Induction of sister-chromatid exchanges (SCEs) by 5-fluorodeoxyuridine. The role of 5-bromodeoxyuridine incorporated into parental DNA.
The effect of thymidine (dT) and 5-fluorodeoxyuridine (FdU) on the frequency of sister-chromatid exchanges (SCEs) was examined in root-tip cells of Allium cepa. dT was unable to induce SCEs at all the concentrations tested. In contrast, FdU was efficient in the induction of SCEs. A nearly 3-fold increase in the frequency of SCEs was obtained with 5 X 10(-7) M FdU when it was given simultaneously with 5-bromodeoxyuridine (BrdU) for 2 consecutive cell cycles. Also, when FdU was present only for the first round of replication, the rate of SCEs in M2 chromosomes was notably higher than when it was given only during the second replication round. By analyzing M3 chromosomes treated during the second replication round with FdU the results also supported the hypothesis that the majority of the FdU-induced SCEs arise as a consequence of a higher rate of BrdU incorporation, and that most of them are formed when BrdU-containing strands are used as template for DNA synthesis.
Escalza
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P
Cortés
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Schvartzman
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JB
D001973:Bromodeoxyuridine / Q000378:metabolism / Q000633:toxicity*; D002453:Cell Cycle; D004261:DNA Replication; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D004357:Drug Synergism; D005467:Floxuridine / Q000633:toxicity*; D010944:Plants; D012854:Sister Chromatid Exchange / Q000187:drug effects*
D005467:Floxuridine; D001973:Bromodeoxyuridine