Ultraviolet light induced thymine dimers and repair processes in the alga Eudorina elegans

1972 ◽  
Vol 18 (12) ◽  
pp. 1809-1815 ◽  
Author(s):  
C. L. Kemp ◽  
M. S. Tsao ◽  
G. Thorson
Keyword(s):  
Visible Light ◽  
Ultraviolet Light ◽  
Green Alga ◽  
Uv Irradiation ◽  
Excision Repair ◽  
Uv Exposure ◽  
Dark Repair ◽  
Thymine Dimer ◽  
Thymine Dimers ◽  
Cellular Dna

A fraction of the cellular DNA of the colonial green alga Eudorina elegans strain 1193 can be specifically labeled with 3H-thymidine but not by 3H-thymine. Ultraviolet (UV) irradiation of E. elegans leads to the production of thymine dimers as determined by extraction, hydrolysis, and chromatography of 3H-thymidine-labeled cells. Removal of dimers occurs by processes involving visible light (photoreactivation), but dark repair (excision repair) has not been detected in the labeled fraction. A relationship between UV exposure and thymine dimer production has been determined.

EVIDENCE FOR DARK REPAIR OF FAR ULTRAVIOLET LIGHT DAMAGE IN THE BLUE-GREEN ALGA, GLOEOCAPSA ALPICOLA

1979 ◽  
Vol 29 (3) ◽  
pp. 543-547 ◽  
Author(s):  
Edwin Williams ◽  
Joan Lambert ◽  
Philip O'Brien ◽  
James A. Houghton
Keyword(s):  
Ultraviolet Light ◽  
Green Alga ◽  
Blue Green Alga ◽  
Light Damage ◽  
Dark Repair ◽  
Far Ultraviolet

Ultraviolet sensitivity and photoproducts in spore-like bodies of an excision-repair-deficient and dipicolinic-acid-less strain of Bacillus subtilis

1975 ◽  
Vol 21 (7) ◽  
pp. 1129-1132 ◽  
Author(s):  
N. Munakata ◽  
P. C. Fitz-James ◽  
I. E. Young
Keyword(s):  
Bacillus Subtilis ◽  
Ultraviolet Light ◽  
Uv Irradiation ◽  
Excision Repair ◽  
Dipicolinic Acid ◽  
Subtilis Strain ◽  
Sporulation Medium ◽  
Ultraviolet Sensitivity ◽  
Cyclobutane Dimers ◽  
Spore Photoproduct

Bacillus subtilis strain UVS-42DPA is defective in both excision-repair capability and dipicolinic acid (DPA) accumulation. In sporulation medium, it forms spore-like bodies, which are as sensitive to ultraviolet light (UV) as the vegetative cells and produce mostly cyclobutane dimers instead of "spore photoproduct" upon UV irradiation. The results suggest that the drastic change in the photochemical reactivity of DNA during sporulation might be induced and (or) maintained by the accumulation of DPA.

scholarly journals Thymine dissociation and dimer formation: A Raman and synchronous fluorescence spectroscopic study

2021 ◽  
Vol 118 (6) ◽  
pp. e2025263118
Author(s):  
Anushka Nagpal ◽  
Dinesh Dhankhar ◽  
Thomas C. Cesario ◽  
Runze Li ◽  
Jie Chen ◽  
...  
Keyword(s):  
Raman Spectra ◽  
Uv Irradiation ◽  
Spectroscopic Data ◽  
Irradiation Dose ◽  
Synchronous Fluorescence ◽  
Dimer Formation ◽  
Thymine Dimer ◽  
Calf Thymus ◽  
Thymine Dimers ◽  
Bacteria Inactivation

In this study, absorption, fluorescence, synchronous fluorescence, and Raman spectra of nonirradiated and ultraviolet (UV)-irradiated thymine solutions were recorded in order to detect thymine dimer formation. The thymine dimer formation, as a function of irradiation dose, was determined by Raman spectroscopy. In addition, the formation of a mutagenic (6-4) photoproduct was identified by its synchronous fluorescence spectrum. Our spectroscopic data suggest that the rate of conversion of thymine to thymine dimer decreases after 20 min of UV irradiation, owing to the formation of an equilibrium between the thymine dimers and monomers. However, the formation of the (6-4) photoproduct continued to increase with UV irradiation. In addition, the Raman spectra of nonirradiated and irradiated calf thymus DNA were recorded, and the formation of thymine dimers was detected. The spectroscopic data presented make it possible to determine the mechanism of thymine dimer formation, which is known to be responsible for the inhibition of DNA replication that causes bacteria inactivation.

scholarly journals Excision of Oxidatively Generated Guanine Lesions by Competitive DNA Repair Pathways

2021 ◽  
Vol 22 (5) ◽  
pp. 2698
Author(s):  
Vladimir Shafirovich ◽  
Nicholas E. Geacintov
Keyword(s):  
Excision Repair ◽  
Dna Lesions ◽  
Dna Templates ◽  
Circular Dna ◽  
Damage Sensing ◽  
Cell Extracts ◽  
Dna Base ◽  
Nucleotide Excision ◽  
Repair Pathways ◽  
Cellular Dna

