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Biomedical subjects

J Meyne

Publications and source records attributed to J Meyne.

At least 19 recordsLinked to original sources
PubMed1995

FISH analysis of the telomere sequences of bulldog ants (Myrmecia: formicidae).

Chromosomes from several species of ants from the genus Myrmecia were hybridized with deoxyoligomer probes of either (T2AG2)7, the putative insect telomere repeat sequence, or (T2AG3)7, the vertebrate telomere repeat sequence. While both sequences hybridized over a range of stringency conditions, (T2AG2)n was clearly the predominant sequence at the termini of the Myrmecia chromosomes. No interstitial sites of either sequence were detected. The genus Myrmecia has a wide range of karyotypes, with chromosome numbers ranging from 2n=2-84. It has been hypothesized that the ancestral karyotype was 2n=4 and karyotype evolution proceeded with an increase in chromosome number. In the absence of detectable interstitial sites of telomere sequence, it is interesting to speculate on the origin of the new telomeres as the chromosome numbers increased.

Animals↗
PubMed1995

Direction of DNA sequences within chromatids determined using strand-specific FISH.

The 5' to 3' direction of DNA strands within chromatids of metaphase chromosomes can be determined by using simultaneous hybridization of a single strand of the telomere probe and a single strand of a repetitive sequence to slides pretreated for strand-specific hybridization. The telomere probe identifies the direction of the DNA helical strand remaining in each chromatid of the metaphase chromosomes. The direction of the repetitive sequence is then determined from the direction of the strand to which it hybridizes. This method was used to determine the 5' to 3' direction of three repetitive DNA sequences, each for a different human repeat family.

Base Sequence↗
PubMed1994

Identification of trisomy in Macaca fascicularis by fluorescence in situ hybridization with a human chromosome 13 DNA library.

A juvenile macaque monkey with abnormal phenotypic and behavioral features was studied cytogenetically. An additional autosome was found in over 90% of the animal's cultured cells. This chromosome, subsequently identified as number 16 in the macaque karyotype by G-banding, was shown to be mostly homologous with human chromosome 13 using fluorescence in situ hybridization of a human chromosome specific cosmid library. Although the monkey, now deceased, exhibited some abnormal physical and behavioral features, none of the severe clinical characteristics associated with human chromosome 13 trisomy were apparent. We suggest that the incomplete expression of 13-trisomy observed could result if the macaque chromosome were deficient in some of the region(s) of chromosome 13 common to humans affected with the disorder.

Animals↗
PubMed1994

Chromosome localization and orientation of the simple sequence repeat of human satellite I DNA.

The predominant chromosomal locations of human satellite I DNA were detected using fluorescent in situ hybridization (FISH). Synthetic deoxyoligonucleotides designed from consensus sequences of the simple sequence repeats of satellite 1 were used as probes. The most abundant satellite I repeat, the -A-B-A-B-A- form, is located at the pericentromeric regions of chromosomes 3, 4, 13, 14, 15, 21, and 22. The less abundant -B-B-B-form was not detected on chromosome 4, but was present at all the other locations. A variation of FISH that allows strand-specific hybridization of single-stranded probes (CO-FISH) determined that the human satellite I sequences are predominantly arranged in head-to-tail fashion along the DNA strand.

Base Sequence↗
PubMed1992

SV40 T antigen induced chromosomal changes reflect a process that is both clastogenic and aneuploidogenic and is ongoing throughout neoplastic progression of human fibroblasts.

In human fibroblasts, the expression of SV40 large T antigen is known to cause a variety of chromosomal aberrations and especially dicentric chromosomes. In some cases, the later aberrations have been reported to be reversible telomeric associations. We report here aberration and chromosome number studies of twenty-nine T antigen positive lineages, studied from their initiation by transfection of T antigen sequences into human diploid fibroblasts, until crisis or immortalization occurred or, in some cases until the lines became tumorigenic in nude mice. The data show that T antigen consistently produced chromosomal instability of both number and structure by an active process that began before transformation indicators were positive and continued throughout neoplastic progression. The most frequently observed aberrations were dicentric chromosomes, which were shown to be true dicentrics by examination by in situ hybridization with telomeric sequences. These data are consistent with the hypothesis that T antigen causes human fibroblasts to become neoplastically transformed by successive rounds of chromosomal mutation and lineage evolution.

