title: Unscheduled DNA synthesis in growing roots and stored embryos of Vicia faba after the action of maleic hydrazide and methyl methanesulphonate.
abstract: 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.
authors.affiliation: Institute of Molecular and Subcellular Biology, Comenius University, Bratislava, Czechoslovakia.
authors.forename: G
authors.initials: G
authors.lastname: Murín
mesh_terms: 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
chemical_list: D014316:Tritium; D008741:Methyl Methanesulfonate; D008300:Maleic Hydrazide; D013936:Thymidine