Southern blotting is a technique of biotechnology which is used to determine and isolate the particular gene or DNA sample present in the genome.

Edward M. Southern was the scientist who developed the technique of southern blotting in 1970. Usually molecular biology makes use of this technique to isolate the particular fragment of DNA from the reaction mixture. Scientists use the method of gel electrophoresis for the identification of DNA sample and then the sequences of the sample DNA molecule can be determined by probe hybridization.

Process of Southern Blotting:-

Following are the steps involved in the process of Southern blotting:

1) A sample of DNA molecule is taken which is extracted from the cells. This DNA is cut into small fragments with the restriction enzymes.

2) The cut pieces of DNA are placed in the agarose gel through which electric current is passed. This way the DNA fragments convert into single strands and they are also separated according to their size.

3) When the DNA strands are separated according to their size, then they are placed on a nylon sheet. They stay immobile on the sheet. The sheet is then incubated.

4) Then the sequences of the single DNA strand on the membrane are exposed which is the target DNA.

5) When the sequences of the target DNA probe are determined then it is labeled so that it can be identified. The tagging is done by a fluorescent material so that it can be distinguished.

6) When the probe is labeled, now it can be taken out of the nylon membrane. Now they can be viewed through autoradiography on the x-ray film.

Uses of southern Blotting:-

The most common use of southern blotting is to get the sample of DNA which has to be used for other purposes. If the number of similar and desired DNA probes have to be found in a process then also southern blotting is used. The most important use of this technique is to determine that either the foreign DNA has transferred into the bacterial cell or not. Genetic manipulation can be determined with this technique.

Applications of Southern Blotting:-

Detection of Mutations:-
The method of Southern blotting along with the technique Restriction length Fragment Polymorphisms is used to map the genes of an individual. Both of these techniques together map the chromosomes and detect a particular mutation in the genome. Mutations like insertion and deletion can easily be detected with this technique. The genetic diseases can easily be detected with this technique.

DNA Fingerprinting:-
The technique of southern blotting is also useful in the process of DNA fingerprinting. The evidence which is collected from the crime scene is observed with this technique and the sample of DNA probes are matched with the person's DNA. The sample may be fresh or old and may be in the form of saliva, urine, hair or nails.

As it is known that southern blotting determines all the sequences of the sample of DNA or RNA, so if the sequences of amino acid sequences of a particular protein are known then it is easy to clone another protein from the existing one.

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