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

2017 ◽  
Vol 152 (2) ◽  
pp. 55-64 ◽  
Author(s):  
Victor Colomina ◽  
Josette Catalan ◽  
Janice Britton-Davidian ◽  
Frédéric Veyrunes
Keyword(s):  
Mammalian Species ◽  
Chromosomal Rearrangements ◽  
Replication Timing ◽  
Pericentromeric Region ◽  
Chromosomal Evolution ◽  
Telomeric Repeats ◽  
Telomeric Sequences ◽  
Interstitial Telomeric Sequences ◽  
Karyotypic Diversity ◽  
The One

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.

Distribution of Interstitial Telomeric Sequences in Primates and the Pygmy Tree Shrew (Scandentia)

2017 ◽  
Vol 151 (3) ◽  
pp. 141-150 ◽  
Author(s):  
Sofia Mazzoleni ◽  
Odessa Schillaci ◽  
Luca Sineo ◽  
Francesca Dumas
Keyword(s):  
Dna Sequences ◽  
Tree Shrew ◽  
Chromosomal Rearrangements ◽  
Primate Species ◽  
Telomeric Dna ◽  
Erythrocebus Patas ◽  
Telomeric Sequences ◽  
Interstitial Telomeric Sequences ◽  
Cercopithecus Petaurista ◽  
Almost All

It has been hypothesized that interstitial telomeric sequences (ITSs), i.e., repeated telomeric DNA sequences found at intrachromosomal sites in many vertebrates, could be correlated to chromosomal rearrangements and plasticity. To test this hypothesis, we hybridized a telomeric PNA probe through FISH on representative species of 2 primate infraorders, Strepsirrhini (Lemur catta, Otolemur garnettii, Nycticebus coucang) and Catarrhini (Erythrocebus patas, Cercopithecus petaurista, Chlorocebus aethiops, Colobus guereza), as well as on 1 species of the order Scandentia, Tupaia minor, used as an outgroup for primates in phylogenetic reconstructions. In almost all primate species analyzed, we found a telomeric pattern only. In Tupaia, the hybridization revealed many bright ITSs on at least 11 chromosome pairs, both biarmed and acrocentric. These ITS signals in Tupaia correspond to fusion points of ancestral human syntenic associations, but are also present in other chromosomes showing synteny to only a single human chromosome. This distribution pattern was compared to that of the heterochromatin regions detected through sequential C-banding performed after FISH. Our results in the analyzed species, compared with literature data on ITSs in primates, allowed us to discuss different mechanisms responsible for the origin and distribution of ITSs, supporting the correlation between rearrangements and ITSs.

scholarly journals At the Beginning of the End and in the Middle of the Beginning: Structure and Maintenance of Telomeric DNA Repeats and Interstitial Telomeric Sequences

Genes ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 118 ◽  
Author(s):  
Anna Y. Aksenova ◽  
Sergei M. Mirkin
Keyword(s):  
Genome Stability ◽  
Dynamic Properties ◽  
Chromosomal Rearrangements ◽  
Dna Repeats ◽  
Telomeric Dna ◽  
Telomeric Sequences ◽  
Gross Chromosomal Rearrangements ◽  
Interstitial Telomeric Sequences ◽  
Chromosomal Fragility ◽  
Living Organisms

Tandem DNA repeats derived from the ancestral (TTAGGG)n run were first detected at chromosome ends of the majority of living organisms, hence the name telomeric DNA repeats. Subsequently, it has become clear that telomeric motifs are also present within chromosomes, and they were suitably called interstitial telomeric sequences (ITSs). It is well known that telomeric DNA repeats play a key role in chromosome stability, preventing end-to-end fusions and precluding the recurrent DNA loss during replication. Recent data suggest that ITSs are also important genomic elements as they confer its karyotype plasticity. In fact, ITSs appeared to be among the most unstable microsatellite sequences as they are highly length polymorphic and can trigger chromosomal fragility and gross chromosomal rearrangements. Importantly, mechanisms responsible for their instability appear to be similar to the mechanisms that maintain the length of genuine telomeres. This review compares the mechanisms of maintenance and dynamic properties of telomeric repeats and ITSs and discusses the implications of these dynamics on genome stability.

Distribution of Telomeric Sequences (TTAGGG)n in Rearranged Chromosomes of Phyllotine Rodents (Cricetidae, Sigmodontinae)

2015 ◽  
Vol 147 (4) ◽  
pp. 247-252 ◽  
Author(s):  
Cecilia Lanzone ◽  
Carolina Labaroni ◽  
Natalia Suárez ◽  
Daniela Rodríguez ◽  
Macarena L. Herrera ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
Chromosomal Evolution ◽  
Robertsonian Translocations ◽  
Telomeric Sequences ◽  
Molecular Cytogenetic ◽  
Interstitial Telomeric Sequences ◽  
Robertsonian Rearrangements ◽  
Recent Origin ◽  
Chromosome Fusions ◽  
Molecular Cytogenetic Techniques

Phyllotines are sigmodontine rodents endemic to South America with broad genetic variability, Robertsonian polymorphisms being the most frequent. Moreover, this taxon includes a species with multiple sex chromosomes, which is infrequent in mammals. However, molecular cytogenetic techniques have never been applied to phyllotines to elucidate their karyotypic evolution. We studied the chromosomes of 4 phyllotine species using FISH with a pantelomeric probe (TTAGGG)n. Graomys griseoflavus, Eligmodontia puerulus, and E. morgani are polymorphic for Robertsonian translocations, whereas Salinomys delicatus possesses XX/ XY1Y2 sex chromosomes. Telomeric signals were detected at both ends of all chromosomes of the studied species. In S. delicatus interstitial telomeric sequences (ITS) were observed in the 3 major chromosome pairs, which are equidistant from one of the telomeres in these chromosomes. These results suggest that ITS are important in the reshuffling of the highly derived karyotype of S. delicatus. Considering the phylogeny of phyllotines, the Robertsonian rearrangements of G. griseoflavus, E. puerulus, and E. morgani possibly represent chromosome fusions which have occurred independently. The pericentromeric regions of the biarmed chromosomes of these species do not contain telomeric sequences characteristic for strict fusions of recent origin, suggesting a common pattern of telomeric repeat loss during chromosomal evolution of these rodents.

scholarly journals Chromosome spreading of the (TTAGGG)n repeats in the Pipa carvalhoi Miranda-Ribeiro, 1937 (Pipidae, Anura) karyotype

2019 ◽  
Vol 13 (3) ◽  
pp. 297-309 ◽  
Author(s):  
Michelle Louise Zattera ◽  
Luana Lima ◽  
Iraine Duarte ◽  
Deborah Yasmin de Sousa ◽  
Olívia Gabriela dos Santos Araújo ◽  
...  
Keyword(s):  
Chromosome Pair ◽  
Diploid Number ◽  
Centromeric Region ◽  
Chromosomal Evolution ◽  
Unique Combination ◽  
Significant Component ◽  
Aquatic Life ◽  
Telomeric Sequences ◽  
Interstitial Telomeric Sequences ◽  
Chromosome Spreading

Pipidae is a clade of Anura that diverged relatively early from other frogs in the phylogeny of the group. Pipids have a unique combination of morphological features, some of which appear to represent a mix of adaptations to aquatic life and plesiomorphic characters of Anura. The present study describes the karyotype of Pipa carvalhoi Miranda-Ribeiro, 1937, including morphology, heterochromatin distribution, and location of the NOR site. The diploid number of P. carvalhoi is 2n=20, including three metacentric pairs (1, 4, 8), two submetacentric (2 and 7), three subtelocentric (3, 5, 6), and two telocentric pairs (9 and 10). C-banding detected centromeric blocks of heterochromatin in all chromosome pairs and the NOR detected in chromosome pair 9, as confirmed by FISH using the rDNA 28S probe. The telomeric probes indicated the presence of interstitial telomeric sequences (ITSs), primarily in the centromeric region of the chromosomes, frequently associated with heterochromatin, suggesting that these repeats are a significant component of this region. The findings of the present study provide important insights for the understanding of the mechanisms of chromosomal evolution in the genus Pipa, and the diversification of the Pipidae as a whole.

