NUCLEIC-ACID DETECTION USING NONRADIOACTIVE LABELING METHODS

Nucleic acid probe-based assays are now widely used in genetic researc h, human identification, forensics and in a broad spectrum of clinical assays in the fields of microbiology, haematology/oncology and virolo gy. Labelled probes are used in a variety of assay formats including d ot-blots, Southern blots (DNA target), Northern blots (RNA target), We stern blots (protein target), in situ hybridization, plaque or colony screening and immobilized arrays on silicon or glass surfaces. Traditi onally, the probes used in these assays have a radioactive (32)phospho rous label that has a short shelf-life, is dangerous, has high disposa l costs and, when labelled to high specific-activity, may be unstable. Extensive efforts to develop alternative labelling techniques have re sulted in colorimetric, chemiluminescent and fluorescent assay formats . This review summarizes the properties desired in a probe, describes the advantages and disadvantages of the different nonradioactive label ling strategies, and illustrates examples of probe-based assays in whi ch detection is facilitated by imaging samples using a general purpose fluorescence scanner.