A widely used cytochemical technique for evaluation of DNA damage associated with apoptosis is the terminal deoxynucleotidyl transferase-mediated in situ end labeling or TUNEL assay. However the TUNEL assay has its drawbacks in that false positive staining makes the assay unreliable as a marker for apoptosis (see figure 1) 1-5. A more universal and specific marker for apoptosis is the morphological changes in nuclei that reflect chromatin condensation in to compact masses 6-7
Further biochemical and cytochemical studies have demonstrated the increased susceptibility of apoptotic DNA to thermal denaturation. Analysis of nuclei by scanning calorimetry to detect thermal induced DNA denaturation and analysis of DNA fragmentation by electrophoresis have shown that intact apoptotic DNA is susceptible to denaturation at lower temperatures then that of non-apoptotic cells 8
- Much more Reliable as compared to TUNEL assays – No False positive signals.
- Readout – Flow cytometry, 96 well plate reader, Fluorescence microscope.
- Yields both quantitative and qualitative results. Gives a strong positive signal.
- Ease Of Use: Results in less than 60 minutes.
- No need to run DNA ladder assays to detect DNA damage in cells.