Latest Articles from Comparative Cytogenetics Latest 69 Articles from Comparative Cytogenetics https://compcytogen.pensoft.net/ Fri, 29 Mar 2024 12:57:35 +0200 Pensoft FeedCreator https://compcytogen.pensoft.net/i/logo.jpg Latest Articles from Comparative Cytogenetics https://compcytogen.pensoft.net/ First karyotype description of the species of Adenomera Steindachner, 1867 (Anura, Leptodactylidae) in the “ thomei” clade https://compcytogen.pensoft.net/article/82641/ Comparative Cytogenetics 16(3): 151-159

DOI: 10.3897/compcytogen.v16.i3.82641

Authors: Ramon Costa Dominato, Guilherme Costa de Oliveira, Carla Santana Cassini, Victor Goyannes Dill Orrico, Cléa dos Santos Ferreira Mariano, Janisete Gomes Silva

Abstract: The genus Adenomera Steindachner, 1867 currently comprises 29 nominal species, some of which are suggested to be cryptic species complexes. The present study was carried out with specimens of the “thomei” clade that encompasses three taxa distributed in the Atlantic Forest biome: Adenomera thomei Almeida et Angulo, 2006, Adenomera sp. L., and Adenomera sp. M. We used classical cytogenetics to describe the diploid number and karyomorphology of these three species collected in two different locations in the state of Bahia, Brazil. Our results revealed the diploid number 2n = 24 (FN = 34) with two pairs of metacentric chromosomes (pairs 1 and 5), three pairs of submetacentric chromosomes (pairs 2, 3, and 4), and seven pairs of telocentric chromosomes (pairs 6, 7, 8, 9, 10, 11, and 12). Further morphological, bioacoustic, and cytogenetic data (C-banding and AgNor) are needed to better delineate the lineages within the “thomei” clade.

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Short Communication Tue, 30 Aug 2022 12:58:41 +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
Distribution of GC-rich heterochromatin and ribosomal genes in three fungus-farming ants (Myrmicinae, Attini, Attina): insights on chromosomal evolution https://compcytogen.pensoft.net/article/73769/ Comparative Cytogenetics 15(4): 413-428

DOI: 10.3897/compcytogen.v15.i4.73769

Authors: Gisele Amaro Teixeira, Luísa Antônia Campos Barros, Hilton Jeferson Alves Cardoso de Aguiar, Denilce Meneses Lopes

Abstract: Cytogenetic studies on fungus-farming ants have shown remarkable karyotype diversity, suggesting different chromosomal rearrangements involved in karyotype evolution in some genera. A notable cytogenetic characteristic in this ant group is the presence of GC-rich heterochromatin in the karyotypes of some ancient and derivative species. It was hypothesized that this GC-rich heterochromatin may have a common origin in fungus-farming ants, and the increase in species studied is important for understanding this question. In addition, many genera within the subtribe Attina have few or no cytogenetically studied species; therefore, the processes that shaped their chromosomal evolution remain obscure. Thus, in this study, we karyotyped, through classical and molecular cytogenetic techniques, the fungus-farming ants Cyphomyrmex transversus Emery, 1894, Sericomyrmex maravalhas Ješovnik et Schultz, 2017, and Mycetomoellerius relictus (Borgmeier, 1934), to provide insights into the chromosomal evolution in these genera and to investigate the presence the GC-rich heterochromatin in these species. Cyphomyrmex transversus (2n = 18, 10m + 2sm + 6a) and S. maravalhas (2n = 48, 28m + 20sm) showed karyotypes distinct from other species from their genera. Mycetomoellerius relictus (2n = 20, 20m) presented the same karyotype as the colonies previously studied. Notably, C. transversus presented the lowest chromosomal number for the genus and a distinct karyotype from the other two previously observed for this species, showing the existence of a possible species complex and the need for its taxonomic revision. Chromosomal banding data revealed GC-rich heterochromatin in all three species, which increased the number of genera with this characteristic, supporting the hypothesis of a common origin of GC-rich heterochromatin in Attina. Although a single chromosomal pair carries rDNA genes in all studied species, the positions of these rDNA clusters varied. The rDNA genes were located in the intrachromosomal region in C. transversus and M. relictus, and in the terminal region of S. maravalhas. The combination of our molecular cytogenetic data and observations from previous studies corroborates that a single rDNA site located in the intrachromosomal region is a plesiomorphic condition in Attina. In addition, cytogenetic data obtained suggest centric fission events in Sericomyrmex Mayr, 1865, and the occurrence of inversions as the origin of the location of the ribosomal genes in M. relictus and S. maravalhas. This study provides new insights into the chromosomal evolution of fungus-farming ants.

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Research Article Thu, 25 Nov 2021 03:07:11 +0200
Comparative cytogenetics of two species of Dermanura (Chiroptera, Phyllostomidae) in Midwestern Brazil https://compcytogen.pensoft.net/article/60577/ Comparative Cytogenetics 15(2): 89-99

DOI: 10.3897/CompCytogen.v15.i2.60577

Authors: Ricardo Firmino de Sousa, Paulo Cesar Venere, Karina de Cassia Faria

Abstract: Dermanura Gervais, 1856 is represented by small frugivorous bats of the Stenodermatinae subfamily. The taxonomy of this group presents controversies and has been subject to changes, especially since the morphological characters evaluated have left gaps that are difficult to fill regarding good species characterization. Previous studies performed in Dermanura cinerea Gervais, 1856 found that the karyotype of this species has a diploid number of chromosomes equal to 30 and 56 autosomal arms. The objective of the present study was to describe, for the first time, the karyotypes of the species Dermanura anderseni (Osgood, 1916) and Dermanura gnoma (Handley, 1987) based on classical cytogenetic markers. For both species, the diploid number found was 2n = 30 and NFa = 56. Two pairs of chromosomes showed markings of the nucleolus organizing regions (AgNORs) in the species D. anderseni and only one pair in D. gnoma, differing from what has already been described for D. cinerea. The two species analyzed here also showed differences in the sex chromosome system, with D. gnoma showing a neo-XY type system while in D. anderseni the classic XY sexual system was observed. In both species, visualization of the constitutive heterochromatin occurred in the pericentromeric region of all chromosomes, as well as in the short arms of the subtelocentric chromosomes. The present work represents an important expansion of karyotypic information for the subfamily Stenodermatinae, bringing chromosomal features that are possible to use in the taxonomic implications of the group.

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Research Article Fri, 2 Apr 2021 12:07:15 +0300
Chromosomal mapping of repetitive DNA in Melipona seminigra merrillae Cockerell, 1919 (Hymenoptera, Apidae, Meliponini) https://compcytogen.pensoft.net/article/56430/ Comparative Cytogenetics 15(1): 77-87

DOI: 10.3897/CompCytogen.v15.i1.56430

Authors: Ingrid Cândido de Oliveira Barbosa, Carlos Henrique Schneider, Leonardo Gusso Goll, Eliana Feldberg, Gislene Almeida Carvalho-Zilse

Abstract: Melipona Illiger, 1806 is represented by 74 known species of stingless bees, distributed throughout the Neotropical region. Cytogenetically it is the most studied stingless bee genus of the tribe Meliponini. Member species are divided in two groups based on the volume of heterochromatin. This study aim was to analyze the composition and organization of chromatin of the stingless bee subspecies Melipona seminigra merrillae Cockerell, 1919 using classical and molecular cytogenetic techniques, so contributing to a better understanding of the processes of chromosomal changes within the genus. We confirm that M. seminigra merrillae has a chromosome number of 2n = 22 and n = 11, results that differ from those reported for the genus in the absence of B chromosomes. The heterochromatic pattern revealed a karyotype composed of chromosomes with a high heterochromatin content, which makes it difficult to visualize the centromere. Silver nitrate impregnation (Ag-NOR) showed transcriptionally active sites on the second chromosomal pair. Staining of base-specific fluorophores DAPI-CMA3 indicated a homogeneous distribution of intensely DAPI-stained heterochromatin, while CMA3 markings appeared on those terminal portions of the chromosomes corresponding to euchromatin. Similar to Ag-NOR, fluorescence in situ hybridization (FISH) with 18S ribosomal DNA probe revealed distinct signals on the second pair of chromosomes. Microsatellite mapping (GA)15 showed markings distributed in euchromatic regions, while mapping with (CA)15 showed marking patterns in heterochromatic regions, together with a fully marked chromosome pair. Microsatellite hybridization, both in heterochromatic and euchromatic regions, may be related to the activity of transposable elements. These are capable of forming new microsatellites that can be dispersed and amplified in different regions of the genome, demonstrating that repetitive sequences can evolve rapidly, thus resulting in within-genus diversification.

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Research Article Fri, 19 Mar 2021 20:33:49 +0200
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
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
Cytogenetic data for sixteen ant species from North-eastern Amazonia with phylogenetic insights into three subfamilies https://compcytogen.pensoft.net/article/46692/ Comparative Cytogenetics 14(1): 43-60

DOI: 10.3897/CompCytogen.v14i1.46692

Authors: Hilton Jeferson Alves Cardoso de Aguiar, Luísa Antônia Campos Barros, Linda Inês Silveira, Frédéric Petitclerc, Sandrine Etienne, Jérôme Orivel

Abstract: Ants play essential roles in most terrestrial ecosystems and may be considered pests for agriculture and agroforestry. Recent morphological and molecular data have challenged conventional ant phylogeny and the interpretation of karyotypic variations. Existing Neotropical ant cytogenetic data focus on Atlantic rainforest species, and provide evolutionary and taxonomic insight. However, there are data for only 18 Amazonian species. In this study, we describe the karyotypes of 16 ant species belonging to 12 genera and three subfamilies, collected in the Brazilian state of Amapá, and in French Guiana. The karyotypes of six species are described for the first time, including that of the South American genus Allomerus Mayr, 1878. The karyotype of Crematogaster Lund, 1831 is also described for the first time for the New World. For other species, extant data for geographically distinct populations was compared with our own data, e.g. for the leafcutter ants Acromyrmex balzani (Emery, 1890) and Atta sexdens (Linnaeus, 1758). The information obtained for the karyotype of Dolichoderus imitator Emery, 1894 differs from extant data from the Atlantic forest, thereby highlighting the importance of population cytogenetic approaches. This study also emphasizes the need for good chromosome preparations for studying karyotype structure.

