1. Department of Vertebrate Genomics, Molecular Embryology and Aging group, Max Planck Institute for Molecular Genetics, Berlin, Germany.
2. Department of Biology, Chemistry and Pharmacy, Freie Universität Berlin, Berlin, Germany.
3. Institute for Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany.
4. Electron Microscopy Group, Max Planck Institute for Molecular Genetics, Berlin, Germany.
5. Institute for Stem Cell Research and Regenerative Medicine, Faculty of Medicine, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany.