1. Institute of Botany III, University of Düsseldorf, Düsseldorf 40225, Germany
2. National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health Bethesda, MD 20894, USA
3. University of Connecticut, Biology/Physics Building, 91 North Eagleville Road, Storrs, CT 06269-3125, USA
4. Molecular Biology Institute, Departments of Molecular, Cell, and Developmental Biology, Human Genetics, and National Aeronautics and Space Administration, Astrobiology Institute, University of California, Los Angeles, CA 90095, USA