卧龙自然保护区不同海拔的中国沙棘(Hippophae rhamnoides subsp. sinensis)天然群体的遗传多样性分析

中国沙棘是一种雌雄异株、风媒传粉的灌木或乔木，在中国西南的卧龙自然保护区有广泛的分布。本研究以采集于四川卧龙自然保护区5 个海拔(1800 m、2200 m、2600 m、3000 m、3400 m)梯度的中国沙棘天然群体为材料，以ISSR 和AFLP 标记技术研究其遗传多样性水平及其遗传结构，旨在了解卧龙地区中国沙棘天然群体的遗传多样性水平以及遗传多样性在群体间、群体内以及雌雄亚群体间的分布和特征，为中国沙棘树种的遗传改良及种质资源保存提供遗传研究背景与实验依据。同时探讨ISSR、AFLP 和RAPD三种标记对中国沙棘天然群体的遗传变异水平和群体间遗传结构的评估能力和各自的优缺点。研究得出以下主要结论： 1. ISSR和AFLP分析都表明卧龙自然保护区的中国沙棘群体拥有较高的遗传变异水平(h = 0.249，HT = 0.305)。出现这种结果的主要原因可能与卧龙自然保护区多变的气候条件和生境的异质度大有关。 2. ISSR 和AFLP 都揭示出卧龙自然保护区中国沙棘群体的遗传多样性随着海拔的增加发生显著的变化，表现为中海拔群体(2200 m 和2600 m)比高海拔群体(3000 m 和3400 m)和低海拔群体(1800 m)有更高的遗传多样性的趋势。出现这种趋势的可能解释是低海拔群体处在相对高温和相对干旱的环境，高海拔群体受到低温和紫外线胁迫，而中海拔群体存在中国沙棘生长的适宜环境。 3. ISSR 和AFLP 分析都表明：卧龙自然保护区中国沙棘的遗传结构遵循分布范围广、交配系统以异交为主的木本植物的通常模式，即大多数的遗传变异存在于群体内，只有少部分的遗传变异存在于群体间。 4. 经Mantel 检测表明，卧龙自然保护区中国沙棘群体间的海拔距离和对应遗传距离之间存在显著的正相关关系，即随着垂直海拔距离的增加，群体间的遗传距离也随之增加。Mantel 检测结果以及聚类分析将卧龙自然保护区5 个不同海拔的中国沙棘群体分为低、中、高海拔群体三组的研究结果都表明，海拔很可能是限制群体间基因交流的主要因素。 5. ISSR 分析发现同一海拔的雌雄亚群体首先聚类的研究结果表明，同一海拔的雌雄亚群体在遗传上最相似。方差分析结果表明只有3.8%的总遗传变异存在于雌雄亚群体间，这可能与雌雄植株间的交配和遗传物质的混合有关。 6. ISSR、AFLP 和RAPD 分析都表明卧龙自然保护区不同海拔的中国沙棘天然群体的遗传多样性水平较高。它们的分析结果估算得到的Nei's 平均基因多样度(h)分别为0.249、0.214 和0.170。从该结果可以看出ISSR 和AFLP 比RAPD 检测到更多的遗传多态性,这很可能是不同标记检测的基因组的位点不同所致。 7. 依据对不同标记系统的比较分析，认为ISSR、AFLP 和RAPD 三种分子标记系统都能成功地用于调查卧龙自然保护区不同海拔的中国沙棘群体的遗传变异水平及遗传变异结构，提供关于中国沙棘天然群体多态性水平和遗传变异分布的有用信息。在三者中，AFLP 具有最高效能指数和标记指数，在确定种间分类关系或鉴别个体方面是一种比较理想的标记。 Hippophae rhamnoides subsp. sinensis, a dioecious and deciduous shrub species,occupies a wide range of habitats in the Wolong Nature Reserve, Southwest China. Ourpresent study investigated the pattern of genetic variation and differentiation among fivenatural populations of H. rhamnoides subsp. sinensis, occurring along an altitudinal gradientthat varied from 1,800 to 3,400 m above sea level in the Wolong Natural Reserve, by usingISSR and AFLP markers to guide its genetic improvement and germplasm conservation. And,comparative study of ISSR, AFLP and RAPD was performed to detect their capacity toestimating the level and pattern of genetic variation occurring among the five elevationpopulations of H. rhamnoides subsp. sinensis, and to discuss their application to the study onplant genetics. The results were list following: 1. The ISSR and AFLP analysis conducted for the H. rhamnoides subsp. sinensispopulations located in the Wolong Natural Reserve of China revealed the presence of highlevels of genetic variation (h = 0.249, HT = 0.305). Besides such features as relatively widedistribution, dominantly outcrossing mating system, and effective seed dispersal by small animals and birds, it is sometimes argued that hard climatic conditions and heterogeneous habitats may also contribute to high levels of diversity. 