Mapping the Distribution of the Telomeric Sequence (T2AG3)nin the 2n = 14 Ancestral Marsupial Complement and in the Macropodines (Marsupialia: Macropodidae) by fluorescence in situ hybridization

Metcalfe, Cushla J.; Eldridge, Mark D. B.; Johnston, P. G.

doi:10.1023/b:chro.0000034133.77878.88

Cited by 40 publications

(44 citation statements)

References 39 publications

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“…C-and G-banding: C-banding was performed as per Metcalfe et al (2004). GTG-banding was performed as per Rens et al (2003) with the modification of using 0.4% trypsin solution for a time of 45 sec.…”

Section: Microdissection and Microcloningmentioning

confidence: 99%

Cytogenetic and Molecular Evaluation of Centromere-Associated DNA Sequences From a Marsupial (Macropodidae:Macropus rufogriseus) X Chromosome

et al. 2006

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The constitution of the centromeric portions of the sex chromosomes of the red-necked wallaby, Macropus rufogriseus (family Macropodidae, subfamily Macropodinae), was investigated to develop an overview of the sequence composition of centromeres in a marsupial genome that harbors large amounts of centric and pericentric heterochromatin. The large, C-band-positive centromeric region of the X chromosome was microdissected and the isolated DNA was microcloned. Further sequence and cytogenetic analyses of three representative clones show that all chromosomes in this species carry a 178-bp satellite sequence containing a CENP-B DNA binding domain (CENP-B box) shown herein to selectively bind marsupial CENP-B protein. Two other repeats isolated in this study localize specifically to the sex chromosomes yet differ in copy number and intrachromosomal distribution. Immunocytohistochemistry assays with anti-CENP-E, anti-CREST, anti-CENP-B, and anti-trimethyl-H3K9 antibodies defined a restricted point localization of the outer kinetochore at the functional centromere within an enlarged pericentric and heterochromatic region. The distribution of these repeated sequences within the karyotype of this species, coupled with the apparent high copy number of these sequences, indicates a capacity for retention of large amounts of centromere-associated DNA in the genome of M. rufogriseus. D URING mitosis and meiosis in mammalian cellscentromeres are the chromosomal sites of spindle attachment, mediating the interaction between chromosomes and the cellular machinery responsible for the faithful segregation of nuclear DNA. Identification of the centromere as the site of spindle attachment is dependent on the formation of the kinetochore protein complex, a layered structure of over 30 components (reviewed in Fukagawa 2004). In eukaryotes, centromeric DNA is constitutively heterochromatic and is organized into megabases of tandem satellite DNA arrays. To date, few mammalian centromeres have been characterized in detail, leaving gaps in our understanding of the structure and evolution of this portion of the genome.Recently Schueler et al. (2001) conducted large-scale physical mapping of the human X centromere and found that it contained units of satellite sequence (171 bp in length) organized into concatomers that formed larger blocks of repeated segments several megabases in length. The long-range physical map for this region supports proposed models in which tandem arrays of satellite sequences characterize centromeric regions in higher eukaryotes (Sumner 2003). The study concluded that a correlation exists between the degeneracy of satellite sequences and the location of these sequences relative to the functional centromere: the more distal a satellite relative to the centromere, the more degenerate the sequence (Schueler et al. 2001).

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Section: Microdissection and Microcloningmentioning

confidence: 99%

Cytogenetic and Molecular Evaluation of Centromere-Associated DNA Sequences From a Marsupial (Macropodidae:Macropus rufogriseus) X Chromosome

et al. 2006

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“…Interestingly, telomeric DNA repeats are not restricted only to chromosome ends, but have also been found interstitially along chromosomes (Meyne et al 1990;Nanda and Schmid 1994;Abuín et al 1996;Metcalfe et al 1998). Two kinds of interstitial telomere sites (ITSs) have been defined: short ITSs, usually interspersed in the genome, and large ITSs, mainly located within or surrounding pericentromeric regions.…”

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confidence: 99%

Chromatin Organization and Remodeling of Interstitial Telomeric Sites During Meiosis in the Mongolian Gerbil (Meriones unguiculatus)

et al. 2014

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Telomeric DNA repeats are key features of chromosomes that allow the maintenance of integrity and stability in the telomeres. However, interstitial telomere sites (ITSs) can also be found along the chromosomes, especially near the centromere, where they may appear following chromosomal rearrangements like Robertsonian translocations. There is no defined role for ITSs, but they are linked to DNA damage-prone sites. We were interested in studying the structural organization of ITSs during meiosis, a kind of cell division in which programmed DNA damage events and noticeable chromatin reorganizations occur. Here we describe the presence of highly amplified ITSs in the pericentromeric region of Mongolian gerbil (Meriones unguiculatus) chromosomes. During meiosis, ITSs show a different chromatin conformation than DNA repeats at telomeres, appearing more extended and accumulating heterochromatin markers. Interestingly, ITSs also recruit the telomeric proteins RAP1 and TRF1, but in a stage-dependent manner, appearing mainly at late prophase I stages. We did not find a specific accumulation of DNA repair factors to the ITSs, such as gH2AX or RAD51 at these stages, but we could detect the presence of MLH1, a marker for reciprocal recombination. However, contrary to previous reports, we did not find a specific accumulation of crossovers at ITSs. Intriguingly, some centromeric regions of metacentric chromosomes may bind the nuclear envelope through the association to SUN1 protein, a feature usually performed by telomeres. Therefore, ITSs present a particular and dynamic chromatin configuration in meiosis, which could be involved in maintaining their genetic stability, but they additionally retain some features of distal telomeres, provided by their capability to associate to telomere-binding proteins.

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“…A 2n = 22 karyotype, is thought to be an ancestral for the marsupial family Macropodidae (kangaroos and wallabies) (Metcalfe et al 2007). In the swamp wallaby (Wallabia bicolor) (2n= 10 in female, 2n= 11 in male) telomeric DNA sequences were retained at the fusion sites in four chromosomes formed in the course of centric fusions (Metcalfe et al, 1998). The lowest chromosome number exhibited in the mammalian species equals 6/7 (female/male) and is observed in the Indian muntjac deer (Muntiacus muntjak vaginalis MMV).…”

Section: Internally Located Telomeric Repeat Sequences As Relicts Of mentioning

confidence: 99%

Genomic Distribution of Telomeric DNA Sequences – What Do We Learn from Fish About Telomere Evolution?

Ocalewicz¹

2012

Reviews on Selected Topics of Telomere Biology

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Mapping the Distribution of the Telomeric Sequence (T₂AG₃)_nin the 2n = 14 Ancestral Marsupial Complement and in the Macropodines (Marsupialia: Macropodidae) by fluorescence in situ hybridization

Cited by 40 publications

References 39 publications

Cytogenetic and Molecular Evaluation of Centromere-Associated DNA Sequences From a Marsupial (Macropodidae:Macropus rufogriseus) X Chromosome

Cytogenetic and Molecular Evaluation of Centromere-Associated DNA Sequences From a Marsupial (Macropodidae:Macropus rufogriseus) X Chromosome

Chromatin Organization and Remodeling of Interstitial Telomeric Sites During Meiosis in the Mongolian Gerbil (Meriones unguiculatus)

Genomic Distribution of Telomeric DNA Sequences – What Do We Learn from Fish About Telomere Evolution?

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