Adaptation to alkylation damage in DNA measured by the comet assay.
The alkylating mutagens N-methyl-N-nitrosourea (MNU) and methyl methanesulfonate (MMS) were studied for their potential to induce DNA strand breaks and abasic (AP) sites in meristematic nuclei of Vicia faba root tips by the comet assay. The alkaline unwinding/neutral electrophoresis (A/N) and alkaline unwinding/alkaline electrophoresis (A/A) protocols were used for detection of DNA damage. With the A/N comet assay, less DNA damage was seen after conditioning pretreatment with a low dose prior to a high challenging dose of alkylating mutagens as compared to application of the high dose only, whereas a nearly additive effect was seen when the A/A comet assay was used. Adaptation was even more obvious when AP sites were revealed by the AP-endonuclease activity of exonuclease III. The adaptation observed with the A/N comet assay was abolished by pretreatment with the protein synthesis inhibitor cycloheximide. These data suggest that the comet assay is able to detect on molecular level a phenomenon resembling clastogenic adaptation.
Angelis
K J
KJ
Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Praha, Czech Republic. angelis@ueb.cas.cz
McGuffie
M
M
Menke
M
M
Schubert
I
I
D000222:Adaptation, Physiological; D000477:Alkylating Agents / Q000633:toxicity*; D002453:Cell Cycle / Q000187:drug effects; D020552:Comet Assay; D004249:DNA Damage / Q000187:drug effects*; D007887:Fabaceae / Q000166:cytology / Q000187:drug effects / Q000235:genetics; D008698:Mesylates / Q000633:toxicity; D008770:Methylnitrosourea / Q000633:toxicity; D018517:Plant Roots / Q000187:drug effects; D010946:Plants, Medicinal; D014176:Protein Biosynthesis; D011506:Proteins / Q000187:drug effects
D000477:Alkylating Agents; D008698:Mesylates; D011506:Proteins; C045880:methanesulfonic acid; D008770:Methylnitrosourea