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Made available in DSpace on 2020-12-12T01:13:54Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-02-01 Cytogenetic data showed a variation in diploid chromosome number in the genus Hyphessobrycon ranging from 2n = 46 to 52, and studies involving repetitive DNA sequences are scarce in representatives of this genus. The purpose of this paper was the chromosomal mapping of repetitive sequences (rDNA, histone genes, U snDNA and microsatellites) and investigation of the amplification of 5S rDNA clusters in the Hyphessobrycon eques genome. Two H. eques populations displayed 2n = 52 chromosomes, with the acrocentric pair No. 24 bearing Ag-NORs corresponding with CMA3+/DAPI−. FISH with a 18S rDNA probe identified the NORs on the short (p) arms of the acrocentric pairs Nos. 22 and 24. The 5S rDNA probe visualized signals on almost all chromosomes in genomes of individuals from both populations (40 signals); FISH with H3 histone probe identified two chromosome pairs, with the pericentromeric location of signals; FISH with a U2 snDNA probe identified one chromosome pair bearing signals, on the interstitial chromosomal region. The mononucleotide (A), dinucleotide (CA) and tetranucleotide (GATA) repeats were observed on the centromeric/pericentromeric and/or terminal positions of all chromosomes, while the trinucleotide (CAG) repeat showed signals on few chromosomes. Molecular analysis of 5S rDNA and non-transcribed spacers (NTS) showed microsatellites (GATA and A repeats) and a fragment of retrotransposon (SINE3/5S-Sauria) inside the sequences. This study expanded the available cytogenetic data for H. eques and demonstrated to the dispersion of the 5S rDNA sequences on almost all chromosomes. Centro de Ciências Biológicas e da Saúde Laboratório de Citogenética Universidade Estadual do Oeste do Paraná (UNIOESTE), Rua Universitária, 2069 Universidade Estadual de Mato Grosso do Sul (UEMS) Unidade de Mundo Novo, BR 163, Km 20.2 Instituto de Biociências Departamento de Biologia Laboratório de Citogenética Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP), Av. 24A, 1515 Instituto de Biociências Departamento de Biologia Laboratório de Citogenética Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP), Av. 24A, 1515

Gymnotiformes fishes present a great variation in chromosome numbers. Sternopygidae species are either sex-homomorphic or sex-heteromorphic. This study reports a novel ZZ/ZW chromosome morphology type in Eigenmannia virescens collected from the upper Parana River basin, which presented karyotype composed of 2n = 38 chromosomes, 6 metacentric (m), 10 submetacentric (sm), 4 subtelocentric (st) and 18 acrocentric (a) for males and 5 m, 11 sm, 4 st and 18 a for females, where the Z is a metacentric chromosome and the W is submetacentric chromosome. A single pair of chromosomes carrying the nucleolar organizing regions (NORs) was detected in the acrocentric chromosome pair No. 15 by silver-staining and confirmed by the 18S rDNA-FISH. Multiple 5S rDNA sites were detected in the karyotype, all of them in pericentromeric regions. The heterochromatin was mainly located in the pericentromeric regions of all chromosomes, and a conspicuous accumulation of heterochromatin colocated in NORs sites. Thus, the variation of Z and W chromosome types, associated with different chromosome sex systems (undifferentiated, XX/XY and ZZ/ZW) and different karyotypic formulae, reinforce that E. virescens should be considered a species complex.

