Abstract
Single-stranded nucleic acids can form stable duplexes if they encounter complementary sequences under appropriate conditions. This reaction is called hybridization and has been extensively used during the past 15 years to explore the structure and expression of cellular and viral genes. Particularly with the advance of molecular cloning, hybridization with specific probes has made it possible to isolate and study individual genes from genomic libraries and has thus contributed significantly to our understanding of eukaryotic gene organization.