Nucleic acids and protein metabolism in barley seedlings IV. Translocation of ribonucleic acids

Yeast [¹⁴C]RNA, [³H]RNA, [¹⁴C,³H]RNA have been shown to diffuse progressively through the seed into the coleoptile and the roots of germinating barley. The amount of RNA apparently translocated without appreciable degradation decreases with increasing age of the seedlings and with the increasing importance of their RNA metabolism. Polymerized RNA is better absorbed than digested RNA. All evidence is against any preliminary deep degradation and resynthesis (as shown by using doubly labelled RNA). The roots absorb much more RNA than does the coleoptile. The amount taken up represents a large part of the RNA which appears during a similar period of time of normal growth. The yeast RNA can be detected in the cytoplasm of coleoptile and root cells by autoradiography, and in their light-granules fraction by cytoplasm fractionation. Yeast RNA has an inhibitory action mainly on the root growth. It is suggested that cells might depend, for their macromolecules supply, on both endogenous and exogenous sources. The prevalence of translocation on metabolism could be dependent on physiological conditions.