The main difference between Southern Blot and Western Blot is that Southern Blot is a technique used to detect a specific DNA fragment in a given sample, while Western Blot is used to find a specific protein in a given sample.

Southern Transfer vs. Western Transfer

Blotting is a standard technique that scientists use to separate different molecules from a mixture or sample. In this technique, macromolecules such as nucleic acids (DNA and RNA) and proteins in a mixture are moved through a gel plate. Here, tiny particles will move faster than larger ones. These molecules are pressed against the surface of an immobilized membrane which transfers the molecules to the membrane. There are different types of blot based on the detection of specific material, i.e. southern blot, northern blot, and western blot. Southern blot is the type of blot used to detect DNA, while Western blot it is used to discover proteins. The southern transfer was developed by Edward M. Southern in 1975. Hence, it is known as southern transfer. On the other hand, the Western Blot was developed by George Stark’s group at Stanford University in 1979. This name was used to coincide with the Southern Blot. Southern blotting is used to find a specific DNA sequence, while Western blotting is used to find a specific protein or amino acid sequence.

Comparative chart

The southern transfer is the oldest method of transfer that was given by Edwin Southern, thus called the southern transfer. It is used to discover a specific DNA sequence in a given sample or mixture. The steps involved during Southern blotting are electrophoresis, blotting, and detection of specific sequences. First, DNA is fragmented with the help of a specific restriction enzyme. Then the desired DNA fragments are separated by gel electrophoresis. These fragments are denatured with the help of an alkaline solution, for example NaOH, etc. to separate the two strands of DNA. These single-stranded DNA fragments are then transferred to a membrane through the transfer process. This membrane bound DNA is then treated with a labeled probe. This probe will adhere to its complementary strand in membrane DNA which can be visualized by autoradiogram, etc.

What is Western Blot ?

The Western blot method was invented by George Stark’s group at Stanford University that is used to identify a specific amino acid sequence in protein. Also known as protein blot or immunoblot. The steps during Western blotting are electrophoresis, blotting, and detection of specific proteins. First, homogenize the mixture. Then separate the molecule of interest with the help of electrophoresis. Transfer these molecules onto the membrane and identify the specific protein using a specific probe.

Key differences

1. A technique that is used to find a specific DNA sequence in a given mixture is known as a Southern blot, while a technique that is used to find a specific amino acid sequence of the protein in a given mixture is known as a Southern blot.
2. The Southern Blot was developed by Edward M. Southern in 1975, known as the Southern Blot. On the other hand, the western blot was developed by George Stark’s group at Stanford University in 1979.
3. Southern blotting is used to discover a specific DNA sequence. Rather, Western blotting is used to discover a specific protein or amino acid sequence.
4. The southern transfer works on the principle of hybridization on the other hand; Western blot works on the principle of immunodetection method or antigen-antibody interaction.
5. A single stranded DNA or sometimes RNA is used as a probe in the Southern blot on the other side, in the Western blot primary and secondary antibodies are used as the probe.
6. Agarose gel electrophoresis is used in the Southern blot, while the SDS PAGE / polyacrylamide gel is used to separate proteins in the Western blot.
7. Southern blotting follows the capillary blot procedure, on the other hand; Western Blotting follows the electrical blotting procedure.
8. During Southern blotting, the sample must be denatured, while during Western blotting, the sample must be in its original state.
9. On the other hand, no step like blocking is involved in the Southern Blot; During Western Blot, non-specific antibody sites are blocked on nitrocellulose paper with the help of powdered milk or bovine serum albumin (BSA).
10. The common labeling methods used in southern blotting are the use of chromogenic dyes or radioactive labeling or fluorescent labeling, etc., while the labeling methods used in Western blotting are the use of fluorescently labeled antibodies or labeling. radioactive, chromogenic dyes or diaminobenzidine formation, etc.
11. Light detection, autoradiography and color changes are used as detection methods in the southern transfer, while the detection methods in western transfer are color changes and light detection, etc.
12. The Southern blot is used in DNA detection, paternity tests, DNA fingerprints, for victim identification, to identify criminals, to find infectious agents, and to identify gene mutations or rearrangements, etc. Rather, Western Blot is used to find the amount of protein in a mixture, to detect the presence of HIV, viruses and bacteria, etc. in the serum, to find faulty proteins, and to be used as a definitive measure for herpes, hepatitis B, Lyme disease and Creutzfeldt-Jacob disease, etc.

The discussion above summarizes that southern blotting is the oldest blotting technique used to find a specific DNA segment in a sample, while Western blotting was later discovered and used to identify a specific amino acid sequence or a specific protein.