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Uno Y, Matsubara K, Inoue J, Inazawa J, Shinohara A, Koshimoto C, Ichiyanagi K, Matsuda Y. Diversity and Evolution of Highly Repetitive DNA Sequences Constituting Chromosome Site-Specific Heterochromatin in Two Gerbillinae Species. Cytogenet Genome Res 2023; 163:42-51. [PMID: 37708873 DOI: 10.1159/000533716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 08/18/2023] [Indexed: 09/16/2023] Open
Abstract
Constitutive heterochromatin, consisting of repetitive sequences, diverges very rapidly; therefore, its nucleotide sequences and chromosomal distributions are often largely different, even between closely related species. The chromosome C-banding patterns of two Gerbillinae species, Meriones unguiculatus and Gerbillus perpallidus, vary greatly, even though they belong to the same subfamily. To understand the evolution of C-positive heterochromatin in these species, we isolated highly repetitive sequences, determined their nucleotide sequences, and characterized them using chromosomal and filter hybridization. We obtained a centromeric repeat (MUN-HaeIII) and a chromosome 13-specific repeat (MUN-EcoRI) from M. unguiculatus. We also isolated a centromeric/pericentromeric repeat (GPE-MBD) and an interspersed-type repeat that was predominantly amplified in the X and Y chromosomes (GPE-EcoRI) from G. perpallidus. GPE-MBD was found to contain a 17-bp motif that is essential for binding to the centromere-associated protein CENP-B. This indicates that it may play a role in the formation of a specified structure and/or function of centromeres. The nucleotide sequences of the three sequence families, except GPE-EcoRI, were conserved only in Gerbillinae. GPE-EcoRI was derived from the long interspersed nuclear elements 1 retrotransposon and showed sequence homology throughout Muridae and Cricetidae species, indicating that the repeat sequence occurred at least in the common ancestor of Muridae and Cricetidae. Due to a lack of assembly data of highly repetitive sequences constituting heterochromatin in whole-genome sequences of vertebrate species published to date, the knowledge obtained in this study provides useful information for a deep understanding of the evolution of repetitive sequences in not only rodents but also in mammals.
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Affiliation(s)
- Yoshinobu Uno
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Kazumi Matsubara
- Department of Environmental Biology, College of Bioscience and Biotechnology, Chubu University, Kasugai, Japan
| | - Jun Inoue
- Department of Molecular Cytogenetics, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
- Bioresource Research Center, Tokyo Medical and Dental University, Tokyo, Japan
| | - Johji Inazawa
- Department of Molecular Cytogenetics, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
- Bioresource Research Center, Tokyo Medical and Dental University, Tokyo, Japan
| | - Akio Shinohara
- Department of Biotechnology, Frontier Science Research Center, University of Miyazaki, Miyazaki, Japan
| | - Chihiro Koshimoto
- Department of Biotechnology, Frontier Science Research Center, University of Miyazaki, Miyazaki, Japan
| | - Kenji Ichiyanagi
- Department of Animal Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Yoichi Matsuda
- Department of Animal Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
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2
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Shkumatov A, Kuznyetsov V, Cieslak J, Ilkevitch Y, Verlinsky Y. Obtaining metaphase spreads from single blastomeres for PGD of chromosomal rearrangements. Reprod Biomed Online 2007; 14:498-503. [PMID: 17425834 DOI: 10.1016/s1472-6483(10)60899-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
It has previously been shown that it is possible to obtain metaphase chromosomes from single blastomeres converted into metaphase in the cytoplasm of a mouse zygote. This method is highly labour intensive and cannot be performed outside the preimplantation genetic diagnosis (PGD) laboratory, so to overcome these limitations, a method was developed for obtaining metaphase spreads from single biopsied blastomeres using different chemicals. The substances tested were calyculin A, caffeine, paclitaxel and colcemid in a total of 496 disaggregated and 234 biopsied blastomeres from day 3 embryos. It was demonstrated that the optimal method involved a combined use of 'selective biopsy' (selection of the biopsied blastomere according to morphological criteria) and exposure to caffeine. This resulted in shortening the mean incubation time of biopsied blastomeres, with a metaphase formation rate of 80%. The method is simple for obtaining metaphases from single blastomeres, and may be implemented in clinical practice of PGD for structural rearrangements.
