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Transplacental DNA Adduct Formation by Dibenzo[a,l]pyrene in Mice Daniel J. Albershardt Senior, Dept. of Biochemistry/Biophysics Dr. William M. Baird Laboratory
Overview • Introduction • Methods • Summary
Polycyclic Aromatic Hydrocarbons (PAH) • Found in complex environmental pollutants • Formed by incomplete combustion of organic compounds • Human exposure linked to cancer incidence
Dibenzo[a,l]pyrene Dibenzo[a,l]pyrene (DBP) • Related compounds have been shown to be transplacental Anderson, LM, Ruskie, S, Carter, J, Pittinger, S, Kovatch, RM, Riggs, CW. Pharmacogenetics (1995) 6:364-72
PAH Metabolism • Many sites can be epoxidated. • Epoxides are unstable. • Epoxide hydrolase may hydrolyze the epoxide to a diol. • Subsequent epoxide is a more stable, reactive electrophile.
Chen J, et. al. "MMDB: Entrez's 3D-structure database", Nucleic Acids Res. 2003 Jan; 31(1): 474-7.
Mutations by Dibenzo[a,l]pyrene B. Mahadevan, W.-M. Dashwood, A. Luch, A. Pecaj, J. Doehmer, A. Seidel, C. Pereira, and W. M. Baird. Environ. Mol. Mut.41:131-9 (2003)
Objectives • Determine transplacental DNA adduct formation by DBP in mice • Relevance to human health
Methods 17th Day Gestation 15mg DBP/kg body mass Sacrifice via CO2 (maternal) or decapitation (fetal) Lung and liver removed DNA isolated and 33P postlabeled HPLC Analysis
STANDARD DBP HPLC Profiles Controls:
6 Hours 1 Day 2 Days 4 Days 6 Days Maternal Lung Tissue HPLC Profiles
Total DNA Adducts (pmol/mg) Total DNA Adducts in Maternal Lung Tissues
Fetal Lung Tissue HPLC Profiles 2 Day Exposure
Total DNA Adducts After 2 Days Exposure Total DNA Adducts (pmol/mg) Maternal P1 P2 P3 P4 P5 P6 P7
Fetal Liver Tissues • No DNA adducts detected using our method
Summary • DNA adducts found in maternal lung tissues at all exposure times • 2 days exposure to DBP formed DNA adducts in fetal lung tissue • No DNA adducts detected in fetal liver tissue after 2 days exposure
Future Research • DNA adduct determination of: • Maternal Liver • Fetal Lung and Liver at Different Exposure Times
Acknowledgements • Dr. William M. Baird • Dr. Kevin Ahern • Dr. Brinda Mahadevan • Tamara Musafia • Howard Hughes Medical Institute • LARC • Dr. David Williams • Yu Zhen • Mandy Louderback