Metabolic patterns and nutritional effects on differentiation (sclerotization) in the Myxomycete, Physarum flavicomum

The subject of this research endeavor is the determination of the nutritional effects and biochemical events associated with the differentiation (sclerotization) of the Myxomycete Physarum flavicomum variety 1. During this differentiation process, the formerly growing, naked, acellular plasmodium converts into numerous dormant cells surrounded by cell walls. It has been generally assumed that starvation conditions are necessary for the induction of differentiation. This work, however, establishes that, not complete starvation, but a condition of nutrient imbalance triggers the differentiation process. That is, the unavailability of an adequate spectrum of amino acids in the medium initiates the myriad of metabolic and morphological alterations characteristic of the sclerotizing plasmodium. In the absence of extracellular amino acids, cellular amino acids and cellular protein are catabolized, thereby diminishing these cell fractions, and sclerotization proceeds. However, in the presence of extracellular amino acids, sclerotization is delayed, and the amino acid content of the soluble pool and protein content of the incubating cells are comparable to those of the respective fractions of plasmodia under normal growth conditions. [...]