Acid Hydrolase Activity During Growth and Encystment in Acanthamoeba castellanii*

Abstract

The activity and sedimentation of acid phosphatase (APase), acid deoxyribonuclease (DNase), and acid ribonuclease (RNase) were investigated throughout growth and encystment in Acanthamoeba castellanii. The activities/mg protein of all 3 hydrolases are high in young cultures and decrease to constant levels in postlog cells. The RNase activity/ameba decreases 50% during growth, whereas the activity/cell of both APase and DNase remains constant. The percent sedimentation at 20,000 g of all 3 enzymes gradually increases from about 40% in midlog to a plateau of 80% in postlog cells. During encystment, the sedimentation behavior of RNase differs from that of APase and DNase. Encystment is characterized by a differential decrease in the activity/cell of the 3 hydrolases, with RNase decreasing most rapidly and APase least rapidly. APase is unique in that a transient increase of its specific activity is noted during encystment, even though its activity/cell is decreasing.

Changes in Two Acid Hydrolase Levels During Cyst Differentiation of a Ciliate, Histriculus muscorum1

“…A decrease in cellular content of several biological molecules (6,18,28) and the appearance of autophagic vacuoles (3, 7-9, 13, 16) have been described during cyst differentiation, both observations suggesting the participation of lysosomes in the process. The activity of lysosomal enzymes has been known to increase, transiently, during encystment of several soil amoebae (1, 10,12). Similar increases have been reported to occur in a cellular slime mold in conjunction with protein synthesis (20,21,23).…”

Phosphatase activity in the heterotrophic dinoflagellate Pfiesteria shumwayae

“…Autophagy is believed to occur in all eukaryotic cells and often increases during periods of cellular stress such as starvation (Dunn, 1994;Klionsky and Emr, 2000;Reggiori and Klionsky, 2002). Presumed autophagic vesicles containing acid phosphatase(s) have been detected in many protists (Elliott and Clemmons, 1966;Baker and Buetow, 1976;Martin and Byers, 1976;Swanson and Floyd, 1979). Acid phosphatase activity associated with possible autophagic vacuoles has been detected in the photosynthetic dinoflagellates, Alexandrium tamarense (Stein) Dodge and Lingulodinium polyedrum (Lebour) Balech (formerly Gonyaulax tamarensis and Gonyaulax polyedra, respectively; Schmitter and Jurkiewicz, 1981).…”

“…In contrast, phosphatase research on heterotrophic protists has focused on acid phosphatase localization in medically important parasites including Acanthamoeba castellanii (Douglas) Volkonsky (Wetzel and Korn, 1969;Martin and Byers, 1976;Ryter and Bowers, 1976) and the trypanosomatid flagellates Crithidia spp. (Brooker, 1971;McLaughlin et al, 1976), Leishmania spp.…”

Factors Regulating the Encystment Enhancing Activity (EEA) of Acanthamoeba castellanii

“…Amoebae growing in broth cultures were induced to encyst by addition of 2 pg berenil ml-I, by replacement of growth medium with Neffs inorganic encystment medium (NEM; Martin & Byers, 1976), or by replacement with glucose-free defined growth medium (GFDGM). In some cases, amoebae were transferred from broth to DGM-I 1 and grown for varying periods before glucose starvation.…”