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Open Access Highly Accessed Research article

Integrating cytogenetics and genomics in comparative evolutionary studies of cichlid fish

Juliana Mazzuchelli1, Thomas David Kocher2, Fengtang Yang3 and Cesar Martins1*

Author affiliations

1 Department of Morphology, Bioscience Institute, UNESP - São Paulo State University, 18618-970, Botucatu, SP, Brazil

2 Department of Biology, University of Maryland, College Park, MD, 20742, USA

3 Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, UK

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Citation and License

BMC Genomics 2012, 13:463  doi:10.1186/1471-2164-13-463

Published: 9 September 2012

Abstract

Background

The availability of a large number of recently sequenced vertebrate genomes opens new avenues to integrate cytogenetics and genomics in comparative and evolutionary studies. Cytogenetic mapping can offer alternative means to identify conserved synteny shared by distinct genomes and also to define genome regions that are still not fine characterized even after wide-ranging nucleotide sequence efforts. An efficient way to perform comparative cytogenetic mapping is based on BAC clones mapping by fluorescence in situ hybridization. In this report, to address the knowledge gap on the genome evolution in cichlid fishes, BAC clones of an Oreochromis niloticus library covering the linkage groups (LG) 1, 3, 5, and 7 were mapped onto the chromosomes of 9 African cichlid species. The cytogenetic mapping data were also integrated with BAC-end sequences information of O. niloticus and comparatively analyzed against the genome of other fish species and vertebrates.

Results

The location of BACs from LG1, 3, 5, and 7 revealed a strong chromosomal conservation among the analyzed cichlid species genomes, which evidenced a synteny of the markers of each LG. Comparative in silico analysis also identified large genomic blocks that were conserved in distantly related fish groups and also in other vertebrates.

Conclusions

Although it has been suggested that fishes contain plastic genomes with high rates of chromosomal rearrangements and probably low rates of synteny conservation, our results evidence that large syntenic chromosome segments have been maintained conserved during evolution, at least for the considered markers. Additionally, our current cytogenetic mapping efforts integrated with genomic approaches conduct to a new perspective to address important questions involving chromosome evolution in fishes.

Keywords:
Cichlidae; Genome evolution; Molecular cytogenetics; Chromosome; Linkage groups; BACs