Biomaterial Database

Excision of pyrimidine dimers from the DNA of Neurospora. 1986

H Macleod, and D Stadler

Germinated conidia of Neurospora have been monitored for their ability to excise pyrimidine dimers. Dimer concentration was measured in DNA extracted immediately after UV treatment, and it was compared to that of DNA from cells which had a post-UV incubation before extraction. Two methods were used to assay dimer level in DNA: measurement of the number of single-strand breaks (as revealed in alkaline sucrose gradients) produced by a dimer-specific endonuclease; monitoring the ability to compete for binding to dimer-specific antibodies in a radioimmunoassay. Both methods showed efficient excision of dimers by wild-type and by uvs-2, even though an earlier study had reported that uvs-2 was unable to excise dimers. UV-induced mutation shows a dose-rate effect: acute UV yields several times as many mutations as does the same dose of chronic UV. There is a parallel effect on dimer accumulation. The concentration of dimers at the conclusion of the UV treatment shows a strong correlation with the resultant mutation frequency.

UI	MeSH Term	Description	Entries
D009491	Neurospora	A genus of ascomycetous fungi, family Sordariaceae, order SORDARIALES, comprising bread molds. They are capable of converting tryptophan to nicotinic acid and are used extensively in genetic and enzyme research. (Dorland, 27th ed)	Neurosporas
D011740	Pyrimidine Dimers	Dimers found in DNA chains damaged by ULTRAVIOLET RAYS. They consist of two adjacent PYRIMIDINE NUCLEOTIDES, usually THYMINE nucleotides, in which the pyrimidine residues are covalently joined by a cyclobutane ring. These dimers block DNA REPLICATION.	Cyclobutane Pyrimidine Dimer,Cyclobutane-Pyrimidine Dimer,Cytosine-Thymine Dimer,Pyrimidine Dimer,Thymine Dimer,Thymine Dimers,Cyclobutane-Pyrimidine Dimers,Cytosine-Thymine Dimers,Thymine-Cyclobutane Dimer,Thymine-Thymine Cyclobutane Dimer,Cyclobutane Dimer, Thymine-Thymine,Cyclobutane Dimers, Thymine-Thymine,Cyclobutane Pyrimidine Dimers,Cytosine Thymine Dimer,Cytosine Thymine Dimers,Pyrimidine Dimer, Cyclobutane,Pyrimidine Dimers, Cyclobutane,Thymine Cyclobutane Dimer,Thymine Thymine Cyclobutane Dimer,Thymine-Cyclobutane Dimers,Thymine-Thymine Cyclobutane Dimers
D004260	DNA Repair	The removal of DNA LESIONS and/or restoration of intact DNA strands without BASE PAIR MISMATCHES, intrastrand or interstrand crosslinks, or discontinuities in the DNA sugar-phosphate backbones.	DNA Damage Response
D004262	DNA Restriction Enzymes	Enzymes that are part of the restriction-modification systems. They catalyze the endonucleolytic cleavage of DNA sequences which lack the species-specific methylation pattern in the host cell's DNA. Cleavage yields random or specific double-stranded fragments with terminal 5'-phosphates. The function of restriction enzymes is to destroy any foreign DNA that invades the host cell. Most have been studied in bacterial systems, but a few have been found in eukaryotic organisms. They are also used as tools for the systematic dissection and mapping of chromosomes, in the determination of base sequences of DNAs, and have made it possible to splice and recombine genes from one organism into the genome of another. EC 3.21.1.	Restriction Endonucleases,DNA Restriction Enzyme,Restriction Endonuclease,Endonuclease, Restriction,Endonucleases, Restriction,Enzymes, DNA Restriction,Restriction Enzyme, DNA,Restriction Enzymes, DNA
D004271	DNA, Fungal	Deoxyribonucleic acid that makes up the genetic material of fungi.	Fungal DNA
D004307	Dose-Response Relationship, Radiation	The relationship between the dose of administered radiation and the response of the organism or tissue to the radiation.	Dose Response Relationship, Radiation,Dose-Response Relationships, Radiation,Radiation Dose-Response Relationship,Radiation Dose-Response Relationships,Relationship, Radiation Dose-Response,Relationships, Radiation Dose-Response
D014466	Ultraviolet Rays	That portion of the electromagnetic spectrum immediately below the visible range and extending into the x-ray frequencies. The longer wavelengths (near-UV or biotic or vital rays) are necessary for the endogenous synthesis of vitamin D and are also called antirachitic rays; the shorter, ionizing wavelengths (far-UV or abiotic or extravital rays) are viricidal, bactericidal, mutagenic, and carcinogenic and are used as disinfectants.	Actinic Rays,Black Light, Ultraviolet,UV Light,UV Radiation,Ultra-Violet Rays,Ultraviolet Light,Ultraviolet Radiation,Actinic Ray,Light, UV,Light, Ultraviolet,Radiation, UV,Radiation, Ultraviolet,Ray, Actinic,Ray, Ultra-Violet,Ray, Ultraviolet,Ultra Violet Rays,Ultra-Violet Ray,Ultraviolet Black Light,Ultraviolet Black Lights,Ultraviolet Radiations,Ultraviolet Ray