INTERRELATIONS OF NUCLEIC ACID AND PROTEIN SYNTHESES IN RADIATION INDUCED MUTATION INDUCTION IN BACTERIA

Technical Report · Thu Oct 30 23:00:00 EST 1958

OSTI ID:4330011

Haas, F L; Doudney, C O

During the past decade evidence has accumulated that an appreciable portion of radiation-induced mutations are due to chemical effects of radiation on sensitive metabolites. The shape of induced mutation frequency curves suggests that intracellular radiation-sensitive material is modified by radiation. This material is probably both limited in quantity and destroyed by radiat high doses of radiation then usually decreases at still higher doses. We have found, using microorganisms, that the frequency of mutation per unit dose and maximum mutation frequency induced by ulraviolet (U.V.) may be increased considerably for various mutations. The same holds true when ionizing radiations are used, but increases in mutation frequency are smaller than with U.V. Increase is obtained by preirradiation incubation tion in a minimal medium supplemented with yeast extract, a combination of purines and pyrimidines (adenine, or guanine, uracil, and cytosine) or their ribosides, riboflavin, or p-aminobenzoic acid. By using cultures synchronized in growth and division, the following has been established in refard to the puring-pyrimidine influence on U.V. -induced mutation: maximum frequency increase is attained by irradiating during maximum nucleic acid synthesis; little increase is observed following the first nuclear division; maximum frequency is reduced by cellular division; increased frequuency obtained by purine-pyrimidine incubation bears no relation to cellular nucleic acid content-increase in nucleic acid precursors prior to irradiation is the important factor; increase in mutation frequency by purine-pyrimidine preirradiation incubation is dependent on postirradiation ribonucleic acid and protein syntheses. Postirradiation nitrogen-starvation, or inhibition of RNA-protein synthesis system with chloramphenical or 5mutation frequency. The mutagenic eftect of U.V. is modification of intracelluler nucleic acid precursors. These modified precursors are stabilized by an aminoacid-dependent enzymatic process referred to as mutation stabilization. If stabilization is prevented they are rapidly removed by a second enxymatic process referred to as mutation frequency decline. Mutation is brought about by incorporation of the modified nucleic acid precursor(s) dfuring macromolecular synthesis of RNA and protein, or mutation fixation. The nature of the link (if any) between modification of RNA and modification of the configuration of cellular DNA (the gene), though suggested by these results, is unknown. RNA and protein formation are involved in DNA synthesis, and perhaps changes in RNA biological specificity lead to corresponding changes in the biological specificity of genic DNA. (auth)

• Research Organization: Texas. Univ., Houston. M.D. Anderson Hospital and Tumor Inst.
• NSA Number: NSA-12-014496
• OSTI ID: 4330011
• Report Number(s): A/CONF.15/P/896
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

AMINO ACIDS-- ANTIBIOTICS-- BIOCHEMISTRY-- BIOLOGY-- CHEMICALS-- CHLORAMPHENICOL-- CYTOLOGY-- DNA-- ENZYMES-- GENETICS-- IRRADIATION-- MOLECULES-- MUTATIONS-- NITROGEN-- NUCLEIC ACIDS-- PROTEINS-- QUANTITY RATIO-- RIBONUCLEIC ACID-- STABILITY-- ULTRAVIOLET RADIATION-- VARIATIONS
BACTERIA-- BIOCHEMISTRY-- CONFERENCE-- CYTOLOGY-- DIAGRAMS-- ENVIRONMENT-- HETEROCYCLICS-- IONIZATION-- MITOSIS-- MUTATIONS-- NUCLEIC ACIDS-- ORGANIC NITROGEN COMPOUNDS-- PHYSIOLOGY-- PROTEINS-- PURINES-- PYRIMIDINES-- QUANTITY RATIO-- RADIATION DOSES-- RADIATION EFFECTS-- RADIOSENSITIVITY-- RIBONUCLEIC ACID-- RIBOSIDES-- ULTRAVIOLET RADIATION-- VARIATIONS-- VITAMIN
BIOLOGY AND MEDICINE