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PubMed2025

Molecular epidemiological surveillance for non-tuberculous mycobacterial pulmonary disease: a single-center prospective cohort study.

UNLABELLED: Bacterial species cultured from sputum change during treatment or observation for non-tuberculous mycobacterial pulmonary disease; however, strain-level changes remain unrecognized. Variable number tandem repeat typing is a standard technique for strain identification; nonetheless, its labor-intensive and time-consuming nature limits routine clinical use. Therefore, we aimed to elucidate species-subspecies and strain dynamics in non-tuberculous mycobacteria and develop a simple sequence-based strain-level determination method. We performed a single-center prospective cohort study of 112 patients with non-tuberculous mycobacterial pulmonary disease. Whole-genome sequencing was performed on two sputum samples collected at enrollment and at the end of follow-up, followed by variable number tandem repeat (VNTR) typing. We also developed a simple long-read sequencing-based digital VNTR (dVNTR) typing method and evaluated its efficacy. Our results demonstrate that core genome multi-locus sequencing typing revealed species/subspecies changes in 13 patients (11.6%); VNTR typing detected strain changes in 16 patients (14.3%) without species/subspecies changes. Overall, pathogen shifts occurred in 29 patients (shift [+] group, 25.9%), whereas 83 had no detectable pathogen shift (shift [-] group, 74.1%). Interestingly, macrolide and amikacin susceptibility changed in both groups, but resistance remained higher in shift (-) patients. dVNTR results aligned with those of conventional VNTR typing. In conclusion, since susceptibility factors remain unclear, routine species/subspecies identification and molecular typing, such as VNTR, are optimal for patient care. Core genome multi-locus sequencing typing with a dVNTR identified pathogen shifts, innovating non-tuberculous mycobacterial pulmonary disease management.Clinical TrialsThis study is registered with UMIN as UMIN 000056067. IMPORTANCE: Pulmonary non-tuberculous mycobacterial disease is a chronic infection in which the causative pathogens may change at the species, subspecies, or strain level over time. Accurate tracking of these changes is essential for optimizing treatment; however, conventional clinical practice lacks efficient methods for monitoring such dynamics. Our study revealed pathogen changes in approximately one-quarter of patients over 1.5 years, prompting the development of a novel surveillance system that integrates next-generation sequencing for both species-subspecies identification and strain-level molecular epidemiology. This innovation enables real-time monitoring of pathogen dynamics, allowing clinicians to promptly adjust treatment strategies and improve patient care through more informed decision-making.

Humans↗

PubMedDate not supplied

[Features of the structure and evolution of complex, tandemly organized Bsp-repeats in the fox genome. I. Structure and internal organization of the BamHI-dimer].

A 1468 b.p. DNA BamHI-fragment homologous to the Bsp-repeat was isolated from the fox genome and sequenced. This fragment is an hierarchically arranged dimer. Its 734 b.p.-monomers consist of three subrepeats (SR), each 245 b.p. long, abundant with overlapping imperfect tandem repeats which in turn are rich in short direct related repeats (each 4-7 b.p. in size). The latters are mainly composed of AG, TG dinucleotides and their complements CT, CA. All subrepeats in the BamHI-dimer are flanked by motifs homologous to Jeffreys' sites. At certain points the sites are doubled. The above data allow to assume that the Bsp-repeat complex structure is likely to have developed throughout long multi-step evolution of relatively simple DNA sequences which had emerged de novo. Single substitutions, small inserts and deletions, multiple duplication and recombination events seem to have most contributed to the evolution of the Bsp-repeats. Single substitutions in SRs with respect to the consensus are not equally distributed along their length. A wave-like pattern of this distribution is the evidence for non-random character of mutations accumulation. A correspondence was noted between conservative regions in SR and the presence therein of functional motifs homologous to the binding sites of already known regulatory proteins.

Animals↗

PubMed1988

Molecular evolution of intergenic DNA in higher primates: pattern of DNA changes, molecular clock, and evolution of repetitive sequences.

A 3.1-kb intergenic DNA fragment located between the psi beta-globin and delta-globin genes in the beta-globin gene cluster was cloned from gorilla, orangutan, rhesus monkey, and spider monkey, and the nucleotide sequence of each fragment was determined. The phylogeny of these four sequences, together with two previously published allelic sequences from humans and one from chimpanzee, was constructed, and the accumulation of mutations in the region was analyzed. The sites of base substitutions are not evenly distributed within the region: two Alu repeats have accumulated 0.21 + 0.02 substitutions/site with 0.15 + 0.008 substitutions/site in the remainder of the fragment. The occurrence of substitutions at neighboring sites is more frequent than would be expected if they were independent. The observed excesses disappear when ancestral -CG- dinucleotide sites are excluded. The phylogenetic relationships of the sequences indicate that the human sequence shares a most recent coancestor with the chimpanzee sequence. The data also show that great apes have accumulated fewer mutations in this part of the genome than has the rhesus monkey. The relative rates of accumulation of 12 kinds of nucleotide substitution in the region during primate evolution are asymmetric in the DNA strands. From these rates of accumulation, the origin of a simple stretch of sequence near the 3' end of the 3.1-kb fragment was deduced to be a sequence comprising 50% T and 50% C on one strand. The two oppositely oriented Alu sequences in the 3.1-kb region were inserted at their present positions before the divergence of the New-World monkeys from other lineages. Our analysis shows that the nucleotide sequences of the two Alu repeats in spider monkey are unexpectedly similar both to each other and to the deduced ancestral sequence of Alu repeats. The data suggest that there has been some type of recombinational event between the spider monkey Alu repeats but that it was not a simple gene conversion.

Animals↗

PubMed1987

Rapid identification of hybridization probes for chromosomal walking.

The presence of repeated elements in restriction fragments used as hybridization probes for chromosomal walking poses a major obstacle to the success of this gene-cloning strategy. This report describes a simple and rapid means of identifying restriction fragments devoid of repeated sequences and therefore useful as hybridization probes for chromosomal walking. Restriction fragments derived from a genomic DNA clone are Southern blotted and hybridized to nick-translated total genomic [32P]DNA. Fragments of the genomic clone that contain high abundance sequences (i.e., repeated elements) hybridize strongly to their nick-translated counterparts, which, due to their high copy number, comprise a significant proportion of the total genomic DNA probe. Conversely, fragments containing single-copy or low-abundance sequences do not hybridize, as their nick-translated counterparts are poorly represented in the total genomic DNA probe. These latter fragments, by virtue of their low-abundance sequences, are well suited as probes for chromosomal walking. Ensuring the absence of repeated elements in restriction fragments prior to their purification and utilization as chromosomal walking probes results in marked savings of time, effort and materials.

Bacteriophage lambda↗

PubMedDate not supplied

Unusual sequences in the murine immunoglobulin mu-delta heavy-chain region.

The delta heavy (H) chain of mouse immunoglobulin D (IgD) is unusual both in its structure and in its differential expression relative to immunoglobulin M (IgM; reviewed in ref. 1). The region of DNA between IgM and IgD H-chain constant-region genes is probably implicated in this control. So far only fragments of the area have been sequenced. Now, however, we present the complete sequence as well as the sequence of the introns of the C delta gene. We have found several interesting features (Fig. 1), including an open reading frame (ORF) between Cmu and C delta which encodes 146 amino acids that might represent a previously unsuspected domain-like protein; three blocks of simple repetitive sequences; a 162-base pair (bp) unique-sequence inverted repeat; and a domain-like pseudogene in the large intron of C delta. We have not found, however, any sequence 5' of C delta resembling the switch (S) recombination sequences associated with class switching in other heavy chains. Moreover, we have determined the 3' deletion end point of an IgD-producing myeloma and find no sequences reminiscent of switch sites nearby.

Animals↗

PubMed1989

Amplification of the ribonucleotide reductase small subunit gene: analysis of novel joints and the mechanism of gene duplication in vaccinia virus.

