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Amato P, Doyle SM, Battista JR, Christner BC. Implications of subzero metabolic activity on long-term microbial survival in terrestrial and extraterrestrial permafrost. ASTROBIOLOGY 2010; 10:789-798. [PMID: 21087159 DOI: 10.1089/ast.2010.0477] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The survival of microorganisms over extended time frames in frozen subsurface environments may be limited by chemical (i.e., via hydrolysis and oxidation) and ionizing radiation-induced damage to chromosomal DNA. In an effort to improve estimates for the survival of bacteria in icy terrestrial and extraterrestrial environments, we determined rates of macromolecular synthesis at temperatures down to -15°C in bacteria isolated from Siberian permafrost (Psychrobacter cryohalolentis K5 and P. arcticus 273-4) and the sensitivity of P. cryohalolentis to ionizing radiation. Based on experiments conducted over ≈400 days at -15°C, the rates of protein and DNA synthesis in P. cryohalolentis were <1 to 16 proteins cell(-1) d(-1) and 83 to 150 base pairs (bp) cell(-1) d(-1), respectively; P. arcticus synthesized DNA at rates of 20 to 1625 bp cell(-1) d(-1) at -15°C under the conditions tested. The dose of ionizing radiation at which 37% of the cells survive (D(37)) of frozen suspensions of P. cryohalolentis was 136 Gy, which was ∼2-fold higher (71 Gy) than identical samples exposed as liquid suspensions. Laboratory measurements of [(3)H]thymidine incorporation demonstrate the physiological potential for DNA metabolism at -15°C and suggest a sufficient activity is possible to offset chromosomal damage incurred in near-subsurface terrestrial and martian permafrost. Thus, our data imply that the longevity of microorganisms actively metabolizing within permafrost environments is not constrained by chromosomal DNA damage resulting from ionizing radiation or entropic degradation over geological time.
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Affiliation(s)
- Pierre Amato
- Louisiana State University, Department of Biological Sciences, Baton Rouge, Louisiana 70803, USA
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Wagner S, Snipes W. Effects of acridine plus near-ultraviolet light on the outer membrane of Escherichia coli. Photochem Photobiol 1982; 36:255-8. [PMID: 6750667 DOI: 10.1111/j.1751-1097.1982.tb04373.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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3
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Wagner S, Feldman A, Snipes W. Recovery from damage induced by acridine plus near-ultraviolet light in Escherichia coli. Photochem Photobiol 1982; 35:73-81. [PMID: 7043500 DOI: 10.1111/j.1751-1097.1982.tb03813.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Wagner S, Taylor WD, Keith A, Snipes W. Effects of acridine plus near ultraviolet light on Escherichia coli membranes and DNA in vivo. Photochem Photobiol 1980; 32:771-9. [PMID: 7005916 DOI: 10.1111/j.1751-1097.1980.tb04054.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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5
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Pollack A, Bagwell CB, Irvin GL, Jensen JA. The kinetics of the formation of a G2 block from tritiated thymidine in phytohemagglutinin-stimulated human lymphocytes. CYTOMETRY 1980; 1:57-64. [PMID: 7273963 DOI: 10.1002/cyto.990010112] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Flow cytometry (FCM) was used to monitor the radiation effects promoted by incorporated tritiated thymidine (3H-TdR) on phytohemagglutinin (PHA)-stimulated human peripheral blood lymphocytes stained with propidium iodide (PI). Lymphocyte microcultures were continuously labeled or pulse-labeled for various periods of time with different 3H-TdR concentrations. Two types of DNA histogram analyses were performed on unperturbed and 3H]TdR perturbed lymphocytes. The data analyses consisted of statistical analyses between averaged groups of histograms (nonparametric analysis) and cell cycle analyses (parametric analysis) to determine the percentages of cells in G0 + G1, S and G2 + M. The results showed that (a) 3H-TdR when added to proliferating lymphocytes under certain conditions (both short-term continuous and pulse-labeling) caused a highly significant increase in the proportion of tetraploid (4C) cells by FCM, (b) the increase in the proportion of 4C cells represented a block in G2 and (c) the relative increase in the percentage of 4C cells was proportional to 3H-TdR incorporation which was proportional to labeling time and concentration. Therefore, it was concluded that short labeling times be used to minimize adverse radiation effects when 3H-TdR is used to assay substances affecting lymphocyte proliferation or in the estimation of cell cycle time.
