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Biomedical subjects

J Meyne

Publications and source records attributed to J Meyne.

At least 37 records · Page 2Linked to original sources
PubMed1990

Determining the origins and the structural aberrations of small marker chromosomes in two cases of 45,X/46,X, + mar by use of chromosome-specific DNA probes.

A 17-year-old girl (S.M.) and a 13-year-old girl (C.L.) both with Ullrich-Turner syndrome (UTS) were found to have 45,X/46,X, + mar mosaicism. The marker chromosomes in both patients were very small in size. In S.M. the marker chromosome was present in 80% of phytohemagglutinin-stimulated lymphocytes, 28% of skin fibroblasts, and 11-20% of gonadal fibroblasts. In C.L., the small marker chromosome was found in 50% of stimulated lymphocytes. S.M. is of normal height, but C.L. is short. Molecular hybridization with a number of Y-specific DNA probes demonstrated their presence in S.M. but absence in C.L. In situ hybridization with Y-specific and X-centromere-specific DNA probes confirmed the Y origin of the marker chromosome in S.M. and the X origin of the minute chromosome in C.L. Biotinylated centromere and telomere probes were also used for in situ hybridization to show the presence of centromeric and telomeric sequences in the Y-marker chromosome, suggesting that the deletion of this marker chromosome is interstitial.

Adolescent↗
PubMed1990

Distribution of non-telomeric sites of the (TTAGGG)n telomeric sequence in vertebrate chromosomes.

The intrachromosomal distribution of non-telomeric sites of the (TTAGGG)n telomeric repeat was determined for 100 vertebrate species. The most common non-telomeric location of this sequence was in the pericentric regions of chromosomes. A variety of species showed relatively large amounts of this sequence present within regions of constitutive heterochromatin. We discuss possible relationships between the non-telomeric distribution of the (TTAGGG)n sequence and the process of karyotype evolution, during which these sites may provide potential new telomeres.

Amphibians↗
PubMed1989

Chromosome banding analysis by slit-scan flow cytometry.

We have investigated the use of fluorescence banding patterns for the resolution of metaphase chromosomes by slit-scan flow cytometry. Fluorescence scans of R-banded chromosomes have been obtained for the entire human karyotype. Metaphase chromosomes were R-banded in suspension by staining with chromomycin A3 after hypotonic treatment in Ohnuki's buffer. Specific fluorescent landmark bands were detected for human chromosomes 1-12. Scans obtained for chromosomes 13-22 did not contain sufficient information for classification. Characteristic fluorescence patterns for human chromosomes 1 and 3 provided the clearest evidence for the detection of R-bands by slit-scan flow cytometry. Specific patterns were detected for human chromosomes 9-12 in which the number and placement of the fluorescent bands served as classifiers.

Cell Line↗
PubMed1989

Labeling of human centromeres using an alphoid DNA consensus sequence: application to the scoring of chromosome aberrations.

Precise identification of centromeres is required for accurate scoring of asymmetrical chromosome aberrations, such as dicentrics. The centromeric regions of all human chromosomes can be labeled by in situ hybridization of a 30 nucleotide oligomer having the sequence of a conserved region of an alphoid DNA consensus sequence. Fluorescent detection of the hybridized probe allows rapid identification of centromeres and accurate scoring of dicentrics, multicentrics, acentric fragments, and the centromeric content of ring chromosomes. This procedure provides a novel approach for scoring these complex chromosome aberrations, particularly damage induced by radiation or radiomimetic agents.

Centromere↗
PubMed1989

Human chromosome-specific repetitive DNA probes: targeting in situ hybridization to chromosome 17 with a 42-base-pair alphoid DNA oligomer.

The pericentric region of human chromosome 17 was targeted for specific in situ hybridization of the alphoid DNA subfamily enriched on this chromosome. A recombinant DNA clone containing the entire higher order chromosome 17 alphoid repeat preferentially hybridized to the pericentric region of chromosome 17, but frequently cross-hybridized to other chromosomes under normal stringency conditions. Chromosomal specificity, after in situ hybridization to metaphase spreads and interphase nuclei, was improved by using a subclone containing predominantly monomer 1 of the higher order repeat. Further improvement was achieved by synthesizing a 42-nucleotide oligomer of a divergent region of monomer 1. Southern blot analysis confirmed the improved specificity of the shorter probes. Reducing the potential of repetitive DNA probes to cross-hybridize increases the usefulness of the probes, especially when they are used for localizing individual chromosomes in interphase nuclei.

Base Sequence↗
PubMed1989

The distribution of interspersed repetitive DNA sequences in the human genome.

