Zellfunktionen und zellfunktionswechsel in der entwicklung von Dictyostelium discoideum: VI. Inhibitoren der aggregation, ihr einfluss auf zellkontaktbildung und morphogenetische bewegung

Abstract

Inhibition of cell aggregation by 2,4-dinitrophenol (DNP), 2-mercaptoethanol (MCAe) and urethan was tested with amoeba cells of Dictyostelium discoideum. The following inhibitory effects on aggregative cell movements and intercellular contacts have been observed. 1. 1. All substances tested inhibit aggregation by inhibition of cell movement. 2. 2. Moreover, DNP reversibly interferes with the activity of contractile vacuoles and with protoplasmic streaming; cells in any developmental stages are sensitive. Since similar effects can be produced by anaerobic conditions, it is concluded that in the material used in these experiments, oxidative phosphorylations are indispensable for fundamental cellular functions. Thus, DNP has not a specific action as an inhibitor of aggregation. 3. 3. MCAe action also yields the cells spherically, but the other characteristic effects of DNP are not observed. It is assumed that MCAe among others acts on the cell membrane directly. 4. 4. Formation of intercellular contacts is not reduced drastically by DNP; cell substrate contacts, on the contrary, are inhibited (nearly) completely. 5. 5. MCAe considerably weakens the non phase-specific intercellular contacts which are characterized by high EDTA-sensitivity. The cell binding specific for cells in the aggregation stage is reduced but little by MCAe. It is noticed that the cellular basis of Dictyostelium development in some respects is quite similar to that of more complicated developmental systems in animals.