Made available in DSpace on 2018-11-26T17:44:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-12-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) The Piabina genus was allocated in Stervadiinae subfamily after staying for years as an uncertain group in Characidae. Few cytogenetic studies are described in the literature for Piabina argentea, thus new analyzes in other populations are important to understanding of the chromosomal dynamics of them. The aim of this paper was to analyze the chromosomes of P. argentea from Corumbatai River basin focusing mainly the chromosomal locations of 18S rDNA and 5S rDNA clusters. The diploid chromosome number was 2n = 52 for P. argentea, which were classified as 6 metacentrics (m), 8 submetacentrics (sm), 24 subtelocentrics (st) and 14 acrocentrics (a), and FN (fundamental number) value 90 in both sexes. Silver nitrate impregnation located the nucleolus organizer regions (Ag-NORs) on the short (p) arm of pair 16, however, an intra-individual variation of Ag-NORs sites was observed in two individuals. Fluorescence in situ hybridization (FISH) revealed six 18S rDNA sites (pairs 8, 10 and 16) and four 5S rDNA sites in terminal positions of the short arm of pairs 5 and 22 (one submetacentric and one acrocentric) in P. argentea. The results indicate that, despite the conserved diploid number, this group of fish presents a wide variability of the 18S and 5S rDNA sites. Univ Estadual Paulista, UNESP, Inst Biociencias, Dept Biol,Lab Citogenet, Av 24A,1515, BR-13506900 Rio Claro, SP, Brazil Univ Estadual Mato Grosso do Sul UEMS, Unidade Mundo Novo, BR 163,Km 20-2, BR-79980000 Mundo Novo, MS, Brazil Univ Estadual Paulista, UNESP, Inst Biociencias, Dept Biol,Lab Citogenet, Av 24A,1515, BR-13506900 Rio Claro, SP, Brazil

Made available in DSpace on 2018-12-11T16:47:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-01-01 Repetitive sequences and their chromosomal locations have been widely studied in species of the Astyanax genus. However, the chromosomal organization of U2 snDNA remains largely unknown. The aims of this study were to examine the chromosomal contexts of U2 snRNA and 5S rRNA genes in Astyanax species and determine the degree of chromosome morphological similarity between species with different diploid numbers. Clusters of U2 snDNA and 5S rDNA were determined in nine species of Astyanax, including two karyomorphs of Astyanax fasciatus Cuvier, 1819. All species exhibited U2 snDNA clusters on two chromosome pairs, except Astyanax mexicanus De Filippi, 1853 (one pair). The 5S rDNA clusters were located on one chromosome pair in Astyanax altiparanae Garutti and Britski, 2000, and Astyanax marionae Eigenmann, 1911, two pairs in Astyanax abramis Jenyns, 1842, Astyanax asuncionensis Géry, 1972, Astyanax bockmanni Vari and Castro, 2007, Astyanax eigenmanniorum Cope, 1894, A. fasciatus (karyomorphs I and II), and Astyanax schubarti Britski, 1964, and four pairs in A. mexicanus. The relationships between the repetitive sequences in different species suggest that A. schubarti and A. mexicanus exhibit an unusual U2 snDNA chromosomal format as a result of events occurring in the evolutionary history of the Astyanax group. Laboratório de Citogenética Departamento de Biologia Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Av. 24A, 1515 Laboratório de Genética Animal Departamento de Biologia e Zoologia, Universidade Federal de Mato Grosso (UFMT) Laboratório de Citogenética Departamento de Biologia Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Av. 24A, 1515

Made available in DSpace on 2018-12-11T16:41:24Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-01-17 The genus Astyanax is widely distributed from the southern United States to northern Patagonia, Argentina. While cytogenetic studies have been performed for this genus, little is known about the histone gene families. The aim of this study was to examine the chromosomal relationships among the different species of Astyanax. The chromosomal locations of the 5S rRNA and H3 histone genes were determined in A. abramis, A. asuncionensis, A. altiparanae, A. bockmanni, A. eigenmanniorum, A. mexicanus (all 2n = 50), A. fasciatus (2n = 46), and A. schubarti (2n = 36). All eight species exhibited H3 histone clusters on two chromosome pairs. In six species (A. abramis, A. asuncionensis, A. altiparanae, A. bockmanni, A. eigenmanniorum, and A. fasciatus), syntenic clusters of H3 histone and 5S rDNA were observed on metacentric (m) or submetacentric (sm) chromosomes. In seven species, clusters of 5S rDNA sequences were located on one or two chromosome pairs. In A. mexicanus, 5S rDNA clusters were located on four chromosome pairs. This study demonstrates that H3 histone clusters are conserved on two chromosome pairs in the genus Astyanax, and specific chromosomal features may contribute to the genomic organization of the H3 histone and 5S rRNA genes. Instituto de Biociências Departamento de Biologia Laboratório de Citogenética Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Av. 24A, 1515 Instituto de Biociências Departamento de Biologia Laboratório de Citogenética Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Av. 24A, 1515

