Latest Articles from Comparative Cytogenetics Latest 61 Articles from Comparative Cytogenetics https://compcytogen.pensoft.net/ Thu, 28 Mar 2024 12:40:36 +0200 Pensoft FeedCreator https://compcytogen.pensoft.net/i/logo.jpg Latest Articles from Comparative Cytogenetics https://compcytogen.pensoft.net/ Divergent karyotypes in five genera of the African endemic fish family Distichodontidae (Cithariniformes, Osteichthyes) https://compcytogen.pensoft.net/article/107744/ Comparative Cytogenetics 17: 251-262

DOI: 10.3897/compcytogen.17.107744

Authors: Sergey A. Simanovsky, Dmitry A. Medvedev, Fekadu Tefera, Alexander S. Golubtsov

Abstract: The African family Distichodontidae comprises 109 species in 16 genera. Up-to-date cytogenetic information was available for the only distichodontid species Distichodus affinis Günther, 1873. Here we report chromosome number and morphology in: Distichodus engycephalus Günther, 1864 (2n = 52, FN = 104), Ichthyborus besse (Joannis, 1835) (2n = 46, FN = 92), Nannocharax niloticus (Joannis, 1835) (2n = 54, FN = 106) and three taxa, Nannaethiops bleheri Géry et Zarske, 2003, Nannaethiops sp., and Neolebias unifasciatus Steindachner, 1894, that exhibit the same karyotypes (2n = 50, FN = 98). To confirm the Nannaethiops Günther, 1872 and Neolebias Steindachner, 1894 species identification, mt-DNA sequences of the two markers (COI and 16S rRNA) were obtained from karyotyped specimens and compared with the relevant sequences accessible from GenBank. The great prevalence of biarmed chromosomes (the karyotypes of most species contain exclusively biarmed chromosomes) is a distinctive characteristic of Distichodontidae and Cithariniformes as a whole.

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Research Article Thu, 2 Nov 2023 14:06:58 +0200
Karyotype of Sabanejewia bulgarica (Drensky, 1928) (Teleostei, Cobitidae) from the Danube Delta, Romania https://compcytogen.pensoft.net/article/103152/ Comparative Cytogenetics 17: 157-162

DOI: 10.3897/compcytogen.17.103152

Authors: Eva Hnátková, Zuzana Majtánová, Vendula Bohlen Šlechtová, Joerg Bohlen, Petr Ráb

Abstract: The karyotype of the freshwater fish Sabanejewia bulgarica (Drensky, 1928), from the Danube Delta, was studied by conventional Giemsa staining and the C-banding technique. The diploid chromosome number was 2n = 50. The karyotype contained 2 pairs of metacentric (the first one was much larger than the second one), 6 pairs of submetacentric and 17 pairs of subtelocentric to acrocentric chromosomes. Pericentromeric blocks of heterochromatin were revealed in most of the chromosome pairs. The karyotype phenotype of S. bulgarica was the same as found for S. balcanica from Northern Carpathian Mountains.

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Short Communication Wed, 5 Jul 2023 10:41:04 +0300
Karyotype differentiation in the Nothobranchius ugandensis species group (Teleostei, Cyprinodontiformes), seasonal fishes from the east African inland plateau, in the context of phylogeny and biogeography https://compcytogen.pensoft.net/article/97165/ Comparative Cytogenetics 17: 13-29

DOI: 10.3897/compcytogen.v7.i1.97165

Authors: Eugene Yu. Krysanov, Béla Nagy, Brian R. Watters, Alexandr Sember, Sergey A. Simanovsky

Abstract: The karyotype differentiation of the twelve known members of the Nothobranchius ugandensis Wildekamp, 1994 species group is reviewed and the karyotype composition of seven of its species is described herein for the first time using a conventional cytogenetic protocol. Changes in the architecture of eukaryotic genomes often have a major impact on processes underlying reproductive isolation, adaptation and diversification. African annual killifishes of the genus Nothobranchius Peters, 1868 (Teleostei: Nothobranchiidae), which are adapted to an extreme environment of ephemeral wetland pools in African savannahs, feature extensive karyotype evolution in small, isolated populations and thus are suitable models for studying the interplay between karyotype change and species evolution. The present investigation reveals a highly conserved diploid chromosome number (2n = 36) but a variable number of chromosomal arms (46–64) among members of the N. ugandensis species group, implying a significant role of pericentric inversions and/or other types of centromeric shift in the karyotype evolution of the group. When superimposed onto a phylogenetic tree based on molecular analyses of two mitochondrial genes the cytogenetic characteristics did not show any correlation with the phylogenetic relationships within the lineage. While karyotypes of many other Nothobranchius spp. studied to date diversified mainly via chromosome fusions and fissions, the N. ugandensis species group maintains stable 2n and the karyotype differentiation seems to be constrained to intrachromosomal rearrangements. Possible reasons for this difference in the trajectory of karyotype differentiation are discussed. While genetic drift seems to be a major factor in the fixation of chromosome rearrangements in Nothobranchius, future studies are needed to assess the impact of predicted multiple inversions on the genome evolution and species diversification within the N. ugandensis species group.

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Research Article Tue, 31 Jan 2023 18:54:24 +0200
Chromosome complements of Channa lucius and C. striata from Phu Quoc Island and karyotypic evolution in snakehead fishes (Actinopterygii, Channidae) https://compcytogen.pensoft.net/article/94943/ Comparative Cytogenetics 17: 1-12

DOI: 10.3897/compcytogen.v17.i1.94943

Authors: Denis V. Prazdnikov

Abstract: Snakehead fishes of the family Channidae are obligatory air-breathers freshwater predators, the vast majority of which belong to the genus Channa Scopoli, 1777. Channa species are characterized by high karyotypic diversity due to various types of chromosomal rearrangements. It is assumed that, in addition to the lifestyle, fragmentation and isolation of snakehead populations contribute to an increase in karyotypic diversity. However, the chromosome complements of many isolated populations of widespread Channa species remain unknown, and the direction of karyotype transformations is poorly understood. This paper describes the previously unstudied karyotypes of Channa lucius (Cuvier, 1831) and C. striata (Bloch, 1793) from Phu Quoc Island and analyzes the trends of karyotypic evolution in the genus Channa. In C. lucius, the karyotypes are differed in the number of chromosome arms (2n = 48, NF = 50 and 51), while in C. striata, the karyotypes are differed in the diploid chromosome number (2n = 44 and 43, NF = 48). A comparative cytogenetic analysis showed that the main trend of karyotypic evolution of Channa species is associated with a decrease in the number of chromosomes and an increase in the number of chromosome arms, mainly due to fusions and pericentric inversions. The data obtained support the assumption that fragmentation and isolation of populations, especially of continental islands, contribute to the karyotypic diversification of snakeheads and are of interest for further cytogenetic studies of Channidae.

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Research Article Tue, 3 Jan 2023 10:07:04 +0200
First cytogenetic data on Afrotropical lutefishes (Citharinidae) in the light of karyotype evolution in Characiformes https://compcytogen.pensoft.net/article/79133/ Comparative Cytogenetics 16(2): 143-150

DOI: 10.3897/compcytogen.v16.i2.79133

Authors: Sergey A. Simanovsky, Dmitry A. Medvedev, Fekadu Tefera, Alexander S. Golubtsov

Abstract: The Afrotropical lutefish family Citharinidae (Citharinoidei, Characiformes) comprises three genera with eight species in total. Although Citharinidae have been studied in terms of taxonomy and systematics, no cytogenetic information was available for any representative of the family. Furthermore, only one species out of 116 in Citharinoidei (Distichodus affinis Günther, 1873) has been studied cytogenetically. Here, we report the karyotypes of Citharinus citharus (Geoffroy St. Hilaire, 1809) from West Africa and Citharinus latus Müller et Troschel, 1844 from Northeast Africa. The former has the diploid chromosome number 2n = 40 and the fundamental number FN = 80, while the latter has 2n = 44 and FN = 88. Hence, these karyotypes consist exclusively of bi-armed chromosomes. Such karyotypes were previously found in D. affinis and in many lineages of Neotropical species of another suborder of Characiformes, Characoidei. In contrast, the karyotypes dominated by uni-armed elements are typical for a number of phylogenetically basal lineages of Afrotropical and Neotropical Characoidei. We discuss the importance of our data on Citharinidae for the understanding of the karyotype evolution within the order Characiformes.

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Research Article Tue, 21 Jun 2022 16:04:50 +0300
Karyotype description and comparative chromosomal mapping of rDNA and U2 snDNA sequences in Eigenmannia limbata and E. microstoma (Teleostei, Gymnotiformes, Sternopygidae) https://compcytogen.pensoft.net/article/72190/ Comparative Cytogenetics 16(2): 127-142

DOI: 10.3897/CompCytogen.v16i2.72190

Authors: Cristian Andrés Araya-Jaime, Duílio Mazzoni Zerbinato de Andrade Silva, Luís Ricardo Ribeiro da Silva, Cristiano Neves do Nascimento, Claudio Oliveira, Fausto Foresti

Abstract: The genus Eigenmannia Jordan et Evermann,1896 includes electric fishes endemic to the Neotropical region with extensive karyotype variability and occurrence of different sex chromosome systems, however, cytogenetic studies within this group are restricted to few species. Here, we describe the karyotypes of Eigenmannia limbata (Schreiner et Miranda Ribeiro, 1903) and E. microstoma (Reinhardt, 1852) and the chromosomal locations of 5S and 18S rDNAs (ribosomal RNA genes) and U2 snDNA (small nuclear RNA gene). Among them, 18S rDNA sites were situated in only one chromosomal pair in both species, and co-localized with 5S rDNA in E. microstoma. On the other hand, 5S rDNA and U2 snRNA sites were observed on several chromosomes, with variation in the number of sites between species under study. These two repetitive DNAs were observed co-localized in one chromosomal pair in E. limbata and in four pairs in E. microstoma. Our study shows a new case of association of these two types of repetitive DNA in the genome of Gymnotiformes.

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Research Article Thu, 5 May 2022 11:17:35 +0300
Comparative cytogenetic patterns in Carangidae fishes in association with their distribution range https://compcytogen.pensoft.net/article/69638/ Comparative Cytogenetics 15(4): 429-445

DOI: 10.3897/CompCytogen.v15.i4.69638

Authors: Rodrigo Xavier Soares, Clóvis Coutinho da Motta-Neto, Gideão Wagner Werneck Félix da Costa, Marcelo de Bello Cioffi, Luiz Antonio Carlos Bertollo, Amanda Torres Borges, Wagner Franco Molina

Abstract: Carangidae are an important and widespreaded family of pelagic predatory fishes that inhabit reef regions or open ocean areas, some species occupying a vast circumglobal distribution. Cytogenetic comparisons among representatives of its different tribes help to understand the process of karyotype divergence in marine ecosystems due to the variable migratory ability of species. In this sense, conventional cytogenetic investigations (Giemsa staining, Ag-NORs, and C-banding), GC base-specific fluorochrome staining and FISH mapping of ribosomal DNAs were performed. Four species, Elagatis bipinnulata (Quoy et Gaimard, 1825) and Seriola rivoliana (Valenciennes, 1883) (Naucratini), with circumtropical distributions, Gnathanodon speciosus (Forsskål, 1775) (Carangini), widely distributed in the tropical and subtropical waters of the Indian and Pacific oceans, and Trachinotus carolinus (Linnaeus, 1766) (Trachinotini), distributed along the western Atlantic Ocean, were analyzed, thus encompassing representatives of three out its four tribes. All species have diploid chromosome number 2n = 48, with karyotypes composed mainly by acrocentric chromosomes (NF = 50–56). The 18S rDNA/Ag-NORs/GC+ and 5S rDNA loci were located on chromosomes likely homeologs. Karyotypes showed a pattern considered basal for the family or with small variations in their structures, apparently due to pericentric inversions. The migratory capacity of large pelagic swimmers, in large distribution areas, likely restricts the fixation of chromosome changes in Carangidae responsible for a low level of karyotype diversification.

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Research Article Wed, 1 Dec 2021 17:06:02 +0200
Derived karyotypes in two elephantfish genera (Hyperopisus and Pollimyrus): lowest chromosome number in the family Mormyridae (Osteoglossiformes) https://compcytogen.pensoft.net/article/67681/ Comparative Cytogenetics 15(4): 345-354

DOI: 10.3897/compcytogen.v15.i4.67681

Authors: Sergey Simanovsky, Dmitry Medvedev, Fekadu Tefera, Alexander Golubtsov

Abstract: The African weakly electric elephantfish family Mormyridae comprises 22 genera and almost 230 species. Up-to-date cytogenetic information was available for 17 species representing 14 genera. Here we report chromosome number and morphology in Hyperopisus bebe (Lacepède, 1803) and Pollimyrus isidori (Valenciennes, 1847) collected from the White Nile system in southwestern Ethiopia. Both taxa displayed the diploid chromosome number 2n = 40, but they differed in fundamental numbers: FN = 66 in H. bebe and FN = 72 in P. isidori; previously the same diploid chromosome number 2n = 40 was reported in an undescribed species of Pollimyrus Taverne, 1971 (FN = 42) from the same region. Our results demonstrate that not only pericentric inversions, but fusions also played a substantial role in the evolution of the mormyrid karyotype structure. If the hypothesis that the karyotype structure with 2n = 50–52 and prevalence of the uni-armed chromosomes close to the ancestral condition for the family Mormyridae is correct, the most derived karyotype structures are found in the Mormyrus Linnaeus, 1758 species with 2n = 50 and the highest number of bi-armed elements in their compliments compared to all other mormyrids and in Pollimyrus isidori with the highest number of bi-armed elements among the mormyrids with 2n = 40.

