28 research outputs found

    Cytogenetic Markers Reinforce the Redescription of the Armored Pleco Hypostomus spiniger (Loricariidae - Hypostominae), an Endemic Species in the Uruguay River Basin and Patos Lagoon System

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    Among the Neotropical fish fauna, suckermouth armored catfishes (Hypostomus - Loricariidae) stands out as one of the most difficult groups to diagnose morphologically. So the use of different molecular markers, as is the case of cytogenetics, has been fundamental for a precise identification of some species. In the present study, we characterize the karyotypes of two allopatric Hypostomus spiniger populations, using classical and molecular cytogenetic methods. This species was described by Hensel (1870) but later synonymized with Hypostomus commersoni, and recently it was again recognized as a valid species. Taking to account this taxonomic problematic, the aim of this study is to determine chromosomal characters that may be useful to validate the taxonomic status of H. spiniger and to complement its diagnosis in relation to H. commersoni populations. The karyotype of H. spiniger is composed by 66 chromosomes (10m+16sm+14st+26a), few heterochromatin and a multiple nucleolar organizer regions (NORs) system. Despite, the currently geographic isolation among the samples collected in Forquetinha River (Patos Lagoon basin) and Quadros Lagoon (Tramandaí River basin), both shared the same karyotypic structure, this cytogenetic evidence, suggest that both populations belongs to the same species. Additionally, our results clearly distinguish H. spiniger from H. commersoni populations collected along the Paranå River basin, that exhibited 2n=68 chromosomes and several divergences in heterochromatin and NORs pattern. In sum, the present study reinforces the valid status of H. spiniger and demonstrated the importance of basic cytogenetic analysis to understand conflictuous taxonomic matters.Fil: Takagui, Fabio Hiroshi. Universidade Estadual de Londrina. Departamento de Biología General; BrasilFil: Rubert, Marceléia. Universidade Estadual de Londrina. Departamento de Biología General; BrasilFil: Dionisio, Jaqueline Fernanda. Universidade Estadual de Londrina. Departamento de Biología General; BrasilFil: BaumgÀrtner, Lucas. Universidade Estadual Do Oeste Do Parå; BrasilFil: Cardoso, Yamila Paula. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Laboratorio de Sistemåtica y Biología Evolutiva; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Jerep, Fernando Camargo. Universidade Estadual de Londrina. Departamento de Biología General; BrasilFil: Giuliano Caetano, Lucia. Universidade Estadual de Londrina; Brasi

    Cytogenetic study of two species of the family Pimelodidae (Siluriformes) collected in Lago GuaĂ­ba, Rio Grande do Sul, Brazil

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    Exemplares de Parapimelodus nigribarbis e Pimelodus maculatus coletados na bacia do rio GuaĂ­ba, Porto Alegre, Rio Grande do Sul, foram analisados citogeneticamente. As duas espĂ©cies apresentaram um nĂșmero diplĂłide de 56 cromossomos, com P. nigribarbis mostrando um cariĂłtipo de 20m + 20sm + 4st + 12a, NF igual a 100; e P. maculatus com 24m + 20sm + 6st + 6a e NF igual 106. As NORs foram evidenciadas em apenas um par de cromossomos subtelocĂȘntricos, na regiĂŁo terminal do braço longo, nas duas espĂ©cies estudadas, sendo coincidentes com a banda C e CMA3; o DAPI nestas regiĂ”es se mostrou negativo. Parapimelodus nigribarbis apresentou um maior nĂșmero de bandas heterocromĂĄticas do que P. maculatus, distribuĂ­das principalmente em regiĂ”es terminais, sendo observada nesta Ășltima espĂ©cie uma banda intersticial no braço curto do primeiro par metacĂȘntrico. Banda C + CMA3 evidenciou em P. nigribarbis e P. maculatus a heterocromatina associada Ă  NOR rica em GC, sendo encontrada na primeira espĂ©cie outras regiĂ”es fluorescentes. Com banda C + DAPI vĂĄrias regiĂ”es cromossĂŽmicas foram observadas nas duas espĂ©cies, inclusive a porção intersticial encontrada em P. maculatus, revelando que a heterocromatina possui uma maior quantidade de regiĂ”es AT ricas em sua composição.A cytogenetic study was conducted on specimens of Parapimelodus nigribarbis and Pimelodus maculatus collected in the lago GuaĂ­ba drainage, Porto Alegre, Rio Grande do Sul, Brazil. The two species had a diploid number of 56 chromosomes, with P. nigribarbis showing a karyotype of 20m + 20sm + 4st + 12a with FN of 100, and P. maculatus showing a karyotype of 24m + 20sm + 6st + 6a with FN of 106. NORs were demonstrated in both species in only one pair of subtelocentric chromosomes, in the terminal region of the long arm, which was coincident with C- banding and CMA3 staining, while DAPI staining was negative in these regions. Parapimelodus nigribarbis had a greater number of heterochromatic bands than did P. maculatus, which were distributed mainly in the terminal regions, where the latter species showed an interstitial band on the short arm of the first metacentric pair. C-banding plus CMA3 demonstrated heterochromatin that was associated with GC-rich NORs in both P. nigribarbis and P. maculatus, although other fluorescent regions were also observed in the former species. With C-banding plus DAPI, various chromosomal regions were stained in the two species, along with interstitial staining in P. maculatus, indicating that heterochromatin contained a greater quantity of AT-rich regions

