Skip to main content
U.S. Department of Energy
Office of Scientific and Technical Information

Direct evidence for the role of incorporated BUdR in the induction of sister chromatid exchanges

Journal Article · · Exp. Cell Res.; (United States)
The level of bromodeoxyuridine (BUdR) substitution for thymidine (dThd) in nascent DNA of Chinese hamster cells increases rapidly with increasing BUdR concentration at low BUdR/base pair (BU/bp) ratios and then increases much more slowly at higher ratios. The relationship between percentage substitution and BU/bp indicates that BUdR competes with dThd for incorporation into DNA and that BUdR concentration has no effect on the effective dThd/base pair ratio in these cells. Equal amounts of BUdR are incorporated during both the first and second cell cycles (S phases) after provision of the dThd analog. Incorporation of BUdR induces sister chromatid exchanges (SCEs), and induction appears to occur during the cell cycle (S phase) in which incorporation occurs, with incorporated BUdR from previous cycles having little effect. BUdR-induced SCE frequencies are linearly proportional to the percentage substitution of BUdR for dThd. Extrapolation to zero substitution indicates that SCEs occur spontaneously at a frequency of 0.045 per chromosome per cycle, and that many so-called spontaneous SCEs are actually induced by BUdR.
Research Organization:
Univ. of California, Livermore
OSTI ID:
5368354
Journal Information:
Exp. Cell Res.; (United States), Journal Name: Exp. Cell Res.; (United States) Vol. 117; ISSN ECREA
Country of Publication:
United States
Language:
English