Pseudodicentric Chromosome Originating from Autosomes 9 and 21 in a Male Patient with Oligozoospermia

2019 ◽  
Vol 159 (4) ◽  
pp. 201-207
Author(s):  
Marion Beaumont ◽  
Elena J. Tucker ◽  
Laura Mary ◽  
Erika Launay ◽  
Yann Lurton ◽  
...  
Keyword(s):  
Male Infertility ◽  
Genetic Factors ◽  
Chromosomal Rearrangements ◽  
Chromosomal Anomalies ◽  
Derivative Chromosome ◽  
Telomeric Sequences ◽  
Dicentric Chromosomes ◽  
Interstitial Telomeric Sequences ◽  
Cytogenetic Analyses ◽  
Reproductive Phenotype

Genetic factors are responsible for 15% of male infertility conditions. Numerical and structural chromosomal anomalies (related to the Y chromosome or to the autosomes) are validated genetic factors leading to spermatogenic quantitative defects with a frequency depending on the severity of the phenotype. The most frequent structural chromosomal rearrangements of autosomes are translocations and inversions, whereas dicentric chromosomes involving autosomes are rare. We report a man bearing a pseudodicentric chromosome (9;21) and presenting with oligozoospermia. Extensive cytogenetic analyses were necessary to determine the precise nature of the derivative chromosome and to discount the presence of interstitial telomeric sequences. Defects in spermatogenesis and abnormal segregation at meiosis for existing spermatozoa are proposed and are the likely cause of the reproductive phenotype of the patient.

scholarly journals Extensive Sex Chromosome Polymorphism of Microtus thomasi/Microtus atticus Species Complex Associated with Cryptic Chromosomal Rearrangements and Independent Accumulation of Heterochromatin

2017 ◽  
Vol 151 (4) ◽  
pp. 198-207 ◽  
Author(s):  
Michail T. Rovatsos ◽  
Juan A. Marchal ◽  
Ismael Romero-Fernández ◽  
Maria Arroyo ◽  
Eva B. Athanasopoulou ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
Dna Sequences ◽  
Sex Chromosome ◽  
Chromosomal Rearrangements ◽  
Chromosomal Evolution ◽  
Chromosome Polymorphism ◽  
Random Drift ◽  
X Chromosomes ◽  
Karyotypic Diversity ◽  
Comparative Painting

The sibling species Microtus thomasi and M. atticus represent probably the highest karyotypic diversity within the genus Microtus and are an interesting model for chromosomal evolution studies. In addition to variation in autosomes, they show a high intraspecific variation in the size and morphology of both sex chromosomes. We analyzed individuals with different sex chromosome constitutions using 3 painting probes, 2 from Y chromosome variants and 1 from the small arm of the submetacentric X chromosome. Our comparative painting approach uncovered 12 variants of Y and 14 variants of X chromosomes, which demonstrates that the polymorphism of sex chromosomes is substantially larger than previously reported. We suggest that 2 main processes are responsible for this sex chromosome polymorphism: change of morphology from acrocentric to submetacentric or metacentric chromosomes and increase in size due to accumulation of repetitive DNA sequences, generating heterochromatic blocks. Strong genetic drift in small and fragmented populations of these 2 species could be related to the origin and maintenance of the large polymorphism of sex chromosomes. We proposed that a similar polymorphism variation combined with random drift fixing the biggest sex chromosomes could have occurred in the origin of some of the actual Microtus species with giant sex chromosomes.

scholarly journals Ancestral reconstruction of sunflower karyotypes reveals non-random chromosomal evolution

2019 ◽  
Author(s):  
Kate L. Ostevik ◽  
Kieran Samuk ◽  
Loren H. Rieseberg
Keyword(s):  
Ad Hoc ◽  
Hybrid Sterility ◽  
Chromosomal Rearrangements ◽  
Chromosomal Evolution ◽  
R Package ◽  
High Density ◽  
Genetic Maps ◽  
High Rate ◽  
Ancestral Reconstruction ◽  
Karyotypic Diversity

