SEARCH · PubMed Health

Results for “DNA, Intergenic”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources

PubMed1990

Primate evolution at the DNA level and a classification of hominoids.

The genetic distances among primate lineages estimated from orthologous noncoding nucleotide sequences of beta-type globin loci and their flanking and intergenic DNA agree closely with the distances (delta T50H values) estimated by cross hybridization of total genomic single-copy DNAs. These DNA distances and the maximum parsimony tree constructed for the nucleotide sequence orthologues depict a branching pattern of primate lineages that is essentially congruent with the picture from phylogenetic analyses of morphological characters. The molecular evidence, however, resolves ambiguities in the morphological picture and provides an objective view of the cladistic position of humans among the primates. The molecular data group humans with chimpanzees in subtribe Hominina, with gorillas in tribe Hominini, orangutans in subfamily Homininae, gibbons in family Hominidae, Old World monkeys in infraorder Catarrhini, New World monkeys in semisuborder Anthropoidea, tarsiers in suborder Haplorhini, and strepsirhines (lemuriforms and lorisiforms) in order Primates. A seeming incongruency between organismal and molecular levels of evolution, namely that morphological evolution appears to have speeded up in higher primates, especially in the lineage to humans, while molecular evolution has slowed down, may have the trivial explanation that relatively small genetic changes may sometimes result in marked phenotypic changes.

Animals↗

PubMed2006

A simple and reliable method for DNA extraction from bivalve mantle.

A simple and reliable method was developed for extracting genomic DNA from preserved mantle tissues of Pacific oyster Crassostrea gigas for reproducible PCR amplification. The method was based on destruction of the tissue using Proteinase K, Chelex 100 resin, detergents, and urea, followed by preferential capturing of genomic DNA with silica particles. Approximately 5 mg of mantle tissue provided a sufficient quality and quantity of DNA for several hundreds of PCR reactions amplifying the hypervariable mitochondrial DNA intergenic spacer, which is a useful genetic marker for population structure analysis of Pacific oyster. The method can be applied for DNA preparation from not only fresh and frozen but also ethanol-preserved mantle tissues, so this rapid and economical method can serve for investigating a large number of bivalve specimens collected in the field and next transported in ethanol at ambient temperature.

Animals↗

PubMed2001

Identifying the 3'-terminal exon in human DNA.

MOTIVATION: We present JTEF, a new program for finding 3' terminal exons in human DNA sequences. This program is based on quadratic discriminant analysis, a standard non-linear statistical pattern recognition method. The quadratic discriminant functions used for building the algorithm were trained on a set of 3' terminal exons of type 3tuexon (those containing the true STOP codon). RESULTS: We showed that the average predictive accuracy of JTEF is higher than the presently available best programs (GenScan and Genemark.hmm) based on a test set of 65 human DNA sequences with 121 genes. In particular JTEF performs well on larger genomic contigs containing multiple genes and significant amounts of intergenic DNA. It will become a valuable tool for genome annotation and gene functional studies. AVAILABILITY: JTEF is available free for academic users on request from ftp://cshl.org/pub/science/mzhanglab/JTEF and will be made available through the World Wide Web (http://argon.cshl.org/).

Algorithms↗

PubMed2005

Phylogenetic analysis of encapsulated and non-encapsulated Trichinella species by studying the 5S rDNA tandemly repeated intergenic region.

The identification of sequence regions in the genomes of pathogens which can be useful to distinguish among species and genotypes, is of great importance for epidemiological, molecular, and phylogenetic studies. The 5S ribosomal DNA intergenic spacer region has been identified as a good target to distinguish among eight Trichinella species and genotypes. The recent discovery of two non-encapsulated species in this genus, Trichinella papuae and Trichinella zimbabwensis, which can infect both mammals and reptiles, has suggested analyzing their 5S rDNA. Amplification of the tandem repeats of the 5S rDNA intergenic region of encapsulated species of Trichinella shows a 751bp fragment, whereas the three non-encapsulated species show a fragment of 800bp with T. pseudospiralis showing an additional fragment of 522bp. Although the size of the 800bp PCR fragments of T. papuae and T. zimbabwensis are similar to that of T. pseudospiralis, there are differences in the 5S rDNA intergenic regions among the three non-encapsulated species. Phylogenetic analysis of the 5S rDNA intergenic regions shows a clustering together of the three non-encapsulated Trichinella species that is well separated from the encapsulated ones. In addition, a single PCR-based method allows distinguishing non-encapsulated and encapsulated species.

