Center for Bioinformatics, Saarland University, Saarbrücken, Germany. ack@bioinf.uni-sb.de|Center for Bioinformatics, Saarland University, Saarbrücken, Germany. ack@bioinf.uni-sb.de|Center for Bioinformatics, Saarland University, Saarbrücken, Germany. ack@bioinf.uni-sb.de|Center for Bioinformatics, Saarland University, Saarbrücken, Germany. ack@bioinf.uni-sb.de|Center for Bioinformatics, Saarland University, Saarbrücken, Germany. ack@bioinf.uni-sb.de|Center for Bioinformatics, Saarland University, Saarbrücken, Germany. ack@bioinf.uni-sb.de|Center for Bioinformatics, Saarland University, Saarbrücken, Germany. ack@bioinf.uni-sb.de|Center for Bioinformatics, Saarland University, Saarbrücken, Germany. ack@bioinf.uni-sb.de