Distribution of a Secale cereale DNA repeat sequence among 25 Hordeum species

Genome ◽  
1989 ◽  
Vol 32 (3) ◽  
pp. 383-388 ◽  
Author(s):  
P. K. Gupta ◽  
G. Fedak ◽  
S. J. Molnar ◽  
Roger Wheatcroft
Keyword(s):  
Dna Sequences ◽  
Secale Cereale ◽  
Dna Hybridization ◽  
Interspecific Variation ◽  
Repeat Sequence ◽  
Species Variation ◽  
Repeated Dna ◽  
Repeat Units ◽  
Dna Repeat ◽  
Hordeum Species

DNA of 61 accessions representing 25 Hordeum species was tested for homology to a highly repeated 120-bp sequence from Secale cereale (rye). Homology to the probe (pSC119) was detected in dot blots of all species except H. vulgare (cultivated barley) and its related species, H. agriocrithon and H. spontaneum. Hybridization patterns of Southern blots of restriction fragments demonstrated both intraspecific and interspecific variation in the organization of complex units of DNA having homology to the probe. For eight species, digestion of the DNA with BamHI gave ladder patterns characteristic of tandem arrays of 120-bp repeat units. For EcoRI, HindIII, and SacI digests, the hybridization patterns appeared to be highly conserved in the section Hordeum, except those for H. bulbosum, which were unique. A further set of patterns for these three enzymes was common among the remaining species of the genus. Thus, DNA hybridization with pSC119 generally gave patterns consistent with the current taxonomy of Hordeum species, except that H. bulbosum and H. vulgare were not shown to be closely related.Key words: Hordeum, repeated DNA sequences, pSC119, species variation.

scholarly journals INDUCTION OF INTRACHROMOSOMAL RECOMBINATION IN YEAST BY INHIBITION OF THYMIDYLATE BIOSYNTHESIS

Genetics ◽  
1986 ◽  
Vol 114 (2) ◽  
pp. 375-392
Author(s):  
B A Kunz ◽  
G R Taylor ◽  
R H Haynes
Keyword(s):  
Gene Conversion ◽  
Dna Sequences ◽  
Dna Hybridization ◽  
Crossing Over ◽  
Repeated Dna ◽  
Yeast Saccharomyces Cerevisiae ◽  
Haploid Strain ◽  
Reciprocal Exchange ◽  
Coli Plasmid ◽  
Antifolate Drugs

ABSTRACT The biosynthesis of thymidylate in the yeast Saccharomyces cerevisiae can be inhibited by antifolate drugs. We have found that antifolate treatment enhances the formation of leucine prototrophs in a haploid strain of yeast carrying, on the same chromosome, two different mutant leu2 alleles separated by Escherichia coli plasmid sequences. That this effect is a consequence of thymine nucleotide depletion was verified by the finding that provision of exogenous thymidylate eliminates the increased production of Leu+ colonies. DNA hybridization analysis revealed that recombination, including reciprocal exchange, gene conversion and unequal sister-chromatid crossing over, between the duplicated genes gave rise to the induced Leu+ segregants. Although gene conversion unaccompanied by crossing over was responsible for the major fraction of leucine prototrophs, events involving reciprocal exchange exhibited the largest increase in frequency. These data show that recombination is induced between directly repeated DNA sequences under conditions of thymine nucleotide depletion. In addition, the results of this and previous studies are consistent with the possibility that inhibition of thymidylate biosynthesis in yeast may create a metabolic condition that provokes all forms of mitotic recombination.

