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1.
圆斑星鲽及相关种类线粒体DNA控制区结构分析   总被引:2,自引:0,他引:2  
采用PCR产物直接测序法测定了圆斑星鲽(Verasper variegatus)的24个个体的线粒体控制区(Control region)核苷酸全序列, 并进行了结构分析。结果表明, 圆斑星鲽线粒体控制区核苷酸全序列具有长度多态性, 得到4种长度单元型, 主要表现为控制区中的串联重复序列的长度不同。对鲽形目鱼类如鲽科的条斑星鲽(Verasper moseri)、黄盖鲽(Limanda feruginea)、马舌鲽 (Reinhardtius hippoglossoides), 美洲拟庸鲽(Heppoglossoides platessoides )和鲆科的牙鲆(Paralichthys olivaceus)以及鳎科的欧洲鳎(Solea solea)、塞内加尔鳎(S. senegalensis)和沙鳎(S. lascari)的控制区的比较研究发现, 鲽形目鱼类的线粒体控制区均存在相似的结构, 即线粒体控制区可分为终止相关序列区(ETAS)、中央保守区(包括CSB-A、CSB-B、CSB-C、CSB-D、CSB-E、CSB-F)以及保守序列区(CSB1、CSB2、CSB3)和重复序列区(Repeat region)4个区域。通过与脊椎动物各个纲线粒体控制区序列的比较分析, 发现只有鲽形目(包括鲆、鲽类和鳎类)鱼类和两栖纲的无尾类在CSB-3之后存在相似的串联重复序列。  相似文献   

2.
王谈笑  郑伟  陈菁  王炜  徐晓丹 《广西植物》2017,37(3):329-334
该研究对我国西南地区钩苞大丁草(Gerbera delavayi)9个居群rDNA ITS序列进行PCR的扩增和检测序列,并以非洲菊(G.jamesonii)的ITS序列作为外类群,比较了序列之间的差异,同时分析了钩苞大丁草不同居群在地理距离与遗传距离之间的关系,构建了NJ系统发育树。结果表明:(1)钩苞大丁草9个居群的ITS序列全长介于600~700 bp之间,平均长度约为657 bp,其中,ITS1长度为243~246 bp,(G+C)含量为45.67%~46.80%之间,5.8S长度191~193 bp,(G+C)含量为58.60%~58.61%之间,ITS2长度为220~221 bp,(G+C)含量为57.00%~57.45%之间;ITS序列共有22个变异位点,ITS1序列(17个)、5.8S序列(2个)以及ITS2序列(3个)上均有变异。(2)地理距离与遗传距离有正相关(r2=0.652),序列间遗传分化距离为0.001 1~0.024 3,其中普洱居群与其他居群间遗传距离最大。(3)钩苞大丁草9个居群分成三个分支,普洱居群单独成支,丽江和洱源居群聚为一支,富源、武定、德昌、石林、新平和开远6个居群聚为一支。rDNA ITS序列可以用于钩苞大丁草群体遗传研究的分析,该研究结果为其保护性开发提供了参考依据。  相似文献   

3.
基于ITS序列的新疆野苹果系统发育分析   总被引:1,自引:0,他引:1  
利用PCR和DNA测序技术,获取3个居群新疆野苹果的ITS序列,并结合GenBank里已有的中亚地区的新疆野苹果、欧洲苹果、栽培苹果和东方苹果的ITS序列进行比对分析,利用MEGA5.0软件选择" Krima2-Paramenter"核酸距离模式获得遗传距离矩阵,用邻接法(neighbor-joining,NJ )进行独立的系统发育分析,结果显示,所有供试材料的ITS1的长度为209~224 bp,GC含量为66.1%~66.9%,ITS2的长度为201~290 bp,GC含量为65%~71.5%,遗传距离为0~0.21,进化树分为三支.新疆野苹果的遗传多样性与地理分布有正相关关系,不同居群之间存在基因交流.  相似文献   

