[1] FAC AGRON GEMBLOUX,B-5800 GEMBLOUX,BELGIUM
[2] UNIV LIBRE BRUXELLES,DEPT MOLEC BIOL,B-1640 RHODE ST GENESE,BELGIUM
[3] INT INST CELLULAR & MOLEC PATHOL,B-1200 BRUSSELS,BELGIUM
[4] SMITHKLINE BIOL,DEPT MOLEC & CELLULAR BIOL,B-1330 RIXENSART,BELGIUM