Effect of Potassium Bromate on OXR1 Gene Expression and Cell Growth in Tetrahymena thermophila

Abstract

The purpose of our experiment was to answer the question: Does oxidative damage, induced by potassium bromate (KBrO3), affect growth rate and expression of the OXR1 gene in Tetrahymena thermophila? Potassium Bromate was chosen as the environmental stressor because it is a strong oxidizing agent that is used as a leavening agent in baked goods. It was hypothesized that expression of OXR1 would increase in Tetrahymena cells that were exposed to potassium bromate and that their growth rate would decrease. The exact mechanism and function of the OXR1 gene is still unknown; however, the literature suggests that it is required for oxidative damage resistance. To test the hypothesis, Tetrahymena were randomly assigned to either a control group or a test group. A solution of potassium bromate that was pre-determined to be non-lethal to the Tetrahymena was added to the test groups culture media and both the control and test groups were cultured under ideal conditions for 72 hours. During the 72hr time-period, Tetrahymena were counted twice a day to determine their growth rate. Following the 72-hour treatment period, RNA was extracted from the control and test groups. Reverse Transcription-Polymerase Chain Reaction (RT-PCR) was performed on the extracted RNA, followed by gel electrophoresis and a semi-quantitative analysis of OXR1 expression. Due to the strong oxidizing capacity of potassium bromate, it was predicted that there would be significant oxidative damage resulting in increased expression of OXR1 in the Tetrahymena cultures that were treated with potassium bromate.