4.
以陕西、四川、浙江、重庆、福建、广西主产区的11个种源厚朴为材料,采用PCR直接测序法,测定不同产区厚朴的核糖体DNA ITS区序列,并结合GeneBank中相关植物的ITS序列(以同属近缘物种辛夷为外类群),应用Kimura 2遗传距离与NJ系统树分析法对不同产区厚朴的亲缘关系进行分析。结果表明:11个产区厚朴的ITS全序列长度介于593~600 bp,其中,ITS1长度为214~217 bp,G+C含量为54.42%~5535%,ITS2长度为215~219 bp,G+C含量为59.82%~60.95%;ITS序列共有36个变异位点,均出现在ITS1(7个)和ITS2(29个)序列中,虽然位点变异与部分叶形变化出现吻合,但无必然联系;序列间遗传分化距离为0.000~0.02792,11个产区厚朴构成3个分支,显示出产区间厚朴的亲缘关系,其中陕西洋县(SXYX)、陕西西乡(SXXX)、福建武夷山(FJWYS)及四川彭州(SCPZ)四个产区ITS序列完全一致。nrDNA ITS序列分析可作为厚朴不同产区亲缘关系鉴定的手段。  相似文献   

5.
帘蛤科贝类rDNA内转录间隔区序列的研究   总被引:5,自引:0,他引:5  
根据18SrDNA、5.8SrDNA和28SrDNA保守序列设计引物,应用聚合酶链式反应(PCR)扩增了文蛤(Meretrix meretrix L.)、青蛤(Cyclina sinensis G)、硬壳蛤(Mercenaria mercenaria L.)和江户布目蛤(Protothaca jedoensis L.)4种帘蛤科贝类的第一内转录间隔区(ITS1)和第二内转录间隔区(ITS2)序列,并进行了测序。结果表明,文蛤、青蛤、硬壳蛤和江户布目蛤的ITS1扩增产物大小分别为978bp、663bp、757bp和942bp,GC含量分别为61.55%、60.78%、62.48%和64.86%~64.97%,其中ITS1序列长度分别为900bp、585bp、679bp和864bp,是迄今已报道双壳贝类中变化范围最大的,GC含量分别为61.67%、61.03%、63.03%和65.51%~65.62%,江户布目蛤种内ITS1序列有个体差异;ITS2扩增产物大小分别为644bp、618~620bp、593bp和513~514bp,GC含量分别为61.18%、61.29%~61.81%、62.73%和61.48%61.60%,其中ITS2序列长度分别为412bp、386~388bp、361bp和281~282bp,GC含量分别为65.29%、65.21%~66.06%、67.87%和67.38%~67.62%,青蛤和江户布目蛤种内ITS2序列有个体差异。4种蛤ITS1和ITS2序列种间差异很大,有明显的长度多态性,ITS2种间序列相似度73.0%~89.1%,与ITS1的种间序列相似度48.7%~81.5%相比略高。此外,在4种蛤ITS1和ITS2序列中各发现2个与rRNA加工有关的保守区。通过对ITS1和ITS2序列的组装获得了4种蛤5.8SrRNA基因完整序列,序列长度都是157bp,GC含量57.96%~58.60%,4种蛤5.8SrRNA基因相对保守,种间序列差异度0-6.0%,共有10个变异位点,其中转换4处,颠换6处,硬壳蛤和江户布目蛤5.8SrRNA基因序列完全相同。以ITS2序列(包含5.8SrRNA和28SrRNA基因部分序列)为标记,调用北极蛤科的Arctica islandica相应序列数据作外群,构建了帘蛤科贝类的系统发育树,其拓扑结构显示江户布目蛤与硬壳蛤亲缘关系最近,青蛤与其他3物种的亲缘关系最远。  相似文献   

