Physiological Responses of Escherichia coli to Far-Ultraviolet Radiation

Swenson, P. A.

doi:10.1007/978-1-4684-2574-1_7

Cited by 61 publications

(24 citation statements)

References 348 publications

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“…The characteristics of DNA synthesis in B. fragilis cells irradiated with far-UV light under anaerobic conditions differ from those reported for E. coli, where DNA synthesis is stopped completely and immediately by UV irradiation (Kelner, 1953;Swenson, 1976;Hall & Mount, 1981). This inhibition of DNA synthesis in E. coli cells is dependent on a functional recA gene product (Trgovcevic et al, 1980).…”

Section: Discussionmentioning

confidence: 57%

“…Although some DNA degradation does occur in wild-type E. coli cells after UV irradiation it is limited (Swenson, 1976). Extensive 'reckless' DNA degradation occurs in recA mutants following UV irradiation (Clark, 1973).…”

Section: Discussionmentioning

confidence: 99%

“…DNA synthesis in Escherichiu coli and a number of other aerobic bacteria is inhibited by far-UV radiation (254 nm) (Kelner, 1953;Swenson & Setlow, 1966;Swenson, 1976;Trgovcevic et al, 1980). Inhibition of DNA synthesis occurs almost immediately.…”

Section: Introductionmentioning

confidence: 99%

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Effect of UV Irradiation on Macromolecular Synthesis and Colony Formation in Bacteroides fragilis

1984

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Irradiation of Bacteroidesfiagilis cells with far-UV light resulted in the immediate, rapid and extensive degradation of DNA which continued for 40 to 60 min after irradiation. During the degradation phase, DNA synthesis was decreased but was never totally inhibited. DNA degradation after irradiation was inhibited by chloramphenicol and caffeine. DN'4 synthesis in irradiated cells was reduced by chloramphenicol but resumed after 100 min at the same exponential rate as in irradiated cells without chloramphenicol. Irradiated cells continued to synthesize DNA for 40 min in the presence of caffeine but after this time DNA synthesis was completely inhibited and never recovered. RNA and protein synthesis were decreased by UV irradiation and the degree of inhibition was proportional to the UV dose. Colony formation was not affected immediately by UV irradiation and continued for a dose-dependent period before inhibition. There was an inverse relationship between UV dose and inhibition of colony formation which occurred sooner in cells irradiated with lower doses of UV light. The characteristics of DNA synthesis in B. jiagilis cells after UV irradiation differ from those in wild-type Escherichia coli cells, where DNA synthesis is stopped immediately by UV irradiation, but resemble those in E. colirecA mutant cells where extensive degradation occurs following UV irradiation.

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Section: Discussionmentioning

confidence: 57%

Section: Discussionmentioning

confidence: 99%

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Effect of UV Irradiation on Macromolecular Synthesis and Colony Formation in Bacteroides fragilis

1984

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“…The number of "targets" estimated by extrapolating the exponential phase back to the log NIN, axis is six. In the exponential phase the dose, Do, that reduces the survivingfraction to l/e of its original value is taken as a measure of the toxicity of the treatment (Swenson 1976 obtained with N,. Survival was consistently observed to be enhanced in air as opposed to anaerobic conditions.…”

Section: Respiration Experimentsmentioning

confidence: 99%

Photosensitization of Escherichia coli and Saccharomyces cerevisiae by phenylheptatriyne from Bidens pilosa

Arnason¹,

Ck²,

Downum³

et al. 1980

Can. J. Microbiol.

