Molecular and cytogenetic analysis of repetitive DNA in pea (Pisum sativum L.)

Genome ◽  
2001 ◽  
Vol 44 (4) ◽  
pp. 716-728 ◽  
Author(s):  
Pavel Neumann ◽  
Marcela Nouzová ◽  
Jirí Macas

A set of pea DNA sequences representing the most abundant genomic repeats was obtained by combining several approaches. Dispersed repeats were isolated by screening a short-insert genomic library using genomic DNA as a probe. Thirty-two clones ranging from 149 to 2961 bp in size and from 1000 to 39 000/1C in their copy number were sequenced and further characterized. Fourteen clones were identified as retrotransposon-like sequences, based on their homologies to known elements. Fluorescence in situ hybridization using clones of reverse transcriptase and integrase coding sequences as probes revealed that corresponding retroelements were scattered along all pea chromosomes. Two novel families of tandem repeats, named PisTR-A and PisTR-B, were isolated by screening a genomic DNA library with Cot-1 DNA and by employing genomic self-priming PCR, respectively. PisTR-A repeats are 211–212 bp long, their abundance is 2 × 104 copies/1C, and they are partially clustered in a secondary constriction of one chromosome pair with the rest of their copies dispersed on all chromosomes. PisTR-B sequences are of similar abundance (104 copies/1C) but differ from the "A" family in their monomer length (50 bp), high A/T content, and chromosomal localization in a limited number of discrete bands. These bands are located mainly in (sub)telomeric and pericentromeric regions, and their patterns, together with chromosome morphology, allow discrimination of all chromosome types within the pea karyotype. Whereas both tandem repeat families are mostly specific to the genus Pisum, many of the dispersed repeats were detected in other legume species, mainly those in the genus Vicia.Key words: repetitive DNA, plant genome, retroelements, satellite DNA, Pisum sativum.

Genes ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 1014 ◽  
Author(s):  
Ana Paço ◽  
Renata Freitas ◽  
Ana Vieira-da-Silva

Eukaryotic genomes are rich in repetitive DNA sequences grouped in two classes regarding their genomic organization: tandem repeats and dispersed repeats. In tandem repeats, copies of a short DNA sequence are positioned one after another within the genome, while in dispersed repeats, these copies are randomly distributed. In this review we provide evidence that both tandem and dispersed repeats can have a similar organization, which leads us to suggest an update to their classification based on the sequence features, concretely regarding the presence or absence of retrotransposons/transposon specific domains. In addition, we analyze several studies that show that a repetitive element can be remodeled into repetitive non-coding or coding sequences, suggesting (1) an evolutionary relationship among DNA sequences, and (2) that the evolution of the genomes involved frequent repetitive sequence reshuffling, a process that we have designated as a “DNA remodeling mechanism”. The alternative classification of the repetitive DNA sequences here proposed will provide a novel theoretical framework that recognizes the importance of DNA remodeling for the evolution and plasticity of eukaryotic genomes.


Genome ◽  
2001 ◽  
Vol 44 (4) ◽  
pp. 691-697 ◽  
Author(s):  
Sergei K Svitashev ◽  
David A Somers

The structure of transgene loci in six transgenic allohexaploid oat (Avena sativa L.) lines produced using microprojectile bombardment was characterized using fluorescence in situ hybridization (FISH) on extended DNA fibers (fiber-FISH). The transgene loci in five lines were composed of multiple copies of delivered DNA interspersed with genomic DNA fragments ranging in size from ca. 3 kb to at least several hundred kilobases, and in greater numbers than detected using Southern blot analysis. Although Southern analysis predicted that the transgene locus in one line consisted of long tandem repeats of the delivered DNA, fiber-FISH revealed that the locus actually contained multiple genomic interspersions. These observations indicated that transgene locus size and structure were determined by the number of transgene copies and, possibly to a greater extent, the number and the length of interspersing genomic DNA sequences within the locus. Large genomic interspersions detected in several lines were most likely the products of chromosomal breakage induced either by tissue culture conditions or, more likely, by DNA delivery into the nucleus using microprojectile bombardment. We propose that copies of transgene along with other extrachromosomal DNA fragments are used as patches to repair double-strand breaks (DSBs) in the plant genome resulting in the formation of transgene loci.Key words: genetic transformation, microprojectile bombardment, transgenic oat, FISH, transgene locus structure.


