中文摘要：

发菜是一种分布在干早、半干旱荒漠草原地区的陆生固氮蓝藻，对干旱具有极强的适应性。采用qRT—PCR技术，对干旱胁迫条件下发菜cphB的差异表达进行了分析，发现干旱胁迫条件下发菜cphB在转录水平上呈逐渐增加的趋势。根据发菜同源物种设计简并性引物克隆cphB基因，获得长度为864bp的DNA（GenBank登陆号为KX092456）。同源性比较发现发菜cphB基因具有较高的保守性，二级结构预测表明发菜CphB由α螺旋，β折叠和随机卷曲构成。三级结构预测表明CphB具有一个由α螺旋和β折叠组成的5股的结构域和由7个β折叠连成三明治结构的7股的结构域。将cphB基因在大肠杆菌中表达，获得符合预期的外源重组蛋白，CphB亚细胞定位于细胞质中。研究成果为进一步研究干旱胁迫条件下发菜cphB表达调控、藻蓝素的代谢机制及能量代谢机制方面奠定了基础。

英文摘要：

Nostoc flagelliforme is a terrestrial nitrogen-fixing cyanobacte ria distributed in dry and semi arid desert steppe areas, which has strong adaptability to drought. We used qRT-PCR technique to analyze the differ- ential expression of ephB from Nostoe flagelliforme under drought stress conditions and found that cphB gradual- ly increased at the transcription level under drought stress. Degenerate primers were designed according to ho- mologous species of Nostoc flagelliforme to clone cphB gene, and a DNA with the full length of 864 bp was ob- tained （GenBank access number： KX092456）. Homology comparison showed that cphB gene had high conser- vatism, and the secondary structure prediction indicated that CphB was made up of α Helix, 13 sheet and random coil. Besides, tertiary structure prediction demonstrated that CphB had a 5-stranded domain that composed of α Helix and β sheet and a seven-stranded domain composed of 7 β sheet with the structure like sandwich. The cphB was expressed in Escherichia coli, and the desired exogenous recombinant protein was obtained. In addi- tion, CphB subcellular was located in the cytoplasm. The results laid a foundation for further study on expres sion and regulation of cphB, metabolic mechanism of phycocyanin and energy metabolism in Nostoc flageUi- forme under drought stress.