Analysis of an inducer of the amoebal-plasmodial transition in the myxomycetes Didymium iridis and Physarum polycephalum.

Recent studies with amoebae of the Myxomycetes Didymium iridis and Physarum polycephalum reveal that competence to undergo sexual fusion or to differentiate to plasmodia apogamically can be induced by a diffusible factor. Suspension cultures of Didymium amoebae have proven to be a good source of the inducer activity. Cell-free culture supernatants accelerated mating of Didymium and Physarum amoebae and also apogamic differentiation of the Physarum strain Colonia . Characterization and purification of the inducer activity is being conducted with a semiquantitative bioassay based on the induction of zygote formation in suspensions of mating-compatible Didymium amoebae.