Cytogenetic analysis and chromosomal characteristics of the polymorphic 18S rDNA in the fish Prochilodus lineatus (Characiformes, Prochilodontidae)

Genetics and Molecular Biology

Marcelo Ricardo Vicari²  Mara Cristina De Almeida¹  Luiz Antonio Carlos Bertollo²  Orlando Moreira-filho²  Roberto Ferreira Artoni¹ 

[1] ,Universidade Federal de São Carlos Departamento de Genética e Evolução Laboratório de CitogenéticaSão Carlos SP ,Brazil

关键词: fish cytogenetics;    Prochilodus;    karyotype;    minor and major rDNA;    NOR polymorphism;   

DOI  :  10.1590/S1415-47572006000400008

来源: SciELO

【 摘 要 】

We used differential staining techniques (BSG, GTG, AgNO3, DAPI and CMA3 banding) and fluorescent in situ hybridization (FISH) with 5S and 18S probes to investigated the karyotypic and cytogenetic chracteristics of Prochilodus lineatus specimens from a population in Vila Velha state park (Parque Estadual de Vila Velha, Ponta Grossa, Paraná state, southern Brazil). The specimens studied showed the same karyotype as that found in other P. lineatus populations, i.e. 2n = 54 biarmed chromosomes (40m + 14 sm) and c-positive heterochromatin preferentially located pericentromerically in all chromosomes. The presence of partial or totally heterochromatic supernumerary chromosomes with numeric intra-individual variation was confirmed in the analyzed population. The nucleolar organizing regions (NORs) were interstitially situated on the long arm of chromosome pair 4 directly beneath the centromere. The differential banding techniques and FISH revealed NOR size polymorphism due to structural events such as breaks and duplication of the larger rDNA site cluster. We also observed syntenic localization of the 5S ribosomal genes in the distal segment of the 45S cluster.

【 授权许可】

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