Hybridization and Competition Hybridization of Southern Blots

This chapter describes the detection of specific DNA sequences by hybridization to a labeled probe of complementary sequence. This method is suitable for the detection of a wide range of DNA concentrations down to single-copy genes within mammalian genomic DNA (little more than 1 pg of hybridizing DNA in a total of 10 �g). In principle, hybridization consists of the annealing of a single-stranded, labeled nucleic acid probe to denatured DNA fixed to the filter. In practice, this method is designed to provide a balance between maximizing the specific signal and minimizing the nonspecific background.