Primed in Situ Labeling as a Fast and Sensitive Method for the Detection of Specific DNA Sequences in Chromosomes and...

Primed in situ labeling (PRINS) has become a routine technique for the microscopical staining of specific DNA sequences in cells and nuclei. For this purpose, the technique has the general advantage of being fast, simple, and sensitive. Furthermore, the reaction characteristics of the technique enable it to discriminate efficiently among closely related sequences-sometimes even when these differ by only one base. This high selectivity is obtained partly because the technique works optimally with oligonucleotide probes, which select more efficiently among closely related sequences than cloned probes do. This selectivity is further enhanced because no labeling occurs subsequent to probe binding unless the hybridized probe can function as primer for DNA synthesis, a process that is efficient only when the probe (primer) matches the target perfectly. Should this in itself provide insufficient selectivity, the involved chain elongation of the probe can be used in various ways to increase the selectivity of the staining further. These features of the technique have made it attractive for the detection of repeated DNA sequences, which now can be detected with a one-step procedure of a few minutes' duration, and make it a good candidate for the future detection of single-base variations in single-copy sequences in situ.