东莞与邻近地区土沉香居群的叶形态和遗传多样性分析

利用ISSR 技术分析了土沉香也Aquilaria sinensis（Lour.）Gilg.页4 居群的遗传多样性及遗传分化。应用9 条引物从4 个居群共221 份样品中共扩增出105 个位点，其中多态性位点为104 个，多态位点百分率（PPB%）为99.05%。等位基因数（Na）和有效等位基因数（Ne）分别为1.9905 和1.5854；Nei爷s 基因多样性指数（H）为0.3390，Shannon 信息指数（I）为0.5054，表明土沉香种内存在较丰富的遗传多样性。土沉香4 个居群总的遗传变异（Ht）为0.3236，居群内的遗传变异（Hs）为0.2500，居群间的遗传分化系数（Gst）为0.2274，基因流（Nm）为1.6983。UPGMA 聚类分析结果显示，电白居群和大岭山居群优先聚类，然后再与清溪居群聚类，而广西居群与其余3 个居群明显分离，显示出较大的遗传分化；电白居群的大叶类群的分化大于小叶类群；东莞大岭山小叶类群与电白居群遗传相似性较高，而大岭山大叶类群与清溪居群的遗传相似性较高。基于该研究结果，认为东莞大岭山居群部分来自清溪自然居群，部分与电白居群来源相同，它们均来源于海南。

Separation, purification and structure identification of theantimicrobial substances from Antarctic psychrotrophicbacterium Pseudomonas sp. P4-11

The antimicrobial substances of Antarctic psychrotrophic bacterium Pseudomonas sp. P4-11 were studied inthis paper. The results of study on temperature and pH stability of bioactive substances of fermented culture showed that ithad better stability at the range of 30~60 and pH 6~10. By bioassay-guided, two antimicrobial substances (T2-20-7-11-5and T2-20-7-11-7) were isolated by ethyl acetate extraction, silica gel column chromatograph and HPLC. The structure ofT2-20-7-11-5 and T2-20-7-11-7 were both identified as nonylphenol ethoxylates. The effect of T2-20-7-11-5 on theultrastructure of Fusarium oxysporum spore was observed by scanning electron microscope (SEM). The compound mighthave a major role in the cell wall or cell membrane, causing leakage of cell contents and consequently resulting in sporesdeath.