Chromosomal Instability and Origin of B Chromosomes in the Amazonian Glass Tetra Moenkhausia oligolepis (Günther, 1864) (Characiformes, Characidae)

2021 ◽  
pp. 249-256
Author(s):  
Luana Pereira dos Santos ◽  
Carine M. Francisco ◽  
Edimar O. Campos Júnior ◽  
Jonathan P. Castro ◽  
Ricardo Utsunomia ◽  
...  
Keyword(s):  
Chromosomal Instability ◽  
Diploid Number ◽  
Karyotype Analysis ◽  
Pericentromeric Region ◽  
Nucleolus Organizer ◽  
B Chromosomes ◽  
Interindividual Variation ◽  
Nucleolus Organizer Regions ◽  
Karyotypic Formula ◽  
Whole Chromosome Painting

B chromosomes occur in different species of the small characid fishes of the genus <i>Moenkhausia.</i> These supernumerary elements, that do not recombine with chromosomes of the standard A complement and follow their own evolutionary mechanism vary in number, morphology, and distribution. Here, we show karyotypic data of individuals of 2 populations of <i>Moenkhausia oligolepis</i> of the Brazilian Amazon (Pedro Correia and Taboquinha streams, Tocantins river basin), both with a diploid number of 50 chromosomes and karyotypic formula of 10m + 32sm + 8a. In addition to the normal complement, we also observed the occurrence of B chromosomes in the 2 populations with intra- and interindividual variation ranging from 0 to 10 Bs, independent of sex. The C-banding pattern evidenced heterochromatic blocks located mainly in the pericentromeric region of the chromosomes, while the B chromosomes appeared euchromatic. Silver-stained nucleolus organizer regions were identified in multiples sites, and some of these blocks were positive when stained with chromomycin A<sub>3.</sub> The karyotype analysis and the application of whole-chromosome painting in populations of <i>M. oligolepis</i> reinforce the conservation of the basal diploid number for the genus, as well as the evolutionary tendency in these fishes to carry B chromosomes. Both populations turned out to be in different stages of stability and expansion of their B chromosomes. We further suggest that the origin of these chromosomes is due to the formation of isochromosomes. Here, we identified a pair of complement A chromosomes involved in this process.

scholarly journals Comparative analysis based on replication banding reveals the mechanism responsible for the difference in the karyotype constitution of treefrogs Ololygon and Scinax (Arboranae, Hylidae, Scinaxinae)

2017 ◽  
Vol 11 (2) ◽  
pp. 267-283 ◽  
Author(s):  
Simone Lilian Gruber ◽  
Gabriela Isabela Gomes de Oliveira ◽  
Ana Paula Zampieri Silva ◽  
Hideki Narimatsu ◽  
Célio Fernando Baptista Haddad ◽  
...  
Keyword(s):  
Chromosome Banding ◽  
Diploid Number ◽  
Nucleolus Organizer ◽  
Replication Banding ◽  
Nucleolus Organizer Regions ◽  
The Family ◽  
The Difference ◽  
Size And Morphology ◽  
Phylogenetic Revision ◽  
Dna Incorporation

According to the recent taxonomic and phylogenetic revision of the family Hylidae, species of the former Scinaxcatharinae (Boulenger, 1888) clade were included in the resurrected genus Ololygon Fitzinger, 1843, while species of the Scinaxruber (Laurenti, 1768) clade were mostly included in the genus Scinax Wagler, 1830, and two were allocated to the newly created genus JulianusDuellman et al., 2016. Although all the species of the former Scinax genus shared a diploid number of 2n = 24 and the same fundamental number of chromosome arms of FN = 48, two karyotypic constitutions were unequivocally recognized, related mainly to the distinct size and morphology of the first two chromosome pairs. Some possible mechanisms for these differences had been suggested, but without any experimental evidence. In this paper, a comparison was carried out based on replication chromosome banding, obtained after DNA incorporation of 5-bromodeoxiuridine in chromosomes of Ololygon and Scinax. The obtained results revealed that the loss of repetitive segments in chromosome pairs 1 and 2 was the mechanism responsible for karyotype difference. The distinct localization of the nucleolus organizer regions in the species of both genera also differentiates the two karyotypic constitutions.

scholarly journals Karyotype variability in neotropical catfishes of the family Pimelodidae (Teleostei: Siluriformes)

