The effect of high ionic strength on the sedimentation properties of the biologically active component of bacterial ribonucleic acid.

1. The sedimentation properties of the fraction of bacterial RNA which stimulates the incorporation of amino acids into acid-insoluble material in vitro depend on the ionic strength of the sedimentation medium. 2. The different distributions of stimulatory activity found in centrifuged linear sucrose gradients loaded with bacterial RNA and containing 0.1m- or 0.6m-sodium chloride resemble closely the different sedimentation profiles of rapidly labelled RNA observed under the same conditions. 3. These findings agree with those of previous work of a similar nature (Willson & Gros, 1964) and demonstrate that the component of bacterial RNA preparations which stimulates the incorporation of amino acids into acid-insoluble peptides in vitro is contained in their rapidly labelled fraction.