A rapid and simple method for labeling short DNA fragments using Taq polymerase.

This report describes a new method for labeling PCR-generated short length (60-120 bp) double-stranded DNA fragments for use as hybridization probes. The method utilizes gene-specific primers identical to those for PCR generation of non-radioactive DNA fragments. Radioactive probes are synthesized by Taq DNA polymerase without using PCR. Single-stranded (sense or antisense) and double-stranded probes can be individually prepared by selection of the appropriate primers. The labeling reaction reached maximum incorporation within 30 min with mean specific activities of 1.05 x 10(9) dpm/microgram (antisense single-stranded), and 1.62 x 10(9) dpm/microgram (double-stranded) were obtained using templates 69-117 of nucleotides. This method offers a simple and rapid means of generating antisense probes for Northern blot analyses and double-stranded probes for Southern blot analyses that provide highly intense signals with low background.