Southern Blot- Definition, Principle, Steps, Results, Applications


Southern blotting is a molecular biology technique that allows the detection and quantification of specific DNA sequences in complex DNA samples. The technique involves the transfer of DNA fragments that are separated by electrophoresis onto a membrane, where they are immobilized and hybridized with a labeled probe that recognizes the target sequence. The probe can be detected by various methods, such as radioactivity, fluorescence, or chemiluminescence, depending on the type of label used. Southern blotting can be used for various applications, such as gene discovery, mapping, evolution, and diagnosis.

The technique was named after its inventor, Edwin Southern, a British biologist who developed it at Edinburgh University in the 1970s. He first published the method in 1975, after combining three innovations: the use of restriction enzymes to cut DNA at specific sequences, the use of gel electrophoresis to separate DNA fragments by size, and the use of blotting methods to transfer RNA molecules to a membrane. He later modified the technique to transfer DNA molecules instead of RNA. The technique was widely adopted by other researchers and gave rise to other blotting methods that use RNA (northern blotting) or protein (western blotting) as targets.