中文摘要：

根据几个已知的植物ω3脂肪酸脱饱和酶基因序列，利用RT-PCR和RACE技术从麻疯树中克隆了一条编码叶绿体ω3脂肪酸脱饱和酶的cDNA序列．对该序列的分析表明，该cDNA的编码区长1368bp，编码一个长度为455个氨基酸的蛋白质，推测的蛋白质相对分子质量（Mr）大小为52．1×10^3．同源分析显示，推测的氨基酸序列与其他植物叶绿体脂肪酸脱饱和酶具有很高的相似性．RT-PCR分析表明，该基因在麻疯树叶片中有着稳定的表达．此外，还通过酵母表达系统鉴定了该基因编码的酶的功能．对转基因酵母的脂肪酸组成分析发现，α亚麻酸在转基因酵母中积累．上述结果表明，该麻疯树cDNA编码了一个叶绿体ω3脂肪酸脱饱和酶．图4表2参21

英文摘要：

Based on the sequence information of the ω3-fatty acid desaturase genes from Arabidopsis thaliana, Nicotiana tabacum, Betula pendula and Ricinus communis, a cDNA putatively encoding a plastidial ω3-fatty acid desaturase （JcFAD7） was isolated from Jatroha curcas with reverse transcription polymerase chain reaction （RT-PCR） and rapid amplification of cDNA ends （RACE） method. Sequence analysis revealed that this cDNA sequence had an open reading frame （ORF） of 1 368 bp encoding 455 amino acids of 52. 1×10^3 （Mr）. Homology analysis showed that the deduced amino acid sequence of this cDNA exhibited high identity to the plastidial ω3-fatty acid desaturase. RT-PCR analysis indicated that this plastidial ω3 desaturase had a constitutive expression in the leaf of J. curcas. In this study, the function of this putative desaturase was identified by heterologous expression in Saccharomyces cerevisiae strain INVScl. The analysis of the fatty acids of yeast transformants showed that α-linolenic acid was accumulated in the yeast. These results suggest that this cDNA encodes a plastidial ω3-fatty acid desaturase inJ. curcas, Fig 4, Tab 2, Ref21