DETECTION OF C8-2-AMINO-1-METHYL-6-PHENYLIMIDAZO[4,5-B]PYRIDINE ADDUCT AS A SINGLE SPOT ON THIN-LAYER CHROMATOGRAPHY BY MODIFICATION OF THEP-32 POSTLABELING METHOD

l)-2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (dG-C8-PhIP) has be en shown to be a major adduct in DNA of rats given [H-3]PhIP. However, when DNA from organs of rats fed PhIP was analyzed by the P-32-postla beling method under standard and adduct-intensification conditions, fo ur adduct spots were observed, and 3',5'-pdGp-C8-PhIP was detected as a minor, not a major, adduct spot. Since the three other major adduct spots were suspected to be those of adducted di- or oligo-nucleotides, the P-32-labeled samples were further treated with nuclease P1 and ph osphodiesterase I and found to yield only a single adduct spot. The ma terial in this adduct spot was confirmed to be 5'-pdG-CS-PhIP. Thus, u sing this newly modified P-32-postlabeling method, dG-C8-PhIP was dete cted as a major adduct in DNA of rats given PhIP.