1. Center for Bioinformatics, Quantitative Biology Center, and Department of Computer Science, University of Tübingen, Sand 14, 72076 Tübingen, Germany
2. Technische Universität Dresden, Zellescher Weg 12-14, 01069 Dresden, Germany
3. Ludwig-Maximilians-Universität München, Butenandtstr aße 5-13, 81377 München, Germany
4. Center for Research Computing, University of Notre Dame, P.O. Box 539, Notre Dame, IN 46556, USA