1. Department of Biotechnology and Bioengineering, Chonnam National University, Gwangju 500-757, South Korea
2. Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongup 580-185, South Korea
3. Department of Biology, Kongju National University, Konju 314-701, South Korea
4. Korea Polar Research Institute, Incheon 406-840, South Korea