北柴胡鲨烯合酶基因及其编码区cDNA克隆与序列分析

鲨烯合酶(EC.2.5.1.21,squalene synthase,SS)是植物甾醇和三萜化合物生物合成途径中的关键酶。为研究鲨烯合酶在柴胡皂苷生物合成中的作用,以北柴胡(Bupleurum chinense DC.)不定根为试材,采用Trizol法提取总RNA,利用RT-PCR方法从北柴胡中扩增出了鲨烯合酶cDNA特异片段,并进行了克隆、测序。测序结果显示得到了两个序列不同的cDNA(BcSS1和BcSS2),分别为1245bp和1248bp,分别编码414及415个氨基酸。BcSS1和BcSS2间的核苷酸和氨基酸一致性分别为98%和96%。NCBI Blastx结果显示与三岛柴胡和三七SS氨基酸序列相似性最高,BcSS1的一致性分别为99%和90%,BcSS2的分别为97%和87%。在此基础上,利用PCR技术从北柴胡不定根中扩增得到了一个SS基因克隆,长5880bp,包含12个内含子。     

Effect of storage time and preservatives on vitamin and pigment contents of canned tomato soup

Five varieties of Amaranthus cruentus were planted in 3 localities at different altitudes above sea level. They were subjected to equivalent agronomic practices and harvested at 120–130 days. The seeds were removed and dried to 12% moisture. The seeds from each variety were analyzed for total fat, palmitic, stearic, oleic and linolenic acids and squalene contents. Oil content varied from 5.83 to 7.13%, palmitic acid from 17.06 to 21.35%, stearic acid from 3.05 to 3.80%, oleic acid from 20.26 to 32.01% and linoleic acid from 33.52 to 43.88%. The values for oil and fatty acid contents were similar to those found in the literature. The differences in the analytical values of the present study were not statistically significant for variety or for location.Squalene content varied from 2.26 to 5.94% of the oil. This variability is similar to that reported previously by other workers. Statistical analysis showed significant difference for localities but not for varieties. It is suggested that environmental conditions, such as temperature and water availability, may lead to a greater accumulation of squalene in the grain.