Amplification of the M2 gene encoding the small subunit of ribonucleotide reductase (EC 1.17.4.1) was analyzed in a collection of vaccinia virus (VV) isolates selected for resistance to 5 mM hydroxyurea (HU). Most of the mutants harbored tandem direct repeat arrays of the M2 gene, but several had duplicated M2 as an inverted repeat by genomic rearrangements involving the chromosomal termini. Novel joints formed by direct repeats were mapped, amplified in vitro, and sequenced. The junctions were simple fusions between DNA downstream and upstream of the M2 gene. Lack of sequence homology at the breakpoints indicated that the initial genomic rearrangements leading to gene amplification were due to nonhomologous recombination events.

Base Sequence↗

PubMed1990

Duplicative activation mechanisms of two trypanosome telomeric VSG genes with structurally simple 5' flanks.

In the mammalian bloodstream, African trypanosomes express variant surface glycoprotein (VSG) genes from a family of long and complex telomeric expression sites. VSG switching generally occurs by the duplication of different VSG genes into these sites by gene conversion involving a series of 70 base pair (70bp) repeats in the 5' flank. In contrast, when VSG is first synthesised by trypanosomes in the tsetse fly at the metacyclic stage, a separate set of telomeric expression sites is activated. These latter telomeres appear not to act as recipients in gene conversion. We have found that the structure of two such expression sites is simple, with very short 70bp repeat regions and very little other sequence in common with bloodstream expression sites. However, the two telomeres readily act as donors in VSG gene conversion in the bloodstream and we show for one a consistent association of the conversion 5' end point with the short 70bp repeat region. These findings help explain why a very predictable set of VSGs is expressed in the tsetse fly and have implications for VSG gene conversion mechanisms.

Animals↗

PubMed1986

An excision event that may depend on patchy homology for site specificity.

In mouse cells transformed by a mutant polyomavirus genome, recombination between integrated viral DNA and flanking cellular DNA resulted in the excision of two readily amplifiable chimeras, designated RmI and RmII. The crossing-over that generated RmII was unique in that it involved a simple cellular sequence in which the triplet 5'-CTG-3' was repeated many times. We show that the sequence across the junction resulting from excision was identical in several molecules of RmII, as if the cross-over generating this junction always involved exactly the same two sites on the viral and cellular DNA. We also show that the cellular site mapped where the replacement of a G by an A in one of many successive 5'-CTG-3' triplets generated a homology of five nucleotides (5'-CTACT-3') with the viral site. Oligonucleotides on both sides of these sites are probably involved in matching the two DNAs prior to recombination.

Animals↗

PubMed1993

In vitro amplification of hypervariable DNA regions for the evaluation of chimerism after allogeneic BMT.

The role of mixed hematopoietic chimerism in engraftment and relapse after allogeneic BMT remains unclear. To better evaluate post-transplant chimerism we used polymerase chain reaction (PCR) in vitro amplification of four single locus simple repetitive DNA sequences, all of which vary extensively in their repeat number among different individuals: variable number of tandem repeats D1S80, APOB and D17S5, and the tetranucleotide repeat F8VWF. We tested 13 cases of CML, four of multiple myeloma (MM), three of ANLL and one of B-CLL. In a sequential analysis protocol with the different loci, the donor could be distinguished from the recipient in 14 of 20 (70%) pairs with the first marker used (D1S80). When a donor of opposite sex was involved, karyotyping and Y chromosome-specific PCR were also used. With the use of the four markers, chimerism was identified in all the pairs. Mixed chimerism was present in 5 patients, and complete chimerism in 15. No patients relapsed. The application of PCR for documenting post-transplant chimerism has several advantages over Southern blotting: increased sensitivity, use of small amounts of sample, ease of preparation of DNA, elimination of restriction enzyme analysis and of radioisotopes, and speed.

Adult↗

PubMed2005

Identification and characterization of tandem repeats in exon III of dopamine receptor D4 (DRD4) genes from different mammalian species.

