OBJECTIVESTwo assay methods, namely the neutral Comet assay andterminal desoxynucleotidyl transferase (TdT) assay, were carried out for comparison to investigate the capability of using the neutral Comet assay as an alternative for detection of apoptosis.

MATERIALS AND METHODSChinese hamster ovary-K1 (CHO-K1) cells were exposed to gamma-rays with different doses and then the frequencies of apoptotic cells were determined at given points of time using the neutral Comet assay andTdT assay.

RESULTSApoptotic frequency of CHO-K1 cells after gamma-irradiation is dependent on both time after irradiation and radiation dose using either the neutral Comet assay orTdT assay. There are differences between the data obtained using the neutral Comet assay andTdT assay (p<0.01, Student's t-test).

CONCLUSIONSThe neutral Comet assay appears to be an appropriate tool for detection of radiationinduced apoptosis at the early stage of the process. Compared to the other methods such as theTdT assay, the neutral Comet assay is a rapid, simple and economical method for detection of apoptosis.