[1] UNIV LA SAPIENZA,DIPARTIMENTO GENET & BIOL MOLEC,CNR,CTR GENET EVOLUZ,PIAZZALE A MORO,I-00185 ROMA,ITALY
[2] CNR,IST CROMATOG,AREA RIC ROMA,I-00016 MONTEROTONDO STN,ITALY
[3] CNR,IST CHIM NUCL,AREA RIC ROMA,I-00016 MONTEROTONDO STN,ITALY
[4] UNIV CATANIA,DEPARTIMENTO BIOL ANIM,I-95124 CATANIA,ITALY