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Research Article Wed, 22 Jan 2020 12:21:07 +0200
Chromosome spreading of the (TTAGGG)n repeats in the Pipa carvalhoi Miranda-Ribeiro, 1937 (Pipidae, Anura) karyotype https://compcytogen.pensoft.net/article/35524/ Comparative Cytogenetics 13(3): 297-309

DOI: 10.3897/CompCytogen.v13i3.35524

Authors: Michelle Louise Zattera, Luana Lima, Iraine Duarte, Deborah Yasmin de Sousa, Olívia Gabriela dos Santos Araújo, Thiago Gazoni, Tamí Mott, Shirlei Maria Recco-Pimentel, Daniel Pacheco Bruschi

Abstract: Pipidae is a clade of Anura that diverged relatively early from other frogs in the phylogeny of the group. Pipids have a unique combination of morphological features, some of which appear to represent a mix of adaptations to aquatic life and plesiomorphic characters of Anura. The present study describes the karyotype of Pipa carvalhoi Miranda-Ribeiro, 1937, including morphology, heterochromatin distribution, and location of the NOR site. The diploid number of P. carvalhoi is 2n=20, including three metacentric pairs (1, 4, 8), two submetacentric (2 and 7), three subtelocentric (3, 5, 6), and two telocentric pairs (9 and 10). C-banding detected centromeric blocks of heterochromatin in all chromosome pairs and the NOR detected in chromosome pair 9, as confirmed by FISH using the rDNA 28S probe. The telomeric probes indicated the presence of interstitial telomeric sequences (ITSs), primarily in the centromeric region of the chromosomes, frequently associated with heterochromatin, suggesting that these repeats are a significant component of this region. The findings of the present study provide important insights for the understanding of the mechanisms of chromosomal evolution in the genus Pipa, and the diversification of the Pipidae as a whole.

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Research Article Mon, 14 Oct 2019 17:57:14 +0300
Karyotypes of three species of Hyperophora Brunner von Wattenwyl, 1878 (Tettigoniidae, Phaneropterinae) enable morphologically similar species to be distinguished https://compcytogen.pensoft.net/article/31803/ Comparative Cytogenetics 13(1): 87-93

DOI: 10.3897/CompCytogen.v13i1.31803

Authors: Bruno Cansanção Silva, Lucas Henrique Bonfim Souza, Juliana Chamorro-Rengifo, Douglas Araujo

Abstract: Phaneropterinae is the largest subfamily of Tettigoniidae, distributed across the globe. There are few cytogenetic studies regarding this group, as in the case of the genus group Aniarae, which represents only two karyotyped species. The current study aims to analyze cytogenetically three species of Hyperophora Brunner von Wattenwyl, 1878 from Brazil. The male diploid number of Hyperophora minor Brunner von Wattenwyl, 1891 and Hyperophora major Brunner von Wattenwyl, 1878 is 2n♂= 31, whereas Hyperophora brasiliensis Brunner von Wattenwyl, 1878 has shown 2n♂= 29. These three species possess an X0 sex chromosome system and telo/acrocentric chromosome morphology. The only species found in the Pantanal biome, H. brasiliensis, can be chromosomally distinguished from the Cerrado biome species H. major and H. minor, due to the difference in chromosome number (2n♂= 29 and 2n♂= 31, respectively).

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Research Article Tue, 2 Apr 2019 11:38:02 +0300
Karyotypic description of the stingless bee Melipona quinquefasciata Lepeletier, 1836 (Hymenoptera, Meliponini) with emphasis on the presence of B chromosomes https://compcytogen.pensoft.net/article/29165/ Comparative Cytogenetics 12(4): 471-482

DOI: 10.3897/CompCytogen.v12i4.29165

Authors: Alexandra Avelar Silva, Marla Piumbini Rocha, Silvia das Graças Pompolo, Lucio Antonio de Oliveira Campos, Mara Garcia Tavares

Abstract: Stingless bees are distributed widely in the tropics, where they are major pollinators of several plant species. In this study, the karyotype of Melipona quinquefasciata Lepeletier, 1836 was analysed, with emphasis on the presence of B chromosomes. Post-defecating larvae were analysed using Giemsa staining, the C-banding technique, sequential staining with fluorochromes, and FISH. The chromosome number ranged from 2n = 18 to 22 (females) and from n = 9 to 13 (males) due to the presence of 0–4 B chromosomes. This result demonstrates that M. quinquefasciata has the same chromosomal number as other Melipona Illiger, 1806 species. Considering the A complement, heterochromatin was located only in the pericentromeric region of pair 1. Staining with chromomycin A3 (CMA3) and labelling with rDNA probe, indicated that this region corresponded to the nucleolus organising region. The B chromosomes of M. quinquefasciata could be found in individuals from different localities, they were completely heterochromatic (C-banding) and uniformly stained by 4’,6-diamidino-2-phenylindole (DAPI). Variations in the number of B chromosomes were detected between cells of the same individual, between individuals of the same colony, and between colonies from different localities.

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Short Communication Fri, 9 Nov 2018 21:04:20 +0200
Comparative cytogenetics and derived phylogenic relationship among Sitophilus grain weevils (Coleoptera, Curculionidae, Dryophthorinae) https://compcytogen.pensoft.net/article/26412/ Comparative Cytogenetics 12(2): 223-245

DOI: 10.3897/CompCytogen.v12i2.26412

Authors: Alexandra Avelar Silva, Lucas Soares Braga, Alberto Soares Corrêa, Valerie Renee Holmes, John Spencer Johnston, Brenda Oppert, Raul Narciso Carvalho Guedes, Mara Garcia Tavares

Abstract: Cytogenetic characteristics and genome size are powerful tools for species characterization and identification of cryptic species, providing critical insights into phylogenetic and evolutionary relationships. Sitophilus Linnaeus, 1758 grain weevils can benefit from such tools as key pest species of stored products and also as sources of archeological information on human history and past urban environments. Moreover, the phylogenetic relationship among these weevil species remains controversial and is largely based on single DNA fragment analyses. Therefore, cytogenetic analyses and genome size determinations were performed for four Sitophilus grain weevil species, namely the granary weevil Sitophilus granarius (Linnaeus, 1758), the tamarind weevil S. linearis (Herbst, 1797), the rice weevil S. oryzae (Linnaeus, 1763), and the maize weevil S. zeamais Motschulsky, 1855. Both maize and rice weevils exhibited the same chromosome number (2n=22; 10 A + Xyp). In contrast, the granary and tamarind weevils exhibited higher chromosome number (2n=24; 11 A + Xyp and 11 A + neo-XY, respectively). The nuclear DNA content of these species was not proportionally related to either chromosome number or heterochromatin amount. Maize and rice weevils exhibited similar and larger genome sizes (0.730±0.003 pg and 0.786±0.003 pg, respectively), followed by the granary weevil (0.553±0.003 pg), and the tamarind weevil (0.440±0.001 pg). Parsimony phylogenetic analysis of the insect karyotypes indicate that S. zeamais and S. oryzae were phylogenetically closer than S. granarius and S. linearis, which were more closely related and share a more recent ancestral relationship.

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Research Article Mon, 2 Jul 2018 15:26:54 +0300
Multidirectional chromosome painting in Synallaxis frontalis (Passeriformes, Furnariidae) reveals high chromosomal reorganization, involving fissions and inversions https://compcytogen.pensoft.net/article/22344/ Comparative Cytogenetics 12(1): 97-110

DOI: 10.3897/CompCytogen.v12i1.22344

Authors: Rafael Kretschmer, Vanusa Lilian Camargo de Lima, Marcelo Santos de Souza, Alice Lemos Costa, Patricia C. M. O’Brien, Malcolm A. Ferguson-Smith, Edivaldo Herculano Corrêa de Oliveira, Ricardo José Gunski, Analía Del Valle Garnero

Abstract: In this work we performed comparative chromosome painting using probes from Gallus gallus (GGA) Linnaeus, 1758 and Leucopternis albicollis (LAL) Latham, 1790 in Synallaxis frontalis Pelzeln, 1859 (Passeriformes, Furnariidae), an exclusively Neotropical species, in order to analyze whether the complex pattern of intrachromosomal rearrangements (paracentric and pericentric inversions) proposed for Oscines and Suboscines is shared with more basal species. S. frontalis has 82 chromosomes, similar to most Avian species, with a large number of microchromosomes and a few pairs of macrochromosomes. We found polymorphisms in pairs 1 and 3, where homologues were submetacentric and acrocentric. Hybridization of GGA probes showed syntenies in the majority of ancestral macrochromosomes, except for GGA1 and GGA2, which hybridized to more than one pair of chromosomes each. LAL probes confirmed the occurrence of intrachromosomal rearrangements in the chromosomes corresponding to GGA1q, as previously proposed for species from the order Passeriformes. In addition, LAL probes suggest that pericentric inversions or centromere repositioning were responsible for variations in the morphology of the heteromorphic pairs 1 and 3. Altogether, the analysis of our data on chromosome painting and the data published in other Passeriformes highlights chromosomal changes that have occurred during the evolution of Passeriformes.

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Research Article Tue, 13 Mar 2018 12:28:45 +0200
Molecular phylogenetic reconstruction and localization of the (TTAGG)n telomeric repeats in the chromosomes of Acromyrmex striatus (Roger, 1863) suggests a lower ancestral karyotype for leafcutter ants (Hymenoptera) https://compcytogen.pensoft.net/article/21799/ Comparative Cytogenetics 12(1): 13-26

DOI: 10.3897/CompCytogen.v12i1.21799

Authors: Tássia Tatiane Pontes Pereira, Ana Caroline Coelho Corrêa dos Reis, Danon Clemes Cardoso, Maykon Passos Cristiano

Abstract: Chromosome counts and karyotype characterization have proved to be important features of a genome. Chromosome changes during the diversification of ants might play an important role, given the diversity and success of Formicidae. Comparative karyotype analyses on ants have enriched and helped ant systematics. Among leafcutter ants, two major chromosome counts have been described, one frequent in Atta Fabricius, 1804 (2n = 22 in all Atta spp. whose karyotype is known) and the other frequent in Acromyrmex Mayr, 1865 (2n = 38 in the majority of species whose karyotype is known). The main exception is Acromyrmex striatus (Roger, 1863), which harbors a diploid chromosome set of 22. Here we describe the use of fluorescence in situ hybridization (FISH) with telomeric probes with (TTAGG)6 repeats to describe the telomere composition of A. striatus and to recover potential interstitial non-telomeric signals that may reflect fusion events during the evolution of leafcutter lineage from 38 to 22 chromosomes. Further, we reconstruct the ancestral chromosome numbers of the leafcutter clade based on a recently proposed molecular phylogenetic hypothesis and phylogenomic tree. Distinct signals have been observed in both extremities on the telomere chromosomes of A. striatus. Non-telomeric signals have not been retrieved in our analysis. It could be supposed that the low-numbered karyotype indeed represents the ancestral chromosome number of leafcutters. The phylogenetic reconstruction also recovered a low chromosome number from the diverse approaches implemented, suggesting that n = 11 is the most likely ancestral karyotype of the leafcutter ants and is a plesiomorphic feature shared between A. striatus and Atta spp.

