1. Bioinformatics Research Group, SRI International, Menlo Park, CA 94025
2. Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, A.P. 565-A, Cuernavaca, Morelos 62100, México
3. Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, CA 90095
4. UCLA Institute of Genomics and Proteomics, University of California, Los Angeles, CA 90095
5. Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW 2109, Australia