In this study we have identified and characterized dopamine receptor D4 (DRD4) exon III tandem repeats in 33 public available nucleotide sequences from different mammalian species. We found that the tandem repeat in canids could be described in a novel and simple way, namely, as a structure composed of 15- and 12- bp modules. Tandem repeats composed of 18-bp modules were found in sequences from the horse, zebra, onager, and donkey, Asiatic bear, polar bear, common raccoon, dolphin, harbor porpoise, and domestic cat. Several of these sequences have been analyzed previously without a tandem repeat being found. In the domestic cow and gray seal we identified tandem repeats composed of 36-bp modules, each consisting of two closely related 18-bp basic units. A tandem repeat consisting of 9-bp modules was identified in sequences from mink and ferret. In the European otter we detected an 18-bp tandem repeat, while a tandem repeat consisting of 27-bp modules was identified in a sequence from European badger. Both these tandem repeats were composed of 9-bp basic units, which were closely related with the 9-bp repeat modules identified in the mink and ferret. Tandem repeats could not be identified in sequences from rodents. All tandem repeats possessed a high GC content with a strong bias for C. On phylogenetic analysis of the tandem repeats evolutionary related species were clustered into the same groups. The degree of conservation of the tandem repeats varied significantly between species. The deduced amino acid sequences of most of the tandem repeats exhibited a high propensity for disorder. This was also the case with an amino acid sequence of the human DRD4 exon III tandem repeat, which was included in the study for comparative purposes. We identified proline-containing motifs for SH3 and WW domain binding proteins, potential phosphorylation sites, PDZ domain binding motifs, and FHA domain binding motifs in the amino acid sequences of the tandem repeats. The numbers of potential functional sites varied pronouncedly between species. Our observations provide a platform for future studies of the architecture and evolution of the DRD4 exon III tandem repeat, and they suggest that differences in the structure of this tandem repeat contribute to specialization and generation of diversity in receptor function.

Amino Acid Motifs↗

PubMed2003

Characterization of eight Y-STR loci and haplotypes in a Chinese Han population.

In this study we analyzed the eight Y-STR loci, DYS443, DYS444, DYS448, DYS453, DYS455, DYS456, DYS457 (DYS437) and DYS458, investigated haplotype distributions of these Y-STR loci in a Chinese Han population, and sequenced alleles of the eight loci for clarifying the structure. Extracted DNA was amplified by PCR and the PCR products were analyzed by non-denaturing horizontal polyacrylamide gel electrophoresis with a discontinuous buffer system. Alleles were sequenced on an ABI 3700 using a Dye Terminator Cycle sequencing kit. DYS443, DYS453, DYS455 and DYS456 were found to be simple repeat systems, while DYS444, DYS448, DYS457 (DYS437) and DYS458 were complex repeat systems. The gene diversities of DYS443, DYS444, DYS448, DYS453, DYS455, DYS456, DYS457 (DYS437) and DYS458 were 0.7742, 0.7671, 0.7453, 0.3545, 0.0549, 0.6988, 0.6148 and 0.8213, respectively. The haplotype diversity for 8 Y-STR loci was 0.9996, and the discrimination capacity was 0.9815. The results indicate that these eight loci are useful Y-linked markers for forensic applications.

Alleles↗

PubMed1990

Organization, structure, and polymorphisms of the human profilaggrin gene.

Profilaggrin is a major protein component of the keratohyalin granules of mammalian epidermis. It is initially expressed as a large polyprotein precursor and is subsequently proteolytically processed into individual functional filaggrin molecules. We have isolated genomic DNA and cDNA clones encoding the 5'- and 3'-ends of the human gene and mRNA. The data reveal the presence of likely "CAT" and "TATA" sequences, an intron in the 5'-untranslated region, and several potential regulatory sequences. While all repeats are of the same length (972 bp, 324 amino acids), sequences display considerable variation (10-15%) between repeats on the same clone and between different clones. Most variations are attributable to single-base changes, but many also involve changes in charge. Thus, human filaggrin consists of a heterogeneous population of molecules of different sizes, charges, and sequences. However, amino acid sequences encoding the amino and carboxyl termini are more conserved, as are the 5' and 3' DNA sequences flanking the coding portions of the gene. The presence of unique restriction enzyme sites in these conserved flanking sequences has enabled calculations on the size of the full-length gene and the numbers of repeats in it: depending on the source of genomic DNA, the gene contains 10, 11, or 12 filaggrin repeats that segregate in kindred families by normal Mendelian genetic mechanisms. This means that the human profilaggrin gene system is also polymorphic with respect to size due to simple allelic differences between different individuals. The amino- and carboxyl-terminal sequences of profilaggrin contain partial or truncated repeats with unusual un-filaggrin-like sequences on the termini.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗

PubMed1990

Simple human DNA-repeats associated with genomic hypervariability, flanking the genomic retroposons and similar to retroviral sites.

