Comparative Genomics group, Bioinformatics and Genomics Programme, Centre for Genomic Regulation, Barcelona, Spain. jhuerta@crg.es|Comparative Genomics group, Bioinformatics and Genomics Programme, Centre for Genomic Regulation, Barcelona, Spain. jhuerta@crg.es|Comparative Genomics group, Bioinformatics and Genomics Programme, Centre for Genomic Regulation, Barcelona, Spain. jhuerta@crg.es