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Research Article Fri, 8 Oct 2021 16:34:22 +0300
Differentiation of the frog sculpin Myoxocephalus stelleri Tilesius, 1811 (Actinopterygii, Cottidae) based on mtDNA and karyotype analyses https://compcytogen.pensoft.net/article/63207/ Comparative Cytogenetics 15(2): 179-197

DOI: 10.3897/CompCytogen.v15.i2.63207

Authors: Irina N. Moreva, Olga A. Radchenko, Anna V. Petrovskaya

Abstract: A molecular genetic and karyological study of the frog sculpin Myoxocephalus stelleri Tilesius, 1811 was carried out on an extensive sample from a large area of the species’ range. A total of 42 specimens was sampled from the Sea of Japan, Sea of Okhotsk, and coastal waters off the southern Kuril Islands, which makes this sampling scheme the most comprehensive to date. The level of mtDNA polymorphism was found to be low. The haplotypes of the species formed three phylogenetic groups. The unique M. stelleri haplotype from the coast of Shikotan Island linked all the studied groups, indicating that it is likely ancestral. Robertsonian polymorphism was identified in the species. In all five cytotypes (I – 2n = 44, II – 2n = 43, III – 2n = 42, IV – 2n = 41, V – 2n = 40; NF = 44+2) were identified, all of which were present in the Sea of Japan. Only one (cytotype I) was found in the Sea of Okhotsk, which is probably the closest to the ancestral karyotype. The significant chromosomal polymorphism and the presence of common haplotypes in the studied samples indicate their recent origin from a common ancestor and/or relatively recent contacts within the range. The discrepancies between mtDNA and karyotypes in assigning the ancestral M. stelleri to the coastal waters off Shikotan Island (southern Kuril Islands) and the Sea of Okhotsk, respectively, can be explained by the different inheritance mechanisms and the rates of evolution of molecular genetic and karyological traits.

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Research Article Mon, 14 Jun 2021 13:38:10 +0300
Comparative study of four Mystus species (Bagridae, Siluriformes) from Thailand: insights into their karyotypic diversity https://compcytogen.pensoft.net/article/60649/ Comparative Cytogenetics 15(2): 119-136

DOI: 10.3897/CompCytogen.v15.i2.60649

Authors: Pun Yeesin, Phichaya Buasriyot, Sukhonthip Ditcharoen, Patcharaporn Chaiyasan, Chatmongkon Suwannapoom, Sippakorn Juntaree, Sitthisak Jantarat, Sucheela Talumphai, Marcelo de Bello Cioffi, Thomas Liehr, Alongklod Tanomtong, Weerayuth Supiwong

Abstract: Karyotypes of four catfishes of the genus Mystus Scopoli, 1777 (family Bagridae), M. atrifasciatus Fowler, 1937, M. mysticetus Roberts, 1992, M. singaringan (Bleeker, 1846) and M. wolffii (Bleeker, 1851), were analysed by conventional and Ag-NOR banding as well as fluorescence in situ hybridization (FISH) techniques. Microsatellite d(GC)15, d(CAA)10, d(CAT)10 and d(GAA)10 repeat probes were applied in FISH. The obtained data revealed that the four studied species have different chromosome complements. The diploid chromosome numbers (2n) and the fundamental numbers (NF) range between 52 and 102, 54 and 104, 56 and 98, or 58 and 108 in M. mysticetus, M. atrifasciatus, M. singaringan or M. wolffii, respectively. Karyotype formulae of M. mysticetus, M. atrifasciatus, M. singaringan and M. wolffii are 24m+26sm+4a, 26m+24sm+2a, 24m+18sm+14a and 30m+22sm+6a, respectively. A single pair of NORs was identified adjacent to the telomeres of the short arm of chromosome pairs 3 (metacentric) in M. atrifasciatus, 20 (submetacentric) in M. mysticetus, 15 (submetacentric) in M. singaringan, and 5 (metacentric) in M. wolffii. The d(GC)15, d(CAA)10, d(CAT)10 and d(GAA)10 repeats were abundantly distributed in species-specific patterns. Overall, we present a comparison of cytogenetic and molecular cytogenetic patterns of four species from genus Mystus providing insights into their karyotype diversity in the genus.

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Research Article Mon, 26 Apr 2021 21:57:42 +0300
Cytogenetic analysis of Hypomasticus copelandii and H. steindachneri: relevance of cytotaxonomic markers in the Anostomidae family (Characiformes) https://compcytogen.pensoft.net/article/61957/ Comparative Cytogenetics 15(1): 65-76

DOI: 10.3897/compcytogen.v15.i1.61957

Authors: Filipe Schitini Salgado, Marina Souza Cunha, Silvana Melo, Jorge Abdala Dergam

Abstract: Recent phylogenetic hypotheses within Anostomidae, based on morphological and molecular data, resulted in the description of new genera (Megaleporinus Ramirez, Birindelli et Galetti, 2017) and the synonymization of others, such as the reallocation of Leporinus copelandii Steindachner, 1875 and Leporinus steindachneri Eigenmann, 1907 to Hypomasticus Borodin, 1929. Despite high levels of conservatism of the chromosomal macrostructure in this family, species groups have been corroborated using banding patterns and the presence of different sex chromosome systems. Due to the absence of cytogenetic studies in H. copelandii (Steindachner, 1875) and H. steindachneri (Eigenmann, 1907), the goal of this study was to characterize their karyotypes and investigate the presence/absence of sex chromosome systems using different repetitive DNA probes. Cytogenetic techniques included: Giemsa staining, Ag-NOR banding and FISH using 18S and 5S rDNA probes, as well as microsatellite probes (CA)15 and (GA)15. Both species had 2n = 54, absence of heteromorphic sex chromosomes, one chromosome pair bearing Ag-NOR, 18S and 5S rDNA regions. The (CA)15 and (GA)15 probes marked mainly the subtelomeric regions of all chromosomes and were useful as species-specific chromosomal markers. Our results underline that chromosomal macrostructure is congruent with higher systematic arrangements in Anostomidae, while microsatellite probes are informative about autapomorphic differences between species.

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Research Article Wed, 10 Mar 2021 17:33:21 +0200
Corrigenda: Cytogenetic markers as a tool for characterization of hybrids of Astyanax Baird & Girard, 1854 and Hyphessobrycon Eigenmann, 1907. Comparative Cytogenetics 14(2): 231–242. https://doi.org/10.3897/CompCytogen.v14i2.49513 https://compcytogen.pensoft.net/article/56080/ Comparative Cytogenetics 14(4): 639-643

DOI: 10.3897/CompCytogen.v14i4.56080

Authors: Caio Augusto Gomes Goes, Sandro Natal Daniel, Lucas Henrique Piva, George Shigueki Yasui, Roberto Ferreira Artoni, Diogo Teruo Hashimoto, Fausto Foresti, Fábio Porto-Foresti

Abstract: Astyanax Baird et Girard, 1854, is one of the largest genera in the family Characidae and comprises 177 valid species. This genus has been the focus of cytogenetic studies primarily owing to the presence of B chromosomes and high karyotypic diversity among different populations. The intense genetic variability in Astyanax is one of the factors responsible for the occurrence of species complexes, which are groups (1) with certain difficulties in establishing common genetic pools or (2) belonging to different cryptic species. To evaluate cytogenetic marker inheritance and the possibility of the identification of these hybrids, this study aimed to describe cytogenetic hybrids from three strains of species of the genera Astyanax and Hyphessobrycon Eigenmann, 1908. A. lacustris Lütken, 1875, A. schubarti Britski, 1964, A. fasciatus Cuvier, 1819, and H. anisitsi Eigenmann, 1907 were used to generate three hybrid lineages. The diploid number, heterochromatin sites, and ribosomal genes (18S and 5S rDNA) of the parental strains and the hybrids were analyzed. The results indicated that the three hybrid lineages had cytogenetic markers of both parents, presenting Mendelian inheritance. However, differences in distribution of heterochromatic blocks were observed between the hybrids and the parent strains. Our results allowed the identification of the hybrid strains based on the cytogenetic markers applied, reinforcing the efficiency of cytogenetic markers as tools for identification and indicating that such events may increase the karyotypic diversity in the genera Astyanax and Hyphessobrycon.

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Corrigenda Tue, 29 Dec 2020 11:18:21 +0200
Comparative karyotype study of three Cyprinids (Cyprinidae, Cyprininae) in Thailand by classical cytogenetic and FISH techniques https://compcytogen.pensoft.net/article/54428/ Comparative Cytogenetics 14(4): 597-612

DOI: 10.3897/CompCytogen.v14i4.54428

Authors: Sumalee Phimphan, Patcharaporn Chaiyasan, Chatmongkon Suwannapoom, Montri Reungsing, Sippakorn Juntaree, Alongklod Tanomtong, Weerayuth Supiwong

Abstract: Three species of ornamental fishes in the subfamily Cyprininae (family Cyprinidae) namely, Epalzeorhynchos frenatum (Fowler, 1934), Puntigrus partipentazona (Fowler, 1934), Scaphognathops bandanensis Boonyaratpalin et Srirungroj, 1971 were studied by classical cytogenetic and fluorescent in situ hybridization (FISH) techniques. Chromosomes were directly prepared from kidney tissues and stained by using conventional and Ag-NOR banding techniques. Microsatellite d(CA)15 and d(CGG)10 probes were hybridized to the chromosomes of three cyprinids. The results show that the three cyprinid species share the same diploid number as 2n=50 but there are differences in the fundamental number (NF) and karyotypes i.e. E. frenatum: NF = 78, 18m+10sm+10st+12a; P. partipentazona: NF = 80, 6m+24sm+14st+6a; S. bandanensis: NF = 66, 4m+12sm+34a. NOR positive masks were observed at the regions adjacent to the telomere of the short arm of the chromosome pairs 10 (submetacentric) and 1 (metacentric) in E. frenatum and P. partipentazona, respectively whereas those were revealed at telomeric regions of the long arm of the chromosome pair 9 (acrocentric) in S. bandanensis. The mapping of d(CA)15 and d(CGG)10 microsatellites shown that hybridization signals are abundantly distributed in telomeric regions of several pairs except d(CA)15 repeats in S. bandanensis, which are distributed throughout all chromosomes and d(CGG)10 repeats in P. partipentazona display the high accumulation only in the first chromosome pair.

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Research Article Tue, 22 Dec 2020 13:30:55 +0200
Comparative cytogenetic of six species of Amazonian Peacock bass (Cichla, Cichlinae): intrachromosomal variations and genetic introgression among sympatric species https://compcytogen.pensoft.net/article/55279/ Comparative Cytogenetics 14(3): 437-451

DOI: 10.3897/CompCytogen.v14i3.55279

Authors: Janice Quadros, Alex M. V. Ferreira, Patrik F. Viana, Leandro Marajó, Ezequiel Oliveira, Efrem Ferreira, Eliana Feldberg

Abstract: Cytogenetic data for the genus Cichla Bloch et Schneider, 1801 are still very limited, with only four karyotype descriptions to date. The sum of the available cytogenetic information for Cichla species, points to a maintenance of the diploid number of 48 acrocentric chromosomes, considered a typical ancestral feature in cichlids. In the current study, we performed molecular and classical cytogenetic analyses of the karyotype organization of six species of Cichla, the earliest-diverging genus of Neotropical cichlids. We cytogenetically analysed Cichla kelberi Kullander et Ferreira, 2006, Cichla monoculus Agassiz, 1831, Cichla piquiti Kullander et Ferreira, 2006, Cichla temensis Humboldt, 1821, Cichla vazzoleri Kullander et Ferreira, 2006 and Cichla pinima Kullander et Ferreira, 2006, including three individuals that showed mixed morphological characteristics, likely from different species, suggesting they were hybrid individuals. All individuals analysed showed 2n = 48 acrocentric chromosomes, with centromeric heterochromatic blocks on all chromosomes and a terminal heterochromatic region on the q arm of the 2nd pair. Mapping 18S rDNA gave hybridization signals, correlated with the nucleolus organizer regions, on the 2nd pair for all analyzed individuals. However, we found distinct patterns for 5S rDNA: interstitially at the proximal position on 6th pair of four species (C. kelberi, C. pinima, C. piquiti and C. vazzoleri), and on the distal of the 4th pair in two (C. monoculus and C. temensis). Accordingly, we present here new data for the genus and discuss the evolutionary trends in the karyotype of this group of fish. In addition, we provide data that supports the occurrence of hybrid individuals in the Uatumã River region, mainly based on 5S rDNA mapping.

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Research Article Thu, 17 Sep 2020 12:25:12 +0300
First cytogenetic information for five Nilotic elephantfishes and a problem of ancestral karyotype of the family Mormyridae (Osteoglossiformes) https://compcytogen.pensoft.net/article/52727/ Comparative Cytogenetics 14(3): 387-397

DOI: 10.3897/CompCytogen.14i3.52727

Authors: Sergey Simanovsky, Dmitry Medvedev, Fekadu Tefera, Alexander Golubtsov

Abstract: The elephantfish family Mormyridae is the most diverse lineage of the primitive teleostean clade Osteoglossomorpha distributed in inland waters of all continents except Antarctica and Europe. The family Mormyridae is endemic to Africa and includes 22 genera and almost 230 species. The evolutionary radiation of mormyrids most probably should be attributed to their capability of both generating and receiving weak electric signals. Up-to-date cytogenetic studies have revealed substantial karyotype differentiation among the nine investigated elephantfish species and genera (a single species studied per each genus). In the present study, karyotypes of five species representing five mormyrid genera (four unexplored ones) collected from the White Nile system in southwestern Ethiopia are described for the first time. The results show substantial variety of the diploid chromosome and fundamental numbers: 2n = 48 and FN = 54 in Brevimyrus niger (Günther, 1866), 2n = 50 and FN = 72 in Cyphomyrus petherici (Boulenger, 1898), 2n = 50 and FN = 78 in Hippopotamyrus pictus (Marcusen, 1864), 2n = 50 and FN = 76 in Marcusenius cyprinoides (Linnaeus, 1758), 2n = 52 and FN = 52 in Mormyrops anguilloides (Linnaeus, 1758). Karyotype structure in the latter species seems to be close to the ancestral condition for the family. This hypothesis is discussed in the light of available data on karyotype diversity and phylogeny of mormyrids.

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Research Article Wed, 19 Aug 2020 20:18:37 +0300
Cytogenetic characterization, rDNA mapping and quantification of the nuclear DNA content in Seriolella violacea Guichenot, 1848 (Perciformes, Centrolophidae) https://compcytogen.pensoft.net/article/53087/ Comparative Cytogenetics 14(3): 319-328

DOI: 10.3897/CompCytogen.v14i3.53087

Authors: Cristian Araya-Jaime, Claudio Palma-Rojas, Elisabeth Von Brand, Alfonso Silva

Abstract: Seriolella violacea Guichenot, 1848 is an important component of the fish fauna of the Chilean coast and is of great economic interest. Cytogenetic information for the family Centrolophidae is lacking and the genomic size of five of the twenty-eight species described for this family are is barely known. This study aimed to describe for the first time the karyotype structure via classical and molecular cytogenetics analysis with the goal of identifying the constitutive heterochromatin distribution, chromosome organization of rDNA sequences and quantification of nuclear DNA content. The karyotype of S. violacea is composed of 48 chromosomes, with the presence of conspicuous blocks of heterochromatin on chromosomal pairs one and two. FISH assay with a 5S rDNA probe, revealed the presence of fluorescent markings on the heterochromatic block of pair one. The 18S rDNA sites are located exclusively on pair two, characterizing this pair as the carrier of the NOR. Finally, the genomic size of S. violacea was estimated at 0.59 pg of DNA as C-value. This work represents the first effort to document the karyotype structure and physical organization of the rDNA sequences in the Seriolella genome, contributing with new information to improve our understanding of chromosomal evolution and genomic organization in marine perciforms.

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Research Article Tue, 14 Jul 2020 12:20:33 +0300
Cytogenetic markers as a tool for characterization of hybrids of Astyanax Baird & Girard, 1854 and Hyphessobrycon Eigenmann, 1907 https://compcytogen.pensoft.net/article/49513/ Comparative Cytogenetics 14(2): 231-242

DOI: 10.3897/CompCytogen.v14i2.49513

Authors: Caio Augusto Gomes Goes, Sandro Natal Daniel, Lucas Henrique Piva, George Shigueki Yasui, Roberto Ferreira Artoni, Diogo Teruo Hashimoto, Fausto Foresti, Fábio Porto-Foresti

Abstract: Astyanax Baird et Girard, 1854, is one of the largest genera in the family Characidae and comprises 177 valid species. This genus has been the focus of cytogenetic studies primarily owing to the presence of B chromosomes and high karyotypic diversity among different populations. The intense genetic variability in Astyanax is one of the factors responsible for the occurrence of species complexes, which are groups (1) with certain difficulties in establishing common genetic pools or (2) belonging to different cryptic species. To evaluate cytogenetic marker inheritance and the possibility of the identification of these hybrids, this study aimed to describe cytogenetic hybrids from three strains of species of the genera Astyanax and Hyphessobrycon Eigenmann, 1908. A. lacustris Lütken, 1875, A. schubarti Britski, 1964, A. fasciatus Cuvier, 1819, and H. anisitsi Eigenmann, 1907 were used to generate three hybrid lineages. The diploid number, heterochromatin sites, and ribosomal genes (18S and 5S rDNA) of the parental strains and the hybrids were analyzed. The results indicated that the three hybrid lineages had cytogenetic markers of both parents, presenting Mendelian inheritance. However, differences in distribution of heterochromatic blocks were observed between the hybrids and the parent strains. Our results allowed the identification of the hybrid strains based on the cytogenetic markers applied, reinforcing the efficiency of cytogenetic markers as tools for identification and indicating that such events may increase the karyotypic diversity in the genera Astyanax and Hyphessobrycon.

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Research Article Wed, 27 May 2020 11:24:10 +0300
Interspecific cytogenetic relationships in three Acestrohynchus species (Acestrohynchinae, Characiformes) reveal the existence of possible cryptic species https://compcytogen.pensoft.net/article/33483/ Comparative Cytogenetics 14(1): 27-42

DOI: 10.3897/CompCytogen.v14i1.33483

Authors: Alber Sousa Campos, Ramon Marin Favarato, Eliana Feldberg

Abstract: 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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Research Article Wed, 15 Jan 2020 21:16:30 +0200
Karyotype and chromosomal characteristics of rDNA of Cobitis strumicae Karaman, 1955 (Teleostei, Cobitidae) from Lake Volvi, Greece https://compcytogen.pensoft.net/article/28068/ Comparative Cytogenetics 12(4): 483-491

DOI: 10.3897/CompCytogen.v12i4.28068

Authors: Eva Hnátková, Costas Triantaphyllidis, Catherine Ozouf-Costaz, Lukáš Choleva, Zuzana Majtánová, Joerg Bohlen, Petr Ráb

Abstract: The karyotype of Greek cobitid fish Cobitis strumicae Karaman, 1955, from Lake Volvi, Greece, a representative of one of its two major intraspecific phylogenetic lineages, was analysed by means of sequential Giemsa-staining, C-banding, silver-staining, CMA3 fluorescence banding and also by in situ hybridization (FISH) with rDNA probe. The diploid chromosome number was 2n = 50, karyotype composed of 10 pairs of metacentric to submetacentric and 15 pairs of subtelocentric to acrocentric chromosomes. The nucleolus organizer regions (NORs) as revealed by Ag- and CMA3 staining and FISH were situated in the telomeric region of the fourth submetacentric chromosome pair. The chromosomes contained very low content of C-positive heterochromatin. No heteromorphic sex chromosomes were detected. This first karyotype report for any species of lineage Bicanestrinia Băcescu, 1962 shows a simple karyotype dominated by acrocentric chromosomes and possessing single NOR-bearing chromosome pair. Cytotaxonomic implications of this finding for the taxonomy of the genus Cobitis Linnaeus, 1758 are further discussed.

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Research Article Fri, 16 Nov 2018 15:06:17 +0200
Extensive karyotype variability of African fish genus Nothobranchius (Cyprinodontiformes) https://compcytogen.pensoft.net/article/25092/ Comparative Cytogenetics 12(3): 387-402

DOI: 10.3897/CompCytogen.v12i3.25092

Authors: Eugene Krysanov, Tatiana Demidova

Abstract: Karyotypes of 65 species of the genus Nothobranchius Peters, 1868 were reviewed and of those 35 examined first time. The results of present study have shown that fishes of the genus Nothobranchius possessed highly diverse karyotypes. The diploid chromosome number (2n) ranged from 16 to 50. The most frequent 2n was 2n = 36 (in 35 species) while the second one 2n = 38 (in 13 species). Proportion of biarmed chromosomes varied from 0 to 95% between species. Diploid chromosome number variability apparently exists as a result of chromosomal fusions or fissions and extensive karyotypic formula alterations promoting by inversions. Multiple sex chromosomes of system X1X1X2X2/X1X2Y type were found only in karyotypes of 5 species. The extensive karyotype variability, unusual for teleosts, of genus Nothobranchius can be likely associated with the characteristics of its life cycle and inhabiting under unstable environment of East African savannah temporal pools.

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Research Article Mon, 10 Sep 2018 18:14:23 +0300
Karyotypic variation in the long-whiskered catfish Pimelodus blochii Valenciennes, 1840 (Siluriformes, Pimelodidae) from the lower Tapajós, Amazonas and Trombetas Rivers https://compcytogen.pensoft.net/article/22590/ Comparative Cytogenetics 12(3): 285-298

DOI: 10.3897/CompCytogen.v12i3.22590

Authors: Ivanny Coelho da Fonseca, Luan Aércio Melo Maciel, Frank Raynner Vasconcelos Ribeiro, Luís Reginaldo Ribeiro Rodrigues

Abstract: The genus Pimelodus LaCépède, 1803 comprises 35 formally recognized species distributed along the major neotropical river basins. Despite conservatism in diploid number with 2n=56, an intense variation of chromosomal morphology (karyotypic formula) has been documented in Pimelodus species. In the present study, we analyzed karyotypes of 20 specimens, identified as Pimelodus blochii Valenciennes, 1840 and collected from the lower courses of the Tapajós, Amazonas and Trombetas Rivers. The karyotypes were characterized by Giemsa conventional staining, C-banding, silver staining (Ag-NOR) and fluorescent in situ hybridization (FISH) with 5S and 18S rDNA probes. The karyotypes showed 2n=56 chromosomes in fish from the Tapajós River. In contrast, fish from the Amazonas and Trombetas Rivers had 2n=58. The nucleolus organizing regions were labeled on the short arm of an acrocentric chromosome as demonstrated by silver staining and FISH. Signals for 18S and 5S rDNA were co-localized on one chromosome pair. Our results demonstrate karyotypic divergence between Tapajós and Amazonas-Trombetas populations of P. blochii, interpreted as supporting the existence of a species complex in this taxon.

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Research Article Thu, 2 Aug 2018 09:52:36 +0300
Differential hypomethylation of the repetitive Tol2/Alu-rich sequences in the genome of Bodianus species (Labriformes, Labridae) https://compcytogen.pensoft.net/article/21830/ Comparative Cytogenetics 12(2): 145-162

DOI: 10.3897/CompCytogen.v12i2.21830

Authors: Clóvis C. Motta-Neto, André Marques, Gideão W.W.F. Costa, Marcelo B. Cioffi, Luiz A.C. Bertollo, Rodrigo X. Soares, Kátia C. Scortecci, Roberto F. Artoni, Wagner F. Molina

Abstract: Representatives of the order Labriformes show karyotypes of extreme conservatism together with others with high chromosomal diversification. However, the cytological characterization of epigenetic modifications remains unknown for the majority of the species. In the family Labridae, the most abundant fishes on tropical reefs, the genomes of the genus Bodianus Bloch, 1790 have been characterized by the occurrence of a peculiar chromosomal region, here denominated BOD. This region is exceptionally decondensed, heterochromatic, argentophilic, GC-neutral and, in contrast to classical secondary constrictions, shows no signals of hybridization with 18S rDNA probes. In order to characterize the BOD region, the methylation pattern, the distribution of Alu and Tol2 retrotransposons and of 18S and 5S rDNA sites, respectively, were analyzed by Fluorescence In Situ Hybridization (FISH) on metaphase chromosomes of two Bodianus species, B. insularis Gomon & Lubbock, 1980 and B. pulchellus (Poey, 1860). Immunolocalization of the 5-methylcytosine revealed hypermethylated chromosomal regions, dispersed along the entire length of the chromosomes of both species, while the BOD regions exhibited a hypomethylated pattern. Hypomethylation of the BOD region is associated with the precise co-location of Tol2 and Alu elements, suggesting their active participation in the regulatory epigenetic process. This evidence underscores a probable differential methylation action during the cell cycle, as well as the role of Tol2/Alu elements in functional processes of fish genomes.

