Genome Informatics, Faculty of Technology and Center for Biotechnology (CeBiTec), Bielefeld University, Germany, Center for Bioinformatics, Saarland University and Department of Computational Biology and Applied Algorithmics, Max Planck Institute for Informatics, Saarbrücken, Germany, Centrum Wiskunde & Informatica (CWI), Life Sciences Group, Amsterdam, The Netherlands and Helsinki Institute for Information Technology (HIIT), Department of Computer Science, University of Helsinki, Finland.