The organization of microsatellites in B and sex chromosomes has been linked to chromosomal evolution in a number of animal groups. Here, the chromosomal organizations of (CA)15, (GA)15, (CG)15, (GACA)4, and (GATA)8 microsatellites were examined in several Astyanax species with different diploid numbers: Astyanax mexicanus (2n = 50 + 1 B chromosome), A. altiparanae (2n = 50), A. marionae (2n = 48), A. fasciatus (2n = 46), and A. schubarti (2n = 36). The (CA)15 and (GA)15 microsatellites were dispersed across the chromosomes of A. altiparanae and A. fasciatus but were also observed as clusters (CA and GA for A. altiparanae, and CA for A. fasciatus). In A. marionae and A. schubarti, the (CA)15 and (GA)15 microsatellites were dispersed but were also observed as clustered signals and coincident with heterochromatic regions. In all 4 of these species, the (CG)15 and (GACA)4 microsatellites were dispersed across chromosomes, and the (GATA)8 microsatellite was co-localized with 5S rDNA. In A. mexicanus, the (CA)15, (GA)15, (CG)15, (GATA)8, and (GACA)4 microsatellites were weakly detected and dispersed across the chromosomes of the A complement. On the B chromosome, signals for the different microsatellites were weak, strong, absent, weak, and absent, respectively. The distribution of microsatellites and the locational relationship between microsatellites and 5S rDNA are discussed, and a possible evolutionary pathway is proposed for microsatellites in Astyanax.

Made available in DSpace on 2018-12-11T16:52:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-03-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) The U small nuclear RNA (U snRNA) genes comprise a multigene family and are required for splicing of pre-mRNA. In this paper, we aimed to study the chromosomal location of the U2 snRNA gene in Megaleporinus, Leporinus and Schizodon species, which constitute interesting models for the study of repetitive DNA and genomic evolution in fish once the group comprises species with and without heteromorphic sex chromosomes. The all six species showed 2n = 54 chromosomes: Megaleporinus elongatus, Megaleporinus macrocephalus, Leporinus striatus, Leporinus friderici, Schizodon borelli and Schizodon isognathus. The U2 snDNA clusters were evident in only one medium-sized submetracentric pair in all analyzed species and this may represent a condition shared by Anostomidae family. Instituto de Biociências Departamento de Biologia Laboratório de Citogenética Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP), Av. 24A, 1515 Instituto de Biociências Departamento de Biologia Laboratório de Citogenética Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP), Av. 24A, 1515 FAPESP: 10/10/51339-0

Made available in DSpace on 2018-12-11T16:51:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-01-02 The cytogenetic studies of retrotranposons Rex have been characterized in several fish groups, including species of the Astyanax genus. This group presents an extensive variability in their karyotype, with diploid numbers of 2n = 52, 50, 48, 46 and 36 chromosomes. Thus, the aim of this study was to evaluate the distribution of the retrotransposable element Rex1, in six Astyanax species, with different diploid numbers. The species analyzed were Astyanax altiparanae (2n = 50), Astyanax asuncionensis (2n = 50), Astyanax eigenmanniorum (2n = 50), Astyanax marionae (2n = 48), Astyanax fasciatus (2n = 46) and Astyanax schubarti (2n = 36). Rex1 was dispersed in the Astyanax species, suggesting that these retrotransposons play important role in genome evolution. Instituto de Biociências Departamento de Biologia Laboratório de Citogenética Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP) Instituto de Biociências Departamento de Biologia e Zoologia Laboratório de Genética Animal Universidade Federal de Mato Grosso (UFMT) Instituto Federal de Educação Ciência e Tecnologia do Piauí (IFPI) Laboratório de Biologia Instituto de Biociências Departamento de Biologia Laboratório de Citogenética Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP)

