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

Ocalewicz, Konrad

doi:10.5772/38397

Cited by 5 publications

(3 citation statements)

References 115 publications

(138 reference statements)

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“…Telomeric sequences are, however, specific not only to chromosomal ends, but have also been identified within chromosomes in areas where they do not provide a protective function. These interstitial telomeric sequences (ITSs) have been observed in many different organisms [e.g., Meyne et al, 1990;Go et al, 2000;Nanda et al, 2002;Ruiz-Herrera et al, 2002;Dobigny et al, 2003;Tek and Jiang, 2004;Zhdanova et al, 2005;Metcalfe et al, 2007;Ocalewicz, 2012;Nagamachi et al, 2013;Rovatsos et al, 2015], and several hypotheses have been advanced to explain their presence [for a review, see Ruiz-Herrera et al, 2008]. At least 2 types of ITSs can be distinguished: "short ITSs," typically composed of a few (TTAGGG) hexamers, inserted at internal sites of the chromosomes following events of double-strand breaks and their subsequent repair [Nergadze et al, 2004[Nergadze et al, , 2007 and "long ITSs," of several kb, localized mainly in the pericentromeric region where they represent either (i) the remnants of ancestral telomeres following chromosomal rearrangements [e.g., Lee et al, 1993;Fagundes and Yonenaga-Yassuda, 1998;Metcalfe et al, 2002;Dobigny et al, 2003;Hartmann and Scherthan, 2004] or (ii) a component of satellite DNA in the constitutive heterochromatin and are therefore not necessarily related to past fusion events [e.g., Go et al, 2000;Pagnozzi et al, 2002;Ventura et al, 2006].…”

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confidence: 99%

Extensive Amplification of Telomeric Repeats in the Karyotypically Highly Diverse African Pygmy Mice

Colomina¹,

Catalan²,

Britton‐Davidian³

et al. 2017

Cytogenet Genome Res

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Telomeres are ribonucleoprotein structures protecting the physical ends of eukaryotic chromosomes. However, telomeric sequences can also occur at non-terminal regions of chromosomes, forming the so-called interstitial telomeric sequences (ITSs). Some ITSs are considered as relics of past chromosomal rearrangements and as such provide important insights into karyotype evolution. By FISH, we explored the distribution of telomeric motifs in the genome of a complex of mammalian species that has long been recognized for its extraordinary karyotypic diversity: the African pygmy mice. This survey involved 5 species, representing 10 highly diverse karyotypes with or without autosomal and sex-autosome robertsonian (Rb) fusions. The study revealed that in species with an ancestral-like karyotype (i.e., no fusions; Mus mattheyi and M. indutus), only terminal telomeres were observed, whereas in species experiencing intense chromosomal evolution (e.g., M. minutoides, M. musculoides), a large amplification of telomeric repeats was also identified in the pericentromeric region of acrocentrics and most metacentrics. We concluded that (i) the mechanism of Rb fusion in the African pygmy mice is different than the one highlighted in the house mouse; (ii) the intensity of the ITS hybridization signal could be a signature of the age of formation of the Rb fusion; (iii) the large amplification of pericentromeric telomeric sequences in acrocentrics may mediate the formation of Rb fusions, and (iv) the ITSs on the sex-autosome fusion Rb(X.1) may participate to the insulation buffer between the sexual and autosomal arms to prevent X inactivation from spreading and silencing autosomal genes and allow the independent regulation of replication timing of both segments.

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confidence: 99%

Extensive Amplification of Telomeric Repeats in the Karyotypically Highly Diverse African Pygmy Mice

Colomina¹,

Catalan²,

Britton‐Davidian³

et al. 2017

Cytogenet Genome Res

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“…rivulatus, reported also in representatives of different orders of fishes 61 including those of the subfamily Cichlinae within Cichliformes, 62 suggests a recent occurrence of chromosome rearrangement (fusions and inversions) during the karyotype diversification in cichlids. Indeed, telomeric repeats when present in sites other than those at the ends of the chromosomes, tend to shorten, to be lost over time, or to become inactive, 61,63,64 and the detection of residual sequences could be difficult 65 ; as a consequence, ITS could be considered not only a marker of chromosome rearrangements but also of their time of occurrence.…”

Section: Discussionmentioning

confidence: 99%

Molecular Analysis and Chromosome Mapping of Repetitive DNAs in the Green TerrorAndinoacara rivulatus(Cichlidae: Cichlasomatini)

et al. 2020

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Neotropical cichlids include hundreds of species whose taxonomy has benefited of molecular phylogeny and whose karyotype evolution has been related to the amount and distribution of different classes of repetitive sequences. This study provides the first integrative molecular (cytochrome c oxidase subunit 1 and 16S sequences) and cytogenetic analyses of wild samples of the green terror Andinoacara rivulatus, a cichlid naturally distributed in Ecuador and spread throughout the world as an aquarium pet. Molecular data revealed that sequences of green terror constitute a single monophyletic clade within the genus and allowed species attribution of uncertain samples previously cytogenetically analyzed. Chromosome number (2n = 48) conforms to the general trend observed within neotropical cichlids. However, mapping of different classes of repeated sequences (18S rDNA, 5S rDNA, U1 snDNA and telomeric) revealed the presence of features uncommon among representatives of these fishes, like multiple major rDNA sites, and suggested a recent occurrence of rearrangements (fusion/inversion) in two chromosome pairs.

