Institute of Biotechnology, University of Helsinki, P.O.Box 56 (Viikinkaari 5), FIN-00014 University of Helsinki, Finland.|Institute of Biotechnology, University of Helsinki, P.O.Box 56 (Viikinkaari 5), FIN-00014 University of Helsinki, Finland.|Institute of Biotechnology, University of Helsinki, P.O.Box 56 (Viikinkaari 5), FIN-00014 University of Helsinki, Finland.