1. Centre for Molecular Biology and Neuroscience and Institute of Microbiology, Rikshospitalet-Radiumhospitalet Medical Centre, Oslo, Norway
2. Centre for Molecular Biology and Neuroscience and Institute of Microbiology, University of Oslo, Oslo, Norway
3. Faculty of Life Sciences, The University of Manchester, Manchester Interdisciplinary Biocentre, 131 Princess Street, Manchester M1 7DN, UK