Comparative chromosome mapping of U2 snRNA and 5S rRNA genes in Gymnotus species (Gymnotiformes, Gymnotidae): evolutionary dynamics and sex chromosome linkage in G . pantanal.
A comparative mapping of U2 small nuclear RNA (snRNA) and 5S ribosomal RNA (rRNA) genes was performed in 6 Gymnotus species. All species analyzed presented the U2 snDNA organized in conspicuous blocks and not co-located with rRNA genes. In addition, 5 species showed the U2 snDNA located in a single pair of chromosomes, which seems to be a conserved trait in this genus. Conversely, G. pantanal was the only species displaying several terminal signals in different chromosome pairs, including the X1 sex chromosome but not the Y chromosome. This is the first report of U2 snRNA genes in sex chromosomes of fishes. The absence of sites in the Y chromosome of G. pantanal indicates a possible loss of terminal segments of the chromosomes involved in the Y formation.
Departamento de Morfologia, Instituto de Biociências de Botucatu, Universidade Estadual Paulista, Botucatu, Brazil.
Ricardo
R
Utsunomia
Priscilla C
PC
Scacchetti
José C
JC
Pansonato-Alves
Claudio
C
Oliveira
Fausto
F
Foresti
D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D002874:Chromosome Mapping; D004275:DNA, Ribosomal / Q000235:genetics*; D008040:Genetic Linkage; D023702:Gymnotiformes / Q000145:classification / Q000235:genetics*; D059785:Karyotype; D012341:RNA, Ribosomal, 5S / Q000235:genetics*; D012342:RNA, Small Nuclear / Q000235:genetics*; D017422:Sequence Analysis, DNA; D012730:Sex Chromosomes / Q000235:genetics*
D004275:DNA, Ribosomal; D012341:RNA, Ribosomal, 5S; D012342:RNA, Small Nuclear; C405484:U2 small nuclear RNA