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Veyrunes F, Watson J, Robinson TJ, Britton-Davidian J. Accumulation of rare sex chromosome rearrangements in the African pygmy mouse, Mus (Nannomys) minutoides: a whole-arm reciprocal translocation (WART) involving an X-autosome fusion. Chromosome Res 2007; 15:223-30. [PMID: 17285252 DOI: 10.1007/s10577-006-1116-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2006] [Revised: 11/28/2006] [Accepted: 11/28/2006] [Indexed: 01/05/2023]
Abstract
Although sex chromosomes are generally the most conserved elements of the mammalian karyotype, those of African pygmy mice show three extraordinary deviations from the norm: (a) asynaptic sex chromosomes, (b) multiple sex-autosome fusions, and (c) modifications of sex determination in some populations/species. In this study we identified, in two sex-reversed females of Mus (Nannomys) minutoides, a fourth rare sex chromosome change: a spontaneous whole-arm reciprocal translocation (WART) between an autosomal Robertsonian pair Rb(13.16) and the sex-autosome fusion Rb(X.1). This represents one of the very few reported cases of WARTs in natura within mammals, and is the first one to involve sex chromosomes. Hence, this finding offers new insights into the mechanisms of chromosomal differentiation in African pygmy mice, as WARTs may have contributed to the extensive diversity not only of autosomal Robertsonian fusions, but also of sex-autosome translocations. More widely, these results provide additional support to previous studies on the house mouse and the common shrew which indirectly inferred the role of WARTs in their karyotypic evolution, and may even help to understand how the fascinating 10 sex chromosome chain of the platypus might have evolved. This accumulation of rare sex chromosome changes in single specimens is, to our knowledge, exceptional among mammals.
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Affiliation(s)
- Frédéric Veyrunes
- Institut des Sciences de l'Evolution (UMR5554), Génétique & Environnement, Université Montpellier II, Montpellier, France.
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52
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Gilbert C, O'Brien PC, Bronner G, Yang F, Hassanin A, Ferguson-Smith MA, Robinson TJ. Chromosome painting and molecular dating indicate a low rate of chromosomal evolution in golden moles (Mammalia, Chrysochloridae). Chromosome Res 2007; 14:793-803. [PMID: 17180635 DOI: 10.1007/s10577-006-1091-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2006] [Revised: 09/18/2006] [Accepted: 09/18/2006] [Indexed: 10/23/2022]
Abstract
Golden moles (Chrysochloridae) are poorly known subterranean mammals endemic to Southern Africa that are part of the superordinal clade Afrotheria. Using G-banding and chromosome painting we provide a comprehensive comparison of the karyotypes of five species representing five of the nine recognized genera: Amblysomus hottentotus, Chrysochloris asiatica, Chrysospalax trevelyani, Cryptochloris zyli and Eremitalpa granti. The species are karyotypically highly conserved. In total, only four changes were detected among them. Eremitalpa granti has the most derived karyotype with 2n = 26 and differs from the remaining species (all of whom have 2n = 30) by one centric and one telomere:telomere fusion. In addition, two intrachromosomal rearrangements were detected in A. hottentotus. The painting probes also suggest the presence of a unique satellite DNA family located on chromosomes 11 and 12 of both C. asiatica and C. zyli. This represents a synapomorphy linking these two sympatric species as sister taxa. A molecular clock was calibrated adopting a relaxed Bayesian approach for multigene data sets comprising publicly available sequences derived from five gene fragments representative of three golden moles and 39 other eutherian species. The data suggest that golden moles diverged from a common ancestor approximately 28.5 mya (95% credibility interval = 21.5-36.5 mya). Based on an inferred chrysochlorid ancestral karyotype of 2n = 30, the estimated rate of 0.7 rearrangements per 10 my (95% Credibility Interval = 0.54-0.93) differs from the 'default rate' of mammalian chromosomal evolution which has been estimated at one change per 10 million years, thus placing the Chrysochloridae among the slower-evolving chromosomal lineages thus far recorded.
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Affiliation(s)
- C Gilbert
- Evolutionary Genomics Group, Department of Botany and Zoology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa
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53
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Ortiz MI, Pinna-Senn E, Rosa C, Lisanti JA. Localization of Telomeric Sequences in the Chromosomes of Three Species of Calomys (Rodentia, Sigmodontinae). CYTOLOGIA 2007. [DOI: 10.1508/cytologia.72.165] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- María Isabel Ortiz
- Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Argentina
| | - Elsa Pinna-Senn
- Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Argentina
| | - Carolina Rosa
- Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Argentina
| | - José Antonio Lisanti
- Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Argentina
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54
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Ventura K, Silva MJJ, Fagundes V, Christoff AU, Yonenaga-Yassuda Y. Non-telomeric sites as evidence of chromosomal rearrangement and repetitive (TTAGGG)n arrays in heterochromatic and euchromatic regions in four species of Akodon (Rodentia, Muridae). Cytogenet Genome Res 2006; 115:169-75. [PMID: 17065799 DOI: 10.1159/000095238] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2006] [Accepted: 03/17/2006] [Indexed: 11/19/2022] Open
Abstract
Comparative studies among four species--Akodonazarae (2n = 38), A. lindberghi (2n = 42), A. paranaensis (2n = 44) and A. serrensis (2n = 46)--employing classic cytogenetics (C- and G-bands) and fluorescence in situ hybridization with telomeric (TTAGGG)n sequencesare reported here. Non-telomeric signals in addition to the regular telomeric sites were detected in three species:A. azarae, A. lindberghi and A. serrensis. One interstitial telomeric site (ITS) was observed proximally at the long arm of chromosome 1 of A. azarae. The comparison of G-banding patterns among the species indicated that the ITS was due to a tandem fusion/fission rearrangement. Non-telomeric signals of A. lindberghi and A. serrensis were not related to chromosomal rearrangements; instead, the sequences co-localized with (i) heterochromatic regions of all chromosomes in A. serrensis; (ii) some heterochromatic regions in A. lindberghi, and (iii) both euchromatic and heterochromatic regions in the metacentric pair of A. lindberghi. These exceptional findings revealed that ITS in Akodon can be related to chromosomal rearrangements and repetitive sequences in the constitutive heterochromatin and that the richness of TTAGGG-like sequences in the euchromatin could be hypothesized to be a result of amplification of the referred sequence along the chromosome arms.
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Affiliation(s)
- K Ventura
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo Laboratório de Genética, São Paulo, Brazil.
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55
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Castiglia R, Garagna S, Merico V, Oguge N, Corti M. Cytogenetics of a new cytotype of African Mus (subgenus Nannomys) minutoides (Rodentia, Muridae) from Kenya: C- and G- banding and distribution of (TTAGGG)n telomeric sequences. Chromosome Res 2006; 14:587-94. [PMID: 16823620 DOI: 10.1007/s10577-006-1054-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2006] [Revised: 03/23/2006] [Accepted: 03/23/2006] [Indexed: 12/01/2022]
Abstract
We present the results of a cytogenetic study on Mus (Nannomys) minutoides from Kenya by means of C- and G- banding and in-situ fluorescence hybridization (FISH) to localize the telomeric sequences. The karyotype is characterized by the occurrence of several Rb chromosomes Rb(1.X), Rb(1.Y). Rb(2.17), Rb(3.13), Rb(4.10), Rb(5.11), Rb(6.7), Rb(8.12), not previously described for this species. This finding suggests a high level of chromosomal diversification, which means it is possible to consider this cytotype as a new, well-differentiated, chromosomal lineage within the subgenus. The C-banding of the metaphases illustrated conspicuous blocks of centromeric heterochromatin at the paracentromeric regions of all telocentric chromosomes. Centromeric heterochromatin is not visible on all biarmed chromosomes. Following hybridization with telomeric probes, bright interstitial telomeric sequence (ITS) fluorescence signals are evident at the pericentromeric area of all Rb chromosomes, with the exception of Rb(2.17). Considering the localization of the C-positive heterochromatin and of the telomeric sequences, the events leading to the Kenyan cytotype from an all-telocentric condition probably included two steps: first, fusion without loss of heterochromatin and pericentromeric telomeric sequences; second, the reduction of the C-positive satellite DNA followed by the amplification of telomeric sequences in the C-negative paracentromeric region of Rb chromosomes. The presence of a single Rb(2.17) without ITS indicates possible variations of this mechanism.
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Affiliation(s)
- Riccardo Castiglia
- Dipartimento di Biologia Animale e dell'Uomo, Università di Roma La Sapienza, via A. Borelli 50, 00161, Roma, Italy.
