Ref ID : 4289
Agnes K. Fok, Joanne H. Muraoka, and Richard D. Allen; Acid Phosphatase in the Digestive Vacuoles and Lysosomes of Paramecium caudatum: A Timed Study. J.Protozool. 31(2):216-220, 1984
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Enzyme cytochemistry was used to determine when acid phosphatase (AcPase) becomes associated with the digestive vacuoles (DVs) of axenically grown Paramecium caudatum that were pulsed with latex beads for 2-3 min. When cells were incubated in the Gomori medium. AcPase was not observed in the discoidal vesicles, the acidosomes, and the newly released DVs up to 3 min old or in most DVs 3-6 min old. The number of AcPase-positive DVs increased to 56% when DVs were 12-18 min old. Similar results were obtained using the napthol AS-TR phosphate-hexaotized rosanilin method at the light microscopic level where hundreds of DVs were scored though the maximal level of positive DVs obtained by this method was lower. In addition to DVs of specific ages, AcPase was found in ER, in some Golgi vesicles, and small vesicles similar in diameter to Golgi vesicles which may represent primary lysosomes in this ciliate. Larger vesicles abundant near the DV-II were only partially filled with reaction product. These vesicles, which could be identified by their paracrystalline sheets and a prominent glycocalyx lining the luminal surface of their membranes, fit the definition for secondary lysosomes. These results, which indicate that lysosomes fuse with DVs only after they have attained a certain age, suggest the existence of specific recognition factors on the membranes of secondary lysosomes as well as DV-II.