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.
Full text
PDF
Images in this article
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- CHENG P. Y. Evidence of the occurrence of u large RNA molecule per ribonucleoprotein particle. Biochim Biophys Acta. 1960 Jan 15;37:238–242. doi: 10.1016/0006-3002(60)90229-8. [DOI] [PubMed] [Google Scholar]
- FICQ A., PAVAN C., BRACHET J. Metabolic processes in chromosomes. Exp Cell Res. 1959;Suppl 6:105–114. [PubMed] [Google Scholar]
- GIERER A., SCHRAMM G. Infectivity of ribonucleic acid from tobacco mosaic virus. Nature. 1956 Apr 14;177(4511):702–703. doi: 10.1038/177702a0. [DOI] [PubMed] [Google Scholar]
- GOLDSTEIN L., MICOU J. On the primary site of nuclear RNA synthesis. J Biophys Biochem Cytol. 1959 Oct;6:301–304. doi: 10.1083/jcb.6.2.301. [DOI] [PMC free article] [PubMed] [Google Scholar] [Retracted]
- HARRIS H. Turnover of nuclear and cytoplasmic ribonucleic acid in two types of animal cell, with some further observations on the nucleolus. Biochem J. 1959 Oct;73:362–369. doi: 10.1042/bj0730362. [DOI] [PMC free article] [PubMed] [Google Scholar]
- LITTLEFIELD J. W., KELLER E. B., GROSS J., ZAMECNIK P. C. Studies on cytoplasmic ribonucleoprotein particles from the liver of the rat. J Biol Chem. 1955 Nov;217(1):111–123. [PubMed] [Google Scholar]
- WOODS P. S., TAYLOR J. H. Studies of ribonucleic acid metabolism with tritium-labeled cytidine. Lab Invest. 1959 Jan-Feb;8(1):309–318. [PubMed] [Google Scholar]