    Cytogenetic study of two species of the family Pimelodidae (Siluriformes) collected in Lago GuaĂ­ba, Rio Grande do Sul, Brazil

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    Exemplares de Parapimelodus nigribarbis e Pimelodus maculatus coletados na bacia do rio GuaĂ­ba, Porto Alegre, Rio Grande do Sul, foram analisados citogeneticamente. As duas espĂ©cies apresentaram um nĂșmero diplĂłide de 56 cromossomos, com P. nigribarbis mostrando um cariĂłtipo de 20m + 20sm + 4st + 12a, NF igual a 100; e P. maculatus com 24m + 20sm + 6st + 6a e NF igual 106. As NORs foram evidenciadas em apenas um par de cromossomos subtelocĂȘntricos, na regiĂŁo terminal do braço longo, nas duas espĂ©cies estudadas, sendo coincidentes com a banda C e CMA3; o DAPI nestas regiĂ”es se mostrou negativo. Parapimelodus nigribarbis apresentou um maior nĂșmero de bandas heterocromĂĄticas do que P. maculatus, distribuĂ­das principalmente em regiĂ”es terminais, sendo observada nesta Ășltima espĂ©cie uma banda intersticial no braço curto do primeiro par metacĂȘntrico. Banda C + CMA3 evidenciou em P. nigribarbis e P. maculatus a heterocromatina associada Ă  NOR rica em GC, sendo encontrada na primeira espĂ©cie outras regiĂ”es fluorescentes. Com banda C + DAPI vĂĄrias regiĂ”es cromossĂŽmicas foram observadas nas duas espĂ©cies, inclusive a porção intersticial encontrada em P. maculatus, revelando que a heterocromatina possui uma maior quantidade de regiĂ”es AT ricas em sua composição.A cytogenetic study was conducted on specimens of Parapimelodus nigribarbis and Pimelodus maculatus collected in the lago GuaĂ­ba drainage, Porto Alegre, Rio Grande do Sul, Brazil. The two species had a diploid number of 56 chromosomes, with P. nigribarbis showing a karyotype of 20m + 20sm + 4st + 12a with FN of 100, and P. maculatus showing a karyotype of 24m + 20sm + 6st + 6a with FN of 106. NORs were demonstrated in both species in only one pair of subtelocentric chromosomes, in the terminal region of the long arm, which was coincident with C- banding and CMA3 staining, while DAPI staining was negative in these regions. Parapimelodus nigribarbis had a greater number of heterochromatic bands than did P. maculatus, which were distributed mainly in the terminal regions, where the latter species showed an interstitial band on the short arm of the first metacentric pair. C-banding plus CMA3 demonstrated heterochromatin that was associated with GC-rich NORs in both P. nigribarbis and P. maculatus, although other fluorescent regions were also observed in the former species. With C-banding plus DAPI, various chromosomal regions were stained in the two species, along with interstitial staining in P. maculatus, indicating that heterochromatin contained a greater quantity of AT-rich regions

