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Made available in DSpace on 2021-06-25T10:57:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Small nuclear RNA (snRNA) is a class of molecules involved in the processing of pre-mRNA and in regulatory cell processes. snRNAs are always associated with a set of specific proteins. The complexes are referred to as small nuclear ribonucleoproteins, and spliceosome U RNAs are their most common snRNA components. The repetitive sequences of U snDNAs have been cytogenetically mapped in several species of Arthropoda, fishes, and mammals; however, their distribution remains unknown in amphibians. Here, we show results of FISH mapping of U2 snDNA repetitive sequences in species of the amphibian genus Leptodactylus to reveal the distribution patterns of this sequence in their karyotypes. The probe hybridized in the metacentric chromosome pair 6 in Leptodactylus fuscus, L. gracilis, L. latrans, L. chaquensis, L. petersii, L. podicipinus, and L. brevipes. A different pattern was observed in L. labyrinthicus with hybridization signals in 4 chromosome pairs. The same localization of U2 gene sequences in most of the species analyzed suggests a relatively conserved pattern and a similarity of the chromosome 6 among these species of Leptodactylus. Departamento de Biologia Geral e Aplicada Instituto de Biociências Universidade Estadual Paulista UNESP Departamento de Biodiversidade e Centro de Aquicultura Instituto de Biociências Universidade Estadual Paulista UNESP Departamento de Biologia Geral e Aplicada Instituto de Biociências Universidade Estadual Paulista UNESP Departamento de Biodiversidade e Centro de Aquicultura Instituto de Biociências Universidade Estadual Paulista UNESP

Made available in DSpace on 2020-12-12T02:00:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-04-01 Most eukaryotic genomes contain substantial portions of repetitive DNA sequences. These are located primarily in highly compacted heterochromatin and, in many cases, are one of the most abundant components of the sex chromosomes. In this sense, the anuran Proceratophrys boiei represents an interesting model for analyses on repetitive sequences by means of cytogenetic techniques, since it has a karyotype with large blocks of heterochromatin and a ZZ/ZW sex chromosome system. The present study describes, for the first time, families of satellite DNA (satDNA) in the frog P. boiei. Its genome size was estimated at 1.6 Gb, of which 41% correspond to repetitive sequences, including satDNAs, rDNAs, transposable elements, and other elements characterized as non-repetitive. The satDNAs were mapped by FISH in the centromeric and pericentromeric regions of all chromosomes, suggesting a possible involvement of these sequences in centromere function. SatDNAs are also present in the W sex chromosome, occupying the entire heterochromatic area, indicating a probable contribution of this class of repetitive DNA to the differentiation of the sex chromosomes in this species. This study is a valuable contribution to the existing knowledge on repetitive sequences in amphibians. We show the presence of repetitive DNAs, especially satDNAs, in the genome of P. boiei that might be of relevance in genome organization and regulation, setting the stage for a deeper functional genome analysis of Proceratophrys. Departamento de Biologia Instituto de Biociências Universidade Estadual Paulista - UNESP, Av. 24A, 1515 Departamento de Zoologia e Centro de Aquicultura Instituto de Biociências Universidade Estadual Paulista - UNESP Departamento de Biologia Instituto de Biociências Universidade Estadual Paulista - UNESP, Av. 24A, 1515 Departamento de Zoologia e Centro de Aquicultura Instituto de Biociências Universidade Estadual Paulista - UNESP