Thymidine-methyl-3 H and either formate-' @ C or @ C were added to incubations containing various concentrations of 5-fluorouracil. The thymine in DNA was isolated, and precursor incorporation was determined by dual-label liquid scintillation counting. MATERIALS AND METHODS The methods used in this study have been previously described (12). In summary, tissues obtained from patients who had not...

The pattern of formate-Cl4 incorporation by Ehrlich ascites tumor cells has been found to be remarkably different in vitro from the pattern of incorporation in vivo (3-5). Thus, after incubation of cells with formate-Cl4 in vitro, the specific activity of the DNA thymine was 10 to 30 times higher than that of the DNA purines. In contrast, after incorporation of formateCl4 by these cells in viva...

The incorporation of pyrimidines into nucleic acids in vivo is increased by inhibition of pyrimidine catabolism with diazouracil. The utilization of iodouracil or thymine for DNA synthesis can be increased approximately 20-fold by simultaneous administration of diazouracil and a purine deoxyribonucleoside. The incorporation of iodouracil and thymine, when administered at high doses, is elevated...

Evidence for active DNA demethylation in vertebrates is accumulating, but the mechanisms and enzymes remain unclear. Using zebrafish embryos we provide evidence for 5-methylcytosine (5-meC) removal in vivo via the coupling of a 5-meC deaminase (AID, which converts 5-meC to thymine) and a G:T mismatch-specific thymine glycosylase (Mbd4). The injection of methylated DNA into embryos induced a pot...

Mercury ion (Hg2+) is recognized as one of the most toxic metal ions for the environment and for human health. Techniques utilized in the detection of Hg2+ are an important factor. Herein, a simple thymine was successfully employed as the surface enhanced Raman spectroscopy sensor for Hg2+ ion detection. The limit of detection (LOD) of the developed sensor is better than 0.1 nM (0.02 ppb). This...

Bacteriophage T5 induces a deoxyuridine B’-triphosphate nucleotidohydrolase (dUTPase) activity during infection of Escherichiu coli. A T5 mutant (T5 dut) unable to induce this dUTPase activity has been isolated. Although this mutant is viable, the E. coli dUTPase activity is not sufficiently active to exclude uracil from the progeny DNA and about 3% of the thymine is replaced by uracil. When th...

After UV excitation, gas phase thymine returns to a ground state in 5 to 7 ps, showing multiple time constants. There is no consensus on the assignment of these processes, with a dispute between models claiming that thymine is trapped either in the first (S₁) or in the second (S₂) excited states. In the present study, a nonadiabatic dynamics simulation of thymine is performed on the basis of AD...

For DNA differential diagnosis of human Taenia cestodes, a base excision sequence scanning thymine-base method using the cytochrome c oxidase subunit I and cytochrome b genes as targets was used. The characteristic thymine-base peak profiles provide four distinct types, unique for T. saginata, T. asiatica, and two genotypes of T. solium. This approach provides a useful tool for the identificati...

A Zn(II) macrocyclic complex with appended quinoline is a bifunctional recognition agent that uses both the Zn(II) center and the pendent aromatic group to bind to thymine in bulges with good selectivity over DNA containing G, C or A bulges. Spectroscopic studies show that the stem containing the bulge stays largely intact in a DNA hairpin with the Zn(II) complex bound to the thymine bulge.

Crude extracts of normal human diploid fibroblasts and of human peripheral blood lymphocytes excise thymine dimers from purified ultraviolet-irradiated DNA, or from the DNA presumably present as chromatin in unfractionated cell-free preparations of cells that had been labeled with [3H]thymidine. Extracts of xeroderma pigmentosum cells from complementation groups A, C, and D also excise thymine ...