查询词典 gene flow

During the postgenomics era the information about genomic sequence and gene functions provides a new foundation for evolutionary biology and ecology As the first whole-genome sequenced plant Arabidopsis thaliana and its wild relatives have played a critical role in understanding the evolution of genomics and speciation Both A halleri and A lyrata are closely related to the model species A thaliana A halleri ssp gemmifera occurs in northeastern China Japan and Taiwan; while its sister A halleri ssp halleri is mainly distributed in Europe Geographical barriers such as Tienshan Mountain Range isolate these intraspecific sisters Likewise A lyrata ssp kamchatica and ssp lyrata occur in East Asia and North America respectively Such distribution patterns seem to be consistent with allopartic speciation The comparison between ancestral and extant polymorphism by multilocus can be informative about the population genetics of speciation In this study we collected and analyzed DNA sequences of 98 genes from four wild relatives of A thaliana A halleri ssp gemmifera A halleri ssp halleri A lyrata ssp kamchatica and A lyrata ssp lyrata The ancestral states of these four species were compared to each other in terms of level of genetic variation However the ancestral species at the time of speciation were substantially more polymorphic than the extant geographical populations The observations are not fully compatible with speciation by strict allopatry At some species pairs parapatric speciation seems more reasonable in speciation of Arabidopsis The 98 gene sequences are also used for the congruence test between gene genealogy and species phylogeny Only 28 genes support the species phylogeny but there are 23 genes supports another major genealogy { lyrata} thaliana Based on the phylogenetic position change of A lyrata ssp kamchatica and Ks value for each species pair suggested the recent directional gene flow between A halleri ssp gemmifera and A lyrata ssp kamchatica

阿拉伯芥是第一个完成基因体定序的开花植物，其基因体资讯提供植物学研究的重要依据；在解析阿拉伯芥属物种的亲缘关系以及种化机制等重要的演化议题时，阿拉伯芥近缘的野生物种自然成了不可或缺的关键；跟阿拉伯芥近缘的物种包括A halleri及A lyrata，其中A halleri ssp gemmifera主要分布於中国东北、日本以及台湾，与近缘的A halleri ssp halleri其分布於欧洲隔著天山及大陆的障蔽，而A lyrata ssp kamchatica主要分布於东北亚及台湾，与分布於北美五大湖的A lyrata ssp lyrata被北极圈所分隔，这样的分布模式暗示异域种化的可能。藉由多基因分析比较祖先物种与现生物种遗传歧异度的相关可提供讯息探讨种化时期的族群遗传结构，本研究针对A halleri ssp gemmifera、A halleri ssp halleri及A lyrata ssp kamchatica、A lyrata ssp lyrata四个物种，两对互为亚种的姊妹群，以阿拉伯芥为外群进行研究，在四个物种完成98个同源基因的分子序列，利用套装软体MCMCcoal来估算祖先物种的遗传变异，亦估算现生物种的核苷酸歧异度，观察到？多物种配对中祖先物种遗传多型性大於现生物种DNA歧异度，显示异域种化模型并无法完全解释阿拉伯芥属物种的种化模式，在某些物种配对间邻域种化模式应比异域种化更为可能；在基因树与物种树的比较，98个基因片段的亲缘模式只有28个是与已知物种树一致的，有23个基因其树状图支持{ lyrata} thaliana的型式，藉由kamchatica位置的变化以及估算各物种配对间的平均同义置换率，推测在A halleri ssp gemmifera与A lyrata ssp kamchatica间具有近代的单方向基因交流。

