scholarly journals Centric Fusions behind the Karyotype Evolution of Neotropical Nannostomus Pencilfishes (Characiforme, Lebiasinidae): First Insights from a Molecular Cytogenetic Perspective

Genes ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 91 ◽  
Author(s):  
Alexandr Sember ◽  
Ezequiel Aguiar de Oliveira ◽  
Petr Ráb ◽  
Luiz Antonio Carlos Bertollo ◽  
Natália Lourenço de Freitas ◽  
...  
Keyword(s):  
Repetitive Dna ◽  
Small Body ◽  
5S Rdna ◽  
Chromosomal Mapping ◽  
Comparative Genomic ◽  
Comparative Genome Hybridization ◽  
Body Coloration ◽  
Rdna Sites ◽  
Karyotype Differentiation ◽  
Conventional Cytogenetics

Lebiasinidae is a Neotropical freshwater family widely distributed throughout South and Central America. Due to their often very small body size, Lebiasinidae species are cytogenetically challenging and hence largely underexplored. However, the available but limited karyotype data already suggested a high interspecific variability in the diploid chromosome number (2n), which is pronounced in the speciose genus Nannostomus, a popular taxon in ornamental fish trade due to its remarkable body coloration. Aiming to more deeply examine the karyotype diversification in Nannostomus, we combined conventional cytogenetics (Giemsa-staining and C-banding) with the chromosomal mapping of tandemly repeated 5S and 18S rDNA clusters and with interspecific comparative genomic hybridization (CGH) to investigate genomes of four representative Nannostomus species: N. beckfordi, N. eques, N. marginatus, and N. unifasciatus. Our data showed a remarkable variability in 2n, ranging from 2n = 22 in N. unifasciatus (karyotype composed exclusively of metacentrics/submetacentrics) to 2n = 44 in N. beckfordi (karyotype composed entirely of acrocentrics). On the other hand, patterns of 18S and 5S rDNA distribution in the analyzed karyotypes remained rather conservative, with only two 18S and two to four 5S rDNA sites. In view of the mostly unchanged number of chromosome arms (FN = 44) in all but one species (N. eques; FN = 36), and with respect to the current phylogenetic hypothesis, we propose Robertsonian translocations to be a significant contributor to the karyotype differentiation in (at least herein studied) Nannostomus species. Interspecific comparative genome hybridization (CGH) using whole genomic DNAs mapped against the chromosome background of N. beckfordi found a moderate divergence in the repetitive DNA content among the species’ genomes. Collectively, our data suggest that the karyotype differentiation in Nannostomus has been largely driven by major structural rearrangements, accompanied by only low to moderate dynamics of repetitive DNA at the sub-chromosomal level. Possible mechanisms and factors behind the elevated tolerance to such a rate of karyotype change in Nannostomus are discussed.

scholarly journals Tracking the Evolutionary Trends Among Small-Size Fishes of the Genus Pyrrhulina (Characiforme, Lebiasinidae): New Insights From a Molecular Cytogenetic Perspective

2021 ◽  
Vol 12 ◽  
Author(s):  
Renata Luiza Rosa de Moraes ◽  
Francisco de Menezes Cavalcante Sassi ◽  
Luiz Antonio Carlos Bertollo ◽  
Manoela Maria Ferreira Marinho ◽  
Patrik Ferreira Viana ◽  
...  
Keyword(s):  
Repetitive Dna ◽  
Sex Chromosome ◽  
Comparative Genomic ◽  
Comparative Genome Hybridization ◽  
Molecular Cytogenetic ◽  
Rdna Sites ◽  
Previous Hypothesis ◽  
History Of ◽  
Cytogenetic Analyses ◽  
High Dynamics

