西双版纳地区流苏石斛遗传多样性的ISSR 分析

采用ISSR 分子标记技术, 对西双版纳分布的兰科濒危植物流苏石斛( Dendrobium fimbriatum) 5 个居群共114 个个体的遗传多样性进行了研究。从100 条引物中筛选出了12 条用于扩增, 共检测到117 个位点, 其中105 个为多态位点。分析结果表明, 流苏石斛居群水平遗传多样性较低。在物种水平上, 流苏石斛多态位点百分率PPB 为89 .74% , Nei′s 基因多样性指数H 为0 . 3227 , Shannon′s 多样性信息指数Hsp 为0 . 4779 ; 在居群水平上, 各个居群的多态位点百分率PPB 差异较大( 6.84% ～ 39.32% ) , 平均值为23.93% , Nei′s 基因多样性指数H 为0 . 0871 , 各个居群的Shannon′s 多样性信息指数Ho 平均为0.1290。AMOVA 分析的结果显示, 流苏石斛的遗传变异大多数存在于居群间, 占总遗传变异的74 . 79%。基于Nei′s遗传多样性分析得出的居群间遗传分化系数Gst = 0 . 7443。各居群间的Nei′s 遗传一致度( I) 范围为0 . 5882～0 . 8331。Mantel 检测发现, 居群间的遗传距离和地理距离之间无显著的正相关关系( r= 0.2419, P=0.2416) 。鉴于流苏石斛的遗传多样性现状和居群遗传结构, 我们建议对流苏石斛居群所有个体实施及时的就地保护, 同时建立迁地保护居群, 促进基因交流。     

珍稀濒危植物太行菊遗传多样性的ISSR分析

利用ISSR分子标记技术对太行山特有濒危物种太行菊11个自然居群的遗传多样性进行研究。用10个引物对11个居群的122个样品进行扩增,共得到150个扩增位点,其中多态性位点149个,多态位点百分率(PPL)为99.33%。POPGENE分析显示,太行菊具有较高的遗传多样性(H=0.2149,I=0.3455)。沁阳市大西天居群的遗传多样性水平最高(H=0.1910,I=0.2969),山西陵川县大双村居群的遗传多样性水平最低(H=0.1356,I=0.2155)。Nei’s遗传多样性分析表明,11个自然居群间出现了较高的遗传分化(基因分化系数Gst=0.2566,基因流Nm=1.4488)。生境的的片段化和基因流障碍可能是导致太行菊居群间遗传分化显著的主要原因。通过对太行菊居群遗传多样性和遗传结构的分析,该文提出了一些保护策略。     

8个山荆子居群遗传多样性的ISSR分析

采用ISSR标记对中国北方地区的8个山荆子居群进行了遗传多样性分析,以探讨山荆子在苹果属植物演化过程中的作用.结果显示:(1)从55个ISSR引物中,筛选出11个多态性引物,共扩增出71个位点,其中多态性位点69个,多态位点达97.47%.(2)在物种水平上,有效等位基因数Ne=1.467 0,Nei's基因多样性(H)为0.284 6,Shannon信息指数(I)为0.439 9,多态位点百分率(PPB)=80.22;基因流(Nm)为1.659 1,居群间基因分化系数(Gst)为0.231 6,Φst值为0.236 0.(3)聚类分析结果显示,在遗传距离为0.155 5、0.136 9、0.125 8处8个山荆子居群分别聚为两大类、三亚类、四小类,但居群聚类位置与地理位置无明显的相关性.(4)山荆子的居群内遗传多样性贡献率占76.40%,而居群间的贡献率占23.60%,说明山荆子的遗传多样性主要分布在居群内,但居群间的遗传分化程度也较高.由此推测,山荆子的起源中心在华北和东北范围内,其中灵空山(山西)和塞罕坝(河北)居群可近似为核心居群;ISSR标记与花部的一些性状可能有连锁关系.     

