1. Department of Biomolecular Sciences and Biotechnology, CNR‐INFM, University of Milano Via Celoria 26 Milano 20133 Italy
2. Department of Physics, CNR‐INFM and CEBR, University of Genova Via Dodecaneso, 33 Genova 16146 Italy
3. Department of Biomedical Sciences, University of Antwerp, Universiteitsplein 1 Antwerp B‐2610 Belgium
4. Department of Microbiology, University of Hawaii Snyder Hall 207, 2538 The Mall, Honolulu Hawaii 96822 USA
5. Department of Biology and Interdepartmental Laboratory for Electron Microscopy, University Roma Tre Viale Guglielmo Marconi 446 Roma 00146 Italy
6. Department of Experimental Medicine and Biochemical Sciences, University of Roma ‘Tor Vergata’ Via di Tor Vergata 135 Roma 00133 Italy