Genetics ◽  
2002 ◽  
Vol 162 (3) ◽  
pp. 1435-1444 ◽  
Author(s):  
Robert M Stupar ◽  
Junqi Song ◽  
Ahmet L Tek ◽  
Zhukuan Cheng ◽  
Fenggao Dong ◽  
...  

Abstract The heterochromatin in eukaryotic genomes represents gene-poor regions and contains highly repetitive DNA sequences. The origin and evolution of DNA sequences in the heterochromatic regions are poorly understood. Here we report a unique class of pericentromeric heterochromatin consisting of DNA sequences highly homologous to the intergenic spacer (IGS) of the 18S•25S ribosomal RNA genes in potato. A 5.9-kb tandem repeat, named 2D8, was isolated from a diploid potato species Solanum bulbocastanum. Sequence analysis indicates that the 2D8 repeat is related to the IGS of potato rDNA. This repeat is associated with highly condensed pericentromeric heterochromatin at several hemizygous loci. The 2D8 repeat is highly variable in structure and copy number throughout the Solanum genus, suggesting that it is evolutionarily dynamic. Additional IGS-related repetitive DNA elements were also identified in the potato genome. The possible mechanism of the origin and evolution of the IGS-related repeats is discussed. We demonstrate that potato serves as an interesting model for studying repetitive DNA families because it is propagated vegetatively, thus minimizing the meiotic mechanisms that can remove novel DNA repeats.


1984 ◽  
Vol 4 (11) ◽  
pp. 2498-2508
Author(s):  
K S Chang ◽  
W E Zimmer ◽  
D J Bergsma ◽  
J B Dodgson ◽  
R J Schwartz

Genes representing six different actin isoforms were isolated from a chicken genomic library. Cloned actin cDNAs as well as tissue-specific mRNAs enriched in different actin species were used as hybridization probes to group individual actin genomic clones by their relative thermal stability. Restriction maps showed that these actin genes were derived from separate and nonoverlapping regions of genomic DNA. Of the six isolated genes, five included sequences from both the 5' and 3' ends of the actin-coding area. Amino acid sequence analysis from both the NH2- and COOH-terminal regions provided for the unequivocal identification of these genes. The striated isoforms were represented by the isolated alpha-skeletal, alpha-cardiac, and alpha-smooth muscle actin genes. The nonmuscle isoforms included the beta-cytoplasmic actin gene and an actin gene fragment which lacked the 5' coding and flanking sequence; presumably, this region of DNA was removed from this gene during construction of the genomic library. Unexpectedly, a third nonmuscle chicken actin gene was found which resembled the amphibian type 5 actin isoform (J. Vandekerckhove, W. W. Franke, and K. Weber, J. Mol. Biol., 152:413-426). This nonmuscle actin type has not been previously detected in warm-blooded vertebrates. We showed that interspersed, repeated DNA sequences closely flanked the alpha-skeletal, alpha-cardiac, beta-, and type 5-like actin genes. The repeated DNA sequences which surround the alpha-skeletal actin-coding regions were not related to repetitious DNA located on the other actin genes. Analysis of genomic DNA blots showed that the chicken actin multigene family was represented by 8 to 10 separate coding loci. The six isolated actin genes corresponded to 7 of 11 genomic EcoRI fragments. Only the alpha-smooth muscle actin gene was shown to be split by an EcoRI site. Thus, in the chicken genome each actin isoform appeared to be encoded by a single gene.


Genome ◽  
1991 ◽  
Vol 34 (5) ◽  
pp. 790-798 ◽  
Author(s):  
H. Aswidinnoor ◽  
R. J. Nelson ◽  
J. F. Dallas ◽  
C. L. McIntyre ◽  
H. Leung ◽  
...  

The value of genome-specific repetitive DNA sequences for use as molecular markers in studying genome differentiation was investigated. Five repetitive DNA sequences from wild species of rice were cloned. Four of the clones, pOm1, pOm4, pOmA536, and pOmPB10, were isolated from Oryza minuta accession 101141 (BBCC genomes), and one clone, pOa237, was isolated from Oryza australiensis accession 100882 (EE genome). Southern blot hybridization to different rice genomes showed strong hybridization of all five clones to O. minuta genomic DNA and no cross hybridization to genomic DNA from Oryza sativa (AA genome). The pOm1 and pOmA536 sequences showed cross hybridization only to all of the wild rice species containing the C genome. However, the pOm4, pOmPB10, and pOa237 sequences showed cross hybridization to O. australiensis genomic DNA in addition to showing hybridization to the O. minuta genomic DNA.Key words: rice, genome-specific repetitive sequences, Oryza.


