An AT-rich satellite DNA sequence, E180, in alfalfa (Medicago sativa)

Genome ◽  
1993 ◽  
Vol 36 (3) ◽  
pp. 427-432 ◽  
Author(s):  
X. Xia ◽  
L. Erickson
Keyword(s):  
Medicago Sativa ◽  
Dna Sequence ◽  
Repetitive Dna ◽  
Dna Sequences ◽  
Satellite Dna ◽  
Nuclear Dna ◽  
Consensus Sequence ◽  
Repeated Dna Sequence ◽  
Dna Fragment ◽  
High Degree

A DNA fragment of ~750 bp was cloned from EcoRI-digested nuclear DNA of alfalfa (Medicago sativa). Southern blot and sequence analysis showed that the cloned DNA fragment represents a tetramer of a highly tandemly repeated DNA sequence of 185–188 bp (E180). The consensus sequence deduced from the four repeating units is 189 bp in length with an AT content of 67%. The copy number of the satellite DNA was estimated to be ~1.8 × 105 per genome and constitutes about 1% of the alfalfa genome. Sequence comparison revealed no identity to any repetitive DNA sequences that have been published to date. Digestion with HpaII and MspI indicated a high degree of methylation at the internal C of the restriction site CCGG within E180.Key words: alfalfa, Medicago, repetitive DNA sequence, satellite DNA.

A species-specific satellite DNA from the entomopathogenic nematode Heterorhabditis indicus

Genome ◽  
1998 ◽  
Vol 41 (2) ◽  
pp. 148-153 ◽  
Author(s):  
Monique Abadon ◽  
Eric Grenier ◽  
Christian Laumond ◽  
Pierre Abad
Keyword(s):  
Dna Sequence ◽  
Satellite Dna ◽  
Tandem Repeats ◽  
Sequence Data ◽  
Entomopathogenic Nematode ◽  
Consensus Sequence ◽  
Repeated Sequence ◽  
Nucleotide Sequence Analysis ◽  
Specific Sequence ◽  
Species Specific

An AluI satellite DNA family has been cloned from the entomopathogenic nematode Heterorhabditis indicus. This repeated sequence appears to be an unusually abundant satellite DNA, since it constitutes about 45% of the H. indicus genome. The consensus sequence is 174 nucleotides long and has an A + T content of 56%, with the presence of direct and inverted repeat clusters. DNA sequence data reveal that monomers are quite homogeneous. Such homogeneity suggests that some mechanism is acting to maintain the homogeneity of this satellite DNA, despite its abundance, or that this repeated sequence could have appeared recently in the genome of H. indicus. Hybridization analysis of genomic DNAs from different Heterorhabditis species shows that this satellite DNA sequence is specific to the H. indicus genome. Considering the species specificity and the high copy number of this AluI satellite DNA sequence, it could provide a rapid and powerful tool for identifying H. indicus strains.Key words: AluI repeated DNA, tandem repeats, species-specific sequence, nucleotide sequence analysis.

Similar 150-kilobase DNA sequences are amplified in independently derived methotrexate-resistant Chinese hamster cells

1985 ◽  
Vol 5 (4) ◽  
pp. 619-627
Author(s):  
M Montoya-Zavala ◽  
J L Hamlin
Keyword(s):  
Dna Sequence ◽  
Cell Lines ◽  
Dihydrofolate Reductase ◽  
Dna Sequences ◽  
Consensus Sequence ◽  
Chinese Hamster ◽  
Ovary Cell ◽  
Chinese Hamster Cells ◽  
Reductase Gene ◽  
Reductase Domain

We have isolated overlapping recombinant cosmids that represent 150 kilobases of contiguous DNA sequence from the amplified dihydrofolate reductase domain of a methotrexate-resistant Chinese hamster ovary cell line (CHOC 400). This sequence includes the 25-kilobase dihydrofolate reductase gene and an origin of DNA synthesis. Eight cosmids that span this domain have been utilized as radioactive hybridization probes to analyze the similarities among the dihydrofolate reductase amplicons in four independently derived methotrexate-resistant Chinese hamster cell lines. We have observed no significant differences among the four cell lines within the 150-kilobase DNA sequence that we have examined, except for polymorphisms that result from the amplification of one or the other of two possible alleles of the dihydrofolate reductase domain. We also show that the restriction patterns of the amplicons in these four resistant cell lines are virtually identical to that of the corresponding, unamplified sequence in drug-susceptible parental cells. Furthermore, measurements of the relative copy numbers of fragments from widely separated regions of the amplicon suggest that all fragments in this 150-kilobase region may be amplified in unison. Our data show that in methotrexate-resistant Chinese hamster cells, the amplified unit is large relative to the dihydrofolate reductase gene itself. Furthermore, within the 150-kilobase amplified consensus sequence that we have examined, significant rearrangements do not seem to occur during the amplification process.

