1. College of Food Science and Engineering, Northwest A&F University, Yangling, 712100 Shaanxi, P. R. China
2. School of Medicine, Xi’an Jiaotong University, Xi’an, 710061 Shaanxi, P. R. China
3. Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, 810008 Qinghai, P. R. China