中文摘要：

CDC20（celldivisioncycle20）是后期促进复合物（anaphase—promotingcomplex，APC）的共激活剂之一，也是纺锤体组装检查点（spindleassemblycheckpoint，SAC）的靶点，在细胞周期调控中扮演重要角色．为探讨Cdc20在第一极体排出（firstpolarbodyextrusion，PBEI）中的作用，Cdc20基因被成功克隆并构建了真核表达载体pCdc20一Venus，随后用T7MmessageMmachineKit（Ambion）以线性化pCdc20．Venus为模板体外转录（invitrotranscription）获得带帽的Cdc20一VenusmRNA，将Ccdc20．VenusmRNA显微注射到体外培养的牛卵母细胞胞质中进行超量表达．结果表明，真核表达载体pCdc20-Venus转染HeLa细胞后能够正常表达，绿色荧光在细胞核周围呈弥散状分布；将Cdc20．VenusmRNA注射到牛卵母细胞胞质后，胞质内有绿色荧光出现．Cdc20-VenusmRNA注射组卵母细胞的PBEI率（48．9％）与VenusmRNA注射组卵母细胞的PBEI率（50．9％）和未注射组卵母细胞的PBEI率相比均没有显著差异（P〉0．05）．通过Cdc20在牛卵母细胞内的超量表达，结果显示，超量表达Cdc20基因对牛卵母细胞PBEI没有显著影响（P〉0．05）．

英文摘要：

As one of the co-activator of anaphase-promoting complex （ APC）, cell division cycle 20 （CDC20） protein also functions as the target of the spindle assembly checkpoint （SAC）, which is essential for the cell cycle regulation. To investigate the function of Cdc20 during the first polar body extrusion （PBE I）, Cdc20 CDS was cloned and eukaryotic expression vector pCdc20-Venus was constructed. Using the linear pCdc20-Venus as template, the capped Cdc20-Venus mRNA was synthesized via T7 Mmessage Mmachine Kit （Ambion）. Cdc20 over-expression was performed by microinjection of Cdc20-Venus mRNA into the cytoplasm of bovine oocytes. The results showed that Venustagged Cdc20 dispersed around the nucleus in HeLa cells. In bovine oocytes, the fluorescence appeared in the whole cytoplasm. However, the PBE I rate in over-expressed group （48.9%） is not significant, compared to Venus mRNA injection group （50.9%） and non-injection group （51.1%）. Our study demonstrated that the over-expression of Cdc20 in bovine oocytes does not affect the PBE I rate （P 〉 0. 05）.