Alpha-mannosidase and Microcyst Differentiation in the Cellular Slime Mold Polysphondylium Pallidum

The intracellular and extracellular pattern of alpha-mannosidase (EC 3.2.1.24) activity was studied during microcyst differentiation in the cellular slime mold, Polysphondylium pallidum. The evidence suggests that microcyst differentiation requires continuous protein synthesis. alpha-Mannosidase activity is present in amoebae and increases with differentiation, and the data indicate that this increase in activity requires concurrent protein synthesis. The enzyme is excreted during the differentiation process, and the release of the enzyme is not stopped by cycloheximide. A cystless mutant does not show the normal intracellular pattern of alpha-mannosidase but does excrete the enzyme. Microcyst differentiation is proposed as an alternative system to multicellular slime mold development for the biochemical analysis of certain aspects of cellular differentiation.