Genomic relationships between Dasypyrum villosum (L.) Candargy and D. hordeaceum (Cosson et Durieu) Candargy

Genome ◽  
1996 ◽  
Vol 39 (1) ◽  
pp. 83-92 ◽  
Author(s):  
A. Blanco ◽  
R. Simeone ◽  
P. Resta ◽  
C. De Pace ◽  
V. Delre ◽  
...  
Keyword(s):  
Dna Sequence ◽  
Dna Sequences ◽  
Phylogenetic Relationships ◽  
Single Copy ◽  
Dasypyrum Villosum ◽  
Repeated Dna ◽  
Esterase Isozyme ◽  
Dot Blot ◽  
Genomic Relationships ◽  
Repeated Dna Sequence

The origin and genomic constitution of the tetraploid perennial species Dasypyrum hordeaceum (2n = 4x = 28) and its phylogenetic relationships with the annual diploid Dasypyrum villosum (2n = 2x = 14) have been investigated by comparing the two genomes using different methods. There is no apparent homology between the conventional or Giemsa C-banded karyotypes of the two Dasypyrum species, nor can the karyotype of D. hordeaceum be split up into two similar sets. Polymorphism within several chromosome pairs was observed in both karyotypes. Cytophotometric determinations of the Feulgen–DNA absorptions showed that the genome size of D. hordeaceum was twice as large as that of D. villosum. Both the cross D. villosum × D. hordeaceum (crossability rate 12.1%) and the reciprocal cross (crossability rate 50.7%) produced plump seeds. Only those from the former cross germinated, producing sterile plants with a phenotype that was intermediate between those of the parents. In these hybrids (2n = 21), an average of 13.77 chromosomes per cell paired at meiotic metaphase I. Trivalents were only rarely observed. Through dot-blot hybridizations, a highly repeated DNA sequence of D. villosum was found not to be represented in the genome of D. hordeaceum. By contrast, very similar restriction patterns were observed when a low-repeated DNA sequence or different single-copy sequences of D. villosum or two sequences in the plastidial DNA of rice were hybridized to Southern blots of the genomic DNAs of the two Dasypyrum species digested with different restriction endonucleases. By analyzing glutamic-oxaloacetic-transaminase, superoxide dismutase, alcohol dehydrogenase, and esterase isozyme systems, it was shown that both Dasypyrum species shared the same phenotypes, which differed from those found in hexaploid wheat. In situ hybridizations using DNA sequences encoding gliadins showed that these genes were located close to the centromere of three pairs of D. villosum chromosomes and that they had the same locations in six pairs of D. hordeaceum chromosomes. We conclude that the autoploid origin of D. hordeaceum from D. villosum, which cannot be defended on the basis of chromosomal traits, is suggested by the other findings obtained by comparing the two genomes. Key words : Dasypyrum hordeaceum, Dasypyrum villosum, phylogenetic relationships.

scholarly journals DNA Sequence and Functional Analysis of Homologous ARS Elements of Saccharomyces cerevisiae and S. carlsbergensis

Genetics ◽  
1999 ◽  
Vol 152 (3) ◽  
pp. 943-952
Author(s):  
James F Theis ◽  
Chen Yang ◽  
Christopher B Schaefer ◽  
Carol S Newlon
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Sequence ◽  
Dna Sequences ◽  
Consensus Sequence ◽  
Chromosomal Dna ◽  
Functional Elements ◽  
Sequence Comparisons ◽  
Cis Acting ◽  
Homologous Sequences ◽  
Ars Elements

