沙冬青属的细胞学研究

沙冬青属(Ammopiptanthus)植物仅两个种,即蒙古沙冬青(A.mongolicus)和新疆沙冬青(A.nanus),为第三纪残遗种,是中亚荒漠唯一的常绿阔叶植物,因珍稀,临危而被列为国家重点保护植物”。国内外对该属两个种的染色体数目的记载存在着差异。本文对沙冬青属两种植物的染色体数目和核型进行了分析研究,旨在为探讨该属植物的发生和系统发育,以及开展植物多样性保护和合理开发利用积累资料。     

荒漠珍品—沙冬青

沙冬青 (ＡｍｍｏｐｉｐｔａｎｔｕｓｍｏｎｇｌｉｃｕｓＭａｘｉｍ .ｅｘＫｏｍ)又名蒙古沙冬青、蒙古黄花木 ,属蝶形花科沙冬青属。常绿灌木 ,高约 2ｍ ,冠幅 3ｍ ,掌状三小叶 ,稀单叶。总状花序 ,有花 8～ 10 ,花黄色。果扁平 ,长圆形 ,长 5～ 8ｃｍ ,宽 1.6～ 2ｃｍ ,种子 2～ 5 ,圆肾形 ,花期 4月 ,果期 5月。1　分布现状沙冬青为古老的常绿残遗植物 ,是干旱荒漠区唯一的常绿沙旱生灌木 ,为阿拉善戈壁荒漠的特有种 ,国家三级保护植物。成片或间断分布于东经 97 ～ 10 7 北纬 37 ～ 4 2 的荒漠 ,半荒漠地带 ,在甘肃河西走廊分布有 2 6 …     

一种有效分离沙冬青线粒体基因组DNA的方法

线粒体作为重要的细胞器,在植物进化适应过程中起着不可忽视的作用。抗旱耐寒常绿阔叶灌木沙冬青主要分布在我国西北荒漠地区,是第三纪孑遗植物,研究该植物线粒体基因组与长期进化适应的关系具有重要意义。然而,用常规的方法难以分离纯化获得沙冬青线粒体基因组DNA,限制了沙冬青线粒体功能基因组研究。该研究利用不连续蔗糖梯度密度离心和DNase I消化技术,成功获得了高纯度沙冬青线粒体DNA,该线粒体DNA的纯度和完整性满足建库的要求,为沙冬青线粒体基因组研究提供了技术支持,对其他植物线粒体基因组学研究也具有参考价值。     

逆境中沙冬青叶片细胞叶绿体的结构(简报)

沙冬青(Ammopiptanthus mongolicus)是亚洲中部一种超旱生植物,生长在荒漠、半荒漠地带,主要分布于我国内蒙古、宁夏、甘肃等地,是北方地区极少有的常绿阔叶植物,也是国家二级保护植物。沙冬青体内含有黄花木素、拟黄花木素等强生物碱,是重要的药用植物,也是极好的固沙、绿化荒丘植物。它耐热、旱、盐碱,更耐寒,能抵抗-30℃至-40℃的低温,所以也是植物抗逆性研究的理想材料。     

濒危植物小沙冬青研究进展

小沙冬青(Ammopiptanthus nanus (M. Pop.) Cheng f.)是荒漠干旱极端环境下唯一的常绿阔叶灌木,也是抗逆性研究的优秀指示植物材料。本文在查阅文献的基础上,对小沙冬青的群落生态学、解剖学、生殖生态学及遗传多样性、逆境胁迫下小沙冬青的生理及分子生物学响应方面的研究进行了综述,旨在为该植物资源的开发利用、荒漠区物种多样性的维持和生态环境建设提供借鉴。     