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“…Embora em muitos casos cópias repetidas in tandem de sequências 5' TTAGGG3' possam ser evidenciadas por hibridação in situ como marcações muito tênues exclusivamente nos telômeros dos cromossomos (Meyne et al, 1990;Amaro-Ghilardi et al, 2008), ocasionalmente sequências desse tipo podem ser observadas em regiões intersticiais dos cromossomos de muitas espécies (revisão em Ruiz-Herrera et al, 2002;Ocalewicz, 2012).…”

Section: Características Citogenéticas De Dendropsophusunclassified

Estudo citogenético de espécies de Dendropsophus (Anura: Hylidae)

Rocha¹,

Morandini²

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Resumo O gênero Dendropsophus (Anura: Hylidae) é composto por 94 espécies neotropicais, das quais somente 31 foram estudadas citogeneticamente. Embora as espécies desse gênero apresentem o mesmo número cromossômico (2n=30), diferem quanto ao número fundamental e em relação à localização de NORs. Entretanto, a escassez de marcadores citogenéticos e o alto número de espécies com cariótipos ainda não descritos impedem inferências acerca dos possíveis eventos envolvidos na diferenciação cariotípica nesse gênero. Com o intuito de fornecer novos dados para a análise evolutiva cariotípica em Dendropsophus, no presente trabalho foram descritos os cariótipos de duas espécies do grupo de D. marmoratus, D. seniculus e D. soaresi, ampliada a caracterização dos cariótipos de D. decipiens, D. meridianus e descrito o de D. werneri, três espécies do grupo de D. microcephalus. Para a localização cromossômica do gene ribossomal 5S foram utilizadas sequências isoladas de D. soaresi. Também foram utilizadas sondas para verificar a localização cromossômica de sequências teloméricas em todas as espécies estudadas. Por fim, na tentativa de gerar sondas cromossômicas para futuros estudos dos cromossomos telocêntricos encontrados em Dendropsophus, experimentos de pintura cromossômica foram conduzidos com D. nanus e D. walfordi. Dendropsophus seniculus e D. soaresi apresentaram cariótipos muito semelhantes, com a NOR localizada no braço longo dos cromossomos do par 9. Tais cariótipos se assemelham também àqueles das outras três espécies já cariotipadas do grupo de D. marmoratus (D. marmoratus, D. melanargyreus e D. nahdereri), embora o cariótipo de D. nahdereri difira dos demais por apresentar a NOR no braço curto dos cromossomos do par 1. Dois tipos de sequências de DNAr 5S foram isolados de D. soaresi. A sequência identificada como do tipo I é composta por 512 pb, dos quais 390 pb pertencem à região não-transcritora (NTS); já a sequência do tipo II apresenta NTS com apenas 249 pb. A sequência nucleotídica do DNAr 5S do tipo I é idêntica a uma sequência encontrada no hilídeo Gastrotheca riobambae. Quando utilizado como sonda, esse segmento de DNAr 5S foi mapeado no braço longo dos cromossomos do par 2 de D. seniculus e D. soaresi. Sondas compostas por sequências teloméricas detectaram exclusivamente as regiões cromossômicas terminais de D. seniculus, assim como previamente observado em D. marmoratus e D. melanargyreus. Já em D. soaresi, as sondas teloméricas também resultaram em marcações centroméricas e pericentroméricas, exceto nos pares telocêntricos identificados como 5 e 6. Dentre as três espécies do grupo D. microcephalus aqui viii analisadas, D. decipiens, D. meridianus e D. werneri, algumas diferenças puderam ser notadas. Enquanto D. meridianus e D. werneri apresentaram apenas um par de cromossomos telocêntricos de tamanho mediano, no cariótipo de D. decipiens três pares de cromossomos telocêntricos de tamanho mediano puderam ser observados. D. berthalutzae, espécie considerada do mesmo clado de D. decipiens, também apresenta car...

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

Cited by 5 publications

References 115 publications

Extensive Amplification of Telomeric Repeats in the Karyotypically Highly Diverse African Pygmy Mice

Extensive Amplification of Telomeric Repeats in the Karyotypically Highly Diverse African Pygmy Mice

Molecular Analysis and Chromosome Mapping of Repetitive DNAs in the Green TerrorAndinoacara rivulatus(Cichlidae: Cichlasomatini)

Estudo citogenético de espécies de Dendropsophus (Anura: Hylidae)

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