COMPARISON OF SPECTROMETRIC AND AUTOPHOTOGRAPHIC METHODS FOR DETERMINING DNA CONCENTRATIONS

Earlier studies from this laboratory demonstrated that a lumigenic det ection method could utilize liquid scintillation counters for quantita tion of DNA. Advantages included: 1) elimination of the need for radio active probes, 2) rapid localization of spots by exposure of X-ray fil m and 3) longer shelf life of probe DNA. A major disadvantage of cutti ng spots from the membrane for luminometric assay is the destruction ( or consumption) of the membrane; another disadvantage is the length of time spent handling the membrane while trying to cut out individual s pots. When transmittance was compared with counts per minute for targe t CAT DNA, both methods gave statistically significant differences bet ween 10 and 100 picograms of target DNA but less than 10 picograms wer e not significantly distinguished by either method. The digitized x-ra y films read by image analysis allowed reliable determination of targe t DNA concentrations and leaves the original membrane intact to serve as a permanent record of experiments. (C) 1994 Academic Press, Inc.