Analysis of prefission morphogenesis inParamecium aurelia

摘要: Paramecium aurelia has been exposed to varying concentrations of actinomycin D for extended periods and a high concentration starting at various specific times in the cell cycle. Extended exposures 5 μg per 1.0 ml culture medium are lethal as 24 hour 20 μ/1.0 ml. Exposures initiated selected interfission period reveal transition stabilization points, similar those found Tetrahymena, that is, exposure prior point almost invariably blocks given developmental event. Exposure after may or not result blockage but typically never shows blockage. Also normal sequence events can be upset by actinomycin. These results interpreted being consistent with sequential action genes cycle indicating independence final genetic control different processes, though all processes dependent on common events. The macronucleus cells aggregation dark material is neither DNA nor RNA, probably protein, whose function known.