Earlier we found a human hypervariable genomic region (GVR). The DNA hybridization probe isolated from this region detects multiple hypervariability of restriction DNA fragments from genomic loci. The sequencing data suggest that the genomic instability and variability are associated with tandem DNA repeats. The DNA hybridization probe contains two families of simple DNA repeats designated as 'apo' and 'tau'. The (TC)n-rich family of DNA 'tau'-repeats bears some similarity to the simple transcribed repeats of Drosophila virilis, simple repetitive motifs of the human proenkephaline gene exon 1, and short sites of retroviral LTR ends. Apo-repeats show an unusual similarity to Rauscher viral env gene site. Besides GVR, apo- and tau-like repeats are localized in other genomic loci and can form separate tandem clusters and terminal repeats flanking certain copies of retroposons (Alu-SINES).

Base Sequence↗

PubMed1980

Highly repetitive component alpha and related alphoid DNAs in man and monkeys.

The genomes of Old-World, New-World, and prosimian primates contain members of a large class of highly repetitive DNAs that are related to one another and to component alpha DNA of the African green monkey by their sequence homologies and restriction site periodicities. The members of this class of highly repetitive DNAs are termed the alphoid DNAs, after the prototypical member, component alpha of the African green monkey which was the first such DNA to be identified (Maio, 1971) and sequenced (Rosenberg et al., 1978). The alphoid DNAs appear to be uniquely primate sequences.--From the restriction enzyme cleavage patterns and Southern blot hybridizations under different stringency conditions, the alphoid DNAs comprise multiple sequence families exhibiting varying degrees of homology to component alpha DNA. They also share common elements in their restriction site periodicities (172 . n base-pairs), in the long-range organization of their repeating units, and in their banding behavior in CsCl and Cs2SO4 bouyant density gradients, in which they band within the bulk DNA as cryptic repetitive components.--In the three species from the Family Cercopithecidae examined, the alphoid DNAs represent the most abundant, tandemly repetitive sequence components, comprising about 24% of the African green monkey genome and 8 to 10% of the Rhesus monkey and baboon genomes. In restriction digests, the bulk of the alphoid DNAs among the Cercopithecidae appeared quantitatively reduced to a simple series of arithmetic segments based on a 172 base-pair (bp) repeat. In contrast with these simple restriction patterns, complex patterns were observed when human alphoid DNAs were cleaved with restriction enzymes. Detailed analysis revealed that the human genome contains multiple alphoid sequence families which differ from one another both in their repeat sequence organization and in their degree of homology to the African green monkey component alpha DNA.--The finding of alphoid sequences in other Old-World primate families, in a New-World monkey, and in a prosimian primate attests to the antiquity of these sequences in primate evolution and to the sequence conservatism of a large class of mammalian highly repetitive DNA. In addition, the relative conservatism exhibited by these sequences may distinguish the alphoid DNAs from more recently evolved highly repetitive components and satellite DNAs which have a more restricted taxonomical distribution.

Animals↗

PubMed1995

ST-1, a 39-kilodalton protein in Trypanosoma brucei, exhibits a dual affinity for the duplex form of the 29-base-pair subtelomeric repeat and its C-rich strand.

In our attempt to identify telomere region-binding proteins in Trypanosoma brucei, we identified ST-1, a polypeptide with novel features. ST-1 was chromatographically purified from S-100 cell extracts and was renatured from a sodium dodecyl sulfate-protein gel as a 39-kDa polypeptide. It forms a specific complex with the trypanosome telomere repeats of TTAGGG, but more significantly, it shows a higher affinity for the 29-bp subtelomere repeats of T. brucei. These 29-mer boxes are a large tandem series of telomere-derived repeats which separate the simple telomere DNA from middle-repetitive telomere-associated sequences on many chromosomes. ST-1 is the first example of a protein binding within such large repetitive subtelomere elements in trypanosomes or other organisms. ST-1 is also novel in that it has a selective affinity for the C-rich strands of both the subtelomeric 29-mer and the telomere repeats, comparable to that for the duplex form of the respective repeats. All previously described telomere-binding proteins have affinity for only the duplex form or for the G-rich strand. This C-rich strand binding specificity of ST-1 may provide insight into this protein's mechanism of binding in vivo.

