Effect of Nitrate Pollution on Tetrahymena thermophila
The question under investigation in this project was: Does an elevated concentration of nitrates have a negative eect on cell growth and expression of the CDC16 gene in the organism Tetrahymena thermophila? Exposure of Tetrahymena cultures to nitrates mimics the exposure of these organisms to nitrate pollution in the environment, which can occur due to septic tank leakage, nitrogen-rich fertilizer run o, and agricultural processes. The EPA standard for nitrate concentrations in drinking water is a maximum of 10ppm. In our experiment, Tetrahymena cultures were treated with media that contained 30ppm of nitrates for one week. The 30ppm nitrate concentration has been proven acceptable for freshwater fish; therefore, we predicted that it would have more of an impact on our Tetrahymena cells which are far less complex. The CDC16 gene encodes a Cell Division Cycle protein that contains an anaphase-promoting complex (APC). This APC is involved in Cyclin degradation and promotes the movement of the cell out of mitosis. During the oneweek exposure to 30ppm nitrates, the growth rate of Tetrahymena cultures was determined using a hemocytometer. Furthermore, expression of the CDC16 gene was analyzed using semi-quantitative RT-PCR following the weeklong exposure. We predicted that a high concentration of nitrates would decrease the growth rate and expression of CDC16 in our Tetrahymena cultures.