Unscheduled DNA synthesis in growing roots and stored embryos of Vicia faba after the action of maleic hydrazide and methyl methanesulphonate.
Growing roots of Vicia faba were treated with MH for 5 h, washed for 2 h and exposed to 3H-thymidine (3H-TdR) for additional 2-h periods at 7 h, 24 h and 32 h after the onset of MH treatment, to label DNA. As the replicative DNA synthesis was suppressed by HU, an enhancement of 3H-TdR incorporation into nuclear DNA above the control, as determined by microautoradiography, was considered to be due to unscheduled DNA synthesis induced by the mutagen. A significantly higher incorporation of 3H-TdR into DNA of MH-treated roots occurred, when labelling was applied 7 h after the MH action, whereas at 24 h only slight and at 32 h no enhancement of DNA labelling above control was registered. A 3-14-day storage with 50% water content of V. faba seeds exposed to MH or MMS resulted in a recovery from mutagen-induced chromosomal damage and a significantly higher incorporation of 3H-TdR into nuclear DNA. This supports the hypothesis that recovery from MH- and MMS-induced chromosomal damage is mediated by excision repair during seed storage.
Murín
G
G
Institute of Molecular and Subcellular Biology, Comenius University, Bratislava, Czechoslovakia.
D001345:Autoradiography; D004261:DNA Replication / Q000187:drug effects*; D008300:Maleic Hydrazide / Q000494:pharmacology*; D008741:Methyl Methanesulfonate / Q000494:pharmacology*; D009152:Mutagenicity Tests; D063245:Plant Development; D010944:Plants / Q000187:drug effects*; D013936:Thymidine / Q000378:metabolism; D014316:Tritium
D014316:Tritium; D008741:Methyl Methanesulfonate; D008300:Maleic Hydrazide; D013936:Thymidine