2. Genetic diversity of H. rhamnoides subsp. sinensis populations was found to varysignificantly with changing elevation, showing a trend that mid-elevation populations (2,200m and 2,600 m) were genetically more diverse than both low-elevation (1,800 m) andhigh-elevation populations (3,000 m and 3,400 m). H. rhamnoides subsp. sinensis is thoughtto be stressed by drought and high temperature at low elevations, and by low temperature athigh elevations. The high genetic variability present in the mid-elevation populations of H.rhamnoides subsp. sinensis is assumed to be related to a greater plant density in the middlealtitudinal zone, where favorable ecological conditions permit its continuous distributioncovering the zone from 2,200 m to 2,600 m above sea level. 3. The genetic structure of H. rhamnoides subsp. sinensis revealed by ISSRs andAFLPs followed the general pattern detected in woody species with widespread distributionsand outcrossing mating systems. Such plants possess more genetic diversity withinpopulations and less variation among populations than species with other combinations oftraits. 4. In the present study, Mantel tests showed positive correlations between altitudinaldistances and genetic distances among populations or subpopulations. The observedrelationship between altitude and genetic distances, and the result of the cluster analysisincluding populations or male subpopulations and classifying the groups into three altitudeclusters suggest that altitude is a major factor that restricts gene flow between populationsand subpopulations. 5. The analysis of molecular variance showed that only 3.8% of the variability residedbetween female and male subpopulations. Such a very restricted proportion of the totalmolecular variance between female and male subpopulations is due to common sexuality andmixing of genetic material between females and males. 6. The analysis based on ISSRs, AFLPs and RAPDs all revealed relatively high levelsof genetic variation among different altitudinal populations of H. rhamnoides subsp. sinensisin Wolong Natural Reserve of China. Their estimates of mean Nei’s gene diversity is equal to0.249, 0.214 and 0.170 respectively, suggesting the higher capacity of detecting geneticvariation of ISSR and AFLP than RAPD. It might be ascribed to their distinct sensitivity todifferent type of genetic variation. 7. Based on the coparative study on ISSR, AFLP and RAPD, we drew a conclusion thatthey all successfully reveal some useful information concerning the level and pattern ofgenetic vatiation occurring among different elevation populations of H. rhamnoides subsp.sinensis. AFLP is a ideal tool to taxonomic study and individual identification for theirhighest efficiency index and marker index among the three marker systems.

