The effect of hydroxyurea on the mechanism of DNA synthesis in the yeast Saccharomyces cerevisiae.

Newly synthesised DNA molecules the same size as replicons (7 million-60 million daltons) accumulate in yeast cells treated with hydroxyurea. During prolonged incubation in low concentrations of the drug, there is a large accumulation of these molecules without any corresponding increase in their molecular weight. On release from the inhibtion the molecules are converted to large molecular weight DNA. These observations are consistent with an inhibition by hydroxyurea of the joining of completed replicons. In addition, newly synthesised DNA molecules the size of yeast Okazaki fragments also accumulate in cells treated with hydroxyurea.