Induction of mutation and chromosome damage by excess bases and nucleosides

The studies reported in this communication were conducted to determine if naturally occurring cell constituents could themselves cause mutation. All the bases and their corresponding nucleosides have been shown in culture to produce chromosome damage in P388 mouse lymphoma and Chinese hamster ovary cells (CHO) and adenosine has produced an increased incidence of sister chromatid exchanges in CHO cells. In addition thymidine has produced an increase in V79 cells resistant to 8-azaguanine and ouabain, although no effects were seen in six strains of Salmonella typhimurium. Such damage probably arises as a result of imbalanced DNA-precursor pools. Thus mutagenic events may arise by mechanisms unrelated to direct alterations of DNA.