1887

Abstract

SUMMARY

Lag, exponential and stationary phase cells of lt-2 () grown in nutrient broth or tryptophan-supplemented minimal medium were irradiated with doses of u.v. up to 570 ergs/mm. Casein hydrolysate supplementation of the post-irradiation plating medium causes enhanced survival only for lag and exponential phase broth-grown and exponential phase minimal- grown cells. Caffeine invariably leads to decreased survival levels and abolition of any casein hydrolysate enhancement of survival. Cells of all six growth conditions give induced Trp reversions, often due to suppressor mutations, on plating media containing casein hydrolysate. Only for minimal-grown lag and exponential phase cells do induced Trp appear on media devoid of casein hydrolysate supplementation. In these cases too, caffeine has a definite antimutagenic action. Mutation frequency decline (MFD) experiments revealed that those cells exhibiting a casein hydrolysate enhancement of survival on plates also show a delayed onset of MFD and a fall of survival, after an initial delay, in liquid minimal medium. MFD experiments in liquid do not give a complete quantitative explanation for the Trp revertant yields found on plates. We suggest that intracellular free amino acid pool sizes may be a common factor in the correlations which we have observed.

Loading

Article metrics loading...

/content/journal/micro/10.1099/00221287-68-2-199
1971-10-01
2022-01-24
Loading full text...

Full text loading...

/deliver/fulltext/micro/68/2/mic-68-2-199.html?itemId=/content/journal/micro/10.1099/00221287-68-2-199&mimeType=html&fmt=ahah

References

  1. Bridges B. A., Dennis R. E., Munson R. J. 1967; Differential induction and repair of ultraviolet damage leading to true reversions and external suppressor mutations of an ochre codon in Escherichia coli b/r WP 2. Genetics 57:897–908
    [Google Scholar]
  2. Clarke C. H. 1967; Caffeine- and amino acid-effects upon try+revertant yield in u.v.-irradiated hcr+ and her mutants of Escherichia coli b/r. Molecular and General Genetics 99:97–108
    [Google Scholar]
  3. Clarke C. H. 1969a; Influence of cellular physiology on the realization of mutations - results and prospects. Ciba Foundation Symposium on Mutation as Cellular Process pp. 17–28 Wolsten- holme G. E. W., O’Connor M. Edited by London: Churchill;
    [Google Scholar]
  4. Clarke C. H. 1969b; Chemical mutagenesis in Escherichia coli b/r; the influence of repair systems for u.v, damage. Mutation Research 8:35–41
    [Google Scholar]
  5. Demerec M., Cahn E. 1953; Studies of mutability in nutritionally deficient strains of Escherichia coli. Journal of Bacteriology 65:27–36
    [Google Scholar]
  6. Doudney C. O., Haas F. L. 1958; Modification of ultraviolet-induced mutation frequency and survival in bacteria by post-irradiation treatment. Proceedings of the National Academy of Sciences 44:390–401
    [Google Scholar]
  7. Doudney C. O., Haas F. L. 1959; Mutation induction and macromolecular synthesis in bacteria. Proceedings of the National Academy of Sciences 45:709–722
    [Google Scholar]
  8. Doudney C. O., Young C. S. 1962; Ultraviolet light induced mutation and deoxyribonucleic acid replication in bacteria. Genetics 47:1125–1138
    [Google Scholar]
  9. Hill R. F. 1965; Ultraviolet-induced lethality and reversion to prototrophy in Escherichia coli strains with normal and reduced dark repair ability. Photochemistry and Photobiology 4:563–568
    [Google Scholar]
  10. Hill R. F. 1968; Modification of lethality and mutagenesis by growth inhibition of ultraviolet-irradiated Escherichia coli strain b/r. Journal of General Microbiology 52:261–270
    [Google Scholar]
  11. Witkin E. M. 1956; Time, temperature, and protein synthesis: a study of ultraviolet-induced mutation in bacteria. Cold Spring Harbor Symposia on Quantiative Biology 21:123–140
    [Google Scholar]
  12. Witkin E. M. 1961; Modification of mutagenesis initiated by ultraviolet light through post treatment of bacteria with basic dyes. Journal of Cellular and Comparative Physiology 58: Suppl 135–144
    [Google Scholar]
  13. Witkin E. M. 1963; ‘Dark repair’ of mutations induced in Escherichia coli by ultraviolet light. Repair from Genetic Radiation Damage pp. 151–161 Sobels F. H. Edited by Oxford: Pergamon Press;
    [Google Scholar]
  14. Witkin E. M. 1966a; Mutation and the repair of radiation damage in bacteria. Radiation Research Supplement 6:30–53
    [Google Scholar]
  15. Witkin E. M. 1966b; Radiation-induced mutations and their repair. Science; New York: 1521345–1353
    [Google Scholar]
  16. Witkin E. M. 1969; Ultraviolet-induced mutation and DNA repair. Annual Review of Genetics 3:525–552
    [Google Scholar]
  17. Witkin E. M., Theil E. C. 1960; The effect of post-treatment with chloramphenicol on various ultra violet-induced mutations in Escherichia coli. Proceeding of the National Academy of Sciences 46:226–231
    [Google Scholar]
http://instance.metastore.ingenta.com/content/journal/micro/10.1099/00221287-68-2-199
Loading
/content/journal/micro/10.1099/00221287-68-2-199
Loading

Data & Media loading...

Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error