What is Southern Blotting?


Southern blotting is a technique that allows researchers to detect and identify specific DNA sequences from a complex mixture of DNA samples. It is based on the principle of transferring DNA fragments that have been separated by gel electrophoresis to a carrier membrane, such as nitrocellulose or nylon, and then hybridizing them with a complementary probe that is labeled for detection. The probe can be radioactive, fluorescent, or chromogenic, depending on the method of visualization. Southern blotting can be used for various purposes, such as gene mapping, gene expression analysis, DNA fingerprinting, diagnosis of genetic diseases, and forensic investigations.

The technique was named after its inventor, Edwin M. Southern, a molecular biologist who developed it in 1975 while working at the University of Edinburgh. He published his first paper on the method in the Journal of Molecular Biology in 1975, titled "Detection of specific sequences among DNA fragments separated by gel electrophoresis". The technique was soon adopted by other researchers and became a widely used tool in molecular biology. In recognition of his contribution, Southern was awarded the Lasker Award in 2005 and the Royal Medal in 2012. The term "Southern blotting" has also inspired the names of other similar techniques that use RNA or protein as the target molecule, such as Northern blotting and Western blotting.