scholarly journals Artificial and Solar UV Radiation Induces Strand Breaks and Cyclobutane Pyrimidine Dimers in Bacillus subtilis Spore DNA

2000 ◽  
Vol 66 (1) ◽  
pp. 199-205 ◽  
Author(s):  
Tony A. Slieman ◽  
Wayne L. Nicholson
Keyword(s):  
Bacillus Subtilis ◽  
Uv Irradiation ◽  
Double Strand Breaks ◽  
Single Strand ◽  
Complex Spectrum ◽  
Cyclobutane Pyrimidine Dimers ◽  
Strand Breaks ◽  
Single Strand Breaks ◽  
Pyrimidine Dimers ◽  
Solar Uv

ABSTRACT The loss of stratospheric ozone and the accompanying increase in solar UV flux have led to concerns regarding decreases in global microbial productivity. Central to understanding this process is determining the types and amounts of DNA damage in microbes caused by solar UV irradiation. While UV irradiation of dormant Bacillus subtilis endospores results mainly in formation of the “spore photoproduct” 5-thyminyl-5,6-dihydrothymine, genetic evidence indicates that an additional DNA photoproduct(s) may be formed in spores exposed to solar UV-B and UV-A radiation (Y. Xue and W. L. Nicholson, Appl. Environ. Microbiol. 62:2221–2227, 1996). We examined the occurrence of double-strand breaks, single-strand breaks, cyclobutane pyrimidine dimers, and apurinic-apyrimidinic sites in spore DNA under several UV irradiation conditions by using enzymatic probes and neutral or alkaline agarose gel electrophoresis. DNA from spores irradiated with artificial 254-nm UV-C radiation accumulated single-strand breaks, double-strand breaks, and cyclobutane pyrimidine dimers, while DNA from spores exposed to artificial UV-B radiation (wavelengths, 290 to 310 nm) accumulated only cyclobutane pyrimidine dimers. DNA from spores exposed to full-spectrum sunlight (UV-B and UV-A radiation) accumulated single-strand breaks, double-strand breaks, and cyclobutane pyrimidine dimers, whereas DNA from spores exposed to sunlight from which the UV-B component had been removed with a filter (“UV-A sunlight”) accumulated only single-strand breaks and double-strand breaks. Apurinic-apyrimidinic sites were not detected in spore DNA under any of the irradiation conditions used. Our data indicate that there is a complex spectrum of UV photoproducts in DNA of bacterial spores exposed to solar UV irradiation in the environment.

UV-induzierte Brüche in 5-Bromuracil-substituierter DNS des Phagen T1 / UV-Induced Strand Breaks in 5-Bromouracil Substituted DNA of Phage T1

1970 ◽  
Vol 25 (9) ◽  
pp. 1037-1042 ◽  
Author(s):  
G. Stephan ◽  
H. G. Miltenburger ◽  
G. Hotz
Keyword(s):  
Biological Activity ◽  
Uv Irradiation ◽  
Uv Light ◽  
Double Strand Breaks ◽  
Single Strand ◽  
Radical Scavenger ◽  
Strand Breaks ◽  
Single Strand Breaks ◽  
Phage Dna ◽  
Site Of Action

Phage Tl and BU-Τ1 (phage DNA substituted with 5-bromouracil) were inactivated by UV-light (2537 A). After irradiation DNA was extracted and its sedimentation behaviour studied by zone centrifugation in neutral and alkaline sucrose gradients, respectively. In the DNA of unsubstituted phage no double-strand breaks and only a small number of single-strand breaks per inactivation dose could be detected after high UV-doses. However, after irradiation of phage BU-T1 double- and single-strand breaks were observed at an increased rate. UV-irradiation in the presence of a radical scavenger (0.01 M cysteamine) prevented the occurrence of double- but not of single strand breaks. The relevance of these breaks attributable to BU-incorporation for the biological activity (plaque forming ability) of the phage and the site of action of cysteamine are discussed.

scholarly journals γH2AX in the S Phase After UV Irradiation Corresponds to DNA Replication and Not to the Extent of DNA Damage