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Gupta RS, Siminovitch L. Genetic markers for quantitative mutagenesis studies in Chinese hamster ovary cells: characteristics of some recently developed selective systems. Mutat Res 1980; 69:113-26. [PMID: 6987491 DOI: 10.1016/0027-5107(80)90181-5] [Citation(s) in RCA: 73] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Selection conditions have been optimized in the Chinese hamster ovary (CHO) cell system for a number of genetic markers. The genetic systems studied include resistance to the protein-synthesis inhibitors emetine (Emtr) and diphtheria toxin (Dipr), resistance to methylglyoxalbisguanylhydrazone (Mbgr) which affects polyamine transport, resistance to the nucleoside analogs toyocamycin and tubercidin (Toyr), and resistance to thioguanine (Thgr) and ouabain (OuaR). The optimal expression time following mutagenesis for various markers was between 2 and 6 days. A linear dose--response relationship between the concentration of mutagen (ethyl methanesulfonate) and mutation frequency has been observed over the range of 10--700 micrograms/ml, for all of the above markers except Toyr. The response of these markers to other mutagens such as tritium (3H) decay and ICR-191 show some specificity. Since the response of a number of genetic markers can be studied simultaneously in the CHO system, it should prove very useful for studies of quantitative mutagenesis and in assay systems for mutagen detection.
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Feinendegen LE, Cronkite EP, Bond VP. Radiation problems in fusion energy production. RADIATION AND ENVIRONMENTAL BIOPHYSICS 1980; 18:157-183. [PMID: 7005925 DOI: 10.1007/bf01323596] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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Pollack A, Bagwell CB, Irvin GL. Radiation from tritiated thymidine perturbs the cell cycle progression of stimulated lymphocytes. Science 1979; 203:1025-7. [PMID: 424727 DOI: 10.1126/science.424727] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Tritiated thymidine was found to affect the cell cycle progression of phytohemagglutinin-stimulated human lymphocytes. By means of flow cytometry a statistically significant increase in the G2 and M phases of the cell cycle was observed in cultures with low concentrations of tritiated thymidine added 18 hours before the cultures were harvested.
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Abstract
The effect of nitrous acid (NA) on viability, integrity of cellular DNA and on membrane transport were studied in 5 strains of Escherichia coli. Stationary phase cells, grown on mineral salts medium, were exposed to NA. The viability of strains decreased in thefollowing order: W3110 wild-type greater than WP2 wild-type, WP2 uvrA greater than NG30 recA greater than P3478 polA. Alterations were found in the DNA sedimentation profile in alkaline sucrose gradient. Disturbance of DNA synthesis was measured by 3H-labelled thymidine ([3H]Thd) incorporation. No degradation of DNA was found after NA treatment. Low doses of NA caused significant inhibition of leucine and glucose transport into whole cells. The results are interpreted in terms of the multi-target action of NA causing the death of cells.
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Krasin F, Person S, Snipes W, Benson B. Local effect for (5-3H)cytosine decays: production of a chemical product with possible mutagenic consequences. J Mol Biol 1976; 105:445-51. [PMID: 787538 DOI: 10.1016/0022-2836(76)90103-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Person S, Snipes W, Krasin F. Mutation production from tritium decay: a local effect for (3H)a-adenosine and (3H)6-thymidine decays. Mutat Res 1976; 34:327-32. [PMID: 765811 DOI: 10.1016/0027-5107(76)90137-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Person S, McCloskey JA, Snipes W, Bockrath RC. Ultraviolet mutagenesis and its repair in an Escherichia coli strain containing a nonsense codon. Genetics 1974; 78:1035-49. [PMID: 4616874 PMCID: PMC1213237 DOI: 10.1093/genetics/78.4.1035] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Ultraviolet mutagenesis and its repair were studied mainly in WU36-10-89, a uvr(-) strain of Escherichia coli containing a UAG mutation in a gene for leucine biosynthesis. Following ultraviolet (UV) irradiation revertants appearing with or without direct photoreactivation (PR) were classified according to the presence and type of suppressor they contained. We find UV mutation production to be quite specific. An analysis of revertants produced by UV indicates they are formed mainly from GC --> AT and that the miscoding is due to a cytosine residue at the site of mutation in a cytosine-thymine (CT) dimer. We propose that the dimer serves as template during some aspects of repair replication and at the time of replication the C in the dimer directs the insertion of A in the complementary strand. We also note that C --> A and T -->G changes caused by a CT dimer occur much less frequently.
