This work was supported by the Innovative Experiment Project of Shanxi Normal University Students Grant Nos.SD2011CXSY-9 and SD-2012CXSY-38,and projects from College of Life Science,Shanxi Normal University Grant Nos.SMYKZ-28 and SMYKZ-37.山西师范大学高等学校大学生创新性实验项目SD-2011CXSY-9和SD2012CXSY-38和山西师范大学生命学院项目SMYKZ-28和SMYKZ-37.