ELIMINATION OF FALSE POSITIVES GENERATED THROUGH PCR REAMPLIFICATION OF DIFFERENTIAL DISPLAY CDNA

Differential display (DD) is a powerful molecular tool that allows the identification and subsequent isolation of transcripts differentially expressed between biological samples, for example, between undifferen tiated and differentiated cells, between different tissues or in one t issue at different stages of development. However significantly high r ates of apparent false positives have been reported using this techniq ue. We suggest that the vast majority of false positives do not repres ent the originally selected transcript, but instead result from the re -amplification of cDNA species that co-migrate with the cDNA of intere st in DD gels. Here we describe the use of a procedure to resolve co-m igrating cDNAs and to purify the candidate of interest before cloning. The use of this modified technique resolves downstream problems encou ntered during DD experiments.