The distribution of interspersed repetitive DNA sequences in the human genome has been investigated, using a combination of biochemical, cytological, computational, and recombinant DNA approaches. "Low-resolution" biochemical experiments indicate that the general distribution of repetitive sequences in human DNA can be adequately described by models that assume a random spacing, with an average distance of 3 kb. A detailed "high-resolution" map of the repetitive sequence organization along 400 kb of cloned human DNA, including 150 kb of DNA fragments isolated for this study, is consistent with this general distribution pattern. However, a higher frequency of spacing distances greater than 9.5 kb was observed in this genomic DNA sample. While the overall repetitive sequence distribution is best described by models that assume a random distribution, an analysis of the distribution of Alu repetitive sequences appearing in the GenBank sequence database indicates that there are local domains with varying Alu placement densities. In situ hybridization to human metaphase chromosomes indicates that local density domains for Alu placement can be observed cytologically. Centric heterochromatin regions, in particular, are at least 50-fold underrepresented in Alu sequences. The observed distribution for repetitive sequences in human DNA is the expected result for sequences that transpose throughout the genome, with local regions of "preference" or "exclusion" for integration.

Chromosome Mapping↗
PubMed1989

Cloning human telomeric DNA fragments into Saccharomyces cerevisiae using a yeast-artificial-chromosome vector.

Telomeric fragments of human DNA ranging in size from 50 to 250 kilobases were cloned into Saccharomyces cerevisiae using a yeast-artificial-chromosome (YAC) vector. Six human-telomeric YAC (HTY) strains were selected by virtue of the specific hybridization of their DNA with the human telomeric terminal-repeat sequence (TTAGGG)n, and the telomeric localization of this sequence within each YAC was demonstrated by its sensitivity to nuclease BAL-31. In situ hybridization of DNA from three of these HTY strains with human metaphase chromosomes yielded discrete patterns of hybridization signals at the telomeres of a limited number of human chromosomes, different for each clone. DNA from selected cosmid subclones of one of the HTY strains was used to localize the origin of the cloned telomeric DNA by in situ hybridization to the tip of the long arm of chromosome 7.

Base Sequence↗
PubMed1989

Conservation of the human telomere sequence (TTAGGG)n among vertebrates.

To determine the evolutionary origin of the human telomere sequence (TTAGGG)n, biotinylated oligodeoxynucleotides of this sequence were hybridized to metaphase spreads from 91 different species, including representative orders of bony fish, reptiles, amphibians, birds, and mammals. Under stringent hybridization conditions, fluorescent signals were detected at the telomeres of all chromosomes, in all 91 species. The conservation of the (TTAGGG)n sequence and its telomeric location, in species thought to share a common ancestor over 400 million years ago, strongly suggest that this sequence is the functional vertebrate telomere.

Animals↗
PubMed1989

Telomere staining of human chromosomes and the mechanism of radiation-induced dicentric formation.

The majority of models of radiation action developed over the past half century hold that the curvilinear dose responses exhibited by eukaryotic cells to sparsely ionizing radiations result from the interaction of pairs of lesions produced in sensitive targets of the cell. Within this conceptual framework, chromosomal exchange aberrations (e.g., interchanges) are believed to occur through the interaction of damaged sites on both chromosomes participating in the exchange. In contrast, the model proposed by Chadwick and Leenhouts (as well as some other models) suggests that such exchanges arise from initial radiation damage to only one chromosome, which then becomes associated with an undamaged chromosome. A particular aspect of this theory is that asymmetrical exchanges, such as dicentrics, may be formed from the rejoining of a broken end of one chromosome to the telomere of another. By using a DNA probe that specifically hybridizes to the telomeric region of human chromosomes, we were able to test this assertion directly. After scanning more than 200 dicentrics produced in normal human fibroblasts by 6 Gy of 60Co gamma rays, virtually none were found that contained telomeres located between the centromeres of this aberration type. Therefore, since the proposed telomere-break rejoining process, per se, is not necessarily a central element of the Chadwick-Leenhouts model, we suggest the theory be modified to exclude this mechanism.

Chromosome Aberrations↗
PubMed1988

Isolation and molecular characterization of a highly polymorphic centromeric tandem repeat in the family Falconidae.

An abundant tandem repeat has been cloned from genomic DNA of the merlin (Falco columbarius). The cloned sequence is 174 bp in length, and maps by in situ hybridization to the centromeric regions of several of the large chromosomes within the merlin karyotype. Complementary sequences have been identified within a variety of falcon species; these sequences are either absent or in very low copy number in the family Accipitridae. The cloned merlin repeat reveals highly polymorphic restriction patterns in the peregrine falcon (Falco peregrinus). These polymorphisms, which have been shown to be stably inherited within a family of captive peregrines, can be used to differentiate the Greenland and Argentina populations of this endangered raptor species.

Animals↗
PubMed1988

A highly conserved repetitive DNA sequence, (TTAGGG)n, present at the telomeres of human chromosomes.

