Deamination of cytosine to uracil is the most common promutagenic change in DNA, and it is greatly increased at the elevated growth temperatures of hyperthermophilic archaea. If not repaired to cytosine prior to replication, uracil in a template strand directs incorporation of adenine, generating a G.C --> A.U transition mutation in half the progeny. Surprisingly, genomic analysis of archaea ha...

The effect of the nucleic acid bases adenine, cytosine, thymine, uracil, and 5-bromo-uracil on the light-induced reduction of methylene blue in dimethylsulfoxide has been investigated by means of ESR and optical absorption studies. It could be shown that the nucleic acid bases act as electron acceptors. The experimentally obtained electron affinities are of the following order: cytosine > adeni...

After gamma irradiation of cytosine in aerated aqueous solution, yields of chemical radiation products belonging to the deamination pathway were measured. Primary stable radiolysis products, such as 5,6-dihydroxy-5,6-dihydro-uracil cis and trans forms, were present with G values lower than those obtained in the radiolysis of uracil irradiated under the same conditions. Cytosine had Gamma Irradi...

We have identified three lesions rather than cyclobutane dimers which alter the properties of UV-irradiated poly(dC) as a template for E.coli DNA polymerase I, and have characterised these lesions with respect to their coding properties, rates of formation and decay, and their sensitivity to uracil DNA glycosylase. Our results lead us to conclude that these lesions are (1) cytosine hydrates, wh...

The stereoselective synthesis of some 3’-deoxy-3’-C-methyl pyrimidine nucleosides is reported. studied modifications concern the inversion configuration in 2’-position as well introduction fluoro and azido substituents. corresponding arabinonucleoside 2’-substituted ribonucleoside analogs uracil cytosine have been obtained fully characterized. Attempts to introduce substituents with at C-2’ are...

1. When DNA is hydrolysed with formic acid for 30min. at 175 degrees and the hydrolysate is chromatographed on paper with propan-2-ol-2n-hydrochloric acid, in addition to expected ultraviolet-absorbing spots corresponding to guanine, adenine, cytosine and thymine, an ultraviolet-absorbing region with R(F) similar to that of uracil can be detected. Uracil was separated from this region and ident...

Bisulfite genomic sequencing is a widely used technique for analyzing cytosine-methylation of DNA. By treating DNA with bisulfite, cytosine residues are deaminated to uracil, while leaving 5-methylcytosine largely intact. Subsequent PCR and nucleotide sequence analysis permit unequivocal determination of the methylation status at cytosine residues. A major caveat associated with the currently p...

Radiolysis products resulting from the deamination pathway were isolated and identified after irradiation of cytosine by gamma rays in neutral aqueous solutions. They were identical to those identified in uracil radiolysis i. e. 5,6-dihydroxy-5,6-dihydro-uracil (cis and trans forms), iso-dialuric acid, alloxan, 5-hydroxy-hydantoin, parabanic acid and oxaluric acid. The absence of 4,4'-di-iso-ba...