Biophysical Journal 2: 465-482 (1962)
© 1962 the Biophysical Society

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Cheng, P.-Y. Search for Related Content PubMed PubMed Citation Articles by Cheng, P.-Y.

Sedimentation and Autoradiographic Analyses of Rapidly Labeled Ribonucleic Acids in Human Amnion Cells

ABSTRACT

When human amnion cells were exposed to radioactive cytidine for 0.002 or 0.017 of one generation time, the alcohol-insoluble label in the RNA preparations from these cells was distributed between a rather homogeneous component of 4 to 8S and a fast mixture of 34S, 30S, 25S, 20S, and 15S. Evidence has been presented that these sedimenting components are RNA. More than 73 per cent of the label in the fast mixture from the cells labelled for 0.017 of one generation time was derived from the nuclei. The label in nucleotides after 0.017 of one generation time equaled 1.4 times that in RNA. Thus, the previous autoradiographic evidence for the nuclear origin of late cytoplasmic label is weak. The distribution of label among the various sedimenting components, as well as that between two pyrimidine nucleotide constitutents of 34S, 30S, 25S, and 15S components, changed when the length of exposure to radioactive cytidine was increased from 0.002 to 0.017 of one generation time. This result excluded the possibility that the population of the RNA labeled after 0.002 of one generation time was identical with that labeled later. This fact must be included in formulation of hypotheses for the function of rapidly labeled RNA's.

This article has been cited by other articles:

				T. Staehelin, F. O. Wettstein, and H. Noll Breakdown of Rat-Liver Ergosomes in vivo after Actinomycin Inhibition of Messenger RNA Synthesis Science, April 12, 1963; 140(3563): 180 - 183. [Abstract] [PDF]