6.
目的:研究苏铁珊瑚根共生念珠藻16SrDNA-23SrDNA基因间隔序列(ITS)拷贝数。方法:提取苏铁珊瑚根共生念珠藻全DNA,PCR扩增其16SrDNA-23SrDNA基因间隔序列(ITS)克隆并测序;采用Cluster X 1.83对所得序列进行比对,用DNAman软件对比对结果进行人工校正;采用割胶回收电泳检测、菌液PCR及混合模板PCR扩增三种方法验证ITS-L2。结果:ITS-S(420 bp)不含任何氨基酸编码序列,ITS-L1(676 bp)包含一个异亮氨酸和一个丙氨酸编码序列;ITS-L1和ITS-L2在琼脂糖凝胶电泳检测时长度分别为676 bp和1000 bp,而谱带经克隆测序后结果表明ITS-L1和ITS-L2碱基序列和长度几乎相同,仅有两个碱基发生变异。结论:ITS-L2为假阳性,可能是由ITS-S和ITS-L1形成的异源双链;苏铁珊瑚根共生念珠藻含有两种类型的ITS拷贝,一种是含有tRNAIle和tRNAAla编码序列的ITS,另一种是不含tRNAIle和tRNAAla编码序列的ITS。  相似文献   

7.
为探讨刺参科海参和海参科海参的系统进化关系,本研究通过PCR技术获取19种刺参科和海参科海参的ITS2序列,从NCBI上获取瓜参(C. salma)的ITS2序列。结果表明ITS2序列具有长度多态性,从318 bp (绿刺参)到591 bp (白尼参属)。海参属的ITS2序列长度多态性高,ITS2的GC含量从56.7%(糙海参)到70.6%(瓜参)。海参ITS2序列保守性不高,仅有48个保守位点,其余均为变异位点。基于ITS2的系统进化树结果显示进化树主要分成两支,一支包括海参科的4个属:海参属、白尼参属、辐肛参属和格皮氏海参属。辐肛参属和格皮氏海参属为姐妹关系,二者聚在一起后与白尼参属聚为一支,随后再与海参属聚在一起。白尼参属和辐肛参属为单系,海参属为复系。另一支为C. salma和刺参科。梅花参属与刺参属聚为一支后,再与仿刺参属聚在一起,3个属都是单系。在20种海参中,S. naso与B. argus的遗传距离最大(6.415)。刺参属中,S. monotuberculatus和S. horrens遗传距离最近(0.012),海参属中,糙海参与H. fuscopunctata的遗传距离最大(3.24)。本研究为从分子水平上研究海参科和刺参科之间的系统进化关系奠定了基础。  相似文献   

8.
目前,我国西施舌群体分子遗传差异研究结果存在争议。分析我国南北沿海(9个群体)、与广西北海毗邻的越南(1个群体)西施舌核DNA的内转录间隔区2(ITS2)和线粒体DNA的16S rRNA基因(16S)片段核苷酸序列及其二级结构,为解决争议问题提供分子生物学资料。扩增获得西施舌ITS2片段和16S序列,其长度分别为389-402 bp和306 bp,加之下载序列共147条;序列分析显示,74个ITS2序列共有17种基因型,73个16S序列有15种单倍型,其中,长乐(CL)群体独享9种ITS2基因型和5种16S单倍型,非长乐群体(nCL)多数为群体间交叉共享1种或几种基因(单倍)型;基因(单倍)型核苷酸变异位点占5.7%(ITS2)和11.8%(16S);基于ITS2和16S的CL群体和nCL群体间的遗传距离与群体内遗传距离之比分别为2.42和11.08,nCL群体间的平均遗传距离均为0.007;二级结构显示CL群体ITS2的9种基因型和16S的5种单倍型均区别于nCL群体,nCL的ITS2和16S二级结构分别相似;ITS2和16S基因的系统发育分析显示,CL西施舌形成支持率很高(98,96)的单系支,而nCL群体则交叉聚为另一支(98,96)。研究结果揭示,福建西施舌是腔蛤蜊属(Coelomactra)的一个新种。  相似文献   

9.
虎耳草科(Saxifragaceae)常山属(Dichroa)植物常山(Dichroa febrifuga Lour.)是我国著名的抗疟药物。但目前全国各地使用较为混乱,代用品、混淆品多,鉴定困难。本研究收集常山及其混伪品6种,共64份样品,利用DNA条形码和二维DNA条形码技术进行物种鉴定研究。研究结果表明,DNA条形码技术可准确鉴定常山及其混伪品,20%的常山样品存在混伪现象,混伪品主要为阔叶十大功劳(Mahonia bealei(Fort.) Carr.)。常山ITS2序列长度为230 bp,种内K2P遗传距离为0~0.0253,常山及其混伪品种间K2P遗传距离为0.152~0.748。基于ITS2序列构建的NJ树显示,常山及其混伪品能够明显区分,可为临床安全用药提供科学依据。成功构建常山的二维DNA条形码鉴定体系,实现“互联网+”的跨平台信息交换,可为二维DNA条形码技术在流通监管领域的实践应用提供理论基础。  相似文献   

