1. Institute of Biochemistry and Molecular Biology, Ulm University, 89081 Ulm, Germany
2. Leibniz Institute on Aging, Fritz Lipmann Institute, 07745 Jena, Germany
3. Central Facility for Electron Microscopy, Ulm University, 89081 Ulm, Germany
4. Genome Damage and Stability Centre, University of Sussex, Brighton BN1 9RQ, UK