三峡库区特有种疏花水柏枝的保护遗传学研究

采用超薄平板微型聚丙烯酰胺等电聚焦电泳方法对三峡库区特有种疏花水柏枝 (Myricarialaxiflora)的 13个自然居群和 1个人工迁地保护居群的等位酶遗传变异进行了初步研究。检测了 5个酶系统 ,得到 13个等位酶位点 ,遗传多样性及其遗传结构分析结果表明 :疏花水柏枝具有较高水平的遗传多样性 ,平均多态位点比率P =78.7% ,每位点平均等位基因数A =1.8,平均预期杂合度He=0 .317,高于中国植物特有种的平均水平 ,且群体中杂合基因型个体偏多 ;其遗传变异主要发生于居群内 ( 84.86 % ) ,居群间又存在一定的遗传分化 (Gst=0 .15 14) ,居群间平均基因流Nm =1.40 1,居群间遗传距离为 0 .0 0 2～ 0 .176 ;UPGMA聚类分析显示疏花水柏枝在三峡湖北境内的白水河—泄滩一带分为上游和下游 2个居群组 ;武汉植物园迁地保护的混合居群基本保育了其遗传多样性总水平。在分析讨论疏花水柏枝遗传多样性与其繁育系统、生境及其起源进化的关系的基础上 ,探讨了疏花水柏枝濒危的主要原因 ,推断其应为第四纪冰期影响后的古孑遗种。最后 ,在评价迁地保护成果的基础上 ,提出了今后进一步保育的策略。     

利用ISSR标记对新疆梭梭遗传多样性的研究

利用ISSR分子标记对新疆梭梭8个居群、218个个体进行了遗传多样性的比较分析,在供试材料中,11个引物共扩增出222个多态位点,多态位点百分率为89.23%,8个居群的多态位点百分率差异在23.42%~45.05%之间,多态位点百分率最高的是乌苏居群,最低的为托克逊居群.遗传变异分析表明,物种水平的基因分化系数Gst为63.78.居群间的基因流Nm为0.284 0,Shannon多样性指数(I)为0.506 0,物种水平的Nei s基因多样度(H)为0.336 2.遗传分析表明乌苏居群和莫索湾居群有较近的遗传距离.     

湖北海棠的等位酶变异和遗传多样性研究

采用超薄平板微型聚丙烯酰胺等电聚焦电泳方法对湖北海棠（Malus hupehensis)的9个野生居群和2个人工栽培居群的等位酶变异和遗传多样性进行了初步研究。通过对12个酶系统29个酶位点的检测,结果表明湖北海棠有25个酶位点的等位基因频率分布差异,,有10个居群发现稀有等位基因,并有11个（37．9％）重复位点;湖北海棠的遗传多样性水平很高,等位基因平均数A＝2．127,多态位点百分率P＝74．927,平均预期杂合度He=0.376;居群间的基因分化系数GST＝0．224。与其他苹果属植物相比,湖北海棠具有中等丰富的遗传变异水平。居群间的基因流仅为Nm=0.866,表明遗传漂变是影响居群遗传变异和遗传结构的一个重要因素。     

濒危植物版纳青梅保护遗传学研究初报

运用 2 0个 10碱基随机引物 ,对中国龙脑香科 (Dipterocarpaceae)特有的珍稀濒危植物版纳青梅 (VaticaguangxiensisX .L .Mo)进行了RAPD多态性分析。 3个自然居群和 1个迁地保护居群 (分布于云南和广西 )共扩增出2 31个位点 ,多态位点所占比例 (PPB)为 5 3.6 8% ;观察等位基因数na =1.5 36 8,有效等位基因数ne =1.2 878,Nei基因多样性指数h为 0 .16 86 ,居群内的遗传多样性水平较低。基于AMOVA和POPGENE的结果均表明居群内的遗传变异大于居群间的遗传变异。居群内的遗传变异为 5 5 .0 9% ,居群间的变异为 44 .91% (AMOVA) ;基因分化系数Gst为 0 .3746 (POPGENE) ,表明居群间存在高水平的遗传分化。研究结果对该濒危植物的保护有重要意义。考虑到低水平的遗传多样性和高水平的居群分化 ,通过居群间种子和幼苗的交换来促进基因流是可行的保护方案。迁地保护居群 (ML)不具最高的遗传多样性 ,表明为了保护此濒危物种的全部遗传变异 ,需要进一步采集更多个体补充到迁地保护居群中     

