SUBTRACTIVE CLONING - PAST, PRESENT, AND FUTURE

Subtractive cloning is a powerful technique for isolating genes expres sed or present in one cell population but not in another. This method and a related one termed positive selection have their origins in nucl eic acid reassociation techniques. We discuss the history of subtracti ve techniques, and fundamental information about the nucleic acid comp osition of cells that came out of reassociation analyses. We then expl ore current techniques for subtractive cloning and positive selection, discussing the merits of each. These techniques include cDNA library- based techniques and PCR-based techniques. Finally, we briefly discuss the future of subtractive cloning and new approaches that may augment or supersede current methods.