Oligonucleotides are a convenient alternative to conventional, cloned DNA probes since they can be rapidly synthesized in large quantities relatively cheaply. They can be made to very specific regions of the genome, without reference to restriction enzyme sites, and are therefore of particular value in the analysis of gene families where sequences may be highly conserved. Oligonucleotides are stable, do not self-anneal, and generally cause fewer problems with nonspecific binding. They are amenable to several labeling techniques, both radioactive and nonradioactive; such methods include chemical modification during synthesis and the enzymatic incorporation of labeled nucleotides at the 5′ end or the 3′ end.
