@article{c1afddf081a04ceeac372c4206a67b5a,
title = "Differential Mutation Production by the Decay of Incorporated Tritium Compounds in Escherichia coli",
abstract = "We have studied the differential mutation production by the decay of incorporated tritium compounds in E. coli (WWU) using DNA-seeking precursors (H3-thymidine), RNA-seeking precursors (H3-uracil, H3-uridine), and protein-seeking precursors (H3-histidine, H3-proline). In particular we have determined the reversion frequency of an arginine locus. The reversion frequency is measured in units of revertants/surviving bacteria/H3 decay, and has an average value of 1.84 × 10-8 for H3-uridine and H3-uracil, 0.67 × 10-8 for H3-thymidine, and 0.28 × 10-8 for H3-proline and H3-histidine. Thus, the revertants are produced most effectively by H3 decays when the label is introduced in the form of an RNA precursor. The macromolecular distribution of the label shows that 5 to 8 per cent of the H3-uridine or H3-uracil is incorporated into DNA.",
author = "S. Person and Bockrath, {R. C.}",
note = "Funding Information: nism of H3 decay damage: (a) Tritium decay damage, both lethal and mutagenic, is entirely the result of ,8-particle radiation damage. Then, the lack of parallel between the reversion frequencies and the ldlling efficiencies requires that the vital centers for viability and arginine reversion have different locations in the bacterium. (b) Tritium decay damage, both lethal and mutagenic, is mediated in part by a local phenomenon at the site of the nuclide, and in part by ,8-particle radiation damage. It seems to us that the distribution of protein and RNA is similar in bacteria (Caro, 1962; Caro and Forro, 1962). Hence, the striking difference in the k values for RNA and protein would be interpreted as evidence favoring a local phenomenon. In the case of a local phenomenon, then the actual values for re-version frequencies would be expected to be different and would reflect the im- portance of the various labeled molecular species to the cell function examined. The data of Table II indicate that the incorporation of label from an RNA precursor label into DNA is of the order of 5 to 8 per cent. In another mutant of this strain we have reported an incorporation of 8 per cent (Person, 1963). Caro and Forro (1962) in still another mutant report 8 per cent. Since uridine will not fill the thymidine requirement, the incorporation of RNA precursor into DNA very likely occurs as a conversion of uracil or uridine to deoxycytosine or deoxycytidine. Chromatographic recovery of label in the position of cytosine from hydrolyzates of H3-uridine labeled cultures offers support for this conversion. The molecular species receiving H3-uridine or H3-uracil has been shown to be RNA and DNA. Thus, the existence of a local effect and the unexpectedly high reversion of the arginine locus by incorporated Hs-uridine or H3-uracil could refer to an RNA species intimately related to the replication of genetic information or to a cytosine {"}hot spot{"} in DNA. To suggest an actual mechanism by which an HI decay leads to an expressed revertant requires further understanding of the relation between the primary al- teration caused by the H3 decay and the final expression of this alteration in the produced revertant. Experiments are in progress to determine the nature of this relation. This research was supported by grants from the United States Public Health Service and by the National Aeronautics and Space Agency. It is always a pleasure to acknowledge discussions with Professor Ernest Pollard. In addition, we acknowledge discussion of our data with Mary Osborn, Brent Benson, Marshal Edgell, Frederick Funk, and Richard Wax. We sincerely ap- preciate the technical assistance of Miss Cora Jean Schaunberger. Received for publication, October 15, 1963.",
year = "1964",
doi = "10.1016/S0006-3495(64)86788-6",
language = "English (US)",
volume = "4",
pages = "355--365",
journal = "Biophysical journal",
issn = "0006-3495",
publisher = "Biophysical Society",
number = "5",
}