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Open Access Research article

A gene-based radiation hybrid map of the gilthead sea bream Sparus aurata refines and exploits conserved synteny with Tetraodon nigroviridis

Elena Sarropoulou12*, Rafaella Franch3, Bruno Louro4, Deborah M Power4, Luca Bargelloni3, Antonios Magoulas1, Fabrice Senger57, Matina Tsalavouta18, Tomaso Patarnello35, Francis Galibert6, Georgios Kotoulas1 and Robert Geisler2

Author Affiliations

1 Institute of Marine Biology and Genetics, Hellenic Center for Marine Research, Crete, Greece

2 MPI fuer Entwicklungsbiologie, Spemannstr.35/III D-72076 Tuebingen F.R. Germany

3 Dipartimento di Sanità Pubblica, Patologia Comparata e Igiene Veterinaria, Università di Padova, Padova Italy

4 Campus de Gambelas, 8000-810 Faro, Portugal

5 Department of Biology, University of Padova, Padova, Italy

6 CNRS UMR 6061 Génétique et Développement, Université de Rennes 1, Faculté de médecine, 2 avenue du Pr Léon Bernard, 35043 Rennes Cedex, France

7 CNRS UMR6026, Interactions Cellulaires et Moléculaires, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France

8 Current address: School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland

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BMC Genomics 2007, 8:44  doi:10.1186/1471-2164-8-44

Published: 7 February 2007

Abstract

Background

Comparative teleost studies are of great interest since they are important in aquaculture and in evolutionary issues. Comparing genomes of fully sequenced model fish species with those of farmed fish species through comparative mapping offers shortcuts for quantitative trait loci (QTL) detections and for studying genome evolution through the identification of regions of conserved synteny in teleosts. Here a comparative mapping study is presented by radiation hybrid (RH) mapping genes of the gilthead sea bream Sparus aurata, a non-model teleost fish of commercial and evolutionary interest, as it represents the worldwide distributed species-rich family of Sparidae.

Results

An additional 74 microsatellite markers and 428 gene-based markers appropriate for comparative mapping studies were mapped on the existing RH map of Sparus aurata. The anchoring of the RH map to the genetic linkage map resulted in 24 groups matching the karyotype of Sparus aurata. Homologous sequences to Tetraodon were identified for 301 of the gene-based markers positioned on the RH map of Sparus aurata. Comparison between Sparus aurata RH groups and Tetraodon chromosomes (karyotype of Tetraodon consists of 21 chromosomes) in this study reveals an unambiguous one-to-one relationship suggesting that three Tetraodon chromosomes correspond to six Sparus aurata radiation hybrid groups. The exploitation of this conserved synteny relationship is furthermore demonstrated by in silico mapping of gilthead sea bream expressed sequence tags (EST) that give a significant similarity hit to Tetraodon.

Conclusion

The addition of primarily gene-based markers increased substantially the density of the existing RH map and facilitated comparative analysis. The anchoring of this gene-based radiation hybrid map to the genome maps of model species broadened the pool of candidate genes that mainly control growth, disease resistance, sex determination and reversal, reproduction as well as environmental tolerance in this species, all traits of great importance for QTL mapping and marker assisted selection. Furthermore this comparative mapping approach will facilitate to give insights into chromosome evolution and into the genetic make up of the gilthead sea bream.