Molecular characterization and chromosome location of repeated DNA sequences in Hordeum species and in the amphiploid tritordeum (×Tritordeum Ascherson et Graebner)

Genome ◽  
1995 ◽  
Vol 38 (5) ◽  
pp. 850-857 ◽  
Author(s):  
Esther Ferrer ◽  
Yolanda Loarce ◽  
Gregorio Hueros
Keyword(s):  
In Situ Hybridization ◽  
Dna Sequences ◽  
Diploid Species ◽  
Repeated Sequences ◽  
Hordeum Chilense ◽  
Repeated Dna ◽  
Repeated Dna Sequences ◽  
In Situ Experiments ◽  
Basic Genome

Genomic DNA from 19 species and subspecies representing the four basic genomes (H, I, X, and Y) of Hordeum was restricted with HaeIII and hybridized with two repeated DNA sequences of Hordeum chilense. The potential use of repeated sequences in ascertaining genomic affinities within the genus Hordeum was studied by comparing restriction fragment patterns. The study demonstrated the following: (i) species that shared a basic genome showed more similar hybridization fragment patterns than species with different genomes, whether with pHchl or pHch3; (ii) hybridization with pHchl revealed the presence of certain fragments limited to the species with a H genome; and (iii) the alloploid nature of species like H. jubatum was confirmed. The chromosomal distribution of the two repeated sequences was studied in species representing each basic genome and in the amphiploid tritordeum using fluorescent in situ hybridization. No interspecific differences were found between the diploid species. In situ experiments indicated the alloploid nature of H. depressum. Both sequences allow H. chilense chromatin to be distinguished from wheat chromosomes in tritordeum.Key words: repeated DNA sequences; in situ hybridization, Hordeum, tritordeum.

The molecular structure, chromosomal organization, and interspecies distribution of a family of tandemly repeated DNA sequences of Antirrhinum majus L.

Genome ◽  
1996 ◽  
Vol 39 (2) ◽  
pp. 243-248 ◽  
Author(s):  
Thomas Schmidt ◽  
Jörg Kudla
Keyword(s):  
In Situ Hybridization ◽  
Dna Sequences ◽  
Satellite Dna ◽  
Antirrhinum Majus ◽  
Repeated Dna ◽  
Satellite Dnas ◽  
Repeated Dna Sequences ◽  
The North ◽  
Tandemly Repeated Dna

Monomers of a major family of tandemly repeated DNA sequences of Antirrhinum majus have been cloned and characterized. The repeats are 163–167 bp long, contain on average 60% A + T residues, and are organized in head-to-tail orientation. According to site-specific methylation differences two subsets of repeating units can be distinguished. Fluorescent in situ hybridization revealed that the repeats are localized at centromeric regions of six of the eight chromosome pairs of A. majus with substantial differences in array size. The monomeric unit shows no homologies to other plant satellite DNAs. The repeat exists in a similar copy number and conserved size in the genomes of six European species of the genus Antirrhinum. Tandemly repeated DNA sequences with homology to the cloned monomer were also found in the North American section Saerorhinum, indicating that this satellite DNA might be of ancient origin and was probably already present in the ancestral genome of both sections. Key words : Antirrhinum majus, satellite DNA, repetitive DNA, methylation, in situ hybridization.

Genomic organization, sequence interrelationship, and physical localization using in situ hybridization of two tandemly repeated DNA sequences in the genus Olea

Genome ◽  
1998 ◽  
Vol 41 (4) ◽  
pp. 527-534 ◽  
Author(s):  
Andreas Katsiotis ◽  
Marianna Hagidimitriou ◽  
Alexandra Douka ◽  
Polydefkis Hatzopoulos
Keyword(s):  
In Situ Hybridization ◽  
Dna Sequences ◽  
Genomic Library ◽  
Repeat Sequence ◽  
Repeated Dna ◽  
Repeated Dna Sequences ◽  
Young Leaves ◽  
Partial Genomic Library ◽  
Tandemly Repeated Dna

