Incorporation of ribonucleic acid bases into the metabolic pool and RNA of E. coli.

Labeled cytosine, adenine, and guanine are rapidly incorporated by E. coli. A fraction of the radioactivity passes directly into RNA with very little delay. The remainder enters a pool before being incorporated into RNA. The fractions entering the pool and the time constants for equilibration of the specific activity of the pool are widely different for the four RNA bases.