Survey of Swimming Pattern Changes Associated With the Size of Cortical Inversions in Paramecium tetraurelia

Abstract

The cell surface of Paramecium tetraurelia is covered in cilia organized into approximately 70 ciliary rows which extend from the anterior of the cell to the posterior. One or more of these ciliary rows can be surgically rotated 180o in the local plane of the surface. These changes, known as cortical inversions, are heritable and produce rows of cilia which now have all of their anterior-posterior and left-right axes 180o-rotated from that of normally positioned rows. The power stroke of the cilia in the inverted rows is also rotated, which produces an altered swimming track of the cell. We generated and characterized a series of cell lines with different sizes of cortical inversions, from 0 rows (wild-type control), up to approximately 20 rows (maximum observed size). The swimming track of each cell line was recorded and quantitatively measured. We developed a mathematical formula relating the number of ciliary rows that are inverted to the geometric characteristics of the helical path traced by the cell as it swims.