Minimum estimate of the lifetime of histone messenger RNA of HeLa cells

The lifetime of histone mRNA of HeLa cells has been studied by its kinetic of approach to steady-state labeling. Cells preincubated with low concentrations of actinomycin d to inhibit rRNA synthesis, were incubated with (3H)uridine. Linear incorporation of uridine was observed for only two hours under the conditions chosen. Polyribosomes were isolated from cells incubated overnight with trace amounts of (14C)uridine and for 30 to 150 min with (3H)uridine. RNA was extracted from polyribosomes and fractionated by polyacrylamide gel electrophoresis. Histone mRNA was identified as a peak migrating in a characteristic position, which was absent in gels of RNA obtained from cells treated with the inhibitor of DNA synthesis cytosine arabinoside. The kinetic of labeling of histone mRNA was linear up to 150 min, which represents a minimum estimate of the lifetime of this mRNA.