Sporulation delay by stable cAMP analogues in the slime moldPhysarum polycephalum.

Plasmodial cells of the slime moldPhysarum polycephalum become competent for sporulation following a prolonged period of starvation in darkness. Then sporulation can be induced by illumination. Microinjections of the stable (Sp)- and (Rp)-diastereoisomers of adenosine cyclic 3',5' monothionophosphate before and during a sensitive period from the start of illumination until 5 h after lead to a significant delay in the sporulation process.

RNA transcription of isolated nuclei and chromatin with exogenous RNA polymerases during mitotic cycle and encystment ofPhysarum polycephalum.

Nuclei have been isolated from plasmodia ofPhysarum. Chromatin has been prepared from these nuclei by lysing them gently with lysolecithin. Both nuclei and chromatin contain endogenous activities of RNA polymerases A and C but not of RNA polymerase B under the conditions specifiied.

Discrimination of potential and actual RNA polymerase B activity in isolated nuclei during differentiation ofPhysarum polycephalum.

Isolated nuclei ofPhysarum contain endogenous RNA polymerase activity. We provide evidence for four different states of RNA polymerase B: 1. free enzyme (85%); 2.

Levels of RNA polymerase activities during growth, encystment and germination ofPhysarum polycephalum.

Two RNA polymerases, enzyme A and enzyme B, were prepared fromPhysarum plasmodia. They are not located in the cytosol. Isolated nuclei, however, contain only a fraction of the total RNA polymerase activity: 1.