Department of Computer Science, University of Salamanca, 37008 Salamanca, Spain and Instituto de Biología Funcional y Genómica, CSIC/USAL, 37007 Salamanca, SpainDepartment of Computer Science, University of Salamanca, 37008 Salamanca, Spain and Instituto de Biología Funcional y Genómica, CSIC/USAL, 37007 Salamanca, Spain.