Temperature dependence of heat-induced spherulation of slime mold Physarum polycephalum

Microplasmodial cells of slime mold Physarum polycephalum grown in liquid culture showed differentiation into spherules when incubated at 3–5 °C higher than the upper limit temperature for normal growth. The optimal condition for spherule induction was continuous shaking at 36–38 °C for 24 h in the dark with a semi-defined medium. The spherules thus formed were viable, as revealed by their capability of growing into microplasmodia when transferred into a fresh medium and shaken at 25 °C.