2011 ◽  
Vol 9 (1) ◽  
pp. 97-105 ◽  
Author(s):  
Américo Moraes Neto ◽  
Maelin da Silva ◽  
Daniele Aparecida Matoso ◽  
Marcelo Ricardo Vicari ◽  
Mara Cristina de Almeida ◽  
...  
Keyword(s):  
Fluorescent In Situ Hybridization ◽  
Diploid Number ◽  
Molecular Cytogenetics ◽  
Ribosomal Genes ◽  
Nucleolus Organizer ◽  
Nucleolus Organizer Regions ◽  
Karyotype Variability ◽  
Interspecific Variations ◽  
The Family

Karyotypic data are presented for four species of fish belonging to the Pimelodidae family. These species show a conserved diploid number, 2n = 56 chromosomes, with different karyotypic formulae. The analyzed species showed little amount of heterochromatin located preferentially in the centromeric and telomeric regions of some chromosomes. The nucleolus organizer regions activity (Ag-NORs) and the chromosomal location of ribosomal genes by fluorescent in situ hybridization (FISH), with 18S and 5S probes, showing only one chromosome pair marked bearer of ribosomal genes, the only exception was Pimelodus britskii that presented multiple NORs and syntenic location of the 18S and 5S probes. Non-Robertsonian events, as pericentric inversion and NORs duplication are requested to explain the karyotype diversification in Pseudoplatystoma from the rio Paraguay (MS), Pimelodus from the rio Iguaçu (PR), Sorubim from the rio Paraguay (MS) and Steindachneridion from the rio Paraíba do Sul (SP). The obtained data for the karyotype macrostructure of these species corroborates a conserved pattern observed in Pimelodidae. On the other hand, interspecific variations detected by molecular cytogenetics markers made possible cytotaxonomic inferences and differentiation of the species here analyzed.

Cytogenetic Analysis of Panaqolus tankei Cramer & Sousa, 2016 (Siluriformes, Loricariidae), an Ornamental Fish Endemic to Xingu River, Brazil

2021 ◽  
pp. 1-8
Author(s):  
Alex M.V. Ferreira ◽  
Patrik F. Viana ◽  
Jansen Zuanon ◽  
Tariq Ezaz ◽  
Marcelo B. Cioffi ◽  
...  
Keyword(s):  
18S Rdna ◽  
Diploid Number ◽  
5S Rdna ◽  
Sister Group ◽  
Nucleolus Organizer ◽  
Comparative Genomic ◽  
Nucleolus Organizer Regions ◽  
Chromosomal Changes ◽  
The Impact

Despite conservation of the diploid number, a huge diversity in karyotype formulae is found in the Ancistrini tribe (Loricariidae, Hypostominae). However, the lack of cytogenetic data for many groups impairs a comprehensive understanding of the chromosomal relationships and the impact of chromosomal changes on their evolutionary history. Here, we present for the first time the karyotype of Panaqolus tankei Cramer &amp; Sousa, 2016. We focused on the chromosomal characterization, using conventional and molecular cytogenetic techniques to unravel the evolutionary trends of this tribe. P. tankei, as most species of its sister group Pterygoplichthini, also possessess a conserved diploid number of 52 chromosomes. We observed heterochromatin regions in the centromeres of many chromosomes; pairs 5 and 6 presented interstitial heterochromatin regions, whereas pairs 23 and 24 showed extensive heterochromatin regions in their q arms. In situ localization of 18S rDNA showed hybridization signals correlating with the nucleolus organizer regions, which are located in the q arms of pair 5. However, the 5S rDNA was detected in the centromeric and terminal regions of the q arms of pair 8. (TTAGGG)n hybridized only in the terminal regions of all chromosomes. Microsatellite in situ localization showed divergent patterns, (GA)15 repeated sequences were restricted to the terminal regions of some chromosomes, whereas (AC)15 and (GT)15 showed a scattered hybridization pattern throughout the genome. Intraspecific comparative genomic hybridization was performed on the chromosomes of P. tankei to verify the existence of sex-specific regions. The results revealed only a limited number of overlapping hybridization signals, coinciding with the heterochromatin in centromeric regions without any sex-specific signals in both males and females. Our study provides a karyotype description of P. tankei, highlighting extensive differences in the karyotype formula, the heterochromatin regions, and sites of 5S and 18S rDNA, as compared with data available for the genus.

scholarly journals Comparative analysis based on replication banding reveals the mechanism responsible for the difference in the karyotype constitution of treefrogs Ololygon and Scinax (Arboranae, Hylidae, Scinaxinae)