    Cytogenetics of species of the families Pimelodidae and Rhamdiidae (Siluriformes)

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    Only 33 species among about 300 belonging to the families Pimelodidae and Rhamdiidae have been studied cytogenetically. The diploid number varies from 2n = 46 to 2n = 63 chromosomes, with the karyotypes often being of the meta/submetacentric type. As a result, there is generally a very elevated fundamental number

    Cytogenetic characterization of a population of Bryconamericus aff. iheringii (Characidae,Tetragonopterinae)

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    A cytogenetic analysis of thirteen specimens of Bryconamericus aff. Iheringii revealed a diploid number of 52 chromosomes and a karyotype of 8M+22SM+10ST+12A with a fundamental number (FN) of 92. The nucleolus organizer regions (NORs) were studied by means of AgNO3 and CMA3 staining as well as by FISH using an 18S rDNA probe. NORs were found to be located at the terminal position on the short arm of the submetacentric chromosome pair. C-banding showed strong telomeric and centromeric staining in the majority of the chromosomes, and a similar pattern was observed after treatment with AluI restriction enzym

    Karyotypical characterization from stock of Nile tilapia, Oreochromis niloticus, at Londrina State University, PR, Brazil, through several techniques of chromosomes band

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    Foram analisados citogeneticamente 14 indivĂ­duos de tilĂĄpia do Nilo, Oreochromis niloticus que fazem parte do estoque de reposição de reprodutores da Estação de Piscicultura da Universidade Estadual de Londrina, ParanĂĄ, Brasil. Todos os indivĂ­duos apresentaram o mesmo nĂșmero diplĂłide de 44 cromossomos. As NORs foram observadas em quatro cromossomos com marcaçÔes em posição terminal do braço curto e a hibridação “in situ” (FISH) com sonda de 18S tambĂ©m evidenciou a presença de dois pares de cromossomos contendo cĂ­strons ribossĂŽmicos. O tratamento com os fluorocromos CMA3 e DAPI, respectivamente, nĂŁo mostrou bandas brilhantes em nenhum cromossomo do complemento. A Banda C (CBG) evidenciou, regiĂ”es de heterocromatina distribuĂ­das em vĂĄrios cromossomos nas regiĂ”es centromĂ©ricas, sendo observadas algumas marcaçÔes em regiĂ”es telomĂ©ricas, principalmente no maior par de cromossomos do complemento, um par apresentou-se quase totalmente heterocromĂĄtico. Os resultados obtidos estĂŁo de acordo com os dados disponĂ­veis na literatura, porĂ©m, quando analisadas as bandas C e as NORs, foram evidenciadas algumas diferenças que aparentemente caracterizam a população local de peixes da Universidade Estadual de Londrina.14 specimens of Nile’s tilapia were analyzed cytogenetically, Oreochromis niloticus, that belong to the stock of fish breeding from the Freshwater Aquaculture Station of the Londrina State University in the ParanĂĄ, Brazil. All specimens presented the same disploid number of 44 chromosomes. The NORs were observed in four chromosomes with marks in terminal position of the short arm and the hybridization “in situ” (FISH) with probe of 18 S also evidenced the presence of two pairs of chromosomes containing ribbosomic cistrons. The treatment with the fluochromes CMA3 and DAPI, respectively, didn’t show shinning bands in any chromosome of the complement. The band C (CBG) evidenced regions of heterochromatin distributed on several chromosomes in the centromeric regions, being observed some marks in telomeric regions, mainly on the biggest pair of chromosomes of the complement, a pair presented itself almost totally heterochromatic. The obtained results are in accordance with the data found in literature, nevertheless when the C bands and NORs were analyzed, were evidenced some differences that apparently characterized the local fish population of the Londrina State University. Key words: Cytogenetics, Oreochromis niloticus, NORs, CMA3, DAPI, fish, heterochromatin
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