2019 ◽  
Author(s):  
Shivnarayan Dhuppar ◽  
Sitara Roy ◽  
Aprotim Mazumder
Keyword(s):  
Dna Damage ◽  
Uv Irradiation ◽  
S Phase ◽  
Double Strand Breaks ◽  
Dna Double Strand Breaks ◽  
Cyclobutane Pyrimidine Dimers ◽  
Environmental Mutagen ◽  
Strand Breaks ◽  
Pyrimidine Dimers ◽  
A Cell

AbstractUltraviolet (UV) radiation is a major environmental mutagen. Exposure to UV leads to a sharp peak of γH2AX – the phosphorylated form of a histone variant H2AX – in the S phase within an asynchronous population of cells. γH2AX is often considered as a definitive marker of DNA damage inside a cell. In this report we show that γH2AX in the S phase cells after UV irradiation does not report on the extent of primary DNA damage in the form of cyclobutane pyrimidine dimers or on the extent of its secondary manifestations as DNA double strand breaks or in the inhibition of global transcription. Instead γH2AX in the S phase corresponds to the sites of active replication at the time of UV irradiation – despite which, the cells complete the replication of their genomes and arrest within the G2 phase. Moreover, cells in all the phases of the cell cycle develop similar levels of DNA damage. Our study suggests that it is not DNA damage but the response elicited, which peaks in the S phase upon UV damage.

scholarly journals DNA DAMAGE AND REPAIR IN EUKARYOTIC CELLS

Genetics ◽  
1974 ◽  
Vol 78 (1) ◽  
pp. 139-148
Author(s):  
R B Painter
Keyword(s):  
Ionizing Radiation ◽  
Excision Repair ◽  
Double Strand Breaks ◽  
Single Strand ◽  
Premature Aging ◽  
Cross Linking ◽  
Base Damage ◽  
Strand Breaks ◽  
Single Strand Breaks ◽  
Post Replication Repair

ABSTRACT Damage in DNA after irradiation can be classified into five kinds: base damage, single-strand breaks, double-strand breaks, DNA-DNA cross-linking, and DNA-protein cross-linking. Of these, repair of base damage is the best understood. In eukaryotes, at least three repair systems are known that can deal with base damage: photoreactivation, excision repair, and post-replication repair. Photoreactivation is specific for UV-induced damage and occurs widely throughout the biosphere, although it seems to be absent from placental mammals. Excision repair is present in prokaryotes and in animals but does not seem to be present in plants. Post-replication repair is poorly understood. Recent reports indicate that growing points in mammalian DNA simply skip past UV-induced lesions, leaving gaps in newly made DNA that are subsequently filled in by de novo synthesis. Evidence that this concept is oversimplified or incorrect is presented.—Single-strand breaks are induced by ionizing radiation but most cells can rapidly repair most or all of them, even after supralethal doses. The chemistry of the fragments formed when breaks are induced by ionizing radiation is complex and poorly understood. Therefore, the intermediate steps in the repair of single-strand breaks are unknown. Double-strand breaks and the two kinds of cross-linking have been studied very little and almost nothing is known about their mechanisms for repair.—The role of mammalian DNA repair in mutations is not known. Although there is evidence that defective repair can lead to cancer and/or premature aging in humans, the relationship between the molecular defects and the diseased state remains obscure.

scholarly journals γH2AX in the S Phase after UV Irradiation Corresponds to DNA Replication and Does Not Report on the Extent of DNA Damage

2020 ◽  
Vol 40 (20) ◽  
Author(s):  
Shivnarayan Dhuppar ◽  
Sitara Roy ◽  
Aprotim Mazumder
Keyword(s):  
Dna Damage ◽  
Uv Irradiation ◽  
S Phase ◽  
Dna Double Strand Breaks ◽  
Cyclobutane Pyrimidine Dimers ◽  
Environmental Mutagen ◽  
Strand Breaks ◽  
Pyrimidine Dimers ◽  
Replication Sites ◽  
A Cell

ABSTRACT Ultraviolet (UV) radiation is a major environmental mutagen. Exposure to UV leads to a sharp peak of γH2AX, the phosphorylated form of the histone variant H2AX, in the S phase within an asynchronous population of cells. γH2AX is often considered a definitive marker of DNA damage inside a cell. In this report, we show that γH2AX in the S-phase cells after UV irradiation reports neither on the extent of primary DNA damage in the form of cyclobutane pyrimidine dimers nor on the extent of its secondary manifestations in the form of DNA double-strand breaks or in the inhibition of global transcription. Instead, γH2AX in the S phase corresponds to the sites of active replication at the time of UV irradiation. This accumulation of γH2AX at replication sites slows down the replication. However, the cells do complete the replication of their genomes and arrest within the G2 phase. Our study suggests that it is not DNA damage, but the response elicited, which peaks in the S phase upon UV irradiation.