2017 ◽  
Vol 11 (2) ◽  
pp. 267-283
Author(s):  
Simone Lilian Gruber ◽  
Gabriela Isabela Gomes de Oliveira ◽  
Ana Paula Zampieri Silva ◽  
Hideki Narimatsu ◽  
Célio Fernando Baptista Haddad ◽  
...  
Keyword(s):  
Chromosome Banding ◽  
Diploid Number ◽  
Nucleolus Organizer ◽  
Replication Banding ◽  
Nucleolus Organizer Regions ◽  
The Family ◽  
The Difference ◽  
Size And Morphology ◽  
Phylogenetic Revision ◽  
Dna Incorporation

According to the recent taxonomic and phylogenetic revision of the family Hylidae, species of the former Scinaxcatharinae (Boulenger, 1888) clade were included in the resurrected genus Ololygon Fitzinger, 1843, while species of the Scinaxruber (Laurenti, 1768) clade were mostly included in the genus Scinax Wagler, 1830, and two were allocated to the newly created genus JulianusDuellman et al., 2016. Although all the species of the former Scinax genus shared a diploid number of 2n = 24 and the same fundamental number of chromosome arms of FN = 48, two karyotypic constitutions were unequivocally recognized, related mainly to the distinct size and morphology of the first two chromosome pairs. Some possible mechanisms for these differences had been suggested, but without any experimental evidence. In this paper, a comparison was carried out based on replication chromosome banding, obtained after DNA incorporation of 5-bromodeoxiuridine in chromosomes of Ololygon and Scinax. The obtained results revealed that the loss of repetitive segments in chromosome pairs 1 and 2 was the mechanism responsible for karyotype difference. The distinct localization of the nucleolus organizer regions in the species of both genera also differentiates the two karyotypic constitutions.

scholarly journals IDENTIFIKASI KROMOSOM HOMOLOG MELALUI DETEKSI NUCLEOLUS ORGANIZER REGIONS DENGAN PEWARNAAN AgNO3 PADA TANAMAN BAWANG MERAH - IN PRESS -

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Andin Puspita ◽  
Agus Budi Setiawan ◽  
Aziz Purwantoro ◽  
Endang Sulistyaningsih
Keyword(s):  
Chromosome Number ◽  
Chromosome Pair ◽  
Karyotype Analysis ◽  
Standard Procedure ◽  
Nucleolus Organizer ◽  
Specific Probe ◽  
Homologous Chromosomes ◽  
Nucleolus Organizer Regions ◽  
Carnoy’S Solution ◽  
Precise Identification

Generally, the standard procedure for karyotype analysis of shallot is sorted by chromosome sizes. Therefore, the identification of homologous chromosomes is difficult without using a specific probe. Nucleolus Organizing Regions (NORs) can be used as a probe for precise identification of homologous chromosomes. However, the use of NORs for plant karyotyping in Indonesia is poorly investigated. In this study, shallot chromosomes were prepared using modified Carnoy’s solution II, fixed in Carnoy’s solution, and stained by using aceto-carmine and AgNO3 for detecting NORs. Chromosome images were analyzed by CHIAS IV. One locus NOR bearing chromosome pair was detected at metaphase and interphase, and it was located at short arms of subtelomeric chromosome number 6. NORs can be used as a probe for precise identification of homologous chromosomes in shallot. Therefore, this technique has the potential to be applied on species closely related to shallot and on other plant species.Keywords: AgNO3, chromosome condensation, NORs, shallot chromosome, shallot karyotype ABSTRAKProsedur kariotipe untuk bawang merah umumnya masih disusun berdasarkan ukuran kromosom, sehingga diperlukan suatu penanda yang dapat mengidentifikasi kromosom homolog secara presisi. Identifikasi kromosom homolog secara presisi menggunakan suatu penanda, khususnya deteksi Nucleolus Organizing Regions (NORs), yang di Indonesia masih jarang dilakukan. Penelitian ini bertujuan untuk membuat kariotipe dan mengidentifikasi kromosom homolog bawang merah melalui deteksi NORs menggunakan metode pewarnaan AgNO3. Proses fiksasi akar dilakukan dengan menggunakan modifikasi larutan Carnoy II, lalu difiksasi dengan larutan Carnoy, dan kromosom diwarnai dengan aceto-carmine dan larutan AgNO3 untuk mendeteksi NORs. Selanjutnya, citra kromosom dianalisis menggunakan CHIAS IV. Hasil penelitian menunjukkan bahwa terdapat sepasang NORs yang terdeteksi pada fase metafase dan interfase yang  terletak pada bagian lengan pendek di kromosom subtelosentrik nomor 6. Hasil dari penelitian ini dapat dijadikan sebagai dasar di bidang sitogenetika bawang merah untuk mengidentifikasi kromosom homolog secara presisi menggunakan penanda NOR. Oleh karenanya, teknik ini dapat diaplikasikan pada spesies yang berdekatan dengan bawang merah dan komoditas tanaman lainnya.Kata Kunci: AgNO3, kariotipe bawang, kondensasi kromosom, kromosom bawang, NORs