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Research Article Tue, 9 Jan 2018 11:30:50 +0200
Studies in two allopatric populations of Hypostomus affinis (Steindachner, 1877): the role of mapping the ribosomal genes to understand the chromosome evolution of the group https://compcytogen.pensoft.net/article/22052/ Comparative Cytogenetics 12(1): 1-12

DOI: 10.3897/CompCytogen.v12i1.22052

Authors: Karina de Oliveira Brandão, Dinaíza Abadia Rocha-Reis, Caroline Garcia, Rubens Pazza, Lurdes Foresti de Almeida-Toledo, Karine Frehner Kavalco

Abstract: Several cytogenetic markers show chromosomal diversity in the fish such as “armoured catfish”. Although studies have characterized many species in the major genera representing these Siluridae, particularly in the genus Hypostomus Lacépède, 1803, trends in chromosome evolution of this group remain unclear. The Paraíba do Sul river basin contains the armoured catfish Hypostomus affinis Steindachner, 1877, which is unique because of its distribution of repetitive DNAs, the 5S and 18S rDNA. Identified samples and registered collections in Brazilian museums were identified as the same typological species, while we observed wide variations in the physical location of this gene in the karyotype based on fluorescent in situ hybridization results. In this study, we propose that these species can represent evolutionarily independent units, as these fish frequently undergo processes such as dispersion and vicariance and that the rDNA is associated with DNA that spreads in the genome, such as transposons. Additionally, the absence of gene flow due to the distance of the sample location could intensify evolutionary processes. The phenotypes found for the 18S rDNA showed minor changes in relation to the number of sites between the lower and upper drainage regions of Paraíba do Sul. The large difference in the number of sites found for the 5S rDNA entered the same region (upper drainage of the basin) and the literature data could represent a population dynamics where an expansion of the 5S rDNA sites provides an extinct or non-sampled cytotype in this work.

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Research Article Tue, 9 Jan 2018 11:30:03 +0200
Heterochromatin variation and LINE-1 distribution in Artibeus (Chiroptera, Phyllostomidae) from Central Amazon, Brazil https://compcytogen.pensoft.net/article/14562/ Comparative Cytogenetics 11(4): 613-626

DOI: 10.3897/CompCytogen.v11i4.14562

Authors: Érica Martinha Silva de Souza, Maria Claudia Gross, Carlos Eduardo Faresin Silva, Cibele G. Sotero-Caio, Eliana Feldberg

Abstract: Species in the subgenus Artibeus Leach, 1821 are widely distributed in Brazil. Conserved karyotypes characterize the group with identical diploid number and chromosome morphology. Recent studies suggested that the heterochromatin distribution and accumulation patterns can vary among species. In order to assess whether variation can also occur within species, we have analyzed the chromosomal distribution of constitutive heterochromatin in A. planirostris (Spix, 1823) and A. lituratus (Olfers, 1818) from Central Amazon (North Brazil) and contrasted our findings with those reported for other localities in Brazil. In addition, Ag-NOR staining and FISH with 18S rDNA, telomeric, and LINE-1 probes were performed to assess the potential role that these different repetitive markers had in shaping the current architecture of heterochromatic regions. Both species presented interindividual variation of constitutive heterochromatin. In addition, in A. planirostris the centromeres of most chromosomes are enriched with LINE-1, colocated with pericentromeric heterochromatin blocks. Overall, our data indicate that amplification and differential distribution of the investigated repetitive DNAs might have played a significant role in shaping the chromosome architecture of the subgenus Artibeus.

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Short Communication Thu, 14 Sep 2017 12:15:39 +0300
Cestrum strigilatum (Ruiz & Pavón, 1799) B chromosome shares repetitive DNA sequences with A chromosomes of different Cestrum (Linnaeus, 1753) species https://compcytogen.pensoft.net/article/13418/ Comparative Cytogenetics 11(3): 511-524

DOI: 10.3897/CompCytogen.v11i3.13418

Authors: André Luís Laforga Vanzela, Adriano Alves de Paula, Carolina Cristina Quintas, Thiago Fernandes, Joana Neres da Cruz Baldissera, Thaissa Boldieri de Souza

Abstract: Species of Cestrum (Linnaeus, 1753) have shown large diversity in the accumulation and distribution of repetitive DNA families, and B chromosomes have been described in seven species. Some types of repetitive DNA were identified in A and B chromosomes in species of this plant group, such as AT-rich SSR, 35S and 5S rDNA, C-Giemsa and C-CMA/DAPI bands and retrotransposons. To increase our understanding of the relationships of A and B chromosomes, the B of C. strigilatum Ruiz & Pavón, 1799 was microdissected, amplified and hybridized in situ against chromosomes of this species, and in six other species of this genus. FISH signals were observed in whole the B of C. strigilatum, including stretches of A chromosomes, as well as in some A chromosomes of all tested species. A strong FISH signal was seen adjacent to the 5S rDNA in the proximal region of pair 8 of all species and, due to this, we have searched for 5S rDNA fragments in the microdissected B chromosome. PCR and sequencing data evidenced 5S rDNA deletion along evolutionary pathways of the B of C. strigilatum. Although A and B chromosomes displayed redundancy in the repetitive DNA families in different species, the B of C. strigilatum seemed to differ from those Bs of other Cestrum species by the loss of rDNA fractions. A possible origin of Bs in Cestrum was discussed.

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Research Article Thu, 3 Aug 2017 11:08:34 +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
The Cerrado (Brazil) plant cytogenetics database https://compcytogen.pensoft.net/article/11395/ Comparative Cytogenetics 11(2): 285-297

DOI: 10.3897/CompCytogen.v11i2.11395

Authors: Fernando Roa, Mariana Pires de Campos Telles

Abstract: Cerrado is a biodiversity hotspot that has lost ca. 50% of its original vegetation cover and hosts ca. 11,000 species belonging to 1,423 genera of phanerogams. For a fraction of those species some cytogenetic characteristics like chromosome numbers and C-value were available in databases, while other valuable information such as karyotype formula and banding patterns are missing. In order to integrate and share all cytogenetic information published for Cerrado species, including frequency of cytogenetic attributes and scientometrics aspects, Cerrado plant species were searched in bibliographic sources, including the 50 richest genera (with more than 45 taxa) and 273 genera with only one species in Cerrado. Determination of frequencies and the database website (http://cyto.shinyapps.io/cerrado) were developed in R. Studies were pooled by employed technique and decade, showing a rise in non-conventional cytogenetics since 2000. However, C-value estimation, heterochromatin staining and molecular cytogenetics are still not common for any family. For the richest and best sampled families, the following modal 2n counts were observed: Oxalidaceae 2n = 12, Lythraceae 2n = 30, Sapindaceae 2n = 24, Solanaceae 2n = 24, Cyperaceae 2n = 10, Poaceae 2n = 20, Asteraceae 2n = 18 and Fabaceae 2n = 26. Chromosome number information is available for only 16.1% of species, while there are genome size data for only 1.25%, being lower than the global percentages. In general, genome sizes were small, ranging from 2C = ca. 1.5 to ca. 3.5 pg. Intra-specific 2n number variation and higher 2n counts were mainly related to polyploidy, which relates to the prevalence of even haploid numbers above the mode of 2n in most major plant clades. Several orphan genera with almost no cytogenetic studies for Cerrado were identified. This effort represents a complete diagnosis for cytogenetic attributes of plants of Cerrado.

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Data Paper Tue, 25 Apr 2017 14:19:46 +0300
Comparative analysis based on replication banding reveals the mechanism responsible for the difference in the karyotype constitution of treefrogs Ololygon and Scinax (Arboranae, Hylidae, Scinaxinae) https://compcytogen.pensoft.net/article/11254/ Comparative Cytogenetics 11(2): 267-283

DOI: 10.3897/CompCytogen.v11i2.11254

Authors: Simone Lilian Gruber, Gabriela Isabela Gomes de Oliveira, Ana Paula Zampieri Silva, Hideki Narimatsu, Célio Fernando Baptista Haddad, Sanae Kasahara

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

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Research Article Tue, 18 Apr 2017 14:21:55 +0300
Chromosome mapping in Abracris flavolineata (De Geer, 1773) (Orthoptera) from the Iguaçu National Park – Foz do Iguaçu, Paraná, Brazil https://compcytogen.pensoft.net/article/10282/ Comparative Cytogenetics 11(2): 203-212

DOI: 10.3897/compcytogen.v11i2.10282

Authors: Mariana Bozina Pine, Raquel Bozini Gallo, Carlos Roberto Maximiano da Silva, Larissa Forim Pezenti, Fernando Campos De Domenico, Vilma Loreto, Renata da Rosa

Abstract: In this paper, we present the cytomolecular analysis of a population of Abracris flavolineata collected in the largest fragment of the Brazilian Atlantic forest, the Iguaçu National Park. The diploid number in males was 23 (22+X0), with two large pairs (1–2), 7 medium (3–9), 2 small (10–11) and the X chromosome of medium size. Heterochromatic blocks were evident in the pericentromeric regions of all chromosomes. Heterogeneity in the distribution of heterochromatin was observed, with a predominance of DAPI+ blocks. However, some chromosomes showed CMA3+ blocks and other DAPI+/CMA3+ blocks. The 18S rDNA sites were distributed on the short arms of 5 pairs. In two of these pairs, such sites were in the same chromosome bearing 5S rDNA, and one of the bivalents, they were co-located. Histone H3 genes were found on one bivalent. The results added to the existing cytogenetic studies provided evidence of great karyotypic plasticity in the species. This pliancy may be the result of vicariant events related to the geographical distribution of different populations of A. flavolineata.

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Short Communication Fri, 31 Mar 2017 12:56:17 +0300
A cytogenetic study of three parasitic wasp species (Hymenoptera, Chalcidoidea, Eulophidae, Trichogrammatidae) from Brazil using chromosome morphometrics and base-specific fluorochrome staining https://compcytogen.pensoft.net/article/11706/ Comparative Cytogenetics 11(1): 179-188

DOI: 10.3897/CompCytogen.v11i1.11706

Authors: Vladimir E. Gokhman, Fabricio Fagundes Pereira, Marco Antonio Costa

Abstract: Chromosomes of three chalcid wasp species from Brazil, Palmistichus elaeisis Delvare et LaSalle, 1993, Trichospilus diatraeae Cherian et Margabandhu, 1942 (both belonging to the family Eulophidae) and Trichogramma pretiosum Riley, 1879 (Trichogrammatidae), were studied using chromosome morphometrics and base-specific fluorochrome staining. The present study confirmed that these species respectively have 2n = 12, 14 and 10. Chromomycin A3 / 4’, 6-diamidino-2-phenylindole (CMA3/DAPI) staining revealed a single CMA3-positive and DAPI-negative band within haploid karyotypes of both P. elaeisis and T. pretiosum. This CG-rich band clearly corresponds to the nucleolus organizing region (NOR). Moreover, analogous multiple telomeric bands found on all chromosomes of T. diatraeae may also represent NORs. Certain features of karyotype evolution of the phylogenetic lineage comprising both Eulophidae and Trichogrammatidae are discussed. The results obtained during the present study demonstrate the importance of chromosome research on tropical parasitoids that remain poorly known in this respect.