A highly conserved repetitive DNA sequence, (TTAGGG)n, has been isolated from a human recombinant repetitive DNA library. Quantitative hybridization to chromosomes sorted by flow cytometry indicates that comparable amounts of this sequence are present on each human chromosome. Both fluorescent in situ hybridization and BAL-31 nuclease digestion experiments reveal major clusters of this sequence at the telomeres of all human chromosomes. The evolutionary conservation of this DNA sequence, its terminal chromosomal location in a variety of higher eukaryotes (regardless of chromosome number or chromosome length), and its similarity to functional telomeres isolated from lower eukaryotes suggest that this sequence is a functional human telomere.

Base Sequence↗
PubMed1988

Characterization of human heterochromatin by in situ hybridization with satellite DNA clones.

Biotinylated DNA from two satellite-related, repetitive DNA clones, pHuR 98 and pHuR 195 (specific for chromosomes 9 and 16, respectively), and from a Y-specific clone, pY-3.4A, were hybridized to human metaphase chromosomes using fluoresceinated avidin to detect binding. The chromosomes were simultaneously counterstained with distamycin-DAPI to identify the AT-rich heterochromatin of chromosomes 1, 9, 15, 16, and the Y chromosome. With this method, clear results were obtained under both normal and low stringency conditions, allowing hybridization between molecules sharing 80-85% and 60-65% identity, respectively. Thus, additional sites related to the probes could be identified. A close relationship was shown between the heterochromatin of chromosomes 1 and 16, both hybridizing with clone pHuR 195 under low stringency. Hybridization with clone pHuR 98 was highly specific for chromosome 9, even under low stringency. A relationship between chromosomes 9, 15, and the Y chromosome, however, was shown by hybridization with clone pY-3.4A. The chromosomal distribution of the three repetitive DNA clones used in this study, and data from the literature, are in accordance with the distribution of the heterochromatin types characterized by staining with different fluorescent dyes and dye combinations. Furthermore, our sequence data for clones pHuR 98 and pHuR 195 may explain the fluorescent properties on which the cytogenetic classification of the heterochromatin is based.

Avidin↗
PubMed1988

Fragile sites, telomeric DNA sequences, B chromosomes, and DNA content in raccoon dogs, Nyctereutes procyonoides, with comparative notes on foxes, coyote, wolf, and raccoon.

Earlier studies of the genus Nyctereutes disclosed two subspecies of differing chromosome numbers accompanied by B chromosomes. To further define the relationship of these subspecies to each other, and to other carnivores, and to learn more about the structure and function of their chromosomes, we characterized and compared the genomes in terms of DNA content by flow cytometry, fragile sites induced by aphidicolin, and telomere sequences using biotinylated DNA probes detected with fluorescence. We also characterized the B chromosomes of these two subspecies.

Animals↗
PubMed1987

Human chromosome-specific repetitive DNA sequences: novel markers for genetic analysis.

Two recombinant DNA clones that are localized to single human chromosomes were isolated from a human repetitive DNA library. Clone pHuR 98, a variant satellite 3 sequence, specifically hybridizes to chromosome position 9qh. Clone pHuR 195, a variant satellite 2 sequence, specifically hybridizes to chromosome position 16qh. These locations were determined by fluorescent in situ hybridization to metaphase chromosomes, and confirmed by DNA hybridizations to human chromosomes sorted by flow cytometry. Pulsed field gel electrophoresis analysis indicated that both sequences exist in the genome as large DNA blocks. In situ hybridization to intact interphase nuclei showed a well-defined, localized organization for both DNA sequences. The ability to tag specific human autosomal chromosomes, both at metaphase and in interphase nuclei, allows novel molecular cytogenetic analyses in numerous basic research and clinical studies.

Base Sequence↗
PubMed1986

Alterations in the DNA metabolism of MCa-11 mouse mammary tumor cells grown in vivo and in vitro.

Mouse mammary carcinoma (MCa-11) cells were grown in vitro in exponential, plateau-fed, and starved monolayer cultures or as 100-, 250-, and 500-microns tissue culture spheroids, and in vivo as small (4-mm diameter) and large (12-mm diameter) tumors. In all of these forms, the growth rates of the MCa-11 cells were found to decrease after an initial rapid proliferation of a relatively small number of cells. The DNA distributions of these cells during different rates of growth in vitro and in vivo, as well as the proportion and intensity of labeling of the S-phase cells with [3H]thymidine and [3H]deoxyuridine, were measured by flow and absorption cytometry. We found that significant numbers of MCa-11 cells remained in S phase, even after the growth rates in vivo and in vitro had slowed. However, as growth rates decreased, the intensity and proportion of S-phase cells labeled with exogenous DNA precursors decreased. We conclude that progressive alterations, including possible slowing and cessation, of replicative DNA synthesis occur in S-phase tumor cells as the metabolic constraints on tumor growth are increased.

Animals↗