Intracellular and extracellular enzyme patterns during microcyst germination in the cellular slime mold Polysphondylium pallidum

Abstract

Microcysts of Polysphondylium pallidum, formed in modified Sussman's (1963) medium, germinate synchronously without activation in 4 hr in a sterile nonnutrient medium. Germination is cycloheximide-sensitive only within the first 2 hr. In this early period, cycloheximide stops emergence of amoebae but does not prevent the initial swelling phase. Actinomycin D and nucleic acid analogs at high concentrations have no evident effects on the germination process. Of nine hydrolytic enzymes studied, only alkaline phosphatase shows a large intracellular increase in activity. The increase in activity is cycloheximide-sensitive, indicating a requirement for coincident protein synthesis. Additional experiments show the lack of activators or inhibitors of alkaline phosphatase activity at different stages of the germination process. Changes in the phosphatase isozyme population could not be detected and the enzyme is not excreted. Several lysosomal glycosidases show little change in intracellular activity but their activity increases dramatically in the extracellular medium. The extracellular increases in these enzymes correlate well with the morphological loss of the microcyst wall, suggesting a possible role for certain of these enzymes in wall digestion.