Cytogenetic analysis in Polypterus ornatipinnis (Actinopterygii, Cladistia, Polypteridae) and 5S rDNA

Morescalchi, M. A.; Stingo, Vincenzo; Capriglione, Teresa

doi:10.1016/j.margen.2010.12.002

Cited by 10 publications

(9 citation statements)

References 74 publications

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“…Deiana et al [ 68 ] attributed this feature to the presence of GC-rich repeats in NTS. Particularly interesting was the observation of all centromeres being CMA 3 + in S. corica – a similar feature as, for instance, in Gobiidae [ 71 , 72 ] and Polypteriformes [ 73 ]. Also in the genus Cobitis , high number of CMA 3 + regions were recorded which were non-related to NORs (together with CMA 3 -negative NOR sites) [ 74 ].…”

Section: Discussionmentioning

confidence: 60%

Karyotype differentiation in 19 species of river loach fishes (Nemacheilidae, Teleostei): extensive variability associated with rDNA and heterochromatin distribution and its phylogenetic and ecological interpretation

et al. 2015

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BackgroundLoaches of the family Nemacheilidae are one of the most speciose elements of Palearctic freshwater ichthyofauna and have undergone rapid ecological adaptations and colonizations. Their cytotaxonomy is largely unexplored; with the impact of cytogenetical changes on this evolutionary diversification still unknown. An extensive cytogenetical survey was performed in 19 nemacheilid species using both conventional (Giemsa staining, C- banding, Ag- and Chromomycin A3/DAPI stainings) and molecular (fluorescence in situ hybridization with 5S rDNA, 45S rDNA, and telomeric (TTAGGG)n probes) methods. A phylogenetic tree of the analysed specimens was constructed based on one mitochondrial (cytochrome b) and two nuclear (RAG1, IRBP) genes.ResultsSeventeen species showed karyotypes composed of 2n = 50 chromosomes but differentiated by fundamental chromosome number (NF = 68–90). Nemachilichthys ruppelli (2n = 38) and Schistura notostigma (2n = 44–48) displayed reduced 2n with an elevated number of large metacentric chromosomes. Only Schistura fasciolata showed morphologically differentiated sex chromosomes with a multiple system of the XY1Y2 type. Chromomycin A3 (CMA3)- fluorescence revealed interspecific heterogeneity in the distribution of GC-rich heterochromatin including its otherwise very rare association with 5S rDNA sites. The 45S rDNA sites were mostly located on a single chromosome pair contrasting markedly with a pattern of two (Barbatula barbatula, Nemacheilus binotatus, N. ruppelli) to 20 sites (Physoschistura sp.) of 5S rDNA. The cytogenetic changes did not follow the phylogenetic relationships between the samples. A high number of 5S rDNA sites was present in species with small effective population sizes.ConclusionDespite a prevailing conservatism of 2n, Nemacheilidae exhibited a remarkable cytogenetic variability on microstructural level. We suggest an important role for pericentric inversions, tandem and centric fusions in nemacheilid karyotype differentiation. Short repetitive sequences, genetic drift, founder effect, as well as the involvement of transposable elements in the dispersion of ribosomal DNA sites, might also have played a role in evolutionary processes such as reproductive isolation. These remarkable dynamics of their genomes qualify river loaches as a model for the study of the cytogenetic background of major evolutionary processes such as radiation, endemism and colonization of a wide range of habitats.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-015-0532-9) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 60%

Karyotype differentiation in 19 species of river loach fishes (Nemacheilidae, Teleostei): extensive variability associated with rDNA and heterochromatin distribution and its phylogenetic and ecological interpretation

et al. 2015

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“…; Morescalchi et al . ). Within the family Gadidae, two differently sized 5S rDNAs have been found in a close relative of the Atlantic cod, Arctogadus glacialis (GenBank , ).…”

