Ultrastructural localization of phosphatases with cerium in a ciliated protozoan.

Abstract

Acid phosphatase (AcPase) and thiamine pyrophosphatase (TPPase) have been detected with cerium as a capture agent for the first time in ciliated protozoa. In the trophozoites of the parasitic ciliate Ichthyophthirius multifiliis, AcPase activity was previously reported in food vacuoles, primary lysosomes, golgian-like cisternae and in some alveolar sacs. These former results obtained by lead methods, have now been confirmed and improved by a cerium-based technique. TPPase activity was also observed in golgian-like cisternae and alveolar sacs. As the cell membrane of this ciliate proved to be highly impermeable to cerium ions, several hr of preincubation in buffer with cerium chloride and Triton X-100 were needed to detect phosphatases with cerium in intact ciliates. However, in sectioned ciliates the preincubation time could be greatly reduced. Since TPPase became inhibited after a long preincubation, it could only be detected with cerium in sectioned ciliates.