AbstractMapping the chromosomal rearrangements between species can inform our understanding of genome evolution, reproductive isolation, and speciation. Here we present a novel algorithm for identifying regions of synteny in pairs of genetic maps, which is implemented in the accompanying R package, syntR. The syntR algorithm performs as well as previous ad-hoc methods while being systematic, repeatable, and is applicable to mapping chromosomal rearrangements in any group of species. In addition, we present a systematic survey of chromosomal rearrangements in the annual sunflowers, which is a group known for extreme karyotypic diversity. We build high-density genetic maps for two subspecies of the prairie sunflower, Helianthus petiolaris ssp. petiolaris and H. petiolaris ssp. fallax.Using syntR, and we identify blocks of synteny between these two subspecies and previously published high-density genetic maps. We reconstruct ancestral karyotypes for annual sunflowers using those synteny blocks and conservatively estimate that there have been 7.9 chromosomal rearrangements per million years – a high rate of chromosomal evolution. Although the rate of inversion is even higher than the rate of translocation in this group, we further find that every extant karyotype is distinguished by between 1 and 3 translocations involving only 8 of the 17 chromosomes. This non-random exchange suggests that specific chromosomes are prone to translocation and may thus contribute disproportionately to widespread hybrid sterility in sunflowers. These data deepen our understanding of chromosome evolution and confirm that Helianthus has an exceptional rate of chromosomal rearrangement that may facilitate similarly rapid diversification.

scholarly journals Ancestral Reconstruction of Karyotypes Reveals an Exceptional Rate of Nonrandom Chromosomal Evolution in Sunflower

Genetics ◽  
2020 ◽  
Vol 214 (4) ◽  
pp. 1031-1045 ◽  
Author(s):  
Kate L. Ostevik ◽  
Kieran Samuk ◽  
Loren H. Rieseberg
Keyword(s):  
Ad Hoc ◽  
Hybrid Sterility ◽  
Chromosomal Rearrangements ◽  
Chromosomal Evolution ◽  
R Package ◽  
High Density ◽  
Genetic Maps ◽  
High Rate ◽  
Ancestral Reconstruction ◽  
Karyotypic Diversity

Mapping the chromosomal rearrangements between species can inform our understanding of genome evolution, reproductive isolation, and speciation. Here, we present a novel algorithm for identifying regions of synteny in pairs of genetic maps, which is implemented in the accompanying R package syntR. The syntR algorithm performs as well as previous ad hoc methods while being systematic, repeatable, and applicable to mapping chromosomal rearrangements in any group of species. In addition, we present a systematic survey of chromosomal rearrangements in the annual sunflowers, which is a group known for extreme karyotypic diversity. We build high-density genetic maps for two subspecies of the prairie sunflower, Helianthus petiolaris ssp. petiolaris and H. petiolaris ssp. fallax. Using syntR, we identify blocks of synteny between these two subspecies and previously published high-density genetic maps. We reconstruct ancestral karyotypes for annual sunflowers using those synteny blocks and conservatively estimate that there have been 7.9 chromosomal rearrangements per million years, a high rate of chromosomal evolution. Although the rate of inversion is even higher than the rate of translocation in this group, we further find that every extant karyotype is distinguished by between one and three translocations involving only 8 of the 17 chromosomes. This nonrandom exchange suggests that specific chromosomes are prone to translocation and may thus contribute disproportionately to widespread hybrid sterility in sunflowers. These data deepen our understanding of chromosome evolution and confirm that Helianthus has an exceptional rate of chromosomal rearrangement that may facilitate similarly rapid diversification.

scholarly journals Rapid chromosomal evolution in the bush-cricket Gonatoxia helleri Hemp, 2016 (Orthoptera, Phaneropterinae)

2020 ◽  
Vol 14 (3) ◽  
pp. 417-435 ◽  
Author(s):  
Elżbieta Warchałowska-Śliwa ◽  
Beata Grzywacz ◽  
Anna Maryańska-Nadachowska ◽  
Klaus-Gerhard Heller ◽  
Claudia Hemp
Keyword(s):  
Chromosome Number ◽  
18S Rdna ◽  
Chromosomal Polymorphism ◽  
Chromosomal Evolution ◽  
Chromosome Morphology ◽  
Telomeric Sequences ◽  
C Banding ◽  
Interstitial Telomeric Sequences ◽  
Rdna Loci ◽  
Bush Crickets