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Research Article Fri, 17 Mar 2017 14:27:23 +0200
First karyotype description and nuclear 2C value for Myrsine (Primulaceae): comparing three species https://compcytogen.pensoft.net/article/11601/ Comparative Cytogenetics 11(1): 163-177

DOI: 10.3897/CompCytogen.v11i1.11601

Authors: Renata Flávia de Carvalho, Paulo Marcos Amaral-Silva, Micheli Sossai Spadeto, Andrei Caíque Pires Nunes, Tatiana Tavares Carrijo, Carlos Roberto Carvalho, Wellington Ronildo Clarindo

Abstract: Cytogenetic studies in Primulaceae are mostly available for herbaceous species, and are focused on the chromosome number determination. An accurate karyotype characterization represents a starting point to know the morphometry and class of the chromosomes. Comparison among species within Myrsine, associating these data with the nuclear 2C value, can show changes that led the karyotype evolution. Here, we studied three Myrsine species [Myrsine coriacea (Swartz, 1788) Brown ex Roemer et Schultes, 1819, Myrsine umbellata Martius, 1841 and Myrsine parvifolia Candolle, 1841] that show different abilities to occupy the varied types of vegetation within the Brazilian Atlantic Forest. Cytogenetic characterization showed some individuals with 2n = 45 chromosomes for M. parvifolia and M. coriacea, with most individuals of the three species having 2n = 46. The first karyograms for Myrsine were assembled and presented morphologically identical and distinct chromosome pairs. In addition, differences in the mean 2C nuclear value and chromosome morphometry were found. Therefore, the first description of the Myrsine karyotype has been presented, as well as the nuclear 2C value. The procedures can be applied to other Myrsine species for future investigations in order to better understand its effects on the differential spatial occupation abilities shown by the species in Brazilian Atlantic Forest.

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Research Article Mon, 13 Mar 2017 11:51:41 +0200
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
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
Analysis of the karyotype structure in Ricolla quadrispinosa (Linneus, 1767): inferences about the chromosomal evolution of the tribes of Harpactorinae (Heteroptera, Reduviidae) https://compcytogen.pensoft.net/article/10392/ Comparative Cytogenetics 10(4): 719-729

DOI: 10.3897/CompCytogen.v10i4.10392

Authors: Angélica Nunes Tiepo, Larissa Forim Pezenti, Thayná Bisson Ferraz Lopes, Carlos Roberto Maximiano da Silva, Jaqueline Fernanda Dionísio, José Antônio Marin Fernandes, Renata Da Rosa

Abstract: The subfamily Harpactorinae is composed of six tribes. Phylogenetic studies bring together some of Harpactorinae tribes, but by and large the data on evolutionary relationships of the subfamily are scarce. Chromosome studies are of great importance for understanding the systematics of different groups of insects. For Harpactorinae, these studies are restricted to some subfamilies and involved only conventional chromosome analysis. This work analyzed cytogenetically Ricolla quadrispinosa (Linneus, 1767). The chromosome number was determined as 2n = 24 + X1X2Y in males. In metaphase II the autosomal chromosomes were organized in a ring with the pseudo-trivalent of sex chromosomes in its center. After C-banding followed by staining with DAPI, AT-rich blocks in autosomes were observed and the negatively heteropycnotic sex chromosomes. The data obtained, together with existing data for other species of the group, indicated that different chromosomal rearrangements are involved in the evolution of the species. In addition, a proposal of karyotype evolution for the subfamily, based on existing phylogenetic studies for the group is presented.

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Research Article Fri, 9 Dec 2016 16:50:15 +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
Karyological study of Ololygon tripui (Lourenço, Nascimento and Pires, 2009), (Anura, Hylidae) with comments on chromosomal traits among populations https://compcytogen.pensoft.net/article/9176/ Comparative Cytogenetics 10(4): 505-516

DOI: 10.3897/CompCytogen.v10i4.9176

Authors: Marco Antônio A. Peixoto, Marina P.C. Oliveira, Renato N. Feio, Jorge A. Dergam

Abstract: To increase the number of cytogenetic characters used in Ololygon tripui systematics, we applied some cytogenetic techniques such as Giemsa, C- and NOR-banding, and fluorescence in situ hybridization (FISH) with 18S rDNA and repetitive microsatellite DNA probes to the study of four populations from Minas Gerais State (southeastern Brazil). All populations showed 2n = 24 and FN = 48, and chromosomal formula 8m + 10sm + 6st. Nucleolar organizing regions (NORs) were located on chromosome pair 6 in all populations, although in the Tripuí locality additional markings were observed on one homologue of chromosome pair 3. These patterns were partially congruent with results obtained using the 18S rDNA FISH probe. The microsatellites repetitive DNA (GA)15 and (CAT)10 probes accumulated predominantly in the terminal region of all chromosomes. Chromosome morphology and Ag-NOR were conserved among populations, a conserved pattern in Ololygon Fitzinger, 1843. Repetitive DNA FISH probes patterns were similar among populations, but they revealed species-specific differences when compared with other species of the genus Ololygon, suggesting that molecular cytogenetics are potentially more informative in karyologically conservative taxa.

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Research Article Mon, 10 Oct 2016 15:35:12 +0300
Meiotic behavior and H3K4m distribution in B chromosomes of Characidium gomesi (Characiformes, Crenuchidae) https://compcytogen.pensoft.net/article/7939/ Comparative Cytogenetics 10(2): 255-268

DOI: 10.3897/CompCytogen.v10i2.7939

Authors: Érica Alves Freitas, Cristian Araya-Jaime, Elkin Suárez-Villota, Claudio Oliveira, Fausto Foresti

Abstract: Characidium gomesi Travasso, 1956 specimens from the Pardo River have up to four heterochromatic supernumerary chromosomes, derived from the sex chromosomes. To access the meiotic behavior and distribution of an active chromatin marker, males and females of C. gomesi with two or three B chromosomes were analyzed. Mitotic chromosomes were characterized using C-banding and FISH with B chromosome probes. Meiocytes were subjected to immunofluorescence-FISH assay using anti-SYCP3, anti-H3K4m, and B chromosomes probes. Molecular homology of supernumeraries was confirmed by FISH and by its bivalent conformation in individuals with two of these chromosomes. In individuals with three Bs, these elements formed a bivalent and a univalent. Supernumerary and sex chromosomes exhibited H3K4m signals during pachytene contrasting with their heterochromatic and asynaptic nature, which suggest a more structural role than functional of this histone modification. The implications of this result are discussed in light of the homology, meiotic nuclear organization, and meiotic silencing of unsynapsed chomatin.

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Research Article Wed, 18 May 2016 11:12:56 +0300
Organization of some repetitive DNAs and B chromosomes in the grasshopper Eumastusia koebelei koebelei (Rehn, 1909) (Orthoptera, Acrididae, Leptysminae) https://compcytogen.pensoft.net/article/7609/ Comparative Cytogenetics 10(2): 219-228

DOI: 10.3897/CompCytogen.v10i2.7609

Authors: Allison Anjos, Vilma Loreto, Diogo C. Cabral-de-Mello

Abstract: B chromosomes occur in approximately 15% of eukaryotes and are usually heterochromatic and rich in repetitive DNAs. Here we describe characteristics of a B chromosome in the grasshopper Eumastusia koebelei koebelei (Rehn, 1909) through classical cytogenetic methods and mapping of some repetitive DNAs, including multigene families, telomeric repeats and a DNA fraction enriched with repetitive DNAs obtained from DOP-PCR. Eumastusia k. koebelei presented 2n=23, X0 and, in one individual, two copies of the same variant of a B chromosome were noticed, which are associated during meiosis. The C-positive blocks were located in the pericentromeric regions of the standard complement and along the entire length of the B chromosomes. Some G+C-rich heterochromatic blocks were noticed, including conspicuous blocks in the B chromosomes. The mapping of 18S rDNA and U2 snDNA revealed only autosomal clusters, and the telomeric probe hybridized in terminal regions. Finally, the DOP-PCR probe obtained from an individual without a B chromosome revealed signals in the heterochromatic regions, including the entire length of the B chromosome. The possible intraspecific origin of the B chromosomes, due to the shared pool of repetitive DNAs between the A and B chromosomes and the possible consequences of their association are discussed.

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Research Article Wed, 6 Apr 2016 10:14:25 +0300
Karyotype and genome size in Euterpe Mart. (Arecaceae) species https://compcytogen.pensoft.net/article/5522/ Comparative Cytogenetics 10(1): 17-25

DOI: 10.3897/CompCytogen.v10i1.5522

Authors: Ludmila Cristina Oliveira, Maria do Socorro Padilha de Oliveira, Lisete Chamma Davide, Giovana Augusta Torres

Abstract: Euterpe (Martius, 1823), a genus from Central and South America, has species with high economic importance in Brazil, because of their palm heart and fruits, known as açaí berries. Breeding programs have been conducted to increase yield and establish cultivation systems to replace the extraction of wild material. These programs need basic information about the genome of these species to better explore the available genetic variability. The aim of this study was to compare E. edulis (Martius, 1824), E. oleracea (Martius, 1824) and E. precatoria (Martius, 1842), with regard to karyotype, type of interphase nucleus and nuclear DNA amount. Metaphase chromosomes and interphase nuclei from root tip meristematic cells were obtained by the squashing technique and solid stained for microscope analysis. The DNA amount was estimated by flow cytometry. There were previous reports on the chromosome number of E. edulis and E. oleracea, but chromosome morphology of these two species and the whole karyotype of E. precatoria are reported for the first time. The species have 2n=36, a number considered as a pleisomorphic feature in Arecoideae since the modern species, according to floral morphology, have the lowest chromosome number (2n=28 and 2n=30). The three Euterpe species also have the same type of interphase nuclei, classified as semi-reticulate. The species differed on karyotypic formulas, on localization of secondary constriction and genome size. The data suggest that the main forces driving Euterpe karyotype evolution were structural rearrangements, such as inversions and translocations that alter chromosome morphology, and either deletion or amplification that led to changes in chromosome size.