Antigens, Polyomavirus Transforming↗
PubMed1992

Highly conserved repetitive DNA sequences are present at human centromeres.

Highly conserved repetitive DNA sequence clones, largely consisting of (GGAAT)n repeats, have been isolated from a human recombinant repetitive DNA library by high-stringency hybridization with rodent repetitive DNA. This sequence, the predominant repetitive sequence in human satellites II and III, is similar to the essential core DNA of the Saccharomyces cerevisiae centromere, centromere DNA element (CDE) III. In situ hybridization to human telophase and Drosophila polytene chromosomes shows localization of the (GGAAT)n sequence to centromeric regions. Hyperchromicity studies indicate that the (GGAAT)n sequence exhibits unusual hydrogen bonding properties. The purine-rich strand alone has the same thermal stability as the duplex. Hyperchromicity studies of synthetic DNA variants indicate that all sequences with the composition (AATGN)n exhibit this unusual thermal stability. DNA-mobility-shift assays indicate that specific HeLa-cell nuclear proteins recognize this sequence with a relative affinity greater than 10(5). The extreme evolutionary conservation of this DNA sequence, its centromeric location, its unusual hydrogen bonding properties, its high affinity for specific nuclear proteins, and its similarity to functional centromeres isolated from yeast suggest that this sequence may be a component of the functional human centromere.

Animals↗
PubMed1992

Interstitial hybridization sites of the (TTAGGG)n telomeric sequence on the chromosomes of some North American hylid frogs.

Interstitial hybridization sites for the (TTAGGG)n telomeric repeat sequence were present in all seven species of hylid frogs examined and in a triploid hybrid between two of the species. Intra- and interspecific differences and similarities in hybridization sites agreed with what is known about the systematics of these species. Chromosome fusions, fissions, and inversions do not appear to have played a role in the evolution of the interstitial sites for the telomeric repeat in the species examined.

Animals↗
PubMed1991

The centromere-kinetochore complex: a repeat subunit model.

The three-dimensional structure of the kinetochore and the DNA/protein composition of the centromere-kinetochore region was investigated using two novel techniques, caffeine-induced detachment of unreplicated kinetochores and stretching of kinetochores by hypotonic and/or shear forces generated in a cytocentrifuge. Kinetochore detachment was confirmed by EM and immunostaining with CREST autoantibodies. Electron microscopic analyses of serial sections demonstrated that detached kinetochores represented fragments derived from whole kinetochores. This was especially evident for the seven large kinetochores in the male Indian muntjac that gave rise to 80-100 fragments upon detachment. The kinetochore fragments, all of which interacted with spindle microtubules and progressed through the entire repertoire of mitotic movements, provide evidence for a subunit organization within the kinetochore. Further support for a repeat subunit model was obtained by stretching or uncoiling the metaphase centromere-kinetochore complex by hypotonic treatments. When immunostained with CREST autoantibodies and subsequently processed for in situ hybridization using synthetic centromere probes, stretched kinetochores displayed a linear array of fluorescent subunits arranged in a repetitive pattern along a centromeric DNA fiber. In addition to CREST antigens, each repetitive subunit was found to bind tubulin and contain cytoplasmic dynein, a microtubule motor localized in the zone of the corona. Collectively, the data suggest that the kinetochore, a plate-like structure seen by EM on many eukaryotic chromosomes is formed by the folding of a linear DNA fiber consisting of tandemly repeated subunits interspersed by DNA linkers. This model, unlike any previously proposed, can account for the structural and evolutional diversity of the kinetochore and its relationship to the centromere of eukaryotic chromosomes of many species.

Animals↗
PubMed1991

Ribosomal RNA gene site polymorphism in Bufo terrestris.

Individual specimens of Bufo terrestris were discovered that possessed ribosomal gene locations in addition to those normally found. Every specimen from an island population that was examined had extra sites, whereas fewer individuals from coastal mainland populations and none from inland populations had them. Although the extra ribosomal gene locations probably did not arise through gross structural chromosome rearrangements, their origin remains unclear.

Animals↗
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↗