DIGESTIVE PROCESS OF THE RAPTORIAL FEEDER CILIATE LITONOTUS-LAMELLA (RABDOPHORA, LITOSTOMATEA) VISUALIZED BY FLUORESCENCE MICROSCOPY

In this paper we present a fluorescence microscopy investigation of th e digestive process of Litonotus lamella, which we used as a prototype of the raptorial feeding behaviour. The sequence of its digestive pro cesses, from the capture of the prey (Euplotes crassus) to the formati on of digestive vacuoles was evidenced using Acridine Orange, a high q uantum yield fluorescent vital probe which has a great affinity with t he acid vesicle compartments. Acid vesicle localization and displaceme nt during digestion consisted of the following phases: in starved Lito notus vesicles were localized in the neck of the ciliate; after the ca pture, they were displaced around the vacuole containing the prey in e arly digestion, whereas in advanced digestion tens of digestive vacuol es containing Euplotes fragments were spread over the body of the pred ator Ih after capture, the digestive process was complete, and acid ve sicles reorganized in the neck of the predator. The most important fea ture we observed was that the digestive process occurred not in the si ngle phagosome as in filter feeder ciliates, such as Paramecium, but i n many digestive vacuoles scattered all over the predator cytoplasm, w hich asynchronously digest prey fragments. (C) 1997 Elsevier Science L td. All rights reserved.