Effect of salinity on food vacuole formation in T. thermophila

Abstract

Tetrahymena thermophila are ciliated protozoans typically found in freshwater ecosystems. Their primary method for food consumption is through phagocytosis which results in the formation of food vacuoles. The objective of this study was to determine if an increase in salinity affects the formation of food vacuoles in wildtype T. thermophila and low vac. T. thermophila mutants. Wildtype and mutant cultures were introduced to three treatment groups of varying sodium chloride concentrations (0mM, 2mM and 50mM). The formation of food vacuoles was followed in ten minute intervals for a total of 60 minutes. Every ten minutes, a sample of the treatment group was removed and fixed. Food vacuoles of five, randomly selected cells were counted using a compound microscope at 400X magnification. A mixed-effects two-way ANOVA test was performed and significance was found between food vacuole formation and the genotype of the organism (p-value=0.0003). As such, it was concluded that there is a difference between wildtype and mutant T. thermophila in food vacuole formation. No significance was found between salinity level and food vacuole formation. Additionally, no interaction was found between genotype and salinity that affected food vacuole formation. These results show that T. thermophila have the ability to withstand some changes to salinity levels in their environment. This may be important as climate and anthropogenic changes continue to affect freshwater ecosystems by increasing the salinity levels. Understanding the full extent of this ability may help us to predict the degree to which T. thermophila can continue to thrive alongside these changes to enhance freshwater ecosystems and support salmon.