Experimentelle Hinweise auf intramolekulare Energieleitung in der hybriden DNA von Bacillus subtilis nach Bestrahlung mit langwelligem UV-Licht / Experimental Evidence for Intramolecular Energy Transfer in Hybrid DNA of B. subtilis after Irradiation with Long Wavelength UV

1972 ◽  
Vol 27 (6) ◽  
pp. 708-713 ◽  
Author(s):  
W. Köhnlein ◽  
F. Mönkehaus
Keyword(s):  
Bacillus Subtilis ◽  
Energy Transfer ◽  
Experimental Evidence ◽  
Analytical Ultracentrifugation ◽  
Single Strand ◽  
Intramolecular Energy Transfer ◽  
Strand Breaks ◽  
Long Wavelength ◽  
Single Strand Breaks ◽  
Hybrid Dna

Investigations on hybrid DNA of B. subtilis after irradiation with long wavelength UV (313 nm) indicate that single strand breaks are produced in the T-strand. These lesions are not observed in normal DNA. Since the action of diffusible photoproducts could be excluded the occurrence of single strand breaks in the T-strand may be due to intramolecular energy transfer. Measuring the breakage rates for the T- and B-strand by employing analytical ultracentrifugation it was found that up to 5% of the energy absorbed in the B-strand can be transferred to the T-strand and causes there single strand breaks. The breakage rates per erg-mm- 2 for single strand breaks after long wavelength UV are determined to be aT = 0.5 · 10-4 and aB = 10 · 10-4 breaks/106 Dalton for the T- and B-strand of hybrid DNA respectively.

Matching of single-strand breaks to form double-strand breaks in DNA

Biopolymers ◽  
1969 ◽  
Vol 7 (5) ◽  
pp. 681-693 ◽  
Author(s):  
David Freifelder ◽  
Bruce Trumbo
Keyword(s):  
Double Strand Breaks ◽  
Single Strand ◽  
Strand Breaks ◽  
Single Strand Breaks

Less Repair of Pyrimidine Dimers and Single-Strand Breaks in Genes by Scid Cells

1999 ◽  
Vol 264 (3) ◽  
pp. 878-882 ◽  
Author(s):  
Rudaina H. Alrefai ◽  
E.Jeffrey Beecham ◽  
Vilhelm A. Bohr ◽  
Patricia J. Gearhart
Keyword(s):  
Single Strand ◽  
Strand Breaks ◽  
Single Strand Breaks ◽  
Pyrimidine Dimers ◽  
Scid Cells

scholarly journals Single Strand Breaks Induced in DNA of Bacillus subtilis Cells by Mild Heating

1977 ◽  
Vol 43 (6) ◽  
pp. 779-779
Author(s):  
Aritsune UCHIDA ◽  
Yoshihiko SAKO ◽  
Hajime KADOTA
Keyword(s):  
Bacillus Subtilis ◽  
Single Strand ◽  
Strand Breaks ◽  
Single Strand Breaks ◽  
I Cells

Gamma-ray induced strand breakage of Bacillus subtilis DNA irradiated in vivo

1971 ◽  
Vol 17 (5) ◽  
pp. 575-583 ◽  
Author(s):  
David L. Dugle ◽  
Janet R. Dugle
Keyword(s):  
Bacillus Subtilis ◽  
Survival Data ◽  
Gamma Ray ◽  
Double Strand Breaks ◽  
Single Strand ◽  
Subtilis Strain ◽  
Strand Breaks ◽  
Strand Breakage ◽  
Total Dna

Evidence is presented for the isolation of DNA having a molecular weight of 31 ± 5 × 108 from Bacillus subtilis strain 23 Thy− cells. This accounts for the total DNA content of the genome. Single-strand and double-strand breaks induced by 60Co gamma rays were measured by sucrose density centrifugation. The occurrence of repair of single-strand and possibly double-strand breaks at 0 °C is inferred from survival data and the effects of pre- or post-irradiation heating.

Sign in / Sign up

Export Citation Format

Share Document