1. Department of Anatomy, College of Veterinary Medicine, Chonnam National University, Puk-Ku, Kwangju, South Korea
2. Department of Biology, College of Natural Science, Sunchon National University, Sunchon, South Korea
3. Radiation Food Science and Biotechnology Team, Korea Atomic Energy Research Institute, P.O. Box 105, Yusong, Taejon 305-600, South Korea