1. Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201, USA
2. Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
3. Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250, USA
4. Department of Biology, Texas A&M University, College Station, TX 77840, USA
5. Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77840, USA
6. Molecular Ecosystems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA