超临界CO_2提取茶叶中咖啡碱

用超临界萃取技术分离提取茶叶中的咖啡碱，再用CH2Cl2萃取分离，得到纯度为95．16％的咖啡碱，萃取率和得率分别为16．85％、0．55％。试验结果还表明，在一定条件下，利用超临界萃取技术能够有效地分离茶多酚和咖啡碱。     

Alkaloid accumulation in capsules of the selfed and cross-pollinated poppy

In harmony with international regulations the creation of poppy cultivars with high alkaloid content as well as free of alkaloids is in progress. In the course of selection procedures, five poppy cultivars of high chemical diversity, ‘Kheops’, ‘AT, ‘Tebona’, ‘Kék Gemona’ and ‘Przemko’, were selfed and crossed in two successive years (2000‐01). After full ripening, both the biomass production and the alkaloid content of capsules of selfed and crossed plants were determined. When the castrated alkaloid‐free cultivar ‘Przemko’ (accumulating only 0.01 mg/100 g morphine in capsules) was pollinated with cultivars rich in alkaloids, the morphine content of its capsules increased to 0.9‐7.5 mg/100 g‐values. Based on the well‐known biosynthetic background of poppy alkaloids, this can be explained by promotion of (S)‐norcoclaurine synthesis, which seems to be suppressed in alkaloid‐free plants; but tissues of the developing hybrid seeds, which contain a combined gene pool of both alkaloid‐free cultivar and that of the pollen donor plants, release this suppression. The chemical metaxenia also manifested itself in other combinations. In particular, the appearance of narcotine (0.1‐1.1 mg/100 g) in the narcotine‐free cultivars ‘Kheops’, ‘A1’ and ‘Przemko’ can be explained biochemically. If the narcotine‐type plants ‘Kék Gemona’ (accumulating 11.3 mg/g narcotine) were used for pollination, the developing seed tissue, which contains the gene pool of narcotine biosynthesis, might contribute to the suppression of the activity of 1,2‐dehydroreticuline reductase, which leads to the accumulation of narcotine at the cost of morphinanes.     

不同年龄三七根皂甙合成相关基因的差减cDNA文库构建

本研究以三七3年生根和1年生根为材料,利用抑制消减杂交技术构建三七根在不同年龄阶段皂甙合成相关基因的差减cDNA文库,正向文库(3年生文库)和反向文库(1年生文库)分别包括2000个和500个cDNA克隆,重组率在95%以上;外源片段的长度分布在200～900bp,平均片段长度约500bp;差减效率检测表明:消减前后基因的拷贝数相差32000倍,差异表达的基因得到了充分的富集。结果表明所构建的cDNA文库符合SSH文库的质量标准,能够满足下一步的实验要求,为研究差异表达基因,探讨皂甙生物合成的分子机理,提高三七皂甙产量产量和质量奠定基础。     

杆菌肽合成分子机制及高产策略

杆菌肽是一种非核糖体肽类的广谱抗菌素,目前广泛应用于农业和医药。过去,杆菌肽的生产水平增长缓慢。近年来国内外对杆菌肽的生物合成及调控的分子机制研究取得较大突破,为其育种和生产工艺优化、提高产量和质量、满足市场需求奠定基础。综述了国内外相关文献,重点关注杆菌肽生物合成基因簇及调节分子机制,兼顾其产量提高策略的报道,为今后开展相关育种研究、发酵工艺优化和提高杆菌肽的产量提供依据。     

大豆吡哆醇生物合成蛋白基因(PDX)的电子克隆和进化分析

电子克隆(In silicocloning)是随着基因组计划和EST计划实施而发展起来的利用生物信息学手段进行基因克隆的新方法。根据物种间同源基因相对保守的特点,以拟南芥(Arabidopsis thaliana)吡哆醇生物合成蛋白cDNA序列为信息探针,对大豆(Glycine max)EST数据库进行同源搜索和序列拼接,获得了1 280 bp长的大豆吡哆醇生物合成蛋白的基因序列(GenBank登陆号为DQ139265)。经过RT-PCR扩增、基因组PCR扩增、分子克隆和序列分析验证,结果表明与电子克隆序列完全一致。该基因具有完整的开放阅读框架(ORF,20~955 bp),编码311个氨基酸。通过与水稻、日本百脉根、烟草、截形苜蓿等物种的吡哆醇生物合成蛋白序列比对,发现该基因具有高度的保守性。表明根据物种间同源基因序列,对跨物种间EST数据库进行同源检索、筛选、拼接,是克隆基因的有效途径。     

