title: A comparison of DNA repair using the comet assay in tobacco seedlings after exposure to alkylating agents or ionizing radiation.
abstract: We employed single cell gel electrophoresis to analyze the kinetics of DNA repair in nuclei isolated from tobacco plants exposed to ethyl methanesulfonate (EMS), N-ethyl-N-nitrosourea (ENU) and gamma-radiation. DNA repair was measured as the reduction of the tail moment values as a function of time after the mutagen treatment ended. DNA damage in leaf nuclei of EMS-or ENU-treated tobacco plants persisted over a 72h recovery period. However, a reduction of the SCGE tail moment values in nuclei isolated from leaves was observed over a 4-week period of recovery. Newly emerged leaves expressed a lower level of DNA damage due to more efficient repair and/or dilution of initial DNA lesions during cell division. After 24h recovery, leaf nuclei from cells exposed to 20 or 40Gy of gamma-radiation expressed complete DNA repair. These data indicate that DNA lesions induced by alkylating agents are not readily repaired and persist beyond 4 weeks. Enzymes necessary to repair gamma-induced DNA lesions are fully functional in non-replicating leaf cells and single and double strand breaks are rapidly repaired.
authors.affiliation: Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Na Karlovce 1a, 160 00 6, Prague, Czech Republic.
authors.forename: T
authors.initials: T
authors.lastname: Gichner
authors.forename: O
authors.initials: O
authors.lastname: Ptácek
authors.forename: D A
authors.initials: DA
authors.lastname: Stavreva
authors.forename: E D
authors.initials: ED
authors.lastname: Wagner
authors.forename: M J
authors.initials: MJ
authors.lastname: Plewa
mesh_terms: D000477:Alkylating Agents / Q000633:toxicity*; D002467:Cell Nucleus; D020552:Comet Assay; D004247:DNA / Q000187:drug effects / Q000528:radiation effects; D004260:DNA Repair; D004586:Electrophoresis; D005020:Ethyl Methanesulfonate / Q000633:toxicity; D005038:Ethylnitrosourea / Q000633:toxicity; D005720:Gamma Rays; D009153:Mutagens / Q000633:toxicity*; D018515:Plant Leaves / Q000187:drug effects / Q000528:radiation effects; D018517:Plant Roots / Q000187:drug effects / Q000528:radiation effects; D010947:Plants, Toxic; D014026:Nicotiana / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects
chemical_list: D000477:Alkylating Agents; D009153:Mutagens; D004247:DNA; D005020:Ethyl Methanesulfonate; D005038:Ethylnitrosourea