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Lundbäck AK, Nordström K. Mutations in Escherichia coli K-12 decreasing the rate of streptomycin uptake: synergism with R-factor-mediated capacity to inactivate streptomycin. Antimicrob Agents Chemother 1974; 5:500-7. [PMID: 4618460 PMCID: PMC429002 DOI: 10.1128/aac.5.5.500] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Escherichia coli K-12 carrying the R-factor R1 or R6K is resistant to streptomycin. The resistance is due to R-factor-coded enzymes that metabolize the drug. Streptomycin can be inactivated in two ways, either by adenylylation or by phosphorylation; both reactions require adenosine 5'-triphosphate. In this work we show that the R-factor R1 codes for an enzyme that adenylylates streptomycin and that the enzyme activity is located in the periplasmic volume, whereas the R-factor R6K codes for a streptomycin phosphorylase, which is mainly cytoplasmic. From a strain without any R-factor or carrying different R-factors, mutants were isolated that are 10 times more resistant to streptomycin than the parent strains. This increased resistance is not due to increased amounts of metabolizing enzymes. The mutants have a decreased rate of uptake of streptomycin and an altered response to other antibacterial agents as well. The mutations are located on the chromosome and not on the plasmid. It is likely that the mutations cause changes in the outer layers of the cell envelope and that the increased resistance is due to the synergistic effect of an efficient penetration barrier and a low activity of inactivating enzyme.
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Sclair M, Edgell MH, Hutchinson CA. Mapping of new Escherichia coli K and 15 restriction sites on specific fragments of bacteriophage phi X174. J Virol 1973; 11:378-85. [PMID: 4570925 PMCID: PMC355113 DOI: 10.1128/jvi.11.3.378-385.1973] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
We have isolated several new phiX174 mutants which contain sites sensitive to restriction by Escherichia coli. One contains an E. coli 15 restriction site and three are double mutants containing an E. coli K site as well as the E. coli 15 site. The replicative form (RF) DNA of one of the mutants containing a K site has been shown to be restricted in spheroplasts of a K-12 strain. The infectivity of this RF, but not wild-type RF, has also been shown to be inactivated by an E. coli K extract and by purified K restriction enzyme in vitro. The product of the RF treated with purified K restriction enzyme in vitro is a full length linear molecule. The mutant sites have also been localized to specific regions of the phiX174 genome by a fragment mapping technique, making use of specific fragments of phiX174 RF DNA obtained by digestion with a specific endonuclease.
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Phillips SL, Person S, Newton HP. Characterization of genetic coding changes in bacteria produced by ionizing radiation and by the radioactive decay of incorporated 3 H-labelled compounds. INTERNATIONAL JOURNAL OF RADIATION BIOLOGY AND RELATED STUDIES IN PHYSICS, CHEMISTRY, AND MEDICINE 1972; 21:159-66. [PMID: 4552387 DOI: 10.1080/09553007214550191] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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17
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Funk F, Sinsheimer RL. Process of infection with bacteriophage phiX174. 33. Templates for the synthesis of single-stranded deoxyribonucleic acid. J Virol 1970; 5:282-8. [PMID: 5438107 PMCID: PMC376002 DOI: 10.1128/jvi.5.3.282-288.1970] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The origin of the templates for the synthesis of phiX174 progeny single-stranded deoxyribonucleic acid was studied by means of the mutagenic activity associated with the decay of incorporated (3)H-labeled 5-cytosine. The results indicate that the single-strand synthesis occurs in an asymmetric semiconservative manner using as template the complementary strands of the pool of replicative from molecules accumulated during the eclipse period. These complementary strands are repeatedly used as templates, and there is no detectable preferential use of complementary strand templates made early in the eclipse versus those made late.