Two tandemly repeated DNA sequences, the 81-bp family and pOS218, have been isolated from a Sau3AI Olea europaea ssp. sativa partial genomic library. Sequencing of the 81-bp element showed the monomer to be between 78 and 84 bases long and to contain 51-58% adenine and thymidine residues. Comparison between the monomers revealed heterogeneity of the sequence primary structure. The clone pOS218 is 218 bases long, and sequence comparison between the two elements revealed that an internal region of the pOS218 repeated DNA sequence had 79% homology to the 81 bp repeat sequence. A breakage-reunion mechanism, involving the CAAAA sequence, could be responsible for the derivation of pOS218 from the 81 bp family element. By using double target in situ hybridization, co-localization of the two sequences on Olea chromosomes was observed. The sequences were present at DAPI stained heterochromatic regions, as major or minor sites having a subtelomeric or interstitial location. Methylation studies using two sets of isoschizomers, Sau3AI-MboI and MspI-HpaII, demonstrated that most cytosine residues in the GATC sites and the internal cytosine in the CCGG sites of both elements were methylated in O. europaea ssp. sativa. No major difference in methylation was apparent between DNA extracted from young leaves or from callus of O. europaea ssp.sativa. Both elements are also present in Olea chrysophylla, Olea oleaster, and Olea africana, but are absent from other Oleaceae genera, including Phillyrea, Forsythia, Ligustrum, Parasyringa, and Jasminum.Key words: in situ hybridization, methylation, Oleaceae, phylogenetic relationships, repeated sequences.

Molecular cytogenetic analysis of durum wheat × tritordeum hybrids

Genome ◽  
1997 ◽  
Vol 40 (3) ◽  
pp. 362-369 ◽  
Author(s):  
J. Lima-Brito ◽  
H. Guedes-Pinto ◽  
G. E. Harrison ◽  
J. S. Heslop-Harrison
Keyword(s):  
In Situ Hybridization ◽  
Plant Breeding ◽  
Durum Wheat ◽  
Dna Sequences ◽  
Genomic Dna ◽  
Tandem Repeats ◽  
Nuclear Architecture ◽  
Molecular Cytogenetics ◽  
Hordeum Chilense

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.

scholarly journals Functional analysis of a centromere from fission yeast: a role for centromere-specific repeated DNA sequences.

1990 ◽  
Vol 10 (5) ◽  
pp. 1863-1872 ◽  
Author(s):  
L Clarke ◽  
M P Baum
Keyword(s):  
Dna Sequences ◽  
Inverted Repeat ◽  
Repeated Sequence ◽  
Repeated Sequences ◽  
Central Core ◽  
Repeated Dna ◽  
Inverted Repeat Region ◽  
Repeated Dna Sequences ◽  
Centromere Function ◽  
Chromosome Ii

A circular minichromosome carrying functional centromere sequences (cen2) from Schizosaccharomyces pombe chromosome II behaves as a stable, independent genetic linkage group in S. pombe. The cen2 region was found to be organized into four large tandemly repeated sequence units which span over 80 kilobase pairs (kb) of untranscribed DNA. Two of these units occurred in a 31-kb inverted repeat that flanked a 7-kb central core of nonhomology. The inverted repeat region had centromere function, but neither the central core alone nor one arm of the inverted repeat was functional. Deletion of a portion of the repeated sequences that flank the central core had no effect on mitotic segregation functions or on meiotic segregation of a minichromosome to two of the four haploid progeny, but drastically impaired centromere-mediated maintenance of sister chromatid attachment in meiosis I. This requirement for centromere-specific repeated sequences could not be satisfied by introduction of random DNA sequences. These observations suggest a function for the heterochromatic repeated DNA sequences found in the centromere regions of higher eucaryotes.

Distribution of highly repeated DNA sequences in species of the genus Secale

Genome ◽  
1997 ◽  
Vol 40 (3) ◽  
pp. 309-317 ◽  
Author(s):  
Angeles Cuadrado ◽  
Nicolás Jouve
Keyword(s):  
In Situ Hybridization ◽  
Fluorescence In Situ Hybridization ◽  
Repetitive Dna ◽  
Dna Sequences ◽  
5S Rdna ◽  
Nucleotide Sequences ◽  
Repeated Dna ◽  
Accurate Identification ◽  
Highly Repetitive Dna

