Abstract
The killing efficiency of tritium disintegrations in frozen mammalian cells labeled with tritiated uridine, histidine, and lysine was compared with the killing efficiency of incorporated tritiated thymidine. In each case, the distribution of tritium in the cells was determined by chemical fractionation as well as by radio-autography. Of all tritium disintegrations, by far the most effective were those occurring in DNA molecules within frozen cells; such incorporated tritium has a killing efficiency of 0.006. When cells were incubated with tritiated uridine for 10 min to label nuclear RNA, the killing efficiency was 0.0015. When the cells were pulse labeled with tritiated uridine and permitted to grow in nonradioactive media for 10 hr before freezing in order to incorporate tritium into cytoplasmic RNA, the killing efficiency was reduced to 0.0010. The results suggest that decay of tritium in nuclear RNA is more effective than that in cytoplasmic RNA. When the cells were labeled with tritiated histidine or lysine for 30 min, tritium atoms were found mainly in the acid soluble rather than in the protein fraction and the killing efficiency in each case was approximately 0.0007. The results of these suicide experiments indicate that the killing efficiency of tritium disintegrations depends on where tritium is located within the cells. Tritium disintegrations in the nucleus are more effective in killing the cell than that in cytoplasm; and tritium disintegrations on DNA in the nucleus is more effective in killing the cell than that of nuclear RNA.
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- ALEXANDER P., MIKULSKI Z. B. Differences in the response of leukaemia cells in tissue culture to nitrogen mustard and to dimethyl myleran. Biochem Pharmacol. 1961 Feb;5:275–282. doi: 10.1016/0006-2952(61)90018-1. [DOI] [PubMed] [Google Scholar]
- DEWEY W. C., HUMPHREY R. M., CORK A. COMPARISON OF CELL-MULTIPLICATION AND COLONY-FORMATION AS CRITERIA FOR RADIATION DAMAGE IN CELLS GROWN IN VITRO. Int J Radiat Biol Relat Stud Phys Chem Med. 1963 May;6:463–471. doi: 10.1080/09553006314550551. [DOI] [PubMed] [Google Scholar]
- DEWEY W. C., HUMPHREY R. M., JONES B. A. COMPARISONS OF TRITIATED THYMIDINE, TRITIATED WATER, AND COBALT-60 GAMMA RAYS IN INDUCING CHROMOSOMAL ABERRATIONS. Radiat Res. 1965 Feb;24:214–238. [PubMed] [Google Scholar]
- FISCHER G. A., SARTORELLI A. C. DEVELOPMENT, MAINTENANCE AND ASSAY OF DRUG RESISTANCE. Methods Med Res. 1964;10:247–262. [PubMed] [Google Scholar]
- GUDE W. D., UPTON A. C., ODELL T. T., Jr Giemsa staining of autoradiograms prepared with stripping film. Stain Technol. 1955 Jul;30(4):161–162. doi: 10.3109/10520295509114458. [DOI] [PubMed] [Google Scholar]
- PERSON S., BOCKRATH R. C., Jr DIFFERENTIAL MUTATION PRODUCTION BY THE DECAY OF INCORPORATED TRITIUM COMPOUNDS IN E. COLI. Biophys J. 1964 Sep;4:355–365. doi: 10.1016/s0006-3495(64)86788-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Person S. Comparative Killing Efficiencies for Decays of Tritiated Compounds Incorporated into E. coli. Biophys J. 1963 May;3(3):183–187. doi: 10.1016/s0006-3495(63)86814-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
- RACHMELER M., PARDEE A. B. Loss of viability and beta-galactosidase-forming ability as a consequence of tritium decay in Escherichia coli. Biochim Biophys Acta. 1963 Jan 29;68:62–67. doi: 10.1016/0006-3002(63)90111-2. [DOI] [PubMed] [Google Scholar]
- Watanabe I., Okada S. Effects of temperature on growth rate of cultured mammalian cells (L5178Y). J Cell Biol. 1967 Feb;32(2):309–323. doi: 10.1083/jcb.32.2.309. [DOI] [PMC free article] [PubMed] [Google Scholar]