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Research Article Wed, 28 Mar 2018 09:07:19 +0300
Chromosomal organization of four classes of repetitive DNA sequences in killifish Orestias ascotanensis Parenti, 1984 (Cyprinodontiformes, Cyprinodontidae) https://compcytogen.pensoft.net/article/11729/ Comparative Cytogenetics 11(3): 463-475

DOI: 10.3897/compcytogen.v11i3.11729

Authors: Cristian Araya-Jaime, Natalia Lam, Irma Vila Pinto, Marco A. Méndez, Patricia Iturra

Abstract: Orestias Valenciennes, 1839 is a genus of freshwater fish endemic to the South American Altiplano. Cytogenetic studies of these species have focused on conventional karyotyping. The aim of this study was to use classical and molecular cytogenetic methods to identify the constitutive heterochromatin distribution and chromosome organization of four classes of repetitive DNA sequences (histone H3 DNA, U2 snRNA, 18S rDNA and 5S rDNA) in the chromosomes of O. ascotanensis Parenti, 1984, an endemic species restricted to the Salar de Ascotán in the Chilean Altiplano. All individuals analyzed had a diploid number of 48 chromosomes. C-banding identified constitutive heterochromatin mainly in the pericentromeric region of most chromosomes, especially a GC-rich heterochromatic block of the short arm of pair 3. FISH assay with an 18S probe confirmed the location of the NOR in pair 3 and revealed that the minor rDNA cluster occurs interstitially on the long arm of pair 2. Dual FISH identified a single block of U2 snDNA sequences in the pericentromeric regions of a subtelocentric chromosome pair, while histone H3 sites were observed as small signals scattered in throughout the all chromosomes. This work represents the first effort to document the physical organization of the repetitive fraction of the Orestias genome. These data will improve our understanding of the chromosomal evolution of a genus facing serious conservation problems.

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Research Article Tue, 25 Jul 2017 11:38:05 +0300
B chromosome dynamics in Prochilodus costatus (Teleostei, Characiformes) and comparisons with supernumerary chromosome system in other Prochilodus species https://compcytogen.pensoft.net/article/12784/ Comparative Cytogenetics 11(2): 393-403

DOI: 10.3897/CompCytogen.v11i2.12784

Authors: Silvana Melo, Ricardo Utsunomia, Manolo Penitente, Patrícia Elda Sobrinho-Scudeler, Fábio Porto-Foresti, Claudio Oliveira, Fausto Foresti, Jorge Abdala Dergam

Abstract: Within the genus Prochilodus Agassiz, 1829, five species are known to carry B chromosomes, i.e. chromosomes beyond the usual diploid number that have been traditionally considered as accessory for the genome. Chromosome microdissection and mapping of repetitive DNA sequences are effective tools to assess the DNA content and allow a better understanding about the origin and composition of these elements in an array of species. In this study, a novel characterization of B chromosomes in Prochilodus costatus Valenciennes, 1850 (2n=54) was reported for the first time and their sequence complementarity with the supernumerary chromosomes observed in Prochilodus lineatus (Valenciennes, 1836) and Prochilodus argenteus Agassiz, 1829 was investigated. The hybridization patterns obtained with chromosome painting using the micro B probe of P. costatus and the satDNA SATH1 mapping made it possible to assume homology of sequences between the B chromosomes of these congeneric species. Our results suggest that the origin of B chromosomes in the genus Prochilodus is a phylogenetically old event.

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Short Communication Thu, 1 Jun 2017 12:29:20 +0300
Chromosomal stasis in distinct families of marine Percomorpharia from South Atlantic https://compcytogen.pensoft.net/article/11942/ Comparative Cytogenetics 11(2): 299-307

DOI: 10.3897/CompCytogen.v11i2.11942

Authors: Fabilene Gomes Paim, Leandro Aragão da Hora Almeida, Paulo Roberto Antunes de Mello Affonso, Patrícia Elda Sobrinho-Scudeler, Claudio Oliveira, Débora Diniz

Abstract: The weakness of physical barriers in the marine environment and the dispersal potential of fish populations have been invoked as explanations of the apparent karyotype stasis of marine Percomorpha, but several taxa remain poorly studied cytogenetically. To increase the chromosomal data in this fish group, we analyzed cytogenetically three widespread Atlantic species from distinct families: Chaetodipterus faber Broussonet, 1782 (Ephippidae), Lutjanus synagris Linnaeus, 1758 (Lutjanidae) and Rypticus randalli Courtenay, 1967 (Serranidae). The three species shared a karyotype composed of 2n=48 acrocentric chromosomes, single nucleolus organizer regions (NORs) and reduced amounts of centromeric heterochromatin. A single NOR-bearing pair was identified in all species by physical mapping of 18S rDNA while non-syntenic 5S rRNA genes were located at centromeric region of a single pair. The similar karyotypic macrostructure observed in unrelated groups of Percomorpharia reinforces the conservative karyoevolution of marine teleosteans. Nonetheless, the species could be differentiated based on the pair bearing ribosomal cistrons, revealing the importance of microstructural analyses in species with symmetric and stable karyotypes.

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Short Communication Thu, 4 May 2017 17:45:44 +0300
The Mugil curema species complex (Pisces, Mugilidae): a new karyotype for the Pacific white mullet mitochondrial lineage https://compcytogen.pensoft.net/article/11579/ Comparative Cytogenetics 11(2): 225-237

DOI: 10.3897/CompCytogen.v11i2.11579

Authors: Mauro Nirchio, Claudio Oliveira, Zoila R. Siccha-Ramirez, Viviani F. de Sene, Luciana Sola, Valentina Milana, Anna Rita Rossi

Abstract: Recent molecular phylogenetic analyses have shown that the Mugil curema Valenciennes, 1836 species complex includes M. incilis Hancock, 1830, M. thoburni (Jordan & Starks, 1896) and at least four “M. curema” mitochondrial lineages, considered as cryptic species. The cytogenetic data on some representatives of the species complex have shown a high cytogenetic diversity. This research reports the results of cytogenetic and molecular analyses of white mullet collected in Ecuador. The analyzed specimens were molecularly assigned to the Mugil sp. O, the putative cryptic species present in the Pacific Ocean and showed a 2n = 46 karyotype, which is composed of 2 metacentric and 44 subtelocentric/acrocentric chromosomes. This karyotype is different from the one described for M. incilis (2n = 48) and from those of the two western Atlantic lineages Mugil curema (2n = 28), and Mugil margaritae (2n = 24). Data suggest the need for a morphological analysis to assign a species name to this Pacific lineage.

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Research Article Fri, 7 Apr 2017 11:25:44 +0300
Variability and evolutionary implications of repetitive DNA dynamics in genome of Astyanax scabripinnis (Teleostei, Characidae) https://compcytogen.pensoft.net/article/11149/ Comparative Cytogenetics 11(1): 143-162

DOI: 10.3897/CompCytogen.v11i1.11149

Authors: Patrícia Barbosa, Eliza Viola Leal, Maelin da Silva, Mara Cristina de Almeida, Orlando Moreira-Filho, Roberto Ferreira Artoni

Abstract: DNA sequences of multiple copies help in understanding evolutionary mechanisms, genomic structures and karyotype differentiation. The current study investigates the organization and distribution of different repetitive DNA in the standard complement and B chromosomes in Astyanax scabripinnis (Jenyns, 1842) chromosomes from three allopatric populations in Campos do Jordão region, São Paulo State, Brazil. The location of microsatellite sequences showed different chromosome distribution between Lavrinha Farm Stream (LFS) and Lake of Pedalinho (LP) populations. However, the karyotype of these populations basically followed the pattern of dispersed distribution in the A complement, conspicuous in telomeric/interstitial regions and preferential accumulation in the B chromosome. The B chromosome showed heterogeneous location of microsatellite probes CA, CAC and GA. The H3 and H4 histone genes were isolated from the total genome of the species and then the chromosomal mapping was performed by fluorescence in situ hybridization (FISH). The FISH signals showed high similarity for the probes H3 and H4 mapping in genomes of the populations analyzed. The sequences (GATA)n revealed a sex-specific trend between the chromosomal location in males and females at (LFS) and (LP) populations. Although species that comprise the Astyanax scabripinnis complex do not have morphologically differentiated sex chromosomes, the preferential GATA location – sex-associated – may represent a sex chromosome in differentiation.

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Research Article Mon, 6 Mar 2017 12:43:57 +0200
Chromosome mapping of a Tc1-like transposon in species of the catfish Ancistrus https://compcytogen.pensoft.net/article/10519/ Comparative Cytogenetics 11(1): 65-79

DOI: 10.3897/CompCytogen.v11i1.10519

Authors: Keteryne Rodrigues da Silva, Sandra Mariotto, Liano Centofante, Patricia Pasquali Parise-Maltempi

Abstract: The Tc1 mariner element is widely distributed among organisms and have been already described in different species of fish. The genus Ancistrus (Kner, 1854) has 68 nominal species and is part of an interesting taxonomic and cytogenetic group, as well as presenting a variation of chromosome number, ranging from 2n=34 to 54 chromosomes, and the existence of simple and multiple sex chromosome system and the occurrence of chromosomal polymorphisms involving chromosomes that carry the nucleolus organizer region. In this study, a repetitive element by restriction enzyme, from Ancistrus sp.1 “Flecha” was isolated, which showed similarity with a transposable element Tc1-mariner. Its chromosomal location is distributed in heterochromatic regions and along the chromosomal arms of all specimens covered in this study, confirming the pattern dispersed of this element found in other studies carried out with other species. Thus, this result reinforces the hypothesis that the sequence AnDraI is really a dispersed element isolated. As this isolated sequence showed the same pattern in all species which have different sex chromosomes systems, including in all sex chromosomes, we could know that it is not involved in sex chromosome differentiation.

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Research Article Fri, 20 Jan 2017 16:25:55 +0200
Origin of B chromosomes in Characidium alipioi (Characiformes, Crenuchidae) and its relationship with supernumerary chromosomes in other Characidium species https://compcytogen.pensoft.net/article/10886/ Comparative Cytogenetics 11(1): 81-95

DOI: 10.3897/CompCytogen.v11i1.10886

Authors: Érica Alves Serrano, Ricardo Utsunomia, Patrícia Sobrinho Scudeller, Claudio Oliveira, Fausto Foresti

Abstract: B chromosomes are apparently dispensable components found in the genomes of many species that are mainly composed of repetitive DNA sequences. Among the numerous questions concerning B chromosomes, the origin of these elements has been widely studied. To date, supernumerary chromosomes have been identified in approximately 60 species of fish, including species of the genus Characidium Reinhardt, 1867 in which these elements appear to have independently originated. In this study, we used molecular cytogenetic techniques to investigate the origin of B chromosomes in a population of Characidium alipioi Travassos, 1955 and determine their relationship with the extra chromosomes of other species of the genus. The results showed that the B chromosomes of C. alipioi had an intraspecific origin, apparently originated independently in relation to the B chromosomes of C. gomesi Travassos, 1956 C. pterostictum Gomes, 1947 and C. oiticicai Travassos, 1967, since they do not share specific DNA sequences, as well as their possible ancestral chromosomes and belong to different phylogenetic clades. The shared sequences between the supernumerary chromosomes and the autosommal sm pair indicate the origin of these chromosomes.

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Research Article Fri, 20 Jan 2017 16:25:27 +0200
First report of B chromosomes in three neotropical thorny catfishes (Siluriformes, Doradidae) https://compcytogen.pensoft.net/article/10496/ Comparative Cytogenetics 11(1): 55-64

DOI: 10.3897/CompCytogen.v11i1.10496

Authors: Fábio Hiroshi Takagui, Ana Lucia Dias, José Luís Olivan Birindelli, Ana Claudia Swarça, Renata da Rosa, Roberto Laridondo Lui, Alberto Sergio Fenocchio, Lucia Giuliano-Caetano

Abstract: The family Doradidae (Siluriformes) is an important group of fishes endemic to freshwater ecosystems in South America. Some cytogenetic studies have been conducted focused on the group; however, there are no reports on the occurrence of B chromosomes for the family. In this paper the chromosomal characteristics of Platydoras armatulus (Valenciennes, 1840), Pterodoras granulosus (Valenciennes, 1821) and Ossancora punctata (Kner, 1855) were investigated through classical cytogenetics approaches. The conventional staining reveals 2n=58 in Platydoras armatulus and Pterodoras granulosus, however with distinct karyotypic formulae, possibly originated by pericentric inversions. In Ossancora punctata a derivate karyotype was described with 2n=66 and predominance of acrocentric chromosomes. The C banding pattern was resolutive in discriminating the three species, being considered an important cytotaxonomic marker. All species showed B chromosomes totally heterochromatic with non-Mendelian segregation during meiosis and low frequencies in mitotic cells. The probably origin of these additional elements was through fragmentations of chromosomes of the standard complement, which occurred recently and independently in these three species. The diploid number observed in O. punctata is an evidence of centric fusions and up to the moment it is the highest diploid number reported for Doradidae.

