1. FlyBase, Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, UK, 2FlyBase, Department of Biology, Indiana University, 1001 East 3rd Street, Bloomington, IN 47405-7005, USA and 3Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK