Center for Bioinformatics, University of Hamburg, Bundesstrasse 43, 20146 Hamburg, Germany. beckstette@zbh.uni-hamburg.de|Center for Bioinformatics, University of Hamburg, Bundesstrasse 43, 20146 Hamburg, Germany. beckstette@zbh.uni-hamburg.de|Center for Bioinformatics, University of Hamburg, Bundesstrasse 43, 20146 Hamburg, Germany. beckstette@zbh.uni-hamburg.de|Center for Bioinformatics, University of Hamburg, Bundesstrasse 43, 20146 Hamburg, Germany. beckstette@zbh.uni-hamburg.de