SPECIES SPECIFICITY OF LOW MOLECULAR WEIGHT NUCLEAR RNAS

1. 1. The low molecular weight monodisperse nuclear RNA species previously characterized in HeLa cells are found in a number of vertebrate tissue culture lines. They are compared by co-electrophoresis on polyacrylamide gels of labeled RNA from isolated nuclei or subnuclear fractions. 2. 2. Seven low molecular weight RNA species were found in nuclei of the 3T3 line of mouse fibroblasts; each of them corresponds in intranuclear localization and approximate electrophoretic mobility to one of the seven species in HeLa cells. However, the precise mobilities of three of the species are different in 3T3 and HeLa cells. 3. 3. The electrophoretic patterns of RNA from L cells (another line of mouse fibroblasts) and 3T3 cells are identical, while those from WI38 cells (a line of diploid, non-malignant human fibroblasts) are indistinguishable from those of HeLa cells. Thus the mobility of the respective RNA species is determined by the animal of origin, and not by the cell type, karyotype, or tumororigenicity of the cells. 4. 4. There is a slight difference between mouse and hamster cells with respect to the mobility of one RNA species. 5. 5. The low molecular weight nuclear RNA species are present in cells of amphibians, as well as birds and mammals. © 1969.