Cathodal Galvanotaxis: The Effect of Voltage on the distribution of Tetrahymena pyriformis

Tetrahymena pyriformis are unicellular eukaryotes with thousands of hair-like structures called cilia on the surface of their bodies that aid in cell motility and food consumption. The similarities between their cilia and that of humans, particularly in the human respiratory and olfactory track, are why they are model organisms for investigating cell movement and cilia functionality. Further research may help scientists better understand how cilia are affected by common ciliopathies, genetic disorders caused by the abnormal formation or function of cilia. The objective of this experiment was to investigate the effect of voltage on the distribution of T. pyriformis across a capillary tube. T. pyriformis-filled capillary tubes were connected to a power supply for one minute. We calculated the percent distributions at the anode and cathode of the capillary tube by counting T. pyriformis with a hemocytometer. Our results indicate that cathodal galvanotaxis is induced at 4V and that, despite increases in voltage from 4–30V, the percent distribution of T. pyriformis at the cathode remained constant at approximately 80%. These data suggest that while calcium and potassium voltage-gated ion channels are mediated by graded potentials and are triggered at specific thresholds, further increasing voltage above that threshold had little effect.