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 Cytogenetically Elusive Sex Chromosomes in Scincoidean Lizards

2021 ◽  
Vol 22 (16) ◽  
pp. 8670
Author(s):  
Alexander Kostmann ◽  
Barbora Augstenová ◽  
Daniel Frynta ◽  
Lukáš Kratochvíl ◽  
Michail Rovatsos
Keyword(s):  
Sex Chromosomes ◽  
Chromosome Morphology ◽  
Comparative Genomic ◽  
Morphological Divergence ◽  
Telomeric Sequences ◽  
Molecular Cytogenetic ◽  
Interstitial Telomeric Sequences ◽  
Rdna Loci ◽  
Cytogenetic Methods

The lizards of the species-rich clade Scincoidea including cordylids, gerrhosaurids, skinks, and xantusiids, show an almost cosmopolitan geographical distribution and a remarkable ecological and morphological divergence. However, previous studies revealed limited variability in cytogenetic traits. The sex determination mode was revealed only in a handful of gerrhosaurid, skink, and xantusiid species, which demonstrated either ZZ/ZW or XX/XY sex chromosomes. In this study, we explored the karyotypes of six species of skinks, two species of cordylids, and one gerrhosaurid. We applied conventional and molecular cytogenetic methods, including C-banding, fluorescence in situ hybridization with probes specific for telomeric motifs and rDNA loci, and comparative genomic hybridization. The diploid chromosome numbers are rather conserved among these species, but the chromosome morphology, the presence of interstitial telomeric sequences, and the topology of rDNA loci vary significantly. Notably, XX/XY sex chromosomes were identified only in Tiliqua scincoides, where, in contrast to the X chromosome, the Y chromosome lacks accumulations of rDNA loci. We confirm that within the lizards of the scincoidean clade, sex chromosomes remained in a generally poor stage of differentiation.

scholarly journals Distribution of GC-rich heterochromatin and ribosomal genes in three fungus-farming ants (Myrmicinae, Attini, Attina): insights on chromosomal evolution

2021 ◽  
Vol 15 (4) ◽  
pp. 413-428
Author(s):  
Gisele Amaro Teixeira ◽  
Luísa Antônia Campos Barros ◽  
Hilton Jeferson Alves Cardoso de Aguiar ◽  
Denilce Meneses Lopes
Keyword(s):  
Chromosomal Rearrangements ◽  
Taxonomic Revision ◽  
Chromosomal Evolution ◽  
Ribosomal Genes ◽  
Common Origin ◽  
Rdna Site ◽  
Rdna Genes ◽  
Molecular Cytogenetic ◽  
Cytogenetic Data ◽  
Molecular Cytogenetic Techniques

Cytogenetic studies on fungus-farming ants have shown remarkable karyotype diversity, suggesting different chromosomal rearrangements involved in karyotype evolution in some genera. A notable cytogenetic characteristic in this ant group is the presence of GC-rich heterochromatin in the karyotypes of some ancient and derivative species. It was hypothesized that this GC-rich heterochromatin may have a common origin in fungus-farming ants, and the increase in species studied is important for understanding this question. In addition, many genera within the subtribe Attina have few or no cytogenetically studied species; therefore, the processes that shaped their chromosomal evolution remain obscure. Thus, in this study, we karyotyped, through classical and molecular cytogenetic techniques, the fungus-farming ants Cyphomyrmex transversus Emery, 1894, Sericomyrmex maravalhas Ješovnik et Schultz, 2017, and Mycetomoellerius relictus (Borgmeier, 1934), to provide insights into the chromosomal evolution in these genera and to investigate the presence the GC-rich heterochromatin in these species. Cyphomyrmex transversus (2n = 18, 10m + 2sm + 6a) and S. maravalhas (2n = 48, 28m + 20sm) showed karyotypes distinct from other species from their genera. Mycetomoellerius relictus (2n = 20, 20m) presented the same karyotype as the colonies previously studied. Notably, C. transversus presented the lowest chromosomal number for the genus and a distinct karyotype from the other two previously observed for this species, showing the existence of a possible species complex and the need for its taxonomic revision. Chromosomal banding data revealed GC-rich heterochromatin in all three species, which increased the number of genera with this characteristic, supporting the hypothesis of a common origin of GC-rich heterochromatin in Attina. Although a single chromosomal pair carries rDNA genes in all studied species, the positions of these rDNA clusters varied. The rDNA genes were located in the intrachromosomal region in C. transversus and M. relictus, and in the terminal region of S. maravalhas. The combination of our molecular cytogenetic data and observations from previous studies corroborates that a single rDNA site located in the intrachromosomal region is a plesiomorphic condition in Attina. In addition, cytogenetic data obtained suggest centric fission events in Sericomyrmex Mayr, 1865, and the occurrence of inversions as the origin of the location of the ribosomal genes in M. relictus and S. maravalhas. This study provides new insights into the chromosomal evolution of fungus-farming ants.

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.

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.

