中文摘要：

本研究对蛇足石杉（Huperzia serrata）环阿屯醇合成酶（Cycloartenol synthase,CAS）基因HsCAS1编码区进行克隆及序列分析。根据本实验室已获得的蛇足石杉转录组数据,从中获得1条具有环氧角鲨烯环化酶保守结构域的编码CAS的转录本,采用RT-PCR方法获得该基因的编码区序列,并对HsCAS1蛋白进行理化性质、蛋白二级结构及三维结构预测分析。利用实时荧光定量PCR方法检测HsCAS1基因在蛇足石杉的根、茎、叶中的表达情况。序列分析表明,所克隆的HsCAS1基因编码区长为2,271 bp,编码756个氨基酸残基,HsCAS1与紫果冷杉（Abies magnifica）的CAS具有61%的序列相似性。生物信息学预测HsCAS1蛋白含有3个跨膜区,具有萜类环化酶等保守结构域,不含信号肽。HsCAS1在蛇足石杉的根中表达丰度高于茎和叶。本研究在国内外首次获得蛇足石杉HsCAS1基因的编码区序列,为进一步研究HsCAS1在石杉科植物甾醇合成途径中的功能及鉴定酶活性位点奠定基础。

英文摘要：

This study aimed to clone and analyze the open reading frame of cycloartenol synthase（CAS） from Huperzia serrata.After searching the transcriptome dataset of H.serrata,one unique sequence containing oxide squalene cyclases domain was discovered.The primers were designed according to the transcript sequence of HsCAS1 from the dataset.And then,the open reading frame of cycloartenol synthase was cloned by RT-PCR strategy from H.serrata.The bioinformatic analysis of this gene and its corresponding protein was performed.A cDNA clone（HsCAS1） encoding cycloartenol synthase（CAS） has been isolated from H.serrata by RT-PCR method.The cDNA contains a 2,271-bp open reading frame and encodes a predicted protein of 756 amino acids with high homology（61%） to Abies magnifica cycloartenol synthase.HsCAS1 contains three transmembrane regions and the conserved domain of terpenoid cylases,without signal peptide.HsCAS1 was more abundant in H.serrata root than in leaf and stem.This study cloned and analyzed cycloartenol synthase（CAS） gene from H.serrata for the first time.The result will provide a foundation for exploring the mechanism of sterol biosynthesis in H.serrata plants.