Animals↗

PubMed2001

A tandem repeats database for bacterial genomes: application to the genotyping of Yersinia pestis and Bacillus anthracis.

BACKGROUND: Some pathogenic bacteria are genetically very homogeneous, making strain discrimination difficult. In the last few years, tandem repeats have been increasingly recognized as markers of choice for genotyping a number of pathogens. The rapid evolution of these structures appears to contribute to the phenotypic flexibility of pathogens. The availability of whole-genome sequences has opened the way to the systematic evaluation of tandem repeats diversity and application to epidemiological studies. RESULTS: This report presents a database (http://minisatellites.u-psud.fr) of tandem repeats from publicly available bacterial genomes which facilitates the identification and selection of tandem repeats. We illustrate the use of this database by the characterization of minisatellites from two important human pathogens, Yersinia pestis and Bacillus anthracis. In order to avoid simple sequence contingency loci which may be of limited value as epidemiological markers, and to provide genotyping tools amenable to ordinary agarose gel electrophoresis, only tandem repeats with repeat units at least 9 bp long were evaluated. Yersinia pestis contains 64 such minisatellites in which the unit is repeated at least 7 times. An additional collection of 12 loci with at least 6 units, and a high internal conservation were also evaluated. Forty-nine are polymorphic among five Yersinia strains (twenty-five among three Y. pestis strains). Bacillus anthracis contains 30 comparable structures in which the unit is repeated at least 10 times. Half of these tandem repeats show polymorphism among the strains tested. CONCLUSIONS: Analysis of the currently available bacterial genome sequences classifies Bacillus anthracis and Yersinia pestis as having an average (approximately 30 per Mb) density of tandem repeat arrays longer than 100 bp when compared to the other bacterial genomes analysed to date. In both cases, testing a fraction of these sequences for polymorphism was sufficient to quickly develop a set of more than fifteen informative markers, some of which show a very high degree of polymorphism. In one instance, the polymorphism information content index reaches 0.82 with allele length covering a wide size range (600-1950 bp), and nine alleles resolved in the small number of independent Bacillus anthracis strains typed here.

Bacillus anthracis↗

PubMed2000

Replicability and recurrence in the experimental evolution of a group I ribozyme.

In order to explore the variety of possible responses available to a ribozyme population evolving a novel phenotype, five Tetrahymena thermophila group I intron ribozyme pools were evolved in parallel for cleavage of a DNA oligonucleotide. These ribozyme populations were propagated under identical conditions and characterized when they reached apparent phenotypic plateaus; the populations that reached the highest plateau showed a near 100-fold improvement in DNA cleavage activity. A detailed characterization of the evolved response in these populations reveals at least two distinct phenotypic trajectories emerging as a result of the imposed selection. Not only do these distinct solutions exhibit differential DNA cleavage activity, but they also exhibit a very different correlation with a related, but unselected, phenotype: RNA cleavage activity. In turn, each of these trajectories is underwritten by differing genotypic profiles. This study underscores the complex network of possible trajectories through sequence space available to an evolving population and uncovers the diversity of solutions that result when the process of experimental evolution is repeated multiple times in a simple, engineered system.

Base Sequence↗

PubMed1999

Simple tandem repeat polymorphisms in the neuronal nitric oxide synthase gene in different ethnic populations.

Allelic frequencies of a CA dinucleotide repeat in exon 29 and an intronic AAT trinucleotide repeat in the neuronal nitric oxide synthase (NOS1) gene were determined by simple sequence length polymorphism (SSLP) in 305 American-Caucasian and 105 African-American healthy subjects. There were highly significant differences in allele frequencies between the two ethnically diverse study populations.

Alleles↗