The Experimental Organism

Photo Courtesy of Emily Balf '05'

Tetrahymena pyriformis is a ciliated protist that can be used to investigate the effects of cigarette extracts on ciliary function. The cilia lining human lungs and those on the surface of Tetrahymena are structurally similar. In Tetrahymena, rows of cilia cover the surface of the cell. The integrated, alternate bending of the cilia creates the spiral swimming pattern seen when the animal is viewed under a microscope. It also creates currents that move food particles into the mouth, or cytostome, which appears as a slight depression on the upper left side of the photograph. The animal was photographed using a microscope at 600X. It was "fed" particles of India ink. As the animal fed, the ink particles were collected in food vacuoles that appear as dark spheres inside the cell. By counting the number of vacuoles formed per unit time, it is possible to determined the rate of food vacuole formation. Click here to view the cilia of a related species of Tetrahymena, T. termophilia. The image was taken on a confocal microscope at 1500X. Substances that inhibit ciliary action should also inhibit feeding and the rate of food vacuole formation. For this reason, Tetrahymena can be used to study of the effects of potentially toxic substances on ciliary action. Preparation of cigarette extracts.