Date of Graduation

Spring 2018

Degree

Master of Science in Cell and Molecular Biology

Department

Biomedical Sciences

Committee Chair

Joshua Smith

Keywords

Rad51, Dmc1, Homologous Recombination, DNA repair, Tetrahymena thermophila

Subject Categories

Bioinformatics | Cell Biology | Molecular Biology

Abstract

RecA-like proteins homologs Rad51 and Dmc1 (disruption of meiotic control) promote recombination between homologous chromosomes by repairing programmed DNA Double-Strand Breaks (DSBs). Dmc1 is a Recombinase involved in meiosis-specific repair of DSBs, whereas Rad51 has been found to be involved in meiotic and non-meiotic DSBs repair. Previous studies showed that when RAD51 is overexpressed, interhomologous recombination still occurs even when DMC1 is knocked out. Dmc1 and Rad51 have not been fully characterized in the ciliate Tetrahymena thermophila. In order to more fully investigate the role of Rad51 and Dmc1 in Homologous Recombination Repair (HHR), this work focuses on using a model organism, T. thermophila, to further elucidate the contribution of Rad51 and Dmc1 in DNA repair following various genotoxic stressors (H2O2, MMS, and UV radiation). Bioinformatics was used to illustrate the extensive conservation of the Rad51 and Dmc1 homologs in various organisms and between one another. Expression of RAD51 and DMC1 was shown to be altered following exposure to H2O2, MMS, and UV radiation, and that the RAD51 expression was significantly higher than Dmc1 expression levels following all DNA damaging agents. Localization studies using Green fluorescent protein (GFP) and Red fluorescent protein (RFP) tagged to RAD51 or DMC1 and introduced back into T. thermophila revealed that Rad51 does not localize to the micronucleus or macronucleus following exposure to MMS. Tagging revealed that Dmc1 may localize in the micronucleus without DNA damage but does not localize after MMS treatment. Both proteins showed localization outside the nuclei, suggesting expression of the tagged Rad51 and Dmc1 in T. thermophila

Copyright

© Amaal Abulibdeh

Open Access

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