Abstract ARS elements of Saccharomyces cerevisiae are the cis-acting sequences required for the initiation of chromosomal DNA replication. Comparisons of the DNA sequences of unrelated ARS elements from different regions of the genome have revealed no significant DNA sequence conservation. We have compared the sequences of seven pairs of homologous ARS elements from two Saccharomyces species, S. cerevisiae and S. carlsbergensis. In all but one case, the ARS308-ARS308carl pair, significant blocks of homology were detected. In the cases of ARS305, ARS307, and ARS309, previously identified functional elements were found to be conserved in their S. carlsbergensis homologs. Mutation of the conserved sequences in the S. carlsbergensis ARS elements revealed that the homologous sequences are required for function. These observations suggested that the sequences important for ARS function would be conserved in other ARS elements. Sequence comparisons aided in the identification of the essential matches to the ARS consensus sequence (ACS) of ARS304, ARS306, and ARS310carl, though not of ARS310.

scholarly journals Conversion of Genomic DNA to Proxy Constructs Suitable for Accurate Nanopore Sequencing

2015 ◽  
Author(s):  
Dimitra Tsavachidou
Keyword(s):  
Dna Sequence ◽  
Genomic Dna ◽  
Average Length ◽  
Consensus Sequence ◽  
Whole Genome ◽  
Nanopore Sequencing ◽  
Ion Torrent ◽  
Dna Molecules ◽  
Dna Fragment ◽  
Genome Level

AbstractNanopore sequencing at single-base resolution is challenging. There are developing technologies to convert DNA molecules to expanded constructs. Such constructs can be sequenced by nanopores in place of the original DNA molecules. We present a novel method for converting genomic DNA to expanded constructs (“proxies”) with 99.67% accuracy. Our method “reads” each base in each DNA fragment and appends an oligonucleotide to the DNA fragment after each base “reading”. Each appended oligonucleotide represents a specific base type, so that the proxy construct consisting of all the appended oligonucleotides faithfully represents the original DNA sequence. We generated proxies for genomic DNA and confirmed the identities of both the proxies and their corresponding original DNA sequences by performing sequencing using Ion Torrent sequencer.Conversion to proxies had only 0.33% raw error rate. Errors were: 93.96% deletions, 5.29% insertions, and 0.74% substitutions. The longest sequenced proxy was 170 bases, corresponding to a 17-base original DNA sequence. The short length of the detected proxies reflected restrictions imposed by Ion Torrent’s short reads and was not caused by limitations of our method. The consensus sequence built by using proxies alone (average length: 120 bases; corresponding to original sequences with average length 12 bases) covered 55% of the reference genome with 100% accuracy, and outperformed the Ion Torrent sequencing of the corresponding original DNA fragments in terms of accuracy, coverage and number of aligned sequences. Data and other materials can be found at http://www.vastogen.com/data.html. This proof-of-concept experiment demonstrates highly accurate proxy construction at the whole genome level. To our knowledge, this is the first demonstrated construction of expanded versions of DNA at the whole genome level.

scholarly journals Comparative analysis of morabine grasshopper genomes reveals highly abundant transposable elements and rapidly proliferating satellite DNA repeats

BMC Biology ◽  
2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Octavio M. Palacios-Gimenez ◽  
Julia Koelman ◽  
Marc Palmada-Flores ◽  
Tessa M. Bradford ◽  
Karl K. Jones ◽  
...  
Keyword(s):  
Transposable Elements ◽  
Genome Evolution ◽  
Repetitive Dna ◽  
Dna Sequences ◽  
Satellite Dna ◽  
Species Complex ◽  
Repetitive Dna Sequences ◽  
Dna Repeats ◽  
Large Genome ◽  
Chromosomal Races