Nonrandom localization of recombination events in human alpha satellite repeat unit variants: implications for higher-order structural characteristics within centromeric heterochromatin

1993 ◽  
Vol 13 (10) ◽  
pp. 6520-6529
Author(s):  
P E Warburton ◽  
J S Waye ◽  
H F Willard
Keyword(s):  
Dna Sequences ◽  
Concerted Evolution ◽  
Repeat Unit ◽  
Higher Order ◽  
Centromeric Heterochromatin ◽  
Alpha Satellite ◽  
Repeated Dna ◽  
Satellite Repeat ◽  
Repeat Units ◽  
Tandemly Repeated Dna

Tandemly repeated DNA families appear to undergo concerted evolution, such that repeat units within a species have a higher degree of sequence similarity than repeat units from even closely related species. While intraspecies homogenization of repeat units can be explained satisfactorily by repeated rounds of genetic exchange processes such as unequal crossing over and/or gene conversion, the parameters controlling these processes remain largely unknown. Alpha satellite DNA is a noncoding tandemly repeated DNA family found at the centromeres of all human and primate chromosomes. We have used sequence analysis to investigate the molecular basis of 13 variant alpha satellite repeat units, allowing comparison of multiple independent recombination events in closely related DNA sequences. The distribution of these events within the 171-bp monomer is nonrandom and clusters in a distinct 20- to 25-bp region, suggesting possible effects of primary sequence and/or chromatin structure. The position of these recombination events may be associated with the location within the higher-order repeat unit of the binding site for the centromere-specific protein CENP-B. These studies have implications for the molecular nature of genetic recombination, mechanisms of concerted evolution, and higher-order structure of centromeric heterochromatin.

scholarly journals Nonrandom localization of recombination events in human alpha satellite repeat unit variants: implications for higher-order structural characteristics within centromeric heterochromatin.

1993 ◽  
Vol 13 (10) ◽  
pp. 6520-6529 ◽  
Author(s):  
P E Warburton ◽  
J S Waye ◽  
H F Willard
Keyword(s):  
Dna Sequences ◽  
Concerted Evolution ◽  
Repeat Unit ◽  
Higher Order ◽  
Centromeric Heterochromatin ◽  
Alpha Satellite ◽  
Repeated Dna ◽  
Satellite Repeat ◽  
Repeat Units ◽  
Tandemly Repeated Dna

Tandemly repeated DNA families appear to undergo concerted evolution, such that repeat units within a species have a higher degree of sequence similarity than repeat units from even closely related species. While intraspecies homogenization of repeat units can be explained satisfactorily by repeated rounds of genetic exchange processes such as unequal crossing over and/or gene conversion, the parameters controlling these processes remain largely unknown. Alpha satellite DNA is a noncoding tandemly repeated DNA family found at the centromeres of all human and primate chromosomes. We have used sequence analysis to investigate the molecular basis of 13 variant alpha satellite repeat units, allowing comparison of multiple independent recombination events in closely related DNA sequences. The distribution of these events within the 171-bp monomer is nonrandom and clusters in a distinct 20- to 25-bp region, suggesting possible effects of primary sequence and/or chromatin structure. The position of these recombination events may be associated with the location within the higher-order repeat unit of the binding site for the centromere-specific protein CENP-B. These studies have implications for the molecular nature of genetic recombination, mechanisms of concerted evolution, and higher-order structure of centromeric heterochromatin.

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.

Two repeated DNA sequences from the heterochromatic regions of rye (Secale cereale) chromosomes

Chromosoma ◽  
1981 ◽  
Vol 84 (2) ◽  
pp. 265-277 ◽  
Author(s):  
R. Appels ◽  
E. S. Dennis ◽  
D. R. Smyth ◽  
W. J. Peacock
Keyword(s):  
Dna Sequences ◽  
Secale Cereale ◽  
Repeated Dna ◽  
Repeated Dna Sequences

Polymorphism in ribosomal DNA repeat units of 12 Hordeum species

Genome ◽  
1989 ◽  
Vol 32 (6) ◽  
pp. 1124-1127 ◽  
Author(s):  
Stephen J. Molnar ◽  
George Fedak
Keyword(s):  
Ribosomal Dna ◽  
Repeat Unit ◽  
Unit Length ◽  
Intergenic Spacer ◽  
Rdna Repeat ◽  
Repeat Units ◽  
Dna Repeat ◽  
Rdna Repeat Unit ◽  
Bamhi Restriction Site ◽  
Hordeum Species