沙冬青及其伴生植物深色有隔内生真菌物种多样性

2013年7月从内蒙古磴口,宁夏银川、沙坡头和甘肃民勤采集沙蒿(Artemisia desertorum)、红花锦鸡儿(Caragana rosea)、白刺(Nitraria tangutorum)、柠条锦鸡儿(Caragana korshinskii)等4种沙冬青(Ammopiptanthus mongolicus)伴生植物的根系样品,采用形态特征结合r DNA ITS序列分析进行真菌分类鉴定,研究了深色有隔内生真菌(DSE)群落组成和物种多样性。从4种伴生植物根样中共分离鉴定7类DSE(即Alternaria、Curvularia、Embellisia、Phialocephala、Phoma、Podospora和Pleosporales),其中Alternaria、Embellisia、Curvularia和Podospora为荒漠生态系统首次报道的DSE。同一样地伴生植物与沙冬青DSE群落组成差异明显,不同样地沙冬青与伴生植物DSE物种多样性指数差异显著。结果表明,自然条件下沙冬青DSE定殖率和物种数量,特别是产孢种类和数量多于其伴生植物,暗示DSE能够与沙冬青根系形成更好的共生关系,增强沙冬青对极端荒漠环境的生态适应性。     

沙冬青逆境胁迫分子生物学研究进展

逆境胁迫是影响植物生长发育的重要因素,植物的抗逆机理是分子生物学研究的重要领域。随着分子生物学技术的发展,有关植物抗逆方面的研究已取得了很大的进展,初步揭示了植物应对逆境胁迫适应性的分子机理。沙冬青是我国温带荒漠地区惟一的常绿灌木,具有很强的抗逆性,是开展植物逆境胁迫研究和抗逆基因筛选的理想材料。本文综合论述了抗逆植物沙冬青的抗逆机理及逆境胁迫相关基因的分子生物学研究进展,为植物抗逆基因工程发掘更多的基因资源和抗旱植物的抗逆性研究提供思路。     

内蒙古高原的豆科植物

在我国内蒙古高原的沙漠地区,植被类型是荒漠和草原,其中各种豆科植物在构成这类植被中起着十分重要的作用,因为这些植物根部共生的根瘤菌能固定空气中的氮元素,从而使土壤贫瘠的沙漠和沙地获得自然氮素的来源。本文将在该地区常见的几种豆科植物逐一简介如下:(1)沙冬青(Ammopiptanthusmongolicus),在亚洲中部沙漠地区唯一现存的特有常绿灌木,我国的内蒙古西部、甘肃中北部、宁夏的北部地区,以及蒙古国荒漠带南端的阿拉善戈壁均有分布。沙冬青超旱生常绿灌木,高1—1.6米, 在沙砾质荒漠中常成为优势种,有时为伴生种。分布在沙质、沙砾质高原…     

沙冬青属植物花期生物学特性研究

沙冬青,为豆科强度旱生常绿灌木,沙质及沙砾质荒漠建群植物,仅两种。在亚洲中部旱生植物区系中属第三世残遗种。其花大、色艳,花期较长,衬之以绿色的植丛,在早春光秃的荒漠景观中尤为引人注目,是颇具观赏价值的野生花灌木资源。     

生长素和氯化钙对盐胁迫下沙冬青幼苗的缓解作用

沙冬青(Ammopiptanthus mongolicus)是亚洲中部荒漠地区唯一的常绿阔叶灌木,本课题组已将其在天津引种栽培成功。为进一步了解生长素和氯化钙对沙冬青在盐胁迫下的缓解作用,用水培方法培养沙冬青幼苗,测定其在1.3%NaCl胁迫下经不同浓度的生长素和氯化钙处理后抗氧化酶活性、PSII光化学效率以及其它与植物抗性有关的生理指标的变化。结果表明,一定浓度的IBA和CaCl2处理可以促进盐胁迫下沙冬青幼苗的生长、提高叶绿素的含量、增强保护酶的活性、降低丙二醛含量,缓解了盐胁迫。但是当IBA、CaCl2浓度分别达到5和20mmol.L-1时则对沙冬青幼苗产生伤害。综合各项生理指标说明,CaCl对沙冬青盐胁迫的缓减作用要优于IBA。     

Forensic characteristic and population structure dissection of Shaanxi Han population in the light of diallelic deletion/insertion polymorphism data

The genetic polymorphisms of diallelic deletion/insertion polymorphic (DIP) loci in the Shaanxi Han population are still not clearly characterized. Herein, allele frequencies and forensic application efficiencies for 30 diallelic DIP loci were investigated in 506 unrelated healthy Han individuals from Chinese Shaanxi province. Based on population data of the same 30 diallelic DIP loci, the genetic differentiations, hierarchical clustering relationships and population architectures among Shaanxi Han and other 50 populations were further dissected through genetic and bioinformatics analyses. Results indicated that most of the 30 diallelic DIP loci were relatively high polymorphisms in the Shaanxi Han population; and there were the genetically intimate relationships between Shaanxi Han and the East Asian populations. In summary, this study provided significant insights into genetic background of Shaanxi Han population, and the multiplex amplification of these 30 diallelic DIP loci was appropriate for forensic individual identification and population genetic research in Shaanxi Han population.     

