Nucleotide sequences within the ribosomal ribonucleic acids of HeLa cells, Xenopus laevis and chick embryo fibroblasts.

Nucleotide sequences within the ribosomal RNAs of HeLa cells, Xenopus laevis cultured kidney cells and chick embryo fibroblasts were compared by “finger-fprinting” procedures, using separate preparations of ³²PO₄-labelled and [¹⁴C] methyl-labelled RNAs. The results revealed extensive similarities between oligonucleotides from the ribosomal RNAs of the three species, and also some characteristic interspecies differences. The following findings were of particular interest.