Section: Discussionmentioning

confidence: 97%

Karyotyping and cytogenetic mapping of Atlantic cod (Gadus morhua Linnaeus, 1758)

et al. 2012

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Summary The Atlantic cod (Gadus morhua) is an important natural resource for northern societies and is now also considered to be a promising candidate for aquaculture. In recent years, much effort has been directed towards the development of genomic tools, and genome initiatives for Atlantic cod have been established. Despite the growing attention devoted to the Atlantic cod genomics, basic aspects of its genome structure and organization remain unknown. Thus, the present work aims to study cytogenetic features of the Atlantic cod as a contribution to the knowledge of this species' genome. The Atlantic cod displays a diploid number of 46 chromosomes, with a karyotypic formula 16 m/sm + 30 st/t. Conventional karyotyping was improved by chromosomal mapping of two classes of repetitive sequences. 18S rDNA clusters were assigned to pairs 2 and 4; small amounts of 18S rDNA clusters were occasionally detected on pair 5. These findings could not be related to the geographical origin of the specimens, but were consistent with the variability of these repeated genes in fish in general. 5S ribosomal gene clusters, apparently corresponding to a single 5S rDNA class, were detected on twelve chromosomes (pairs 11, 12, 14, 17, 20 and 21). The present update of the existing but meagre information on the karyotype of Atlantic cod, plus the first physical mapping of repetitive genes in this species herein, opens the way for an integrated approach that combines genetic and physical mapping with the assembly of the genome of this commercially important species.

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“…Polypterids exhibits the lowest chromosomal counts among other nonteleost actinopterygians and at the same time huge chromosome sizes. All analyzed bichirs and ropefish (Morescalchi et al., and references therein) possess 2 n = 36, except P. weeksii where 2 n = 38 was likely caused by a centric fission of one metacentric chromosome and P. dolloi with 2 n = 68, an apparent case of autopolyploidy without noticeable morphological effects (Vervoort, '80). Except the last mentioned, their karyotypes composed exclusively by biarmed and extremely large chromosomes.…”

Section: Discussionmentioning

confidence: 99%

“Holostei versus Halecostomi” Problem: Insight from Cytogenetics of Ancient Nonteleost Actinopterygian Fish, Bowfin Amia calva

et al. 2017

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Bowfin belongs to an ancient lineage of nonteleost ray-finned fishes (actinopterygians) and is the only extant survivor of a once diverged group, the Halecomorphi or Amiiformes. Owing to the scarcity of extant nonteleost ray-finned lineages, also referred as "living fossils," their phylogenetic interrelationships have been the target of multiple hypotheses concerning their sister group relationships. Molecular and morphological data sets have produced controversial results; bowfin is considered as either the sister group to genome-duplicated teleosts (together forming the group of Halecostomi) or to gars (Lepisosteiformes; together forming the group of Holostei). However, any detailed cytogenetic analysis of bowfin chromosomes has never been performed to address this issue. Here we examined bowfin chromosomes by conventional (Giemsa-staining, C-banding, base-specific fluorescence and silver staining) and molecular (FISH with rDNA probes) cytogenetic protocols. We identified diploid chromosome number 2n = 46 with a middle-sized submetacentric chromosome pair as the major ribosomal DNA-bearing (45S rDNA), GC-positive and silver-positive element. The minor rDNA (5S rDNA) sites were localized in the pericentromeric region of one middle-sized acrocentric chromosome pair. Comparison with available cytogenetic data of other nonteleost actinopterygians (bichirs, sturgeons, gars) and teleost species including representative of basally branching lineages showed bowfin chromosomal characteristics more similar to the teleost type than to any other nonteleosts. Particularly striking differences were identified between bowfin and gars, the latter of which were found to mimic mammalian AT/GC genomic organisation. Such conclusion however contradicts the most recent phylogenomic results and raises the question what states are ancestral and what are derived.

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Cytogenetic analysis in Polypterus ornatipinnis (Actinopterygii, Cladistia, Polypteridae) and 5S rDNA

Cited by 10 publications

References 74 publications

Karyotype differentiation in 19 species of river loach fishes (Nemacheilidae, Teleostei): extensive variability associated with rDNA and heterochromatin distribution and its phylogenetic and ecological interpretation

Karyotype differentiation in 19 species of river loach fishes (Nemacheilidae, Teleostei): extensive variability associated with rDNA and heterochromatin distribution and its phylogenetic and ecological interpretation

Karyotyping and cytogenetic mapping of Atlantic cod (Gadus morhua Linnaeus, 1758)

“Holostei versus Halecostomi” Problem: Insight from Cytogenetics of Ancient Nonteleost Actinopterygian Fish, Bowfin Amia calva

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