[1] INST PASTEUR, BIOL MOLEC GRP,UNITE GENIE GENET,CNRS, EQUIPE RECH 201, F-75015 PARIS, FRANCE
[2] CNRS, GENET MOLEC EUCARYOTES LAB, F-67000 STRASBOURG, FRANCE
[3] FAC MED STRASBOURG, INSERM, UNITE BIOL MOLEC & GENIE GENET 184, F-67085 STRASBOURG, FRANCE