Date of Award

Spring 1997

Document Type

Restricted Thesis

Terms of Use

© 1997 Jovanka Tepavcevic. All rights reserved. Access to this work is restricted to users within the Swarthmore College network and may only be used for non-commercial, educational, and research purposes. Sharing with users outside of the Swarthmore College network is expressly prohibited. For all other uses, including reproduction and distribution, please contact the copyright holder.

Degree Name

Bachelor of Arts



First Advisor

Amy Cheng Vollmer


The E. coli SOS response to DNA damage was investigated at the level of transcription. The E. coli recA promoter was fused to the promotorless reporter operon /em> from Vibrio fischeri. In bacterial strains carrying this plasmid-borne fusion, the transcriptional activation was assessed quantitatively and in real time by measuring luminescence. Induction was measured in response to mitomycin C (0 - 2 μg/ml) and UV irradiation (0 - 1200 J/m2). Similar studies were performed in a strain carrying the lexA^(ind) allele. In this strain, the activated RecA protease is unable to cleave and inactivate the LexA repressor. As expected, the recA::lux fusion in the lexA^(ind) strain produced no light when induced with UV and mitomycin C. Furthermore, a comparison was made between luxCDABE and lacZ as reporters in lexA+ and lexA^(ind) strains. Viability of the strains was also quantitated. In addition, the recA promoter Deinococcus radiodurans was successfully fused to the lux operon of the parent plasmid. Preliminary studies showed little transcriptional activation of this fusion in response to UV (0 - 10,000 J/m²) in exponentially growing E. coli host cells. Further studies characterized this strain in the presence of mitomycin C and showed that D. radiodurans recA::lux fusion is inducible by mitomycin C.