scholarly journals Diversification of the Balloon bushcrickets (Orthoptera, Hexacentrinae, Aerotegmina) in the East African mountains

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Beata Grzywacz ◽  
Elżbieta Warchałowska-Śliwa ◽  
Maciej Kociński ◽  
Klaus-Gerhard Heller ◽  
Claudia Hemp
Keyword(s):  
Molecular Phylogeny ◽  
Large Scale ◽  
Diploid Number ◽  
Karyotype Analysis ◽  
Spatial Separation ◽  
Eastern Arc Mountains ◽  
East African ◽  
Habitat Islands ◽  
Extinction Event ◽  
Underlying Processes

AbstractEast African mountains constitute a network of isolated habitat islands among dry savannah and are thus ideal for studying species diversification processes. This study elucidated the phylogenetic and phylogeographic relationships of all bushcricket species comprising the genus Aerotegmina. Our analysis indicated that large-scale climatic and topographic processes in Africa are likely to have driven speciation in this group, and revealed the cytogenetic traits of the species. Molecular phylogeny supported the monophyly of Aerotegmina and showed that the genus probably originated in the old Eastern Arc Mountains of Tanzania and Kenya. Two lineages were distinguished: small- and large-sized species with geographically distinct habitats. The underlying processes are thought to be eight dispersals, ten vicariance events, and one extinction event linked to repeated fragmentation of the African rainforest. Those processes, in conjunction with habitat change, probably also led to the spatial separation of the species into a northern clade with a diploid number of chromosomes 2n = 32 + X0 or 2n = 30 + neo-XY and a southern clade with a reduced number of chromosomes (2n = 28 + X0 or 24 + neo-X1X2Y). Karyotype analysis suggests that Aerotegmina is currently in the process of speciation.

scholarly journals Chromosomal Instability at Fragile Sites in Blue Foxes, Silver Foxes, and Their Interspecific Hybrids

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1743
Author(s):  
Marta Kuchta-Gładysz ◽  
Ewa Wójcik ◽  
Anna Grzesiakowska ◽  
Katarzyna Rymuza ◽  
Olga Szeleszczuk
Keyword(s):  
Interspecific Hybrids ◽  
Genome Stability ◽  
Diploid Number ◽  
Fragile Sites ◽  
B Chromosomes ◽  
Silver Fox ◽  
Chromosomal Breaks ◽  
Blue Fox ◽  
Chromosomal Fragile Sites ◽  
Karyotypic Variation

A cytogenetic assay based on fragile sites (FS) enables the identification of breaks, chromatid gaps, and deletions. In healthy individuals, the number of these instabilities remains low. Genome stability in these species is affected by Robertsonian translocations in the karyotype of the blue fox and by B chromosomes in the silver fox. The aims of the study were to characterise the karyotype of blue foxes, silver foxes, and their hybrids and to identify chromosomal fragile sites used to evaluate genome stability. The diploid number of A chromosomes in blue foxes ranged from 48 to 50, while the number of B chromosomes in silver foxes varied from one to four, with a constant number of A chromosomes (2n = 34). In interspecific hybrids, both types of karyotypic variation were identified, with the diploid number of A chromosomes ranging from 40 to 44 and the number of B chromosomes varying from 0 to 3. The mean frequency of FS in foxes was 4.06 ± 0.19: 4.61 ± 0.37 in blue foxes, 3.46 ± 0.28 in silver foxes, and 4.12 ± 0.22 in hybrids. A relationship was identified between an increased number of A chromosomes in the karyotype of the hybrids and the frequency of chromosomal breaks. The FS assay was used as a biomarker for the evaluation of genomic stability in the animals in the study.

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