Abstract Background Repetitive DNA sequences, including transposable elements (TEs) and tandemly repeated satellite DNA (satDNAs), collectively called the “repeatome”, are found in high proportion in organisms across the Tree of Life. Grasshoppers have large genomes, averaging 9 Gb, that contain a high proportion of repetitive DNA, which has hampered progress in assembling reference genomes. Here we combined linked-read genomics with transcriptomics to assemble, characterize, and compare the structure of repetitive DNA sequences in four chromosomal races of the morabine grasshopper Vandiemenella viatica species complex and determine their contribution to genome evolution. Results We obtained linked-read genome assemblies of 2.73–3.27 Gb from estimated genome sizes of 4.26–5.07 Gb DNA per haploid genome of the four chromosomal races of V. viatica. These constitute the third largest insect genomes assembled so far. Combining complementary annotation tools and manual curation, we found a large diversity of TEs and satDNAs, constituting 66 to 75% per genome assembly. A comparison of sequence divergence within the TE classes revealed massive accumulation of recent TEs in all four races (314–463 Mb per assembly), indicating that their large genome sizes are likely due to similar rates of TE accumulation. Transcriptome sequencing showed more biased TE expression in reproductive tissues than somatic tissues, implying permissive transcription in gametogenesis. Out of 129 satDNA families, 102 satDNA families were shared among the four chromosomal races, which likely represent a diversity of satDNA families in the ancestor of the V. viatica chromosomal races. Notably, 50 of these shared satDNA families underwent differential proliferation since the recent diversification of the V. viatica species complex. Conclusion This in-depth annotation of the repeatome in morabine grasshoppers provided new insights into the genome evolution of Orthoptera. Our TEs analysis revealed a massive recent accumulation of TEs equivalent to the size of entire Drosophila genomes, which likely explains the large genome sizes in grasshoppers. Despite an overall high similarity of the TE and satDNA diversity between races, the patterns of TE expression and satDNA proliferation suggest rapid evolution of grasshopper genomes on recent timescales.

Great Abundance of Satellite DNA in Proceratophrys (Anura, Odontophrynidae) Revealed by Genome Sequencing

2020 ◽  
Vol 160 (3) ◽  
pp. 141-147 ◽  
Author(s):  
Marcelo J. da Silva ◽  
Raquel Fogarin Destro ◽  
Thiago Gazoni ◽  
Hideki Narimatsu ◽  
Paulo S. Pereira dos Santos ◽  
...  
Keyword(s):  
Repetitive Dna ◽  
Sex Chromosomes ◽  
Dna Sequences ◽  
Satellite Dna ◽  
Sex Chromosome ◽  
Repetitive Sequences ◽  
Centromere Function ◽  
Sex Chromosome System ◽  
First Time ◽  
Eukaryotic Genomes

Most eukaryotic genomes contain substantial portions of repetitive DNA sequences. These are located primarily in highly compacted heterochromatin and, in many cases, are one of the most abundant components of the sex chromosomes. In this sense, the anuran Proceratophrys boiei represents an interesting model for analyses on repetitive sequences by means of cytogenetic techniques, since it has a karyotype with large blocks of heterochromatin and a ZZ/ZW sex chromosome system. The present study describes, for the first time, families of satellite DNA (satDNA) in the frog P. boiei. Its genome size was estimated at 1.6 Gb, of which 41% correspond to repetitive sequences, including satDNAs, rDNAs, transposable elements, and other elements characterized as non-repetitive. The satDNAs were mapped by FISH in the centromeric and pericentromeric regions of all chromosomes, suggesting a possible involvement of these sequences in centromere function. SatDNAs are also present in the W sex chromosome, occupying the entire heterochromatic area, indicating a probable contribution of this class of repetitive DNA to the differentiation of the sex chromosomes in this species. This study is a valuable contribution to the existing knowledge on repetitive sequences in amphibians. We show the presence of repetitive DNAs, especially satDNAs, in the genome of P. boiei that might be of relevance in genome organization and regulation, setting the stage for a deeper functional genome analysis of Proceratophrys.

A subtelomeric satellite DNA family isolated from the genome of the dioecious plant Silene latifolia

Genome ◽  
1999 ◽  
Vol 42 (3) ◽  
pp. 442-446 ◽  
Author(s):  
M A Garrido-Ramos ◽  
R de la Herrán ◽  
M Ruiz Rejón ◽  
C Ruiz Rejón
Keyword(s):  
Sex Chromosomes ◽  
Dna Sequences ◽  
Satellite Dna ◽  
Consensus Sequence ◽  
Repetitive Sequences ◽  
Restriction Enzymes ◽  
Repeat Sequence ◽  
Silene Latifolia ◽  
Telomere Repeat ◽  
Significant Length

