ABSTRACT
Double-stranded DNA denatures into single strands as the temperature rises but renatures into a double-stranded structure as the temperature falls. Any two single-stranded nucleic acid molecules can form double-stranded structures provided that they have sufficient complementary nucleotide sequence to make the resulting hybrid stable under the reaction conditions. The concentration of a specific nucleic acid sequence in a sample can be measured by hybridization with a suitable labeled DNA probe. After hybridization, nuclease is used to destroy unhybridized probe and the probe remaining is a measure of the concentration of the target sequence. For in situ hybridization, a tissue sample is incubated with a labeled nucleic acid probe, excess probe is washed away and the location of hybridized probe is examined. DNA microarray is a large number of DNA fragments or oligonucleotides arrayed in known positions on a glass slide. After hybridization with fluorescently-labeled target cDNA, examination using automated scanning laser microscopy indicates which DNA sequences are expressed.
