Genomic Organization of Repetitive DNAs and Differentiation of an XX/XY Sex Chromosome System in the Amazonian Puffer Fish, Colomesus asellus (Tetraodontiformes).
Cytogenet Genome Res
; 153(2): 96-104, 2017.
Article
em En
| MEDLINE
| ID: mdl-29186711
ABSTRACT
The genus Colomesus is the sole representative of the family Tetraodontidae in the Amazon region. Here, Colomesus asellus was analyzed using conventional and molecular cytogenetic protocols. Its diploid chromosome number is 2n = 46 with 12 meta-, 10 submeta-, 16 subtelo-, and 8 acrocentric chromosomes and a fundamental number of FN = 84. An XX/XY sex chromosome system was identified. Mapping of 18S rDNA correlated with the nucleolus organizer regions (Ag-NORs) in the short arms of the 2 X chromosomes in females and in the Y chromosome in males. C-banding revealed heterochromatin in the centromeric regions of all chromosomes, except for pair 3. Prominent sex chromosome-specific heterochromatin amplification was observed, covering the short arms of the Y chromosome almost entirely. FISH with telomeric and tropomyosin (tpm1) sequences, respectively, revealed terminal signals in all chromosomes. The analysis of extended DNA fibers confirmed the colocalization and the interspersed pattern of the telomeric and tpm1 sequences. Thus, this study highlights the remarkable evolutionary dynamism presented by the Amazonian puffer fish regarding the differentiation of a heteromorphic XY sex chromosome system and a particular sex-specific amplification of rDNA sites. This is the first record of such an association in the Tetraodontidae family.
Palavras-chave
Texto completo:
1
Bases de dados:
MEDLINE
Assunto principal:
Cromossomos Sexuais
/
Processos de Determinação Sexual
/
Tetraodontiformes
Limite:
Animals
País/Região como assunto:
America do sul
/
Brasil
Idioma:
En
Revista:
Cytogenet Genome Res
Assunto da revista:
GENETICA
Ano de publicação:
2017
Tipo de documento:
Article
País de afiliação:
Brasil