SINGLE‐STRAND BREAKS INDUCED IN <i>BACILLUS SUBTILIS</i> DNA BY ULTRAVIOLET LIGHT: ACTION SPECTRUM and PROPERTIES

Peak, Meyrick J.; Peak, Jennifer G.

doi:10.1111/j.1751-1097.1982.tb02628.x

Cited by 109 publications

(50 citation statements)

References 36 publications

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“…The sedimentation profiles for P. furiosus DNA were similar to those described previously for E. coli and Bacillus subtilis (11,16), having a single DNA peak as illustrated in Fig. 1 for control (untreated) P. furiosus DNA (the low point of fraction 17 is an anomaly of this particular gradient).…”

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confidence: 53%

“…At the end of the treatment time, the cell suspension was cooled in ice and transferred to centrifuge tubes for lysis. The procedures for number-average DNA molecular mass (M n ) determination from sedimentation coefficients of DNA and calculation of the numbers of backbone breaks were exactly as described previously (11,16). For E. coli, treated cells were lysed on top of 5 to 20% alkaline sucrose gradients, and the DNA was centrifuged in an SW55Ti swing-out rotor as described previously (11).…”

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confidence: 99%

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Extreme resistance to thermally induced DNA backbone breaks in the hyperthermophilic archaeon Pyrococcus furiosus

1995

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Pyrococcus furiosus is a hyperthermophilic archaeon that grows optimally at 100؇C. It is not conceivable that these organisms could survive with genomic DNA that was subject to thermal destruction, yet the mechanisms protecting the genomes of this and other hyperthermophiles against such destruction are obscure. We have determined the effect of elevated temperatures up to 110؇C on the molecular weight of DNA in intact P. furiosus cells, compared with the effect of elevated temperatures on DNA in the mesothermophilic bacterium Escherichia coli. At 100؇C, DNA in P. furiosus cells is about 20 times more resistant to thermal breakage than that in E. coli cells, and six times fewer breaks were found in P. furiosus DNA after exposure to 110؇C for 30 min than in E. coli DNA at 95؇C. Our hypothesis for this remarkable stability of DNA in a hyperthermophile is that this hyperthermophile possesses DNA-binding proteins that protect against hydrolytic damage, as well as other endogenous protective mechanisms and DNA repair enzyme systems.The chemical effects of elevated temperatures on DNA are believed to be hydrolytic: (i) phosphodiester bond scission (backbone breakage); (ii) cleavage of N-glycosyl bonds (rendered labile by the lack of the sugar 2Ј-OH bond), resulting in base elimination, producing an apurinic or apyrimidinic site that weakens the DNA chain, which also then enhances cleavage by ␤-elimination; and (iii) hydrolytic base deamination, particularly at the 4 position of cytosine (5). In a series of papers, Lindahl and coworkers have measured the rates of these hydrolytic changes in DNA caused by high temperature (5-9). It was calculated by extrapolation that DNA at 100ЊC would experience approximately 3,000 times more hydrolytic events than DNA at 37ЊC (5). For backbone breaks in depurinated DNA, no measurements above 70ЊC were described (9).The problem of topological DNA stability in thermophiles and hyperthermophiles was the subject of a recent chapter (4); however, DNA backbone stability in hyperthermophiles has not previously been addressed. The purpose of our work was to determine the effects of temperatures higher than 90ЊC on DNA in vivo by comparing the integrity of DNA in a mesophilic cell to that in a hyperthermophile. Here we describe our comparison of DNA backbone breakage resulting from phosphodiester bond cleavage (including the production of AP sites leading to backbone cleavage by ␤-elimination).Alkaline sedimentation of P. furiosus DNA. P. furiosus (DSM 3638) was grown to about 4 ϫ 10 8 cells per ml in sealed culture tubes in an artificial seawater medium supplemented with yeast extract (1%) and tryptone (0.5%) modified from that described by Brown and Kelly (2). Yeast extract and tryptone were from Difco Laboratories (Detroit, Mich.), and maltose, deoxyadenosine, thymidine, proteinase K, and Sarkosyl were from Sigma Chemical Co. (St. Louis, Mo.). Radiolabelled thymidine was obtained from ICN Radiochemicals (Irvine, Calif.). Tungsten (3.75 M NaWO 4 ⅐ 2H 2 O) and maltose (0.5%) were used in plac...

