Effects of Salt Concentration on Tetrahymena thermophila Growth and CRP1 Gene Expression

The use of salt to remove ice from roads has resulted in increased salinity in many freshwater lakes in North America. For this project, we wanted to explore how environmental salt concentrations influence the rate of growth of Tetrahymena thermophila and expression of the CRP1 gene. We hypothesized that if the sodium concentration is increased in the media, Tetrahymena growth would decrease and expression of the CRP1 gene would increase. The CRP1 gene encodes a protein that helps regulate calcium concentrations within a cell based on the concentration of sodium ions. The media of the experimental group was treated with sodium concentrations reflective of the increasing salt concentration of freshwater lakes. Cultures were randomly assigned to either the control group, containing no added sodium, or to the experimental group. The course of treatment lasted for 3 days and growth of the Tetrahymena was measured every 24 hours during the treatment period. Immediately following the 72-hour treatment, RNA extraction procedures were followed and gene-specific Reverse Transcription Polymerase Chain Reactions (RT-PCRs) were performed on both the control and experimental groups to measure expression of CRP1. Increased sodium concentration in the media was predicted to decrease Tetrahymena thermophila growth and increase CRP1 expression in order to help regulate ion concentrations within the cell