Uracil may arise in DNA as a result of deamination of cytosine or through incorporation of dUMP instead of dTMP during replication. We have studied the steady-state levels of uracil in the DNA of primary cells and mouse embryonic fibroblast (MEF) cell lines from mice deficient in the Ung uracil-DNA glycosylase. The results show that the levels of uracil in the DNA of Ung(-/-) cells strongly dep...

The tendencies described in this work were revealed in the course of examination of adenine and uracil distribution in the mRNA encoding sequence. The study also discusses the usage of codons occupied by the amino acid arginine in the table of the universal genetic code. All of the described tendencies are qualitative, so neither sophisticated methods nor cumbersome calculations are necessary t...

ONHERITABLE repair of a mutant phenotype resulting from errors in translation was first described by BENZER and CHAMPE (1961) for rZZ mutants of phage T4. These mutants are ordinarily unable to grow on Escherichia coli strain KB, but can grow on strain B. Treatment of infected KB cells with 5-fluorouracil (5FU) resulted in a large increase in phage yield with certain rZZ mutants, yet the progen...

A requirement for carbon dioxide or bicarbonate has been demonstrated for the growth and survival of the Jensen, JA-1, and JA-2 sarcomas in vitro. When the cells were grown in the presenee of C140~, isotope was isolated in incorporated aspartic acid, glutamic acid, and proline as well as in the purines and pyrimidines. Although the relative specific activity of the purines and thymine was appro...

Uracil appears in DNA as a result of cytosine deamination and by incorporation from the dUTP pool. As potentially mutagenic and deleterious for cell regulation, uracil must be removed from DNA. The major pathway of its repair is initiated by uracil-DNA glycosylases (UNG), ubiquitously found enzymes that hydrolyze the N-glycosidic bond of deoxyuridine in DNA. This review describes the current un...

Uracil-DNA glycosylase, the enzyme responsible for the removal of uracil from DNA (1), is directly involved in mutation avoidance (2). Indeed, it is likely to prevent transition mutations by removing uracil that results from deamination of cytosine. It has been proposed that the removal of misincorporated uracil by uracil-DNA glycosylase also plays an indirect role in correction of replication ...

Deamination of cytosine residues contributes to the appearance of uracil in DNA. Uracil DNA glycosylase (UDG) initiates uracil excision repair to safeguard the genomic integrity. To study the mechanism of uracil excision in mycobacteria (organisms with G+C rich genomes), we have purified UDG from Mycobacterium smegmatis by more than 3000-fold. The molecular mass of M. smegmatis UDG, as determin...

The pyrimidine-deficient mutant (1298) of Neurospora crassa, utilizes erotic acid, uracil, uridine, or cytidine for growth, but neither cytosine nor thymine (1). It seems likely, therefore, that this mutant can convert erotic acid and uracil to the pyrimidine bases of ribonucleic acid and deoxyribonucleic acid, and can utilize the nucleoside directly for ribonucleic acid biosynthesis and for co...