1. National Genomics Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation , Beijing 100101, China
2. CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation , Beijing 100101, China
3. University of Chinese Academy of Sciences , Beijing 100049, China
4. Department of Biology, The University of Western Ontario , London , Ontario N6A 5B7, Canada