Miniature fishes have always been a challenge for cytogenetic studies due to the difficulty in obtaining chromosomal preparations, making them virtually unexplored. An example of this scenario relies on members of the family Lebiasinidae which include miniature to medium-sized, poorly known species, until very recently. The present study is part of undergoing major cytogenetic advances seeking to elucidate the evolutionary history of lebiasinids. Aiming to examine the karyotype diversification more deeply in Pyrrhulina, here we combined classical and molecular cytogenetic analyses, including Giemsa staining, C-banding, repetitive DNA mapping, comparative genomic hybridization (CGH), and whole chromosome painting (WCP) to perform the first analyses in five Pyrrhulina species (Pyrrhulina aff. marilynae, Pyrrhulina sp., P. obermulleri, P. marilynae and Pyrrhulina cf. laeta). The diploid number (2n) ranged from 40 to 42 chromosomes among all analyzed species, but P. marilynae is strikingly differentiated by having 2n = 32 chromosomes and a karyotype composed of large meta/submetacentric chromosomes, whose plesiomorphic status is discussed. The distribution of microsatellites does not markedly differ among species, but the number and position of the rDNA sites underwent significant changes among them. Interspecific comparative genome hybridization (CGH) found a moderate divergence in the repetitive DNA content among the species’ genomes. Noteworthy, the WCP reinforced our previous hypothesis on the origin of the X1X2Y multiple sex chromosome system in P. semifasciata. In summary, our data suggest that the karyotype differentiation in Pyrrhulina has been driven by major structural rearrangements, accompanied by high dynamics of repetitive DNAs.

scholarly journals Genomic Organization of Repetitive DNA Elements and Extensive Karyotype Diversity of Silurid Catfishes (Teleostei: Siluriformes): A Comparative Cytogenetic Approach

2019 ◽  
Vol 20 (14) ◽  
pp. 3545
Author(s):  
Sukhonthip Ditcharoen ◽  
Luiz Antonio Carlos Bertollo ◽  
Petr Ráb ◽  
Eva Hnátková ◽  
Wagner Franco Molina ◽  
...  
Keyword(s):  
Evolutionary Dynamics ◽  
Chromosomal Rearrangements ◽  
5S Rdna ◽  
Comparative Genomic ◽  
Molecular Cytogenetic ◽  
Rdna Sites ◽  
Genomic Divergence ◽  
Fish Chromosomes ◽  
Dna Elements ◽  
Repetitive Dna Elements

The catfish family Siluridae contains 107 described species distributed in Asia, but with some distributed in Europe. In this study, karyotypes and other chromosomal characteristics of 15 species from eight genera were examined using conventional and molecular cytogenetic protocols. Our results showed the diploid number (2n) to be highly divergent among species, ranging from 2n = 40 to 92, with the modal frequency comprising 56 to 64 chromosomes. Accordingly, the ratio of uni- and bi-armed chromosomes is also highly variable, thus suggesting extensive chromosomal rearrangements. Only one chromosome pair bearing major rDNA sites occurs in most species, except for Wallago micropogon, Ompok siluroides, and Kryptoterus giminus with two; and Silurichthys phaiosoma with five such pairs. In contrast, chromosomes bearing 5S rDNA sites range from one to as high as nine pairs among the species. Comparative genomic hybridization (CGH) experiments evidenced large genomic divergence, even between congeneric species. As a whole, we conclude that karyotype features and chromosomal diversity of the silurid catfishes are unusually extensive, but parallel some other catfish lineages and primary freshwater fish groups, thus making silurids an important model for investigating the evolutionary dynamics of fish chromosomes.

scholarly journals Karyotype differentiation and cytotaxonomic considerations in species of Serrasalmidae (Characiformes) from the Amazon basin

2012 ◽  
Vol 10 (1) ◽  
pp. 53-58 ◽  
Author(s):  
Celeste Mutuko Nakayama ◽  
Eliana Feldberg ◽  
Luiz Antonio Carlos Bertollo
Keyword(s):  
Amazon Basin ◽  
5S Rdna ◽  
Rrna Genes ◽  
Rdna Sites ◽  
Chromosomal Pair ◽  
Pair Number ◽  
5S Rrna Genes ◽  
Probable Occurrence ◽  
Acrocentric Chromosomes ◽  
Karyotype Differentiation

Six species of Serrasalmidae from the central Amazon, representatives of the genera Serrasalmus (S. elongatus, S. maculatus, S. cf. rhombeus, and S. rhombeus), Pygocentrus (P. nattereri), and Colossoma (C. macropomum), were analyzed regarding the distribution of the Ag-NORs, C-positive heterochromatin and 18S and 5S rRNA genes on the chromosomes. All specimens had 2n = 60 chromosomes, except S. cf. rhombeus, with 2n = 58, and C. macropomum with 2n = 54 chromosomes. The Ag-NORs were multiple and located on the short arms of subtelo-acrocentric chromosomes in all Serrasalmus species and in P. nattereri, but were found on metacentric chromosomes in C. macropomum. The 18S rDNA sites were usually coincident with Ag-NORs, although some species had a higher number and/or a distinct localization of these sites. C-positive heterochromatin was preferentially situated in centromeric regions, remarkably on metacentric pair number 7 in all Serrasalmus species and number 3 in P. nattereri, which beared a conspicuous proximal C-band on the long arms. The 5S rDNA sites were detected in a single chromosomal pair in all species. In Serrasalmus and P. nattereri, this pair was the number 7 and 3, respectively, thereby revealing its co-localization with the conspicuous heterochromatic band. However, in C. macropomum, only one homologue (probably belonging to pair number 12) exhibited 5S rDNA sites on the short arms, close to the centromere. The present data revealed reliable cytotaxonomic markers, enabling the evaluation of karyotype differentiation and interrelationships among Serrasalmidae, as well as the probable occurrence of a species complex in S. rhombeus.

