1. College of Animal Sciences, Zhejiang University, Hangzhou, Zhejiang 310030, P. R. China
2. MOE Key Laboratory of Biosystems Homeostasis & Protection, and Zhejiang Provincial Key Laboratory of Cancer Molecular Cell Biology, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310030, China
3. Department of Animal and Veterinary Sciences, University of Vermont, Burlington, Vermont 05405, United States