DNA laddering

[2] Separation of the fragments by agarose gel electrophoresis and subsequent visualization, for example by ethidium bromide staining, results in a characteristic "ladder" pattern.

A simple method of selective extraction of fragmented DNA from apoptotic cells without the presence of high molecular weight DNA sections, generating the laddering pattern, utilizes pretreatment of cells in ethanol.

This is due to DNA fragmentation taking place in a later stage of the apoptosis process.

[2] To enhance the accuracy in testing for apoptosis, other assays are used along with DNA laddering such as TEM and TUNEL.

[6] It is also important to note that DNA laddering occurs differently depending on the type of cell, so there may be slight changes in the process of DNA laddering depending on the cell that is being investigated.

White DNA bands against a dark grey background, resembling the rungs of a ladder — DNA laddering (left) visualised in an agarose gel by ethidium bromide staining. A 1 kb marker (middle) and control DNA (right) are included.