Cycloheximide Insensitive Amoebo‐Flagellate Transformation in Starved Amoebae of Physarum polycephalum (Physarum polycephalum/amoebo‐flagellate transformation/starvation/cycloheximide/protein synthesis)

The requirement of protein synthesis for amoebo‐flagellate transformation of Physarum polycephalum was re‐examined. When amoebae were grown on nutrient agar in association with live food bacteria and harvested in mid‐exponential phase of growth, it took ca. 2 hours for half the cells to form flagella after suspension in phosphate buffer. The transformation was completely inhibited by 5 μg/ml cycloheximide. To the contrary, when the amoebae in mid‐exponential phase were starved for 3 hr on non‐nutrient agar and then suspended in phosphate buffer, the duration required for this process was shortened to ca. 8 min and it was not inhibited by up to 100 μg/ml cycloheximide. A similar result was obtained using bactobolin, another inhibitor of protein synthesis. When amoebae were starved on non‐nutrient agar containing 5 μg/ml cycloheximide, however, the starvation effect described above was not observed. The results indicate that protein(s) necessary for the transformation might be synthesized during the starvation period, and that the amoebo‐flagellate transformation may or may not require concomitant protein synthesis depending upon preculture conditions.