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confidence: 53%

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confidence: 99%

Extreme resistance to thermally induced DNA backbone breaks in the hyperthermophilic archaeon Pyrococcus furiosus

1995

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“…Wave-lengths above 347 nm (UV-A: 315 ± 400 nm) do not cause DNA damage by direct absorption of photons (Peak et al, 1987), so that DNA damage is supposedly induced by indirect mechanisms, i.e. reactive oxygen species causing single and double strand breaks (Peak and Peak, 1982).…”

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confidence: 99%

Tumorigenic conversion of immortal human skin keratinocytes (HaCaT) by elevated temperature

et al. 1999

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UV-radiation is a major risk factor for non-melanoma skin cancer causing speci®c mutations in the p53 tumor suppressor gene and other genetic aberrations. We here propose that elevated temperature, as found in sunburn areas, may contribute to skin carcinogenesis as well. Continuous exposure of immortal human HaCaT skin keratinocytes (possessing UV-type p53 mutations) to 408C reproducibly resulted in tumorigenic conversion and tumorigenicity was stably maintained after recultivation of the tumors. Growth at 408C was correlated with the appearance of PARP, an enzyme activated by DNA strand breaks and the level corresponded to that seen after 5 Gy g-radiation. Concomitantly, comparative genomic hybridization (CGH) analyis demonstrated that chromosomal gains and losses were present in cells maintained at 408C while largely absent at 378C. Besides individual chromosomal aberrations, all tumor-derived cells showed gain of chromosomal material on 11q with the smallest common region being 11q13.2 to q14.1. Cyclin D1, a candidate gene of that region was overexpressed in all tumor-derived cells but cyclinD1/ cdk4/cdk6 kinase activity was not increased. Thus, these data demonstrate that long-term thermal stress is a potential carcinogenic factor in this relevant skin cancer model, mediating its e ect through induction of genetic instability which results in selection of tumorigenic cells characterized by gain of 11q.

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“…2 The highenergetic UV-B radiation constitute <1% of the total solar irradiance. It affects normal states of life either through direct effects on cellular nucleic acids (denaturation of DNA and RNA) or indirectly by the production of reactive oxygen species (ROS) 3,4 in various living systems including phytoplankton, 5 bacteria 6 and cyanobacteria. 7 In contrast, UV-A (315-400 nm) radiation is not absorbed directly by the native DNA, but still induce DNA damage either by producing a secondary photoreaction of existing DNA photoproducts or via indirect photosensitizing reactions.…”

Section: Introductionmentioning

confidence: 99%

Screening and partial purification of photoprotective pigment scytonemin from cyanobacterial crusts dwelling on the historical monuments in and around Varanasi, India

Pathak

Sonker

Rashmi

et al. 2017

Microbiol Res (Pavia)

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In the present investigation, biological crusts from the surface of eight historical monuments of Varanasi, India, were examined for the presence of scytonemin (a cyanobacterial photoprotective pigment) containing cyanobacterial species. Lyngbya sp. and Scytonema sp. were the dominant cyanobacteria present in all crust samples. The absorption spectroscopic data of chlorophyll, carotenoids and scytonemin showed that scytonemin was more abundant than the carotene and chlorophyll in all the crusts. Identification of these compounds was done using UV-Vis spectroscopy and High Performance Liquid Chromatography (HPLC) analysis. HPLC analysis revealed the presence of scytonemin in seven out of eight samples and peaks of scytonemin with retention time ranging from 1.4-1.9 min with corresponding absorbance maxima at 386, 300 and 252±2 nm. As per our knowledge this is the first report of its kind from monuments of Varanasi. From this study, it can be concluded that synthesis of photoprotective compounds like scytonemin and its derivatives counteract the damaging effects of solar radiation which enable cyanobacteria to colonize and inhabit almost all kinds of habitats, including extreme lithic habitats, such as rocks and walls of monuments which face prolonged high intensity solar radiation.

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SINGLE‐STRAND BREAKS INDUCED IN BACILLUS SUBTILIS DNA BY ULTRAVIOLET LIGHT: ACTION SPECTRUM and PROPERTIES

Cited by 109 publications

References 36 publications

Extreme resistance to thermally induced DNA backbone breaks in the hyperthermophilic archaeon Pyrococcus furiosus

Extreme resistance to thermally induced DNA backbone breaks in the hyperthermophilic archaeon Pyrococcus furiosus

Tumorigenic conversion of immortal human skin keratinocytes (HaCaT) by elevated temperature

Screening and partial purification of photoprotective pigment scytonemin from cyanobacterial crusts dwelling on the historical monuments in and around Varanasi, India

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