Since DNA degradation to oligonucleosomes is not essential for apoptosis and all cells must undergo DNA degradation to produce the large fragments (12), high molecular weight (HMW) DNA fragmentation has been considered a more reliable biochemical marker for apoptosis. When internucleosomal DNA cannot be demonstrated in some cells, there is considerable HMW
DNA fragmentation, producing fragments of 50-300 kb that can be identified by pulse-field gel electrophoresis.
Pulse-field gel electrophoresis is a specialized technique for resolving DNA molecules in the range of kilo- to mega-bases (Mb). By alternating the electric field between spatially distinct pairs of electrodes, HMW DNA fragments and chromosome-size DNA from 200 to over 12000 kb can be separated because they are able to reorient and move differentially through the pores of an agarose gel.
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