The presence and distribution of the most important highly repetitive DNA sequences of rye in cultivated and wild species of the genus Secale were investigated using fluorescence in situ hybridization. Accurate identification of individual chromosomes in the most commonly recognized species or subspecies of the genus Secale (S. cereale, S. ancestrale, S. segetale, S. afghanicum, S. dighoricum, S. montanum, S. montanum ssp. kuprijanovii, S. africanum, S. anatolicum, S. vavilovii, and S. silvestre) was achieved using three highly repetitive rye DNA sequences (probes pSc119.2, pSc74, and pSc34) and the 5S ribosomal DNA sequence pTa794. It is difficult to superimpose trends in the complexity of repetitive DNA during the evolution of the genus on conclusions from other cytogenetic and morphological assays. However, there are two clear groups. The first comprises the self-pollinated annuals S. silvestre and S. vavilovii that have few repeated nucleotide sequences of the main families of 120 and 480 bp. The second group presents amplification and interstitialization of the repeated nucleotide sequences and includes the perennials S. montanum, S. anatolicum, S. africanum, and S. kuprijanovii, as well as the annual and open-pollinated species S. cereale and its related weedy forms. The appearance of a new locus for 5S rRNA in S. cereale and S. ancestrale suggests that cultivated ryes evolved from this wild weedy species.Key words: rye, repeated nucleotide sequence, 5S rDNA, fluorescence in situ hybridization, FISH.

scholarly journals A sister-strand exchange mechanism for recA-independent deletion of repeated DNA sequences in Escherichia coli.

Genetics ◽  
1993 ◽  
Vol 135 (3) ◽  
pp. 631-642 ◽  
Author(s):  
S T Lovett ◽  
P T Drapkin ◽  
V A Sutera ◽  
T J Gluckman-Peskind
Keyword(s):  
Escherichia Coli ◽  
Dna Sequences ◽  
Repeated Sequences ◽  
Repeated Dna ◽  
Repeated Dna Sequences ◽  
E Coli ◽  
Deletion Formation ◽  
Dna Strands

Abstract In the genomes of many organisms, deletions arise between tandemly repeated DNA sequences of lengths ranging from several kilobases to only a few nucleotides. Using a plasmid-based assay for deletion of a 787-bp tandem repeat, we have found that a recA-independent mechanism contributes substantially to the deletion process of even this large region of homology. No Escherichia coli recombination gene tested, including recA, had greater than a fivefold effect on deletion rates. The recA-independence of deletion formation is also observed with constructions present on the chromosome. RecA promotes synapsis and transfer of homologous DNA strands in vitro and is indispensable for intermolecular recombination events in vivo measured after conjugation. Because deletion formation in E. coli shows little or no dependence on recA, it has been assumed that homologous recombination contributes little to the deletion process. However, we have found recA-independent deletion products suggestive of reciprocal crossovers when branch migration in the cell is inhibited by a ruvA mutation. We propose a model for recA-independent crossovers between replicating sister strands, which can also explain deletion or amplification of repeated sequences. We suggest that this process may be initiated as post-replicational DNA repair; subsequent strand misalignment at repeated sequences leads to genetic rearrangements.

scholarly journals THE EVOLUTION OF RESTRICTED RECOMBINATION AND THE ACCUMULATION OF REPEATED DNA SEQUENCES

Genetics ◽  
1986 ◽  
Vol 112 (4) ◽  
pp. 947-962 ◽  
Author(s):  
Brian Charlesworth ◽  
Charles H Langley ◽  
Wolfgang Stephan
Keyword(s):  
Dna Sequences ◽  
Single Copy ◽  
Repeated Sequences ◽  
Stabilizing Selection ◽  
Crossing Over ◽  
Repeated Dna ◽  
Repeated Dna Sequences ◽  
Unequal Exchange ◽  
Single Copy Sequence ◽  
Speed Up

ABSTRACT We suggest hypotheses to account for two major features of chromosomal organization in higher eukaryotes. The first of these is the general restriction of crossing over in the neighborhood of centromeres and telomeres. We propose that this is a consequence of selection for reduced rates of unequal exchange between repeated DNA sequences for which the copy number is subject to stabilizing selection: microtubule binding sites, in the case of centromeres, and the short repeated sequences needed for terminal replication of a linear DNA molecule, in the case of telomeres. An association between proximal crossing over and nondisjunction would also favor the restriction of crossing over near the centromere. The second feature is the association between highly repeated DNA sequences of no obvious functional significance and regions of restricted crossing over. We show that highly repeated sequences are likely to persist longest (over evolutionary time) when crossing over is infrequent. This is because unequal exchange among repeated sequences generates single copy sequences, and a population that becomes fixed for a single copy sequence by drift remains in this state indefinitely (in the absence of gene amplification processes). Increased rates of exchange thus speed up the process of stochastic loss of repeated sequences.

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