1Niche construction can lead to stable coexistence of diverse genotypes in spatially structured population, which supports a stable polymorphism even without heterozygote superiority.(2)With habitat deterioration, niche construction accelerates the formation of steady polymorphism and hence impedes the harmful influences of environment on the population, which might embody a life-history strategy of organism under the unfavorable environment.(3)Niche construction results in the coexistence with alternative polymorphism through genotype-environment feedback and limited gene flow.(4)The niche-constructing organism is an active force to alter its environment and hence the direction of natural selection in order to better survival.(5)Spatial dynamics and distribution pattern of metapopulation are profoundly influenced by time-lagged niche construction.(6)Metapopulation size can reach a fixed level in the recency effect and equal weighting of time lag but is statistical stability in primacy effect, which implies the primacy effect is most remarkable.(7)The increment in the relative weightingof each generation\' niche construction and the length of time lag are significant factors for system destabilization.(8)Moderate capacity of positive niche construction benefits the metapopulation persistence.(9)The narrowing of niche breadth can decrease the metapopulation size and thereby increase the extinction risk.(10)The coupled function of time lag and niche construction make the system oscillation and generate the spiral wave, spiral-broken and circular wave in heterogeneous habitat.The spatial distributions of metapopulation and resource content are complementary due to a phase lag of their both frequencies.(12)Metapopulation persistence with niche construction depends not only on the balance between colonization and extinction, but also on the balance between the ability of niche construction and natural dissipation of habitat.(13)Metapopula-tion can survive under certain condition when the percent of suitable patches in habitat is lower than the ration of extinction to colonization.(14)Two thresholds exist in the process of transition of habitat quality dynamics from unsuitable to suitable, which include the intensity of niche construction and the initial condition of system.(15)Metapopulation size is positive correlated with the ability of positive niche construction, which means that organism or population who has strongly positive influences on their environment plays an important role to maintain the available habitat.

通过上述几个方面的研究，主要得出以下15条结论：(1)生态位构建可使空间结构种群，甚至是在没有杂合子优势的条件下，形成多种可能的稳定基因型分布模式；(2)随着环境的破坏与恶化，种群的生态位构建作用加速其较早形成稳定多态以阻碍环境对种群的不利影响，解释了有机体在不利环境下的一种生活史对策；(3)生态位构建作用通过基因型—环境反馈机制及有限的基因交流导致基因型多态的稳定共存；(4)有机体的生态位构建作用是一种积极的动力改变环境进而改变其自然选择的方向；(5)生态位构建的时滞作用对集合种群动态和空间分布产生深刻影响；(6)集合种群大小在时滞的崭新效应和等权重效应下达到一固定值，而在首位效应下达到统计稳定，表明首位效应的影响最显著；(7)首位效应下生态位构建相对权重的增量和时滞的长度是影响系统不稳定性动态的关键因素；(8)适中的生态位构建强度有利于集合种群的续存；(9)生态位宽度变窄会减少集合种群的数量从而增加其灭绝风险；(10)时滞和生态位构建的双重作用使系统产生周期振荡，并在异质性环境中产生稳定的螺旋波，破碎的螺旋波和环形波三种分布模式；(11)集合种群与资源含量的空间分布因为相滞而互补；(12)具有生态位构建的集合种群续存不仅取决于侵占率与灭绝率之间的平衡，而且依赖于生态位构建能力同其生境的自然消耗速率之间的妥协；(13)当生境中适合侵占的斑块比例小于其侵占率与灭绝率之比时，生态位构建作用促使集合种群在一定条件下续存：(14)生境斑块的状态从不适合到适合转变过程中存在生态位构建强度和系统初始条件这两个阈值；(15)集合种群的大小同正生态位构建能力正相关，意味着对环境具有较强正作用的有机体对维持有效生境起积极作用。

High outcrossing rate might lead to high gene flow frequency and the maximum frequency of gene flow was determined by outcrossing rate.

实验结果显示，强烈的自花授粉竞争可能是导致栽培稻品种间极低的异交率以及基因漂移频率的主要原因之一。

When there was only one pollen donor, gene flow frequency was in direct proportion to the pollen density.(8) The strong pollen competition from self-pollination might contribute to the very low outcrossing rates and gene flow frequencies in rice varieties.(9) The study of rice pollen flow showed that with the artificial disturbance of pollen dispersal there were pollen grains detected at 90 m from the pollen sources.

9对水稻花粉流的研究显示，在赶粉的实验条件下，于远离花粉源的90 m处仍然检测到花粉分布，回归分析显示水稻的花粉可以传播100 m以上，甚至在远离花粉源的200 m的距离处仍然可能有花粉分布，这表明水稻的花粉可以传播非常远的距离。

When the pollen density of pollen donor exceeded the critical density, the gene flow frequency did not increased any longer, and the maximum gene flow frequency detected was equal to the outcrossing rate of pollen receiver in theory.

