1. Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109.
2. Molecular Control and Genetics Section, Laboratory of Chromosome Biology, ABL-Basic Research Program, National Cancer Institute-Frederick Cancer Research and Development Center, Frederick, MD 21702.
3. Imaging Processing Section, Laboratory of Mathematical Biology, National Cancer Institute- Frederick Cancer Research and Development Center, Frederick, MD 21702.