Gonatoxia helleri Hemp, 2016 is one of the most widespread bush-crickets of the genus Gonatoxia Karsch, 1889 in East Africa. This species with seven large chromosomes (2n♂ = 7) differs from other representatives of the genus Gonatoxia drastically by its reduced chromosome number, the asymmetrical karyotype including karyomorphs rarely found in tettigoniids, as well as in irregularities in the course of meiosis. To better understand the origin of such an exceptional karyotype, chromosomes of 29 specimens from four populations/localities were studied using classical techniques, such as C-banding, silver impregnation, fluorochrome double staining and fluorescence in situ hybridization (FISH) technique with 18S rDNA and (TTAGG)n telomeric probes. FISH showed many 18S rDNA loci as well as interstitial telomeric sequences, where chromosome morphology varied in these components in terms of quantity and distribution. The 18S rDNA loci coincided with active NORs and C-banding patterns. We suggest that a combination of Robertsonian rearrangements and/or multiple common tandem fusions involving the same chromosomes contributed to the formation of this karyotype/karyomorphs. The results are the first step towards a better understanding of chromosomal reorganization and evolution within the genus Gonatoxia. Low chromosome number, together with the incidence of chromosomal polymorphism that is higher in G. helleri than previously reported in bush-crickets, implies that this species can be a valuable new model for cytogenetic and speciation studies. Our findings suggest that chromosomal translocations lead to diversification and speciation in this species and could be the driving force of adaptive radiation.

scholarly journals Comparative FISH analysis of Senna tora tandem repeats revealed insights into the chromosome dynamics in Senna

2021 ◽  
Vol 43 (3) ◽  
pp. 237-249 ◽  
Author(s):  
Thanh Dat Ta ◽  
Nomar Espinosa Waminal ◽  
Thi Hong Nguyen ◽  
Remnyl Joyce Pellerin ◽  
Hyun Hee Kim
Keyword(s):  
Tandem Repeats ◽  
Chromosomal Rearrangements ◽  
Organizer Region ◽  
Nucleolar Organizer Region ◽  
Nucleolar Organizer ◽  
Pericentromeric Region ◽  
Its2 Sequence ◽  
Fish Analysis ◽  
Chromosomal Distribution ◽  
Chromosome Dynamics

Abstract Background DNA tandem repeats (TRs) are often abundant and occupy discrete regions in eukaryotic genomes. These TRs often cause or generate chromosomal rearrangements, which, in turn, drive chromosome evolution and speciation. Tracing the chromosomal distribution of TRs could therefore provide insights into the chromosome dynamics and speciation among closely related taxa. The basic chromosome number in the genus Senna is 2n = 28, but dysploid species like Senna tora have also been observed. Objective To understand the dynamics of these TRs and their impact on S. tora dysploidization. Methods We performed a comparative fluorescence in situ hybridization (FISH) analysis among nine closely related Senna species and compared the chromosomal distribution of these repeats from a cytotaxonomic perspective by using the ITS1-5.8S-ITS2 sequence to infer phylogenetic relationships. Results Of the nine S. tora TRs, two did not show any FISH signal whereas seven TRs showed similar and contrasting patterns to other Senna species. StoTR01_86, which was localized in the pericentromeric regions in all S. tora, but not at the nucleolar organizer region (NOR) site, was colocalized at the NOR site in all species except in S. siamea. StoTR02_7_tel was mostly localized at chromosome termini, but some species had an interstitial telomeric repeat in a few chromosomes. StoTR05_180 was distributed in the subtelomeric region in most species and was highly amplified in the pericentromeric region in some species. StoTR06_159 was either absent or colocalized in the NOR site in some species, and StoIGS_463, which was localized at the NOR site in S. tora, was either absent or localized at the subtelomeric or pericentromeric regions in other species. Conclusions These data suggest that TRs play important roles in S. tora dysploidy and suggest the involvement of 45S rDNA intergenic spacers in “carrying” repeats during genome reshuffling.

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