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Abstract
Decay of cytosine-5-(3)H incorporated into bacteriophage S13 DNA causes a molectular rearrangement of the cytosine molecutle undergoing the decay. The molecular rearrangement produces a cytosine to thyimine coding change with at efficiency approaching one. Decay of either thymidine-(methyl)-(3)H or cytosine-6-(3)H is less than 1 percent as effective in calusing either cytosine to thymine or thymine to cytosine transitions.
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Corran J. Analysis of an apparent case of "gene-controlled mutational stability": the auxotrophic preemption of a specific growth requirement. Mutat Res 1969; 7:287-95. [PMID: 4979961 DOI: 10.1016/0027-5107(69)90100-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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21
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Donkersloot JA, Mateles RI. Enrichment of auxotrophic mutants of Aspergillus flavus by tritium suicide. J Bacteriol 1968; 96:1551-5. [PMID: 5726297 PMCID: PMC315209 DOI: 10.1128/jb.96.5.1551-1555.1968] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
A method based on tritium suicide was developed to enrich auxotrophic mutants of Aspergillus flavus. N-methyl-N'-nitro-N-nitrosoguanidine (NG) was chosen as a mutagen, since a wide variety of mutations were induced by the action of 0.1% NG on A. flavus conidia suspended in phosphate buffer (pH 7.0). The decimal reduction time under these conditions was about 30 min, and the surviving population contained 4 to 6% auxotrophs after 1 hr of mutagenesis. This proportion was then increased by tritium suicide of wild-type cells. At a concentration of 1.3 mum, (3)H-leucine was incorporated better than (3)H-proline or (3)H-thymidine into the germinating conidia. With about 20 hr of incubation and a short treatment in a high-speed mixer to disentangle mycelia and conidia, a 5- to 20-fold decrease in the number of survivors resulted from the incorporated (3)H-leucine (5 c/mmole) after 1 week of storage at 5 C. At a 10-fold lower concentration, the uptake of radioactivity and the subsequent suicide rate were much lower. With (3)H-leucine, the proportion of auxotrophs in the surviving population rose from 5 to about 20% during 2 weeks of storage at 5 C. Mutants requiring various intermediates for protein or nucleic acid synthesis or requiring vitamins were isolated. Finally, it was noted that A. flavus shows a much higher resistance to tritium suicide than does Escherichia coli.
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Abstract
Coliphage T4 was used as a model system to study the mechanism of biological inactivation produced by tritium decay. Experimentally, tritiated precursors were incorporated into phage DNA (thymidine-(3)H) or into phage protein ((3)H-amino acids). The ratio of killing efficiencies for decays originating in phage DNA to those originating in phage protein was 2.6. Inactivation by decays from labeled amino acids was assumed to occur exclusively from beta-particle irradiation of phage DNA. If decays originating in DNA are due solely to irradiation of DNA, then the killing efficiencies reflect the energy transfer paths in phage DNA for decays originating in phage DNA and in the protein coat. The energy transfer paths were determined for the two cases with the help of a computer and found to be very nearly equal to the experimentally determined ratio (2.6). The killing efficiencies for decays originating in phage DNA were 0.12 and for decays originating in protein 0.046.