Animals↗

PubMed1997

A 370-kb cosmid contig of the serpin gene cluster on human chromosome 14q32.1: molecular linkage of the genes encoding alpha 1-antichymotrypsin, protein C inhibitor, kallistatin, alpha 1-antitrypsin, and corticosteroid-binding globulin.

The human genes encoding alpha 1-antitrypsin (alpha 1AT, gene symbol PI), corticosteroid-binding globulin (CBG), alpha 1-antichymotrypsin (AACT), and protein C inhibitor (PCI) are related by descent, and they all map to human chromosome 14q32.1. This serine protease inhibitor (serpin) gene cluster also contains an antitrypsin-related sequence (ATR, gene symbol PIL), but the precise molecular organization of this region has not been defined. In this report we describe the generation and characterization of an approximately 370-kb cosmid contig that includes all five serpin genes. Moreover, a newly described serpin, kallistatin (KAL, gene symbol PI4), was also mapped within the region. Gene order within this interval is cen-CBG-ATR-alpha 1 AT-KAL-PCI-AACT-tel. The genes occupy approximately 320 kb of genomic DNA, and they are organized into two discrete subclusters of three genes each that are separated by approximately 170 kb. The distal subcluster includes KAL, PCI, and AACT; it occupies approximately 63 kb of DNA, and all three genes are transcribed in a proximal-to-distal orientation. Within the subcluster, there is approximately 12 kb of intergenic DNA between KAL and PCI and approximately 19 kb between PCI and AACT. The proximal subcluster includes alpha 1AT, ATR, and CBG; it occupies approximately 90 kb of genomic DNA, with approximately 12 kb of DNA between alpha 1AT and ATR and approximately 40 kb between ATR and CBG. These genes are all transcribed in a distal-to-proximal orientation. This represents the first detailed physical map of the serpin gene cluster on 14q32.1.

Carrier Proteins↗

PubMed1994

A mammalian origin of bidirectional DNA replication within the Chinese hamster RPS14 locus.

Two complementary experimental approaches have been used to identify a chromosomal origin of bidirectional DNA replication within or immediately downstream of the Chinese hamster ribosomal protein S14 gene (RPS14). The replication origin, designated oriS14, maps within a 1.6- to 2.0-kbp region of RPS14 that includes the gene's third and fourth introns, exons IV plus V, and approximately 500 bp of proximal downstream flanking DNA. The nucleic acid sequence encoding oriS14 closely resembles the other mammalian chromosomal replication origins whose primary structures are known. It contains DNA binding sites for a large number of transcription factors, replication proteins, and mammalian oncogenes as well as several dinucleotide repeat motifs, an AT-rich region, and a sequence that is likely to bend the DNA. In contrast to the other well-characterized mammalian replication origins, which are autosomal and therefore carried as two copies per somatic cell, oriS14 is encoded by single-copy DNA within a hemizygous segment of chromosome 2q in CHO-K1 cells. Also, other known mammalian replication origins are situated in nontranscribed, intergenic DNA, whereas the DNA sequence encoding oriS14 substantially overlaps the transcribed portion of a constitutively expressed housekeeping gene.

Animals↗

PubMed2004

The DNA element controlling expression of the varicella-zoster virus open reading frame 28 and 29 genes consists of two divergent unidirectional promoters which have a common USF site.

The mechanism of the divergent expression of the varicella-zoster virus (VZV) ORF 28 and ORF 29 genes from a common intergenic DNA element, the ORF 28/29 promoter, is of interest based on the observation that both genes are expressed during VZV lytic infection but only the ORF 29 gene is expressed in latently infected neurons. In the work presented here, expression driven by the ORF 28/29 intergenic region was examined. We found that the promoter activity towards the ORF 29 direction is more responsive to activation by the major viral transactivator IE62 than that towards the ORF 28 direction in the context of our experimental system. Analysis of the functional DNA elements involved in IE62 activation of the bidirectional ORF 28/29 regulatory element revealed that in both transfected and VZV-superinfected cells it is a fusion of two unidirectional promoters overlapping an essential USF binding site but with distinct TATA elements. A single TATA element directs expression in the ORF 28 direction, whereas the two TATA elements directing ORF 29 gene expression are alternatively and differentially utilized for transcription initiation. We also identified an Sp1 site localized proximal to the ORF 28 gene which functions as an activator element for expression in both directions. These results indicate that the ORF 28 and ORF 29 genes can be expressed either coordinately or independently and that the observed expression of only the ORF 29 gene during VZV latency may involve neuron-specific cellular factors and/or structural aspects of the latent viral genome.