In an ongoing effort to trace the evolution of the sex chromosomes of Silene latifolia, we have searched for the existence of repetitive sequences specific to these chromosomes in the genome of this species by direct isolation from low-melting agarose gels of satellite DNA bands generated by digestion with restriction enzymes. Five monomeric units belonging to a highly repetitive family isolated from Silene latifolia, the SacI family, have been cloned and characterized. The consensus sequence of the repetitive units is 313 bp in length (however, high variability exists for monomer length variants) and 52.9% in AT. Repeating units are tandemly arranged at the subtelomeric regions of the chromosomes in this species. The sequence does not possess direct or inverted sequences of significant length, but short direct repeats are scattered throughout the monomer sequence. Several short sequence motives resemble degenerate monomers of the telomere repeat sequence of plants (TTTAGGG), confirming a tight association between this subtelomeric satellite DNA and the telomere repeats. Our approach in this work confirms that SacI satellite DNA sequences are among the most abundant in the genome of S. latifolia and, on the other hand, that satellite DNA sequences specific of sex chromosomes are absent in this species. This agrees with a sex determination system less cytogenetically diverged from a bisexual state than the system present in other plant species, such as R. acetosa, or at least a lesser degree of differentiation between the sex chromosomes of S. latifolia and the autosomes.Key words: satellite DNA, sex chromosomes, Silene latifolia, subtelomeric sequences.

A moderately repetitive DNA sequence in alfalfa is transcribed in a floral-specific manner

Genome ◽  
1996 ◽  
Vol 39 (1) ◽  
pp. 9-16
Author(s):  
X. Xia ◽  
S. Du ◽  
L. Erickson
Keyword(s):  
Medicago Sativa ◽  
Dna Sequence ◽  
Repetitive Dna ◽  
Sequence Divergence ◽  
Coding Region ◽  
Flower Bud ◽  
Reading Frame ◽  
Sequence Homologies ◽  
Single Base Pair ◽  
Late Stages

Based on DNA sequence analysis of 5 clones of repetitive DNA from alfalfa (Medicago sativa), we propose the existence of a dispersed middle repetitive element about 3400 bp long with a copy number in the range of 2–3 × 103 per haploid genome. The average A + T content of the sequences was 54.6%, compared with 61.4% for the alfalfa genome. Sequence homologies between overlapping regions of the clones ranged from 85 to 89.5% with an average of 86.6%; sequence divergence was due largely to single base pair changes, with deletions or insertions occurring randomly across sequences. An open reading frame (ORF) in one clone, RPE15, contained homologies to cereal prolamin genes and a legumin box was located upstream of the coding region. A Northern blot of RNA from various alfalfa tissues, probed with the above clone containing this ORF, showed an extensive heterodispersed pattern of hybridization in the late stages of flower bud development but in no other tissues. Key words : lucerne, Medicago sativa, repetitive DNA, plant genomes.

scholarly journals Specific association of repetitive DNA sequences with major histocompatibility genes.

1983 ◽  
Vol 3 (5) ◽  
pp. 903-913 ◽  
Author(s):  
D S Singer ◽  
R Lifshitz ◽  
L Abelson ◽  
P Nyirjesy ◽  
S Rudikoff
Keyword(s):  
Dna Sequence ◽  
Repetitive Dna ◽  
Dna Sequences ◽  
Genomic Organization ◽  
Repetitive Dna Sequences ◽  
Major Histocompatibility ◽  
Sequence Organization ◽  
Sequence Elements ◽  
Mhc Locus ◽  
Specific Association

The DNA sequence organization of a 17.8-kilobase segment of porcine DNA, containing a functional major histocompatibility (MHC) gene, has been studied. The DNA flanking the MHC gene contains at least 10 distinct repetitive DNA sequence elements, each of which occurs only once within the 17.8-kilobase DNA segment. Their reiteration frequencies in the genome range from 10(2) to 10(4). The genomic organization of seven of these sequence elements has been examined; all are interspersed with other, unrelated DNA sequences. These seven repeated sequences are not generally associated in the genome. However, they appear to be nonrandomly linked in MHC-associated regions of the genome: at least two additional DNA segments containing MHC-homologous DNA also contain sequences homologous to DNA fragments bearing the seven different repeats. Of the seven sequences, four can be detected in splenic total RNA. These results suggest that these repeated elements are specifically associated with the MHC locus.

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