10.
运用PCR扩增产物直接测序的方法对云南、安徽的乌头及其近缘种植物的ITS区碱基序列测定。表明核糖体DNA中ITS区的完整序列(包括ITS1,ITS2和5.8s),4种乌头属植物的ITS1序列长度为249bp,云南鸟头和安徽乌头及黄山鸟头ITS2序列长度为189bp,赣皖乌头ITS2序列长度为217bp。运用Mega2软件进行系统分析得到系统进化树。ITS序列特征是乌头鉴别的有效分子标记。  相似文献   

11.
在工业生物催化过程和生物细胞工厂构建方面,蛋白质定向进化被广泛地应用于酶的分子改造.蛋白质定向进化不仅可以针对某一目的蛋白进行改造,还可以改善代谢途径、优化代谢网络、获得期望表型细胞.为了获得更高效的突变效率,快捷、高通量的筛选方法,提高蛋白质定向进化的效果,研究者不断开发蛋白质体内、体外进化方法,取得了新的进展和应用.本文介绍了最近发展的蛋白质定向进化技术的原理、方法及特点,总结了突变文库的筛选方法和蛋白质定向进化的最新应用,最后讨论了蛋白质定向进化存在的挑战和未来发展方向.  相似文献   

12.
Evolutionary responses to the long-term exploitation of individuals from a population may include reduced growth rate, age at maturation, body size and productivity. Theoretical models suggest that these genetic changes may be slow or impossible to reverse but rigorous empirical evidence is lacking. Here, we provide the first empirical demonstration of a genetically based reversal of fishing-induced evolution. We subjected six populations of silverside fish (Menidia menidia) to three forms of size-selective fishing for five generations, thereby generating twofold differences among populations in mean weight and yield (biomass) at harvest. This was followed by an additional five generations during which size-selective harvest was halted. We found that evolutionary changes were reversible. Populations evolving smaller body size when subjected to size-selective fishing displayed a slow but significant increase in size when fishing ceased. Neither phenotypic variance in size nor juvenile survival was reduced by the initial period of selective fishing, suggesting that sufficient genetic variation remained to allow recovery. By linear extrapolation, we predict full recovery in about 12 generations, although the rate of recovery may taper off near convergence. The recovery rate in any given wild population will also depend on other agents of selection determined by the specifics of life history and environment. By contrast, populations that in the first five generations evolved larger size and yield showed little evidence of reversal. These results show that populations have an intrinsic capacity to recover genetically from harmful evolutionary changes caused by fishing, even without extrinsic factors that reverse the selection gradient. However, harvested species typically have generation times of 3–7 years, so recovery may take decades. Hence, the need to account for evolution in managing fisheries remains.  相似文献   

13.
The geographical distribution of sexual and related asexual species has been suggested to correlate with habitat stability; sexual species tend to be in stable habitats (K‐selection), whereas related asexual taxa tend to be in unstable habitats (r‐selection). We test whether this broad‐scale pattern can be re‐created at a microevolutionary scale by experimentally evolving populations of facultatively sexual rotifers under different ecological conditions. Consistent with the pattern in nature, we find that the rate of sex evolves to lower levels in the r‐selected than in K‐selection environments. We consider several different explanations for these results.  相似文献   

14.
The problem of modifier evolution was examined with regard to the idea that modifier evolution can be considered as a result of selection for adaptation speed in populations far from equilibrium. This kind of selection was called feedback selection in order to emphasize the difference to theories which consider modifier evolution near the equilibrium. The basic principles of this kind of selection are derived for asexual populations and the problem of dominance is discussed in the light of this concept. In general the results support the view, that the genetic properties of a character are selected along with the character itself.This work was supported by the Austrian Fonds zur Förderung der Wissenschaftlichen Forschung (Proj. Nr. 3502).  相似文献   

