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1.
微型反向重复转座元件(miniature inverted repeat transposable element,MITE)是一类特殊的转座元件,在结构上与有缺失的DNA转座子相似,但具有反转录转座子高拷贝数的特点.MITE时常与基因相伴,对基因调控可能起重要作用,因此,MITE正逐渐成为基因和基因组进化及生物多样性研究的一种重要工具.本文综述了植物基因组MITE的结构、分类、活性及其应用研究进展. 相似文献
2.
果蝇转座因子对基因组进化的影响 总被引:2,自引:0,他引:2
真核生物基因组织有很多可移动DNA片段为称转座因子,果蝇是大量系统研究的最好实验材料之一,其基因组的10%-12%是由转座因子组成,在宿主中,TEs也许改变基因表达模型,也许改变ORFs编码序列,也许对细胞功能产生影响,这此因子遗传的可动性也可能使它们适于建造载体产生转基因生物。因此,对TEs进化的动态研究以及对宿主基因组进化影响的探索将有助于TEs作为载体的细胞工程研究。 相似文献
3.
石刁柏EST序列中微卫星分布特征分析 总被引:1,自引:0,他引:1
目的:开发新型石刁柏EST - SSR分子标记和开展相关的分子生物学研究.方法:利用EST - trimmer、Repeat Masker、SSRIT等生物信息学分析工具对石刁柏EST数据库中的EST序列进行去除poly A/T尾,载体、重复序列和低质量序列处理,并对EST序列中SSR分布特征进行了分析.结果:在NCBI数据库中下载的8 565条石刁柏EST序列中,重复次数超过5次的SSR共有610个,其中分布于601~ 800bp的EST - SSR标记最多,共464个,占SSR总数的77.33%;主要SSR重复基元类型是二核苷酸,共426个,占SSR总数的69.84%,其次是三核苷酸占SSR总数的29.18%.四核苷酸和五核苷酸的SSR仅各3个.结论:石刁柏EST中存在丰富的SSR信息,其中二核苷酸的AG/TC、GA/CT以及三核苷酸的CTT/GAA是SSR主要的重复单元. 相似文献
4.
Minkyu Park Pascal-Antoine Christin Jeffrey L Bennetzen 《Molecular biology and evolution》2021,38(9):3664
Limited genome resources are a bottleneck in the study of horizontal transfer (HT) of DNA in plants. To solve this issue, we tested the usefulness of low-depth sequencing data generated from 19 previously uncharacterized panicoid grasses for HT investigation. We initially searched for horizontally transferred LTR-retrotransposons by comparing the 19 sample sequences to 115 angiosperm genome sequences. Frequent HTs of LTR-retrotransposons were identified solely between panicoids and rice (Oryza sativa). We consequently focused on additional Oryza species and conducted a nontargeted investigation of HT involving the panicoid genus Echinochloa, which showed the most HTs in the first set of analyses. The comparison of nine Echinochloa samples and ten Oryza species identified recurrent HTs of diverse transposable element (TE) types at different points in Oryza history, but no confirmed cases of HT for sequences other than TEs. One case of HT was observed from one Echinochloa species into one Oryza species with overlapping geographic distributions. Variation among species and data sets highlights difficulties in identifying all HT, but our investigations showed that sample sequence analyses can reveal the importance of HT for the diversification of the TE repertoire of plants. 相似文献
5.
Steroidal saponins from roots of Asparagus officinalis 总被引:4,自引:0,他引:4
Sarsasapogenin M (1) and sarsasapogenin N (2), two new oligospirostanosides with a unique aglycone moiety, (25S)-5beta-spirostan-3beta, 17alpha-diol, along with seven known compounds (25S)-5beta-spirostan-3beta-ol-3-O-beta-d-glucopyranosyl-(1,2)-[beta-d-xylopyranosyl-(1,4)]-beta-d-glucopyranoside (3), (25S)-5beta-spirostan-3beta-ol-3-O-beta-d-glucopyranosyl-(1,2)-beta-d-glucopyranoside (4), (25S)-5beta-spirostan-3beta-ol-3-O-alpha-l-rhamnopyranosyl-(1,2)-[alpha-l-rhamnopyranosyl-(1,4)]-beta-d-glucopyranoside (5), (25S)26-O-beta-d-glucopyranosyl-5beta-furost-20 (22)-ene-3beta,26-diol-3-O-beta-d-glucopyranosyl-(1,2)-beta-d-glucopyranoside (6), yamogenin (7), beta-sitosterol (8), and sitosterol-beta-d-glucoside (9) were isolated from the roots of Asparagus officinalis L. Their structures were determined by spectral analysis, including extensive 1D and 2D NMR experiments. 相似文献
6.