在其他因素都固定的情况下，如果花粉受体的异交率较高，那么到该花粉受体的基因漂移频率也相对较高。

To produce the scientific evidence for developing and manufacturing new antitumor drugs.Methods: 1 The inhibitory effect on cell growth of Hela was measured by MTT assay in treated or untreated groups (3.125, 6.25, 12.5, 25, 50μg/ml TAM and control) for three different treatment times (24h, 48h and 72h).2 Apoptosis and cell cycle were measured by FCM in four experimental groups (0, 4, 16, 40μg/ml TAM) for 48h.3 Adopting Wright and Giemse's staining to observe the morphology of Hela cells which treated with 40μg/ml TAM.4 Using invasion experiment to detect the Hela cells'invasive abilities which treated with 40μg/ml TAM.5 The protein expressional levels of P-ERK, ERK, C-myc and Cyclin D1 in Hela cells untreated or treated with 4, 16, 40μg/ml TAM for 24h were measured by Western blot.6 Expression of anti-apoptotic gene bcl-2, apoptotic gene bax and MMP-9 in Hela cells of four experimental groups (0, 4, 16, 40μg/ml TAM for 24h), were observed by revers transcription PCR.7 The protein expression of P-ERK, ERK, Bcl-2 and Bax in Hela cells treated with 40μg/ml TAM for 24h observed by laser scanning microscopes.

1采用四甲基偶氮唑蓝法检测不同浓度北豆根总碱(3.125、6.25、12.5、25、50μg/ml)处理不同时间(24、48和72小时)对Hela细胞增殖反应的抑制作用。2采用流式细胞技术(flow cytometry，FCM)检测不同浓度北豆根总碱(0、4、16、40μg/ml)作用48小时，对Hela细胞凋亡及周期变化的影响。3瑞氏-姬姆萨染色后显微镜观察北豆根总碱(0、40μg/ml)作用24小时后Hela细胞形态学变化。4采用Transwell小室法检测北豆根总碱(0、40μg/ml)作用24小时后对Hela细胞侵袭性的影响。5采用免疫印迹方法检测不同浓度北豆根总碱(0、4、16、40μg/ml)作用24小时后，Hela细胞中磷酸化ERK、ERK、C-myc、CyclinD1的表达变化。6采用逆转录-聚合酶链反应(revers transcription PCR，RT-PCR)半定量检测北豆根总碱(0、4、16、40μg/ml)作用24小时，Hela细胞抗凋亡基因bcl-2、促凋亡基因bax、基质金属蛋白酶-9(MMP-9)的表达变化。7应用激光共聚焦显微镜(laser scanning microscope，LSM)观察北豆根总碱(0、40μg/ml)作用24小时后，Hela细胞内P-ERK、ERK、Bcl-2、Bax蛋白的表达变化。

Furthermore, our study can provide valuable references for the pollen-mediated gene flow in other self- and wind-pollination crops, such as wheat, for the pollen-mediated gene flow models of wind-pollination crops may follow the same principles.

特别是花粉介导的基因漂移模型的一般形式，在风媒传粉作物间应该是一致的。

Our study can provide valuable references for the pollen-mediated gene flow in other self- and wind-pollination crops, such as wheat, for the pollen-mediated gene flow models of wind-pollination crops may follow the same principles.

特别是花粉介导的基因漂移模型的一般形式，在风媒传粉作物间应该是一致的。

The index (Gst=0.5284) presentes that 52.84% molecular variation existes among subpopulations, 47.16% existes within subpopulations. There are changes of genetic differentiation from 0.0000 to 1.0000. In addition, the gene flow of Aristida pennata populations is 0.4426, which suggests relative limited gene flow may be one of important factor influencing on the genetic structure of the species.

亚种群间的基因分化系数为0.5284，即有52.84％的遗传多样性存在于种群间，有47.16％遗传多样性存在于种群内，各位点的遗传分化程度差别较大(0～1.0000)，其基因流为0.4462，不足以防止漂变引起的种群间的遗传分化。

The possibilities of gene flow from wild Brassica juncea to transgenic glufosinate-and glyphosate-resistant gene oilseed rapes were studied by hand-pollination. The results demonstrated that the indexes of sexual compatibility of glufosinate-tolerant oilseed×wild B.

采用人工授粉的方法，分别以转基因抗草丁膦和抗草甘膦油菜为母本，野芥菜为父本，研究野芥菜的基因流动到转基因油菜中的可能性。

This one mode pays close attention to network credence foundation of the businessman very much.

这一模式非常关注商人的网络信用基础。

Cell morphology of bacterial ghost of Pasteurella multocida was observed by scanning electron microscopy and inactivation ratio was estimated by CFU analysi.

扫描电镜观察多杀性巴氏杆菌细菌幽灵和菌落形成单位评价遗传灭活率。