Southern blotting is a technique used in genetic science to determine the presence of a single specific gene within a genome. This technique was developed first by Edward M Southern, and is hence named after him. While the process itself can be complicated, the objective of Southern blotting itself is pretty simple – transferring DNA from a gel, usually an agarose gel, to a membrane to locate a specific gene. The entire blotting process can be broken down to four effective steps. The first step is to digest the DNA using some suitable enzymes, often called restrictive enzymes. The next step is to separate the digested DNA using the process of electrophoresis. This is done by placing the gel in the above-mentioned gel. The separation involves sorting out double strands of DNA into single strands. Larger fragments of DNA can be made smaller by treating it with HCl (required amounts and concentration), in a process referred to as depurination. If this step is done, the gel's acidic content has to be neutralized before you can move to the next step. Even otherwise, the neutralization is required. This is because separation of the strands involves treatment with sodium hydroxide, which is a basic solution (the basic quality of the solution has to be neutralized before the next step). Once the DNA has been neutralized, it is transferred to a membrane. Once on the membrane, the DNA is treated with UV radiation. This is the Southern blotting technique.