樟科濒危植物思茅木姜子遗传多样性的ISSR分析

本文采用ISSR标记对中国特有且仅在云南南部狭域分布的樟科濒危植物思茅木姜子(Litseaszemaois)现存8个居群的遗传多样性进行了研究。从96条引物中筛选出了10条,对103个个体进行了扩增,共扩增出77条条带,其中多态性条带为67条。分析结果表明:(1)思茅木姜子的遗传多样性水平很高。在物种水平上,多态位点百分率PPB=87.01%,平均每个位点的有效等位基因数Ne=1.4006,Nei’s基因多样度指数H=0.2466,Shannon多样性信息指数Hsp=0.3826;在居群水平上,PPB=37.99%,Ne=1.2500,H=0.1418,Shannon多样性信息指数Hpop=0.2088。(2)居群间的遗传分化较低。基于Nei’s遗传多样性分析得出的居群间遗传分化系数Gst=0.3700;Shannon’s居群分化系数((Hsp–Hpop)/Hsp)为0.45。AMOVA分析显示:思茅木姜子的遗传变异主要存在于居群内,占总变异的72.99%,居群间的遗传变异占27.01%,表明思茅木姜子属于异交种。(3)两两居群间的Nei’s遗传一致度(I)的范围为0.8233–0.9761。经Mantel检测,居群间的遗传距离和地理距离之间不存在显著的正相关关系(r=0.0925,P=0.6931)。我们推断人类活动的干扰和生境的片断化是导致思茅木姜子濒危现状的主要因素。考虑到目前其遗传多样性水平虽然很高,但各居群个体数量很少,因此应该对思茅木姜子各居群的所有个体实施及时的就地保护;而遗传变异大部分存在于居群内的个体间,所以在迁地保护时应在各居群内大量采样。     

云南灯盏花遗传变异的RAPD分析

运用RAPD (randomamplifiedpolymorphicDNA)技术对云南灯盏花 (Erigeronbrevis capus) 6个居群进行分析 ,研究其遗传变异及遗传结构 ,用外类群紫菀对比分析其亲缘关系。随机挑选 16个引物在 6个居群中共产生 2 33条DNA片段 ,其中 192条带具有遗传多态性 ,约占 82 4 0 %。多态位点百分比PPB、等位基因数A、有效等位基因数Ae、Nei’s基因多样性指数H和Shannon多样性指数I在物种水平分别为 82 4 0 %、 1 82 4 0、 1 30 0 5、0 1896、 0 30 2 1;居群的平均值分别为 5 4 2 3%、 1 5 40 1、 1 2 6 91、 0 16 0 7、 0 2 4 6 0。灯盏花的遗传多样性较丰富 ,基因分化系数Gst值为 0 346 0 ,有 6 5 4 0 %的变异来自居群内 ,6个居群的遗传一致度较高 ,在 0 90 37～ 0 972 3之间 ,平均为 0 94 10。利用UPGMA对 6居群聚类分析 ,结果表明 :丘北居群 (YB)和文山居群 (YX)亲缘关系最近 ,小哨居群 (Y )和新平居群 (YA)次之 ,丘北居群 (YB)和腾冲居群 (ZA)亲缘关系最远。遗传关系与各居群地理分布区间的距离大致成正相关     

葫芦苏铁遗传多样性的等位酶分析

采用等位酶技术,分析了葫芦苏铁5个居群的遗传多样性。分析6个酶系统,共获得了13个基因位点, 结果表明:葫芦苏铁具有较高水平的遗传变异性,多态位点百分率(P)为56．9％,等位基因平均数A=1.62,等 位基因多样性指数Ho=0.105,He=0．164,居群杂合体过量的位点为50％。居群遗传结构分析表明,大部分 遗传变异(93．6％)存在于居群内(FST=0．064),居群间分化程度甚微。根据葫芦苏铁的居群遗传结构式样并 结合相关研究,提出了就地保护所有居群,迁地保护从东一、王下和水田三个大居群取样的保护策略。     

Metabolic rates,genetic constraints,and the evolution of endothermy

The metabolic distinction between endotherms and ectotherms is profound. Whereas the ecology of metabolic rates is well studied, how endotherms evolved from their ectothermic ancestors remains unclear. The aerobic capacity model postulates that a genetic constraint between resting and maximal metabolism was essential for the evolution of endothermy. Using the multivariate breeders’ equation, I illustrate how the (i) relative sizes of genetic variances and (ii) relative magnitudes of selection gradients for resting and maximal metabolism affect the genetic correlation needed for endothermy to have evolved via a correlated response to selection. If genetic variances in existing populations are representative of ancestral conditions, then the aerobic capacity model is viable even if the genetic correlation was modest. The analyses reveal how contemporary data on selection and genetic architecture can be used to test hypotheses about the evolution of endothermy, and they show the benefits of explicitly linking physiology and quantitative genetic theory.     

