Developmental Regulation of Alkaline Phosphatase in Dictyostelium discoideum

Abstract

The kinetics of accumulation of alkaline phosphatase activity were determined in cells of wild-type and morphologically aberrant mutant strains of Dictyostelium discoideum induced to develop synchronously on membrane supports. The enzyme specific activity increased slowly in wild-type cells until culmination when a dramatic rise in specific activity occurred. The patterns of accumulation in the mutant strains, as well as previous electrophoretic analysis, suggest that the two phases of accumulation may result from the synthesis of distinct isozymes. The rapid accumulation of alkaline phosphatase was found to require concomitant protein synthesis. Ribonucleic acid synthesis, on the other hand, could be inhibited during the 8 hr immediately preceding culmination without affecting the amount of enzyme accumulated. When ribonucleic acid synthesis was inhibited earlier in development, the accumulation of alkaline phosphatase was reduced. Comparison of these results with work on other developmentally controlled enzymes suggests that both transcriptional and translational control occurs during development of D. discoideum . The accumulation of alkaline phosphatase was shown to require specific cellular topography during culmination, suggesting that intercellular interactions which allow synthesis of alkaline phosphatase occur at that stage.