1984 ◽  
Vol 3 (2) ◽  
pp. 73-81 ◽  
Author(s):  
I. Marta Evans ◽  
John A. Gatehouse ◽  
Grantley W. Lycett ◽  
Donald Boulter

Genome ◽  
1997 ◽  
Vol 40 (3) ◽  
pp. 362-369 ◽  
Author(s):  
J. Lima-Brito ◽  
H. Guedes-Pinto ◽  
G. E. Harrison ◽  
J. S. Heslop-Harrison

Southern and in situ hybridization were used to examine the chromosome constitution, genomic relationships, repetitive DNA sequences, and nuclear architecture in durum wheat × tritordeum hybrids (2n = 5x = 35), where tritordeum is the fertile amphiploid (2n = 6x = 42) between Hordeum chilense and durum wheat. Using in situ hybridization, H. chilense total genomic DNA hybridized strongly to the H. chilense chromosomes and weakly to the wheat chromosomes, which showed some strongly labelled bands. pHcKB6, a cloned repetitive sequence isolated from H. chilense, enabled the unequivocal identification of each H. chilense chromosome at metaphase. Analysis of chromosome disposition in prophase nuclei, using the same probes, showed that the chromosomes of H. chilense origin were in individual domains with only limited intermixing with chromosomes of wheat origin. Six major sites of 18S–26S rDNA genes were detected on the chromosomes of the hybrids. Hybridization to Southern transfers of restriction enzyme digests using genomic DNA showed some variants of tandem repeats, perhaps owing to methylation. Both techniques gave complementary information, extending that available from phenotypic, chromosome morphology, or isozyme analysis, and perhaps are useful for following chromosomes or chromosome segments during further crossing of the lines in plant breeding programs.Key words: In situ hybridization, molecular cytogenetics, plant breeding, Hordeum chilense, Southern hybridization, durum wheat, hybrids.


2016 ◽  
Vol 149 (3) ◽  
pp. 182-190 ◽  
Author(s):  
Marcela B. Pucci ◽  
Patricia Barbosa ◽  
Viviane Nogaroto ◽  
Mara C. Almeida ◽  
Roberto F. Artoni ◽  
...  

Sex chromosome evolution involves the accumulation of repeat sequences such as multigenic families, noncoding repetitive DNA (satellite, minisatellite, and microsatellite), and mobile elements such as transposons and retrotransposons. Most species of Characidium exhibit heteromorphic ZZ/ZW sex chromosomes; the W is characterized by an intense accumulation of repetitive DNA including dispersed satellite DNA sequences and transposable elements. The aim of this study was to analyze the distribution pattern of 18 different tandem repeats, including (GATA)n and (TTAGGG)n, in the genomes of C. zebra and C. gomesi, especially in the C. gomesi W chromosome. In the C. gomesi W chromosome, weak signals were seen for (CAA)10, (CAC)10, (CAT)10, (CGG)10, (GAC)10, and (CA)15 probes. (GA)15 and (TA)15 hybridized to the autosomes but not to the W chromosome. The (GATA)n probe hybridized to the short arms of the W chromosome as well as the (CG)15 probe. The (GATA)n repeat is known to be a protein-binding motif. GATA-binding proteins are necessary for the decondensation of heterochromatic regions that hold coding genes, especially in some heteromorphic sex chromosomes that may keep genes related to oocyte development. The (TAA)10 repeat is accumulated in the entire W chromosome, and this microsatellite accumulation is probably involved in the sex chromosome differentiation process and crossover suppression in C. gomesi. These additional data on the W chromosome DNA composition help to explain the evolution of sex chromosomes in Characidium.


Parasitology ◽  
1991 ◽  
Vol 103 (2) ◽  
pp. 315-319 ◽  
Author(s):  
M. R. Chacon ◽  
R. M. E. Parkhouse ◽  
M. P. Robinson ◽  
P. R. Burrows ◽  
T. Garate

A genomic library of Meloidogyne incognita Race 1 has been prepared in the bacteriophage λgt10 and screened for specific DNA sequences by hybridization with radio-isotope labelled total genomic DNA from a number of Meloidogyne species. One clone isolated (MR1#15), although not totally species specific, clearly showed preferential hybridization to M. incognita. Following subcloning and sequencing of the 255 bp insert, four stretches of the sequence corresponding to oligonucleotides of approximately equal length (~60 bp) were synthesized and examined for specificity. One of them, MR1#15.2, showed the necessary specificity to be used as a diagnostic tool.


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