A Study of the Bactericidal Action of Ultra Violet Light

Gates, Frederick L.

doi:10.1085/jgp.13.2.249

Cited by 33 publications

(15 citation statements)

References 2 publications

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“…When Experiment 91 is used, at 8 ° , in which the temperature could not be observed to change over the entire course of the exposures, a lower value of 1.058 is obtained for the range 8-24 ° . This is in good agreement with the low value 1.06 obtained for lethal action on bacteria (8).…”

Section: Temperature In Relation To the Lethal Effectsupporting

confidence: 92%

Results of Irradiating Saccharomyces With Monochromatic Ultra-Violet Light

Oster

1934

Journal of General Physiology

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It has been shown previously (1, 2) that the action of monochromatic ultra-violet radiation on the yeast Saccharomyces cerevisiae is not an all or none effect, but is a graded result varying from induction of simple inability to form normal sized colonies to "death" of the ~ell, through different degrees of damage, and involving in some stages the formation of giant cells. The mean "survival" curves for irradiated 24 hour cultures (2) resemble the curve for a first order process, but on this assumption divergences indicate the presence of modifying factors.The present paper deals with several factors which may modify the absorption of energy and the cell processes resulting from irradiation of yeast with ultra-violet light. Age of the CellsSimilar to the effects observed with other organisms (3, 4), the age of the yeast culture has a marked influence on the relative resistance of the cells to lethal irradiation, as measured by the energy required to suppress budding (2). This is illustrated by a comparison of the results obtained on irradiating two cultures of widely different periods of incubation, (A) a 24 hour culture and (B) a 15 day culture of yeast, both incubated at 25°C. and irradiated in a large quartz monochromator at the wave-length 2535 A. u. as previously described (2) after inoculation on malt agar contained in small Petri plates. As shown in Fig. 1, from 20 to 50 per cent more incident energy to produce a given effect is required for the 15 day culture than for the 24 hour cultures. This is best explained on the basis that the greater 243

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Section: Temperature In Relation To the Lethal Effectsupporting

confidence: 92%

Results of Irradiating Saccharomyces With Monochromatic Ultra-Violet Light

Oster

1934

Journal of General Physiology

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“…In addition stationary-phase populations are often more resistant than logarithmicphase populations to U.V. radiation (Durham & Wyss, 1956; Gates, 1929; Woodside, Goucher & Kocholaty, 1960) and to ionizing radiation (Stapleton, 1955). However, neither the changes in metabolic state nor the mechanisms by which such changes alter radiation-killing are understood.…”

Section: Introductionmentioning

confidence: 99%

Evidence that Initial Ultraviolet Lethal Damage in Escherichia coli Strain 15 T-A-U- is Independent of Growth Phase

Ginsberg

Jagger

1965

Journal of General Microbiology

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SUMMARYA study was made of the kinetics of killing by ultraviolet (u.v.) radiation (2537 a) and subsequent photo-reactivation (with black light) of Escherichia C O I ?~ strain 15 T-A-U-(requires thymine, arginine, uracil) by using (a) logarithmic-phase cultures, ( b ) early-stationary-phase cultures, ( c ) logarithmic-phase cultures after 90 min. of incubation in the absence of arginine and uracil (-AU cultures). The stationary and -AU cultures showed the same enhanced resistance to U.V. killing. In all three cultures (1) the photo-reactivable sectors were the same, (2) the rate of photoreactivation was the same function of U.V. dose, (3) the amount of light required for maximum photo-reactivation was a linear function of the U.V. dose. We conclude that the initial lethal lesions produced by a given U.V. dose were qualitatively and quantitatively the same in all three cultures, despite differences in U.V. survival. This implies that the stationary-phase cultures and the -AU cultures were more radiation resistant solely because they were better able to cope with the initial lethal damage. The survival curves can be satisfactorily described mathematically in terms of this model.

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confidence: 46%

Evidence for Thermal Reactions Following Exposure of Didinium to Intermittent Ultraviolet Radiations

Giese

Shepard

Bennett

et al. 1956

The Journal of General Physiology

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Many previous workers have found low intensity ultraviolet (UV) radiation less effective than high intensity UV in producing injury to various living organisms (Christensen, 1953;Coblentz and Fulton, 1924;Dreyer, 1903;Gates, 1929; Swann and del Rosario, 1932;Weinstein, 1930;Wyckoff, 1932). Experiments performed here on the protozoan Didinium nasutum, indicated an opposite, greater effect of low intensity UV. It appeared likely that a dark reaction succeeds the absorption of UV, so that quanta are supplied at high intensity more rapidly than they can be utilized; i.e., saturation occurs. To investigate this possibility the UV was flashed and the dark period between flashes varied, with the expectation of increased injury with longer dark periods. Since a dark reaction is thermochemical, it should proceed more rapidly at high than at low temperature, and injury should therefore increase with temperature. Experiments were accordingly carried out at various temperatures. The expectations have been confirmed in the present study. The effects of variable light period and flash rate, and the comparison of flashed high intensity with continuous low intensity irradiation have also been explored. Materials and MethodsCultures of Didinium nasutum were grown in 4 ram. bore isolation tubes on concentrated suspensions of Paramecium caudatum in the manner previously described (Brandt el a/., 1955). Didinia selected at random for a sample were irradiated in a quartz cell, put into isolation tubes with food, one animal per tube, and the number ha each tube was recorded three times daily, as a rule, until the fourth division was reached ha all tubes. This stage was usually reached earlier in some tubes than ha others, and the tubes were discarded as they attained it, since higher counts were difficult to make, and were likely to be biased because of rapid depletion of the food supply.

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A Study of the Bactericidal Action of Ultra Violet Light

Cited by 33 publications

References 2 publications

Results of Irradiating Saccharomyces With Monochromatic Ultra-Violet Light

Results of Irradiating Saccharomyces With Monochromatic Ultra-Violet Light

Evidence that Initial Ultraviolet Lethal Damage in Escherichia coli Strain 15 T-A-U- is Independent of Growth Phase

Evidence for Thermal Reactions Following Exposure of Didinium to Intermittent Ultraviolet Radiations

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