Intracellular ribonuclease isozyme activity of the cellular slime mold cells, Dictyostelium discoideum Ax2 and Dictyostelium mucoroides

The isozymes of ribonuclease were analyzed in cell-free, crude extracts of cells by reversed activity staining of polyacrylamide gradient gels after e lectrophoresis. We previously reported three isozymes of the intracellular ribonuclease in Dictyostelium discoideum NC4, which were found in vegetativ e cells. In the present study, we examined the ribonucleolytic activity of an axenic strain of D. discoideum Ax2 cells which can grow with or without bacteria. The mobility of these isozymes (Dd I, II and III) was the same re gardless of the difference in the feeding condition. We also found the thre e isozymes of D. mucoroides cells, Dm I, II and III. Dm I was different fro m Dd I in D. discoideum cells, while Dm II and Dm III were the same as Dd I I and Dd III in terms of the mobility in polyacrylamide gradient gels durin g electrophoresis.