Sister-Chromated Exchanges as a Measure of Damage Produced by Visible Light on BrdUrd-Substituted Chromosomes
We have studied the effect of visible light irradiation on BrdUrd-substituted chromosomes in Allium cepa L. meristem cells by measuring the yields of SCEs. The efficiency of this treatment in provoking SCEs is clearly dependent on the cell cycle time in which damage occurs, having obtained the highest frequencies when VL exposure coincides with the initiation of the S phase. Nitrogen atmosphere during irradiation reduces SCE frequencies, suggesting that some oxidizing radical species could be involved in the chemical reactions producing lesions that ultimately lead to SCE formation. These results are discussed with respect to the hypothesis that SCEs arise as a consequence of the passage of a damaged DNA through the replication process.
fluorescence plus Giemsa
Chinese hamster ovary
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