UVB DNA DOSIMETERS ANALYZED BY POLYMERASE CHAIN-REACTIONS

Purified bacteriophage lambda DNA was dried on a UV-transparent polyme r film and served as a UVB dosimeter for personal and ecological appli cations. Bacteriophage lambda DNA was chosen because it is commerciall y available and inexpensive, and its entire sequence is known, Each do simeter contained two sets of DNA sandwiched between UV-transparent po lymer films, one exposed to solar radiation (experimental) and another protected from UV radiation by black paper (control), The DNA dosimet er was then analyzed by a polymerase chain reaction (PCR) that amplifi es a 500 base pair specific region of lambda DNA. Photoinduced damage in DNA blocks polymerase from synthesizing a new strand; therefore, th e amount of amplified product in UV-exposed DNA was reduced from that found in control DNA, The average lesion frequency per 500 base pair p er strand at 16 PCR cycles was similar to 1,22, 1.00, 0.70 and 0.50 fo r 30 ng, 50 ng, 100 ng and 150 ng of dried DNA, respectively, after a total dose of 60 kJ m(-2) delivered with a solar UVB simulator, Althou gh the average lesion frequency increases linearly with increasing dos es for four different amounts of template DNA, the lesion frequency se ems to be averaged by the amplified products from the protected lambda DNA molecules below the top few layers. The average daily dose, equiv alent to the UV dose applied with the solar WE simulator, was 10.2 +/- 0.4 kJ m(-2) with the 50 ng containing DNA dosimeter in September 199 5 in Melbourne, FL, Both 50 ng and 150 ng containing DNA dosimeters pr oduced the same average daily dose within experimental error in Januar y 1996, which was 5.2 +/- 0.3 kJ m(-2) at the same location, The dried lambda DNA dosimeter is compact, robust, safe and transportable, stab le over long storage times and provides the total UVB dose integrated over the exposure time.