Comparative cytogenetics of four species of Thrichomys (Rodentia: Echimyidae)

Genome ◽  
2019 ◽  
Vol 62 (1) ◽  
pp. 31-41
Author(s):  
Naiara Pereira Araújo ◽  
Cibele Bonvicino ◽  
Marta Svartman
Keyword(s):  
Nucleolar Organizer ◽  
Interspecific Variation ◽  
Northeastern Brazil ◽  
Nucleolar Organizer Regions ◽  
Comparative Cytogenetics ◽  
Telomeric Sequences ◽  
Interstitial Telomeric Sequences ◽  
Robertsonian Rearrangements ◽  
Cytogenetic Analyses

Thrichomys Trouessart, 1880 is a genus of echimyid rodents endemic to South America, distributed from northeastern Brazil to Paraguay and Bolivia. Although all the recognized species of this genus have already been karyotyped, detailed comparative cytogenetic analyses have not been performed yet. We karyologically analyzed four species of Thrichomys from different Brazilian states. Our analyses included GTG- and CBG-banding, silver-staining of the nucleolar organizer regions (Ag-NORs), and fluorescent in situ hybridization (FISH) with telomeric and 45S rDNA probes. Comparative GTG-banding suggested that the interspecific variation may result from Robertsonian rearrangements, pericentric and paracentric inversions, centromere repositioning, and heterochromatin variation. FISH with a telomeric probe showed interspecies variation in interstitial telomeric sequences (ITs) distribution. Our results represent the most complete data on the cytogenetics of Thrichomys reported to date and give an insight into the chromosome evolution of this genus.

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.

Differentiation of Sex Chromosomes and Karyotype Characterisation in the Dragonsnake Xenodermus javanicus (Squamata: Xenodermatidae)

2015 ◽  
Vol 147 (1) ◽  
pp. 48-54 ◽  
Author(s):  
Michail Rovatsos ◽  
Martina Johnson Pokorná ◽  
Lukáš Kratochvíl
Keyword(s):  
Basic Principle ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Telomeric Sequences ◽  
Chromosomal Number ◽  
Interstitial Telomeric Sequences ◽  
The Family ◽  
First Time ◽  
Telomeric Probe

Highly differentiated heteromorphic ZZ/ZW sex chromosomes with a heterochromatic W are a basic principle among advanced snakes of the lineage Colubroidea, while other snake lineages generally lack these characteristics. For the first time, we cytogenetically examined the dragonsnake, Xenodermus javanicus, a member of the family Xenodermatidae, which is phylogenetically nested between snake lineages with and without differentiated sex chromosomes. Although most snakes have a karyotype with a stable chromosomal number of 2n = 36, the dragonsnake has an unusual, derived karyotype with 2n = 32 chromosomes. We found that heteromorphic ZZ/ZW sex chromosomes with a heterochromatic W are present in the dragonsnake, which suggests that the emergence of a highly differentiated W sex chromosome within snakes predates the split of Xenodermatidae and the clade including families Pareatidae, Viperidae, Homalopsidae, Lamprophiidae, Elapidae, and Colubridae. Although accumulations of interstitial telomeric sequences have not been previously reported in snakes, by using FISH with a telomeric probe we discovered them in 6 pairs of autosomes as well as in the W sex chromosome of the dragonsnake. Similarly to advanced snakes, the sex chromosomes of the dragonsnake have a significant accumulation of repeats containing a (GATA)n sequence. The results facilitate the dating of the differentiation of sex chromosomes within snakes back to the split between Xenodermatidae and other advanced snakes, i.e. around 40-75 mya.

scholarly journals Comparative cytogenetics of Serrasalmidae (Teleostei: Characiformes): The relationship between chromosomal evolution and molecular phylogenies

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0258003
Author(s):  
Ramon Marin Favarato ◽  
Leila Braga Ribeiro ◽  
Alber Campos ◽  
Jorge Ivan Rebelo Porto ◽  
Celeste Mutuko Nakayama ◽  
...  
Keyword(s):  
Chromosome Number ◽  
Chromosomal Rearrangements ◽  
5S Rdna ◽  
Chromosomal Evolution ◽  
Comparative Cytogenetics ◽  
Molecular Cytogenetic ◽  
The Family ◽  
Identification Of Species ◽  
Molecular Cytogenetic Techniques ◽  
The Relationship

Serrasalmidae has high morphological and chromosomal diversity. Based on molecular hypotheses, the family is currently divided into two subfamilies, Colossomatinae and Serrasalminae, with Serrasalminae composed of two tribes: Myleini (comprising most of pacus species) and Serrasalmini (represented by Metynnis, Catoprion, and remaining piranha’s genera). This study aimed to analyze species of the tribes Myleini (Myloplus asterias, M. lobatus, M. rubripinnis, M. schomburgki, and Tometes camunani) and Serrasalmini (Metynnis cuiaba, M. hypsauchen, and M. longipinnis) using classical and molecular cytogenetic techniques in order to understand the chromosomal evolution of the family. The four species of the genus Myloplus and T. camunani presented 2n = 58 chromosomes, while the species of Metynnis presented 2n = 62 chromosomes. The distribution of heterochromatin occurred predominantly in pericentromeric regions in all species. Tometes camunani and Myloplus spp. presented only one site with 5S rDNA. Multiple markers of 18S rDNA were observed in T. camunani, M. asterias, M. lobatus, M. rubripinnis, and M. schomburgkii. For Metynnis, however, synteny of the 18S and 5S rDNA was observed in the three species, in addition to an additional 5S marker in M. longipinnis. These data, when superimposed on the phylogeny of the family, suggest a tendency to increase the diploid chromosome number from 54 to 62 chromosomes, which occurred in a nonlinear manner and is the result of several chromosomal rearrangements. In addition, the different karyotype formulas and locations of ribosomal sequences can be used as cytotaxonomic markers and assist in the identification of species.

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