Southern blotting

Although largely replaced by PCR-based methods, Southern
blotting is still necessary to detect relatively large changes in
the DNA that exceed the limits of PCR. Genomic DNA is first
cut using restriction enzymes and the digested fragments
fractionated using gel electrophoresis. The DNA is then
transferred by capillary blotting onto nylon membrane before
radiolabelled probes are used to investigate the region of
interest.