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Research Article Mon, 9 Jan 2017 13:23:04 +0200
Cytogenetic characterization of Hoplias malabaricus (Bloch, 1794) from the Ctalamochita River (Córdoba, Argentina): first evidence for southernmost populations of this species complex and comments on its biogeography https://compcytogen.pensoft.net/article/10262/ Comparative Cytogenetics 11(1): 15-28

DOI: 10.3897/CompCytogen.v11i1.10262

Authors: Diego Javier Grassi, Ana Cláudia Swarça, Jorge Abdala Dergam, Maria Cristina Pastori, Alberto Sergio Fenocchio

Abstract: Hoplias malabaricus (Bloch, 1794), a predatory freshwater fish with a wide distribution throughout South America, represents a species complex with seven well characterized karyomorphs at the cytogenetic level. Although this species has been extensively studied in several Brazilian basins, data are still scarce for hydrographic systems from other South American countries. This study aims to characterize cytogenetically the Hoplias malabaricus populations from the Argentinean Central Region, close to the southernmost distribution of this species complex. A total of 32 specimens from the Ctalamochita River, a tributary of Lower Paraná Basin located in the province of Córdoba, were analyzed using cytogenetic techniques (Giemsa staining, C- and Ag-NOR banding and fluorescent in situ hybridization with 18S rDNA). All the specimens showed diploid number 2n=42, chromosomic formula 22m + 20sm and absence of sexual chromosomes. Thus, the analyzed populations belong to the karyomorph named A. These populations showed a remarkable degree of divergence in their cytogenetic traits such as karyotypic formula, C-banding, NORs and 18S rDNA patterns for Hoplias malabaricus from other populations bearing the same karyomorph in the Middle and Upper Paraná Basin. These findings are consistent with molecular data from a recent study (where specimens collected in the present work were included), which indicate a closer phylogenetic relationship of Hoplias malabaricus populations from the Ctalamochita River with those from the Uruguay basin and the coastal regions of South Brazil than with populations from the Middle and Upper Paraná Basin. Overall, these pieces of evidence highlight the distinctive features of Hoplias malabaricus from the Ctalamochita River, and also reveal a complex history of dispersion of these populations. The present work is the first to provide cytogenetic information and include some phylogeographic aspects of Hoplias malabaricus populations living in close proximity to the southernmost extreme of its distribution area. Therefore, this study expands significantly upon the previously known geographical coverage for karyomorph A and contributes to a better understanding of the karyotypic diversification within this species complex.

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Research Article Mon, 9 Jan 2017 12:48:44 +0200
First cytogenetic analysis of Ichthyoelephas humeralis (Günther, 1860) by conventional and molecular methods with comments on the karyotypic evolution in Prochilodontidae https://compcytogen.pensoft.net/article/9858/ Comparative Cytogenetics 10(4): 615-624

DOI: 10.3897/CompCytogen.v10i4.9858

Authors: Mauro Nirchio Tursellino, Duílio Mazzoni Zerbinato de Andrade Silva, César Quezada Abad, Wilmer Arnoldo Moreira Blacio, Omar Rogerio Sánchez Romero, Claudio Oliveira

Abstract: We used conventional cytogenetic techniques (Giemsa, C-banding, Ag-NOR), and fluorescent in situ hybridization (FISH) with 5S and 18S rDNA probes to investigate the karyotype and cytogenetic characteristics of Ichthyoelephas humeralis (Günther, 1860) from Ecuador. The specimens studied have a karyotype with 2n=54 biarmed chromosomes (32 M + 22 SM) and C-positive heterochromatin located on the centromeric, pericentromeric, interstitial, and terminal regions of some chromosomes. The nucleolus organizer regions occurred terminally on the long arm of chromosome pair 2. FISH confirmed the presence of only one 18S rDNA cluster with nonsyntenic localization with the 5S rDNA. Cytogenetic data allow us to refute the earlier morphological hypothesis of a sister relationship between Semaprochilodus Fowler, 1941 and Ichthyoelephas Posada Arango, 1909 and support the molecular proposal that Ichthyoelephas is a sister group to the monophyletic clade containing Prochilodus Agassiz, 1829 and Semaprochilodus.

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Research Article Fri, 18 Nov 2016 18:40:43 +0200
An uncommon co-localization of rDNA 5S with major rDNA clusters in Callichthyidae (Siluriformes): a report case in Corydoras carlae Nijssen & Isbrücker, 1983 https://compcytogen.pensoft.net/article/9507/ Comparative Cytogenetics 10(4): 603-613

DOI: 10.3897/CompCytogen.v10i4.9507

Authors: Rafael Henrique da Rocha, Lucas Baumgätner, Leonardo Marcel Paiz, Vladimir Pavan Margarido, Carlos Alexandre Fernandes, Eder Andre Gubiani

Abstract: Corydoras Lacepède, 1803 is the most specious genus of Corydoradinae subfamily and many of its species are still unknown in relation to molecular cytogenetic markers. However, the diploid number and karyotypic formula were recorded for many species of this group. In current study, we provided the first cytogenetic information of Corydoras carlae Nijssen & Isbrücker, 1983, an endemic fish species from Iguassu River basin, Paraná State, Brazil. The individuals were collected in Florido River, a tributary of Iguassu River and analysed with respect to diploid number, heterochromatin distribution pattern, Ag-NORs and mapping of 5S and 18S ribosomal genes. The karyotype of this species comprises 46 chromosomes arranged in 22m+22sm+2st. The heterochromatin is distributed in centromeric and pericentromeric positions in most of the chromosomes, and also associated with NORs. The Ag-NORs were detected in the terminal position on the long arm of the metacentric pair 6. The double-FISH technique showed that 5S rDNA and 18S rDNA were co-localized in the terminal portion on the long arm of the metacentric pair 6. This condition of co-localization of ribosomal genes in C. carlae seems to represent a marker for this species.

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Research Article Fri, 18 Nov 2016 12:46:29 +0200
Co-located 18S/5S rDNA arrays: an ancient and unusual chromosomal trait in Julidini species (Labridae, Perciformes) https://compcytogen.pensoft.net/article/10227/ Comparative Cytogenetics 10(4): 555-570

DOI: 10.3897/CompCytogen.v10i4.10227

Authors: Karlla Danielle Jorge Amorim, Marcelo de Bello Cioffi, Luiz Antônio Carlos Bertollo, Rodrigo Xavier Soares, Allyson Santos Souza, Gideão Wagner Werneck Félix da Costa, Wagner Franco Molina

Abstract: Wrasses (Labridae) are extremely diversified marine fishes, whose species exhibit complex interactions with the reef environment. They are widely distributed in the Indian, Pacific and Atlantic oceans. Their species have displayed a number of karyotypic divergent processes, including chromosomal regions with complex structural organization. Current cytogenetic information for this family is phylogenetically and geographically limited and mainly based on conventional cytogenetic techniques. Here, the distribution patterns of heterochromatin, GC-specific chromosome regions and Ag-NORs, and the organization of 18S and 5S rDNA sites of the Atlantic species Thalassoma noronhanum (Boulenger, 1890), Halichoeres poeyi (Steindachner, 1867), Halichoeres radiatus (Linnaeus, 1758), Halichoeres brasiliensis (Bloch, 1791) and Halichoeres penrosei Starks, 1913, belonging to the tribe Julidini were analyzed. All the species exhibited 2n=48 chromosomes with variation in the number of chromosome arms among genera. T. noronhanum has 2m+46a, while species of the genus Halichoeres Rüppell, 1835 share karyotypes with 48 acrocentric chromosomes. The Halichoeres species exhibit differences in the heterochromatin distribution patterns and in the number and distribution of 18S and 5S rDNA sites. The occurrence of 18S/5S rDNA syntenic arrangements in all the species indicates a functionally stable and adaptive genomic organization. The phylogenetic sharing of this rDNA organization highlights a marked and unusual chromosomal singularity inside the family Labridae.

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Research Article Fri, 4 Nov 2016 11:39:50 +0200
Divergent karyotypes of the annual killifish genus Nothobranchius (Cyprinodontiformes, Nothobranchiidae) https://compcytogen.pensoft.net/article/9863/ Comparative Cytogenetics 10(3): 439-445

DOI: 10.3897/CompCytogen.v10i3.9863

Authors: Eugene Krysanov, Tatiana Demidova, Bela Nagy

Abstract: Karyotypes of two species of the African annual killifish genus Nothobranchius Peters, 1868, N. brieni Poll, 1938 and Nothobranchius sp. from Kasenga (D.R. Congo) are described. Both species displayed diploid chromosome number 2n = 49/50 for males and females respectively with multiple-sex chromosome system type X1X2Y/X1X1X2X2. The karyotypes of studied species are considerably different from those previously reported for the genus Nothobranchius and similar to the Actinopterygii conservative karyotype.

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Short Communication Fri, 16 Sep 2016 20:42:02 +0300
ZZ/ZW sex chromosome system in the endangered fish Lignobrycon myersi Miranda-Ribeiro, 1956 (Teleostei, Characiformes, Triportheidae) https://compcytogen.pensoft.net/article/8435/ Comparative Cytogenetics 10(2): 245-254

DOI: 10.3897/CompCytogen.v10i2.8435

Authors: Alexandre dos Santos Rodrigues, Aline Souza Medrado, Débora Diniz, Claudio Oliveira, Paulo Roberto Antunes de Mello Affonso

Abstract: Lignobrycon myersi is an endemic fish species from a few coastal rivers in northeastern Brazil. Based on molecular evidence, L. myersi and genera Triportheus Cope, 1872, Agoniates Müller & Troschel, 1845, Clupeacharax Pearson, 1924 and Engraulisoma Castro, 1981 were placed in the family Triportheidae. In the present work, we report the first cytogenetic data for L. myersi to test the hypothesis that Lignobrycon and Triportheus are closely related. Studied specimens presented 2n=52 with 28 metacentric (m), 18 submetacentric (sm) and six subtelocentric (st) chromosomes for males and 27 m, 19 sm and 6 st for females, characterizing a ZZ/ZW sex chromosome system. The Z chromosome corresponds to the largest chromosome in karyotype while the W is about 50% smaller than the Z and largely heterochromatic. Terminal nucleolus organizer regions, GC-rich sites and 18S rDNA signals were detected on pair 14. However, additional 18S rDNA sites were observed in the W chromosome. The 5S rDNA was mainly detected on long arms of pair 7. The apparent synapomorphic chromosomal traits of Triportheus and L. myersi reinforce their close phylogenetic relationship, suggesting that the ZZ/ZW chromosome system in both genera has arisen before cladogenic events.

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Research Article Wed, 18 May 2016 10:13:23 +0300
Evolutionary trends in the family Curimatidae (Characiformes): inferences from chromosome banding https://compcytogen.pensoft.net/article/6316/ Comparative Cytogenetics 10(1): 77-95

DOI: 10.3897/CompCytogen.v10i1.6316

Authors: Tatiane Ramos Sampaio, Larissa Bettin Pires, Natalia Bortolazzi Venturelli, Mariana Campaner Usso, Renata da Rosa, Ana Lúcia Dias

Abstract: The family Curimatidae is a fish group usually considered chromosomally conserved in their diploid number. However, some studies show small changes in the karyotype microstructure, and the presence of B chromosomes, indicating a chromosomal diversification within the group, even if structural changes in the karyotypes are not visible. Few studies associate this trait with an evolutionary pattern within the family. This study aimed to characterize the karyotype, nucleolus organizer regions (NORs), and heterochromatin distribution of six species of Curimatidae of the genera Cyphocharax Fowler, 1906 and Steindachnerina Fowler, 1906: C. voga (Hensel, 1870), C. spilotus (Vari, 1987), C. saladensis (Meinken, 1933), C. modestus (Fernández-Yépez, 1948), S. biornata (Braga et Azpelicueta, 1987) and S. insculpta (Fernández-Yépez, 1948) and contribute data to a better understanding of the mechanisms involved in the chromosomal evolution of this group of fish. All specimens had 2n=54, m-sm, and B microchromosomes. Five species exhibited single NORs, except for S. biornata, which showed a multiple pattern of ribosomal sites. NORs were chromomycin A3 positive (CMA3+) and 4’-6-diamino-2-phenylindole (DAPI-) negative, exhibiting differences in the pair and chromosomal location of each individual of the species. FISH with 5S rDNA probe revealed sites in the pericentrometic position of a pair of chromosomes of five species. However, another site was detected on a metacentric chromosome of C. spilotus. Heterochromatin distributed both in the pericentromeric and some terminal regions was revealed to be CMA3+/DAPI-. These data associated with the previously existing ones confirm that, although Curimatidae have a very conservative karyotype macrostructure, NORs and heterochromatin variability are caused by mechanisms of chromosome alterations, such as translocations and/or inversions, leading to the evolution and diversification of this group of fish.

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Research Article Fri, 22 Jan 2016 21:33:45 +0200
First cytogenetic report in Cichlasoma sanctifranciscense Kullander, 1983 (Perciformes, Cichlidae) from northeastern Brazil with inferences on chromosomal evolution of Cichlasomatini https://compcytogen.pensoft.net/article/5562/ Comparative Cytogenetics 9(4): 671-681

DOI: 10.3897/CompCytogen.v9i4.5562

Authors: Leandro Argôlo, Paulo Roberto Affonso

Abstract: Even though genetic aspects of some cichlids have been widely studied over the last decades, little is known about the genomic structure of Cichlidae when compared to the large number of species in the family. In this paper, the first chromosomal data for Cichlasoma sanctifranciscense Kullander, 1983 are presented and discussed based on cytotaxonomic and karyoevolutionary inferences on Cichlasomatini. All individuals shared a diploid number of 2n=48 distributed as 10sm+28st+10a and Ag-NORs on short arms of a submetacentric pair. Heterochromatin was detected at pericentromeric regions of most chromosomes and at terminal sites of a few pairs. GC-rich regions were observed on short arms of two biarmed pairs, including the pair bearing Ag-NORs. Double-FISH with ribosomal probes revealed 18S rDNA clusters coincident with GC-rich regions in two biarmed pairs and 5S rDNA at interstitial location of an acrocentric pair. C. sanctifranciscense shares some symplesiomorphic traits described in Cichlidae (2n=48 and pericentromeric C-bands) while other chromosomal features diverge from the common trend reported in Cichlasomatini, such as multiple 18S rDNA sites combined with high FN values. Finally, the present results are useful to support taxonomic identification once species-specific markers have been provided in C. sanctifranciscense.

