1. Department of Mathematics and Molecular Biology, University of Southern California, Los Angeles, California 90089
2. Department of Statistics, University of Georgia, Athens, Georgia 30602
3. Department Of Microbiology And Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma 74078
4. Department of Molecular Biology, Jilin University, Chang Chun 130023, People’s Republic of China
5. Department of Genetics, University of Georgia, Athens, Georgia 30602, and
6. Myco Pharmaceuticals, Inc., Cambridge, Massachusetts 02139