Detection of Gamma Radiation-Induced Oxidation in Animal and Bacterial DNA

The choice to examine DNA seems obvious, since DNA is a sensitive cellular target to irradiation and the changes in DNA are responsible for many effects observed in irradiated foods, such as the inactivation of microorganisms, elimination of insects, inhibition of sprouting in bulbs and tubers and delay of ripening in several fruits1. Therefore, these changes in DNA should be discernible in microbial or insect DNA or in the nucleic acids in the food itself. If DNA changes were specific to irradiation, a detection method could be designed that would have wide applicability, since most foods are derived from living organisms and obviously they contain DNA. Such a method could almost be the universal method for detecting the radiation treatment of foods. Radiation-induced changes in DNA can be analysed by a variety of analytical techniques1-2 that have mostly been employed on pure DNA or on DNA in living cells in radiation biology research. Whether or not some of these techniques can be utilized to detect irradiated food, has recently been very briefly discussed3-5. In oxic cells, the contribution of free radicals to the lethal action and DNA damage by ionising radiation amounts to around 70%6-7. Hydroxyl radical produces a number of lesions in DNA and nucleoprotein such as base lesions, sugar lesions, single-strand breaks, double-strand breaks, abasic sites and DNA-protein cross-links by a variety of mechanisms4-5. Gamma radiation generates a lot of base products such as Fapy Guanine, 8-OHdG, 2-hydroxyadenine, 5-hydroxy cytosine, 5,6-dihydroxycytosine, 5-hydroxy uracil etc.5.