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|Title:||Repetitive DNA and meiotic behavior of sex chromosomes in Gymnotus pantanal (Gymnotiformes, Gymnotidae)|
|Authors:||Silva, M. R. da|
Matoso, D. A.
Vicari, Marcelo Ricardo
Almeida, Mara Cristina de
Margarido, Vladimir Pavan
Artoni, Roberto Ferreira
In Situ Hybridization, Fluorescence
Molecular Sequence Data
Repetitive Sequences, Nucleic Acid
Sequence Analysis, Dna
|metadata.dc.publisher.journal:||Cytogenetic and Genome Research|
|metadata.dc.relation.ispartof:||Volume 135, Número 2, Pags. 143-149|
|Abstract:||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.|
|Appears in Collections:||Artigos|
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