Estimating true prevalence of Schistosoma mansoni from population summary measures based on the Kato-Katz diagnostic technique

BackgroundThe prevalence of Schistosoma mansoni infection is usually assessed by the Kato-Katz diagnostic technique. However, Kato-Katz thick smears have low sensitivity, especially for light infections. Egg count models fitted on individual level data can adjust for the infection intensity-dependent sensitivity and estimate the ‘true’ prevalence in a population. However, application of these models is complex and there is a need for adjustments that can be done without modeling expertise. This study provides estimates of the ‘true’ S. mansoni prevalence from population summary measures of observed prevalence and infection intensity using extensive simulations parametrized with data from different settings in sub-Saharan Africa.MethodologyAn individual-level egg count model was applied to Kato-Katz data to determine the S. mansoni infection intensity-dependent sensitivity for various sampling schemes. Observations in populations with varying forces of transmission were simulated, using standard assumptions about the distribution of worms and their mating behavior. Summary measures such as the geometric mean infection, arithmetic mean infection, and the observed prevalence of the simulations were calculated, and parametric statistical models fitted to the summary measures for each sampling scheme. For validation, the simulation-based estimates are compared with an observational dataset not used to inform the simulation.Principal findingsOverall, the sensitivity of Kato-Katz in a population varies according to the mean infection intensity. Using a parametric model, which takes into account different sampling schemes varying from single Kato-Katz to triplicate slides over three days, both geometric and arithmetic mean infection intensities improve estimation of sensitivity. The relation between observed and ‘true’ prevalence is remarkably linear and triplicate slides per day on three consecutive days ensure close to perfect sensitivity.Conclusions/significanceEstimation of ‘true’ S. mansoni prevalence is improved when taking into account geometric or arithmetic mean infection intensity in a population. We supply parametric functions and corresponding estimates of their parameters to calculate the ‘true’ prevalence for sampling schemes up to 3 days with triplicate Kato-Katz thick smears per day that allow estimation of the ‘true’ prevalence.     

Estimation in Longitudinal or Panel Data Models with Random‐Effect‐Based Missing Responses

Summary In studies with longitudinal or panel data, missing responses often depend on values of responses through a subject‐level unobserved random effect. Besides the likelihood approach based on parametric models, there exists a semiparametric method, the approximate conditional model (ACM) approach, which relies on the availability of a summary statistic and a linear or polynomial approximation to some random effects. However, two important issues must be addressed in applying ACM. The first is how to find a summary statistic and the second is how to estimate the parameters in the original model using estimates of parameters in ACM. Our study is to address these two issues. For the first issue, we derive summary statistics under various situations. For the second issue, we propose to use a grouping method, instead of linear or polynomial approximation to random effects. Because the grouping method is a moment‐based approach, the conditions we assumed in deriving summary statistics are weaker than the existing ones in the literature. When the derived summary statistic is continuous, we propose to use a classification tree method to obtain an approximate summary statistic for grouping. Some simulation results are presented to study the finite sample performance of the proposed method. An application is illustrated using data from the study of Modification of Diet in Renal Disease.     

