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The heterochromatic chromosome caps in great apes impact telomere metabolism.

Novo C, Arnoult N, Bordes WY, Castro-Vega L, Gibaud A, Dutrillaux B, Bacchetti S, Londoño-Vallejo A - Nucleic Acids Res. (2013)

Bottom Line: In contrast with the limited sequence divergence accumulated after separation of higher primate lineages, marked cytogenetic variation has been associated with the genome evolution in these species.Studying the impact of such structural variations on defined molecular processes can provide valuable insights on how genome structural organization contributes to organismal evolution.In gorilla, on the other hand, a proportion of the subtelomeric heterochromatic caps present in most chromosome arms are associated with large blocks of telomere-like sequences that follow a replication program different from that of bona fide telomeres.

View Article: PubMed Central - PubMed

Affiliation: Telomeres and Cancer laboratory, 'Equipe Labellisée Ligue contre le Cancer', UMR3244, Institut Curie, 26 rue d'Ulm, 75248 Paris, France.

ABSTRACT
In contrast with the limited sequence divergence accumulated after separation of higher primate lineages, marked cytogenetic variation has been associated with the genome evolution in these species. Studying the impact of such structural variations on defined molecular processes can provide valuable insights on how genome structural organization contributes to organismal evolution. Here, we show that telomeres on chromosome arms carrying subtelomeric heterochromatic caps in the chimpanzee, which are completely absent in humans, replicate later than telomeres on chromosome arms without caps. In gorilla, on the other hand, a proportion of the subtelomeric heterochromatic caps present in most chromosome arms are associated with large blocks of telomere-like sequences that follow a replication program different from that of bona fide telomeres. Strikingly, telomere-containing RNA accumulates extrachromosomally in gorilla mitotic cells, suggesting that at least some aspects of telomere-containing RNA biogenesis have diverged in gorilla, perhaps in concert with the evolution of heterochromatic caps in this species.

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TERRA accumulates extrachromosomally in gorilla mitotic cells. Telomeric FISH on metaphasic spreads revealed the presence of extrachromosomal telomeric-sequences. These extrachromosomal sequences are G-rich, as they are exclusively detected with C-rich probes (upper panel, left) and not with G-rich probes (upper panel, right). These molecules correspond to single-stranded telomeric-repeats containing RNA (TERRA), as they are RNase I sensitive (bottom panel, left), and their detection does not require a denaturation step (upper panel, second from left).
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gkt169-F3: TERRA accumulates extrachromosomally in gorilla mitotic cells. Telomeric FISH on metaphasic spreads revealed the presence of extrachromosomal telomeric-sequences. These extrachromosomal sequences are G-rich, as they are exclusively detected with C-rich probes (upper panel, left) and not with G-rich probes (upper panel, right). These molecules correspond to single-stranded telomeric-repeats containing RNA (TERRA), as they are RNase I sensitive (bottom panel, left), and their detection does not require a denaturation step (upper panel, second from left).

Mentions: In the course of telomeric FISH analyses carried out with gorilla cells, we noticed the presence of abundant extrachromosomic telomeric signals, a feature normally absent in human cells and not observed in chimpanzee. These signals were detected exclusively with C-rich (both LNA and PNA) telomeric probes, suggesting that they contained G-rich telomeric repeats of single-stranded composition (Figure 3). That these molecules were indeed single stranded was further indicated by the fact that their detection did not require a denaturation step (Figure 3).Figure 3.


The heterochromatic chromosome caps in great apes impact telomere metabolism.

Novo C, Arnoult N, Bordes WY, Castro-Vega L, Gibaud A, Dutrillaux B, Bacchetti S, Londoño-Vallejo A - Nucleic Acids Res. (2013)

TERRA accumulates extrachromosomally in gorilla mitotic cells. Telomeric FISH on metaphasic spreads revealed the presence of extrachromosomal telomeric-sequences. These extrachromosomal sequences are G-rich, as they are exclusively detected with C-rich probes (upper panel, left) and not with G-rich probes (upper panel, right). These molecules correspond to single-stranded telomeric-repeats containing RNA (TERRA), as they are RNase I sensitive (bottom panel, left), and their detection does not require a denaturation step (upper panel, second from left).
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3643582&req=5

gkt169-F3: TERRA accumulates extrachromosomally in gorilla mitotic cells. Telomeric FISH on metaphasic spreads revealed the presence of extrachromosomal telomeric-sequences. These extrachromosomal sequences are G-rich, as they are exclusively detected with C-rich probes (upper panel, left) and not with G-rich probes (upper panel, right). These molecules correspond to single-stranded telomeric-repeats containing RNA (TERRA), as they are RNase I sensitive (bottom panel, left), and their detection does not require a denaturation step (upper panel, second from left).
Mentions: In the course of telomeric FISH analyses carried out with gorilla cells, we noticed the presence of abundant extrachromosomic telomeric signals, a feature normally absent in human cells and not observed in chimpanzee. These signals were detected exclusively with C-rich (both LNA and PNA) telomeric probes, suggesting that they contained G-rich telomeric repeats of single-stranded composition (Figure 3). That these molecules were indeed single stranded was further indicated by the fact that their detection did not require a denaturation step (Figure 3).Figure 3.

Bottom Line: In contrast with the limited sequence divergence accumulated after separation of higher primate lineages, marked cytogenetic variation has been associated with the genome evolution in these species.Studying the impact of such structural variations on defined molecular processes can provide valuable insights on how genome structural organization contributes to organismal evolution.In gorilla, on the other hand, a proportion of the subtelomeric heterochromatic caps present in most chromosome arms are associated with large blocks of telomere-like sequences that follow a replication program different from that of bona fide telomeres.

View Article: PubMed Central - PubMed

Affiliation: Telomeres and Cancer laboratory, 'Equipe Labellisée Ligue contre le Cancer', UMR3244, Institut Curie, 26 rue d'Ulm, 75248 Paris, France.

ABSTRACT
In contrast with the limited sequence divergence accumulated after separation of higher primate lineages, marked cytogenetic variation has been associated with the genome evolution in these species. Studying the impact of such structural variations on defined molecular processes can provide valuable insights on how genome structural organization contributes to organismal evolution. Here, we show that telomeres on chromosome arms carrying subtelomeric heterochromatic caps in the chimpanzee, which are completely absent in humans, replicate later than telomeres on chromosome arms without caps. In gorilla, on the other hand, a proportion of the subtelomeric heterochromatic caps present in most chromosome arms are associated with large blocks of telomere-like sequences that follow a replication program different from that of bona fide telomeres. Strikingly, telomere-containing RNA accumulates extrachromosomally in gorilla mitotic cells, suggesting that at least some aspects of telomere-containing RNA biogenesis have diverged in gorilla, perhaps in concert with the evolution of heterochromatic caps in this species.

Show MeSH
Related in: MedlinePlus