1. From the Institute of Anatomy and Cell Biology, University of Freiburg, Freiburg, Germany; the
2. Department of Developmental Biology and Neurogenetics, Institute for Zoology, Darmstadt University of Technology, Darmstadt, Germany; the
3. Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, Utah; and the
4. Department of Biochemistry, Nijmegen Center of Molecular Life Sciences, University of Nijmegen, Nijmegen, The Netherlands.