THE ACTION OF STABILIZING SELECTION,MUTATION, AND DRIFT ON EPISTATIC QUANTITATIVE TRAITS

For a quantitative trait under stabilizing selection, the effect of epistasis on its genetic architecture and on the changes of genetic variance caused by bottlenecking were investigated using theory and simulation. Assuming empirical estimates of the rate and effects of mutations and the intensity of selection, we assessed the impact of two‐locus epistasis (synergistic/antagonistic) among linked or unlinked loci on the distribution of effects and frequencies of segregating loci in populations at the mutation‐selection‐drift balance. Strong pervasive epistasis did not modify substantially the genetic properties of the trait and, therefore, the most likely explanation for the low amount of variation usually accounted by the loci detected in genome‐wide association analyses is that many causal loci will pass undetected. We investigated the impact of epistasis on the changes in genetic variance components when large populations were subjected to successive bottlenecks of different sizes, considering the action of genetic drift, operating singly (D), or jointly with mutation (MD) and selection (MSD). An initial increase of the different components of the genetic variance, as well as a dramatic acceleration of the between‐line divergence, were always associated with synergistic epistasis but were strongly constrained by selection.     

基因甘蔗：潜能、现状和前景

从基因中在甘蔗上的应用潜能、甘蔗遗传转化的方法及其成效、启动子及选择标记对基因表达和转化体筛选的效应,基因工程甘蔗的成就等几个方面进行综述评述,并提出了进一步的研究方向。     

Reassessing insurers' access to genetic information: genetic privacy, ignorance, and injustice

Many countries have imposed strict regulations on the genetic information to which insurers have access. Commentators have warned against the emerging body of legislation for different reasons. This paper demonstrates that, when confronted with the argument that genetic information should be available to insurers for health insurance underwriting purposes, one should avoid appeals to rights of genetic privacy and genetic ignorance. The principle of equality of opportunity may nevertheless warrant restrictions. A choice-based account of this principle implies that it is unfair to hold people responsible for the consequences of the genetic lottery, since we have no choice in selecting our genotype or the expression of it. However appealing, this view does not take us all the way to an adequate justification of inaccessibility of genetic information. A contractarian account, suggesting that health is a condition of opportunity and that healthcare is an essential good, seems more promising. I conclude that if or when predictive medical tests (such as genetic tests) are developed with significant actuarial value, individuals have less reason to accept as fair institutions that limit access to healthcare on the grounds of risk status. Given the assumption that a division of risk pools in accordance with a rough estimate of people's level of (genetic) risk will occur, fairness and justice favour universal health insurance based on solidarity.     

Invasiveness,chimerism and genetic diversity

Adaptation for invasiveness should comprise the capability to exploit and prosper in a wide range of ecological conditions and is therefore expected to be associated with a certain level of genetic diversity. Paradoxically, however, invasive populations are established by only a few founders, resulting in low genetic diversity. As a conceivable way of attaining high genetic diversity and high variance of gene expression even when a small number of founders is involved in invasiveness, I suggest here chimerism, a fusion between different individuals—a common phenomenon found in numerous phyla. The composite entity offers the chimeric organism genetic flexibility and higher inclusive fitness that depends on the joint genomic fitness of the original partners. The ability to form a chimeric entity is also applied to subsequent generations, and consequently, the level of genetic diversity does not decline over generations of population establishment following invasion.     

应用STS-PCR标记研究新疆布顿大麦的遗传多样性

利用22个来源于小麦(Triticum aestivum L.)和栽培大麦(Hordeum vulgare L.)的STS-PCR标记,研究了32份新疆布顿大麦(Hordeum bogdanii Wilensky)的遗传多样性.在这22个STS-PCR标记中,仅有3个标记的扩增产物经HinfⅠ、HhaⅠ、HaeⅢ和RsaⅠ 4种限制性内切酶消化后没有产生多态性DNA片段,而19个标记(占86.4%)和46种标记/酶组合(占52.3%)能够揭示材料间的多态性.在32份布顿大麦材料的88种STS-PCR标记/酶组合中,总共得到315条DNA片段,平均每个标记/酶组合能得到3.6条DNA片段.在这315条DNA片段中,共有123条片段(占39.0%)具有多态性,每一个多态性标记/酶组合能获得1～6条多态性DNA片段.STS-PCR标记揭示的32份布顿大麦的遗传距离变化范围为0.078～0.352,平均为0.198.根据STS-PCR标记的遗传距离矩阵,采用不完全加权算术平均数法(UPGMA)构建了32份布顿大麦群体间的遗传关系树状图,结果表明STS-PCR标记能将32份材料完全区分开来.同时,来源于同一地方的不同居群没有明显地聚类在一起,表明新疆布顿大麦的遗传多样性与其地理分布相关不紧密.     

