Honors Theses

Date of Award

5-2025

Document Type

Undergraduate Thesis

Degree Name

BS

Department

Biomedical Sciences

Faculty Mentor

Glen M. Borchert

Advisor(s)

Jeffrey De Meis, Raymond Langley

Abstract

Small RNAs (sRNAs) are noncoding RNA molecules in bacteria that function primarily to regulate gene expression, including those associated with stress. The Borchert Lab has identified 173 sRNAs and > 500 sRNAs that are responsive to desiccation and carbon starvation (c-starvation), respectively. Prokaryotic transcription involves an RNA Polymerase (RNAP) that transcribes DNA into RNA. RNAP involves sigma factors, which recognize promoters for the initial steps of RNA synthesis. The Borchert Lab has determined that there are significant overlaps between sRNAs expressed in cells subjected to both short-term durations and long-term durations of carbon starvation. Salmonella enterica serovars can have outbreaks associated with dehydrated foods. Understanding the mechanism that allows for S. enterica survival under stress allows for building strategies in combating the spread of this pathogen and preventing recurrent Salmonella outbreaks. We hypothesize that in S. enterica serovars, the bacteria express sigma factor RpoS during short term stress while switching over to sigma factor RpoE during long term stress. This switch between the sigma factors function to regulate the stress response in S. enterica. RNAP sigma subunit selection and the expression of distinct sRNAs drive the decision between active stress resistance and formation of persisters. Our findings suggest that sigma factor expression of RpoS in the Salmonella strain SL1344 is dependent on the duration of stress.

Comments

© 2025 Anita D. Nguyen ALL RIGHTS RESERVED

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