Repetitive DNA and meiotic behavior of sex chromosomes in Gymnotus pantanal (Gymnotiformes, Gymnotidae)
Neotropical fishes have a low rate of chromosome differentiation between sexes. The present study characterizes the first meiotic analysis of sex chromosomes in the order Gymnotiformes. Gymnotus pantanal - females had 40 chromosomes (14m/sm, 26st/a) and males had 39 chromosomes (15m/sm, 24st/a), wit...
| Autor principal: | Silva, M. R. da |
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| Outros Autores: | Matoso, D. A., Vicari, Marcelo Ricardo, Almeida, Mara Cristina de, Margarido, Vladimir Pavan, Artoni, Roberto Ferreira |
| Grau: | Artigo |
| Idioma: | English |
| Publicado em: |
Cytogenetic and Genome Research
2020
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| Acesso em linha: |
https://repositorio.inpa.gov.br/handle/1/18136 |
| Resumo: |
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Neotropical fishes have a low rate of chromosome differentiation between sexes. The present study characterizes the first meiotic analysis of sex chromosomes in the order Gymnotiformes. Gymnotus pantanal - females had 40 chromosomes (14m/sm, 26st/a) and males had 39 chromosomes (15m/sm, 24st/a), with a fundamental number of 54 - showed a multiple sexual determination chromosome system of the type X 1X 1X 2X 2/X 1X 2Y. The heterochromatin is restricted to centromeres of all chromosomes of the karyotype. The meiotic behavior of sex chromosomes involved in this system in males is from a trivalent totally pared in the pachytene stage, with a high degree of similarity. The cells of metaphase II exhibit 19 and 20 chromosomes, normal disjunction of sex chromosomes and the formation of balanced gametes with 18 + Y and 18 + X 1X 2 chromosomes, respectively. The small amount of heterochromatin and repetitive DNA involved in this system and the high degree of chromosome similarity indicated a recent origin of the X 1X 1X 2X 2/X 1X 2Y system in G. pantanal and suggests the existence of a simple ancestral system with morphologically undifferentiated chromosomes. Copyright © 2011 S. Karger AG. |