Base Sequence↗

PubMed1984

Tandem arrangement of the albumin and alpha-fetoprotein genes in the human genome.

A genomic clone containing human albumin mRNA sequences was isolated from a lambda phage gene library derived from a human hepatoma cell line that produces alpha-fetoprotein (AFP) and albumin. This clone was also found to hybridize with the 5'-flanking region of the human AFP gene. Restriction mapping and nucleotide sequencing revealed that the albumin and AFP genes are present in tandem, in the same transcriptional orientation, with the albumin gene 14.5 kb upstream of the AFP gene. We have also isolated a genomic clone carrying both the albumin and AFP gene sequences from human fibroblasts, which produce neither AFP nor albumin. This DNA showed a restriction map that was indistinguishable from that of the clone obtained from the hepatoma described above, demonstrating that no gross rearrangements of the intergenic DNA sequence are involved in control of expression of the AFP and albumin genes.

Bacteriophage lambda↗

PubMed1998

Structure and function of proteins controlling strain-specific pathogen resistance in plants.

Recently recognised structural and amino acid sequence similarities between plant disease resistance (R) proteins and animal proteins such as Apaf-1 and CED-4 are providing conceptual models for resistance protein function. Data from extensive DNA sequencing of resistance gene families are indicating that the leucine-rich repeat motif is an important determinant of gene-for-gene specificity and that intergenic DNA sequence exchange is a major contributor to R gene diversity.

Apoptosis↗

PubMed1997

Bacterial interspersed mosaic elements (BIMEs) are a major source of sequence polymorphism in Escherichia coli intergenic regions including specific associations with a new insertion sequence.

A significant fraction of Escherichia coli intergenic DNA sequences is composed of two families of repeated bacterial interspersed mosaic elements (BIME-1 and BIME-2). In this study, we determined the sequence organization of six intergenic regions in 51 E. coli and Shigella natural isolates. Each region contains a BIME in E. coli K-12. We found that multiple sequence variations are located within or near these BIMEs in the different bacteria. Events included excisions of a whole BIME-1, expansion/deletion within a BIME-2 and insertions of non-BIME sequences like the boxC repeat or a new IS element, named IS 1397. Remarkably, 14 out of IS 1397 integration sites correspond to a BIME sequence, strongly suggesting that this IS element is specifically associated with BIMEs, and thus inserts only in extragenic regions. Unlike BIMEs, IS 1397 is not detected in all E. coli isolates. Possible relationships between the presence of this IS element and the evolution of BIMEs are discussed.

Amino Acid Sequence↗

PubMed1989

Extrachromosomal circular DNAs in Drosophila melanogaster: comparison between embryos and Kc0% cells.

We established the size distribution of extrachromosomal covalently closed circular DNA molecules from embryos of various Drosophila melanogaster strains and from Kc0% tissue culture cells. In embryos, more than 80% of the circular DNA molecules are smaller than 2.5 kb and all the distributions show a peak of molecules of between 200 and 400 bp. The Kc0% cell distribution differs mainly from that of embryos in that 48% of the molecules have a size between 4 and 8 kb. Correlating with this, circular molecules homologous to copia, 412 and 297 were detected only in Kc0% cells. The three tandemly repeated families containing the 5S genes, the histone genes and the 240 bp repeat of the ribosomal DNA intergenic spacer, which had previously been identified in circular DNAs from embryos, were also found in cultured cells. A fourth tandemly repeated family corresponding to the 1.688 g/cm3 satellite DNA was detected, both in embryos and Kc0% cells. It consists of circular multimeric molecules containing multiple copies of the 359 bp repeated unit. No circular DNA molecules homologous to the actin genes, the type I ribosomal DNA insertion, or the F and I transposable elements were found in embryos or Kc0% cells. Thus it appears that the extrachromosomal circular DNA molecules from embryos and from tissue culture cells differ mainly in the presence of circular copies of the copia-like transposable elements.

Animals↗

PubMed1984

Polyomavirus and simian virus 40 large T antigens bind to common DNA sequences.