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Bockrath R, Person S, Funk F. Calculated energy deposits from the decay of tritium and other radioisotopes incorporated into bacteria. Biophys J 1968; 8:1027-36. [PMID: 5678319 PMCID: PMC1367391 DOI: 10.1016/s0006-3495(68)86536-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Transmutation of the radioisotope tritium occurs with the production of a low energy electron, having a range in biological material similar to the dimensions of a bacterium. A computer program was written to determine the radiation dose distributions which may be expected within a bacterium as a result of tritium decay, when the isotope has been incorporated into specific regions of the bacterium. A nonspherical model bacterium was used, represented by a cylinder with hemispherical ends. The energy distributions resulting from a wide variety of simulated labeled regions were determined; the results suggested that the nuclear region of a bacterium receives on the average significantly different per decay doses, if the labeled regions were those conceivably produced by the incorporation of thymidine-(3)H, uracil-(3)H, or (3)H-amino acids. Energy distributions in the model bacterium were also calculated for the decay of incorporated (14)carbon, (35)sulfur, and (32)phosphorous.
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Benson B, Snipes W. Free Radicals Formed in Cytosine‐5‐3H by Decay of the Constituent Tritium Atom. J Chem Phys 1968. [DOI: 10.1063/1.1670249] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Bockrath RC, Osborn M, Person S. Nonsense suppression in a multiauxotrophic derivative of Escherichia coli 15T-: identification and consequences of an amber triplet in the deoxyribomutase gene. J Bacteriol 1968; 96:146-53. [PMID: 4874302 PMCID: PMC252265 DOI: 10.1128/jb.96.1.146-153.1968] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Previously, arginine revertants of Escherichia coli WWU, a derivative of E. coli 15T(-), have been subdivided by two independent methods: (i) the streak morphology on nutrient agar, and (ii) the pattern of phage growth using amber and ochre mutants of bacteriophage T4. In the first assay, revertants were subdivided into two classes according to the appearance of streaks after incubation on nutrient agar, a thick, even line of growth defining normal revertants and a thin, irregular line defining aberrant revertants. In the second assay, revertants were classified by the suppressors they contained. The present work demonstrates that revertants containing an amber suppressor show the aberrant morphology and are also able to catabolize thymidine for energy and carbon. This is in contrast to the parent WWU containing no suppressor, which shows a normal morphology and cannot utilize thymidine as an energy source. Revertants containing no suppressor, isolated specifically for their ability to catabolize thymidine, show an aberrant morphology. Together, these results indicate that the aberrant morphology results from suppression of an amber triplet in a gene of the thymidine catabolic pathway. Enzyme assays show the amber triplet to be in the gene specifying deoxyribomutase. It is suggested that the aberrant arginine revertants are analogous to high thymine-requiring mutants and that, in general, high and low thymine-requiring mutants differ from one another in their ability to catabolize deoxyribose-1-phosphate.
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Person S, Osborn M. The conversion of amber suppressors to ochre suppressors. Proc Natl Acad Sci U S A 1968; 60:1030-7. [PMID: 4875805 PMCID: PMC225156 DOI: 10.1073/pnas.60.3.1030] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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Burki HJ, Okada S. A comparison of the killing of cultured mammalian cells induced by decay of incorporated tritiated molecules at--196 degrees C. Biophys J 1968; 8:445-56. [PMID: 5643274 PMCID: PMC1367587 DOI: 10.1016/s0006-3495(68)86499-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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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Bockrath RC. Evidence for two geometrically distinct targets mediating arginine reversion in E. coli. Mutat Res 1967; 4:871-3. [PMID: 4873402 DOI: 10.1016/0027-5107(67)90095-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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29
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Osborn M, Person S. Characterization of revertants of E. coli WU36-10 and WP2 using amber mutants and an ochre mutant of bacteriphage T4. Mutat Res 1967; 4:504-7. [PMID: 4862436 DOI: 10.1016/0027-5107(67)90013-9] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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30
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Osborn M, Person S, Phillips S, Funk F. A determination of mutagen specificity in bacteria using nonsense mutants of bacteriophage T4. J Mol Biol 1967; 26:437-47. [PMID: 6029739 DOI: 10.1016/0022-2836(67)90314-2] [Citation(s) in RCA: 135] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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31
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Person S, Bockrath RC. Evidence for a mutagenic local effect accompanying the decay of incorporated tritium in Escherichia coli. J Mol Biol 1965; 13:600-2. [PMID: 5325730 DOI: 10.1016/s0022-2836(65)80122-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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