Clustered genes for ribosomal ribonucleic acids in Escherichia coli

RNA/DNA hybridization experiments confirmed the existence of six genes for 23 s ribosomal RNA and six for 16 s ribosomal RNA for each Escherichia coli chromosome. The ability of nitrocellulose columns to separate pure from impure RNA/DNA hybrids led to the conclusion that most of the genes for ribosomal RNA are adjacent to each other.