1. Institute of Biomedicine, Department of Anatomy, University of Helsinki, PO Box 9, 00014, University of Helsinki, Finland,
2. Institute of Biotechnology and Department of Biosciences, University of Helsinki, Biocentre 2, PO Box 56, 00014 University of Helsinki, Finland,
3. Department of Biology, Åbo Akademi University, Biocity, Artillerigatan 6, 20150 Åbo, Finland