CONGRUENCE OF ELECTRICAL-PROPERTIES IN 2 ANTARCTIC AND 2 MIDDLE-LATITUDE MARINE SPECIES OF EUPLOTES (CILIATA, HYPOTRICHIDA)

Electric membrane properties and motor behaviour of two Antarctic and two middle-latitude species of Euplotes were compared. Membrane potent ial fluctuations and whole-cell currents were measured using the whole cell clamp. The electrical properties of both of the Antarctic specie s between themselves and of both of the middle-latitude species are ne arly identical. Furthermore, after warming up to 22 degrees C, the Ant arctic species grown at 4 degrees C show the same pattern of spontaneo us potential fluctuations, induced potential oscillations and membrane currents as the middle-latitude species grown and measured at 22 degr ees C. After cooling down to 4 degrees C, the middle-latitude species grown at 22 degrees C show the same electrical properties as the Antar ctic species grown and measured at 4 degrees C. The congruence of the temperature-dependent electrical properties in Euplotes species from c ompletely different habitats is presumably based on a universal mechan ism of temperature dependence of ionic conductances, indicating the cl ose physiological relationship among the species.