Silver staining and nucleolar patterns in human heteroploid and measles-carrier cells.

Abstract

Silver staining revealed 10, 11 and 7 active rDNA sites (Ag-NORs) in acrocentrics of human diploid fibroblasts, near-triploid Lu106 cells (a HeLa-derivative) and measles-carrier Lu106 cells, respectively. Thus, the heteroploid cell lines showed no significant increase in Ag-NORs. They also had consistent Ag-staining patterns, in accordance with their karyotypic uniformity. The numbers of Ag-NORs agreed with the numbers of acrocentrics present. The fewer Ag-NORs in the measles-carrier cells showed increase of the Ag-stained material indicating regulated ribosomal gene activity. Similarly, in interphase cells stained with toluidine blue, the nucleoli were fewer but larger in the measles-carrier cells. By combining Ag-staining and G-banding in control and measles-carrier Lu106 cells, it was possible to identify the Ag-positive acrocentrics. These included normal and marker chromosomes. In both cell lines. Ag-positive chromosomes No. 15 were frequent. Numbers and sizes of nucleoli at anaphase, telophase and early interphase in monolayers corresponded to the Ag-staining patterns in air-dried metaphases. Thus, silver-stained regions in the metaphase chromosomes develop and grow into larger nucleoli during interphase. Ag-staining of some interphase nuclei in the measles-carrier cells comprised materials other than those found at the primary NORs.