Fluorescence line-narrowing spectrometry: A versatile tool for the study of chemically initiated carcinogenesis

An important initiating step in the induction of tumors is believed to be the covalent binding of an active carcinogenic species to a cellular macromolecule, e.g. DNA. Therefore, a spectroscopic technique which allows for positive identification of the intact (macromolecular) DNA adduct and/or isolated damaged nucleosides/nucleotides is highly desirable. It is shown that fluorescence line-narrowing spectroscopy (FLNS) is a rapid, versatile, highly sensitive and selective analytical technique, which can be used directly to characterize DNA adducts and isolated nucleosides. FLNS possesses sufficient resolution to distinguish between the major DNA adducts derived from different enantiomers of benzo[a]pyrene diol-epoxide (BPDE). With the present limit of detection (∼1 adducted base per 10⁸ normal base pairs for 100 μg of DNA), the technique is applicable to in vivo samples. Analysis of liver DNA from fish exposed to benzo[a]pyrene (BP) (100 mg BP/kg fish) showed that a major DNA adduct is derived from syn-BPDE.