Distribution of telomeric (TTAGGG)n sequences in avian chromosomes

Nanda, Indrajit; Schrama, David; Feichtinger, W.; Haaf, Thomas; Schartl, Manfred; Schmid, Michael

doi:10.1007/s00412-002-0206-4

Cited by 132 publications

(170 citation statements)

References 41 publications

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“…The samples were dehydrated with incubation in ethanol at 70%, 90%, and 100% for 2 min each. Probes were hybridized at 37°C for at least 24 h as reported (15). For visualizing telomeric repeats, the probe was identified with Alexa Fluor 568-labeled streptavidin.…”

Section: Methodsmentioning

confidence: 99%

“…We flanked both the uninsulated and the core cHS4-insulated transgene with 1.6 kb of telomeric (TTAGGG) n repeats ( Fig. 2A) (14,15). To analyze whether the transgene was integrated in a telomeric region, we evaluated the colocalization of telomeric repeats with the transgene by in situ hybridization (Fig.…”

Section: Transgene Targeting To Telomeric Regions In Chicken Hd3mentioning

confidence: 99%

“…7). We believe that the avian genome represents an attractive model for TPE because of its high density of telomeric (TTAGGG) n repeats in macrochromosomes and microchromosomes (15).…”

Section: Transgene Targeting To Telomeric Regions In Chicken Hd3mentioning

confidence: 99%

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Protection against telomeric position effects by the chicken cHS4 β-globin insulator

Rincón‐Arano

Furlan-Magaril

Recillas‐Targa

2007

Proc. Natl. Acad. Sci. U.S.A.

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Epigenetic silencing of genes relocated near telomeres, termed telomeric position effect, has been extensively studied in yeast and more recently in vertebrates. However, protection of a transgene against telomeric position effects by chromatin insulators has not yet been addressed. In this work we investigated the capacity of the chicken ␤-globin insulator cHS4 to shield a transgene against silencing by telomeric heterochromatin. Using telomeric repeats, we targeted transgene integration into telomeres of the chicken cell line HD3. When the chicken cHS4 insulator is incorporated to the transgene, we observe a sustained gene expression of singlecopy integrants that can be maintained for >100 days of continuous culture. However, uninsulated single-copy clones showed an accelerated gene expression extinction profile. Unexpectedly, telomeric silencing was not reversed with trichostatin A or nicotidamine. In contrast, significant reactivation was obtained with 5-aza-2 -deoxycytidine, consistent with the subtelomeric DNA methylation status. Strikingly, insulated transgenes integrated into telomeric regions were enriched in histone methylation, such as H3K4me2 and H3K79me2, but not in histone acetylation. Furthermore, the cHS4 insulator counteracts telomeric position effects in an upstream stimulatory factor-independent manner. Our results suggest that this insulator has the capacity to adapt to different chromatin propagation signals in distinct insertional epigenome environments.chromatin insulator ͉ DNA methylation ͉ heterochromatin ͉ histone modifications ͉ epigenetic silencing

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Section: Methodsmentioning

confidence: 99%

Section: Transgene Targeting To Telomeric Regions In Chicken Hd3mentioning

confidence: 99%

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Protection against telomeric position effects by the chicken cHS4 β-globin insulator

Rincón‐Arano

Furlan-Magaril

Recillas‐Targa

2007

Proc. Natl. Acad. Sci. U.S.A.

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“…For example, a number of studies have documented strong correspondence between whole chromosomes of different bird species using fluorescent in situ hybridization techniques (Shetty et al 1999;Raudsepp et al 2002;Guttenbach et al 2003). Despite the apparent conservatism of the avian karyotype, these studies have also uncovered examples of chromsome fusion and fission, and homologies between macroand microchromosomes (Grü tzner et al 2001;Nanda et al 2002). Although the era of avian 'cytophylogenetics' has barely begun, the field can take confidence from new methodological and analytical advances that promise to speed up data acquisition and analysis considerably, as well as examples from mammals (Robinson et al 2004) that clearly demonstrate the utility of karyological data for higher-level systematics.…”

Section: The Future: the Tools Of Phylogenomics (A) Contiguous Versusmentioning

confidence: 99%

Phylogenetics of modern birds in the era of genomics

2005

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In the 14 years since the first higher-level bird phylogenies based on DNA sequence data, avian phylogenetics has witnessed the advent and maturation of the genomics era, the completion of the chicken genome and a suite of technologies that promise to add considerably to the agenda of avian phylogenetics. In this review, we summarize current approaches and data characteristics of recent higher-level bird studies and suggest a number of as yet untested molecular and analytical approaches for the unfolding tree of life for birds. A variety of comparative genomics strategies, including adoption of objective quality scores for sequence data, analysis of contiguous DNA sequences provided by large-insert genomic libraries, and the systematic use of retroposon insertions and other rare genomic changes all promise an integrated phylogenetics that is solidly grounded in genome evolution. The avian genome is an excellent testing ground for such approaches because of the more balanced representation of single-copy and repetitive DNA regions than in mammals. Although comparative genomics has a number of obvious uses in avian phylogenetics, its application to large numbers of taxa poses a number of methodological and infrastructural challenges, and can be greatly facilitated by a 'community genomics' approach in which the modest sequencing throughputs of single PI laboratories are pooled to produce larger, complementary datasets. Although the polymerase chain reaction era of avian phylogenetics is far from complete, the comparative genomics era-with its ability to vastly increase the number and type of molecular characters and to provide a genomic context for these characters-will usher in a host of new perspectives and opportunities for integrating genome evolution and avian phylogenetics.

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“…Chromosomal sites composed of telomeric repeats localized apart from the telomeres, also known as interstitial or intrachromosomal telomeric sequences (ITSs) or repeats (ITRs), have been detected in several animals (Meyne et al 1990, Nanda et al 2002, Rovatsos et al 2015, Schmid and Steinlein 2016 and plants (Tek andJiang 2004, He et al 2013). Based on the genomic location and sequence organization, especially in the number of telomeric repeats, Ruiz-Herrera et al (2008) classified the ITSs in short ITSs (s-ITSs) and heterochromatic ITS (het-ITS).…”

Section: Introductionmentioning

confidence: 99%