Investigating the Effect of Phytosterol Concentration on the Des7 Gene and Feeding Behavior in Tetrahymena thermophila

Abstract

This study examined the impact of phytosterols on DES7 gene expression and feeding behavior in Tetrahymena thermophila. Tetrahymena thermophila are single-celled protists that are often used as model organisms for studying basic processes of Molecular Biology. One major topic in Molecular Biology that has been extensively studied in Tetrahymena is the concept of gene regulation. Gene regulation helps determine whether a certain protein is produced, and this often depends on both the internal and external conditions of the organism. This project took a closer look at the way Tetrahymena process exogenous cholesterol molecules through the production of the DES7 enzyme. It was hypothesized that exposing Tetrahymena to increased concentrations of phytosterols would increase expression of the DES7 gene and increase feeding behavior. This hypothesis was tested by exposing experimental Tetrahymena cultures to phytosterols through the introduction of corn oil into their growth media. The cultures were maintained for seven days, during which time a feeding assay was performed to determine the number of food vacuoles being produced by the Tetrahymena. At the end of the week-long treatment period, RNA was extracted and Reverse Transcription – quantitative Polymerase Chain Reactions (RT-qPCRs) were performed to measure DES7 expression levels. We predicted that exposure to phytosterols would lead to an increase in DES7 gene expression and an increase in feeding behavior.