DNA ethylations induced by ethylnitrosourea in the wild type, cdc4 and cdc7 strains of Saccharomyces cerevisiae

The experiments reported here have investigated the inductionof ethylations to DNA in yeast cells exposed to the chemicalmutagen ethylnitrosourea. A similar level of alkylation wasseen at the N⁷ and O⁶ of guanine and at the N³ of adenine ineither log phase cells or in temperature-sensitive cdc4 andcdc7 cells growth arrested at their specific G₁ positions. Hencethe changes in chromosome structure associated with the abovecdc phenotypes do not modify the amount of DNA damage inducedby ethylnitrosourea. ¹To whom reprint requests should be addressed