[1] CNRS, INST BIOL MOLEC & CELLULAIRE, 15 RUE DESCARTES, F-67084 STRASBOURG, FRANCE
[2] POLISH ACAD SCI, INST BIOORGAN CHEM, PL-60479 POZNAN, POLAND
[3] ACAD SCI USSR, INST MOLEC BIOL, MOSCOW V-71, USSR
[4] UNIV ZURICH, INST ZOOL, CH-8006 ZURICH, SWITZERLAND