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Affiliation(s)
- Artem Shkumatov
- Reproductive Genetics Institute, 2825 North Halsted Street, Chicago, IL 60657, USA
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3
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Yamada K, Kamimura E, Kondo M, Tsuchiya K, Nishida-Umehara C, Matsuda Y. New families of site-specific repetitive DNA sequences that comprise constitutive heterochromatin of the Syrian hamster (Mesocricetus auratus, Cricetinae, Rodentia). Chromosoma 2005; 115:36-49. [PMID: 16328536 DOI: 10.1007/s00412-005-0012-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2005] [Revised: 05/30/2005] [Accepted: 06/09/2005] [Indexed: 11/25/2022]
Abstract
We molecularly cloned new families of site-specific repetitive DNA sequences from BglII- and EcoRI-digested genomic DNA of the Syrian hamster (Mesocricetus auratus, Cricetrinae, Rodentia) and characterized them by chromosome in situ hybridization and filter hybridization. They were classified into six different types of repetitive DNA sequence families according to chromosomal distribution and genome organization. The hybridization patterns of the sequences were consistent with the distribution of C-positive bands and/or Hoechst-stained heterochromatin. The centromeric major satellite DNA and sex chromosome-specific and telomeric region-specific repetitive sequences were conserved in the same genus (Mesocricetus) but divergent in different genera. The chromosome-2-specific sequence was conserved in two genera, Mesocricetus and Cricetulus, and a low copy number of repetitive sequences on the heterochromatic chromosome arms were conserved in the subfamily Cricetinae but not in the subfamily Calomyscinae. By contrast, the other type of repetitive sequences on the heterochromatic chromosome arms, which had sequence similarities to a LINE sequence of rodents, was conserved through the three subfamilies, Cricetinae, Calomyscinae and Murinae. The nucleotide divergence of the repetitive sequences of heterochromatin was well correlated with the phylogenetic relationships of the Cricetinae species, and each sequence has been independently amplified and diverged in the same genome.
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Affiliation(s)
- Kazuhiko Yamada
- Laboratory of Animal Cytogenetics, Creative Research Initiative Sousei, Hokkaido University, Sapporo, Japan
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Cortés F, Mateos S, Pastor N, Domínguez I. Toward a comprehensive model for induced endoreduplication. Life Sci 2004; 76:121-35. [PMID: 15519359 DOI: 10.1016/j.lfs.2004.08.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2004] [Accepted: 08/28/2004] [Indexed: 11/25/2022]
Abstract
Both the biological significance and the molecular mechanism of endoreduplication (END) have been debated for a long time by cytogeneticists and researchers into cell cycle enzymology and dynamics alike. Mainly due to the fact that a wide variety of agents have been reported as able to induce endoreduplication and the diversity of cell types where it has been described, until now no clear or unique mechanism of induction of this phenomenon, rare in animals but otherwise quite common in plants, has been proposed. DNA topoisomerase II (topo II), plays a major role in mitotic chromosome segregation after DNA replication. The classical topo II poisons act by stabilizing the enzyme in the so-called cleavable complex and result in DNA damage as well as END, while the true catalytic inhibitors, which are not cleavable-complex-stabilizers, do induce END without concomitant DNA and chromosome damage. Taking into account these observations on the induction of END by drugs that interfere with topo II, together with our recently obtained evidence that the nature of DNA plays an important role for chromosome segregation [Cortes, F., Pastor, N., Mateos, S., Dominguez, I., 2003. The nature of DNA plays a role in chromosome segregation: endoreduplication in halogen-substituted chromosomes. DNA Repair 2, 719-726.], a straightforward model is proposed in which the different mechanisms leading to induced END are considered.
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Affiliation(s)
- Felipe Cortés
- Department of Cell Biology, Faculty of Biology of Seville, Avenue Reina Mercedes 6, E-41012 Seville, Spain.
