Use of Thermal Denaturation Studies to Investigate the Base Sequence of Yeast Serine Srna.

29 Pollock, M. R., Biochim. Biophys. Acta, 76, 80 (1963). 30 Gross, P. R., and G. H. Cousineau, Biochem. Biophys. Res. Commun., 10, 321 (1963). 31 It should be emphasized that the liver contains a cell population heterogeneous with respect to cell type and rate of growth. 32 Nygaard, O., and H. P. Rusch, Cancer Res., 15, 240 (1955). 33 More exact estimates of turnover cannot be made in vivo with our present technique. The level of actinomycin D used by us not only inhibits cytoplasmic RNA labeling in rat liver, but also is lethal to the animal. It is apparent that in whole animal experiments measurements of turnover of messenger RNA are possible only in those tissues in which some decay of this fraction occurs before the antibiotic is fatal.