Identification and fine mapping of a candidate gene for oil yellow leaf 2 conferring yellow leaf phenotype in maize

Leaf colour is an important agronomic trait for studying molecular mechanisms in chlorophyll biosynthesis and chloroplast development. Here, a novel mutant oil yellow leaf 2 (Oy2) with a typical yellow leaf phenotype at the seedling stage was identified from the mutant population derived from the maize inbred line RP125. Compared with wild type, Oy2 mutant displays decreased chlorophyll content, reduced photosynthetic capacity and impaired chloroplast structure, which is likely controlled by a single recessive gene. The Oy2 locus was then delimited into a 117 kb region on chromosome 5 harbouring four genes, amongst which the gene Zm00001d013013, encoding a magnesium chelatase subunit D, was identified as the only candidate gene associated with Oy2 mutant phenotype. Moreover, the expression levels of candidate gene Oy2 and genes associated with chlorophyll biosynthesis and photosynthesis were tested by RNA‐seq and qRT‐PCR, implying that the causal gene Oy2 playing a critical role in chlorophyll synthesis. Taken together, we propose that the causal gene Oy2 highly associated with the yellow leaf phenotype may be helpful in elucidating photosynthetic pigments biosynthesis and chloroplast development in maize.     

The Inheritance of Aliphatic Glucosinolates in Brassica napus

The inheritance of aliphatic glucosinolates was studied in crosses between synthetic B. napus lines and oilseed rape cultivars. Six unlinked loci are described which determine the aliphatic glucosinolate profile of B. napus. One locus regulates the presence or absence of propyl glucosinolates, while another regulates the expression of pentyl glucosinolates. Two loci regulate the removal of the terminal H₃CS-group from the amino acid derivative to produce alkenyl glucosinolates as opposed to methylthioalkyl and methylsulphinylalkyl glucosinolates, regardless of the length of the alkyl chain. Likewise, another two loci regulate the hydroxylation of both butenyl and pentenyl glucosinolates. The functional alleles at one of the hydroxylation loci results in significantly more hydroxylation than those at the other locus. The large number of aliphatic glucosinolates which have been described in Brassica thus results from an interaction between genes which regulate side chain elongation and genes which modify the structure of the side chain, regardless of its length. The implications of this study for the biosynthesis of aliphatic glucosinolates, the origin of B. napus and the potential to manipulate the leaf and seed glucosinolate profile of oilseed rape are discussed.     

Screening of extracts of Japanese woods for melanin biosynthesis inhibition

The effects of 120 methanol extracts prepared from bark and heartwood of 69 types of Japanese wood on the melanin production of B16 melanoma cells were examined. The melanin content of B16 melanoma cells was determined spectrophotometrically at 405nm. The extracts were also examined for their effects on cell viability. We found that the methanol extracts of Fagus crenata (buna, wood, 100μg/ml), Sapium sebiferum (Nankinhaze, wood, bark, 10μg/ml), and Zelkova serrata (keyaki, wood, 10μg/ml) greatly inhibited the melanin production of B16 melanoma cells without significant cytotoxicity. However, these extracts did not inhibit tyrosinase activity at the concentration of 100μg/ml. These findings indicate that the depigmenting mechanism of these extracts involves the suppression of some pigmenting signals in stimulating melanogenesis rather than the inhibition of tyrosinase activity. Part of this study was presented at the 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, Japan, March 2003     

长链燃料醇生物合成研究进展

简单介绍了长链醇作为液体燃料的优良性能,综述了长链醇生物合成的3条主要途径(Ehrlich途径、非发酵途径和光合途径),并进一步从宿主菌株选择、耐受菌株选育、代谢通路疏通以及产醇工艺优化等方面概述了提高长链醇产量的方法,最后对长链醇未来的研发方向进行了展望。