Principle of Southern blotting: In this technique, DNA is usually converted into conveniently sized fragments by restriction digestion. The fragments are then separated by migration through an agarose gel, and transferred to a nylon or nitrocellulose membrane by capillary action. The DNA of interest can be identified by hybridization to radioactive or chemiluminescent probes and visualized by autoradiography or staining.
Application of Southern blotting:
• Southern blots can easily provide a physical map of restriction sites within a gene located normally on a chromosomes.
• Southern blots reveal the number of copies of the gene in a genome.
• The degree of similarity of the gene when compared with other complementary genes. Western blotting is the technique for protein identification.