Effect of an electric field on the motility of Entamoeba histolytica examined by multiple-beam interference microscopy

A recently developed multiple-beam interference microscopic technique has been used to visualize submicroscopic structures of Entamoeba histolytica and their movements in applied external electric fields. The movements were videorecorded and it was found that at low current (120 microA) pseudopods are filled with hyaline ectoplasm. At slightly higher current (about 150 microA), the amoeba stops extending the pseudopods and loosens its attachment to the surface. At higher currents (200 microA), it forms a cyst and remains immobile for a time. Before this stage is reached a narrow ring is formed around the nucleus due to alterations in the proteins to protect it.