青藏高原不同海拔高度下全缘叶绿绒蒿叶表皮特征研究

采用胶带粘取叶表皮法,利用光学显微镜观测不同海拔高度下全缘叶绿绒蒿叶片的表皮毛、气孔及表皮细胞结构特征,探讨全缘叶绿绒蒿叶表皮特征与海拔高度的关系。结果表明,随着海拔高度增加,全缘叶绿绒蒿叶片上、下表皮毛密度、气孔密度和表皮细胞密度逐渐增加;气孔器及表皮细胞的长度、宽度和面积逐渐减小;表皮细胞的形态随着海拔升高由无规则形向多边形变化,垂周壁由波状向弓形或平直变化。全缘叶绿绒蒿叶表皮结构在不同海拔高度下表现出的差异,可能是植物长期在高原生态环境下的综合反应,以结构上的变化来适应对高海拔地区的环境特点,为进一步研究高海拔地区植物的适应性提供一定依据。     

Spirostanol saponins from the rhizomes of Tacca chantrieri and their cytotoxic activity

The rhizomes of Tacca chantrieri have been analysed for steroidal saponin constituents, resulting in the isolation of four new spirostanol saponins (1-4), along with one known saponin (5); their structures were elucidated on the basis of extensive spectroscopic analysis, including 2D NMR, and the results of hydrolytic cleavage. The isolated compounds were evaluated for their cytotoxic activity against HL-60 human promyelocytic leukemia cells.     

全缘叶绿绒蒿挥发性组分定量结构-色谱保留关系研究

提出顶点及顶点相互作用矢量的概念,并将该矢量用于复杂样本的分子结构表征。采用逐步回归结合统计检测对变量进行筛选后,再用多元线性回归建立了定量结构-色谱保留(QSRR)关系的7变量模型,模型的建模计算值复相关系数(R)为0.990,标准偏差(SD)为1.325;留一法(LOO)交互检验复相关系数(RCV)为0.983,标准偏差(SDCV)为1.696。结果表明该矢量具有较强的分子结构表达能力,模型具有良好的估计能力与稳定性。     

Ultrastructure of Macadamia (Proteaceae) embryos: implications for their breakage properties

BACKGROUND AND AIMS: Macadamia integrifolia, M. tetraphylla and their hybrids are cultivated for their edible kernels. Whole kernels, i.e. intact mature embryos with cotyledons fused together, are highly valued and breakage of embryos into halves results in loss of value for the commercial macadamia industry. The morphology and ultrastructure of the mature macadamia embryo, with particular emphasis on the break zone between cotyledons, were investigated. Differences in breakage between different macadamia cultivars were also examined. METHODS: Manual cracking was used to compare breakage in five cultivars and the ultrastructure of the break zone between the cotyledons was examined using light and transmission electron microscopy. KEY RESULTS: Breakage of macadamia embryos was strongly dependent on genotype of the female parent, with cultivars 'HAES 344' and 'HAES 741' much more likely to break than 'HV A16' and 'HAES 835'. Cotyledons were surrounded by a layer of cuticle resulting in a double cuticle in the break zone between the cotyledons. Three major differences have been found in the ultrastructure of the double cuticle between cultivars: a thicker cuticle in the low-whole cultivar; convolutions in the cuticle of a low-whole cultivar, and the presence of more electron-dense objects in the high-whole cultivar. CONCLUSIONS: Breakage of macadamia embryos depends on the cultivar, with clear ultrastructural differences in the break zone between cultivars. To ensure commercial benefits, macadamia breeding programs should identify germplasm with structural characteristics that ensure high percentages of whole kernel.     