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5
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Sadygov RG, Liu H, Yates JR. Statistical Models for Protein Validation Using Tandem Mass Spectral Data and Protein Amino Acid Sequence Databases. Anal Chem 2004; 76:1664-71. [PMID: 15018565 DOI: 10.1021/ac035112y] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The purpose of this work is to develop and verify statistical models for protein identification using peptide identifications derived from the results of tandem mass spectral database searches. Recently we have presented a probabilistic model for peptide identification that uses hypergeometric distribution to approximate fragment ion matches of database peptide sequences to experimental tandem mass spectra. Here we apply statistical models to the database search results to validate protein identifications. For this we formulate the protein identification problem in terms of two independent models, two-hypothesis binomial and multinomial models, which use the hypergeometric probabilities and cross-correlation scores, respectively. Each database search result is assumed to be a probabilistic event. The Bernoulli event has two outcomes: a protein is either identified or not. The probability of identifying a protein at each Bernoulli event is determined from relative length of the protein in the database (the null hypothesis) or the hypergeometric probability scores of the protein's peptides (the alternative hypothesis). We then calculate the binomial probability that the protein will be observed a certain number of times (number of database matches to its peptides) given the size of the data set (number of spectra) and the probability of protein identification at each Bernoulli event. The ratio of the probabilities from these two hypotheses (maximum likelihood ratio) is used as a test statistic to discriminate between true and false identifications. The significance and confidence levels of protein identifications are calculated from the model distributions. The multinomial model combines the database search results and generates an observed frequency distribution of cross-correlation scores (grouped into bins) between experimental spectra and identified amino acid sequences. The frequency distribution is used to generate p-value probabilities of each score bin. The probabilities are then normalized with respect to score bins to generate normalized probabilities of all score bins. A protein identification probability is the multinomial probability of observing the given set of peptide scores. To reduce the effect of random matches, we employ a marginalized multinomial model for small values of cross-correlation scores. We demonstrate that the combination of the two independent methods provides a useful tool for protein identification from results of database search using tandem mass spectra. A receiver operating characteristic curve demonstrates the sensitivity and accuracy level of the approach. The shortcomings of the models are related to the cases when protein assignment is based on unusual peptide fragmentation patterns that dominate over the model encoded in the peptide identification process. We have implemented the approach in a program called PROT_PROBE.
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Affiliation(s)
- Rovshan G Sadygov
- Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037, USA
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Van Hooser AA, Ouspenski II, Gregson HC, Starr DA, Yen TJ, Goldberg ML, Yokomori K, Earnshaw WC, Sullivan KF, Brinkley BR. Specification of kinetochore-forming chromatin by the histone H3 variant CENP-A. J Cell Sci 2001; 114:3529-42. [PMID: 11682612 DOI: 10.1242/jcs.114.19.3529] [Citation(s) in RCA: 199] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mechanisms that specify precisely where mammalian kinetochores form within arrays of centromeric heterochromatin remain largely unknown. Localization of CENP-A exclusively beneath kinetochore plates suggests that this distinctive histone might direct kinetochore formation by altering the structure of heterochromatin within a sub-region of the centromere. To test this hypothesis, we experimentally mistargeted CENP-A to non-centromeric regions of chromatin and determined whether other centromere-kinetochore components were recruited. CENP-A-containing non-centromeric chromatin assembles a subset of centromere-kinetochore components, including CENP-C, hSMC1, and HZwint-1 by a mechanism that requires the unique CENP-A N-terminal tail. The sequence-specific DNA-binding protein CENP-B and the microtubule-associated proteins CENP-E and HZW10 were not recruited, and neocentromeric activity was not detected. Experimental mistargeting of CENP-A to inactive centromeres or to acentric double-minute chromosomes was also not sufficient to assemble complete kinetochore activity. The recruitment of centromere-kinetochore proteins to chromatin appears to be a unique function of CENP-A, as the mistargeting of other components was not sufficient for assembly of the same complex. Our results indicate at least two distinct steps in kinetochore assembly: (1) precise targeting of CENP-A, which is sufficient to assemble components of a centromere-prekinetochore scaffold; and (2) targeting of kinetochore microtubule-associated proteins by an additional mechanism present only at active centromeres.
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Affiliation(s)
- A A Van Hooser
- Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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Cimini D, Howell B, Maddox P, Khodjakov A, Degrassi F, Salmon E. Merotelic kinetochore orientation is a major mechanism of aneuploidy in mitotic mammalian tissue cells. J Cell Biol 2001; 153:517-27. [PMID: 11331303 PMCID: PMC2190575 DOI: 10.1083/jcb.153.3.517] [Citation(s) in RCA: 409] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In mitotic cells, an error in chromosome segregation occurs when a chromosome is left near the spindle equator after anaphase onset (lagging chromosome). In PtK1 cells, we found 1.16% of untreated anaphase cells exhibiting lagging chromosomes at the spindle equator, and this percentage was enhanced to 17.55% after a mitotic block with 2 microM nocodazole. A lagging chromosome seen during anaphase in control or nocodazole-treated cells was found by confocal immunofluorescence microscopy to be a single chromatid with its kinetochore attached to kinetochore microtubule bundles extending toward opposite poles. This merotelic orientation was verified by electron microscopy. The single kinetochores of lagging chromosomes in anaphase were stretched laterally (1.2--5.6-fold) in the directions of their kinetochore microtubules, indicating that they were not able to achieve anaphase poleward movement because of pulling forces toward opposite poles. They also had inactivated mitotic spindle checkpoint activities since they did not label with either Mad2 or 3F3/2 antibodies. Thus, for mammalian cultured cells, kinetochore merotelic orientation is a major mechanism of aneuploidy not detected by the mitotic spindle checkpoint. The expanded and curved crescent morphology exhibited by kinetochores during nocodazole treatment may promote the high incidence of kinetochore merotelic orientation that occurs after nocodazole washout.
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Affiliation(s)
- Daniela Cimini
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
- Centro Genetica Evoluzionistica CNR, c/o Department of Genetics and Molecular Biology, University of Rome “La Sapienza,” 4-00185 Rome, Italy
| | - Bonnie Howell
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Paul Maddox
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Alexey Khodjakov
- Division of Molecular Medicine, Wadsworth Center, New York State Department of Health, Albany, New York 12201
| | - Francesca Degrassi
- Centro Genetica Evoluzionistica CNR, c/o Department of Genetics and Molecular Biology, University of Rome “La Sapienza,” 4-00185 Rome, Italy
| | - E.D. Salmon
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
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8
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Van Hooser A, Brinkley WR. Methods for in situ localization of proteins and DNA in the centromere-kinetochore complex. Methods Cell Biol 1999; 61:57-80. [PMID: 9891309 DOI: 10.1016/s0091-679x(08)61975-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Affiliation(s)
- A Van Hooser
- Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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9
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Houben A, Brandes A, Pich U, Manteuffel R, Schubert I. Molecular-cytogenetic characterization of a higher plant centromere/kinetochore complex. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 1996; 93:477-484. [PMID: 24162338 DOI: 10.1007/bf00417938] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/1996] [Accepted: 01/19/1996] [Indexed: 06/02/2023]
Abstract
The centromeric region of a telocentric field bean chromosome that resulted from centric fission of the metacentric satellite chromosome was microdissected. The DNA of this region was amplified and biotinylated by degenerate oligonucleotide-primed polymerase chain reaction (DOP-PCR)/linker-adapter PCR. After fluorescence in situ hybridization (FISH) the entire chromosome complement of Vicia faba was labelled by these probes except for the nucleolus organizing region (NOR) and the interstitial heterochromatin, the chromosomes of V. sativa and V. narbonensis were only slightly labelled by the same probes. Dense uniform labelling was also observed when a probe amplified from a clearly delimited microdissected centromeric region of a mutant of Tradescantia paludosa was hybridized to T. paludosa chromosomes. Even after six cycles of subtractive hybridization between DNA fragments amplified from centromeric and acentric regions no sequences specifically located at the field bean centromeres were found among the remaining DNA. A mouse antiserum was produced which detected nuclear proteins of 33 kDa and 68 kDa; these were predominantly located at V. faba kinetochores during mitotic metaphase. DNA amplified from the chromatin fraction adsorbed by this serum out of the sonicated total mitotic chromatin also did not cause specific labelling of primary constrictions. From these results we conclude: (1) either centromere-specific DNA sequences are not very conserved among higher plants and are - at least in species with large genomes - intermingled with complex dispersed repetitive sequences that prevent the purification of the former, or (2) (some of) the dispersed repeats themselves specify the primary constrictions by stereophysical parameters rather than by their base sequence.
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Affiliation(s)
- A Houben
- Institut für Pflanzengenetik und Kulturpflanzenforschung, Corrensstrasse 3, D-06466, Gatersleben, Germany
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10
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Vig BK, Latour D, Brown M. Localization of anti-CENP antibodies and alphoid sequences in acentric heterochromatin in a breast cancer cell line. CANCER GENETICS AND CYTOGENETICS 1996; 88:118-25. [PMID: 8640719 DOI: 10.1016/0165-4608(95)00210-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Karyotype alterations are a hallmark of cancer cells. Of particular interest to our laboratory are the inactive centromeres and blocks of heterochromatin devoid of the accompanying centromere. When purified or monospecies anticentromere proteins (CENP) antibodies or the whole serum from scleroderma (crest) patients are applied to human chromosomes, the centromere region exhibits the label. When we treated MDA 435 cells with the anti-CENP-A, anti-CENP-B, or the whole serum, the label was apparent on heterochromatin pericentric to the active and inactive centromeres. Moreover, blocks of heterochromatin not associated with any centromere also exhibited the label. Anti-CENP-C, however, is more strictly confined to the centromere in discrete dots and is not detected on any region except the sites of active centromeres. Distribution of alpha sequences also shows a pattern compatible with its distribution in the heterochromatin. Apparently, the use of anti-CENP-A and anti-CENP-B antibodies or alphoid DNA may not detect either the centromere (primary constriction) or the kinetochore; CENP-C may be an exception.
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Affiliation(s)
- B K Vig
- Department of Biology, University of Nevada, Reno 89557-0015, USA
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11
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Lee C, Li X, Jabs EW, Court D, Lin CC. Human gamma X satellite DNA: an X chromosome specific centromeric DNA sequence. Chromosoma 1995; 104:103-12. [PMID: 8585987 DOI: 10.1007/bf00347692] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The cosmid clone, CX16-2D12, was previously localized to the centromeric region of the human X chromosome and shown to lack human X-specific alpha satellite DNA. A 1.2 kb EcoRI fragment was subcloned from the CX16-2D12 cosmid and was named 2D12/E2. DNA sequencing revealed that this 1,205 bp fragment consisted of approximately five tandemly repeated DNA monomers of 220 bp. DNA sequence homology between the monomers of 2D12/E2 ranged from 72.8% to 78.6%. Interestingly, DNA sequence analysis of the 2D12/E2 clone displayed a change in monomer unit orientation between nucleotide positions 585-586 from a "tail-to-head" arrangement to a "head-to-tail" configuration. This may reflect the existence of at least one inversion within this repetitive DNA array in the centromeric region of the human X chromosome. The DNA consensus sequence derived from a compilation of these 220 bp monomers had approximately 62% DNA sequence similarity to the previously determined gamma 8 satellite DNA consensus sequence. Comparison of the 2D12/E2 and gamma 8 consensus sequences revealed a 20 bp DNA sequence that was well conserved in both DNA consensus sequences. Slot-blot analysis revealed that this repetitive DNA sequence comprises approximately 0.015% of the human genome, similar to that found with gamma 8 satellite DNA. These observations suggest that this satellite DNA clone is derived from a subfamily of gamma satellite DNA and is thus designated gamma X satellite DNA. When genomic DNA from six unrelated males and two unrelated females was cut with SstI or HpaI and separated by pulsed-field gel electrophoresis, no restriction fragment length polymorphisms were observed for either gamma X (2D12/E2) or gamma 8 (50E4) probes. Fluorescence in situ hybridization localized the 2D12/E2 clone to the lateral sides of the primary constriction specifically on the human X chromosome.
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Affiliation(s)
- C Lee
- Department of Laboratory Medicine and Pathology, University of Alberta and the University of Alberta Hospitals, Edmonton, Alberta, Canada, T6G 2B7
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12
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Paweletz N, Finze EM, Schroeter D, Enulescu M, Knehr M. Immunoelectron microscopic studies on centromere-kinetochore complexes detached from chromosomes. Chromosome Res 1995; 3:235-8. [PMID: 7606361 DOI: 10.1007/bf00713048] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The centromere-kinetochore complexes of Chinese hamster ovary (CHO) cells were detached and separated from the condensed chromatin by treatment with hydroxyurea and caffeine. By labelling the complex for immunoelectron microscopy (immuno-EM) with a mixture of antibodies against centromere proteins (anti-CENP-A, -B, -C) in some cells, we could demonstrate complete detachment of the complexes. No remnants were left at the bulk of condensed chromatin in these cells. In some mitotic cells complex and chromatin were found side by side. It could be shown that the fine structure of the separated material of the complex differs significantly from that of the rest of chromatin. The complex consists of proteins and DNA. This leads us to suppose that the organization of chromatin in the centromere-kinetochore complex is different.
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Affiliation(s)
- N Paweletz
- Research Program IV, German Cancer Research Center, Heidelberg
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13
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Vig BK, Latour D, Frankovich J. Dissociation of minor satellite from the centromere in mouse. J Cell Sci 1994; 107 ( Pt 11):3091-5. [PMID: 7535306 DOI: 10.1242/jcs.107.11.3091] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The minor satellite DNA of mouse is believed to constitute the centromere. We report that centromeres of some chromosomes in the Cl1D cells of mouse are not associated with this DNA even though the latter is present on these chromosomes. The satellite DNA was detected distally from the centromere and could not be mistaken as a component of the centromere. We also report that the site of the primary constriction may not always coincide with the site of the anti-kinetochore antibody reaction. Whereas the regions containing the major satellite decondense upon treatment with bisbenzimidazole (Hoechst 33258), the sites carrying minor satellite resist decondensing.
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Affiliation(s)
- B K Vig
- Department of Biology, University of Nevada, Reno 89557-0015
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14
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Abstract
It is becoming increasingly clear that the underlying base composition of the DNA located in the centromere region is vastly different in different organisms. The chromosomes of related species or even the various chromosomes of the same species differ widely in their so-called centromeric DNA. Yet all centromeres appear physically alike and perform similar functions. The present communication proposes that the physical properties of the centromere are not due to its base composition but due to stereophysical make-up of the DNA segment constituting the centromere. This unique make up might reflect some physical parameter, like curvature, of the DNA present in the centromere constriction. It is further proposed that a proteinaceous factor, centromerase, is responsible for holding the centromeres as one unit until meta-anaphase.
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Affiliation(s)
- B K Vig
- Department of Biology, University of Nevada, Reno 89557-0015
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15
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Abstract
During the past year important progress has been made in refining our understanding of how chromosomes become equally distributed to daughter cells during mitosis. Unlike the situation in diatoms and yeast, it now appears that spindle pole (centrosome) separation during spindle formation and anaphase B is mediated in vertebrates primarily by an astral pulling, and not a pushing, mechanism. Kinetochore motility is directionally unstable, which has important consequences for how chromosomes move to the equator of the forming spindle. Finally, the observation that sister chromatid disjunction occurs even in the presence of high levels of maturation promoting factor reveals that the series of biochemical events responsible for this phenomenon is not an obligatory part of the pathway by which the cell exits mitosis.
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Affiliation(s)
- J G Ault
- Wadsworth Center for Laboratories and Research, Albany, New York 12201-0509
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