The contractile vacuole of Amoeba proteus. Some of the consequences of the microcoalescence hypothesis

Abstract

A simple model describing the contractile vacuole cycle in the freshwater protozoan Amoeba proteus is used to compute coalescence frequencies of submicroscopic vesicles needed to account for the growth of the vacuole. With this model, microvesicles were first considered as the source of volume and then as contributing the surface for the growing vacuole. Results show that vacuole growth by microvesicle accretion entails excessive fusion frequencies, thus generating a huge surplus of membrane. It is thus unlikely that microvesicle accretion is the only process involved in the growth of the contractile vacuole. On the other hand, vacuolar surface growth through vesicle accretion is much more plausible. The consequences of these facts are discussed.