Southern blot

The first one is the restriction endonucleases, which were developed at Johns Hopkins University by Tom Kelly and Hamilton Smith.

The second innovation is the gel electrophoresis that is based on separation of mixtures of DNA, RNA, or proteins according to molecular size, which was also developed at Johns Hopkins University, by Daniel Nathans and Kathleen Danna in 1971.

The third innovation is the blotting-through method which was developed by Frederick Sanger, when he transferred RNA molecules to DEAE paper.

[7] After the DNA fragments are immobilized on the membrane, prehybridization methods are used to reduce non-specific probe binding.

It also allows for the fixation of the target-probe hybrids, required for analysis by autoradiography or other detection methods.

A probe that hybridizes only to a single DNA segment that has not been cut by the restriction enzyme will produce a single band on a Southern blot, whereas multiple bands will likely be observed when the probe hybridizes to several highly similar sequences (e.g., those that may be the result of sequence duplication).