[The behavior of nucleolar proteins under the conditions of the reversible three-dimensional separation of the structural components of the nucleolus].

The intracellular localization of Ag-proteins and protein B23 has been studied under the action of a low ionic strength solution (20% Hank's solution) on living pig cultured kidney cells (PK). For this, Ag-staining of nucleoli and indirect immunofluorescence using antibodies against B23 were applied. It has been shown that incubation of living cells in diluted Hank's solution results in migration of B23 from nucleoli to the nucleoplasm. A lot of Ag-proteins also migrate into the nucleoplasm, while part of them remained bound with the nucleolar remnants. Such a relocation of B23 was found to be completely reversible, and if hypotonic medium was replaced by the complete one, the nucleoli were able to reappear again, and B23 was detected solely within them. Fusion of prenucleolar bodies with reconstructing nucleoli could be delayed by cell incubation with actinomycin D. Generally, the process of nucleolar reconstitution following their artificial disorganization in hypotonic medium was believed to be similar to the nucleologenesis observed during normal mitosis. Light hypotonic treatment of living cells facilitates the evaluation of the number of silver grains over nucleoli due to their less compact arrangement than in the control.