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假基因(pseudogene)是指基因组中与正常基因序列相似, 但是缺乏功能的DNA 序列。通过序列同源性搜索, 可以收集基因组中假基因的群体特性、染色体分布和同源家族等特性。假基因很好地保留了数百万年前基因组中祖先基因的分子记录, 被视为“基因化石”, 因此假基因在进化和比较基因组学中是重要的资源。应用假基因和基因比较体系, 可以探究生物基因的进化史和基因组稳定性。如: 用Ka/Ks比值确定假基因的自然选择压、物种亲缘关系和进化距离, 分析假基因自身的进化趋势, 探讨DNA 突变的成因等。 相似文献
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假基因的组成、分布及其分子进化 总被引:5,自引:0,他引:5
假基因(pseudogene)是指基因组中与正常基因序列相似,但是缺乏功能的DNA序列.通过序列同源性搜索,可以收集基因组中假基因的群体特性、染色体分布和同源家族等特性.假基因很好地保留了数百万年前基因组中祖先基因的分子记录,被视为"基因化石",因此假基因在进化和比较基因组学中是重要的资源.应用假基因和基因比较体系,可以探究生物基因的进化史和基因组稳定性.如:用Ka/Ks比值确定假基因的自然选择压、物种亲缘关系和进化距离,分析假基因自身的进化趋势,探讨DNA突变的成因等. 相似文献
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假基因(pseudogene)是出现在特定种群基因组中无功能的基因拷贝,在不同的生命形式特别是脊椎动物中较为常见,未加工假基因和加工假基因的产生机制不同,在分子遗传学领域,识别假基因结构和功能有非常重要的作用。 相似文献
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分析了人类加工假基因在染色体上的分布,发现加工假基因密度与重组率负相关,而与基因密度正相关。加工假基因在低重组区的积累与插入有害模型和异位重组模型相吻合:在插入有害模型下,低重组区的选择强度由于Hill.Robertson干涉而变弱,所以加工假基因较多地插入到低重组区;在异位重组模型下,同源加工假基因家族(包括同源祖先基因)之内可能发生异位重组而对机体造成危害,所以加工假基因在高重组区的插入受到较强的负选择,导致加工假基因较多地分布在低重组区。除以上两种模型以外,加工假基因还可能通过降低重组率的方式对加工假基因密度与重组率的负相关有所贡献。加工假基因偏好分布在基因密区,这可能与异位重组在该区较少发生有关。 相似文献
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在真菌、昆虫、无脊椎动物和脊椎动物等许多分类单元中,都已发现mtDNA序列的核转座现象。在PCR扩增时,往往同时扩增出mtDNA和细胞核中线粒体假基因(Numts),Numts混淆系统发育和群体遗传研究,得出错误的结果。本文综述了Numts的检查和避免的方法,以及在进化生物学研究中的应用进展。 相似文献
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被称为"垃圾基因"的假基因是真核生物基因组中的重要组成部分。近年来对假基因的功能研究表明其并非是基因组中的沉默成员。如一些假基因参与RNA转录,一些假基因转录本能够形成小干扰RNA(siRNA),通过小RNA干扰作用调节功能基因。另外,还有研究发现,一些假基因能够通过microRNA调节肿瘤抑制因子。然而,对假基因功能的深入挖掘需要建立在对其更精准、更全面的鉴定基础之上。随着各物种全基因组测序的完成及序列比对算法的完善,全面而又精确地鉴定假基因已经成为可能。下文就近年来假基因相关鉴定方法、调节功能以及在进化上的意义进行了阐述,并对未来假基因研究方向进行了展望。 相似文献
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人类基因组的研究进展达来内蒙古大学生物学系,呼和浩特,010021)人类基因组计划是1990年10月正式实施的为期15年耗资30亿美元的宏伟工程。它的任务是完成高精度的人类基因组遗传学图谱和物理图谱,测定人和几个模式生物的基因组DNA序列,是广泛的国... 相似文献
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INTRODUCTIONNuclearpseudogenesofmitochondrial(mt)DNAwereinitiallydiscoveredintheearly80's[1--6].However,mechanismsforthegenerationofmtDNApseudogenesarestillnotclearandmayvaryindifferentcases.BothRNA--[7--8]andDNAmediated[9--11]processeshavebeensugges... 相似文献
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The aim of this article is to demonstrate possible recombination‐associated evolutionary forces affecting the genomic distribution of processed pseudogenes. The relationship between recombination rate and the distribution of processed pseudogenes is analysed in the human genome. The results show that processed pseudogenes preferentially accumulate in regions of low recombination rates and this correlation cannot be explained by indirect relationships with GC content and gene density. Several explanatory models for the observation are discussed. A model of selection against ectopic recombination is tested based on the difference in distribution pattern between two classes of processed pseudogenes, which differ in the possibility of stimulating ectopic recombination. Our results indicate that the correlation between processed pseudogene density and recombination rate is probably results, in part, from the selection against ectopic recombination between closely located homologous processed pseudogenes. We also found a length effect in processed pseudogene distribution, namely long processed pseudogenes are located more preferentially in regions of low recombination rates than short ones. 相似文献
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The p34cdc2 protein and other cyclin-dependent protein kinases (CDK) are important regulators of eukaryotic cell cycle progression. We have previously cloned a functional cdc2 gene from Picea abies and found it to be part of a family of related sequences, largely consisting of pseudogenes. We now report on the isolation of partial cdc2 pseudogenes from Picea engelmannii and Picea sitchensis, as well as partial functional cdc2 sequences from P. engelmannii, P. sitchensis and Pinus contorta. A high level of conservation between species was detected for these sequences. Phylogenetic analyses of pseudogene and functional cdc2 sequences, as well as the presence of shared insertions or deletions, support the division of most of the cdc2 pseudogenes into two subfamilies. New cdc2 pseudogenes appear to have been formed in Picea at a much higher rate than they have been obliterated by neutral mutations. The pattern of nucleotide changes in the cdc2 pseudogenes, as compared to a presumed ancestral functional cdc2 gene, was similar to that previously found in mammalian pseudogenes, with a strong bias for the transitions C to T and G to A, and the transversions C to A and G to T. 相似文献
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Hui‐Su Kim Bo‐Young Lee Jeonghoon Han Chang‐Bum Jeong Dae‐Sik Hwang Min‐Chul Lee Hye‐Min Kang Duck‐Hyun Kim Hee‐Jin Kim Spiros Papakostas Steven A. J. Declerck Ik‐Young Choi Atsushi Hagiwara Heum Gi Park Jae‐Seong Lee 《Molecular ecology resources》2018,18(3):646-655
Monogononta is the most speciose class of rotifers, with more than 2,000 species. The monogonont genus Brachionus is widely distributed at a global scale, and a few of its species are commonly used as ecological and evolutionary models to address questions related to aquatic ecology, cryptic speciation, evolutionary ecology, the evolution of sex and ecotoxicology. With the importance of Brachionus species in many areas of research, it is remarkable that the genome has not been characterized. This study aims to address this lacuna by presenting, for the first time, the whole‐genome assembly of the freshwater species Brachionus calyciflorus. The total length of the assembled genome was 129.6 Mb, with 1,041 scaffolds. The N50 value was 786.6 kb, and the GC content was 24%. A total of 16,114 genes were annotated with repeat sequences, accounting for 21% of the assembled genome. This assembled genome may form a basis for future studies addressing key questions on the evolution of monogonont rotifers. It will also provide the necessary molecular resources to mechanistically investigate ecophysiological and ecotoxicological responses. 相似文献
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