作为重复序列的一种主要类型,转座子在高等植物基因组中具有相当丰富的DNA含量,在改变基因结构、调节基因表达、影响基因组进化,以及创造新基因的过程中扮演着重要的角色。Helitron转座子是DNA转座子的一种,在转座过程中经常捕获基因或基因片段,以及插入到基因附近或基因内部,因此在改变基因组构成、影响基因组的进化过程以及改变基因型和表型等方面起着重要作用。该文对国内外近年来有关植物基因组中helitron转座子的结构特征、鉴定和分类方法、基因组中的含量和在染色体上的分布,以及转座扩增和基因片段的捕获等方面的研究进展进行了综述,并对helitron转座子研究过程中存在的问题进行了讨论,对今后helitron相关的研究进行了展望。 相似文献
7.
Norio Shiomi 《Phytochemistry》1981,20(11):2581-2583
Two non-reducing hexasaccharides isolated from the roots of Asparagus officinalis were identified as 1F-β-fructofuranosyl-6G(1-β-fructofuranosyl)3sucrose and 1F(1-β-fructofuranosyl)2-6G(1-β-fructofuranosyl)2sucrose by examination of the constituent saccharides, GLC analysis of methyl derivatives, and investigation of partial acid hydrolysates and β-fructofuranosidase-catalysed hydrolysis products. 相似文献
8.
The Contribution of Transposable Elements to Expressed Coding Sequence in Arabidopsis thaliana 总被引:1,自引:0,他引:1
The goal of this study was to assess the extent to which transposable elements (TEs) have contributed to protein-coding regions
in Arabidopsis thaliana. To do this, we first characterized the extent of chimeric TE-gene constructs. We compared a genome-wide TE database to genomic
sequences, annotated coding regions, and EST data. The comparison revealed that 7.8% of expressed genes contained a region
with close similarity to a known TE sequence. Some groups of TEs, such as helitrons, were underrepresented in exons relative to their genome-wide distribution; in contrast, Copia-like and En/Spm-like sequences were overrepresented in exons. These 7.8% percent of genes were enriched for some GO-based
functions, particularly kinase activity, and lacking in other functions, notably structural molecule activity. We also examined
gene family evolution for these genes. Gene family information helped clarify whether the sequence similarity between TE and
gene was due to a TE contributing to the gene or, instead, the TE co-opting a portion of the gene. Most (66%) of these genes
were not easily assigned to a gene family, and for these we could not infer the direction of the relationship between TE and
gene. For the remainder, where appropriate, we built phylogenetic trees to infer the direction of the TE-gene relationship
by parsimony. By this method, we verified examples where TEs contributed to expressed proteins. Our results are undoubtedly
conservative but suggest that TEs may have contributed small protein segments to as many as 1.2% of all expressed, annotated
A. thaliana genes.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
9.
Potential Role of Transposable Elements in the Rapid Reorganization of the Fusarium oxysporum Genome
Jean-Michel Davire Thierry Langin Marie-Jose Daboussi 《Fungal genetics and biology : FG & B》2001,34(3):177-192
The activity of several families of transposable elements (TEs) in the genome of Fusarium oxysporum represents a potential source of karyotypic instability. We investigated transposon-mediated chromosome rearrangements by analyzing the karyotypes of a set of strains in which transposition events had occurred. We uncovered exceptional electrophoretic karyotype (EK) variability, in both number and size of chromosomal bands. We showed that EK differences result from chromosomal translocations, large deletions, and even more complex rearrangements. We also revealed many duplicated chromosomal regions. By following transposition of two elements and analyzing the distribution of different families of TEs on whole chromosomes, we find (i) no evidence of chromosomal breakages induced by transposition, (ii) a clustering of TEs in some regions, and (iii) a correlation between the high level of chromosomal polymorphism and the concentration of TEs. These results suggest that chromosome length polymorphisms likely result from ectopic recombination between TEs that can serve as substrates for these changes. 相似文献
10.
Kent M. Reed 《Marine biotechnology (New York, N.Y.)》1999,1(1):60-67
This study reports on the DNA sequence of a Tc1-like transposable element Tsn1 from lake trout (Salvelinus namaycush). Tc1-like elements were amplified by PCR using an oligonucleotide primer based on the Tdr1 element of zebrafish. One full-length and two partial-length copies of the transposon were sequenced. In addition, partial
Tsn1 elements were recovered from PCR reactions run with primers specific to the 3′ terminus of the 28S rDNA. However, sequence
analysis of cloned fragments found that these sequences were not associated with the rDNA cistron. Sequence comparisons indicate
that Tsn1 is a type A element common to both salmonid and cyprinid fishes. The consensus sequence of the full-length element (Tsn1) was 1643 nucleotides with long terminal repeats (LTRs) of 225 nucleotides. Tsn1 contains a transposase coding region corresponding to 340 amino acids that includes all of the functional elements of Tc1-like transposons. Southern analysis found a high proportion of the Tsn1 transposons in the lake trout genome to be full-length copies.
