Detection of unique or low copy number DNA sequences in complex genomes

The characterization of specific DNA sequences by means of hybridization techniques is of great relevance in the development of molecular biology. Because of its simplicity, the method described by Southern in 1975 (1) is widely used for such purposes. This method, also known as the Southern blot, is based on the hybridization of specific probes to DNA fragments immobilized onto a membrane filter after their separation by agarose gel electrophoresis. The identification of specific DNA fragments is possible since their relative positions are maintained during the transfer from the gel to the filter.