The large T antigens of polyomavirus and simian virus 40 (SV40) recognize and bind to specific, noncoding DNA sequences which are located between the beginning of the early and late transcription units in their respective genomes. Each large T antigen binds to multiple sites within this intergenic DNA stretch. Polyomavirus large T antigen binds to at least two sites within its DNA, and SV40 large T antigen binds to three sites within SV40 DNA. Comparison of the DNA sequences which comprise the binding sites in polyomavirus DNA or those which make up the binding sites in SV40 DNA has led to recognition of a common sequence, -GAGGC-, which is repeated within each large-T-antigen-binding site. We tested the hypothesis that repeats of this pentanucleotide form the recognition-binding site for polyomavirus and SV40 large T antigen. This was accomplished by measuring the binding of each large T antigen to both polyomavirus and SV40 DNA and to synthetic DNA substrates which did or did not contain repeats of the -GAGGC- sequence. Polyomavirus large T antigen bound to specific fragments of SV40 DNA, and SV40 large T antigen bound with specificity to polyomavirus DNA. In each case, the DNA fragments bound by the heterologous large T antigen were the same as those bound by the homologous large T antigen. Moreover, polyomavirus and SV40 large T antigen only bound to synthetic DNA substrates which contained repeats of the pentameric sequence. This synthetic DNA also competed effectively with native polyomavirus or SV40 DNA as a substrate in binding reactions with one or the other large T antigen. These results led us to conclude that repeats of the -GAGGC- sequence form the recognition-binding site for both polyomavirus and SV40 large T antigen.

Animals↗

PubMed1995

Transition in specification of embryonic metazoan DNA replication origins.

In early Xenopus embryos, in which ribosomal RNA genes (rDNA) are not transcribed, rDNA replication initiates and terminates at 9- to 12-kilobase pair intervals, with no detectable dependence on specific DNA sequences. Resumption of ribosomal RNA (rRNA) synthesis at late blastula and early gastrula is accompanied by a specific repression of replication initiation within transcription units; the frequency of initiation within intergenic spacers remains as high as in early blastula. These results demonstrate that for rRNA genes, circumscribed zones of replication initiation emerge in intergenic DNA during the time in metazoan development when the chromatin is remodeled to allow gene transcription.

Animals↗

PubMed2005

Plant-derived transfer DNAs.

The transfer of DNA from Agrobacterium to plant cell nuclei is initiated by a cleavage reaction within the 25-bp right border of Ti plasmids. In an effort to develop all-native DNA transformation vectors, 50 putative right border alternatives were identified in both plant expressed sequence tags and genomic DNA. Efficacy tests in a tobacco (Nicotiana tabacum) model system demonstrated that 14 of these elements displayed at least 50% of the activity of conventional Agrobacterium transfer DNA borders. Four of the most effective plant-derived right border alternatives were found to be associated with intron-exon junctions. Additional elements were embedded within introns, exons, untranslated trailers, and intergenic DNA. Based on the identification of a single right border alternative in Arabidopsis and three in rice (Oryza sativa), the occurrence of this motif was estimated at a frequency of at least 0.8x10(-8). Modification of plasmid DNA sequences flanking the alternative borders demonstrated that both upstream and downstream sequences play an important role in initiating DNA transfer. Optimal DNA transfer required the elements to be preceded by pyrimidine residues interspaced by AC-rich trinucleotides. Alteration of this organization lowered transformation frequencies by 46% to 93%. Despite their weaker resemblance with left borders, right border alternatives also functioned effectively in terminating DNA transfer, if both associated with an upstream A[C/T]T[C/G]A[A/T]T[G/T][C/T][G/T][C/G]A[C/T][C/T][A/T] domain and tightly linked cytosine clusters at their junctions with downstream DNA. New insights in border region requirements were used to construct an all-native alfalfa (Medicago sativa) transfer DNA vector that can be used for the production of intragenic plants.

Amino Acid Sequence↗

PubMed2006

Involvement of DNA curvature in intergenic regions of prokaryotes.