The base and nucleotide excision repair pathways (BER and NER, respectively) are two major mechanisms that remove DNA lesions formed by the reactions of genotoxic intermediates with cellular DNA. It is generally believed that small non-bulky oxidatively generated DNA base modifications are removed by BER pathways, whereas DNA helix-distorting bulky lesions derived from the attack of chemical carcinogens or UV irradiation are repaired by the NER machinery. However, existing and growing experimental evidence indicates that oxidatively generated DNA lesions can be repaired by competitive BER and NER pathways in human cell extracts and intact human cells. Here, we focus on the interplay and competition of BER and NER pathways in excising oxidatively generated guanine lesions site-specifically positioned in plasmid DNA templates constructed by a gapped-vector technology. These experiments demonstrate a significant enhancement of the NER yields in covalently closed circular DNA plasmids (relative to the same, but linearized form of the same plasmid) harboring certain oxidatively generated guanine lesions. The interplay between the BER and NER pathways that remove oxidatively generated guanine lesions are reviewed and discussed in terms of competitive binding of the BER proteins and the DNA damage-sensing NER factor XPC-RAD23B to these lesions.

scholarly journals Signal Amplification in an Optical and Dielectric Biosensor Employing Liquid Crystal-Photopolymer Composite as the Sensing Medium

Biosensors ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 81
Author(s):  
Hassanein Shaban ◽  
Shih-Chun Yen ◽  
Mon-Juan Lee ◽  
Wei Lee
Keyword(s):  
Dielectric Constant ◽  
Liquid Crystal ◽  
Uv Irradiation ◽  
Signal Amplification ◽  
Limit Of Detection ◽  
Optical Signal ◽  
Uv Exposure ◽  
Dielectric Anisotropy ◽  
Optical Texture ◽  
Potential Development

An optical and dielectric biosensor based on a liquid crystal (LC)–photopolymer composite was established in this study for the detection and quantitation of bovine serum albumin (BSA). When the nematic LC E7 was doped with 4-wt.% NOA65, a photo-curable prepolymer, and photopolymerized by UV irradiation at 20 mW/cm2 for 300 s, the limit of detection determined by image analysis of the LC optical texture and dielectric spectroscopic measurements was 3400 and 88 pg/mL for BSA, respectively, which were lower than those detected with E7 alone (10 μg/mL BSA). The photopolymerized NOA65, but not the prepolymer prior to UV exposure, contributed to the enhanced optical signal, and UV irradiation of pristine E7 in the absence of NOA65 had no effect on the optical texture. The effective tilt angle θ, calculated from the real-part dielectric constant ε’, decreased with increasing BSA concentration, providing strong evidence for the correlation of photopolymerized NOA65 to the intensified disruption in the vertically oriented LC molecules to enhance the optical and dielectric signals of BSA. The optical and dielectric anisotropy of LCs and the photo-curable dopant facilitate novel quantitative and signal amplification approaches to potential development of LC-based biosensors.

scholarly journals AtRAD1, a plant homologue of human and yeast nucleotide excision repair endonucleases, is involved in dark repair of UV damages and recombination

2000 ◽  
Vol 21 (6) ◽  
pp. 507-518 ◽  
Author(s):  
Francesca Gallego ◽  
Oliver Fleck ◽  
Anatoliy Li ◽  
Joanna Wyrzykowska ◽  
Bruno Tinland
Keyword(s):  
Nucleotide Excision Repair ◽  
Excision Repair ◽  
Dark Repair ◽  
Nucleotide Excision ◽  
Plant Homologue

Alteration of human cellular DNA by neutral red in the presence of visible light

1979 ◽  
Vol 66 (1) ◽  
pp. 95-98 ◽  
Author(s):  
William T. Speck ◽  
Regina M. Santella ◽  
Shari Brem ◽  
Herbert S. Rosenkranz
Keyword(s):  
Visible Light ◽  
Neutral Red ◽  
Cellular Dna

scholarly journals A Synthetic Interaction between CDC20 and RAD4 in Saccharomyces cerevisiae upon UV Irradiation

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Bernadette Connors ◽  
Lauren Rochelle ◽  
Asela Roberts ◽  
Graham Howard
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Nucleotide Excision Repair ◽  
Uv Irradiation ◽  
Double Mutant ◽  
Excision Repair ◽  
Strand Break ◽  
Anaphase Promoting Complex ◽  
End Joining ◽  
Ubiquitin Ligase Complex ◽  
Nucleotide Excision

Regulation of DNA repair can be achieved through ubiquitin-mediated degradation of transiently induced proteins. In Saccharomyces cerevisiae, Rad4 is involved in damage recognition during nucleotide excision repair (NER) and, in conjunction with Rad23, recruits other proteins to the site of damage. We identified a synthetic interaction upon UV exposure between Rad4 and Cdc20, a protein that modulates the activity of the anaphase promoting complex (APC/C), a multisubunit E3 ubiquitin ligase complex. The moderately UV sensitive Δrad4 strain became highly sensitive when cdc20-1 was present, and was rescued by overexpression of CDC20. The double mutant is also deficient in elicting RNR3-lacZ transcription upon exposure to UV irradiation or 4-NQO compared with the Δrad4 single mutant. We demonstrate that the Δrad4/cdc20-1 double mutant is defective in double strand break repair by way of a plasmid end-joining assay, indicating that Rad4 acts to ensure that damaged DNA is repaired via a Cdc20-mediated mechanism. This study is the first to present evidence that Cdc20 may play a role in the degradation of proteins involved in nucleotide excision repair.

scholarly journals Rare earth oxynitrides: Promising visible-light-driven photocatalysts for water splitting

2021 ◽  
Author(s):  
Shijia Jiang ◽  
Yanxin Liu ◽  
Jun Xu
Keyword(s):  
Rare Earth ◽  
Visible Light ◽  
Water Splitting ◽  
Ultraviolet Light ◽  
Energy Crisis ◽  
Potential Solution ◽  
Global Energy ◽  
Ultraviolet Light Irradiation ◽  
Visible Light Driven ◽  
Main Component

Photocatalytic water splitting is a potential solution for global energy crisis. However, most photocatalysts only respond to ultraviolet light irradiation, which is not the main component of sunlight. The photocatalysis...

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