Abstract
Membrane vesicles with a high mating reactivity were obtained from cilia of Paramecium caudatum by treatment with a solution containing 2 M urea and 0.1 mM Na2-EDTA. All processes of conjugation were induced in cells of the complementary mating type by approximately 10 mug/ml proteins of the vesicles. Electron microscope observation showed that the membrane vesicles have a diameter of 100-150 nm. Electrophoretic analysis on SDS polyacrylamide gel revealed no significant difference in polypeptide patterns of the particles from the two complementary mating types.