Received March 7, 1998; accepted July 20, 1998 相似文献
11.
12.
An Agrobacterium-transformed cell culture from the monocot Asparagus officinalis 总被引:16,自引:1,他引:15
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Cultured stem fragments from the monocotyledonous plant Asparagus officinalis infected by the oncogenic bacterium Agrobacterium tumefaciens developed tumorous proliferations. This tissue was propagated in vitro on hormone-free culture medium. The T-DNA-encoded markers nopaline and agrocinopine were unambiguously detected in these tissues. The data demonstrate that stable T-DNA transfer as well as expression of T-DNA genes is possible in at least some monocotyledonous plants. This opens new possibilities for plant genetic engineering using the Ti plasmid as a gene vector. 相似文献
13.
Transposable elements (TEs) are commonly thought to be of universal occurrence in eukaryotes. Analysis of complete higher eukaryotic genomes confirms the TE status as substantial genome components and provides insights into their role in shaping the genome structure of extant eukaryotes. This review addresses several recently investigated problems in transposon biology, including the potential roles of promoter organization in transposon function and evolution, the ubiquity of TEs in numerous phyla of the animal kingdom, and the possible connection between transposon content and mode of reproduction. 相似文献
14.
We have performed a phylogenetic analysis of 59 mariner elements in 14 Drosophilidae species that are related to the active Drosophila mauritiana Mos1 element. This includes 38 previously described sequences and 21 new sequences amplified by PCR from 10 species. Most of the
elements detected are nonfunctional due to several frameshifts and deletions. They have been subdivided into four groups according
to specific signatures in the nucleotidic and amino acid sequences. The mean nucleotide diversity is 4.8 ± 0.1% and reflects
mainly the divergence of inactive elements over different periods. Although this probably gives rise to occasional homoplasies
between distantly related taxa, the elements of each species remain grouped together. Horizontal transfer, reported previously
between D. mauritiana and Zaprionus tuberculatus, can be extended to Z. verruca, while the Mos1-like element of Z. indianus belongs to another group. Interpretation of the phylogeny leads to a comparison of the influence of common ancestral sequences
and putative horizontal transfers.
Received: 31 May 1999 / Accepted: 28 June 1999 相似文献
15.
16.
Endornaviruses have large double-stranded RNA (dsRNA) genomes that carry a single open reading frame (ORF). Here we report the complete genome of a novel endornavirus, assembled from next-generation sequence data generated from Vitis vinifera-extracted dsRNA. Two different fungal hosts have been identified for this virus, suggesting that horizontal transmission of the virus is possible. 相似文献
17.
One new (Sarsasapogenin O) and seven known steroids were isolated from the roots of Asparagus officinalis L. Their structures were elucidated on the basis of spectroscopic analysis, including various 2D-NMR techniques, hydrolysis,and by comparison of spectral data of known compounds. These compounds together with nine steroids which were previously isolated from this plant, were tested for cytotoxic activity. Among them, eight compounds displayed significant cytotoxicities against human A2780, HO-8910, Eca-109, MGC-803, CNE, LTEP-a-2, KB and mouse L1210 tumor cells. 相似文献
18.
The metabolism of L-asparagine in Asparagus officinalis 总被引:4,自引:0,他引:4
D A Cooney N Jayaram S G Swengros S C Alter M Levine 《The International journal of biochemistry》1980,11(1):69-83
19.
We have characterised from Xenopus laevis two new short interspersed repetitive elements, we have named Glider and Vision, that belong to the family of miniature inverted-repeat
transposable elements (MITEs). Glider was first characterised in an intronic region of the α-tropomyosin (α-TM) gene and database
search has revealed the presence of this element in 10 other Xenopus laevis genes. Glider elements are about 150 bp long and for some of them, their terminal inverted repeats are flanked by potential
target-site duplications. Evidence for the mobility of Glider element has been provided by the presence/absence of one element
at corresponding location in duplicated α-TM genes. Vision element has been identified in the promoter region of the cyclin
dependant kinase 2 gene (cdk2) where it is boxed in a Glider element. Vision is 284 bp long and is framed by 14-bp terminal
inverted repeats that are flanked by 7-bp direct repeats. We have estimated that there are about 20,000 and 300 copies of
Glider and Vision respectively scattered throughout the laevis genome. Every MITEs elements but two described in our study
are found either in 5′ or in 3′ regulatory regions of genes suggesting a potential role in gene regulation.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献