Swiss Institute of Bioinformatics, Centre Médical Universitaire, 1211 Geneva 4, Switzerland. brigitte.boeckmann@isb-sib.ch|Swiss Institute of Bioinformatics, Centre Médical Universitaire, 1211 Geneva 4, Switzerland. brigitte.boeckmann@isb-sib.ch|Swiss Institute of Bioinformatics, Centre Médical Universitaire, 1211 Geneva 4, Switzerland. brigitte.boeckmann@isb-sib.ch|Swiss Institute of Bioinformatics, Centre Médical Universitaire, 1211 Geneva 4, Switzerland. brigitte.boeckmann@isb-sib.ch