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

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.

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

Cytogenetic and Genome Research ◽

10.1159/000444602 ◽

2015 ◽

Vol 147 (4) ◽

pp. 247-252 ◽

Cited By ~ 5

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.

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

Cytogenetic and Genome Research ◽

10.1159/000478297 ◽

2017 ◽

Vol 152 (2) ◽

pp. 55-64 ◽

Cited By ~ 4

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.

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Interspecific cytogenetic relationships in three Acestrohynchus species (Acestrohynchinae, Characiformes) reveal the existence of possible cryptic species

Comparative Cytogenetics ◽

10.3897/compcytogen.v14i1.33483 ◽

2020 ◽

Vol 14 (1) ◽

pp. 27-42

Author(s):

Alber Sousa Campos ◽

Ramon Marin Favarato ◽

Eliana Feldberg

Keyword(s):

Chromosome Pair ◽

Organizer Region ◽

Nucleolus Organizer Region ◽

5S Rdna ◽

Nucleolus Organizer ◽

Telomeric Sequences ◽

Interstitial Telomeric Sequences ◽

Rdna Sites ◽

Species Specific

The karyotypes and chromosomal characteristics of three Acestrorhynchus Eigenmann et Kennedy, 1903 species were examined using conventional and molecular protocols. These species had invariably a diploid chromosome number 2n = 50. Acestrorhynchus falcatus (Block, 1794) and Acestrorhynchus falcirostris (Cuvier, 1819) had the karyotype composed of 16 metacentric (m) + 28 submetacentric (sm) + 6 subtelocentric (st) chromosomes while Acestrorhynchus microlepis (Schomburgk, 1841) had the karyotype composed of 14m+30sm+6st elements. In this species, differences of the conventional and molecular markers between the populations of Catalão Lake (AM) and of Apeu Stream (PA) were found. Thus the individuals of Pará (Apeu) were named Acestrorhynchus prope microlepis. The distribution of the constitutive heterochromatin blocks was species-specific, with C-positive bands in the centromeric and telomeric regions of a number of different chromosomes, as well as in interstitial sites and completely heterochromatic arms. The phenotypes of nucleolus organizer region (NOR) were simple, i. e. in a terminal position on the p arm of pair No. 23 except in A. microlepis, in which it was located on the q arm. Fluorescence in situ hybridization (FISH) revealed 18S rDNA sites on one chromosome pair in karyotype of A. falcirostris and A. prope microlepis (pair No. 23) and three pairs (Nos. 12, 23, 24) in A. falcatus and (Nos. 8, 23, 24) in A. microlepis; 5S rDNA sites were detected in one chromosome pair in all three species. The mapping of the telomeric sequences revealed terminal sequences in all the chromosomes, as well as the presence of interstitial telomeric sequences (ITSs) in a number of chromosome pairs. The cytogenetic data recorded in the present study indicate that A. prope microlepis may be an unnamed species.

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

Comparative Cytogenetics ◽

10.3897/compcytogen.v14i3.54422 ◽

2020 ◽

Vol 14 (3) ◽

pp. 417-435 ◽

Cited By ~ 1

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.

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Chromosomal painting of the sandpiper (Actitis macularius) detects several fissions for the Scolopacidae family (Charadriiformes)

BMC Ecology and Evolution ◽

10.1186/s12862-020-01737-x ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Melquizedec Luiz Silva Pinheiro ◽

Cleusa Yoshiko Nagamachi ◽

Talita Fernanda Augusto Ribas ◽

Cristovam Guerreiro Diniz ◽

Patricia Caroline Mary O´Brien ◽

...

Keyword(s):

Chromosome Painting ◽

Diploid Number ◽

Chromosomal Evolution ◽

Long Distance ◽

Chromosomal Painting ◽

Cytogenetic Studies ◽

Burhinus Oedicnemus ◽

Clear Idea ◽

First Time

Abstract Background The Scolopacidae family (Suborder Scolopaci, Charadriiformes) is composed of sandpipers and snipes; these birds are long-distance migrants that show great diversity in their behavior and habitat use. Cytogenetic studies in the Scolopacidae family show the highest diploid numbers for order Charadriiformes. This work analyzes for the first time the karyotype of Actitis macularius by classic cytogenetics and chromosome painting. Results The species has a diploid number of 92, composed mostly of telocentric pairs. This high 2n is greater than the proposed 80 for the avian ancestral putative karyotype (a common feature among Scolopaci), suggesting that fission rearrangements have formed smaller macrochromosomes and microchromosomes. Fluorescence in situ hybridization using Burhinus oedicnemus whole chromosome probes confirmed the fissions in pairs 1, 2, 3, 4 and 6 of macrochromosomes. Conclusion Comparative analysis with other species of Charadriiformes studied by chromosome painting together with the molecular phylogenies for the order allowed us to raise hypotheses about the chromosomal evolution in suborder Scolopaci. From this, we can establish a clear idea of how chromosomal evolution occurred in this suborder.

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Diversity and Karyotypic Evolution in the Genus Neacomys (Rodentia, Sigmodontinae)

Cytogenetic and Genome Research ◽

10.1159/000441173 ◽

2015 ◽

Vol 146 (4) ◽

pp. 296-305 ◽

Cited By ~ 9

Author(s):

Willam O. da Silva ◽

Julio C. Pieczarka ◽

Rogério V. Rossi ◽

Horacio Schneider ◽

Iracilda Sampaio ◽

...

Keyword(s):

Molecular Phylogeny ◽

Diploid Number ◽

Constitutive Heterochromatin ◽

Chromosomal Evolution ◽

The Other ◽

Karyotypic Evolution ◽

Drastic Reduction ◽

Ancestral Species ◽

Pericentric Inversions ◽

Amazonian Region

Neacomys (Sigmodontinae) comprises 8 species mainly found in the Amazonian region. We describe 5 new karyotypes from Brazilian Amazonia: 2 cytotypes for N. paracou (2n = 56/FNa = 62-66), 1 for N. dubosti (2n = 64/FNa = 68), and 2 for Neacomys sp. (2n = 58/FNa = 64-70), with differences in the 18S rDNA. Telomeric probes did not show ITS. We provide a phylogeny using Cytb, and the analysis suggests that 2n = 56 with a high FNa is ancestral for the genus, as found in N. paracou, being retained by the ancestral forms of the other species, with an increase in 2n occurring independently in N. spinosus and N. dubosti. Alternatively, an increase in 2n may have occurred in the ancestral taxon of the other species, followed by independent 2n-reduction events in Neacomys sp. and in the ancestral species of N. tenuipes, N. guianae, N. musseri, and N. minutus. Finally, a drastic reduction event in the diploid number occurred in the ancestral species of N. musseri and N. minutus which exhibit the lowest 2n of the genus. The karyotypic variations found in both intra- and interspecific samples, associated with the molecular phylogeny, suggest a chromosomal evolution with amplification/deletion of constitutive heterochromatin and rearrangements including fusions, fissions, and pericentric inversions.

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