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Journal ArticleDOI

Growth and reactivation of single stranded DNA phage phiX174 in E. coli undergoing "thymineless death".

16 Mar 1977-Molecular Genetics and Genomics (Springer-Verlag)-Vol. 151, Iss: 3, pp 313-318
TL;DR: To test if the thymine necessary for phage growth under “thymineless” conditions was supplied by host DNA degradation products, the transfer of 32P label from the host DNA to mature progeny phages was measured by means of sucrose density gradient analysis.
Abstract: The thymine requirement of the E. coli strain HF 4704 (uvr A-, rec A+) is thermosensitive i.e. these cells require for their growth 2 microng thymine per ml at 37 degrees C but not at 30 degrees C. Such cells when starved for thymine for 3 h at 37 degrees C are capable of sustaining growth of single stranded DNA phage phiX174 without any diminution of burst size under nonpermissive conditions. Thymine starved HF 4704 cells also reactivate UV-irradiated phiX174 by about 3fold. To test if the thymine necessary for phage growth under "thymineless" conditions was supplied by host DNA degradation products, the transfer of 32P label from the host DNA to mature progeny phages was measured by means of sucrose density gradient analysis. It was found that only about 0.7% of 32P of the host DNA was transferred to the progeny phages growing in normal cells whereas the corresponding value was 7.8% in the case of thymine starved cells.
Citations
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Journal ArticleDOI
TL;DR: It is proposed that instability of single-strand gaps underlies the pathology of thymine starvation, with the nature of the resistance phase and of the transition to the RED phase holding key to TLD pathology.

8 citations

Book ChapterDOI
01 Jan 1981
TL;DR: In this paper, it was shown that the spectrum of light now emitted by the sun closely approximates the continuous theoretical spectral distribution (as derived by Planck) calculated for a perfect absorber in thermal equilibrium at 5800°K (see Eisberg, 1961).
Abstract: Ultraviolet (UV) light has been a component of the radiation emitted by the sun toward our planet for approximately 4.6 × 109 years, the age of our solar system (see, for example, Krogdahl, 1962). The spectrum of light now emitted by the sun closely approximates the continuous theoretical spectral distribution (as derived by Planck) calculated for a perfect absorber in thermal equilibrium at 5800°K (see Eisberg, 1961). The actual emission in the UV region is reduced with respect to the expected theoretical value because the solar photosphere, having a finite thickness and being partially composed of good UV absorbers, shows strong UV absorption (Stair, 1969). Furthermore, although the outer edge of the photosphere does contribute somewhat to the UV spectrum, this is precisely the region of minimum solar temperature (about 4300°K). And, because of the strong dependence on temperature of the energy output, the photospheric emission in the UV region is low. Out-ward from the solar photosphere is the extremely hot chromosphere, followed by the solar corona of average temperature 1–2 × 1060K.

4 citations

Journal ArticleDOI
TL;DR: The maximal error-prone repair capacity, which was induced in the cell during the 30 min nalidixic acid treatment, rapidly died out during subsequent cell growth in absence of nalidxic acid.
Abstract: Inducible error-prone DNA repair activity was detected by infecting nalidixic acid-pretreated E. coli cells with UV-irradiated phage φX174. Induction and decay kinetics of reactivation very much resembled that of mutagenesis of the UV-damaged phage. Repair as well as mutagenic activity increased for about 30 min. The maximal error-prone repair capacity, which was induced in the cell during the 30 min nalidixic acid treatment, rapidly died out during subsequent cell growth in absence of nalidixic acid. Induction of this repair mode was not observed in a recA− mutant. In the presence of nalidixic acid plus rifampicin both repair and mutagenic effects were abolished.

2 citations

References
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Journal ArticleDOI
01 Dec 1975
TL;DR: The Single-Stranded DNA Phages (SDSDP) as discussed by the authors is a set of single-stranded DNA phages that can be found in the DNA sequences of the human genome.
Abstract: (1975). The Single-Stranded DNA Phages. CRC Critical Reviews in Microbiology: Vol. 4, No. 2, pp. 161-223.

225 citations


"Growth and reactivation of single s..." refers background in this paper

  • ...This minute phage harbours only 8 genes and these are now fairly well characterized to render such a possibility very unlikely (Denhardt, 1975)....

    [...]

Book ChapterDOI
TL;DR: The analysis of some of the evident integrated aspects of viral replication, which may well depend upon a complex structural basis for specific interactions, may, therefore, require extensive in vivo studies for some time to come.
Abstract: Publisher Summary This chapter focuses on bacteriophage φ X174 and related viruses. As a consequence of an extended program of research in several laboratories, many of the reactions involved in the replication of the bacteriophage φ X174 are known. The replication, even of this simple virus, is clearly an intricate and integrated process, precisely adapted to the circumstances in the host cell. The replication of the viral nucleic acid is intimately related to the repair and replication processes of the host DNA; the analysis of the replication of the viral DNA (and its regulation) may serve as a model system to provide new insights into the analogous processes for the host DNA. It is important to know that many of the stages of viral DNA replication and viral assembly will be performed in vitro in the near future. However, the analysis of some of the evident integrated aspects of viral replication, which may well depend upon a complex structural basis for specific interactions, may, therefore, require extensive in vivo studies for some time to come.

155 citations

Journal ArticleDOI
20 Apr 1963-Nature
TL;DR: Evidence is provided that messenger-RNA synthesis in particular is necessary for the killing event in thymine-deficient cultures, and that the inhibitory effect of 5-methyl tryptophan could be partially reversed (with respect to RNA synthesis and thymineless killing) by chloramphenicol.
Abstract: THE phenomenon of thymineless death in bacteria1 is of particular interest because of its apparent relationship to DNA replication, as shown by Maaloe and Hanawalt2. Only those bacterial cells which are synthesizing DNA at the time thymine is removed from the culture medium appear to be susceptible to thymineless killing under conditions of protein synthesis inhibition3. The 97 per cent susceptible fraction from an exponentially growing culture of strain TAU (E. coli 15T–A–U–, requiring thymine, arginine and uracil) succumbs to the lethality of thymine deficiency at about the same rate whether arginine and uracil are present or not2. Thus, little correlation exists between thymineless killing and cytoplasmic synthesis. Using E. coli B3 Gallant and Suskind4 also reported thymineless death under conditions of protein synthesis inhibition, but they found further that phosphate starvation prevented killing. They implicated RNA synthesis on the basis of this result and the finding that the inhibitory effect of 5-methyl tryptophan could be partially reversed (with respect to RNA synthesis and thymineless killing) by chloramphenicol. The investigations to be reported here provide evidence that messenger-RNA synthesis in particular is necessary for the killing event in thymine-deficient cultures.

107 citations


"Growth and reactivation of single s..." refers background in this paper

  • ...Although the exact causes remain to be fully identified, it has been shown to be associated with production of damaged DNA (Freifelder, 1969), synthesis of faulty mRNA (Hanawalt, 1963) and appearance of new protein (Dankberg and Cummings, 1973)....

    [...]

Journal ArticleDOI
TL;DR: A thymine-requiring strain of Escherichia coli containing a sex factor has been starved of thymine and examined by zone centrifugation in alkaline sucrose gradients for survival of circular sex factor DNA molecules, finding that the rates of loss are proportional to DNA molecular weight.

88 citations


"Growth and reactivation of single s..." refers background in this paper

  • ...Although the exact causes remain to be fully identified, it has been shown to be associated with production of damaged DNA (Freifelder, 1969), synthesis of faulty mRNA (Hanawalt, 1963) and appearance of new protein (Dankberg and Cummings, 1973)....

    [...]