Comet assay limitations

To this end, the authors perform a second comet assay. Only limited results, however, are shared PM2 5 from only one city (Baton Rouge) was tested using only one cell line (K562 myeloid leukemia cells), thereby following a broad-to-narrow approach. The results are presented in excerpt 4E. As shown in Eigure 3 (excerpt 4E), cells were exposed to (A) a blank extract, (B) a PM2 5 extract, (C, D, E) a PM2 5 extract mixed with one of three different free radical scavengers, (E) a positive control, and (G, El) a PM2 5 extract mixed with one of two different metal-ion chelators. The free radical scavengers remove free radicals the... 

Collins, A.R. (2004). The comet assay for DNA damage and repair. Principles, applications and limitations. Molecular Biotechnology, 26,249-261. 

Delincee, H., Khan, A.A., and Cerda, H., Some limitations of the comet assay to detect the treatment of seeds with ionising radiation, Eur. Food Res. Technol, 216, 343, 2003. 

DNA repair can be detected by the same assays (alkaline elution and Comet) that are used to detect DNA damage, but with various time intervals between the end of exposure and the time of sampling. An additional assay for assessing DNA repair has been utilized for many years, namely the unscheduled DNA synthesis (UDS) assay. The endpoint measured is the uptake of tritiated thymidine into DNA repair sites following exposure. The sensitivity of the assay is relatively low, especially in vivo, and this limits its predictive value for hazard identification. Thus, a negative response in a UDS assay has very limited value because of this low sensitivity. 

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