The genus Piabucus is the only member of the subfamily Iguanodectinae found in the Pantanal of Mato Grosso State, where it is represented by Piabucus melanostomus. P. melanostomus from the Paraguay and Bento Gomes Rivers of the Pantanal wetlands were analysed using conventional and molecular cytogenetic techniques to cytogenetically characterise the species and broaden the knowledge of the subfamily. The results indicated no sex-related heteromorphisms. The diploid number for the species was 2n = 50 chromosomes, which were divided into six metacentric, eight submetacentric, 24 subtelocentric, and 12 acrocentric with a fundamental number (FN) of 88. Heterochromatin was visualised using the C-banding technique, which showed that it was mainly distributed in the centromeric and pericentromeric region of most chromosomes, but larger blocks were observed on the long arms of large subtelocentric chromosomes (8, 9, 10, 13, and 20 pairs). Nucleolar organising regions (Ag-NOR) were observed in the p-subterminal region of one subtelocentric chromosome pair (9) with a remarkable size polymorphism between homologues in individuals from the Paraguay River, which was confirmed using the FISH technique with 18S rDNA. In this population, in all individuals studied, one of the homologous shows block considerably larger. The karyotype was compared with those of other subfamilies considered basal in Characidae, according to morphological data.

Characidae is one of the predominant fish groups in the Neotropical region with approximately 30 highly diversified subfamilies, probably not representing a monophyletic group. Three Characidae species from the Iguatemi River Basin (Mundo Novo, MS, Brazil) were analyzed: Astyanax bockmanni with 2n=50 chromosomes (6m+20sm+8st+16a), Bryconamericus stramineus with 2n=52 chromosomes (6m+10sm+16st+20a) and Piabina argentea with 2n=52 chromosomes (6m+24sm+12st+10a), all the species showing no differences between male and female karyotypes. The Ag-NORs were located in only a single chromosome pair in the three species. The chromosomal data obtained may be useful for the taxonomy and phylogenetic studies in these fish groups.

Made available in DSpace on 2014-12-03T13:11:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-04-01Bitstream added on 2014-12-03T13:22:50Z : No. of bitstreams: 1 WOS000317829800001.pdf: 597255 bytes, checksum: d596e504ddd65c823178cb74e22b9092 (MD5) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Background: Nowadays, the genus Bryconamericus is placed in subfamily Stevardiinae within of Characidae, but not shows consistent evidence of monophyletism. The purpose of this work was to study the chromosomes of three species of Bryconamericus, aiming to add cytogenetic knowledge and contribute to the understanding of the chromosomal evolution of this genus.Results: The chromosomes of three species of Bryconamericus were analyzed using cytogenetic techniques. The karyotype of Bryconamericus stramineus contained 6 metacentric (m) + 10 submetacentric (sm) + 16 subtelocentric (st) + 20 acrocentric (a), the fundamental number (FN) of 84, one silver impregnated (Ag-NOR) pair, one pair bearing the 18S ribosomal DNA sites, another pair bearing the 5S rDNA sites, and a few positive C-bands. Bryconamericus turiuba had a karyotype containing 8 m + 10sm + 14st + 20a (FN = 84), one chromosome pair Ag-NOR, two pairs bearing the 18S rDNA sites, two pairs bearing the 5S rDNA sites, and a few C-band regions. Bryconamericus cf. iheringii had a karyotype containing 10 m + 14sm + 18st + 10a (FN = 94), including one pair with a secondary constriction Ag-NOR positive. In this karyotype the fluorescent in situ hybridization (FISH) showed the 18S and 5S rDNA probe in adjacent position.Conclusions: The results obtained in this work showed different characteristics in the organization of two multigene families, indicating that distinct evolutionary forces acting on the diversity of rDNA sequences in the genome of three Bryconamericus species. Univ Estadual Paulista Julio Mesquita Filho UNESP, Inst Biociencias, Dept Biol, Lab Citogenet, BR-13506900 Rio Claro, SP, Brazil Univ Estadual Mato Grosso Sul UEMS, BR-79980000 Mundo Novo, MS, Brazil Univ Estadual Paulista Julio Mesquita Filho UNESP, Inst Biociencias, Dept Biol, Lab Citogenet, BR-13506900 Rio Claro, SP, Brazil