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Kalitsis P, Griffiths B, Choo KHA. Mouse telocentric sequences reveal a high rate of homogenization and possible role in Robertsonian translocation. Proc Natl Acad Sci U S A 2006; 103:8786-91. [PMID: 16731628 PMCID: PMC1482656 DOI: 10.1073/pnas.0600250103] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The telomere and centromere are two specialized structures of eukaryotic chromosomes that are essential for chromosome stability and segregation. These structures are usually characterized by large tracts of tandemly repeated DNA. In mouse, the two structures are often located in close proximity to form telocentric chromosomes. To date, no detailed sequence information is available across the mouse telocentric regions. The antagonistic mechanisms for the stable maintenance of the mouse telocentric karyotype and the occurrence of whole-arm Robertsonian translocations remain enigmatic. We have identified large-insert fosmid clones that span the telomere and centromere of several mouse chromosome ends. Sequence analysis shows that the distance between the telomeric T2AG3 and centromeric minor satellite repeats range from 1.8 to 11 kb. The telocentric regions of different mouse chromosomes comprise a contiguous linear order of T2AG3 repeats, a highly conserved truncated long interspersed nucleotide element 1 repeat, and varying amounts of a recently discovered telocentric tandem repeat that shares considerable identity with, and is inverted relative to, the centromeric minor satellite DNA. The telocentric domain as a whole exhibits the same polarity and a high sequence identity of >99% between nonhomologous chromosomes. This organization reflects a mechanism of frequent recombinational exchange between nonhomologous chromosomes that should promote the stable evolutionary maintenance of a telocentric karyotype. It also provides a possible mechanism for occasional inverted mispairing and recombination between the oppositely oriented TLC and minor satellite repeats to result in Robertsonian translocations.
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Affiliation(s)
- Paul Kalitsis
- *Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Victoria 3052, Australia; and
- Department of Pediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Victoria 3052, Australia
- To whom correspondence may be addressed. E-mail:
or
| | - Belinda Griffiths
- *Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Victoria 3052, Australia; and
- Department of Pediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Victoria 3052, Australia
| | - K. H. Andy Choo
- *Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Victoria 3052, Australia; and
- Department of Pediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Victoria 3052, Australia
- To whom correspondence may be addressed. E-mail:
or
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57
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Camats N, Ruiz-Herrera A, Parrilla JJ, Acien M, Payá P, Giulotto E, Egozcue J, García F, Garcia M. Genomic instability in rat: breakpoints induced by ionising radiation and interstitial telomeric-like sequences. Mutat Res 2006; 595:156-66. [PMID: 16413932 DOI: 10.1016/j.mrfmmm.2005.11.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2005] [Revised: 10/27/2005] [Accepted: 11/18/2005] [Indexed: 11/16/2022]
Abstract
The Norwegian rat (Rattus norvegicus) is the most widely studied experimental species in biomedical research although little is known about its chromosomal structure. The characterisation of possible unstable regions of the karyotype of this species would contribute to the better understanding of its genomic architecture. The cytogenetic effects of ionising radiation have been widely used for the study of genomic instability, and the importance of interstitial telomeric-like sequences (ITSs) in instability of the genome has also been reported in previous studies in vertebrates. In order to describe the unstable chromosomal regions of R. norvegicus, the distribution of breakpoints induced by X-irradiation and ITSs in its karyotype were analysed in this work. For the X-irradiation analysis, 52 foetuses (from 14 irradiated rats) were studied, 4803 metaphases were analysed, and a total of 456 breakpoints induced by X-rays were detected, located in 114 chromosomal bands, with 25 of them significantly affected by X-irradiation (hot spots). For the analysis of ITSs, three foetuses (from three rats) were studied, 305 metaphases were analysed and 121 ITSs were detected, widely distributed in the karyotype of this species. Seventy-six percent of all hot spots analysed in this study were co-localised with ITSs.
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Affiliation(s)
- Núiria Camats
- Institut de Biotecnologia i Biomedicina, Universitat Autònoma de Barcelona, 08193 Barcelona, Spain
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58
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Bolzán AD, Bianchi MS. Telomeres, interstitial telomeric repeat sequences, and chromosomal aberrations. Mutat Res 2006; 612:189-214. [PMID: 16490380 DOI: 10.1016/j.mrrev.2005.12.003] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2005] [Revised: 12/29/2005] [Accepted: 12/30/2005] [Indexed: 11/18/2022]
Abstract
Telomeres are specialized nucleoproteic complexes localized at the physical ends of linear eukaryotic chromosomes that maintain their stability and integrity. The DNA component of telomeres is characterized by being a G-rich double stranded DNA composed by short fragments tandemly repeated with different sequences depending on the species considered. At the chromosome level, telomeres or, more properly, telomeric repeats--the DNA component of telomeres--can be detected either by using the fluorescence in situ hybridization (FISH) technique with a DNA or a peptide nucleic acid (PNA) (pan)telomeric probe, i.e., which identifies simultaneously all of the telomeres in a metaphase cell, or by the primed in situ labeling (PRINS) reaction using an oligonucleotide primer complementary to the telomeric DNA repeated sequence. Using these techniques, incomplete chromosome elements, acentric fragments, amplification and translocation of telomeric repeat sequences, telomeric associations and telomeric fusions can be identified. In addition, chromosome orientation (CO)-FISH allows to discriminate between the different types of telomeric fusions, namely telomere-telomere and telomere-DNA double strand break fusions and to detect recombination events at the telomere, i.e., telomeric sister-chromatid exchanges (T-SCE). In this review, we summarize our current knowledge of chromosomal aberrations involving telomeres and interstitial telomeric repeat sequences and their induction by physical and chemical mutagens. Since all of the studies on the induction of these types of aberrations were conducted in mammalian cells, the review will be focused on the chromosomal aberrations involving the TTAGGG sequence, i.e., the telomeric repeat sequence that "caps" the chromosomes of all vertebrate species.
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Affiliation(s)
- Alejandro D Bolzán
- Laboratorio de Citogenética y Mutagénesis, Instituto Multidisciplinario de Biología Celular (IMBICE), C.C. 403, 1900 La Plata, Argentina.
| | - Martha S Bianchi
- Laboratorio de Citogenética y Mutagénesis, Instituto Multidisciplinario de Biología Celular (IMBICE), C.C. 403, 1900 La Plata, Argentina
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59
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PASCOE PL. Chromosomal polymorphism in the Atlantic dog-whelk, Nucella lapillus (Gastropoda: Muricidae): nomenclature, variation and biogeography. Biol J Linn Soc Lond 2006. [DOI: 10.1111/j.1095-8312.2006.00567.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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60
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Ivanitskaya E, Belyayev A, Nevo E. Heterochromatin differentiation shows the pathways of karyotypic evolution in Israeli mole rats (Spalax, Spalacidae, Rodentia). Cytogenet Genome Res 2006; 111:159-65. [PMID: 16103658 DOI: 10.1159/000086386] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2004] [Accepted: 11/25/2004] [Indexed: 11/19/2022] Open
Abstract
C-banding, base-specific fluorochrome staining (CMA3/DA/DAPI), and comparative genomic hybridization (CGH) were used to analyze the constitutive heterochromatin in two Israeli Spalax species, S. galili (2n = 52) and S. judai (2n = 60). It was shown that C-positive centromeric heterochromatin and some telomeric sites comprise GC-rich DNA sequences in both species. Comparative genomic in situ hybridization revealed slight qualitative differences in highly repetitive sequences in the two Spalax species. Eight acrocentric pairs in S. judai that are involved in Robertsonian rearrangements, possessed composite heterochromatin with a preference of S. judai highly repetitive sequences in the proximal region. Heterochromatin of the sex chromosomes, two biarmed homologous pairs (4 and 5) in both species, and acrocentric chromosomes from the group with a variable centromere position in S. judai was entirely species-specific. The high level of homology in the composition of heterochromatin may relate to the recent divergence of Israeli Spalax. Interspecies heterochromatin differences are discussed in the context of possible mechanisms in the Spalax chromosome evolution.
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Affiliation(s)
- E Ivanitskaya
- Institute of Evolution, University of Haifa, Haifa, Israel.
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61
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Rossi AR, Gornung E, Sola L, Nirchio M. Comparative molecular cytogenetic analysis of two congeneric species, Mugil curema and M. liza (Pisces, Mugiliformes), characterized by significant karyotype diversity. Genetica 2005; 125:27-32. [PMID: 16175452 DOI: 10.1007/s10709-005-2668-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2004] [Accepted: 02/04/2005] [Indexed: 11/30/2022]
Abstract
Two congeneric mullet species, Mugil liza and M. curema, respectively with an all-uniarmed and an all-biarmed karyotype, were cytogenetically studied by base-specific fluorochrome staining and FISH-mapping of 45S and 5S ribosomal RNA genes (rDNA) and the (TTAGGG)(n) telomeric repeats. Whereas 45S rDNA sites might be homeologus in the two species, 5S rDNA sites are not, as they are localized on chromosome arms of different size. In both species, the (TTAGGG)(n) telomeric probe hybridized to natural telomeres and was found scattered along the NORs. In metacentric chromosomes of M. curema, no pericentromeric signals of the telomeric probe were detected. Data are discussed in relation to the karyotype evolution in Mugilidae and to the mechanisms and the evolutionary implications of Robertsonian rearrangements in M. curema.
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Affiliation(s)
- A R Rossi
- Department of Animal and Human Biology, University of Rome I "La Sapienza", via A. Borelli 50, 00161 Rome, Italy
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62
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Zhdanova NS, Karamisheva TV, Minina J, Astakhova NM, Lansdorp P, Kammori M, Rubtsov NB, Searle JB. Unusual distribution pattern of telomeric repeats in the shrews Sorex araneus and Sorex granarius. Chromosome Res 2005; 13:617-25. [PMID: 16170626 DOI: 10.1007/s10577-005-0988-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2005] [Accepted: 06/15/2005] [Indexed: 11/30/2022]
Abstract
Sorex araneus and Sorex granarius are sibling species within the Sorex araneus group with karyotypes composed of almost identical chromosome arms. S. granarius has a largely acrocentric karyotype, while, in S. araneus, various of these acrocentrics have combined together by Robertsonian (Rb) fusions to form metacentrics, with the numbers and types of metacentrics differing between chromosomal races. Our studies on telomeric sequences in S. araneus and S. granarius revealed differences between chromosomes and between species. In S. araneus (the Novosibirsk race), hybridization signals were present on the telomeres of all the chromosomes after FISH with a PCR-generated telomeric probe. In addition, hybridization signals were observed at high frequencies in the pericentric regions of some but not all metacentrics formed by Rb fusion. There were fewer signals on those metacentrics formed earlier in the evolution of S. araneus. This suggests that S. araneus chromosomes retain at least some telomeric repeats during Rb fusion, but that these repeats are lost or modified over time. These results are critical for the interpretation of the well-studied hybrid zones between chromosomal races of S. araneus, given that Rb fission has been postulated in such hybrid zones and that the likelihood of Rb fission will relate to presence/absence of telomeric sequences at the centromeres of metacentrics. In S. granarius, there were strong signals at the proximal (centromeric) telomeres of the acrocentrics after FISH with a DNA telomeric probe. FISH with a PNA telomeric probe on S. granarius acrocentrics showed that the proximal telomeres were 213 kb on average, while the length of the distal telomeres was 3.8 kb on average. Two-colour FISH, using a telomeric DNA probe and a microdissected probe generated from the pericentric regions of the S. granarius chromosomes a and b, revealed regions on distinct chromatin fibres where telomeric and microdissected probes were colocalized or localized sequentially. The proximal telomeres of S. granarius are highly unusual both in their large size and their heterogeneous structure relative to the telomeres of other mammals.
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Affiliation(s)
- Natalia S Zhdanova
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
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63
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Tryfonopoulos G, Chondropoulos B, Fraguedakis-Tsolis S. Allozymic polymorphism among 14 populations of the house mouse, Mus musculus domesticus, from Greece. Biochem Genet 2005; 43:11-24. [PMID: 15859516 DOI: 10.1007/s10528-005-1063-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Nineteen loci from 239 individuals of the house mouse Mus musculus domesticus (Rodentia, Muridae) were analyzed by means of thin layer electrophoresis. The mice were collected from 14 localities of Greece mainly confined to the area of NW Peloponnese, where a Robertsonian (Rb) system is observed. The individuals were chromosomally characterized by nine diploid numbers, the 2n = 24, 26, 27, 28, 29, 30, 31, 32, and 40. The statistic elaboration revealed that all 14 populations studied were not characterized by cohesive demic structure and high inbreed levels while the gene flow among them has resulted in low levels of genetic differentiation. The resulting values for Nei's genetic distance corresponded to distances known for the level of geographical populations of M. musculus. Wagner's cladogram for the phylogenetic relations between the populations studied implied that it is the diploid number, rather than the geographical factor, that characterizes or dominates each population, which mainly influences the phylogenetic relationships.
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Affiliation(s)
- Georgios Tryfonopoulos
- Laboratory of Zoology, Section of Animal Biology, Department of Biology, University of Patra, GR-26001 Patra, Greece.
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64
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Colangelo P, Corti M, Verheyen E, Annesi F, Oguge N, Makundi RH, Verheyen W. Mitochondrial phylogeny reveals differential modes of chromosomal evolution in the genus Tatera (Rodentia: Gerbillinae) in Africa. Mol Phylogenet Evol 2005; 35:556-68. [PMID: 15878125 DOI: 10.1016/j.ympev.2005.02.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2004] [Revised: 02/16/2005] [Accepted: 02/18/2005] [Indexed: 10/25/2022]
Abstract
The African gerbils of the genus Tatera are widespread and abundant throughout sub-Saharan Africa. There is still today a certain controversy concerning the taxonomy of these rodents and very few attempts have been made to assess their systematic relationships. The present paper introduces findings based on the partial sequences of cytochrome b (495 bp) and the 16S rRNA (469 bp) mitochondrial genes of six (T. robusta, T. nigricauda, T. vicina, T. leucogaster, T. valida, and T. kempi) species together with two additional taxa. We also report the karyotypes of T. vicina and T. leucogaster. We propose that T. vicina should be considered as a valid species and show the monophyly of the robusta species group, with the exclusion of T. leucogaster. Our results show there is a different chromosomal evolutionary pattern within the two major lineages, which is recognizable through molecular phylogenetics. One is characterized by karyotype stability and the other by a considerable number of chromosomal rearrangements. The lineage divergence coincides with the formation of the East African Rift. The processes that led to the origin of the East African species seem to be related to the subsequent climatic changes, which caused cyclic contraction and expansion of the savannah biomes. Furthermore, geological activities that characterized East Africa during Plio-Pleistocene may also have contributed to lineage divergence.
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Affiliation(s)
- Paolo Colangelo
- Dipartimento di Biologia Animale e dell'Uomo, Università di Roma La Sapienza, Via Borelli 50, 00161 Roma, Italy.
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65
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TRYFONOPOULOS GEORGEA, CHONDROPOULOS BASILP, FRAGUEDAKIS-TSOLIS STELLAE. Mitochondrial DNA polymorphisms of the house mouse Mus musculus domesticus from Greece, focusing on the Robertsonian chromosomal system of north-west Peloponnese. Biol J Linn Soc Lond 2005. [DOI: 10.1111/j.1095-8312.2005.00461.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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66
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67
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Lanneluc I, Desmarais E, Boursot P, Dod B, Bonhomme F. Characterization of a centromeric marker on mouse Chromosome 11 and its introgression in a domesticus/musculus hybrid zone. Mamm Genome 2004; 15:924-34. [PMID: 15672596 DOI: 10.1007/s00335-004-2397-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
It has been proposed that the distribution of Robertsonian chromosome fusions and the Chromosome 11 Nucleolar Organizer Region (NOR) in the Danish hybrid zone between M. m. musculus and M. m. domesticus stems from centromeric incompatibilities between the two subspecies. To test this hypothesis, we identified and characterized a diagnostic subspecific marker closely linked to the centromere on mouse Chromosome 11. Using an allele-specific PCR assay, we investigated the introgression pattern of this centromere in a large sample of mice from a North-South transect of the hybrid zone in Jutland. Domesticus alleles were found to introgress far away from the center of the zone on the musculus side. These results suggest there is no incompatibility between the domesticus centromere of Chromosome 11 in the musculus genomic background.
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Affiliation(s)
- Isabelle Lanneluc
- Laboratoire Genome Populations Interactions Adaptation (UMR 5171 CNRS-UM2-IFREMER), Université de Montpellier II C.C. 63, Place E. Bataillon, 34095 Montpellier 5, France
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68
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Zeng K, de las Heras JI, Ross A, Yang J, Cooke H, Shen MH. Localisation of centromeric proteins to a fraction of mouse minor satellite DNA on a mini-chromosome in human, mouse and chicken cells. Chromosoma 2004; 113:84-91. [PMID: 15300445 DOI: 10.1007/s00412-004-0299-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2004] [Revised: 06/08/2004] [Accepted: 06/09/2004] [Indexed: 11/25/2022]
Abstract
Centromeres are required for faithful segregation of chromosomes in cell division. It is not clear how centromere sites are specified on chromosomes in vertebrates. We have previously introduced a mini-chromosome, named ST1, into a variety of cell lines including human HT1080, mouse LA9 and chicken DT40. This mini-chromosome, segregating faithfully in these cells, contains mouse minor and major, and human Y alpha-satellite DNA repeats. In this study, after determining the organisation of the satellite repeats, we investigated the location of the centromere on the mini-chromosome by combined immunocytochemistry and fluorescence in situ hybridisation analysis. Centromeric proteins were consistently co-localised with the minor satellite repeats in all three cell lines. When chromatin fibres were highly stretched, centromeric proteins were only seen on a small portion of the minor satellite repeats. These results indicate that a fraction of the minor satellite repeats is competent in centromere function not only in mouse but also in human and chicken cells.
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Affiliation(s)
- Kang Zeng
- MRC Human Genetics Unit, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK
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69
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70
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Arenas C, Escudero T, Mestres F, Coll MD, Cuadras CM. CACROMOS: A Computer Program to Reconstruct the Position of Chromosomes on the Metaphase Plate. Hereditas 2004. [DOI: 10.1111/j.1601-5223.2000.00157.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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71
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Rebuzzini P, Lisa A, Giulotto E, Mondello C. Chromosomal end-to-end fusions in immortalized mouse embryonic fibroblasts deficient in the DNA-dependent protein kinase catalytic subunit. Cancer Lett 2004; 203:79-86. [PMID: 14670620 DOI: 10.1016/j.canlet.2003.08.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Telomeres constitute the ends of the linear eukaryotic chromosomes and are essential for the maintenance of chromosome stability and genome integrity. One of the consequences of an altered telomere structure is the formation of telomeric fusions (TFs), that is aberrant chromosomes in which two elements are fused at their telomeres. Proteins involved in the non-homologous end joining pathway for the repair of the DNA double strand breaks, as the DNA-dependent protein kinase catalytic subunit (DNA-PKcs), contribute to the formation of a functional telomere. To investigate the role of DNA-PKcs in telomere functionality, we studied the frequency of TFs in mouse embryonic fibroblasts obtained from animals in which the DNA-PKcs gene had been inactivated; the analysis was performed prior and after spontaneous immortalization in culture. Our results suggest that DNA-PKcs deficiency has a limited effect, if any, on TF formation in primary cells, while it further increases chromosomal instability in immortalized cells. In fact, the frequency of TFs was significantly higher in immortalized DNA-PKcs mutant cells compared to wild type cells. Together with TFs, we also found metacentric or submetacentric chromosomes in which no telomeric sequences were detected at the joining site. The frequency of this anomaly, that resembles the Robertsonian translocations observed in wild mice, was independent of the DNA-PKcs genotype. This suggests that the formation of these rearranged chromosomes does not rely on a functional DNA-PKcs.
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Affiliation(s)
- Paola Rebuzzini
- Istituto di Genetica Molecolare, CNR, Via Abbiategrasso 207, 27100 Pavia, Italy
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72
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Traut W, Endl E, Garagna S, Scholzen T, Schwinger E, Gerdes J, Winking H. Chromatin preferences of the perichromosomal layer constituent pKi-67. Chromosome Res 2003; 10:685-94. [PMID: 12575796 DOI: 10.1023/a:1021532914023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The proliferation-associated nuclear protein pKi-67 relocates from the nucleolus to the chromosome surface during the G2/M transition of the cell cycle and contributes to the formation of the 'perichromosomal layer'. We investigated the in-vivo binding preferences of pKi-67 for various chromatin blocks of the mitotic chromosomes from the human and two mouse species, Mus musculus and M. caroli. All chromosomes were decorated with pKi-67 but displayed a gap of pKi-67 decoration in the centromere and NOR regions. pKi-67 distribution in a rearranged mouse chromosome showed that the formation of the centromeric gap was controlled by the specific chromatin in that region. While most chromatin served as a substrate for direct or indirect binding of pKi-67, we identified three types of chromatin that bound less or no pKi-67. These were: (1) the centromeric heterochromatin defined by the alpha satellite DNA in the human, by the mouse minor satellite in M. musculus and the 60- and 79-bp satellites in M. caroli; (2) the pericentromeric heterochromatin in M. musculus defined by the mouse major satellite, and (3) NORs in the human and in M. musculus defined by rDNA repeats. In contrast, the conspicuous blocks of pericentromeric heterochromatin in human chromosomes 1, 9 and 16 containing the 5-bp satellite showed intense pKi-67 decoration. The centromeric gap may have a biological significance for the proper attachment of the chromosomes to the mitotic spindle. In this context, our results suggest a new role for centromeric heterochromatin: the control of the centromeric gap in the perichromosomal layer.
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Affiliation(s)
- Walther Traut
- Institut für Biologie, Universität Lübeck, D-23538 Lübeck, Germany.
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73
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Canapa A, Cerioni PN, Barucca M, Olmo E, Caputo V. A centromeric satellite DNA may be involved in heterochromatin compactness in gobiid fishes. Chromosome Res 2003; 10:297-304. [PMID: 12199143 DOI: 10.1023/a:1016519708187] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Centromere and telomere composition and organization were studied in various gobiid species exhibiting and not exhibiting chromosome polymorphisms involving Robertsonian rearrangements. In Gobius cobitis, we isolated an AT-rich centromeric DNA satellite, designated pCOB, and found that several sequences contain adenine stretches, various CA/TG dinucleotide steps, and a sequence 76% homologous to the yeast CDE III centromeric sequence. All of these traits are generally considered important for centromeric function, and the hypothesis has been advanced that some are involved in the control of DNA curvature and thus in the degree of centromeric chromatin compactness. Based on these features, and on the fact that they are found only in the species not exhibiting Robertsonian biarmed chromosomes, a role for pCOB in preventing centric fusions has been hypothesized. Our data also suggest that, as in other species, the formation of Robertsonian biarmed chromosomes is accompanied by the loss of telomeric sequences.
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Affiliation(s)
- Adriana Canapa
- Institute of Biology and Genetics, Faculty of Sciences, University of Ancona, via Brecce Bianche, Ancona, Italy
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74
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Castiglia R, Gornung E, Corti M. Cytogenetic analyses of chromosomal rearrangements in Mus minutoides/musculoides from North-West Zambia through mapping of the telomeric sequence (TTAGGG)n and banding techniques. Chromosome Res 2003; 10:399-406. [PMID: 12296522 DOI: 10.1023/a:1016853719616] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Three specimens of M. minutoides/musculoides from Zambia were cytogenetically studied through G- and C-banding, DAPI staining and fluorescence in-situ hybridization (FISH) with a (TTAGGG)n telomeric sequence. Biarmed chromosomes were identified according to the current nomenclature as follows: Rb(2.7), Rb(3.12), Rb(4.5), Rb(6.8), Rb(9.16), and the sex chromosomes Rb(1.X), Rb(1.Y) and Rb(1.Xd), originated from the deleted X chromosome. One female showed the diploid number 2n = 24; in the two other individuals, the Rb(9.16) occurred in a heteromorphic condition, and, accordingly, the diploid number was 2n = 25. FISH showed the sites of telomeric sequences at telomeres of all the chromosomes, and in an interstitial position at the centromeres of all Robertsonian metacentrics, except one - the Rb(6.8), though the patterns of hybridization varied between chromosomes. Sex chromosome pairs, in the male and females, showed a similar C-banding pattern, but revealed clear differences after FISH. Traces of telomeric sequences were found dispersed in the whole-heterochromatic arm of the Rb(1.Xd). No visible bond between C-positive heterochromatin and telomeric sequences were detected in the other either bi- or uniarmed chromosomes, indicating that they may actually represent retained telomeres in the Robertsonian metacentrics.
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Affiliation(s)
- Riccardo Castiglia
- Department of Animal and Human Biology, University of Rome La Sapienza, Italy.
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75
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Dumas D, Britton-Davidian J. Chromosomal rearrangements and evolution of recombination: comparison of chiasma distribution patterns in standard and robertsonian populations of the house mouse. Genetics 2002; 162:1355-66. [PMID: 12454079 PMCID: PMC1462339 DOI: 10.1093/genetics/162.3.1355] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The effects of chromosomal rearrangements on recombination rates were tested by the analysis of chiasma distribution patterns in wild house mice. Males and females of two chromosomal races from Tunisia differing by nine pairs of Robertsonian (Rb) fusions (standard all-acrocentric, 2N = 40 and 2N = 22) were studied. A significant decrease in chiasma number (CN) was observed in Rb mice compared to standard ones for both sexes. The difference in CN was due to a reduction in the number of proximal chiasmata and was associated with an overall more distal redistribution. These features were related to distance of chiasmata to the centromere, suggesting that the centromere effect was more pronounced in Rb fusions than in acrocentric chromosomes. These modifications were interpreted in terms of structural meiotic constraints, although genic factors were likely involved in patterning the observed differences between sexes within races. Thus, the change in chromosomal structure in Rb mice was associated with a generalized decrease in recombination due to a reduction in diploid number, a lower CN, and a decrease in the efficiency of recombination. The effects of such modifications on patterns of genic diversity are discussed in the light of models of evolution of recombination.
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Affiliation(s)
- David Dumas
- Laboratoire Génétique et Environnement, Institut des Sciences de l'Evolution (UMR 5554), Université Montpellier II, cc 065, 34095 Montpellier Cedex 5, France.
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76
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Faria KDC, Morielle-Versute E. In situ hybridization of bat chromosomes with human (TTAGGG)n probe, after previous digestion with Alu I. Genet Mol Biol 2002. [DOI: 10.1590/s1415-47572002000400003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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77
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Hemann MT, Strong MA, Hao LY, Greider CW. The shortest telomere, not average telomere length, is critical for cell viability and chromosome stability. Cell 2001; 107:67-77. [PMID: 11595186 DOI: 10.1016/s0092-8674(01)00504-9] [Citation(s) in RCA: 843] [Impact Index Per Article: 36.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Loss of telomere function can induce cell cycle arrest and apoptosis. To investigate the processes that trigger cellular responses to telomere dysfunction, we crossed mTR-/- G6 mice that have short telomeres with mice heterozygous for telomerase (mTR+/-) that have long telomeres. The phenotype of the telomerase null offspring was similar to that of the late generation parent, although only half of the chromosomes were short. Strikingly, spectral karyotyping (SKY) analysis revealed that loss of telomere function occurred preferentially on chromosomes with critically short telomeres. Our data indicate that, while average telomere length is measured in most studies, it is not the average but rather the shortest telomeres that constitute telomere dysfunction and limit cellular survival in the absence of telomerase.
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Affiliation(s)
- M T Hemann
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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78
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Piálek J, Hauffe HC, Rodríguez-Clark KM, Searle JB. Raciation and speciation in house mice from the Alps: the role of chromosomes. Mol Ecol 2001; 10:613-25. [PMID: 11298973 DOI: 10.1046/j.1365-294x.2001.01209.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
There are at least 24 different karyotypic races of house mouse in the central Alps, each characterized by a different complement of ancestral acrocentric and derived metacentric chromosomes; altogether 55 different metacentric chromosomes have been described from the region. We argue that this chromosome variation largely arose in situ. If these races were to make contact, in most cases they would produce F1 hybrids with substantial infertility (sometimes complete sterility), due to nondisjunction and germ cell death associated with the formation of long-chain and/or ring configurations at meiosis. We present fertility estimates to confirm this for two particular hybrid types, one of which demonstrates male-limited sterility (in accordance with Haldane's Rule). As well as a model for speciation in allopatry, the Alpine mouse populations are of interest with regards speciation in parapatry: we discuss a possible reinforcement event. Raciation of house mice appears to have happened on numerous occasions within the central Alps. To investigate one possible source of new karyotypic races, we use a two-dimensional stepping stone model to examine the generation of recombinant races within chromosomal hybrid zones. Using field-derived ecological data and laboratory-derived fertility estimates, we show that hybrid karyotypic races can be generated at a reasonable frequency in simulations. Our model complements others developed for flowering plants that also emphasize the potential of chromosomal hybrid zones in generating new stable karyotypic forms.
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Affiliation(s)
- J Piálek
- Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, CZ-675 02 Studenec 122, Czech Republic
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79
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Catalan J, Auffray JC, Pellestor F, Britton-Davidian J. Spontaneous occurrence of a Robertsonian fusion involving chromosome 19 by single whole-arm reciprocal translocation (WART) in wild-derived house mice. Chromosome Res 2001; 8:593-601. [PMID: 11117355 DOI: 10.1023/a:1009281823488] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Chromosomal races of the house mouse (Mus musculus domesticus) bear Robertsonian (Rb) fusions, which consist of centric translocations between two non-homologous acrocentric chromosomes. The high level of diversity of these fusions in house mice is generated by de-novo formation of Rb fusions and subsequent whole-arm reciprocal exchanges (WARTs). This paper describes the spontaneous occurrence of a new Rb fusion, Rb(4.19), in progeny of wild-derived house mice segregating for Rb(4.12). The chromosomal mutation was traced to a female which exhibited germline and somatic mosaicism indicating an early embryonic origin of the mutation. FISH analysis of centromerically-located ribosomal genes suggested that no modification was observed on chromosomes 12 and 19 prior to or following the occurrence of Rb(4.19). Distribution of telomeric sequences showed that both Rb fusions lacked telomeres in their centromeric regions. It is argued that this spontaneous mutation most likely originated by single whole-arm reciprocal translocation (WART) between Rb(4.12) and an acrocentric chromosome 19, resulting in Rb(4.19) and a neo-acrocentric chromosome 12. Sequences required for centromeric function and proximal telomeres would have been transferred to the neo-chromosome 12 from chromosome 19 during the translocation. The existence of such WARTs which generate derived acrocentric chromosomes has several implications for chromosomal evolution in house mice.
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Affiliation(s)
- J Catalan
- Institut des Sciences de l'Evolution, UMR 5554, Laboratoire Génétique et Environnement, Université Montpellier II, France.
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80
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Odierna G, Andreone F, Aprea G, Arribas O, Capriglione T, Vences M. Cytological and molecular analysis in the rare discoglossid species, Alytes muletensis (Sanchiz & Adrover 1977) and its bearing on archaeobatrachian phylogeny. Chromosome Res 2001; 8:435-42. [PMID: 10997783 DOI: 10.1023/a:1009266904940] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Cytogenetic and molecular data on Alytes muletensis (Amphibia: Discoglossidae) are compared with other representatives of archaeobatrachian frogs: Bombina variegata pachypus, Pelobates cultripes, Pelodytes punctatus, Xenopus laevis, and Discoglossus. A. muletensis has the karyotype typical for the genus Alytes, 38 elements with either one or two arms, some of which can be considered as 'microchromosomes'. The NORs are located on the telomeres of the tenth chromosome pair which agrees with the state in A. obstetricians but differs from A. cisternasii reflecting phylogenetic affinities. C-banding and staining with DAPI and chromomycin A3 revealed important blocks of telomeric CMA-positive heterochromatin on the smaller chromosomes of Alytes, similar to the state found in Discoglossus. Phylogenetic analysis of 750 bp of fragments of the mitochondrial 16S and 12S rRNA genes corroborated that Discoglossus and Alytes are sister taxa which together probably form the sister group of the Bombinatorinae. Centromeric heterochromatin in Alytes may be responsible for the retention of a plesiomorphic asymmetric karyotype which independently has evolved into a symmetric karyotype through centric fusions in Bombina and Discoglossus. The HindIII satellite DNA family was present in all archaeobatrachians studied but absent in hyloid and ranoid neobatrachians.
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Affiliation(s)
- G Odierna
- Dipartimento Biologia Evolutiva e Comparata, Università di Napoli Federico II, Italy
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81
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Finato AO, Varella-Garcia M, Tajara EH, Taddei VA, Morielle-Versute E. Intrachromosomal distribution of telomeric repeats in Eumops glaucinus and Euntops perotis (Molossidae, Chiroptera). Chromosome Res 2001; 8:563-9. [PMID: 11117352 DOI: 10.1023/a:1009288121670] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The location of chromosomal telomeric repeats (TTAGGG)n was investigated in two species of the Molossidae family, Eumops glaucinus and Eumops perotis. The diploid chromosome number (2n) is 40 in E. glaucinus and 48 in E. perotis and the fundamental numbers (FN) are 64 and 58, respectively. It has been suggested that the E. glaucinus karyotype has evolved from the E. perotis karyotype through Robertsonian fusion events. In the present study, the telomeric sequences were detected at the termini of chromosomes in both species. In addition, E. glaucinus also displayed telomeric repeats in centromeric and pericentromeric regions in almost all biarmed chromosomes. Conversely, in E. perotis pericentromeric signals were only observed in two biarmed chromosomes. In both E. glaucinus and E. perotis, such telomeric sequences were observed as part of the heterochromatin. The interstitial sites of telomeric sequences suggest that they are remnants of telomeres of ancestral chromosomes that participated in the fusion event.
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Affiliation(s)
- A O Finato
- Department of Genetics, IB- UNESP, Botucatu, SP, Brazil
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82
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Garagna S, Marziliano N, Zuccotti M, Searle JB, Capanna E, Redi CA. Pericentromeric organization at the fusion point of mouse Robertsonian translocation chromosomes. Proc Natl Acad Sci U S A 2001; 98:171-5. [PMID: 11136254 PMCID: PMC14563 DOI: 10.1073/pnas.98.1.171] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In mammals, Robertsonian (Rb) translocation (the joining of two telo/acrocentric chromosomes at their centromere to form a metacentric) is the most effective process in chromosomal evolution leading to speciation; its occurrence also affects human health (through the induction of trisomies) and the fertility of farm animals. To understand the mechanism of Rb translocation, we used the house mouse as a model system and studied the organization of pericentromeric satellite DNAs (satDNA) of telocentrics and Rb chromosomes, both minor and major satDNA. The chromosome-orientation fluorescence in situ hybridization (CO-FISH) technique was used to analyze the major satDNA. To detect the very small amount of minor satDNA, a procedure was developed that combines CO-FISH with primed in situ labeling and conventional FISH and is five times more sensitive than the CO-FISH procedure alone. It was found that both the major and the minor satDNA tandem repeats are oriented head-to-tail in telocentric and Rb chromosomes, and their polarity is always the same relative to the centromere. We suggest that all tandemly repetitive satDNAs in a species probably are locked into such a symmetry constraint as a universal consequence of chromosomal evolution. Rb translocation breakpoints were found localized within the minor satDNA of telocentrics, and these sequences contributed symmetrically to the formation of the centromeric region of the Rb chromosomes. These results are important for an understanding of the geometry of Rb translocations and suggest the study of DNA orientation as a new tool for investigating these rearrangements.
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Affiliation(s)
- S Garagna
- Dipartimento di Biologia Animale, Laboratorio di Biologia dello Sviluppo, Universita' degli Studi di Pavia, Piazza Botta 9, 27100 Pavia, Italy.
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83
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Silva MJ, Yonenaga-Yassuda Y. Autosomal and sex chromosomal polymorphisms with multiple rearrangements and a new karyotype in the genus Rhipidomys (Sigmodontinae, Rodentia). Hereditas 2000; 131:211-20. [PMID: 10783531 DOI: 10.1111/j.1601-5223.1999.00211.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Two diploid numbers and five karyomorphs were found in ten specimens of Rhipidomys (Sigmodontinae, Rodentia) from three states in Brazil: 2n = 50 from Amazonas, and 2n = 44 from Mato Grosso and Bahia. CBG, GTG, and RBG-banding and Ag-NOR analyses were performed, as well as fluorescence in situ: hybridization with (T2AG3)7 probes. The new diploid number of 2n = 50 was associated with two different fundamental numbers (FN = 71 and 72) as a result of pericentric inversions and addition/deletion of constitutive heterochromatin. The samples from two localities (Aripuanã and Vila Rica) in the state of Mato Grosso shared 2n = 44 and FN = 52, but their karyotypes differed because of pericentric inversions. Although the single specimen from Bahia had the same diploid number as the samples from Mato Grosso, its karyotype and FN were completely distinctive. Karyological comparison of GTG-banding patterns revealed total homology between the karyotypes of the specimens from Bahia and Mato Grosso, implying the occurrence of 14 autosomal pericentric inversions. Homologies between ten of the autosomes in the karyotypes with 2n = 50 (FN = 72) and 2n = 44 (from Vila Rica, MT) were demonstrated. The differentiation between 2n = 44 and 2n = 50 involved five pericentric inversions, addition/deletion of constitutive heterochromatin in both autosomes and sex chromosomes, at least one Robertsonian rearrangement and other not detected rearrangements. Despite the remarkable number of rearrangements, interstitial telomeric sites (ITS) were not detected. Sex chromosomes also exhibited polymorphism in size and morphology.
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Affiliation(s)
- M J Silva
- Departamento de Biologia, Universidade de São Paulo, SP, Brazil.
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84
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Go Y, Rakotoarisoa G, Kawamoto Y, Randrianjafy A, Koyama N, Hirai H. PRINS analysis of the telomeric sequence in seven lemurs. Chromosome Res 2000; 8:57-65. [PMID: 10730589 DOI: 10.1023/a:1009279203886] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We examined the chromosomal localization of the telomeric sequence, (TTAGGG)n, in seven species of the lemurs and one greater galago, as an outgroup, using the primed in-situ labeling (PRINS) technique. As expected, the telomeric sequence was identified at both ends of all chromosomes of the eight prosimians. However, six species showed a signal at some pericentromeric regions involving constitutive heterochromatin as well. The pericentromeric region of chromosome 1 of Verreaux's sifaka (Propithecus verreauxi verreauxi) was labeled with a large and intense signal. The range of the signal considerably exceeded the area of DAPI positive heterochromatin. On the other hand, in the five lemurs, a large signal was detected also in the short arm of acrocentric chromosomes. Acquisition of the large block of the telomeric sequence into the acrocentric short arm might be interpretable in terms of the tandem growth of the heterochromatic short arm and the reciprocal translocation between heterochromatic short arms involving the telomeric sequence. Subsequently, it was postulated that meta- or submetacentric chromosomes possessing the telomeric sequence at the pericentromeric region could be formed by centric fusion between such acrocentric chromosomes.
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Affiliation(s)
- Y Go
- Primate Research Insitute, Kyoto University, Inuyama, Aichi, Japan
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85
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Bailey SM, Meyne J, Chen DJ, Kurimasa A, Li GC, Lehnert BE, Goodwin EH. DNA double-strand break repair proteins are required to cap the ends of mammalian chromosomes. Proc Natl Acad Sci U S A 1999; 96:14899-904. [PMID: 10611310 PMCID: PMC24745 DOI: 10.1073/pnas.96.26.14899] [Citation(s) in RCA: 294] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recent findings intriguingly place DNA double-strand break repair proteins at chromosome ends in yeast, where they help maintain normal telomere length and structure. In the present study, an essential telomere function, the ability to cap and thereby protect chromosomes from end-to-end fusions, was assessed in repair-deficient mouse cell lines. By using fluorescence in situ hybridization with a probe to telomeric DNA, spontaneously occurring chromosome aberrations were examined for telomere signal at the points of fusion, a clear indication of impaired end-capping. Telomeric fusions were not observed in any of the repair-proficient controls and occurred only rarely in a p53 null mutant. In striking contrast, chromosomal end fusions that retained telomeric sequence were observed in nontransformed DNA-PK(cs)-deficient cells, where they were a major source of chromosomal instability. Metacentric chromosomes created by telomeric fusion became even more abundant in these cells after spontaneous immortalization. Restoration of repair proficiency through transfection with a functional cDNA copy of the human DNA-PK(cs) gene reduced the number of fusions compared with a negative transfection control. Virally transformed cells derived from Ku70 and Ku80 knockout mice also displayed end-to-end fusions. These studies demonstrate that DNA double-strand break repair genes play a dual role in maintaining chromosomal stability in mammalian cells, the known role in repairing incidental DNA damage, as well as a new protective role in telomeric end-capping.
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Affiliation(s)
- S M Bailey
- Life Sciences Division, Los Alamos National Laboratory, MS M888, Los Alamos, NM 87545, USA
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86
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Abstract
The ends of mammalian chromosomes are composed of repeated DNA sequences of (TTAGGG)(n) known as telomeres. Telomerase is a ribonucleoprotein that synthesizes telomeric DNA to replenish the 50-200 bp lost during cell replication. Cellular aging and senescence are associated with a lack of telomerase activity and a critical shortening of the telomere. The objectives of this study were to confirm the presence of TTAGGG repeats on the chromosomes of bovine embryos using in situ hybridization and assess the relative amounts of telomerase activity using a telomeric repeat amplification protocol (TRAP) during oocyte maturation and early embryo development. Applying a telomere DNA probe to the chromosomes of blastocysts and adult fibroblasts, telomeres were identified on the terminal ends of the p and q arms of chromosomes in all cells examined. Immature oocytes, matured oocytes, zygotes, 2- to 5-cell embryos, 6- to 8-cell embryos, morulae, and blastocysts were lysed in NP-40 lysis buffer and telomerase activity was assayed using the TRAP assay. Telomerase activity was detected in all developmental stages examined. Relative telomerase activity (based on telomerase internal standards and positive controls) appeared to decrease during oocyte maturation and subsequent development to the 8-cell stage but significantly increased (P < 0.05) by approximately 40-fold at the morula and blastocyst stages. It was concluded that the telomeres of bovine chromosomes contain TTAGGG repeats and that telomerase activity is up-regulated in morulae and blastocysts.
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Affiliation(s)
- D H Betts
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
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87
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Kakuo S, Asaoka K, Ide T. Human is a unique species among primates in terms of telomere length. Biochem Biophys Res Commun 1999; 263:308-14. [PMID: 10491289 DOI: 10.1006/bbrc.1999.1385] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
TRF (terminal restriction fragments) length in various tissues of non-human primates such as Macaca mulatta (rhesus monkey), Macaca fuscata (Japanese monkey), Macaca fascicularis (crab-eating monkey), Pan troglodytes (common chimpanzee), and Pongo pygmaeus (orangutan) was at least 23 kb without exception, which was quite different from that of human somatic tissues (smaller than 10 kb). The distribution pattern of telomerase activity among tissues was similar between human and non-human primates, while the activity level showed some differences such as that strong telomerase activity was observed in gastrointestinal and lymphocytic tissues from non-human primates. The human appears to be a unique species among primates in terms of telomere length.
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Affiliation(s)
- S Kakuo
- Department of Cellular and Molecular Biology, Hiroshima University School of Medicine, Kasumi 1-2-3, Hiroshima, 734-8551, Japan
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88
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Metcalfe CJ, Eldridge MD, Toder R, Johnston PG. Mapping the distribution of the telomeric sequence (T2AG3)n in the Macropodoidea (Marsupialia), by fluorescence in situ hybridization. I. The swamp wallaby, Wallabia bicolor. Chromosome Res 1998; 6:603-10. [PMID: 10099873 DOI: 10.1023/a:1009249325574] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Thylogale spp. (pademelons) retain the plesiomorphic (ancestral) 2n = 22 karyotype for the marsupial family Macropodidae (kangaroos and wallabies). The swamp wallaby, Wallabia bicolor, has the most derived macropodid karyotype with the lowest chromosome number (2n = 10 female, 11 male), and a multiple sex chromosome system (XX female, XY1Y2 male). All but one of the W. bicolor chromosomes are fusion chromosomes. Two of these chromosomes, the X chromosome and chromosome 1, are composed of three plesiomorphic Thylogale-like chromosomes. The distribution of the vertebrate telomeric sequence (T2AG3)n was examined by fluorescence in situ hybridization (FISH) in both species and a 'map' of non-telomeric (T2AG3)n sites on W. bicolor chromosomes relative to Thylogale chromosomes was constructed. (T2AG3)n signals were observed at six fusion sites in the four fusions chromosomes examined, indicating that the (T2AG3)n sequence is consistently retained during fusions. The distribution of the interstitial signals on the long arm of chromosome 1 of W. bicolor and the X chromosome suggests how a combination of inversions, fusions and centromeric transpositions have resulted in interstitial telomeric sequence.
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Affiliation(s)
- C J Metcalfe
- School of Biological Sciences, Macquarie University, New South Wales, Australia.
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89
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de Jesus Silva MJ, Yonenaga-Yassuda Y. Heterogeneity and meiotic behaviour of B and sex chromosomes, banding patterns and localization of (TTAGGG)n sequences by fluorescence in situ hybridization in the neotropical water rat Nectomys (Rodentia, Cricetidae). Chromosome Res 1998; 6:455-62. [PMID: 9865784 DOI: 10.1023/a:1009248311530] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A cytogenetic study using fluorescence in situ hybridization (FISH) of telomere probes, CBG, GTG and RBG banding patterns and synaptonemal complex data was carried out in 41 specimens of Nectomys from three Brazilian states: Pernambuco, Mato Grosso and São Paulo. The specimens presented 2n = 52, 53, 56 and 57, and the differences in chromosome number were due to the presence of three different supernumeraries and also to the occurrence of tandem fusions. The tandem fusions involved chromosome pairs 3 + 11 and 5 + 24 from karyotype with 2n = 56 that originated pairs 1 and 4 in specimens with 2n = 52. Sex chromosome polymorphism was also detected, and the X presented three different morphologies, which could be explained by heterochromatin addition/deletion. FISH results revealed interstitial telomeric bands (ITBs) in a submetacentric B, but no ITB was detected in the chromosomes originated by tandem fusion. The supernumeraries presented a remarkable heterogeneity of size and morphology, constitutive heterochromatin pattern and localization of telomeric sequences. Synaptonemal complex by light and electron microscopy showed the supernumerary as an autopaired univalent. The sex chromosome pairing in meiotic cells involved the heterochromatic short arm of the X chromosome and the short arm of the Y chromosome.
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Affiliation(s)
- M J de Jesus Silva
- Departamento de Biologia, Instituto de Biociências, Universidade de São Paulo, SP, Brazil. mailto:
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90
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Abstract
The quantitative fluorescence in situ hybridization (Q-FISH) technique enables an accurate estimate of individual telomere lengths, a possibility beyond the resolution of conventional techniques. So far, Q-FISH has been used for the estimate of individual telomere lengths in human, mouse and Chinese hamster chromosomes. This analysis revealed large variations in the size of individual telomeres and a specific intra-chromosomal distribution of telomere lengths; telomeres closer to centromeres appear to be shorter than their counterparts more distant from centromeres. This observation suggests that individual telomere length may be affected by centromere position, a possibility consistent with the theory of chromosome field postulated more than 40 years ago by Lima-de-Faria. The link between the theory of chromosome field and the role of telomere-centromere relationships in the regulation of telomere length is discussed in this article.
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Affiliation(s)
- P Slijepcevic
- School of Biomedical Sciences, Bute Medical Buildings, University of St. Andrews, St. Andrews KY16 9TS, UK.
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91
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Lee HW, Blasco MA, Gottlieb GJ, Horner JW, Greider CW, DePinho RA. Essential role of mouse telomerase in highly proliferative organs. Nature 1998; 392:569-74. [PMID: 9560153 DOI: 10.1038/33345] [Citation(s) in RCA: 946] [Impact Index Per Article: 36.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We have investigated the role of the enzyme telomerase in highly proliferative organs in successive generations of mice lacking telomerase RNA. Late-generation animals exhibited defective spermatogenesis, with increased programmed cell death (apoptosis) and decreased proliferation in the testis. The proliferative capacity of haematopoietic cells in the bone marrow and spleen was also compromised. These progressively adverse effects coincided with substantial erosion of telomeres (the termini of eukaryotic chromosomes) and fusion and loss of chromosomes. These findings indicate an essential role for telomerase, and hence telomeres, in the maintenance of genomic integrity and in the long-term viability of high-renewal organ systems.
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Affiliation(s)
- H W Lee
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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92
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Garagna S, Ronchetti E, Mascheretti S, Crovella S, Formenti D, Rumpler Y, Manfredi Romanini MG. Non-telomeric chromosome localization of (TTAGGG)n repeats in the genus Eulemur. Chromosome Res 1997; 5:487-91. [PMID: 9421267 DOI: 10.1023/a:1018425215516] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The chromosomal distribution of the (TTAGGG)n telomeric repetitive sequences was studied in the Malagasy species Eulemur fulvus fulvus (2n = 60), Eulemur rubriventer (2n = 50), Eulemur coronatus (2n = 46) and Eulemur macaco (2n = 44). These sequences hybridize to the telomeres of all chromosomes of the four species and also to the pericentromeres of all chromosomes of E. fulvus, E. coronatus and E. macaco, with the exception of the pericentromeres of E. coronatus and E. macaco chromosomes 9, the homeologous E. fulvus chromosomes 2 and E. macaco chromosomes 1. In E. rubriventer only a very weak signal was detected at the pericentromeres of a few chromosomes. In E. fulvus, E. coronatus and E. macaco, non-telomeric (TTAGGG)n sequences collocalize with constitutive heterochromatin. The interspecific differences of the hybridization pattern of (TTAGGG)n sequences at the pericentromeres suggest that E. rubriventer branched off the common trunk before amplification of endogenous (TTAGGG)n sequences occurred in pericentromeric regions.
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Affiliation(s)
- S Garagna
- Dipartimento di Biologia Animale, Universita degli Studi di Pavia, Italia
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93
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Blasco MA, Lee HW, Hande MP, Samper E, Lansdorp PM, DePinho RA, Greider CW. Telomere shortening and tumor formation by mouse cells lacking telomerase RNA. Cell 1997; 91:25-34. [PMID: 9335332 DOI: 10.1016/s0092-8674(01)80006-4] [Citation(s) in RCA: 1556] [Impact Index Per Article: 57.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
To examine the role of telomerase in normal and neoplastic growth, the telomerase RNA component (mTR) was deleted from the mouse germline. mTR-/- mice lacked detectable telomerase activity yet were viable for the six generations analyzed. Telomerase-deficient cells could be immortalized in culture, transformed by viral oncogenes, and generated tumors in nude mice following transformation. Telomeres were shown to shorten at a rate of 4.8+/-2.4 kb per mTR-/- generation. Cells from the fourth mTR-/- generation onward possessed chromosome ends lacking detectable telomere repeats, aneuploidy, and chromosomal abnormalities, including end-to-end fusions. These results indicate that telomerase is essential for telomere length maintenance but is not required for establishment of cell lines, oncogenic transformation, or tumor formation in mice.
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Affiliation(s)
- M A Blasco
- Cold Spring Harbor Laboratory, New York 11724, USA
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94
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Fagundes V, Vianna-Morgante AM, Yonenaga-Yassuda Y. Telomeric sequences localization and G-banding patterns in the identification of a polymorphic chromosomal rearrangement in the rodent Akodon cursor (2n=14,15 and 16). Chromosome Res 1997; 5:228-32. [PMID: 9244449 DOI: 10.1023/a:1018463401887] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Akodon cursor is an exceptional example of high chromosomal variability, displaying diploid numbers from 14 to 16 and fundamental numbers (FN) from 18 to 26 as the result of a complex rearrangement in par 1 and pericentric inversions in three autosomal pairs. The difference in the diploid number is due to the presence of a large metacentric pair 1 in the 2n=14 karyotype, a large metacentric 1 and two different submetacentrics (1a and 1b) in 2n=15 and 1a and 1b submetacentric pairs in homozygosis in the 2n = 16 karyotype. Chromosomes 1a and 1b share homology with the short and long arms of the large metacentric 1 respectively. In this paper, evidence based on fluorescence in situ hybridization (FISH) with telomeric sequences and G-banding indicates that pericentric inversions and fusion of chromosomes 1a and 1b are the probable rearrangements giving rise to the large metacentric 1.
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Affiliation(s)
- V Fagundes
- Departamento de Biologia, Instituto de Biociências, Universidade de São Paulo, Brazil.
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95
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Marescalchi O, Scali V. Chromosomal and NOR patterns in the polyclonal stick insect Bacillus atticus atticus (Insecta; Phasmatodea). Genome 1997; 40:261-70. [DOI: 10.1139/g97-037] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Bacillus atticus atticus is a complex of thelytokous parthenogens, related to the bisexual Bacillus grandii, that ranges from Sardinia to Near Eastern countries. Karyotypic and cytogenetic differentiation of the B. atticus atticus diploid unisexual "isolates" is really higher than expected. Its standard karyotype has 2n = 34 chromosomes, but several instances of repatterned or even aneuploid complements have been found. The number and location of silver-stained NORs are particularly intriguing, since in addition to homozygous NOR patterns, simple or double hemizygous strains are found spread over specific and wide regions. The odd patterns are not due to Ag-NOR staining technique artifacts, since the FISH method, using rDNA probes, apparently labels the same ribosomal clusters. Transpositions and translocations have been suggested to account for some NOR patterns, but hybridizations between different NOR-bearing races are also a possible cause. This chromosomal survey clearly contributes to a better understanding of B. atticus phylogeny.Key words: aneuploidy, interracial hybrids, karyotype repatterning, NOR techniques, unisexuals.
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96
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Abstract
Mouse telomeres are on average longer than those of man, raising questions regarding the link between telomere loss and replicative senescence in mice and the requirement for telomerase activity for mouse cell immortalisation. However, the emerging data on telomerase activity during tumorigenesis in the mouse must be interpreted in the context of the very different structure of mouse telomeres. It will be argued here that the evidence for a casual link between telomere loss and replicative senescence is weak in the mouse, with the observed upregulation of telomerase activity in mouse tumours perhaps instead reflecting co-ordinated regulatory changes in tumour cells. Its absence would be consistent with evolutionary considerations, which hypothesise that such a link is an additional layer of control against tumour formation that has evolved in man. The very different genomic substrates for telomerase in humans and mice mean that the initial phenotype of a telomerase knock-out mouse does not necessarily critically address the existence of a link between telomerase and tumorigenesis in man.
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Affiliation(s)
- D Kipling
- Department of Pathology, University of Wales College of Medicine, Cardiff, U.K
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97
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Abstract
Fluorescent in situ hybridization technology is one of the most exciting and versatile research tools to be developed in recent years. It has enabled research to progress at a phenomenal rate in diverse areas of basic research as well as in clinical medicine. Fluorescent in situ hybridization has applications in physical mapping, the study of nuclear architecture and chromatin packaging, and the investigation of fundamental principles of biology such as DNA replication, RNA processing, gene amplification, gene integration and chromatin elimination. This review highlights some of these areas and provides source material for the reader who seeks more information on a specific field.
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Affiliation(s)
- H H Heng
- Department of Biology, York University, Downsview, Ontario, Canada
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98
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Volobouev V, Gautun JC, Sicard B, Tranier M. The chromosome complement of Acomys spp. (Rodentia, Muridae) from Oursi, Burkina Faso--the ancestral karyotype of the cahirinus-dimidiatus group? Chromosome Res 1996; 4:526-30. [PMID: 8939364 DOI: 10.1007/bf02261780] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We present here data on chromosome banding analysis (R- and C-bands) of Acomys sp. (Rodentia, Muridae) from Oursi, Burkina Faso, characterized by 2n = FN = 68 and comparison of its banding patterns with those of Acomys dimidiatus from Saudi Arabia (2n = 38, FN = 70), studied previously. The study revealed complete homology between acrocentric chromosomes of Acomys sp. and chromosome arms of 16 pairs of metacentric and two pairs of acrocentric chromosomes of A. dimidiatus. In addition to monobrachial homology, one tandem translocation accompanied by a centromeric shift was identified in the karyotype of the latter species. The data obtained show that karyotypes of all the species of the Acomys cahirinus-dimidiatus group studied previously may be derived from that of Acomys sp. from Oursl by means of numerous non-homologous Rb translocations and 1-2 tandem transiocations, and thus its karyotype may be considered as ancestral for the cahirinus-dimidiatus group.
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Affiliation(s)
- V Volobouev
- Institut Curie, Section de Biologie, Paris, France.
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99
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Abstract
Telomeres cap and protect the ends of chromosomes from degradation and illegitimate recombination. The termini of a linear template cannot, however, be completely replicated by conventional DNA-dependent DNA polymerases, and thus in the absence of a mechanisms to counter this effect, telomeres of eukaryotic cells shorten every round of DNA replication. In humans and possibly other higher eukaryotes, telomere shortening may have been adopted to limit the life span of somatic cells. Human somatic cells have a finite proliferative capacity and enter a viable growth arrested state called senescence. Life span appears to be governed by cell division, not time. The regular loss of telomeric DNA could therefore serve as a mitotic clock in the senescence programme, counting cell divisions. In most eukaryotic organisms, however, telomere shortening can be countered by the de novo addition of telomeric repeats by the enzyme telomerase. Cells which are "immortal' such as the human germ line or tumour cell lines, established mouse cells, yeast and ciliates, all maintain a stable telomere length through the action of telomerase. Abolition of telomerase activity in such cells nevertheless results in telomere shortening, a process that eventually destabilizes the ends of chromosomes, leading to genomic instability and cell growth arrest or death. Therefore, loss of terminal DNA sequences may limit cell life span by two mechanisms: by acting as a mitotic clock and by denuding chromosomes of protective telomeric DNA necessary for cell viability.
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Affiliation(s)
- C M Counter
- Whitehead Institute for Biomedical Research (Weinberg Lab), Nine Cambridge Center, MA 02142-1479, USA.
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100
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Broccoli D, Godley LA, Donehower LA, Varmus HE, de Lange T. Telomerase activation in mouse mammary tumors: lack of detectable telomere shortening and evidence for regulation of telomerase RNA with cell proliferation. Mol Cell Biol 1996; 16:3765-72. [PMID: 8668193 PMCID: PMC231372 DOI: 10.1128/mcb.16.7.3765] [Citation(s) in RCA: 125] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Activation of telomerase in human cancers is thought to be necessary to overcome the progressive loss of telomeric DNA that accompanies proliferation of normal somatic cells. According to this model, telomerase provides a growth advantage to cells in which extensive terminal sequence loss threatens viability. To test these ideas, we have examined telomere dynamics and telomerase activation during mammary tumorigenesis in mice carrying a mouse mammary tumor virus long terminal repeat-driven Wnt-1 transgene. We also analyzed Wnt-1-induced mammary tumors in mice lacking p53 function. Normal mammary glands, hyperplastic mammary glands, and mammary carcinomas all had the long telomeres (20 to 50 kb) typical of Mus musculus and did not show telomere shortening during tumor development. Nevertheless, telomerase activity and the RNA component of the enzyme were consistently upregulated in Wnt-1-induced mammary tumors compared with normal and hyperplastic tissues. The upregulation of telomerase activity and RNA also occurred during tumorigenesis in p53-deficient mice. The expression of telomerase RNA correlated strongly with histone H4 mRNA in all normal tissues and tumors, indicating that the RNA component of telomerase is regulated with cell proliferation. Telomerase activity in the tumors was elevated to a greater extent than telomerase RNA, implying that the enzymatic activity of telomerase is regulated at additional levels. Our data suggest that the mechanism of telomerase activation in mouse mammary tumors is not linked to global loss of telomere function but involves multiple regulatory events including upregulation of telomerase RNA in proliferating cells.
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MESH Headings
- Animals
- Base Sequence
- Enzyme Activation
- Female
- Gene Expression Regulation, Neoplastic
- Histones/biosynthesis
- Humans
- Hyperplasia
- Mammary Glands, Animal/metabolism
- Mammary Glands, Animal/pathology
- Mammary Neoplasms, Experimental/enzymology
- Mammary Neoplasms, Experimental/pathology
- Mammary Tumor Virus, Mouse
- Mice
- Mice, Transgenic
- Mitogens/genetics
- Molecular Sequence Data
- Oligodeoxyribonucleotides
- Polymerase Chain Reaction
- Proto-Oncogene Proteins/biosynthesis
- Proto-Oncogene Proteins/genetics
- RNA Polymerase III/metabolism
- RNA, Messenger/biosynthesis
- Repetitive Sequences, Nucleic Acid
- Telomerase/biosynthesis
- Telomerase/metabolism
- Transcription, Genetic
- Wnt Proteins
- Wnt1 Protein
- Zebrafish Proteins
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Affiliation(s)
- D Broccoli
- Laboratory for Cell Biology and Genetics, The Rockfeller University, New York, New York 10021, USA
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