1. Center for Environmental and Genetic Medicine, Institute of Biosciences and Technology, Texas A&M University System Health Science Center, Houston, TX 77030
2. Center for Human Molecular Genetics, University of Nebraska Medical Center, Omaha, NE 68198
3. National Veterinary Research Institute, 24-100 Pulawy, Poland
4. National Center for Toxicological Research, Division of Biochemical Toxicology, Jefferson, AR 72079