1. Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley , Berkeley, CA 94720 , USA
2. State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences , Beijing 100101 , China
3. University of Chinese Academy of Sciences , Beijing 100093 , China
4. Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences , Kunming, Yunnan 650223 , China