DAMAGE TO MITOCHONDRIAL-DNA INDUCED BY THE HEPATOCARCINOGEN DIETHYLNITROSAMINE IN OVO

Different doses of the hepatocarcinogen diethylnitrosamine (DEN) were injected into fertilized turkey eggs 8 days before hatching. The embry os were removed from the eggs after 4 days and liver samples were shoc k frozen. Mitochondrial DNA (mtDNA) was purified from the samples. Ele ctrophoresis on agarose gels with native mitochondrial DNA and with ri bonuclease-treated mitochondrial DNA revealed a DEN-induced effect on the molecular size of the mtDNA. The content of mtDNA of the regular s ize of 16 kb dose-dependently decreased, whereas the amount of mtDNA f ragments of various size increased. Fluorescent staining of the electr ophoresis gels allowed the densitometric quantification of the mitocho ndrial DNA of the regular band at 16 kb and the amount of fragments of irregular size (smear). The diethylnitrosamine-induced effect was dos e-dependent over the whole dose range from 1.24 to 6.2 mmol/kg. Even t he lowest dose (10 mg DEN per egg) showed clear-cut effects. Mitochond rial damage and malfunction may be mechanistically involved in the neo plastic transformation and in aging phenomena. The in ovo model is a s imple and rapid approach for investigations on chemically induced alte rations of mtDNA.