1. The Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
2. The Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK
3. The Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, UK
4. The Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EH, UK
5. The Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
6. Institute for Adaptive and Neural Computation, University of Edinburgh, 10 Crichton Street, Edinburgh EH8 9AB, UK
7. Cardiff School of Biosciences, The Sir Martin Evans Building, Museum Avenue, Cardiff CF10 3AX, UK
8. Department of Genetics, University of Leicester, Adrian Building, University Road, Leicester LE1 7RH, UK
9. Centre for Advanced Microscopy, University of Sussex, School of Life Sciences, John Maynard Smith Building, Falmer, Brighton and Hove BN1 9QG, UK