CARCINOGEN-INDUCED MITOCHONDRIAL-DNA DAMAGE IN THE IN OVO MODEL

After experimental exposure of turkey eggs in an in ovo model, the ind uction of preneoplastic liver lesions (Enzmann el nl., 1992 and 1995a) and alterations of the mitochondrial (mt) DNA of embryonic turkey liv ers (Enzmann er al., 1995b) could be demonstrated, showing the sensiti vity and usefulness of this short-termed and inexpensive system for ca rcinogenicity testing. Chemically induced modification of mtDNA may be an important indicator of the carcinogenic potential of substances, a s the mt genome may display a higher sensitivity to DNA damaging effec ts compared to nuclear DNA. To characterize mtDNA damages in ovo, appl ication of diethylnitrosamine (DEN) was performed onto the chorioallan toic membrane (CAM) of the avian embryo. First, the distribution of a model substance after CAM application was measured by autoradiography. MtDNA damage after DEN exposure was demonstrated by gel electrophores is of isolated mtDNA. Nitrosamine treatment induced a dose-dependent c hange of mtDNA conformation from supercoiled to relaxed shape, pointin g to a possible induction of single-strand breaks. (C) 1998 Elsevier S cience Ltd. All rights reserved.