Visualization of cellular DNA crosslinks by atomic force microscopy.
Cellular DNA crosslinks are a type of DNA damage induced by toxic chemicals or high-energy radiation. If damaged DNA is not rapidly repaired, cells will die or mutate. To evaluate the types of DNA damage and their influence on vital cell activities, it is necessary to be able to detect DNA crosslinks. To date, indirect methods such as alkaline elution, potassium chloride-sodium dodecyl sulfate assay and comet assay have been used to detect DNA damage. Direct morphological observation, on the other hand, may be a useful tool to differentiate the types of DNA damage. In this report, atomic force microscopy (AFM) has been employed to visualize the breakage and crosslinking of cellular DNA strands in cells treated with formaldehyde and hydrogen peroxide. Our results showed that toxic chemical-induced crosslinking of cellular DNA occurred in a dose-dependent manner. DNA conglomerates were observed with high concentrations of formaldehyde, and the AFM observations were consistent with those of a comet assay. Our experiments demonstrate that AFM is an efficient method to differentiate the types of DNA damage. SCANNING 31: 75-82, 2009. (c) 2009 Wiley Periodicals, Inc.
Zhang
Kun
K
Institute of Photonics and Photon-Technology, Northwest University, Xi'an, People's Republic of China.
Qi
Hao
H
Li
Hao
H
Liu
Ying
Y
Chen
Wenfang
W
D020552:Comet Assay; D004247:DNA / Q000032:analysis* / Q000737:chemistry / Q000187:drug effects; D004249:DNA Damage; D005557:Formaldehyde / Q000737:chemistry; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D020014:K562 Cells; D018625:Microscopy, Atomic Force / Q000379:methods*; D016877:Oxidants
D016877:Oxidants; D005557:Formaldehyde; D004247:DNA; D006861:Hydrogen Peroxide