The role of the nucleolus in the transfer of information from nucleus to cytoplasm

Abstract When the nucleus of a hen erythrocyte is introduced into the cytoplasm of a human or mouse cell in culture, it resumes the synthesis of RNA (Harris 1965, 1967). The reactivated erythrocyte nucleus undergoes great enlargement, but it does not, for at least 2 or 3 days, develop nucleoli. During this period, the heterokaryon, although it may contain active erythrocyte nuclei, does not synthesize any hen-specific surface antigens. But when, later, the erythrocyte nuclei do develop nucleoli, hen-specific antigens reappear on the surface of the heterokaryon and progressively accumulate. These and other nucleolar inactivation experiments suggested that the nucleolus may play a decisive role in the transfer of information from the nucleus to the cytoplasm (Harris et al. 1969; Sidebottom and Harris 1969; Deak et al. 1972; Harris 1972).