Chromosomal Mapping of Repeat DNA in Bergiaria westermanni (Pimelodidae, Siluriformes): Localization of 45S rDNA in B Chromosomes

2018 ◽  
Vol 154 (2) ◽  
pp. 99-106 ◽  
Author(s):  
Geovana C. Malimpensa ◽  
Josiane B. Traldi ◽  
Danyelle Toyama ◽  
Flávio Henrique-Silva ◽  
Marcelo R. Vicari ◽  
...  
Keyword(s):  
Chromosomal Rearrangements ◽  
Indirect Evidence ◽  
5S Rdna ◽  
B Chromosomes ◽  
Chromosomal Mapping ◽  
Interindividual Variation ◽  
Rrna Genes ◽  
45S Rdna ◽  
Rdna Sites ◽  
Repeat Dna

The occurrence of repetitive DNA in autosomes and B chromosomes of Bergiaria westermanni was examined using conventional and molecular cytogenetic techniques. This species exhibited 2n = 56 chromosomes, with intra- and interindividual variation in the number of heterochromatic B chromosomes (from 0 to 4). The 5S rDNA was localized in pairs 1 and 5, and histone probes (H1, H3, and H4) and U2 small nuclear RNA were syntenic with 5S rDNA in pair 5. Histone sequences were also located in chromosome pair 14. The (GATA)n sequence was dispersed throughout the autosomes and B chromosomes, with clusters (microsatellite accumulation) in some chromosome regions. The telomeric probe revealed no signs of chromosomal rearrangements in the genome of B. westermanni. The 45S rDNA sites were detected in the terminal region of pair 27; these sites corresponded to a GC-rich heterochromatin block. In addition, 3 of the 4 B chromosomes also contained 45S rDNA copies. Silver nitrate staining in interphase nuclei provided indirect evidence of the expression of these rRNA genes in B chromosomes, indicating the probable origin of these elements. This report shows plasticity in the chromosomal localization of repeat DNA in B. westermanni and features a discussion of genomic diversification.

scholarly journals Deciphering the Origin and Evolution of the X1X2Y System in Two Closely-Related Oplegnathus Species (Oplegnathidae and Centrarchiformes)

2019 ◽  
Vol 20 (14) ◽  
pp. 3571 ◽  
Author(s):  
Dongdong Xu ◽  
Alexandr Sember ◽  
Qihui Zhu ◽  
Ezequiel Aguiar de Oliveira ◽  
Thomas Liehr ◽  
...  
Keyword(s):  
Y Chromosome ◽  
Repetitive Dna ◽  
Sex Chromosomes ◽  
5S Rdna ◽  
Reef Fishes ◽  
Comparative Genomic ◽  
Rocky Reef ◽  
Oplegnathus Fasciatus ◽  
Evolutionary Forces ◽  
Y Chromosomes

Oplegnathus fasciatus and O. punctatus (Teleostei: Centrarchiformes: Oplegnathidae), are commercially important rocky reef fishes, endemic to East Asia. Both species present an X1X2Y sex chromosome system. Here, we investigated the evolutionary forces behind the origin and differentiation of these sex chromosomes, with the aim to elucidate whether they had a single or convergent origin. To achieve this, conventional and molecular cytogenetic protocols, involving the mapping of repetitive DNA markers, comparative genomic hybridization (CGH), and whole chromosome painting (WCP) were applied. Both species presented similar 2n, karyotype structure and hybridization patterns of repetitive DNA classes. 5S rDNA loci, besides being placed on the autosomal pair 22, resided in the terminal region of the long arms of both X1 chromosomes in females, and on the X1 and Y chromosomes in males. Furthermore, WCP experiments with a probe derived from the Y chromosome of O. fasciatus (OFAS-Y) entirely painted the X1 and X2 chromosomes in females and the X1, X2, and Y chromosomes in males of both species. CGH failed to reveal any sign of sequence differentiation on the Y chromosome in both species, thereby suggesting the shared early stage of neo-Y chromosome differentiation. Altogether, the present findings confirmed the origin of the X1X2Y sex chromosomes via Y-autosome centric fusion and strongly suggested their common origin.

