Centrosome and microtubules behavior in the cytoplasts.

After enucleation of PK (pig kidney embryo) cells using cytochalasin D centrioles remained approximately in 80% of cytoplasts. Some cytoplasts retained a single centriole. 14-16 h after enucleation large secondary lysosomes and lipid droplets were evident around the centrosome of many cytoplasts. In part of the cytoplasts replicating centrioles were found 16 h after enucleation. Ouabain treatment (1 mM, 30 min) of the cytoplasts resulted in the appearance of mainly perpendicular orientation of mother centrioles relative to the substrate surface. Reconstruction of microtubule pattern around the centrosome showed that a total of approximately 15 microtubules were attached in the centrosome of normal cells and twice more than that in cytoplasts. Microtubules in the cytoplasts were more resistant to nocodazole induced depolymerization. We suggest that microtubule instability is modulated by regulatory effector that is under direct nucleus control.