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Research Article Wed, 7 Oct 2015 10:18:19 +0300
Chromosomal distribution of microsatellite repeats in Amazon cichlids genome (Pisces, Cichlidae) https://compcytogen.pensoft.net/article/5582/ Comparative Cytogenetics 9(4): 595-605

DOI: 10.3897/CompCytogen.v9i4.5582

Authors: Carlos Henrique Schneider, Maria Claudia Gross, Maria Leandra Terencio, Edika Sabrina Girão Mitozo Tavares, Cesar Martins, Eiiana Feldberg

Abstract: Fish of the family Cichlidae are recognized as an excellent model for evolutionary studies because of their morphological and behavioral adaptations to a wide diversity of explored ecological niches. In addition, the family has a dynamic genome with variable structure, composition and karyotype organization. Microsatellites represent the most dynamic genomic component and a better understanding of their organization may help clarify the role of repetitive DNA elements in the mechanisms of chromosomal evolution. Thus, in this study, microsatellite sequences were mapped in the chromosomes of Cichla monoculus Agassiz, 1831, Pterophyllum scalare Schultze, 1823, and Symphysodon discus Heckel, 1840. Four microsatellites demonstrated positive results in the genome of C. monoculus and S. discus, and five demonstrated positive results in the genome of P. scalare. In most cases, the microsatellite was dispersed in the chromosome with conspicuous markings in the centromeric or telomeric regions, which suggests that sequences contribute to chromosome structure and may have played a role in the evolution of this fish family. The comparative genome mapping data presented here provide novel information on the structure and organization of the repetitive DNA region of the cichlid genome and contribute to a better understanding of this fish family’s genome.

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Research Article Mon, 14 Sep 2015 13:43:33 +0300
B chromosomes in the species Prochilodus argenteus (Characiformes, Prochilodontidae): morphologicalidentity and dispersion https://compcytogen.pensoft.net/article/4932/ Comparative Cytogenetics 9(1): 79-87

DOI: 10.3897/CompCytogen.v9i1.8587

Authors: Manolo Penitente, Fausto Foresti, Fabio Porto-Foresti

Abstract: B chromosomes have attracted the attention of Neotropical fish cytogeneticists in recent years, both for their remarkable occurrence in this group and also because of the interest in studies of the genetic structure and role played in the genome of these organisms. The aim of this study was to report the first occurrence of supernumerary chromosomes in Prochilodus argenteus (Agassiz, 1829), this being the fifth carrier species among thirteen within the genus Prochilodus (Agassiz, 1829). The extra elements identified in this species are small sized heterochromatic chromosomes characterized by a low mitotic instability index, being very similar to other supernumerary chromosomes described in the species of the genus Prochilodus. Morphology, structure and dispersion of the supernumerary genomic elements which occur in species of this genus are discussed aiming to better understand aspects involved the origin of supernumerary chromosomes and the differentiation process and relationships among species of this family.

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Short Communication Fri, 20 Mar 2015 00:00:00 +0200
Cytogenetic analysis of two locariid species (Teleostei, Siluriformes) from Iguatemi River (Parana River drainage) in Brazil https://compcytogen.pensoft.net/article/4847/ Comparative Cytogenetics 9(1): 67-78

DOI: 10.3897/CompCytogen.v9i1.8804

Authors: Carlos Alexandre Fernandes, Diandra Soares Alves, Zaira da Rosa Guterres, Isabel Cristina Martins-Santos

Abstract: Fishes of the Loricariidae family, known as “cascudos”, constitute an endemic group in Neotropical freshwaters. In this study, were cytogenetically examined two species of Loricariidae (Pterygoplichthys anisitsi Eigenmann & Kennedy, 1903 and Farlowella amazonum (Günther, 1864) belonging to Hypostominae and Loricariinae subfamilies respectively) from Iguatemi River. Our study provide the first description regarding C-band and fluorochromic analysis in F. amazonum. In Farlowella amazonum, diploid number was 58 chromosomes, with single Ag-NOR and heterochromatic blocks in centromeric regions of some chromosomes and large subtelomeric blocks were evidenced on the long arm of the pair 27, being this region CMA3+/DAPI-. The Pterygoplichthys anisitsi showed diploid number equal 52 chromosomes, with single Ag-NOR and heterochromatic blocks in centromeric and telomeric regions of some chromosomes and conspicuous large telomeric blocks on the long arm of the pair 10, being this region CMA3+/DAPI-. The results show that karyotype formula is nonconservative in P. anisitsi and F. amazonum.

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Research Article Tue, 10 Mar 2015 00:00:00 +0200
Basic cytogenetics and physical mapping of ribosomal genes in four Astyanax species (Characiformes, Characidae) collected in Middle Paraná River, Iguassu National Park: considerations on taxonomy and systematics of the genus https://compcytogen.pensoft.net/article/4703/ Comparative Cytogenetics 9(1): 51-65

DOI: 10.3897/CompCytogen.v9i1.9002

Authors: Leonardo Paiz, Lucas Baumgärtner, Weferson Júnio da Graça, Vladimir Margarido

Abstract: Karyotypes and chromosomal characteristics of both minor and major rDNAs in four fish species known popularly as “lambaris”, namely Astyanax abramis (Jenyns, 1842), Astyanax asuncionensis Géry, 1972, Astyanax correntinus (Holmberg, 1891) and Astyanax sp. collected from downstream of the Iguassu Falls (Middle Paraná River basin), preservation area of the Iguassu National Park, were analyzed by conventional and molecular protocols. A. abramis had diploid chromosome number 2n=50 (4m+30sm+8st+8a) and single AgNORs (pair 22), A. asuncionensis had 2n=50 (8m+24sm+6st+12a) and single AgNORs (pair 20), Astyanax sp. had 2n=50 (4m+26sm+8st+12a) and single AgNORs (pair 25), and A. correntinus had 2n=36 (12m+16sm+2st+6a) and multiple AgNORs (pairs 12, 15, 16, 17). FISH with 18S rDNA showed a single site for A. abramis, A. asuncionensis and Astyanax sp. and multiple for A. correntinus (14 sites). FISH with 5S rDNA showed single 5S-bearing loci chromosome pair only for A. asuncionensis and multiple for A. abramis (four sites), A. correntinus (five sites) and Astyanax sp. (four sites). Distinct distribution patterns of heterochromatin were observed for karyotypes of all species, with the exception of the first acrocentric chromosome pair characterized by centromeric, interstitial-proximal and telomeric blocks of heterochromatin on the long arm, which may represent homeology between karyotypes of A. abramis and A. asuncionensis. Our study showed species-specific characteristics which can serve in diagnosis and differentiation between A. abramis and A. asuncionensis, considered cryptic species, as well as strengthening the occurrence of a species of Astyanax not yet described taxonomically. In addition, the data obtained from first cytogenetic studies in A. correntinus suggest a high similarity with A. schubarti Britski, 1964, suggesting that these species may belong to the same morphological group and that can be phylogenetically related.

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Research Article Mon, 9 Feb 2015 00:00:00 +0200
Cytogenetic study of heptapterids (Teleostei, Siluriformes) with particular respect to the Nemuroglanis subclade https://compcytogen.pensoft.net/article/4685/ Comparative Cytogenetics 9(1): 17-29

DOI: 10.3897/CompCytogen.v9i1.8488

Authors: Daniel Kantek, Wellington Adriano Moreira Peres, Orlando Moreira-Filho

Abstract: The catfish family Heptapteridae (order Siluriformes) is endemic to the Neotropics and is one of the most common of the fish families in small bodies of water. Although over 200 species have been identified in this family, very few have been characterized cytogenetically. Here, we analyze the chromosome genomes of four species of Heptapteridae: Cetopsorhamdia iheringi (Schubart & Gomes, 1959), 2n = 58, comprising 28 metacentric (m) + 26 submetacentric (sm) + 4 subtelomeric (st) chromosomes; Pimelodella vittata (Lütken, 1874), 2n = 46, comprising 16m + 22sm + 8st; Rhamdia prope quelen (Quoy & Gaimard, 1824), 2n = 58 comprising 26m + 16sm + 14st + 2 acrocentric; and Rhamdiopsis prope microcephala (Lütken, 1874), 2n = 56, comprising 12m + 30sm + 14st. The nucleolus organizer regions (NORs) were located in a single chromosome pair in all species. The two species that belonged to the subclade Nemuroglanis, C. iheringi and R. prope quelen, had a diploid chromosome number of 58 and an interstitial NOR adjacent to a C+ block located on one of the larger chromosome pairs in the complement. Our results from conventional cytogenetic techniques in combination with FISH using 18S and 5S rDNA probes corroborated the taxonomical hypothesis for the formation of the Nemuroglanis subclade.

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Research Article Thu, 5 Feb 2015 00:00:00 +0200
Karyotype, C-banding and AgNORs of two endemic leuciscine fish, Pseudophoxinus crassus (Ladiges, 1960) and P. hittitorum Freyhof & Özulug, 2010 (Teleostei, Cyprinidae) https://compcytogen.pensoft.net/article/4205/ Comparative Cytogenetics 8(4): 249-257

DOI: 10.3897/CompCytogen.v8i4.7623

Authors: Sevgi Unal, Muhammet Gaffaroglu, Muradiye Karasu Ayata, Esref Yüksel

Abstract: The genus Pseudophoxinus Bleeker, 1860 is found in a wide range of habitats in central Anatolia, but it is not well known from a cytogenetic aspect. In this study the first karyotypic description of the spring minnows Pseudophoxinus crassus (Ladiges, 1960) and P. hittitorum Freyhof & Özulug, 2010 by means of conventional methods (Giemsa staining, C-banding, silver nitrate impregnation (Ag-NORs)) was performed. Both species are endemic and have restricted distributions in Central Anatolia. P. crassus and P. hittitorum have the same diploid chromosome number, 2n = 50, patterns of distribution of constitutive heterochromatin (CH), and localization of nucleolus organizer regions (NORs), but differ in their karyotypic formulae (KFs). The C-banding technique revealed clear pericentromeric blocks of CH in many chromosomes; Ag-NORs treatment revealed consistent positive signals at the end of the short arms of a submetacentric chromosome pair, likely homologous in both species. The karyotypic differences found between these species can be used for their taxonomical study.

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Research Article Fri, 31 Oct 2014 00:00:00 +0200
Molecular cytogenetic analysis of the crucian carp, Carassius carassius (Linnaeus, 1758) (Teleostei, Cyprinidae), using chromosome staining and fluorescence in situ hybridisation with rDNA probes https://compcytogen.pensoft.net/article/1815/ Comparative Cytogenetics 8(3): 233-248

DOI: 10.3897/compcytogen.v8i3.7718

Authors: Aneta Spoz, Alicja Boron, Katarzyna Porycka, Monika Karolewska, Daisuke Ito, Syuiti Abe, Lech Kirtiklis, Dorota Juchno

Abstract: The crucian carp Carassius carassius (Linnaeus, 1758) is a species with restricted and decreasing distribution in Europe. Six males and six females of the species from the Baltic Sea basin in Poland were examined to show sequentially CMA3/AgNO3 staining pattern, DAPI staining, and, for the first time in literature, molecular cytogenetic analysis using double-colour fluorescence in situ hybridisation (FISH) with 28S and 5S rDNA probes. The karyotype consisted of 20 m, 36 sm and 44 sta chromosomes, NF=156. The AgNO3 stained NORs were most frequently located terminally in the short arms of two sm and two sta elements, and CMA3-positive sites were also observed suggesting abundant GC-rich repetitive DNA in the regions. Other CMA3-positive sites in the short arms of six to ten sm and sta chromosomes were detected. The results based on 28S rDNA FISH confirmed the location of rDNA sites. DAPI-negative staining of NORs suggested the scarcity of AT-rich DNA in the regions. FISH with 5S rDNA probe revealed 8–14 loci (ten and 12 in respectively 49 and 29% of metaphases). They were located in two sm and eight to ten sta chromosomes and six of them were larger than others. Simultaneously, mapping of the two rDNA families on the chromosomes of C. carassius revealed that both 28S and 5S rDNA probes were located in different chromosomes. Molecular cytogenetic data of C. carassius presented here for the first time give an important insight into the structure of chromosomes of this polyploid and declining species and may be useful in its systematics.

