THE NUCLEAR ANNULI AS PATHWAYS FOR NUCLEOCYTOPLASMIC EXCHANGES

The Nuclear Annuli as Pathways for Nucleocytoplasmic Exchanges

Colloidal gold particles, 25 to 55 A in diameter, which had been coated with polyvinylpyrrolidone, were microinjected into the ground cytoplasm of amebas (Chaos chaos). At time intervals of 1 minute, 2 minutes, 10 minutes, and 24 hours after injection the cells were fixed for electron microscopy. After 24 hours, gold particles were found in both the nuclei and the ground cytoplasm, the concentr...

Binding within the Nuclear Annuli and Its Possible Effect on Nucleocytoplasmic Exchanges

Evidence exists which indicates that the pores of the nuclear envelope are important pathways for macromolecular exchanges between the nucleoplasm and cytoplasm (1-4). The pores as seen with the electron microscope often contain an electron-opaque material (5-7), and it has been suggested that the presence of such pore material could affect nucleocytoplasmic exchanges (8). Investigations in whi...

The Effect of the Electron-opaque Pore Material on Exchanges through the Nuclear Annuli

To investigate the extent to which the electron-opaque pore material can regulate nucleocytoplasmic exchanges which occur through the nuclear annuli, experiments were performed in which polyvinylpyrrolidone (PVP)-coated colloidal gold particles (25 to 170 A in diameter) were microinjected into the cytoplasm of amebas (Amoeba proteus). The cells were fixed at various times after injection and ex...

Nucleocytoplasmic Exchanges during Early Interphase

Colloidal gold was injected into the cytoplasm of amebae (Amoeba proteus) approximately 5 min, 1 hr, and 2 hr after cytokinesis. Later, interphase cells were similarly treated. All of the amebae were fixed about 50 min after injection and were examined with the electron microscope in order to determine the distribution of the gold. It was found that for a period of 2 hr after division the uptak...

Nucleocytoplasmic Exchanges during Cell Division