Induction of a plasmodial stage of Physarum without plasmalemma invaginations.

Experimentally generated protoplasmic drops of Physarum show time-dependent differentiation processes, i.e. regeneration of plasmalemma, actomyosin fibrillogenesis and regeneration of the plasmalemma invagination system. According to Hatano (1970), caffeine treatment of drops results in a pinching off process of small translucent droplets in which specific effects of Ca++ on protoplasmic streaming phenomena were demonstrated. The light and electron microscopic investigation of the original drop reveal that the time-dependent differentiation processes, e.g. actomyosin fibrillogenesis, are not inhibited by caffeine. However, caffeine hinders the regeneration of the plasmalemma invaginations in the original drop (up to a drop age of 30--40 min). The experimental advantage of this stage of Physarum with full vitality, but without plasmalemma invaginations is discussed.