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Research Article Mon, 18 Aug 2014 00:00:00 +0300
Basic cytogenetics and physical mapping of 5S and 18S ribosomal genes in Hoplias malabaricus (Osteichthyes, Characiformes, Erythrinidae) from isolated natural lagoons: a conserved karyomorph along the Iguaçu river basin https://compcytogen.pensoft.net/article/1817/ Comparative Cytogenetics 8(3): 211-222

DOI: 10.3897/compcytogen.v8i3.7084

Authors: Gisele Gemi, Roberto Lui, Fernando Treco, Leonardo Paiz, Rafaela Moresco, Vladimir Margarido

Abstract: Erythrinidae include Neotropical teleost fish that are widely distributed in South America. Hoplias Gill, 1903 include two large groups: H. malabaricus Bloch, 1794 and H. lacerdae Miranda Ribeiro, 1908. Hoplias malabaricus is characterized by remarkable karyotype diversity, with some karyomorphs widely distributed geographically while others are more restricted to certain river basins. Cytogenetic analyzes were performed in a population of Hoplias malabaricus from the Wildlife Refuge of Campos de Palmas, the Iguaçu River basin. The specimens showed diploid number of 42 chromosomes (24m+18sm) without differentiated sex chromosomes system. The impregnation by silver nitrate showed multiple AgNORs. Seven pairs (4, 7, 10, 13, 16, 20 and 21) carrying 18S rDNA were detected by FISH. Heterochromatin was verified in the centromeric and pericentromeric region of most chromosomes and the terminal region of some pairs. FISH with 5S rDNA probes showed two chromosome pairs carrying these sites in the interstitial region (8 and 14). The data obtained in this study are similar to those found for two other populations of H. malabaricus already studied in the basin of the Iguaçu River, confirming the hypothesis that this species is natural, notbeen introduced, as well asan intrinsic characteristic, such as the largest number of sites of 18S rDNA.

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Research Article Tue, 12 Aug 2014 00:00:00 +0300
Comparative cytogenetics of Neotropical cichlid fishes (Nannacara, Ivanacara and Cleithracara) indicates evolutionary reduction of diploid chromosome numbers https://compcytogen.pensoft.net/article/1820/ Comparative Cytogenetics 8(3): 169-183

DOI: 10.3897/compcytogen.v8i3.7279

Authors: Lucie Hodaňová, Lukáš Kalous, Zuzana Musilová

Abstract: A comparative cytogenetic analysis was carried out in five species of a monophyletic clade of neotropical Cichlasomatine cichlids, namely Cleithracara maronii Steindachner, 1881, Ivanacara adoketa (Kullander & Prada-Pedreros, 1993), Nannacara anomala Regan, 1905, N. aureocephalus Allgayer, 1983 and N. taenia Regan, 1912. Karyotypes and other chromosomal characteristics were revealed by CDD banding and mapped onto the phylogenetic hypothesis based on molecular analyses of four genes, namely cyt b, 16S rRNA, S7 and RAG1. The diploid numbers of chromosomes ranged from 44 to 50, karyotypes were composed predominantly of monoarmed chromosomes and one to three pairs of CMA3 signal were observed. The results showed evolutionary reduction in this monophyletic clade and the cytogenetic mechanisms (fissions/fusions) were hypothesized and discussed.

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Research Article Fri, 8 Aug 2014 00:00:00 +0300
Karyotypic similarities between two species of Rhamphichthys (Rhamphichthyidae, Gymnotiformes) from the Amazon basin https://compcytogen.pensoft.net/article/1801/ Comparative Cytogenetics 7(4): 279-291

DOI: 10.3897/compcytogen.v7i4.4366

Authors: Patrícia Silva, Cleusa Nagamachi, Danillo Silva, Susana Milhomem, Adauto Cardoso, Jonas Oliveira, Julio Pieczarka

Abstract: The family Rhamphichthyidae includes three genera: Rhamphichthys Müller et Troschel, 1846, Gymnorhamphichthys M. M. Ellis, 1912 and Iracema Triques, 1996. From this family, only the species Rhamphichthys hanni Meinken, 1937 has had its karyotype described. Here, we describe the karyotypes of two additional Rhamphichthys species: R. marmoratus Castelnau, 1855 from the Reserva de Desenvolvimento Sustentável Mamirauá, Amazonas state and R. prope rostratus Linnaeus, 1766 from Pará state, both in Brazil. Our karyotypic analyses demonstrated that the diploid number is conserved for the genus (2n = 50), but the karyotypic formulas (KFs) differed between R. marmoratus (44m/sm+6a) and R. prope rostratus (42m/sm+8a). In both species, the constitutive heterochromatin (CH) was located in the centromeric region of most chromosomes. Large heterochromatic blocks were found on the long arms of pairs 4 and 14 in R. marmoratus and on chromosomes 3, 4 and 19 in R. prope rostratus, which also has a heteromorphism in chromosome pair 1. The CH was DAPI positive, indicating that it is rich in AT base pairs. The Nucleolus Organizer Region (NOR) showed staining at a single location in both species: the long arm of pair 1 in R. marmoratus and the long arm of pair 12 in R. prope rostratus, where it showed a size heteromorphism. CMA3 staining coincided with that of Ag-NOR, indicating that the ribosomal genes contain interspaced GC-rich sequences. FISH with an 18S rDNA probe confirmed that there is only one NOR site in each species. These results can be used as potential cytogenetic markers for fish populations, and comparative analysis of the karyotypes of Hypopygus Hoedman, 1962, Rhamphichthys and Steatogenys Boulenger, 1898 suggests that the first two genera diverged later that the third.

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Research Article Thu, 24 Oct 2013 00:00:00 +0300
Karyotype and chromosome banding of endangered crucian carp, Carassius carassius (Linnaeus, 1758) (Teleostei, Cyprinidae) https://compcytogen.pensoft.net/article/1797/ Comparative Cytogenetics 7(3): 205-213

DOI: 10.3897/compcytogen.v7i3.5411

Authors: Martin Knytl, Lukáš Kalous, Petr Rab

Abstract: The karyotype and other chromosomal characteristics the crucian carp (Carassius carassius (Linnaeus, 1758)) were revealed by means of conventional banding protocols (C, CMA3, AgNOR). The diploid chromosome number (2n) in this species was 100. Its karyotype was composed of 10 pairs of metacentric, 18 pairs of submetacentric and 22 pairs of subtelo- to acrocentric chromosomes without any microchromosomes. C-banding identified blocks of telomeric heterochromatin on seven chromosome pairs. The NORs were situated on the p arms of the 14th pair of submetacentric chromosomes and on the p arms of the 32nd pair of subtelo-acrocentric chromosomes; AgNOR-positive signals corresponded to the CMA3-positive signals. These chromosome characteristics may suggest a paleo-allotetraploid origin of C. carassius genome.

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Research Article Fri, 23 Aug 2013 00:00:00 +0300
New method for visualization of C-heterochromatin in synaptonemal complex spreads https://compcytogen.pensoft.net/article/1791/ Comparative Cytogenetics 7(2): 131-138

DOI: 10.3897/compcytogen.v7i2.5187

Authors: Artem Lisachov

Abstract: DAPI staining of the metaphase chromosomes pretreated with barium hydroxide generates a C-like banding pattern. In this work a protocol for visualizing similar pattern at the synaptonemal complex (SC) spreads after immunostaining is suggested. This method was used to visualize centromeric and sex heterochromatin at the SC spreads of guppy fish (Poecilia reticulata Peters, 1859). The efficiency of this method was further confirmed at SC spreads of the northern red-backed vole (Myodes rutilus (Pallas, 1779)), the guinea pig (Cavia porcellus (Linnaeus, 1758)), and the pigmy shrew (Sorex minutus Linnaeus, 1766).

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Research Article Wed, 22 May 2013 00:00:00 +0300
Comparative chromosomal analysis and evolutionary considerations concerning two species of genus Tatia (Siluriformes, Auchenipteridae) https://compcytogen.pensoft.net/article/1780/ Comparative Cytogenetics 7(1): 63-71

DOI: 10.3897/compcytogen.v7i1.4368

Authors: Roberto Lui, Daniel Blanco, Vladimir Margarido, Waldo Troy, Orlando Moreira Filho

Abstract: Auchenipteridae is divided in two subfamilies, Centromochlinae and Auchenipterinae. Centromochlinae has 31 valid species, from which 13 are included in the genus Tatia Miranda Ribeiro, 1911. Among these, Tatia jaracatia Pavanelli & Bifi, 2009 and T. neivai (Ihering, 1930) are the only two representative species from the Paraná-Paraguay basins. This study aimed to analyze cytogenetically these two species and thus provide the first chromosomal data for the genus. Although T. jaracatia and T. neivai presented 2n=58 chromosomes, some differences were observed in the karyotypic formula. The heterochromatin was dispersed in the centromeric and terminal regions of most chromosomes of T. jaracatia, and only in the terminal region of most chromosomes of T. neivai. The AgNORs were detected in the subtelocentric pair 28 for both species, which was confirmed by FISH with 18S rDNA probe. The 5S rDNA sites were detected in four chromosome pairs in T. jaracatia and three chromosome pairs in T. neivai. Both species of Tatia presented great chromosomal similarities among themselves; however, when compared to other species of Auchenipteridae, it was possible to identify some differences in the karyotype macrostructure, in the heterochromatin distribution pattern and in the number and position of 5S rDNA sites, which until now seems to be intrinsic to the genus Tatia.

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Research Article Wed, 10 Apr 2013 00:00:00 +0300
Cytogenetic analysis in Thoracocharax stellatus (Kner, 1858) (Characiformes, Gasteropelecidae) from Paraguay River Basin, Mato Grosso, Brazil https://compcytogen.pensoft.net/article/1758/ Comparative Cytogenetics 6(3): 323-333

DOI: 10.3897/compcytogen.v6i3.3637

Authors: Edson Silva, Rafael de Borba, Liano Centofante, Carlos Miyazawa, Patricia Parise-Maltempi

Abstract: Thoracocharax stellatus (Characiformes, Gasteropelecidae) is a small Neotropical species of fish, widely distributed in several rivers of South America. Evidence for karyotype heteromorphysm in populations from different geographical regions has been reported for this species. In this way, populations of T. stellatus from the Paraguay River basin were cytogenetically characterized and the results were compared with other studies performed in the same species but from different basins. The results showed a diploid number of 2n = 54 for T. stellatus, with chromosomes arranged in 6 metacentric (m), 6 submetacentric (sm), 2 subtelocentric (st) and 40 acrocentric (a), for both sexes, with a simple Nucleolus Organiser Region (NOR) system reported by the techniques of silver nitrate impregnation and fluorescent in situ hybridisation (FISH) using 18S rDNA sequences as probe. The distribution of constitutive heterochromatin, observed by the C-band technique and Chromomycin A3 staining showed great similarity among the analyzed populations and consists mainly of discrete blocks in the pericentromeric and telomeric regions of most chromosomes. The presence of female heterogamety was also observed indicating a ZZ/ZW system with W chromosome almost totally heterochromatic. The results also show cytogenetic diversity of the group and are useful to understand the mechanisms of karyotype evolution of the family.

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Research Article Wed, 26 Sep 2012 00:00:00 +0300
Identifying parental chromosomes and genomic rearrangements in animal hybrid complexes of species with small genome size using Genomic In Situ Hybridization (GISH) https://compcytogen.pensoft.net/article/1761/ Comparative Cytogenetics 6(3): 287-300

DOI: 10.3897/compcytogen.v6i3.3543

Authors: Massimiliano Rampin, Ke Bi, James Bogart, Maria Joao Collares Pereira

Abstract: Genomic In Situ Hybridization (GISH), a powerful tool to identify and to quantify genomic constituents in allopolyploids, has been widely used in plants but not in animals mainly due to technical problems in obtaining informative results. Using the allopolyploid Squalius alburnoides fish complex as a model system, we succeeded in overcoming methodological constraints when dealing with parental species with a small genome size. This hybridogenetic complex has biotypes with different genome compositions and ploidy levels, but parental chromosomes are small, morphologically very similar and therefore cannot be distinguished by conventional cytogenetic approaches. Specimens have a small genome (C-value = 1.2 pg) with a low level of highly and moderate repetitive sequences, mainly located at pericentromeric chromosome regions. Since it is well known that probe annealing depends on probe concentration and hybridization time to obtain uniform hybridization signals along the chromosome arms, we progressively increased the amount of labeled probes from 100ng up to 1µg per slide and the incubation time from overnight up to 72 h, among other minor improvements. Results showed a clear enhancement of signals with respect to previous data, allowing an accurate and reproducible assignment of the parental genomes in both diploid and triploid fish. It was thus evidenced that high probes’ concentrations and long incubation time are the key to obtain, without extra image editing, uniform and reliable hybridization signals in metaphase chromosomes of hybrid fish even involving parental species with small genome size.