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Escherichia coli and Saccharomyces cereuisiae by phenylheptatriyne from Bidenspilosa. Can. J. Microbiol. 26: 698-705.The photosensitizing action of 7-phenylhepta-2,4,6triyne (PHT), a polyacetylenic compound isolated from Bidens pilosa L. (Asteraceae), has been studied using Escherichia coli and Saccharomycrs cereuisiae as the test organisms. The survival curves for E. colitreated with PHTand ultraviolet (UV) radiation wereobtained and have been interpreted quantitatively on the basis ofa target theory model. The number of "targets" in the cell that must be destroyed before cell death occurs was estimated at six, whereas the dose, Do, that reduced the surviving fraction of the population to I/e of its value was estimated to be 280 J/m2. Survival was enhanced in aerobic conditions as compared with anaerobic conditions, which is strong evidence that PHT does not behave as a photodynamic sensitizer in vivo. This view was confirmed by work with azide (a quencher of singlet oxygen), D 2 0 (which increases the lifetime of singlet oxygen), and superoxide dismutase (which scavenges superoxide radicals). None of these treatments modified the survival curves significantly, indicating that activated species of 0, are probably not involved in photosensitizations with PHT in vivo.Cell respiration was found to be rapidly inhibited by mild treatments of PHT and UV radiation, suggesting that nuclear metabolism is not the primary target of photosensitization as is the case with another group of photosensitizers, the furanocoumarins. The available evidence indicates that PHT is a representative of a new class of phototoxic compounds. A mechanism of action involving production of free radicals is proposed. ARNASON, THOR, CHI-KIT WAT. KELSEY DOWNUM, ETSUO YAMAMOTO, ELIZABETH GRAHAM et G. H. NEIL TOWERS. 1980. Photosensitization of Eschrrichia coli and Saccharotnyces crreuisiae by phenylheptatriyne from Bidenspilosa. Can. J. Microbiol. 26: 698-705. Nous avons etudie, en utilisant Escherichia coli et Saccharornyces cereuisiae comme organismes tests, l'effet photosensibilisateur du 7-phknylhepta-2,4,6triyne (PHT), un compose polyacktylenique isole de Bidens pilosa L. (Asteraceae). Nous avons obtenu des courbes de survie pour des cellules d'E.coli traitees au PHTet aux rayons ultraviolets(UV); ces courbesont ete interpretees quantitativement partir d'un modele reposant sur la theorie des cibles. Le nombre de "cibles" qui doivent itre detrouites avant que la mort cellulaire ne survienne a etC estime a six; quant a la dose Do qui reduit a I/e le fraction des survivants, elle a ete estimee a 280 J/m2. La survie etait meilleure sous des conditions aerobies qu'anairobies: ceci renforce I'evidence que le PHT ne se comporte pas comme un sensibilisateur photodynamique in vivo. Ce point a ete confirme en verifiant les effets de I'azoture (extincteur de I'oxygene singulet), du D,O (qui prolonge la durke de vie de I'oxygene singulet) et de la superoxyde dismutase (qui capte les radicaux superoxyde). Aucun de ces traitements n'a modifii de f a~o n s...

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“…It has been suggested that irradiation may cause derepression of operons leading to a general disturbance of cellular metabolism [12,19] and ultimately to cell death. This study is aimed at the investigation of the two inducible enzymes arginase and ornithintranscarbamylase (OTCase) in UV-irradiated yeast cells of different sensitivity.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of inducible enzymes in irradiated yeast: UV effects on regulation and activity per cell

Gocke

Kiefer

1978

Radiat Environ Biophys

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The synthesis of two inducible enzymes in UV irradiated cells was determined during an 8 h postirradiation incubatin. In contrast to the reduction of synthesis shortly after irradiation the effect after a longer period of incubation depends on the radiation sensitivity of the strain. Since exposure inhibits division leading to different cell number in controls and irradiated samples the data are also analysed on a per cell basis. ta considerable increase of the activity per cell was observed. A maximum is reached at the end of the division delay.

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Physiological Responses of Escherichia coli to Far-Ultraviolet Radiation

Cited by 61 publications

References 348 publications

Effect of UV Irradiation on Macromolecular Synthesis and Colony Formation in Bacteroides fragilis

Effect of UV Irradiation on Macromolecular Synthesis and Colony Formation in Bacteroides fragilis

Photosensitization of Escherichia coli and Saccharomyces cerevisiae by phenylheptatriyne from Bidens pilosa

Synthesis of inducible enzymes in irradiated yeast: UV effects on regulation and activity per cell

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