Total genomic DNA was isolated from leaves of individual accessions of 12 Hordeum species. SacI, HindIII, and BamHI restriction fragments hybridizing to the wheat rDNA probe pTA71 were compared. Thirteen rDNA repeat unit length variants were recovered, which combined to produce 11 distinct phenotypes. All rDNA repeat units had two SacI sites and no HindIII sites. The rDNA repeat units of H. secalinum, H. hrasdanicum, and H. distichum all had 3 BamHI sites, but in different configurations. The rDNA repeat units of the other species had at least 4 BamHI sites. Ladders of small hybridizing fragments in 8 of 9 of the latter accessions indicated the presence of occasional BamHI sites in some subrepeats within the intergenic spacer regions of the rDNA repeat units. Different distributions of BamHI restriction site maps within the Hordeum sections strengthen the concept of using variation in rDNA restriction sites as a taxonomic character.Key words: Hordeum, ribosomal DNA, polymorphism.

Physical mapping of plant DNA sequences by simultaneous in situ hybridization of two differently labelled fluorescent probes

Genome ◽  
1991 ◽  
Vol 34 (3) ◽  
pp. 329-333 ◽  
Author(s):  
I. J. Leitch ◽  
A. R. Leitch ◽  
J. S. Heslop-Harrison
Keyword(s):  
In Situ Hybridization ◽  
Physical Mapping ◽  
Dna Sequences ◽  
Secale Cereale ◽  
Repeat Sequence ◽  
Tandem Repeat Sequence ◽  
Plant Dna ◽  
Multiple Labelling ◽  
Ribosomal Dna Sequence

Two haptens, biotin and digoxigenin, were used to label two highly repetitive plant DNA sequences: pTa71 (a clone containing a ribosomal DNA sequence from wheat, Triticum aestivum) and pSc119.2 (a clone containing a 120-bp tandem repeat sequence from rye, Secale cereale). These probes were simultaneously localized by in situ hybridization on chromosome spreads of rye, Secale cereale cv. Petkus Spring. The ability to localize two sequences simultaneously will be of major importance for physically ordering DNA sequences along plant chromosomes.Key words: physical mapping, DNA–DNA in situ hybridization, Secale, fluorescent mapping, multiple labelling.

scholarly journals Molecular Characterization of a Family of Tandemly Repeated DNA Sequences, TR-1, in Heterochromatic Knobs of Maize and Its Relatives

Genetics ◽  
2003 ◽  
Vol 164 (3) ◽  
pp. 1087-1097 ◽  
Author(s):  
F C Hsu ◽  
C J Wang ◽  
C M Chen ◽  
H Y Hu ◽  
C C Chen
Keyword(s):  
Dna Sequences ◽  
Tandem Repeats ◽  
B Chromosome ◽  
Repeated Dna ◽  
Sequence Comparisons ◽  
Repeat Units ◽  
Entire Sequence ◽  
Single Sequence

Abstract Two families of tandem repeats, 180-bp and TR-1, have been found in the knobs of maize. In this study, we isolated 59 clones belonging to the TR-1 family from maize and teosinte. Southern hybridization and sequence analysis revealed that members of this family are composed of three basic sequences, A (67 bp); B (184 bp) or its variants B′ (184 bp), 2/3B (115 bp), 2/3B′ (115 bp); and C (108 bp), which are arranged in various combinations to produce repeat units that are multiples of ∼180 bp. The molecular structure of TR-1 elements suggests that: (1) the B component may evolve from the 180-bp knob repeat as a result of mutations during evolution; (2) B′ may originate from B through lateral amplification accompanied by base-pair changes; (3) C plus A may be a single sequence that is added to B and B′, probably via nonhomologous recombination; and (4) 69 bp at the 3′ end of B or B′, and the entire sequence of C can be removed from the elements by an unknown mechanism. Sequence comparisons showed partial homologies between TR-1 elements and two centromeric sequences (B repeats) of the supernumerary B chromosome. This result, together with the finding of other investigators that the B repeat is also fragmentarily homologous to the 180-bp repeat, suggests that the B repeat is derived from knob repeats in A chromosomes, which subsequently become structurally modified. Fluorescence in situ hybridization localized the B repeat to the B centromere and the 180-bp and TR-1 repeats to the proximal heterochromatin knob on the B chromosome.

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