dideoxynucleic acids as the dideoxynucleic acid in a given reaction is present at a low concentration relative to its comparable deoxynucleic acid it is not used at every occurrence in the sequence the result is a series of extension products of various lengths depending upon the location at which the dideoxynucleic acid was incorporated by also incorporating a detection system of some type typically radioactive or fluorescent it is possible to determine the sequence of nucleic acids in the region in question genomic dna was isolated from peripheral blood mononuclear cells by the high salt extraction method of miller et al a simple salting out procedure for extracting dna from human nucleated cells nucleic acids res 1988 16 3 p 1215 and resuspended in sterile water to a concentration of 1 u03bcg u03bcl the pcr primer hd17 f3 5 39 ggc gca cct gga aaa gc 3 39 purchased from operon technologies inc of alameda calif seq i d no 1 was 5 39 end labeled with fluorescein by the incorporation of a fluorescein amidite during hd17 f3 synthesis by operon technologies amplification of hd specific sequence was completed using primers hd17 f3 and hd17 r1 5 39 gcg gct gag gaa gct ga 3 39 operon technologies seq id no 2 obtained as hplc purified stocks each pcr reaction contained the following 100 500 ng of genomic dna pcr buffer iomm tris ph 8 4 5 omm kcl 2 mm mgcl 2 obtained from sigma chemical of st louis mo dntp 39 s pharmacia to a final concentration of 200 u03bcm 50 of the dgtp content was 7 deaza gtp pharmacia 12 5pm hd17 r1 3 1 pm hd17 f3 9 4 pm fluorescein labelled hd17 f3 2.