Association of rs4552569 and rs17095830 single-nucleotide polymorphisms with susceptibility to ankylosing spondylitis in east Asian population: a meta-analysis

Several studies have been conducted in east Asian population to evaluate the association between rs4552569 and rs17095830 single-nucleotide polymorphisms (SNPs) with susceptibility to ankylosing spondylitis (AS), but the outcomes are inconsistent. A summary evaluation of the evidence supporting the associations has not been performed. Therefore, we performed this meta-analysis to access whether the two SNPs are related to ankylosing spondylitis. We systematically searched PubMed, EMBASE, Web of Science and Cochrane Library for papers published up until 3 February 2017, to obtain relevant studies using our research strategy. The allele/genotype frequencies were extracted from each study. We calculated the summary odds ratios (ORs) and 95% confidence intervals (CIs) to evaluate the associations between the two SNPs and AS risk. Four papers including five studies were obtained for this meta-analysis. The included studies suggested that there was no significant association between rs4552569 SNP and AS (C vs T, OR = 1.08, 95% CI: 0.96–1.22, P = 0.20). With regard to rs17095830 SNP, significant association was observed (G vs A, OR = 1.19, 95% CI: 1.06–1.33, P = 0.002). Based on a comprehensive analysis of the currently available evidence, rs4552569 SNP is not significantly associated with the predisposition of AS, while rs17095830 SNP is likely a susceptibility variant for AS in east Asian population. Further studies with different population groups are needed to confirm these potential associations.     

L—色氨酸的生产及其代谢控制育种

本综述了利用微生物生产Ｌ－色氨酸的各种方法和Ｌ－色氨酸的生物合成途径及其代谢调控机制,并介绍了利用重组ＤＮＡ技术选育Ｌ－色氨酸高产菌的研究现状。     

Population Graphs: the graph theoretic shape of genetic structure

Patterns of intraspecific genetic variation result from interactions among both historical and contemporary evolutionary processes. Traditionally, population geneticists have used methods such as F-statistics, pairwise isolation by distance models, spatial autocorrelation and coalescent models to analyse this variation and to gain insight about causal evolutionary processes. Here we introduce a novel approach (Population Graphs) that focuses on the analysis of marker-based population genetic data within a graph theoretic framework. This method can be used to estimate traditional population genetic summary statistics, but its primary focus is on characterizing the complex topology resulting from historical and contemporary genetic interactions among populations. We introduce the application of Population Graphs by examining the range-wide population genetic structure of a Sonoran Desert cactus (Lophocereus schottii). With this data set, we evaluate hypotheses regarding historical vicariance, isolation by distance, population-level assignment and the importance of specific populations to species-wide genetic connectivity. We close by discussing the applicability of Population Graphs for addressing a wide range of population genetic and phylogeographical problems.     

Approximate Bayesian computation in population genetics

We propose a new method for approximate Bayesian statistical inference on the basis of summary statistics. The method is suited to complex problems that arise in population genetics, extending ideas developed in this setting by earlier authors. Properties of the posterior distribution of a parameter, such as its mean or density curve, are approximated without explicit likelihood calculations. This is achieved by fitting a local-linear regression of simulated parameter values on simulated summary statistics, and then substituting the observed summary statistics into the regression equation. The method combines many of the advantages of Bayesian statistical inference with the computational efficiency of methods based on summary statistics. A key advantage of the method is that the nuisance parameters are automatically integrated out in the simulation step, so that the large numbers of nuisance parameters that arise in population genetics problems can be handled without difficulty. Simulation results indicate computational and statistical efficiency that compares favorably with those of alternative methods previously proposed in the literature. We also compare the relative efficiency of inferences obtained using methods based on summary statistics with those obtained directly from the data using MCMC.     

中国特有两栖类受胁现状分析

中国拥有丰富的两栖类资源,共321种,其中特有种236种,这些特有种是我国生物资源独特而重要的组成部分.但受人为和自然等因素的影响,中国特有两栖类出现了较快的种群数量下降,部分物种已经面临濒危状况而很少被人们关注.本文将对中国特有两栖类的数量、分布、受胁原因作简要阐述,以制定相应的保护对策.     

核糖体DNA ITS区序列在植物分子系统学研究中的价值

本文就近年来国内外有关被子植物核糖体ＤＮＡ中的内转录间隔区（ＩＴＳ）序列在植物属内,近缘属间乃至科内系统发育研究中的应用,结合作者在中国姜科山姜属（Ａｌｐｉｎｉａ Ｒｏｘｂ．）上的研究,对ＩＴＳ区序列在植物分子系统学研究中的价值作一简要综述,对其应用前景也进行了讨论。