Brosnan, Laura2011-12-142011-12-142011-12-14https://hdl.handle.net/11299/119034The majority of eukaryotic cells exist in a quiescent state outside of the cell cycle known as stationary phase, or G0. Although quiescent cells are non-proliferating, they retain the ability to reenter the cell cycle. Events such as DNA alterations can take place in stationary phase cells that are associated with a risk for inappropriate reentry into the cell cycle and the development of cancer. Such alterations can occur in repetitive tracts of DNA known as minisatellites. When change in the number or order of minisatellite repeat units occurs, rare alleles of minisatellite tracts may arise. Many of these rare alleles are associated with human diseases, including cancer, diabetes, and epilepsy. Previous work in our lab has demonstrated that certain genes are involved in regulating the stability of a synthetic minisatellite in stationary phase cells. In order to relate these findings to the association between minisatellites and human disease, we inserted the human minisatellite associated with the HRAS1 oncogene into the ADE2 gene of S. cerevisiae to determine how its stability is regulated during stationary phase. Our lab has developed a novel assay for studying stationary phase minisatellite stability in S. cerevisiae. When minisatellites are destabilized and undergo a change in repeat number or order, a novel color phenotype known as blebbing occurs. Blebbing mutants were constructed and we found that the zinc transporter ZRT1, the DNA repair gene RAD27, the checkpoint gene RAD53, the Polε subunit DPB3, and several checkpoint genes (including MRC1, TOF1, CSM3) regulate the stability of the human HRAS1 minisatellite. Upon examination of minisatellite alterations in these blebbing mutants, we saw both expansions and contractions of the minisatellite tract; through further analysis, these alterations were found to be dependent upon homologous recombination.en-USSumma Cum LaudeBiologyCollege of Biological SciencesThesis or Dissertation