scholarly journals Chromosomal Mapping of 18S-25S and 5S Ribosomal Genes on 15 Species of Fagaceae From Northern Thailand

2008 ◽  
Vol 57 (1-6) ◽  
pp. 5-13 ◽  
Author(s):  
P. Chokchaichamnankit ◽  
K. Anamthawat-Jónsson ◽  
W. Chulalaksananukul
Keyword(s):  
In Situ Hybridisation ◽  
5S Rdna ◽  
Ribosomal Genes ◽  
Chromosomal Mapping ◽  
Hybrid Origin ◽  
Fluorescence In Situ Hybridisation ◽  
Northern Thailand ◽  
Quercus Species ◽  
Rdna Sites ◽  
25S Rdna

Abstract Fifteen species of Fagaceae from Chiang Mai province, northern Thailand, were investigated: eight Castanopsis, four Lithocarpus and three Quercus species. The species were generally diploid with the chromosome number 2n = 24, and the basic number x =12 was confirmed in some species with meiosis. One tree belonging to Q. lenticellatus had 2n = 14. Chromosomal mapping of the highly repetitive 18S-25S and 5S ribosomal genes by fluorescence in situ hybridisation (FISH) was performed. Most species (from all three genera) showed four 18S-25S rDNA sites (two pairs: one subterminal major and one paracentromeric/intercalary minor loci) and two 5S rDNA sites (one pair: paracentromeric locus). Quercus kerrii also had two pairs of 18S-25S rDNA sites, but both were subterminal major loci. Two species, C. argentea and Q. brandisianus, only had one pair of 18S-25S rDNA sites. Two species, C. calathiformis and L. vestitus, showed an odd number of (unpaired) sites, and this indicated hybrid origin and/or polyploidy. Polyploid cells were detected in these species. The ribosomal gene maps based on both sequences together were genus-specific. In Castanopsis, the 18S-25S and the 5S genes were localized on three different chromosome pairs, and comprised species-specific maps. On the other hand, the ribosomal genes in Lithocarpus and Quercus were found only on two chromosome pairs, because one of the two 18S-25S rDNA loci was localized on the same chromosome as the 5S rDNA locus. The FISH markers may be used to clarify discrepancies arising from morphological assessments.

scholarly journals Adding New Pieces to the Puzzle of Karyotype Evolution in Harttia (Siluriformes, Loricariidae): Investigation of Amazonian Species

Biology ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 922
Author(s):  
Francisco de M. C. Sassi ◽  
Orlando Moreira-Filho ◽  
Geize A. Deon ◽  
Alexandr Sember ◽  
Luiz A. C. Bertollo ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
Sex Chromosome ◽  
5S Rdna ◽  
Morphological Diversity ◽  
High Rate ◽  
Comparative Genomic ◽  
Chromosomal Distribution ◽  
Single Chromosome ◽  
Male Genome ◽  
Rdna Sites

A remarkable morphological diversity and karyotype variability can be observed in the Neotropical armored catfish genus Harttia. These fishes offer a useful model to explore both the evolution of karyotypes and sex chromosomes, since many species possess male-heterogametic sex chromosome systems and a high rate of karyotype repatterning. Based on the karyotype organization, the chromosomal distribution of several repetitive DNA classes, and the rough estimates of genomic divergences at the intraspecific and interspecific levels via Comparative Genomic Hybridization, we identified shared diploid chromosome numbers (2n = 54) but different karyotype compositions in H. dissidens (20m + 26sm + 8a) and Harttia sp. 3 (16m + 18sm + 14st + 6a), and different 2n in H. guianensis (2n = 58; 20m + 26sm + 2st + 10a). All species further displayed similar patterns of chromosomal distribution concerning constitutive heterochromatin, 18S ribosomal DNA (rDNA) sites, and most of the surveyed microsatellite motifs. Furthermore, differences in the distribution of 5S rDNA sites and a subset of microsatellite sequences were identified. Heteromorphic sex chromosomes were lacking in H. dissidens and H. guianensis at the scale of our analysis. However, one single chromosome pair in Harttia sp. 3 males presented a remarkable accumulation of male genome-derived probe after CGH, pointing to a tentative region of early sex chromosome differentiation. Thus, our data support already previously outlined evidence that Harttia is a vital model for the investigation of teleost karyotype and sex chromosome dynamics.