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Research Article Fri, 22 Jan 2016 11:46:38 +0200
Cytogenetic analysis of Scinax auratus and Scinax eurydice (Anura, Hylidae) with emphasis on cytotaxonomy https://compcytogen.pensoft.net/article/4593/ Comparative Cytogenetics 9(2): 227-236

DOI: 10.3897/CompCytogen.v9i2.4593

Authors: Lidia Nogueira, Fabilene Paim, Débora Diniz, Mirco Sole, Paulo Roberto Affonso, Sérgio Siqueira, Iracilda Sampaio

Abstract: Scinax Wagler, 1830 is a species-rich genus of amphibians with relatively few detailed chromosomal reports. In this work, cytogenetic analyses of Scinax auratus (Wied-Neuwied, 1821) and Scinax eurydice (Bokermann, 1968) were carried out based on conventional (Giemsa staining, Ag-NOR and C-banding) and cytomolecular (base-specific fluorochrome staining and fluorescence in situ hybridization – FISH of ribosomal probes) techniques. Both species shared the same karyotype, location of active nucleolar organizer regions on pair 11 and GC-rich heterochromatin, as reported for most species in S. ruber clade. Interpopulation chromosomal variation was observed in S. eurydice, indicating the occurrence of cryptic species. The mapping of 18S ribosomal genes by FISH is reported for the first time in both species.

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Short Communication Tue, 26 May 2015 11:51:02 +0300
Cytogenetic analyses using C-banding and DAPI/CMA3 staining of four populations of the maize weevil Sitophilus zeamais Motschulsky, 1855 (Coleoptera, Curculionidae) https://compcytogen.pensoft.net/article/4611/ Comparative Cytogenetics 9(1): 89-102

DOI: 10.3897/CompCytogen.v9i1.4611

Authors: Alexandra A. da Silva, Lucas S. Braga, Raul Narciso C. Guedes, Mara G. Tavares

Abstract: Cytogenetic data avalaible for the maize weevil Sitophilus zeamais Motschulsky, 1855 (Coleoptera: Curculionidae), one of the most destructive pests of stored cereal grains, are controversial. Earlier studies focused on single populations and emphasized chromosome number and sex determination system. In this paper, the karyotypes of four populations of S. zeamais were characterized by conventional staining, C-banding and sequential staining with the fluorochromes chromomycin-A3/4-6-diamidino-2-phenylindole (CMA3/DAPI). The analyses of metaphases obtained from the cerebral ganglia of last instar larvae and the testes of adults showed that the species had 2n = 22 chromosomes, with 10 autosomal pairs and a sex chromosome pair (XX in females and Xyp in males). Chromosome number, however, ranged from 2n = 22 to 26 due to the presence of 0–4 supernumerary chromosomes in individuals from the populations of Viçosa, Unai and Porto Alegre. With the exception of the Y chromosome, which was dot-like, all other chromosomes of this species were metacentric, including the supernumeraries. The heterochromatin was present in the centromeric regions of all autosomes and in the centromere of the X chromosome. The B chromosomes were partially or totally heterochromatic, and the Y chromosome was euchromatic. The heterochromatic regions were labeled with C-banding and DAPI, which showed that they were rich in AT base pairs.

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Research Article Tue, 31 Mar 2015 16:55:34 +0300
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 diversity among predatory Reduviidae (Heteroptera) https://compcytogen.pensoft.net/article/4361/ Comparative Cytogenetics 8(4): 351-367

DOI: 10.3897/CompCytogen.v8i4.8430

Authors: Vanessa Bellini Bardella, Hélcio Reinaldo Gil-Santana, Francisco Panzera, André Luís Laforga Vanzela

Abstract: Species of infraorder Cimicomorpha of Heteroptera exhibit holokinetic chromosomes with inverted meiosis for sex chromosomes and high variation in chromosome number. The family Reduviidae, which belongs to this infraorder, is also recognized by high variability of heterochromatic bands and chromosome location of 18S rDNA loci. We studied here five species of Reduviidae (Harpactorinae) with predator habit, which are especially interesting because individuals are found solitary and dispersed in nature. These species showed striking variation in chromosome number (including sex chromosome systems), inter-chromosomal asymmetry, different number and chromosome location of 18S rDNA loci, dissimilar location and quantity of autosomal C-heterochromatin, and different types of repetitive DNA by fluorochrome banding, probably associated with occurrence of different chromosome rearrangements. Terminal chromosome location of C-heterochromatin seems to reinforce the model of equilocal dispersion of repetitive DNA families based in the “bouquet configuration”.

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Research Article Thu, 18 Dec 2014 00:00:00 +0200
Karyotype diversity and patterns of chromosomal evolution in Eigenmannia (Teleostei, Gymnotiformes, Sternopygidae) https://compcytogen.pensoft.net/article/4250/ Comparative Cytogenetics 8(4): 301-311

DOI: 10.3897/CompCytogen.v8i4.8396

Authors: Viviane França Sene, José Carlos Pansonato-Alves, Ricardo Utsunomia, Claudio Oliveira, Fausto Foresti

Abstract: Conventional (Giemsa, C-banding, Ag – NORs) and molecular [5S rDNA, 18S rDNA, (TTAGGG)n] cytogenetic techniques were employed to study six species of the genus Eigenmannia Jordan & Evermann, 1896. They exhibited diploid chromosome numbers ranging from 2n=28 (Eigenmannia sp.1) to 2n=38 (E. virescens (Valenciennes, 1836)). The C-banding results revealed that species with the lowest 2n have less heterochromatin content and that morphologically differentiated sex chromosomes observed in two species showed distinct patterns of heterochromatin. While the X1, X2 and Y-chromosomes of Eigenmannia sp.2 showed only centromeric heterochromatin, the XY sex chromosomes of E. virescens possessed large heterochromatic blocks in the terminal position, particularly on the X chromosome. The nucleolus organizer regions (NORs) were located in different positions when compared to the 5S rDNA sites. Additionally, the presence of minor ribosomal gene sites on the sex chromosome pair of E. virescens represented a new type of the sex chromosomes in this group. The telomeric probe (TTAGGG)n hybridized to the terminal portion of all chromosomes in all species examined however, interstitial telomeric sites were found in the metacentric pair No. 2 in Eigenmannia sp.1. The analyzes confirmed some hypotheses about karyotype evolution in the genus Eigenmannia, and brought new information about the distribution of the genetic material in the chromosomes of the samples analyzed providing new insights for understanding the process differentiation in the genomes of species under study.

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Research Article Mon, 17 Nov 2014 00:00:00 +0200
Cytogenetics of Melitoma segmentaria (Fabricius, 1804) (Hymenoptera, Apidae) reveals differences in the characteristics of heterochromatin in bees https://compcytogen.pensoft.net/article/1816/ Comparative Cytogenetics 8(3): 223-231

DOI: 10.3897/compcytogen.v8i3.7510

Authors: Maykon P Cristiano, Tallita Guimarães Simões, Denilce Menezes Lopes, Silvia das Graças Pompolo

Abstract: To date, more than 65 species of Brazilian bees (of the superfamily Apoidea) have been cytogenetically studied, but only a few solitary species have been analyzed. One example is the genus Melitoma Lepeletier & Serville, 1828, for which there is no report in the literature with regard to cytogenetic studies. The objective of the present study is to analyze the chromosome number and morphology of the species Melitoma segmentaria (Fabricius, 1804), as well as to determine the pattern of heterochromatin distribution and identify the adenine–thymine (AT)- and guanine–cytosine (GC)-rich regions. Melitoma segmentaria presents chromosome numbers of 2n=30 (females) and n=15 (males). With C-banding, it is possible to classify the chromosomes into seven pseudo-acrocentric pairs (AM), seven pseudo-acrocentric pairs with interstitial heterochromatin (AMi), and one totally heterochromatic metacentric pair (Mh). Fluorochrome staining has revealed that heterochromatin present in the chromosomal arms is rich in GC base pairs (CMA3+) and the centromeric region is rich in AT base pairs (DAPI+). The composition found for Melitoma diverges from the pattern observed in other bees, in which the heterochromatin is usually rich in AT. In bees, few heterochromatic regions are rich in GC and these are usually associated with or localized close to the nucleolus organizer regions (NORs). Silver nitrate impregnation marks the heterochromatin present in the chromosome arms, which makes identification of the NOR in the chromosomes impossible. As this technique reveals proteins in the NOR, the observation that is made in the present study suggests that the proteins found in the heterochromatin are qualitatively similar to those in the NOR.

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Research Article Thu, 14 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
Possible interspecific origin of the B chromosome of Hypsiboas albopunctatus (Spix, 1824) (Anura, Hylidae), revealed by microdissection, chromosome painting, and reverse hybridisation https://compcytogen.pensoft.net/article/1819/ Comparative Cytogenetics 8(3): 185-197

DOI: 10.3897/compcytogen.v8i3.7771

Authors: Simone Gruber, Débora Diniz, Patrícia Sobrinho-Scudeler, Fausto Foresti, Celio Haddad, Sanae Kasahara

Abstract: The B chromosome in the hylid Hypsiboas albopunctatus (2n = 22 + B) is small, almost entirely composed of C-positive heterochromatin, and does not pair with any chromosome of the A complement. B probe, obtained by microdissection and DOP-PCR amplification, was used to search for homology between the B and regular chromosomes of H. albopunctatus and of the related species H. raniceps (Cope, 1862). Reverse hybridisation was also carried out in the investigation. The B probe exclusively painted the supernumerary, not hybridising any other chromosomes in H. albopunctatus, but all H. raniceps chromosomes showed small labelling signals. This result might be an indication that differences exist between the repetitive sequences of A and B chromosomes of H. albopunctatus, and that the chromosomes of H. raniceps and the heterochromatin of the B chromosome of H. albopunctatus are enriched with the same type of repetitive DNA. In meiotic preparations, the B labelled about 30% of scored spermatids, revealing a non-mendelian inheritance, and the painted B in micronucleus suggests that the supernumerary is eliminated from germ line cells. Although our results could suggest an interespecific origin of the B at first sight, further analysis on its repetitive sequences is still necessary. Nevertheless, the accumulation of repetitive sequences, detected in another species, even though closely related, remains an intriguing question.

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Research Article Fri, 8 Aug 2014 00:00:00 +0300
New karyologycal data and cytotaxonomic considerations on small mammals from Santa Virgínia (Parque Estadual da Serra do Mar, Atlantic Forest, Brazil) https://compcytogen.pensoft.net/article/1807/ Comparative Cytogenetics 8(1): 11-30

DOI: 10.3897/compcytogen.v8i1.6430

Authors: Camilla Di-Nizo, Carolina Neves, Júlio Fernando Vilela, Maria José de J. Silva

Abstract: Atlantic Forest, in the eastern coast of Brazil, is a hotspot of biodiversity of mammals, and Parque Estadual da Serra do Mar (PESM) is the largest continuous area of this biome. Here, we characterized the karyotype composition of the small mammals from Santa Virgínia, a region in the northern part of PESM. Specimens were collected from July 2008 to September 2009. We identified 17 species (13 rodents and 4marsupials) from which 7 exhibited species-specific karyotypes, illustrating the importance of karyotype information in cytotaxonomy. We report for first time the karyotype of Monodelphis scalops (Thomas, 1888) and two new records for PESM: Akodon montensis Thomas, 1913 and Brucepattersonius soricinus Hershkovitz, 1998. Cytogenetic polymorphisms were detected for some species trapped in the area. Our results show the importance of Santa Virgínia / PESM in addressing studies for the conservation of small mammal wildlife in the Atlantic Forest.

