The distribution of 5-bromodeoxyuridine in the DNA of polyoma-transformed mouse cells and some apparent effects on transcription

Abstract

The DNA of polyoma-transformed mouse cells grown in the presence of 5-bromodeoxyuridine (BUdR) was examined in neutral and alkaline CsCl gradients. All of the cells had incorporated BUdR into their DNA and no distinct classes of different degrees of substitution were observed. The reassociation kinetics of DNA containing tritiated BUdR demonstrated that the analog did not preferentially replace thymidine in either the repetitive or non-repetitive sequences. RNA-DNA saturation hybridization experiments using RNA extracted from cells grown in medium containing BUdR revealed an apparent reduction in the extent of non-repetitive DNA transcription compared with untreated control cells. The degree to which regulatory genes, as opposed to structural genes, is involved in this decrease cannot be determined from these data.