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Research Article Fri, 14 Sep 2012 00:00:00 +0300
Comparative cytogenetics of ten species of cichlid fishes (Teleostei, Cichlidae) from the Araguaia River system, Brazil, by conventional cytogenetic methods https://compcytogen.pensoft.net/article/1752/ Comparative Cytogenetics 6(2): 163-181

DOI: 10.3897/compcytogen.v6i2.1739

Authors: Guilherme Valente, Carla Vitorino, Diogo Cabral-de-Mello, Claudio Oliveira, Issakar Souza, Cesar Martins, Paulo Venere

Abstract: Cichlids represent one of the most species-rich families of fishes and have attracted the attention of evolutionary biologists due to the rapid radiation occurring in some groups and the importance of some species in the world aquaculture. Cytogenetic analysis was conducted in 10 cichlid species from the Araguaia River, Amazon Basin, Brazil. The chromosome number was 2n=48 for all analyzed species except for Laetacara araguaiae Ottoni et Costa, 2009 (2n=44). Chromosomal polymorphism was detected only in Geophagus proximus (Castelnau, 1855), which exhibits an extra large submetacentric and and a dot-like chromosomes. Moreover, the C-banding revealed a general pericentromeric heterochromatic pattern and some additional blocks for some species. The heterochromatic blocks corresponding to AgNOR bearing regions were observed in all species and also corresponded to CMA3 positive blocks, which were observed in terminal regions. Besides the general conserved chromosomal and heterochromatin patterns for South American cichlids, the presence of GC-rich heterochromatin was quite different in the species Biotodoma cupido (Heckel, 1840), Geophagus proximus, Retroculus lapidifer (Castelnau, 1855), Crenicichla strigata Günther, 1862 and Heros efasciatus Heckel, 1840. The results suggest that independent events of heterochromatin modification occurred during chromosome evolution in the group, regardless of the conservation of macro-chromosomal structure.

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Research Article Fri, 27 Apr 2012 00:00:00 +0300
Cytogenetic analysis of B chromosomes in one population of the fish Moenkhausia sanctaefilomenae (Steindachner, 1907) (Teleostei, Characiformes) https://compcytogen.pensoft.net/article/1754/ Comparative Cytogenetics 6(2): 141-151

DOI: 10.3897/compcytogen.v6i2.1769

Authors: Diogo Hashimoto, Tatiana Voltolin, Ana Paes, Fausto Foresti, Jehud Bortolozzi, Fabio Porto-Foresti

Abstract: The aim of this study was to characterize cytogenetically one population of the fish Moenkhausia sanctaefilomenae (Steindachner, 1907), with emphasis on the analysis of B chromosomes. The nucleolar activity in the B microchromosomes was characterized, and an analysis of mitotic instability of these microchromosomes was accomplished. The results showed a diploid chromosome number of 50 chromosomes. In all individuals, we observed the presence of B microchromosomes with intra- and inter-individual variability. The analysis of the nucleolus organizing regions (NORs) by silver nitrate staining demonstrated multiple NORs. We observed active sites of ribosomal DNA in the B microchromosomes, with a frequency of 20% in the analyzed cells, which shows gene activity in these chromosomal elements. The analysis of constitutive heterochromatin patterns showed that the B microchromosomes are heterochromatic or euchromatic, which demonstrates differentiation of DNA composition between these genomic elements. The calculation of the mitotic instability index implied that B chromosomes in this species might be in a final stage of instability.

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Research Article Mon, 9 Apr 2012 00:00:00 +0300
First karyotype description of Hypostomus iheringii (Regan, 1908): a case of heterochromatic polymorphism https://compcytogen.pensoft.net/article/1756/ Comparative Cytogenetics 6(2): 115-125

DOI: 10.3897/compcytogen.v6i2.2595

Authors: Josiane Traldi, Marcelo Vicari, Daniel Blanco, Juliana Martinez, Roberto Artoni, Orlando Moreira Filho

Abstract: In this study, which is the first karyotype analysis of Hypostomus iheringii, nine specimens collected in Córrego da Lapa (tributary of the Passa-Cinco River) showed a diploid number of 80 chromosomes. Silver nitrate staining and fluorescence in situ hybridization (FISH) with an 18S rDNA probe revealed the presence of multiple nucleolus organizer regions (NORs) (chromosome pairs 13, 20, and 34). FISH with a 5S rDNA probe showed that this cistron was only present in chromosome pair 2. When the karyotypes of individual animals were compared, unique heterochromatic polymorphisms were detected on chromosome pairs 1 and 5. Specifically, specimens had heterochromatic blocks (h+h+) on both chromosomes, one chromosome with heterochromatic blocks (h+h-) or chromosomes that lacked heterochromatic blocks (h-h-). Considering that heteromorphic pattern is not correlated with variation in size, the process of heterochromatinization might act on the long arms of these chromosomes. In summary, all chromosomal markers indicate that the karyotype of H. iheringii is highly differentiated and that the heterochromatinization of chromosomal segments may have contributed to its karyotypic differentiation.

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Research Article Fri, 16 Mar 2012 00:00:00 +0200
Heterochromatin heterogeneity in Hypostomus prope unae (Steindachner, 1878) (Siluriformes, Loricariidae) from Northeastern Brazil https://compcytogen.pensoft.net/article/1730/ Comparative Cytogenetics 5(4): 329-344

DOI: 10.3897/compcytogen.v5i4.1149

Authors: Jamille Bitencourt, Paulo Roberto Affonso, L. Giuliano-Caetano, A. L. Dias

Abstract: Cytogenetic analyses using C-banding and chromosomal digestion by several restriction enzymes were carried out in four populations (named A, B, C and D) of Hypostomus prope unae (Loricariidae, Hypostominae) from Contas river basin, northeastern Brazil. These populations share 2n=76 and single NORs on the second metacentric pair but exclusive karyotype forms for each locality. Populations A and B presented conspicuous terminal and interstitial heterochromatic blocks on most of acrocentric chromosomes and equivalent to NORs with differences in both position and bearing pair. Population D showed evident marks at interstitial regions and interspersed with nucleolar region while population C presented interstitial and terminal heterochromatin segments, non-coincident with NORs. The banding pattern after digestion with the endonucleases Alu I, Bam HI, Hae III and Dde I revealed a remarkable heterogeneity within heterochromatin, allowing the identification of distinctive clusters of repeated DNA in the studied populations, besides specific patterns along euchromatic regions. The analysis using restriction enzymes has proved to be highly informative, characterizing population differences and peculiarities in the genome organization of H. prope unae.

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Research Article Wed, 9 Nov 2011 00:00:00 +0200
Chromosomal complements of some Atlantic Blennioidei and Gobioidei species (Perciformes) https://compcytogen.pensoft.net/article/1735/ Comparative Cytogenetics 5(4): 259-275

DOI: 10.3897/compcytogen.v5i4.1834

Authors: Tatiana Galvão, Luiz Bertollo, Wagner Molina

Abstract: A remarkable degree of chromosomal conservatism (2n=48, FN=48) has been identified in several families of Perciformes. However, some families exhibit greater karyotypic diversity, although there is still scant information on the Atlantic species. In addition to a review of karyotypic data available for representatives of the suborders Blennioidei and Gobioidei, we have performed chromosomal analyses on Atlantic species of the families Blenniidae, Ophioblennius trinitatis Miranda-Ribeiro, 1919 (2n=46; FN=64) and Scartella cristata (Linnaeus, 1758) (2n=48; FN=50), Labrisomidae, Labrisomus nuchipinnis (Quoy & Gaimard, 1824) (2n=48; FN=50) and Gobiidae, Bathygobius soporator (Valenciennes, 1837) (2n=48; FN=56). Besides variations in chromosome number and karyotype formulas, Ag-NOR sites, albeit unique, were located in different positions and/or chromosome pairs for the species analyzed. On the other hand, the heterochromatic pattern was more conservative, distributed predominantly in the centromeric/pericentromeric regions of the four species. Data already available for Gobiidae, Blenniidae and Labrisomidae show greater intra- and interspecific karyotypic diversification when compared to other groups of Perciformes, where higher uniformity is found for various chromosome characteristics. Evolutionary dynamism displayed by these two families is likely associated with population fractionation resulting from unique biological characteristics, such as lower mobility and/or specific environmental requirements.

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Research Article Wed, 9 Nov 2011 00:00:00 +0200
Cytogenetic characterization of three Balistoidea fish species from the Atlantic with inferences on chromosomal evolution in the families Monacanthidae and Balistidae https://compcytogen.pensoft.net/article/1713/ Comparative Cytogenetics 5(1): 61-69

DOI: 10.3897/compcytogen.v5i1.1141

Authors: Lorena Lima, Pablo Martinez, Wagner Molina

Abstract: The Tetraodontiformes are the most derived group of teleostean fish. Among other apomorphies, they are characterized by a high degree of fusions or significant bone loss in the head and body. In the early phylogenetic proposals presented for this order, the families Balistidae and Monacanthidae have been unanimously considered to be closely related. Although they have moderate species diversity, they are scarcely known in cytogenetic aspect and chromosomal pattern comparisons between these groups have yet to be established. The species Cantherhines macrocerus (Hollard,1853), C. pullus (Ranzani, 1842) (Monacanthidae) and Melichthys niger (Bloch, 1786) (Balistidae) were cytogenetically analyzed using conventional (Ag-impregnation, C-banding, CMA3- and DAPI-fluorescence) and molecular (FISH with an 18S rDNA probe) cytogenetic protocols. The karyotypes of all three species were very similar possessing diploid chromosome numbers 2n = 40 and composed exclusively of acrocentric chromosomes. Single NOR-bearing pair as well as positive heterochromatic blocks at pericentromeric regions were identified in the karyotypes of the three species studied. NOR-bearing sites were positively labeled after Ag-impregnation, C-banding, CMA3-fluorescence and FISH with an 18S rDNA probe but were negative after DAPI-fluorescence. Such remarkable shared conspicuous chromosomal characters corroborate either close phylogenetic relationship of these families, previously established by morphological and molecular data, or rather conservative nature of karyotype differentiation processes. The later hypothesis, however, appears less probable due to centric or in tandem fusions documented for another Balistoidea species.

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Research Article Thu, 5 May 2011 00:00:00 +0300
Cytogenetic characterization of Brycon amazonicus (Spix et Agassiz, 1829) (Teleostei: Characidae) from Caicara del Orinoco, Venezuela https://compcytogen.pensoft.net/article/1706/ Comparative Cytogenetics 4(2): 185-193

DOI: 10.3897/compcytogen.v4i2.49

Authors: T Mariguela, M Nirchio, E Ron, J Gaviria, Fausto Foresti, Claudio Oliveira

Abstract: A cytogenetic analysis by conventional Giemsa staining, silver staining, C-banding, and fluorescence in situ hybridization (FISH) was carried out on Brycon amazonicus from Caicara del Orinoco, Venezuela. The karyotype of this species is characterized by the presence of 2n = 50 chromosomes, a karyotypic formula 22m+14sm+14st, and a fundamental number of 100 chromosomal arms. Nucleolar organizer regions (NORs) and 18S rDNA genes are located in the terminal regions of the long arms of the second pair of subtelocentric chromosomes, corresponding to pair 13. C-banding revealed heterochromatin distribution in only seven chromosome pairs. The largest metacentric pair (number 1) possesses a paracentromeric block equilocally distributed in both chromosome arms, whereas in pairs 12 to 17 positive C band blocks were located in the paracentromeric region of the long arm, close to the centromere. Analysis performed with 5S rDNA gene revealed a terminal site located on the short arm of one small submetacentric chromosome (pair 15) corroborating previous studies with this repetitive gene showing an apparent conservation of 5S rDNA in the genome of these fish species. The data obtained in this study reinforce the chromosomal conservativeness in the species of the genus Brycon, related not only to the macro-chromosomal structure (diploid number, karyotypic formula, and fundamental number), but also to the repeated DNAs, such as heterochromatic regions and ribosomal DNAs. These data will contribute to a better understanding of chromosomal evolution in both Brycon and Characidae fishes.

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Research Article Thu, 30 Dec 2010 00:00:00 +0200
Differential chromosomal markers between sympatric karyomorphs of the fish Hoplias malabaricus (Bloch, 1794) (Characiformes: Erythrinidae) https://compcytogen.pensoft.net/article/1705/ Comparative Cytogenetics 4(2): 175-184

DOI: 10.3897/compcytogen.v4i2.48

Authors: Renata Rosa, Marceléia Rubert, L. Giuliano-Caetano, I Martins-Santos

Abstract: Cytogenetic analyses were performed on Hoplias malabaricus (Bloch, 1794) from the Taquari River, Parana River drainage, revealing two sympatric karyomorphs. One karyomorph was characterized by 2n = 40 m/sm and 2n = 39 m/sm chromosomes for females and males, respectively, and an X1X1X2X2/X1X2Y sex chromosome system. In the second karyomorph, specimens showed 2n = 42 m/sm chromosomes, without sex-related heteromorphism. Both karyomorphs were characterized by a distribution of heterochromatin in the pericentromeric and telomeric regions. In addition to the differences in the diploid numbers and the sex chromosomes, the GC-rich sites and the nucleolar organizer regions also showed clear differences between the karyomorphs. Coupled with the occurrence of unique chromosomal features within each karyomorph, the fact that hybrids have not been identified in the sampled population provides additional support of the existence of a species complex in H. malabaricus.

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Research Article Thu, 30 Dec 2010 00:00:00 +0200