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Research Article Fri, 24 Jan 2014 00:00:00 +0200
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
Cytogenetics of the Porthole Shovelnose Catfish, Hemisorubim platyrhynchos (Valenciennes, 1840) (Siluriformes, Pimelodidae), a widespread species in South American rivers https://compcytogen.pensoft.net/article/1793/ Comparative Cytogenetics 7(2): 103-110

DOI: 10.3897/compcytogen.v7i2.4901

Authors: Ana Swarça, Sebastian Sanchez, A. L. Dias, Alberto Fenocchio

Abstract: Hemisorubim platyrhynchos is a medium- to large-sized pimelodid catfish distributed along several river basins of the Neotropical Region, noteworthy for representing an important fishery source. In this work, H. platyrhynchos from three isolated populations were cytogenetically analyzed. The karyotype shows a diploid number of 2n=56 chromosomes comprising 22m, 16sm, 10st, 8a (FN=104). NORs detected by AgNO3 were located in the terminal regions of the short arm of a st chromosome pair, as confirmed by CMA3 and FISH using an 18S rDNA probe. C-banding revealed a small amount of heterochromatin in chromosomes, including the NORs, and one biarmed pair that showed conspicuous positive bands on both arms. This fact was also evidenced when using other banding techniques, such as RE (AluI), and indicates that this pair constitutes a species-specific cytogenetic marker.

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Research Article Thu, 25 Apr 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
Comparative cytogenetics of two species of genus Scobinancistrus (Siluriformes, Loricariidae, Ancistrini) from the Xingu River, Brazil https://compcytogen.pensoft.net/article/1782/ Comparative Cytogenetics 7(1): 43-51

DOI: 10.3897/compcytogen.v7i1.4128

Authors: Adauto Cardoso, Karline Sales, Cleusa Nagamachi, Julio Pieczarka, Renata Noronha

Abstract: The family Loricariidae encompasses approximately 800 species distributed in six subfamilies. The subfamily Hypostominae consists of five tribes; of them, the tribe Ancistrini is relatively diverse, but it is not well known from the cytogenetic point of view. Genus Scobinancistrus Isbrücker et Nijssen, 1989, which is part of the tribe Ancistrini, has two species that occur in sympatry in the Xingu River, Brazil. In this work, we performed the first karyotypic characterizations of these two species and sought to identify the processes involved in their karyotypic evolution. Chromosomal preparations were subjected to Giemsa staining, silver nitrate impregnation, C-banding, CMA3 staining, DAPI staining, and FISH (fluorescence in situ hybridization) with 18S rDNA and telomeric probes. We found that S. aureatus Burgess, 1994 and S. pariolispos Isbrücker et Nijssen, 1989 shared the diploid number, 2n=52, but differed in their karyotypic formulae (KFs), distribution of constitutive heterochromatin (CH), and the localizations of their nucleolus organizer regions (NORs), which were found on the interstitial and distal regions of the long arm of chromosome pair 3 in S. aureatus and S. pariolispos respectively. We suggest that these interspecific variations may have arisen via paracentric inversion or transposition of the NOR. The karyotypic differences found between these two Scobinancistrus species can be used to identify them taxonomically, and may have functioned as a mechanism of post-zygotic reproductive isolation during the speciation process.

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Research Article Mon, 18 Mar 2013 00:00:00 +0200
Cytogenetic description of the Amazonian brown brocket Mazama nemorivaga (Artiodactyla, Cervidae) https://compcytogen.pensoft.net/article/1784/ Comparative Cytogenetics 7(1): 25-31

DOI: 10.3897/compcytogen.v7i1.4314

Authors: Bruno Ferreto Fiorillo, Javier Adolfo Sarria-Perea, VanessaVeltrini Abril, José Maurício Barbanti Duarte

Abstract: The Amazonian brown brocket Mazama nemorivaga (Cuvier, 1817) is a small to medium-sized deer from the Amazon rainforest and ecotones. The first karyotype described was 2n=67 to 69 + 2-7 B and FN= 69-72, in which all chromosomes were acrocentric and the X chromosome was the only submetacentric chromosome. However, important aspects of the species chromosome evolution were not resolved because of the lack of information on chromosome banding. The G-banding pattern of M. nemorivaga karyotype showed the presence of an XX/XY1Y2 sex chromosome system as a product of an X-autosome tandem fusion, which results in a basic 2n=68, FN=70 in females and 2n= 69, FN=70 in males. The fact that this karyotype only differs from that of Capreolus capreolus pygargus (Pallas, 1771; 2n=70, FN=72+B) by X-autosome tandem fusion may corroborate the basal condition of M. nemorivaga and its proximity to the ancestral karyotype of the American Odocoileini. A derived karyotype 2n=67, XY1Y2, FN=70 + 3B from the Brazilian state of Mato Grosso (the western Amazon) may be evidence of differentiation between western and eastern populations.

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Research Article Mon, 18 Mar 2013 00:00:00 +0200
Karyotypic diversity and evolutionary trends in the Neotropical catfish genus Hypostomus Lacépède, 1803 (Teleostei, Siluriformes, Loricariidae) https://compcytogen.pensoft.net/article/1768/ Comparative Cytogenetics 6(4): 443-452

DOI: 10.3897/compcytogen.v6i4.4028

Authors: Anderson Alves, Rafael de Borba, Claudio Oliveira, Mauro Nirchio, Ángel Granado, Fausto Foresti

Abstract: The family Loricariidae with 813 nominal species is one of the largest fish families of the world. Hypostominae, its more complex subfamily, was recently divided into five tribes. The tribe Hypostomini is composed of a single genus, Hypostomus Lacépède, 1803, which exhibits the largest karyotypic diversity in the family Loricariidae. With the main objective of contributing to a better understanding of the relationship and the patterns of evolution among the karyotypes of Hypostomus species, cytogenetic studies were conducted in six species of the genus from Brazil and Venezuela. The results show a great chromosome variety with diploid numbers ranging from 2n=68 to 2n=76, with a clear predominance of acrocentric chromosomes. The Ag-NORs are located in terminal position in all species analyzed. Three species have single Ag-NORs (Hypostomus albopunctatus (Regan, 1908), H. prope plecostomus (Linnaeus, 1758), and H. prope paulinus (Ihering, 1905)) and three have multiple Ag-NORs (H. ancistroides (Ihering, 1911), H. prope iheringi (Regan, 1908), and H. strigaticeps (Regan, 1908)). In the process of karyotype evolution of the group, the main type of chromosome rearrangements was possibly centric fissions, which may have been facilitated by the putative tetraploid origin of Hypostomus species. The relationship between the karyotype changes and the evolution in the genus is discussed.

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Short Communication Sat, 15 Dec 2012 00:00:00 +0200
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
Localization of 18S ribosomal genes in suckermouth armoured catfishes Loricariidae (Teleostei, Siluriformes) with discussion on the Ag-NOR evolution https://compcytogen.pensoft.net/article/1759/ Comparative Cytogenetics 6(3): 315-321

DOI: 10.3897/compcytogen.v6i3.2667

Authors: Anderson Alves, Rafael de Borba, Allan Pozzobon, Claudio Oliveira, Mauro Nirchio, Ángel Granado, Fausto Foresti

Abstract: The family Loricariidae with about 690 species divided into six subfamilies, is one of the world’s largest fish families. Cytogenetic studies conducted in the family showed that among 90 species analyzed the diploid number ranges from 2n=38 in Ancistrus sp. to 2n=96 in Hemipsilichthys gobio Luetken, 1874. In the present study, fluorescence in situ hybridization (FISH) was employed to determine the chromosomal localization of the 18S rDNA gene in four suckermouth armoured catfishes: Kronichthys lacerta (Nichols, 1919), Pareiorhaphis splendens (Bizerril, 1995), Liposarcus multiradiatus (Hancock, 1828) and Hypostomus prope plecostomus (Linnaeus, 1758). All species analyzed showed one chromosome pair with 18S rDNA sequences, as observed in the previous Ag-NORs analyses. The presence of size and numerical polymorphism was observed and discussed, with proposing a hypothesis of the Ag-NOR evolution in Loricariidae.

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Research Article Wed, 26 Sep 2012 00:00:00 +0300
A new karyotype for Rhipidomys (Rodentia, Cricetidae) from Southeastern Brazil https://compcytogen.pensoft.net/article/1766/ Comparative Cytogenetics 6(3): 227-237

DOI: 10.3897/compcytogen.v6i3.2432

Authors: Ana Heloisa Carvalho, Maria Olimpia Lopes, Marta Svartman

Abstract: In this work we present a new karyotype for Rhipidomys Tschudi, 1845 (Cricetidae, Rodentia) from Brazil. Our chromosome analyses included GTG- and CBG-banding patterns, the localization of the nucleolus organizer regions after silver staining (Ag-NORs) and fluorescence in situ hybridization (FISH) with a telomere probe. The new karyotype is composed of 44 chromosomes and has a fundamental number (number of autosomal arms) of 48. Most Rhipidomys species already karyotyped presented similar complements with 2n=44, but their fundamental numbers varied from FN=46 to 80, a variation that has been mainly attributed to pericentric inversions. The comparison of this new karyotype to those of other Rhipidomys already reported allowed us to conclude that it is a distinctive chromosome complement, which can be of great use as a tool for the very complicated taxonomic identification in this genus.

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Research Article Mon, 9 Jul 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
A new karyotype for the spiny rat Clyomys laticeps (Thomas, 1909) (Rodentia, Echimyidae) from Central Brazil https://compcytogen.pensoft.net/article/1753/ Comparative Cytogenetics 6(2): 153-161

DOI: 10.3897/compcytogen.v6i2.1980

Authors: Alexandra M. R. Bezerra, Juliana Pagnozzi, Ana Paula Carmignotto, Yatiyo Yonenaga-Yassuda, Flávio Rodrigues

Abstract: Clyomys Thomas, 1916 is a semifossorial rodent genus of spiny rats represented by only one species, C. laticeps, which inhabits the tropical savannas and grasslands of central Brazil and eastern Paraguay. Here we describe a new karyotype of C. laticeps found in populations of Emas National Park, Goiás state, Brazil. The four analyzed specimens had a diploid number (2n) of 32 and a fundamental autosome number (FN) of 54. Cytogenetic data include conventional staining, CBG and GTG-banding. The karyotype presents 12 meta/submetacentric pairs (1 to 12) and 3 pairs of acrocentrics (13 to 15) with gradual decrease in size. The X chromosome is a medium submetacentric and the Y is a medium acrocentric. The semifossorial habits together with habitat specificity could have contributed to the karyological variations found on this genus.