15.
16.
Abstract How often will natural selection drive parallel evolution at the DNA sequence level? More precisely, what is the probability that selection will cause two populations that live in identical environments to substitute the same beneficial mutation? Here I show that, under fairly general conditions, the answer is simple: if a wild‐type sequence can mutate to n different beneficial mutations, replicate populations will on average fix the same mutation with probability P= 2/(n + 1). This probability, which is derived using extreme value theory, is independent of most biological details, including the length of the gene in question and the precise distribution of fitness effects among alleles. I conclude that the probability of parallel evolution under natural selection is nearly twice as large as that under neutrality.  相似文献   

17.
Optimality models have been used to predict evolution of many properties of organisms. They typically neglect genetic details, whether by necessity or design. This omission is a common source of criticism, and although this limitation of optimality is widely acknowledged, it has mostly been defended rather than evaluated for its impact. Experimental adaptation of model organisms provides a new arena for testing optimality models and for simultaneously integrating genetics. First, an experimental context with a well‐researched organism allows dissection of the evolutionary process to identify causes of model failure – whether the model is wrong about genetics or selection. Second, optimality models provide a meaningful context for the process and mechanics of evolution, and thus may be used to elicit realistic genetic bases of adaptation – an especially useful augmentation to well‐researched genetic systems. A few studies of microbes have begun to pioneer this new direction. Incompatibility between the assumed and actual genetics has been demonstrated to be the cause of model failure in some cases. More interestingly, evolution at the phenotypic level has sometimes matched prediction even though the adaptive mutations defy mechanisms established by decades of classic genetic studies. Integration of experimental evolutionary tests with genetics heralds a new wave for optimality models and their extensions that does not merely emphasize the forces driving evolution.  相似文献   

18.
Summary The recent evaluation by Fitch (1980) of REH theory for macromolecular divergence is a severely erroneous and distorted analysis of our work over the past decade. We reply to those distortions here. At present, there is no factual basis for believing Fitch's assessment that corrections which move evolutionary estimates of total mutations fixed closer to the true distance must do so at the expense of an increased variance sufficient to compromise the value of the improvement. By direct calculation the variance in the estimates of total mutations fixed given by REH theory is comparable to that of other models now in the literature for the case in which genetic events are equiprobable. A general argument is given that suggests that, as we consider more and more carefully the selective, functional, and structural constraints on the evolution of genes and proteins, this variance may be expected to decrease toward a lower bound.  相似文献   

19.
Traditional approaches to the directed evolution of genes of interest (GOIs) place constraints on the scale of experimentation and depth of evolutionary search reasonably achieved. Engineered genetic systems that dramatically elevate the mutation of target GOIs in vivo relieve these constraints by enabling continuous evolution, affording new strategies in the exploration of sequence space and fitness landscapes for GOIs. We describe various in vivo hypermutation systems for continuous evolution, discuss how different architectures for in vivo hypermutation facilitate evolutionary search scale and depth in their application to problems in protein evolution and engineering, and outline future opportunities for the field.  相似文献   

20.
Mammalian olfaction comprises two chemosensory systems: the odorant-detecting main olfactory system (MOS) and the pheromone-detecting vomeronasal system (VNS). Mammals are diverse in their anatomical and genomic emphases on olfactory chemosensation, including the loss or reduction of these systems in some orders. Despite qualitative evidence linking the genomic evolution of the olfactory systems to specific functions and phenotypes, little work has quantitatively tested whether the genomic aspects of the mammalian olfactory chemosensory systems are correlated to anatomical diversity. We show that the genomic and anatomical variation in these systems is tightly linked in both the VNS and the MOS, though the signature of selection is different in each system. Specifically, the MOS appears to vary based on absolute organ and gene family size while the VNS appears to vary according to the relative proportion of functional genes and relative anatomical size and complexity. Furthermore, there is little evidence that these two systems are evolving in a linked fashion. The relationships between genomic and anatomical diversity strongly support a role for natural selection in shaping both the anatomical and genomic evolution of the olfactory chemosensory systems in mammals.  相似文献   

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