriB has a high affinity interaction with ssDNA and a low affinity interaction with PriA, while N. gonorrhoeae PriB has a high affinity interaction with PriA and a low affinity interaction with ssDNA. The first part of my research contributed to understand the features of this affinity reversal. I performed pull down experiments, DNA unwinding assays and ATP hydrolysis experiments using single point alanine mutants of PriB. From my work, I have provided evidence that in N. gonorrhoeae, PriBs ssDNA binding activity is not required for PriB stimulation of PriA helicase, unlike what is seen in E. coli. Evidence that PriA provides resistance against oxidative damaging agents bolsters the importance of DNA replication restart pathway for the survival of this disease causing bacteria. Developing antibiotics that target this pathway could be a vital event in the field of drug discovery research. In this process, we have developed an enzyme-based assay to (open full item for complete abstract)

Committee: Matthew E. Lopper PhD (Advisor); Madhuri Kango-Singh PhD (Committee Member); Shawn M. Swavey PhD (Committee Member) Subjects: Biochemistry

Master of Science (M.S.), University of Dayton, 2011, Chemistry

DNA replication restart pathways enable bacterial cells to reinitiate DNA replication when replication has been disrupted due to encounters with DNA damage, thereby allowing complete and faithful duplication of the cell's genetic information. Neisseria gonorrhoeae is a bacterium that is highly adapted to survive oxidative damage to its DNA incurred by attack from immune cells in infected individuals, suggesting that DNA replication restart pathways might play a critical role in N. gonorrhoeae pathogenicity. The bacterial helicase, PriA, is a key primosome protein that plays essential roles in DNA replication restart pathways. However, little is known of the mechanism by which PriA performs these roles in N. gonorrhoeae. I performed equilibrium DNA binding assays and DNA unwinding assays to provide insight into the mechanisms by which PriA functions in DNA replication restart pathways. I report that DNA binding by PriA is strongly dependent on the structure of the DNA. DNA substrates that resemble a DNA replication fork with a three-way branch are bound with higher affinity than partial duplex structures or single-stranded DNA. PriA-catalyzed DNA unwinding is also DNA structure-specific, and PriA-catalyzed unwinding decreases upon increasing the length of the duplex DNA, indicating that PriA is a low-processivity helicase. Another primosome protein, PriB, strongly stimulates the helicase activity of PriA, and this activity might facilitate reloading of the replication machinery by PriA at repaired replication forks. Stimulation of PriA by PriB appears to occur through a mechanism that is distinct from that used by the well-studied E. coli primosome proteins.

Committee: Matthew Lopper PhD (Advisor); Madhuri Kango-Singh PhD (Committee Member); Shawn Swavey PhD (Committee Member) Subjects: Biochemistry