Tetrahymena thermophila contains 18 putative histone deacetylases (HDACs) homologs. Eleven of these homologs are in the Sirtuins subfamily (NAD-dependent Histone Deacetylases). Sirtuins plays a key role in many functions in the cell such as cellular metabolism, removing acetyl groups on histones as well as other proteins in the cell, and have been show to have a role in cancer, neurodegeneration and cardiovascular disease. The scope of this research is to study the localization and expression levels of Tetrahymena Histone Deacetylases 10, 17, and 18 (THD10, THD17, and THD18), which are homologs of SIRT4 and SIRT5 in humans. To characterize these genes bioinformatic analysis was conducted and then PCR was performed to amplify the gene. The gene product was cloned into the pENTR-TOPO-D plasmid, transformed into E. coli, and ultimately to study the localization tagged with GFP and other epitope tags to study the function within the cell. The expression of these genes has been analyzed under various damaging agents at various time points through qRT-PCR. The damaging agents used in these studies are hydrogen peroxide, methyl methanesulfonate, ultraviolet light that creates distinctive DNA damage and DNA repair responses. This research will better elucidate if there is a possible function of the Tetrahymena SIRT4 and SIRT5-like homologs (THD10, THD17, and THD18) within DNA damage repair by studying both the localization and expression levels under different conditions.