title: G2 effects of DNA-repair inhibitors on chromatid-type aberrations in root-tip cells treated with maleic hydrazide and mitomycin C.
abstract: In recent years the existence of a DNA-repair process in G2 has been proposed to explain the potentiating effects of DNA-repair inhibitors given in G2 on chromatid aberrations (CA) induced by S-dependent as well as S-independent DNA-damaging agents. In the present report, root-tip cells of Allium cepa were exposed to maleic hydrazide (MH) or mitomycin C (MMC) and post-treated in G2 with caffeine (Caff) and various inhibitors of DNA synthesis. No enhancement of chromosome damage was observed when Caff was present in G2, but hydroxyurea (HU) or 5-fluorodeoxyuridine (FdUrd) potentiated the frequencies of CA. A slight additional increase of CA frequencies was observed following treatment with Ara C and excess thymidine in G2. When MH-damaged cells were pulse-treated with Caff earlier during recovery, the yield of CA was enhanced. The earlier Caff was present following MH treatment, the stronger was the potentiation.
authors.affiliation: Departamento de Biologia Celular, Facultad de Biologia, Sevilla, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Mateos
authors.forename: J
authors.initials: J
authors.lastname: Piñero
authors.forename: T
authors.initials: T
authors.lastname: Ortiz
authors.forename: F
authors.initials: F
authors.lastname: Cortés
mesh_terms: D002110:Caffeine / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects; D002869:Chromosome Aberrations; D002875:Chromosomes / Q000187:drug effects; D003561:Cytarabine / Q000633:toxicity; D004249:DNA Damage; D004260:DNA Repair / Q000187:drug effects*; D005467:Floxuridine / Q000633:toxicity; D006918:Hydroxyurea / Q000633:toxicity; D066298:In Vitro Techniques; D007399:Interphase; D008300:Maleic Hydrazide / Q000494:pharmacology*; D016685:Mitomycin; D008937:Mitomycins / Q000494:pharmacology*; D010944:Plants; D011724:Pyridazines / Q000494:pharmacology*; D013936:Thymidine / Q000633:toxicity
chemical_list: D008937:Mitomycins; D011724:Pyridazines; D005467:Floxuridine; D003561:Cytarabine; D002110:Caffeine; D016685:Mitomycin; D008300:Maleic Hydrazide; D013936:Thymidine; D006918:Hydroxyurea