| Autor: |
Santos da Silva K; Cytogenetics Laboratory, Center for Advanced Biodiversity Studies Science Institute Biological, Federal University of Pará, Belém 66075-110, Brazil., Glugoski L; Fish Cytogenetics Laboratory, Federal University of São Carlos, São Carlos 13565-905, Brazil.; Laboratory of Chromosome Biology: Structure and Function Department of Structural Biology, Molecular and Genetic, University of Ponta Grossa State, Ponta Grossa 84010-330, Brazil., Vicari MR; Laboratory of Chromosome Biology: Structure and Function Department of Structural Biology, Molecular and Genetic, University of Ponta Grossa State, Ponta Grossa 84010-330, Brazil., de Souza ACP; Laboratory of Amazon Ichthyofauna Study, Federal Institute of Pará, Abaetetuba 68440-000, Brazil., Akama A; Department of Zoology, Paraense Emilio Goeldi Museum, Belém 66040-170, Brazil., Pieczarka JC; Cytogenetics Laboratory, Center for Advanced Biodiversity Studies Science Institute Biological, Federal University of Pará, Belém 66075-110, Brazil., Nagamachi CY; Cytogenetics Laboratory, Center for Advanced Biodiversity Studies Science Institute Biological, Federal University of Pará, Belém 66075-110, Brazil. |
| Abstrakt: |
Ancistrus is a highly diverse neotropical fish genus that exhibits extensive chromosomal variability, encompassing karyotypic morphology, diploid chromosome number (2n = 34-54), and the evolution of various types of sex chromosome systems. Robertsonian rearrangements related to unstable chromosomal sites are here described. Here, the karyotypes of two Ancistrus species were comparatively analyzed using classical cytogenetic techniques, in addition to isolation, cloning, sequencing, molecular characterization, and fluorescence in situ hybridization of repetitive sequences (i.e., 18S and 5S rDNA; U1, U2, and U5 snDNA; and telomere sequences). The species analyzed here have different karyotypes: Ancistrus sp. 1 (2n = 38, XX/XY) and Ancistrus cirrhosus (2n = 34, no heteromorphic sex chromosomes). Comparative mapping showed different organizations for the analyzed repetitive sequences: 18S and U1 sequences occurred in a single site in all populations of the analyzed species, while 5S and U2 sequences could occur in single or multiple sites. A sequencing analysis confirmed the identities of the U1, U2, and U5 snDNA sequences. Additionally, a syntenic condition for U2-U5 snDNA was found in Ancistrus . In a comparative analysis, the sequences of rDNA and U snDNA showed inter- and intraspecific chromosomal diversification. The occurrence of Robertsonian rearrangements and other dispersal mechanisms of repetitive sequences are discussed. |