The mode of action of the plant antimicrobial peptide MiAMP1 differs from that of its structural homologue, the yeast killer toxin WmKT

The plant antimicrobial peptide MiAMP1 from Macadamia integrifolia and the yeast killer toxin peptide WmKT from Williopsis mrakii are structural homologues. Comparative studies of yeast mutants were performed to test their sensitivity to these two antimicrobial peptides. No differences in susceptibility to MiAMP1 were detected between wild-type and several WmKT-resistant mutant yeast strains. A yeast mutant MT1, resistant to MiAMP1 but unaffected in its susceptibility to plant defensins and hydrogen peroxide, also did not show enhanced tolerance towards WmKT. It is therefore probable that the Greek key beta-barrel structure shared by MiAMP1 and WmKT provides a robust structural framework ensuring stability for the two proteins but that the specific action of the peptides depends on other motifs.     

New glycosides of the campesterol derivative from the rhizomes of Tacca chantrieri

Seven new glycosides of the campesterol derivative (24R,25S)-ergost-5-ene-3beta,26-diol (1-7) were isolated from the rhizomes of Tacca chantrieri (Taccaceae). Their structures were determined by extensive spectroscopic analysis, including 2D NMR data, and a few chemical transformations.     

Photosynthesis of herbaceous plants from nutrient-poor tropical forests

Photosynthetic characteristics, specific leaf mass, chlorophyll and total leaf nitrogen concentrations of four herbaceous plants (Dicranopteris linearis, Hanguana malayana, Pentaphragma ellipticum, Tacca integrifolia) from nutrient-poor tropical forests showed that all these plants were well-adapted to their natural growth environments. No photoinhibition was observed even in the understorey plants. This revised version was published online in June 2006 with corrections to the Cover Date.     

Iridoids of Chemotaxonomy Relevance,a New Antirrhinoside Ester and Other Constituents from Kickxia spuria subsp. integrifolia (Brot.) R.Fern.

In this work, the secondary metabolite content of the EtOH extract of Kickxia spuria subsp. integrifolia (Brot .) R.Fern . is reported. Fourteen compounds were isolated and identified by means of column chromatography and NMR and MS instrumental techniques, respectively. Among the identified compounds, the chemotaxonomic markers of the species were evidenced, whereas others were reported for the first time in the genus. Among these, a new antirrhinoside derivative ( 12 ) was recognized. The iridoid content showed a molecular pattern very similar to those reported for other taxa comprised in the Antirrhinae tribe of Plantaginaceae, thus providing an additional evidence that supports the current botanical classification of the Kickxia genus. Anyway, most of the recognized components are able to exert important pharmacological properties which might suggest the possible employment of also this species in traditional medicine just like it happens for some other species of the Kickxia genus.     

雅鲁藏布江河谷丝须蒟蒻薯遗传多样性的初步研究

分布于雅鲁藏布江河谷的丝须蒟蒻薯(Taccaintegrifolia)与其在东南亚的主要分布区具有明显的间断分布格局。为了探讨地理隔离对其居群遗传结构和遗传多样性的影响,我们应用ISSR分子标记方法对采自西藏墨脱的3个丝须蒟蒻薯居群共65个个体进行了遗传多样性和居群遗传结构分析,并与马来西亚Seremban的1个居群(19个个体)进行了比较。19个ISSR引物共扩增到165个位点,其中111个为多态位点,占67.68%。丝须蒟蒻薯在物种水平上的遗传多样性虽然不低(PPB=67.68%,HT=0.185,Hsp=0.292),但在居群内的遗传多样性却非常低(PPB=12.81%,HE=0.065,Hpop=0.044)。与马来西亚居群(Ma)(PPB=31.71%)相比,墨脱的3个居群遗传多样性极低(PPB分别为3.66%,8.54%,7.32%)。Ma居群与墨脱居群相隔2000km以上,两个地区间的遗传分化程度很大(GST=0.777,FST=0.9206),而墨脱的3个居群间(0.28%)及居群内(7.94%)的遗传分化却非常低(P<0.001)。居群间极其有限的基因流(Nm=0.1435)可能是由于该物种是以自交为主的种类、种子散布很困难、居群间的隔离、生境的破碎化等原因所致。总之,雅鲁藏布江河谷地区特殊的地形和地貌以及与其他热带地区的地理隔离是造成丝须蒟蒻薯在这一地区遗传多样性极低的可能原因。