Considerable effects of diversity indices and spatial scales on conclusions relating to ecological diversity

The relationships between ecological diversity and ecosystem functions such as stability and productivity have long been debated and have no final conclusion until now. It is ignored that the debate should be firstly based on the same diversity index, which should be theoretically complete, and on same observation scale. For the issue on the scale of ecotope observation, ecosystems should be distinguished according to intensity of human disturbance. For the issue on the scale of species observation, either number diversity or biomass diversity should be identified. This paper takes grassland ecosystems located within the Bayin Xile grassland of Xilin Gol League of Inner Mongolia Autonomous Region as an example to analyze effects of different diversity indices and spatial scales on the conclusions of ecological diversity and its relationships with ecosystem functions. The analysis results both on the scale of ecotope observation and on the scale of species observation show that different diversity indices might give different conclusions and spatial resolution has a great effect on the relative conclusions. (c) 2005 Elsevier B.V. All rights reserved.

Relationship between species diversity and ecotope diversity

The relationship between species diversity and ecotope diversity has long been debated. But these debates seem meaningless because most of them were based on different definitions. In this paper, diversity has two components: richness based on the total number and evenness based on the relative abundance. Species diversity is distinguished into individual-counting diversity and biomass-based diversity. Ecotope diversity is divided into individual ecotope-counting diversity and ecotope-area based diversity. Under this definition, we make a comprehensive investigation into Dongzhi tableland of Loess Plateau by cooperating with local technicians. We find that individual-counting diversity is significantly correlated with biomass-based diversity in grassland ecosystems; individual ecotope-counting diversity and ecotope-area based diversity have a significant correlation. Therefore, it is unnecessary to divide species diversity into individual-counting diversity and biomass-based diversity in grassland ecosystems and to distinguish ecotope diversity into individual ecotope-counting and ecotope-area based diversity for the issues that have no special requirement for accuracy. But the analyses of the investigation data demonstrate that species diversity has no significant correlation with ecotope diversity.

Topological Diversity of Coordination Polymers Containing the Rigid Terephthalate and a Flexible N,N'-Type Ligand: Interpenetration, Polyrotaxane, and Polythreading

Reactions of zinc(II) or cadmium(II) salts with terephthalic acid (H(2)tp) and 1,3-bis(4-pyridyl) propane (bpp) have afforded four coordination polymers at room temperature, [Zn(mu-tp)(mu-bpp)](n)center dot 2nH(2)O (1), [Cd-2(mu-tp)(2)(mu-bpp)(3)](n)center dot 2nH(2)O (2), [Cd(mu-tp)(mu-bpp)(H2O)](n)center dot nH(2)O (3), and [Cd-2(mu-tp)(mu-bpp)(2)(bpp)(2)Br-2](n) (4). Single-crystal X-ray diffraction has revealed interesting topological features for these compounds.

Investigation of heptakis(2,6-di-O-methyl)-beta-cyclodextrin inclusion complexes with flavonoid glycosides by electrospray ionization mass spectrometry

The non-covalent complexes between three flavonoid glycosides (quercitrin, hyperoside and rutin) and heptakis(2,6-di-O-methyl)-beta-cyclodextrin (DM-beta-CD) were investigated by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS). The 1:1 complexation of each flavonoid glycoside (guest) to the DM-beta-CD (host) was monitored in the negative ion mode by mixing each guest with an up to 30-fold molar excess of the host. The binding constants for all complexes were calculated by a linear equation in the order: DM-beta-CD:quercitrin > DM-beta-CD:rutin > DM-beta-CD:hyperoside. A binding model for the complexes has also been proposed based on the binding constants and tandem mass spectrometric data of these complexes.

Structural diversity of lanthanide-amino acid complexes under near physiological pH conditions and their recognition of single-stranded DNA

We reported here four structures of lanthanide-amino acid complexes obtained under near physiological pH conditions and their individual formula can be described as [Tb-2(DL-Cys)(4)(H2O)(8)]Cl-2 (1), [Eu-4(mu(3)-OH)(4)(L-Asp)(2)(L-HAsp)(3)(H2O)(7)] Cl center dot 11.5H(2)O (2), [Eu-8-(L-HVal) (16)(H2O)(32)]Cl-24 center dot 12.5H(2)O (3), and [Tb-2(DL-HVal)(4)(H2O)(8)]Cl-6 center dot 2H(2)O (4). These complexes showed diverse structures and have shown potential application in DNA detection. We studied the interactions of the complexes with five single-stranded DNA and found different fluorescence enhancement, binding affinity and binding stoichiometry when the complexes are bound to DNA.