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Research Article Mon, 9 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
First cytogenetic characterization of a species of the arboreal ant genus Azteca Forel, 1978 (Dolichoderinae, Formicidae) https://compcytogen.pensoft.net/article/1757/ Comparative Cytogenetics 6(2): 107-114

DOI: 10.3897/compcytogen.v6i2.2397

Authors: Danon Cardoso, Maykon P Cristiano, Luísa Barros, Denilce Lopes, Silvia Pompolo

Abstract: In this paper we present, for the first time, a detailed karyotype characterization of a species of the genus Azteca (Dolichoderinae, Formicidae). Cerebral ganglia from Azteca trigona Emery, 1893 were excised and submitted to colchicine hypotonic solution and chromosomal preparations were analyzed through conventional staining with Giemsa, C-banding, silver nitrate staining (AgNO3) and sequential base-specific fluorochromes. The analysis shows that A. trigona has a diploid number of 28 chromosomes. The karyotype consists of five metacentric pairs, seven acrocentric pairs and two pseudo-acrocentric pairs, which represents a karyotype formula 2K= 10M + 14A + 4AM and a diploid number of the arms 2AN = 38. The analysis of heterochromatin distribution revealed a positive block on distal region of the short arm of fourth metacentric pair, which was coincident with Ag-NOR band and CMA3 fluorochrome staining, meaning that rDNA sequences are interspaced by GC-rich base pairs sequences. The C-banding also marked short arms of other chromosomes, indicating centric fissions followed by heterochromatin growth. The karyotype analysis of A. trigona allowed the identification of cytogenetic markers that will be helpful in a difficult taxonomic group as Azteca and discussion about evolutionary aspects of the genome organization.

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Research Article Fri, 16 Mar 2012 00:00:00 +0200
Cytogenetic analysis in the incertae sedis species Astyanax altiparanae Garutti and Britzki, 2000 and Hyphessobrycon eques Steindachner, 1882 (Characiformes, Characidae) from the upper Paraná river basin https://compcytogen.pensoft.net/article/1745/ Comparative Cytogenetics 6(1): 41-51

DOI: 10.3897/compcytogen.v6i1.1873

Authors: Emanuel Martinez, Anderson Alves, Sara M Silveira, Fausto Foresti, Claudio Oliveira

Abstract: Cytogenetic analyses were accomplished in two populations of Astyanax altiparanae Garutti & Britzki, 2000 and one population of Hyphessobrycon eques Steindachner, 1882, considered incertae sedis in Characidae family. Two populations of A. altiparanae (Mogi-Guaçu and Tietê rivers) presented 2n=50, with the same karyotype formula: 6M+12SM+20ST+12A (FN=88). H. eques from Capivara river presented 2n=52 and karyotype formula 14M+16SM+4ST+18A (FN=86). In each karyotype, the nucleolus organizer regions were detected at the end of the short arm of a single medium-sized subtelocentric chromosome. The Chromomycin A3 (CMA3) marking is coincident for the NORs in chromosomes of the two species and present additionally in two different chromosomes of A. altiparanae thus showing interpopulation differences in this species. In H. eques, weak heterochromatic blocks in the position of centromeres and telomeres of most chromosomes and negative C-banding for the NOR bearing chromosome were visualized. The obtained results contribute both to the understanding of karyotype evolution of these species and to the clarifying their phylogenetic relationships.

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Research Article Tue, 14 Feb 2012 00:00:00 +0200
Three sympatric karyomorphs in the fish Astyanax fasciatus (Teleostei, Characidae) do not seem to hybridize in natural populations https://compcytogen.pensoft.net/article/1746/ Comparative Cytogenetics 6(1): 29-40

DOI: 10.3897/compcytogen.v6i1.2151

Authors: Maressa Ferreira-Neto, Roberto Artoni, Marcelo Vicari, Orlando Moreira Filho, Juan Camacho, Mohammed Bakkali, Claudio Oliveira, Fausto Foresti

Abstract: Ninety individuals of the characid fish Astyanax fasciatus (Cuvier, 1819) were collected at Água da Madalena stream (Botucatu, São Paulo, Brazil) and analyzed for diploid chromosome number 2n and karyotype composition as well as for the chromosomal location of the 5S and 18S ribosomal DNA (rDNA). Whereas no chromosome differences were associated with sex, three different karyomorphs with diploid chromosome numbers 2n=46, 2n=48 and 2n=50 were found. No intermediate 2n numbers were discovered. The 2n=50 karyomorph showed some differences in 18S rDNA location compared to the two other karyomorphs. Finally, all specimens with the 2n=46 karyomorph showed the presence of a partly heterochromatic macro supernumerary chromosome, which was absent in all individuals with the two other karyomorphs. All these results suggest that indviduals of the three different karyomorphs are not likely to hybridize in the examined populations. Our findings strongly suggest the presence of three separate species (sensu biological species concept) easily diagnosed on the basis of differences in the diploid chromosome numbers and other chromosomal markers.

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Research Article Tue, 24 Jan 2012 00:00:00 +0200
Cytotaxonomy of the subgenus Artibeus (Phyllostomidae, Chiroptera) by characterization of species-specific markers https://compcytogen.pensoft.net/article/1747/ Comparative Cytogenetics 6(1): 17-28

DOI: 10.3897/compcytogen.v6i1.1510

Authors: Marcela de Lemos Pinto, Merilane da Silva Calixto, Maria José de Souza, Ana Paloma Tavares de Araújo, Alfredo Langguth, Neide Santos

Abstract: The genus Artibeus represents a highly diverse group of bats from the Neotropical region, with four large species occurring in Brazil. In this paper, a comparative cytogenetic study was carried out on the species Artibeus obscurus Schinz, 1821, A. fimbriatus Gray, 1838, A. lituratus Olfers, 1818 and A. planirostris Spix, 1823 that live sympatrically in the northeast of Brazil, through C-banding, silver staining and DNA-specific fluorochromes (CMA3 and DAPI). All the species had karyotypes with 2n=30,XX and 2n=31,XY1Y2, and FN=56. C-banding showed constitutive heterochromatin (CH) blocks in the pericentromeric regions of all the chromosomes and small CH blocks at the terminal region of pairs 5, 6, and 7 for all species. Notably, our C-banding data revealed species-specific autosomic CH blocks for each taxon, as well as different heterochromatic constitution of Y2 chromosomes of A. planirostris. Ag-NORs were observed in the short arms of chromosomes 5, 6 and 7 in all species. The sequential staining AgNO3/CMA3/DA/DAPI indicated a positive association of CH with Ag-NORs and positive CMA3 signals, thus reflecting GC-richness in these regions in A. obscurus and A. fimbriatus. In this work it was possible to identify interespecific divergences in the Brazilian large Artibeus species using C-banding it was possible provided a suitable tool in the cytotaxonomic differentiation of this genus.

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Research Article Tue, 24 Jan 2012 00:00:00 +0200
First record of supernumerary (B) chromosomes in electric fish (Gymnotiformes) and the karyotype structure of three species of the same order from the upper Paraná River basin https://compcytogen.pensoft.net/article/1748/ Comparative Cytogenetics 6(1): 1-16

DOI: 10.3897/compcytogen.v6i1.1752

Authors: Valéria Mendes, Ana Luiza Portela-Castro, Horácio Júlio-Júnior

Abstract: Cytogenetic studies were performed on the species Apteronotus prope albifrons Linnaeus, 1766, Rhamphichthys hahni Meinken, 1937 and Brachyhypopomus gauderio Giora & Malabarba, 2009, collected in the upper Paraná River floodplain, Porto Rico (PR), Brazil. Apteronotus prope albifrons showed a diploid number of 2n=24 chromosomes for both sexes and a karyotype formula of 14m+2sm+2st+6a (FN=42). Besides the standard karyotype, three specimens had one to three extra microchromosomes with inter- and intra-individual variations, which suggested the occurrence of B chromosomes in the species. The chromosomal data of R. hahni, described here for the first time, consists of 50 chromosomes and a formula comprised of 20m+24sm+6a (FN=94). Brachyhypopomus gauderio specimens demonstrated 2n=42 chromosomes in females, all acrocentric, and 2n=41 chromosomes in males, with 40 acrocentric and 1 medium-sized metacentric chromosome. These differences concern with a multiple system of sex chromosome determination X1X1X2X2/X1X2Y (FN=42) in B. gauderio. The analysis of nucleolar organizer regions by Ag-NOR and FISH 18S banding revealed a simple NOR system in A. prope albifrons and R. hahni and a multiple NOR system in B. gauderio, that is unusual for Gymnotiformes fishes. Constitutive heterochromatin was mainly found in the pericentromere region in most of the chromosomes of the three species, although each species had its own peculiarities. The B chromosomes in Apteronotus prope albifrons demonstrated heterochromatin positioned in the centromeric and telomeric regions whereas R. hahni presented conspicuous blocks of heterochromatin on the long arms in three submetacentric pairs. Brachyhypopomus gauderio showed blocks of heterochromatin on the long arm in the interstitial and telomere positions. The finding of B chromosomes in A. prope albifrons represents the first description of these elements in the Gymnotiformes order. Although the karyotype of this species is similar with that described for populations in the Amazon basin, the presence of B chromosomes could represent a specific characteristic of this population. A comparative analysis of karyotypes of R. hahni with other species of the genus showed a relatively conservative structure suggesting 2n=50 as a common number in this group. The karyotype of B. gauderio, a new species, provides an important reference for future chromosome studies of the Brachyhypopmus Mago-Lecia, 1994, and it might be also significant for cytotaxonomy in this group. The cytogenetic data also demonstrate the need of more comparative cytogenetic studies in the families of the highly diversified and taxonomically difficult complex Gymnotiformes.

