Interstitial Telomeric Repeats Are Rare in Turtles

Telomeres are nucleoprotein complexes protecting chromosome ends in most eukaryotic organisms. In addition to chromosome ends, telomeric-like motifs can be accumulated in centromeric, pericentromeric and intermediate (i.e., between centromeres and telomeres) positions as so-called interstitial telomeric repeats (ITRs). We mapped the distribution of (TTAGGG)_n repeats in the karyotypes of 30 species from nine families of turtles using fluorescence in situ hybridization. All examined species showed the expected terminal topology of telomeric motifs at the edges of chromosomes. We detected ITRs in only five species from three families. Combining our and literature data, we inferred seven independent origins of ITRs among turtles. ITRs occurred in turtles in centromeric positions, often in several chromosomal pairs, in a given species. Their distribution does not correspond directly to interchromosomal rearrangements. Our findings support that centromeres and non-recombining parts of sex chromosomes are very dynamic genomic regions, even in turtles, a group generally thought to be slowly evolving. However, in contrast to squamate reptiles (lizards and snakes), where ITRs were found in more than half of the examined species, and birds, the presence of ITRs is generally rare in turtles, which agrees with the expected low rates of chromosomal rearrangements and rather slow karyotype evolution in this group. View Full-Text

Keywords: evolution; FISH; in situ hybridization; ITRs; interstitial telomeric repeats; ITSs; interstitial telomeric sequences; karyotype; telomeres; turtles

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MDPI and ACS Style

Clemente, L.; Mazzoleni, S.; Pensabene Bellavia, E.; Augstenová, B.; Auer, M.; Praschag, P.; Protiva, T.; Velenský, P.; Wagner, P.; Fritz, U.; Kratochvíl, L.; Rovatsos, M. Interstitial Telomeric Repeats Are Rare in Turtles. Genes 2020, 11, 657. https://doi.org/10.3390/genes11060657

AMA Style

Clemente L, Mazzoleni S, Pensabene Bellavia E, Augstenová B, Auer M, Praschag P, Protiva T, Velenský P, Wagner P, Fritz U, Kratochvíl L, Rovatsos M. Interstitial Telomeric Repeats Are Rare in Turtles. Genes. 2020; 11(6):657. https://doi.org/10.3390/genes11060657

Chicago/Turabian Style

Clemente, Lorenzo, Sofia Mazzoleni, Eleonora Pensabene Bellavia, Barbora Augstenová, Markus Auer, Peter Praschag, Tomáš Protiva, Petr Velenský, Philipp Wagner, Uwe Fritz, Lukáš Kratochvíl, and Michail Rovatsos. 2020. "Interstitial Telomeric Repeats Are Rare in Turtles" Genes 11, no. 6: 657. https://doi.org/10.3390/genes11060657

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Interstitial Telomeric Repeats Are Rare in Turtles

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