Congruence of electrical properties in two Antarctic and two middle-latitude marine species of Euplotes (Ciliata, Hypotrichida)

Abstract

Electric membrane properties and motor behaviour of two Antarctic and two middle-latitude species of Euplotes were compared. Membrane potential fluctuations and whole-cell currents were measured using the whole cell clamp. The electrical properties of both of the Antarctic species between themselves and of both of the middle-latitude species are nearly identical. Furthermore, after warming up to 22 degrees C, the Antarctic species grown at 4 degrees C show the same pattern of spontaneous potential fluctuations, induced potential oscillations and membrane currents as the middle-latitude species grown and measured at 22 degrees C. After cooling down to 4 degrees C, the middle-latitude species grown at 22 degrees C show the same electrical properties as the Antarctic species grown and measured at 4 degrees C. The congruence of the temperature-dependent electrical properties in Euplotes species from completely different habitats is presumably based on a universal mechanism of temperature dependence of ionic conductances, indicating the close physiological relationship among the species.