Some effects of ultraviolet irradiation on microorganisms

Abstract

w i i w s i t y of Texas, Aiisli/iBased on the assumption that something other than the absorption of energy in the gene and the local change may be involved in tlie production of mutations by irradiation, attempts have been made to determine possible steps between irradiation of living organisms aitd resulting mutation phenomenon. Since some cheiitieal or phJ-sical change must be wespoiisible f o r the modification of the gene causing mutation, the possibility of obtaining gene cliangcs by inodifyiiig the food was explored. Strong evidence of a step bettreen tlie absorption of radiant eiiergv and the mutatiori process would be established if mutation could be produced by nourishiiig the organisms 011 an irradiated substrate (Stone, TTyss and Haas, '47).Demerce ( '45) has sliomrii that the drug-resistant individuals appeariiig in cultures of Staphylococcus CIUWZ(S arise AS a result of mutations. Such inutatioits occur at a low but readily measurable rate, which can be increased by irradiating the organisnis. It was found that ultraviolet irradiation of the medium in which the organisiiis are to be grow11 res;rultecl in manifold increase in the number of niutations. This occiirred with mutatioiia hot11 to penicilliii and t o streptoiiiycin resistance. XATERIBLS ASP METHODSFirst experiments were done with peptone broth but the phenomenon was also observed with a simplcr cheniically Talk dclirered by Dr. Stonr. 133

Experimentally Induced Chromosome Aberrations in Plants

“…The interest in the genetic and cytological effects of cyanide was greatly stimulated by the accumulation of data which indicated that hydrogen peroxide was involved in the production of mutations and chromosome aberrations by radiations (46,43). If hydrogen peroxide is an important cause of mutation and chromosome breakage it would be expected that by inhibiting catalase and peroxidase (the enzymes which are responsible for the destruction of biologically formed peroxide) the natural frequencies of mutation and breakage would be increased.…”

“…Realizing this, Wyss et al (46) tested the influence of subinhibitory concentrations of sodium azide on the rate of mutation to penicillin resistant and streptomycin resistant forms in the bacterium Staphylococcus aureus and observed a marked increase in the frequency of mutation. In Neurospora, Wagner et al (45) observed similar results, using potassium cyanide instead of azide as an inhibitor of the peroxide-destroying enzymes.…”

Genetics of Microorganisms

“…In a prelimi nary report, the effect of ribonucleic acid in increasing the number of spon taneous virus-resistant mutants in nondividing cultures of E. coli is attrib uted to the abolition of phenomic lag (256). Genetic effects of radiation.-Many recent investigations on radiation effects have made use of microorganisms (7,70,120,134,160,191,194,201,232,235,248,259). A useful compilation of older data on dosage-effect relations is now available (265).…”

“…Peroxide pretreatment of media was shown to increase the rate of mutation of Staphy lococcus to penicillin and streptomycin resistance (259,260) and of E. coli to phage resistance (94). Irradiated medium, peroxide, and hydrogen cyanide are all reported to produce biochemically deficient types in Neurospora (248).…”

Spontaneous and Induced Cell Restorations after Treatments with Ionizing and Non-Ionizing Radiations

“…This link between restoring capacity and enzymatic activity of catalase strongly suggests that restoration is due to the decomposition of peroxides which are known as lethal and mutagenic agents on micro-organisms (DICKEY et al 1949), and as active intermediates produced by UV in some organic media (WYSS et al 1950).…”