Journal
GENETICA
Volume 144, Issue 5, Pages 591-599Publisher
SPRINGER
DOI: 10.1007/s10709-016-9927-9
Keywords
Constitutive heterochromatin; 5S rDNA; Banjo catfish; Multiple sex chromosomes
Categories
Funding
- Instituto Nacional de Pesquisas da Amazonia/Genetica, Conservacao e Biologia Evolutiva (INPA/GCBEv)
- Fundacao de Amparo a Pesquisas do Estado do Amazonas [UNIVERSAL AMAZONAS/FAPEAM 030/2013, PRONEX FAPEAM/CNPq 003/2009]
- Center for Studies of Adaptation to Environmental Changes in the Amazon (INCT ADAPTA) [FAPEAM/CNPq 573976/2008-2]
- Edital MCT/CNPq/MEC/CAPES/FNDCT-Acao Transversal/FAPs [47/2010]
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We analyzed one Bunocephalus coracoideus population from the Negro River basin using cytogenetic techniques. The results showed a diploid number of 42 chromosomes in both sexes, with the karyotypic formula 4m + 14sm + 24a and fundamental number (FN) = 60 for females and the formula 5m + 14sm + 23a and FN = 61 for males, constituting an X1X1X2X2/X1Y1X2Y2 multiple sex chromosome system. The constitutive heterochromatin is distributed in the pericentromeric regions of most of the chromosomes, except for the sex chromosomes, of which the X-1, X-2, and Y-1 chromosomes were euchromatic and the Y-2 chromosome was partially heterochromatic. 18S rDNA mapping confirmed the presence of nucleolar organizer regions on the short arms of the fifth chromosomal pair for both sexes. The 5S rDNA is present in the terminal regions of the short arms on the 2nd, 10th, and 12th pairs and on the X-2 chromosome of both sexes; however, we observed variations in the presence of these ribosomal cistrons on the Y-1 chromosome, on which the cistrons are pericentromeric, and on the Y-2 chromosome, on which these cistrons are present in the terminal portions of the short and long arms. Telomeric sequences are located in the terminal regions of all of the chromosomes, particularly conspicuous blocks on the 10th and 12th pairs and internal telomeric sequences in the centromeric regions of the 1st, 6th, and 9th pairs for both sexes. This work describes an new sex chromosomes system for the Siluriformes and increases our genetic knowledge of the Aspredinidae family.
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