scholarly journals Taxonomic Diversity Not Associated with Gross Karyotype Differentiation: The Case of Bighead Carps, Genus Hypophthalmichthys (Teleostei, Cypriniformes, Xenocyprididae)

Genes ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 479 ◽  
Author(s):  
Alexandr Sember ◽  
Šárka Pelikánová ◽  
Marcelo de Bello Cioffi ◽  
Vendula Šlechtová ◽  
Terumi Hatanaka ◽  
...  
Keyword(s):  
Constitutive Heterochromatin ◽  
Taxonomic Diversity ◽  
The Other ◽  
Chromosomal Mapping ◽  
Single Pair ◽  
Pure Species ◽  
Other Hand ◽  
Rdna Sites ◽  
Karyotype Structure ◽  
Karyotype Differentiation

The bighead carps of the genus Hypophthalmichthys (H. molitrix and H. nobilis) are important aquaculture species. They were subjected to extensive multidisciplinary research, but with cytogenetics confined to conventional protocols only. Here, we employed Giemsa-/C-/CMA3- stainings and chromosomal mapping of multigene families and telomeric repeats. Both species shared (i) a diploid chromosome number 2n = 48 and the karyotype structure, (ii) low amount of constitutive heterochromatin, (iii) the absence of interstitial telomeric sites (ITSs), (iv) a single pair of 5S rDNA loci adjacent to one major rDNA cluster, and (v) a single pair of co-localized U1/U2 snDNA tandem repeats. Both species, on the other hand, differed in (i) the presence/absence of remarkable interstitial block of constitutive heterochromatin on the largest acrocentric pair 11 and (ii) the number of major (CMA3-positive) rDNA sites. Additionally, we applied here, for the first time, the conventional cytogenetics in H. harmandi, a species considered extinct in the wild and/or extensively cross-hybridized with H. molitrix. Its 2n and karyotype description match those found in the previous two species, while silver staining showed differences in distribution of major rDNA. The bighead carps thus represent another case of taxonomic diversity not associated with gross karyotype differentiation, where 2n and karyotype structure cannot help in distinguishing between genomes of closely related species. On the other hand, we demonstrated that two cytogenetic characters (distribution of constitutive heterochromatin and major rDNA) may be useful for diagnosis of pure species. The universality of these markers must be further verified by analyzing other pure populations of bighead carps.

scholarly journals Chromosomal Mapping of Repetitive DNA Sequences in Five Species of Astyanax (Characiformes, Characidae) Reveals Independent Location of U1 and U2 snRNA Sites and Association of U1 snRNA and 5S rDNA

2015 ◽  
Vol 146 (2) ◽  
pp. 144-152 ◽  
Author(s):  
Duilio M.Z.A. Silva ◽  
Ricardo Utsunomia ◽  
José C. Pansonato-Alves ◽  
Cláudio Oliveira ◽  
Fausto Foresti
Keyword(s):  
Repetitive Dna ◽  
Dna Sequences ◽  
Repetitive Sequences ◽  
5S Rdna ◽  
Chromosomal Mapping ◽  
Valid Species ◽  
Small Nuclear Rna ◽  
U2 Snrna ◽  
Rdna Sequences ◽  
U1 Snrna

Astyanax is a genus of Characidae fishes currently composed of 155 valid species. Previous cytogenetic studies revealed high chromosomal diversification among them, and several studies have been performed using traditional cytogenetic techniques to investigate karyotypes and chromosomal locations of 18S and 5S rDNA genes. However, only a few studies are currently available about other repetitive sequences. Here, the chromosomal location of small nuclear RNA genes, identified as U1 and U2 snRNA clusters, was established and compared to the distribution of 5S rDNA and histone clusters in 5 Astyanax species (A. paranae, A. fasciatus, A. bockmanni, A. altiparanae, and A. jordani) using FISH. The cytogenetic mapping of U1 and U2 snRNA demonstrated a conserved pattern in the number of sites per genome independent of the location in Astyanax species. The location of the U1 snRNA gene was frequently associated with 5S rDNA sequences, indicating a possible interaction between the distinct repetitive DNA families. Finally, comparisons involving the location of U1 and U2 snRNA clusters in the chromosomes of Astyanax species revealed a very diverse pattern, suggesting that many rearrangements have occurred during the diversification process of this group.

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