Evaluation of different culture conditions for high-level soluble expression of human cyclin A(2) with pET vector in BL21 (DE3) and spectroscopic characterization of its inclusion body structure

In this paper, we evaluated various parameters of culture condition affecting high-level soluble expression of human cyclin A, in Escherichia coli BL21(DE3), and demonstrated that the highest protein yield was obtained using TB(no glycerol) + 0.5% glucose medium at 25 degrees C. By single immobilized metal ion affinity chromatography, we got highly purified human cyclin A(2) with a yield ranged from 20 to 30 mg/L. By amyloid-diagnostic dye ThT binding and Fourier transform infrared spectroscopy, we observed a significant decrease in alpha-helix content and an increase in beta-sheet structure in cyclin A(2) inclusion body in comparison to its native protein, and confirmed the resemblance of the internal organization of cyclin A(2) inclusion body and amyloid fibrils.

Studies on beta-cyclodextrin amino acids inclusion complexes by electrospray ionization mass spectrometry

The positive- and negative-ion electrospray ionization mass spectra of beta-cyclodextrin-amino acids complexes in NH4Ac buffer have been reported in this paper. Compared with positive-ion ESI mass spectra of beta-cyclodextrin-amino acids complexes under the same condition, negative-ion mass spectra obtained for inclusion complexes of beta-cyclodextrin (CD) with tyrosine, phenylalanine and tryptophan, respectively, were completely dominated by deprotonated complex ions and [CD-H](-) ion which is the only daughter ion in collision-induced dissociation (CID) experiment of deprotonated complexes, The results indicated that the charged position for protonated and deprotonated complexes is different from each other. In addition, two complex ions for the same complex have similarly relative dissociation energies, which are higher than that of [CD+NH4](+), indicating that complexes observed in gasphase are not electrostatic adducts at all but complexes formed by hydrogen bonds.

Self-assembly of the pre-formed inclusion complexes between cyclodextrins and alkanethiols on gold electrodes

A new kind of self-assembled monolayer (SAM) formed in aqueous solution through the pre-formed inclusion complexes (abbreviated CD . C-n) between alpha-, beta-cyclodextrins (CDs) and alkanethiols (CH3(CH2)(n-1)SH, n = 10, 14 and 18) was prepared successfully on gold electrodes. High-resolution H-1 NMR was used to confirm the formation of CD . C-n. X-ray photoelectron spectroscopy, cyclic voltammetry and chronoamperometry were used to characterize the resulting SAMs (denoted as M-CD . Cn). It was found that M-CD . Cn were more stable against repeated potential cycling in 0.5 M H2SO4 than SAMs of CH3(CH2)(n-1)SH (denoted as M-Cn), with a relative sequence of Mbeta-CD . Cn > Malpha-CD . Cn > M-Cn. In addition, an order of blocking the electron transfer between gold electrodes and redox couples (both Fe(CN)(6)(3-) and Ru(NH3)(6)(3+)) in solution, M-CD . C10 > M-CD . C14 > M-CD . C18, was observed. A plausible explanation is provided to elucidate some of the observations. (C) 1997 Elsevier Science S.A.

Spontaneous assembly of the inclusion complexes of viologen-attached alkanethiols and alpha-, beta-cyclodestrin on gold electrode

Electroactive self-assembled monolayers (SAMs) with well-defined electrochemical responses were prepared by spontaneous assembly of the inclusion complexes (CD/C8VComegaSH) of viologen-attached alkanethiols (C8VComegaSH) and alpha- and beta-cyclodextrin (CD). They were characterized by X-ray photoelectron spectroscopy and cyclic voltammetry. The results demonstrate that the chemisorption process of CD/C8VComegaSH on gold substrate occurs through S-Au bonds, and that the redox sites in SAMs of CD/C8VComegaSH are in a much more uniform environment than those in SAMs of C8VComegaSH.