中文摘要：

DEAD-boxRNA解旋酶能介导NTP依赖的双链RNA解旋，大量的研究表明其在植物的各种非生物胁迫的适应过程中发挥着重要作用。本研究从严格嗜冷的南极冰藻Chlamydomonas sp．ICE-L的EST序列中筛选并克隆得到了DEAD-boxRNA解旋酶CiDDX5的全长基因，利用生物信息学软件对该基因编码的蛋白序列进行了研究，并通过实时定量PCR研究了在低温、高盐胁迫下CiDDX5基因表达量的变化。研究结果显示，DEADboxRNA解旋酶CiDDX5基因的编码区长2077bp，编码513个氨基酸。在以氨基酸序列构建的系统进化树中，Ci-DDX5序列和其他绿藻类的聚在一起，与莱茵衣藻，团藻和胶球藻的蛋白序列同源性依次分别为65％，64％和63％。实时定量PCR研究结果表明，在低温和高盐胁迫下，CiDDX5基因的表达量都有一定程度的提高，提示该基因的功能与南极衣藻适应低温、高盐的海冰环境的特性相关。

英文摘要：

DEAD-box helicase not only mediated NTP-dependent double-stranded RNA helix, but also plays an important role in the process of plant adaptation to various abiotic stresses. A DEAD-box RNA helicase CiDDX5 gene was identified from the EST library of the Antarctic ice alga, Chlarnydornonas sp. ICE-L. The complete sequence of the CiDDX5 gene contained an open reading frame of 2,077 bps encoding a RNA helicase of 513 amino acids. Phylogenetic analysis showed that the gene was homologous to the known green algae RNA helicase genes with identities of 65%, 64% and 63% to C. reinhardtii, Volvox carteri and Chlorella vulgaris respectively. The expressions of CiDDX5 gene were up-regulated under both the low temperature and high salinity stress conditions, which indicated the role of CiDDX5 gene in the regulation of abiotic stress adaptation of Antarctic ice alga Chlamydornonas sp. ICE-L.