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Research Article Tue, 24 Jan 2012 00:00:00 +0200
Comparative cytogenetics of two of the smallest Amazonian fishes: Fluviphylax simplex Costa, 1996 and Fluviphylax zonatus Costa, 1996 (Cyprinodontiformes, Poeciliidae) https://compcytogen.pensoft.net/article/1738/ Comparative Cytogenetics 5(5): 411-422

DOI: 10.3897/compcytogen.v5i5.1562

Authors: Eduardo Souza, Leila Ribeiro, E Feldberg, Izeni Farias, Tomas Hrbek, Maria Gross

Abstract: The genus Fluviphylax Whitley, 1965 is comprized of five valid species (F. pygmaeus Myers et Carvalho, 1955, F. zonatus, F. simplex, F. obscurus Costa, 1996, and F. palikur Costa et Le Bail, 1999), which are endemic to the Amazon region. These fishes are the smallest known South American vertebrates and among the smallest know vertebrates on Earth. All species but the type F. pygmaeus have been described in late 1990’s, and much remains unknown about the biology, taxonomy and systematics of this group of fishes. The aims of the present study were to establish the diploid and haploid number of F. zonatus and F. simplex, and to find species-specific markers for the discrimination of taxa. The diploid number for both species was 48 chromosomes, with no sex chromosome heteromorphism. Fluviphylax zonatus exhibited the karyotypic formula 4m+8sm+22st+14a and FN=82, and F. simplex exhibited 4m+16sm+18st+10a and FN=86. The determination of the total mean length of the chromosomes and their grouping into five size classes demonstrated different chromosome composition of the two species. This difference was further supported by the distribution of constitutive heterochromatin. The meiotic analysis revealed 24 bivalents in both species, but F. zonatus exhibited chromosomes with late pairing of the telomeric portions in the pachytene. These data reveal that cytogenetic characterization is useful and important for the discrimination of these species. Our study further indicates that this method could be employed in the analysis of other species of small fishes that are difficult to distinguish using traditional morphological traits or are morphologically cryptic.

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Research Article Thu, 22 Dec 2011 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 diversification in ribosomal DNA sites in Ancistrus Kner, 1854 (Loricariidae, Ancistrini) from three hydrographic basins of Mato Grosso, Brazil https://compcytogen.pensoft.net/article/1733/ Comparative Cytogenetics 5(4): 289-300

DOI: 10.3897/compcytogen.v5i4.1757

Authors: Sandra Mariotto, Liano Centofante, Marcelo Vicari, Roberto Artoni, Orlando Moreira Filho

Abstract: Populations of seven Ancistrus species were analyzed from streams and rivers of three hydrographic Brazilian basins. All populations showed different diploid numbers (2n), fundamental numbers (FNs), and karyotypes. Some representatives of Loricariidae have 2n = 54 chromosomes, which is very likely an ancestral cytotaxonomic characteristic, but many other representatives show extensive karyotype diversification. In the Ancistrus species studied, extensive karyotypic differentiation, which is generally associated with chromosome number reduction and rearrangement of the ribosomal RNA gene (rDNA) sites, was verified. Chromosomal locations of 18S and 5S rDNA were jointly detected using fluorescence in situ hybridization (FISH). In all the Ancistrus species analyzed, 18S rDNA sites were detected only on one chromosome pair, though this differed among species. 5S rDNA was located on 1–3 chromosome pairs either separately or in synteny with 18S rDNA in four of the seven species/populations. Hence the karyotype differentiation in Ancistrus species could be associated with a morphological speciation process, suggesting that chromosome fusions, inversions, deletions, duplications, and heterochromatination could contribute to the karyotype evolution of these neotropical armored catfishes.

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Research Article Wed, 9 Nov 2011 00:00:00 +0200
Description of karyotype in Hypostomus regani (Ihering, 1905) (Teleostei, Loricariidae) from the Piumhi river in Brazil with comments on karyotype variation found in Hypostomus https://compcytogen.pensoft.net/article/1714/ Comparative Cytogenetics 5(2): 133-142

DOI: 10.3897/compcytogen.v5i2.964

Authors: Ernani de Oliveira Mendes-Neto, Marcelo Ricardo Vicari, Roberto Artoni, Orlando Moreira-Filho

Abstract: The paper represents a comparative cytogenetic analysis of three populations of Hypostomus regani in Brazil. Two populations belong to the Upper Paraná River Basin and the third one, the karyotype of which is described for the first time, was probably introduced into the São Francisco River Basin through transposition from the Piumhi River. Karyotype features of populations of H. regani from the Piracicaba and Tietê River Basins are also discussed. The occurrence of H. regani in the São Francisco River Basin is reported for the first time here. The study also revealed distinct differences in the location of the Ag-NORs between the analyzed populations that enable individuals from the Piumhi River, Mogi-Guaçu River and Tietê River to be distinguished from one another. Thus, the data obtained indicate the possibility of geographic variation fixing different karyotypes even in the same basin of origin.

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Research Article Fri, 1 Jul 2011 00:00:00 +0300
Chromosomal location of heterochromatin and 45S rDNA sites in four South American triatomines (Heteroptera: Reduviidae) https://compcytogen.pensoft.net/article/1702/ Comparative Cytogenetics 4(2): 141-149

DOI: 10.3897/compcytogen.v4i2.50

Authors: Vanessa Bardella, M Gaeta, A Vanzela, M Azeredo-Oliveira

Abstract: The Triatominae are distributed in Brazilian regions and are the vector of Chagas disease. This group is also characterized by lower karyotype variability, occurrence of holokinetic chromosomes and inverted meiosis of the sex chromosomes. In this study, we determined the karyotype of four species of the genus Triatoma Laporte, 1832 using chromosome measurement, chromosome banding and FISH with a 45S rDNA probe. All samples showed 2n = 20A+XY with chromosomes sorted by size in decreasing order. Heterochromatin of Triatoma infestans melanosoma Lent, Jurberg, Galvão, Carcavallo, 1994 is distributed among eight autosomes and the sex chromosomes. In Triatoma brasiliensis Neiva, 1911, T. matogrossensis Leite, Barbosa, 1953 and T. rubrovaria Blanchard, 1834, heterochromatin was restricted to the Y chromosome, which was characterized as DAPI+ (weak signal). FISH using a 45S rDNA probe of Drosophila melanogaster Meigen, 1830 showed differences in the number and location of hybridization sites. T. brasiliensis and T. rubrovaria showed the signal on one autosome pair. T. matogrossensis showed signals on both sex chromosomes, and T. infestans melanosoma only on the X chromosome. Conventional banding analysis suggests a closer relationship between T. brasiliensis, T. matogrossensis and T. rubrovaria, except with regard to 45S rDNA location in T. matogrossensis, and a more differentiated karyotype in T. infestans melanosoma.

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Research Article Thu, 30 Dec 2010 00:00:00 +0200
Different cytotypes in fishes of the genus Hypostomus Lcépède, 1803, (Siluriformes: Loricariidae) from Xingu river (Amazon region, Brazil) https://compcytogen.pensoft.net/article/1692/ Comparative Cytogenetics 4(1): 45-54

DOI: 10.3897/compcytogen.v4i1.31

Authors: Susana Milhomem, Roberta Castro, C Nagamachi, A De Souza, E Feldberg, Julio Pieczarka

Abstract: We analyzed the karyotypes of three specimens of fishes of the genus Hypostomus Lacepede, 1803 (Loricaridae) from Xingu River (Amazon region). We used conventional staining techniques, including C-banding, Ag-NOR staining, CMA3- and DAPI-banding. Each specimen had a different cytotype: Hypostomus sp. Xingu-1 had 2n=64 (32M/SM, 32ST/A); Hypostomus sp. Xingu-2 has 2n=66 (32M/SM, 34ST/A), and Hypostomus sp. Xingu-3 had 2n=65 (38M/SM, 26ST/A + 1 B). The three cytotypes showed similar C-, CMA3- and DAPI-banding patterns. The nucleolus organizing regions were located in the short arm of chromosome pair 25 of Hypostomus sp. Xingu-1 and pair 29 of Hypostomus sp. Xingu-2, and in the long arm of pair 30 of Hypostomus sp. Xingu-3, probably because of a pericentric inversion. A fusion/fission rearrangement explains the difference in the diploid number and number of M/SM and ST/A chromosomes between the 2n= 64 and 2n=66 cytotypes. The B chromosome most probably explains the difference between the 2n=64 and 2n=65 cytotypes. The cytotype with 2n=65 had a significantly larger number of M/SM chromosomes, probably because of pericentric inversions. These three cytotypes may represent different species.

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Research Article Fri, 9 Jul 2010 00:00:00 +0300
Cytogenetic analysis in catfish species of the genus Peckoltia Miranda Ribeiro, 1912 (Teleostei: Siluriformes: Loricariidae) https://compcytogen.pensoft.net/article/1684/ Comparative Cytogenetics 3(2): 103-109

DOI: 10.3897/compcytogen.v3i2.17

Authors: A De Souza, C Nagamachi, Susana Milhomem, E Feldberg, J Pieczarka

Abstract: This study describes the karyotypes of three species of the genus Peckoltia (Loricariidae: Ancistrini). Fishes were collected in the Jari (Peckoltia sp. 1 and Peckoltia sp. 2) and Xingu rivers (Peckoltia vittata (Steindachner, 1881)) in the Amazon rainforest. Karyotypes were 2n = 52 for Peckoltia vittata (FN=102: 16 metacentrics (m), 20 submetacentrics (sm), 14 subtelocentrics (st), 2 acrocentrics (a)) and Peckoltia sp. 2 (FN=102: 32 m + sm, 18st, 2a). Peckoltia sp. 1 (FN=102: 44 m + sm, 6st, 2a, 1B) had 2n = 53 due to a B chromosome. The species differ in chromosomal morphology. Nucleolar Organizer Regions (NOR) was identified within a distal region of the long arm of pair 9 in Peckoltia vittata, in pair 10 and in a homologue of pair 25 in Peckoltia sp. 1, as well as in pair 17 and in a homologue of pair 18 in Peckoltia sp. 2. Chromomycin A3 banding agreed with the location of the NORs. C-banding patterns revealed large non-centromeric heterochromatic blocks, probably of a common origin. Our results suggest a higher level of similarity between Peckoltia vittata and Peckoltia sp. 1.

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Research Article Tue, 29 Dec 2009 00:00:00 +0200
Hsc-FA and NOR bandings on chromosomes of the giant ant Dinoponera lucida Emery, 1901 (Hymenoptera: Formicidae) https://compcytogen.pensoft.net/article/1683/ Comparative Cytogenetics 3(2): 97-102

DOI: 10.3897/compcytogen.v3i2.16

Authors: Luísa Barros, C Mariano, S Pompolo, Jacques Delabie

Abstract: The distribution of the threatened ant Dinoponera lucida is limited to the south of the State of Bahia, farthest east of Minas Gerais and north of Espirito Santo, Brazil. Recent cytogenetic studies carried out in 15 sites distributed along the range of the ant indicated high chromosome number variation in the populations of Bahia, 2n=106 to 120 chromosomes, while the populations of Espirito Santo presented a constant number, with 2n=118 chromosomes. This study aimed at describing the banding pattern of D. lucida chromosomes, in some populations of Espirito Santo and Bahia, applying the Hsc-FA technique (secondary constriction heterochromatin-associated bands by fluorescence using acridine) and identifying the nucleolar organizing region (active NORs) impregnated with AgNO 3 which is especially important for the cytogenetic characterization of a species. The utilization of these two techniques showed positive interstitial markings on the region of the long arm of the pair AMt, similar to those obtained with the CMA 3 fluorochrome and with the FISH technique complementing the cytogenetic data of this species.

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Research Article Tue, 29 Dec 2009 00:00:00 +0200