It is known that DNA curvature plays a certain role in gene regulation. The distribution of curved DNA in promoter regions is evolutionarily preserved, and it is mainly determined by temperature of habitat. However, very little is known on the distribution of DNA curvature in termination sites. Our main objective was to comprehensively analyze distribution of curved sequences upstream and downstream to the coding genes in prokaryotic genomes. We applied CURVATURE software to 170 complete prokaryotic genomes in a search for possible typical distribution of DNA curvature around starts and ends of genes. Performing cluster analyses and other statistical tests, we obtained novel results regarding various factors influencing curvature distribution in intergenic regions, such as growth temperature, A+T composition and genome size. We also analyzed intergenic regions between converging genes in 15 selected genomes. The results show that six genomes presented peaks of curvature excess larger than 3 SDs. Insufficient statistics did not allow us to draw further conclusion. Our hypothesis is that DNA curvature could affect transcription termination in many prokaryotes either directly, through contacts with RNA polymerase, or indirectly, via contacts with some regulatory proteins.

Cluster Analysis↗

PubMed1989

Conjugative transfer of promiscuous IncP plasmids: interaction of plasmid-encoded products with the transfer origin.

To characterize protein-DNA interactions involved in the initiation of conjugative transfer replication, we isolated and sequenced the transfer origins (oriT) of the promiscuous IncP plasmids RP4 and R751. The central initiating event at the transfer origin of a conjugative plasmid is the cleavage at a unique site (nic) of the strand to be transferred to a recipient cell. This process can be triggered after the assembly of "relaxosomes" (plasmid DNA-protein relaxation complexes), requiring plasmid-encoded gene products. We analyzed the nicking reaction for plasmid RP4 and demonstrated that one of the plasmid strands is specifically cleaved within oriT. The fully functional oriT of RP4 represents an intergenic DNA region of approximately 350 base pairs. Dissection of oriT revealed that a portion carrying nic and symmetric sequence repeats determines oriT specificity. This part of oriT is contiguous to a region that is essential for efficient mobilization of oriT plasmids. In addition, oriT contains potential promoter sites allowing divergent transcription of two operons flanking oriT. We over-produced gene products and, from analyzing the products of defined deletion mutants, deduced the gene arrangements. Formation of RP4 relaxosomes is likely to depend on the presence of at least two plasmid-encoded components, which act in trans. Corresponding genes map on one side of oriT. Purification of the traJ product revealed it to be an 11-kDa polypeptide that binds to oriT DNA in vitro. The protein recognizes the part of oriT that is responsible for oriT specificity.

Base Sequence↗

PubMed1987

Molecular evolution of the Saccharomyces cerevisiae histone gene loci.

The core histone genes of Saccharomyces cerevisiae are arranged as duplicate nonallelic sets of specifically paired genes. The identity of structural organization between the duplicated gene pairs would have its simplest evolutionary origin in the duplication of a complete locus in a single event. In such a case, the time since the duplication of one of the genes should be identical to that since duplication of the gene adjacent to it on the chromosome. A calculation of the evolutionary distances between the coding DNA sequences of the histone genes leads to a duplication paradox: The extents of sequence divergence in the silent component of third-base positions for adjacent pairs of genes are not identical. Estimates of the evolutionary distance between the two H3-H4 noncoding intergene DNA sequences are large; the divergence between the two separate sequences is indistinguishable from the divergence between either of the regions and a randomly generated permutation of itself. These results suggest that the duplication event may have occurred much earlier than previously estimated. The potential age of the duplication, and the attractive simplicity of the duplication of both the H3-H4 and the H2A-H2B gene pairs having taken place in a single event, leads to the hypothesis that modern haploid S. cerevisiae may have evolved by diploidization or fusion of two ancient fungi.

Base Sequence↗

PubMed2001

Pseudogenes, junk DNA, and the dynamics of Rickettsia genomes.

Studies of neutrally evolving sequences suggest that differences in eukaryotic genome sizes result from different rates of DNA loss. However, very few pseudogenes have been identified in microbial species, and the processes whereby genes and genomes deteriorate in bacteria remain largely unresolved. The typhus-causing agent, Rickettsia prowazekii, is exceptional in that as much as 24% of its 1.1-Mb genome consists of noncoding DNA and pseudogenes. To test the hypothesis that the noncoding DNA in the R. prowazekii genome represents degraded remnants of ancestral genes, we systematically examined all of the identified pseudogenes and their flanking sequences in three additional Rickettsia species. Consistent with the hypothesis, we observe sequence similarities between genes and pseudogenes in one species and intergenic DNA in another species. We show that the frequencies and average sizes of deletions are larger than insertions in neutrally evolving pseudogene sequences. Our results suggest that inactivated genetic material in the Rickettsia genomes deteriorates spontaneously due to a mutation bias for deletions and that the noncoding sequences represent DNA in the final stages of this degenerative process.

Base Sequence↗