Genetic relationships between feral cattle from Chirikof Island, Alaska and other breeds

The origin of cattle on Chirikof Island, off the coast of Alaska, is not well documented. We assessed genetic differentiation of cattle isolated on Chirikof Island from several breeds commonly used for commercial production in North America including breeds popularly believed to have contributed to the Chirikof Island population. A set of 34 microsatellite loci was used to genotype Angus, Charolais, Hereford, Highland, Limousin, Red Angus, Salers, Shorthorn, Simmental, Tarentaise and Texas Longhorn cattle sampled from North America and the Chirikof Island population. Resulting F(ST) statistics for these loci ranged from 0.06 to 0.22 and on average, 14% of total genetic variation was between breeds. Whether population structure was modelled as a bifurcating tree or genetic network, Chirikof Island cattle appeared to be unique and strongly differentiated relative to the other breeds that were sampled. Bayesian clustering for multiple-locus assignment to genetic groups indicated low levels of admixture in the Chirikof Island population. Thus, the Chirikof Island population may be a novel genetic resource of some importance for conservation and industry.     

应用STS—PCR标记研究新疆布顿大麦的遗传多样性

利用 2 2个来源于小麦 (TriticumaestivumL .)和栽培大麦 (HordeumvulgareL .)的STS_PCR标记 ,研究了 32份新疆布顿大麦 (HordeumbogdaniiWilensky)的遗传多样性。在这 2 2个STS_PCR标记中 ,仅有 3个标记的扩增产物经HinfⅠ、HhaⅠ、HaeⅢ和RsaⅠ 4种限制性内切酶消化后没有产生多态性DNA片段 ,而 19个标记 (占 86 .4 % )和 4 6种标记 /酶组合 (占 5 2 .3% )能够揭示材料间的多态性。在 32份布顿大麦材料的 88种STS_PCR标记 /酶组合中 ,总共得到 315条DNA片段 ,平均每个标记 /酶组合能得到 3.6条DNA片段。在这 315条DNA片段中 ,共有 12 3条片段(占 39.0 % )具有多态性 ,每一个多态性标记 /酶组合能获得 1～ 6条多态性DNA片段。STS_PCR标记揭示的 32份布顿大麦的遗传距离变化范围为 0 .0 78～ 0 .35 2 ,平均为 0 .198。根据STS_PCR标记的遗传距离矩阵 ,采用不完全加权算术平均数法 (UPGMA)构建了 32份布顿大麦群体间的遗传关系树状图 ,结果表明STS_PCR标记能将 32份材料完全区分开来。同时 ,来源于同一地方的不同居群没有明显地聚类在一起 ,表明新疆布顿大麦的遗传多样性与其地理分布相关不紧密。     

广东省中山市五桂山土沉香遗传多样性

土沉香(Aquilaria sinensis)是生产中药沉香的重要树种,现被列为国家二级重点保护野生植物。该研究通过采集该地区83株土沉香样品,利用限制性酶切位点相关DNA测序(restriction site-associated DNA sequencing,RAD-seq)方法获得的18个微卫星体作为分子标记,计算了五桂山土沉香种群的整体观测杂合度(observed-heterozygosity)、期望杂合度(expected-heterozygosity)、种群整体近交系数及其个体间的亲缘关系,并对种群可能经历的种群缩小或种群扩张状况进行了分析。结果表明:与同属其它物种以及同一生活史物种相比,五桂山地区土沉香遗传多样性略低(观测杂合度和期望杂合度分别为0.523和0.522),但种群整体处于随机交配状态(近交系数为-0.002)。瓶颈效应分析表明该种群没有经历瓶颈效应,且81.810%的个体间无亲缘关系,说明这一地区土沉香并非少数个体发育起来;种群扩张分析表明其种群大小有增长情形。综合这些结果可以看出,中山市五桂山土沉香种群整体遗传健康状况良好,较好地保存了该区域种质资源遗传多样性,为今后的保护和合理开发提供了优质资源储备。