Navegando por Assunto "Peixe de água doce - Amazônia"

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Novas abordagens evolutivas em peixes da Amazônia: mapeamento de elementos repetitivos como marcadores para estudos em espécies do clado Peckoltia (Siluriformes, Loricariidae)
(Universidade Federal do Pará, 2018-04-30) PETY, Ananda Marques; NORONHA, Renata Coelho Rodrigues; http://lattes.cnpq.br/0860824558237244
Cytogenetic data provide important information on the diversity of Loricariidae, as they corroborate the classification analyzes of the species not described and help in the understanding of inter-intraspecific diversity. However, among the species of the Peckoltia clade, the determination of the number of chromosomes alone does not resolve these questions, since most species exhibit a stable diploid (2n) number. Thus, the use of other chromosomal markers is necessary to clarify the genomic organization of these species and to understand their diversity. The physical mapping of repetitive DNA has been widely used as an important tool in the study of taxonomic and evolutionary problems in fish, as well as to understand the processes of genomic organization and diversification. The objective of the present work was to map ribosomal sites (rDNA) 5S and 18S in Ancistomus feldbergae and five species of Peckoltia: P. cavatica; P. multispinis; P. oligospila; P. sabaji and P.vittata, and discuss the mechanisms of organization and diversification of these sequences. The results of the present study demonstrate that all six species analyzed have a karyotype composed of 52 chromosomes but have divergent karyotype formulas. Nucleolus Organizing Regions (NOR) of the single type were observed in Ancistomus feldbergae, P. cavatica, P. multispinis and P.vittata, while multiple NORs were found in P. oligospila and P. sabaji. Extensive variations in the number and location of 5S and 18S rDNA sites among species were observed. These data indicate that inversions are not the only most important events in karyotype evolution in this group and should be useful in identifying the species studied here. In addition to inversions, transpositions are important evolutionary events involved, at least in rDNA clusters that spread in Peckoltia and probably in other species of Hypostominae.