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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Initial steps in XY chromosome differentiation in Hoplias malabaricus and the origin of an X1X2Y sex chromosome system in this fish group

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Cioffi, M. B. [1] ; Bertollo, L. A. C. [1]
Total Authors: 2
[1] Univ Fed Sao Carlos, Dept Genet & Evolucao, BR-13565905 Sao Paulo - Brazil
Total Affiliations: 1
Document type: Journal article
Source: HEREDITY; v. 105, n. 6, p. 554-561, DEC 2010.
Web of Science Citations: 44

The neotropical fish, Hoplias malabaricus, is well known for its population-specific karyotypic diversity and the variation of its sex chromosomes. Seven karyomorphs (A to G) have been previously described with an XY, X(1)X(2)Y and XY(1)Y(2) sex chromosome system found in karyomorphs B, D and G, respectively. We compared the chromosomal characteristics of karyomorphs C and D using C-banding, staining with CMA(3) and DAPI, and by mapping the location of 18S rDNA, 5SHindIII-DNA and (TTAGGG)(n) repeat sequences. Our results show conserved karyotypes in both karyomorphs, a nascent XX/XY sex chromosome system in karyomorph C and the origin of neo-Y chromosome in karyomorph D. The X and Y chromosomes of karyomorph C differ only slightly because of the amplification of repetitive sequences on the X chromosome, resulting in a homomorphic condition in all females and a heteromorphic condition in all males examined. Our study showed that chromosomes X and 20 of karyomorph C have similar patterns to the X(1) and X(2) chromosomes of karyomorph D, and are probably homologous. We showed that the neo-Y chromosome of karyomorph D shares similar patterns to the chromosomes Y and 20 of karyomorph C, and probably evolved through tandem fusion between Ypter/20pter. An interstitial site of the satellite 5SHindIII-DNA on the neo-Y reinforces the hypothesized dicentric nature of this chromosome. Our study shows the initial steps in XY chromosome differentiation in H. malabaricus and, in a broader context, contributes to the understanding of the evolutionary pathway leading to a multiple X(1)X(2)Y sex chromosome system in fishes. Heredity (2010) 105, 554-561; doi:10.1038/hdy.2010.18; published online 10 March 2010 (AU)

FAPESP's process: 07/05565-5 - Chromosome markers in Hoplias malabaricus (Characiformes, Erythrinidae): comparative cytogenetics among cytotypes
Grantee:Marcelo de Bello Cioffi
Support Opportunities: Scholarships in Brazil - Master