1. Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia B3H 1X5, Canada.
2. Institute of Parasitology, Czech Academy of Sciences and Faculty of Sciences, University of South Bohemia, 37005 České Budĕjovice, Czech Republic.
3. Department of Botany, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.